NATIONAL BUREAU OF STANDARDS REPORT

8174

PROCEDURES FOR PRECISE DETERMINATION

OF THERMAL RADIATION PROPERTIES

ANNUAL SUMMARY REPORT

October 1, 1962 - October 31, 1963

Contract No. DO 33(616) 61-02

Task No. 73603

UNITED STATES AIR FORCE

AERONAUTICAL SYSTEMS DIVISION

AIR FORCE SYSTEMS COMMAND

WRIGHT-PATTERSON AIR FORCE BASE, OHIO

U.S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

to
U. S. DEPARTMENT OF COMMERCE

Luther H. Hodges, Secretary

NATIONAL BUREAU OF STANDARDS

A. V. Astin, Director

THE NATIONAL BUREAU OF STANDARDS

Functions and Activities

The functions of the National Bureau of Standards include the development and maintenance of the national standards of measurement and the provision of means and methods for making measure - ments consistent with these standards; the determination of physical constants and properties of materials; the development of methods and instruments for testing materials, devices, and structures; advisory services to government agencies on scientific and technical problems; invention

and development of devices to serve special needs of the Government; and the development of standard practices, codes, and specifications, including assistance to industry, business and con- sumers in the development and acceptance of commercial standards and simplified trade practice

recommendations. The work includes basic and applied research, development, engineering, instru- mentation, testing, evaluation, calibration services, and various consultation and information services. Research projects are also performed for other government agencies when the work relates

to and supplements the basic program of the Bureau or when the Bureau’s unique competence is required. The scope of activities is suggested by the listing of divisions and sections on the inside

of the back cover.

Publications

The results of the Bureau’s research are published either in the Bureau’s own series of publications or in the journals of professional and scientific societies. The Bureau itself publishes

three periodicals available from the Government Printing Office: The Journal of Research, published in four separate sections, presents complete scientific and technical papers; the Technical

News Bulletin presents summary and preliminary reports on work in progress; and Central Radio

Propagation Laboratory Ionospheric Predictions provides datafor determining the best frequencies

to use for radio communications throughout the world. There are also seven series of nonperiodical publications: Monographs, Applied Mathematics Series, Handbooks, Miscellaneous Publications, Technical Notes, Commercial Standards, and Simplified Practice Recommendations.

A complete listing of the Bureau’s publications can be found in National Bureau of Standards

Circular 460, Publications of the National Bureau of Standards, 1901 to June 1947 ($1.25), and the Supplement to National Bureau of Standards Circular 460, July 1947 to June 1957 ($1.50), and Miscellaneous Publication 240, July 1957 to June 1960 (includes Titles of Papers Published in Outside Journals 1950 to 1959) ($2.25); available from the Superintendent of Documents, Government

Printing Office, Washington, D.C., 20402.
NATIONAL BUREAU OF STANDARDS REPORT

NBS PROJECT NBS REPORT

1009-11-10491 8174

PROCEDURES FOR PRECISE DETERMINATION

OF THERMAL RADIATION PROPERTIES

ANNUAL SUMMARY REPORT

October 1 , 1962 - October 31, 1963

Joseph C. Richmond

David P. DeWitt

Warren D. Hayes Jr.

Contract No. DO 33(616) 61-02

Task No. 73603

to

UNITED STATES AIR FORCE

AERONAUTICAL SYSTEMS DIVISION

AIR FORCE SYSTEMS COMMAND

Wright-Patterson Air Force Base, Ohio

IMPORTANT NOTICE NATIONAL BUREAU OF STAN

for use within the Government. Bel and review. For this reason, the pi whole or in part, is not authorizec Bureau of Standards, Washington, [ the Report has been specifically pre

iccounting documents intended Approved for public release by the iected t0 additlonal evaluation

T-i- + p.u m *• it . * p

tin 8 of this Report, either in Director of the National Institute of ffice of the Direct0fi Natl0nal Standards and Technology (NIST) on October 9, 2015.

e Government agency for which

s tor its own use.

U.S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

I. OBJECTIVES

The broad objective of this program is to develop standard procedures,

and to select or design suitable equipment for the measurement of normal

spectral emittance and/or spectral reflectance of materials, particularly

those used in aircraft, missiles and space vehicles, at temperatures from

below room temperature to near the melting point of refractory materials

of interest, and over the wavelength range from the ultraviolet into the

far infrared. The specific objectives for the report period included

(1) development of instrumentation and techniques for measurement of normal spectral emittance in the temperature range of 2000° to 40Q0°F (1366°

to 2733 K), and over the wavelength range of 0.3 to 15 microns (2) extension of existing equipment and procedures for measurement of normal spectral emittance in the temperature range of 1000° to 2000°F (811° to 1366°K)

and wavelength range of 1 to 15 microns to the wavelength range of 15 to

35 microns and (3) preparation and calibration of working standards of

normal spectral emittance in the temperature range of 1000 to 2000 F and

the wavelength range of 15 to 35 microns. A further objective, covered

by Amendment No. 6 to the delivery order, called for the preparation and

calibration of disc standards of normal total emittance of polished platinum- 137o rhodium alloy and oxidized, sandblasted inconel over the temperature range of 1000° to 2000°F.

The work on development of equipment and procedures for measuring normal gpectral emittance at temperatures in the 2000 to 4000 F (1366° to

2733 K) range has proceeded on another project sponsored by the George C.

Marshall Space Flight Center of N.A.S.A. Reports covering work sponsored

by N.A.S.A. and by A.S.D. have been sent to both sponsors.

II. NORMAL SPECTRAL EMITTANCE EQUIPMENT

During the report period the major effort with the normal spectral

emittance equipment has been to extend the wavelength range of satisfactory operation. from 1 to 15 microns to 1 to 38 microns or beyond. A

cesium bromide prism and a thermocouple detector with a cesium bromide window, were available for use in the wavelength range of 15 to 40 microns.

The principal problem involved in work in this long-wavelength range

is in maintaining a satisfactory signal-to-noise ratio. At a temperature

of 800 K the radiant energy, per unit wavelength interval and unit area,

emitted by a blackbody radiator at 15 microns is about 33.6 times that

emitted at 40 microns. At 1400 K, this ratio increases to about 43.5.

Obviously, in order to maintain a satisfactory signal-to-noise ratio, the

noise will have to be reduced proportionately. To further complicate the

problem, absorption by atmospheric carbon dioxide and water vapor greatly

reduce the intensity of the flux reaching the detector, particularly at

wavelengths beyond about 34 microns.

1
In order to maintain a satisfactory signal- to-noise ratio, it was necessary to (a) keep the energy level as high as possible by reducing

atmospheric absorption, and (b) reduce all possible sources of noise to

the lowest possible levels. These sources include (1) Johnson noise in

the thermocouple detector, (2) noise from variable resistance of the rec- tifier contacts on the chopper shaft, (3) noise from the preamplifier and

amplifier, (4) background radiation from the chopper blade and interior

of the monochromator, and (5) scattered radiation within the monochromator. Although the latter two tend to be of constant intensity, they re- present a spurious signal and, hence, may be considered as noise.

The Johnson noise, item (1) above, could be reduced by cooling the

detector, which was not considered desirable. Significant reduction of

noise from items (2) and (3) would involve major modifications in the

electronic circuits of the equipment, which is considered beyond the

scope of the investigation at this time. Noise from source (4) could be

reduced by cooling the entire monochromator, which would make the cesium

bromide optical elements particularly vulnerable to attack by atmospheric

moisture. Source (5), scattered radiation within the monochromator, appeared to be one area where a sizeable reduction in noise could be

achieved without major changes in the equipment.

The two approaches selected to improve the usable signal -to-noise

ratio, especially in the long-wavelength region, were (1) to reduce scattered radiation within the monochromator as much as possible and (2) to

operate in a moisture-free C0 2-free atmosphere.

A. Reduction of Scattered Radiation

A special filter kit accessory was purchased for use with the Model

13 spectrophotometer. This consisted of (1) a silver chloride disc (2) a black polyethylene filter, and (3) a calcium fluoride reststrahlen plate.

The silver chloride disc transmits at wavelengths from 4.5 to 28 microns,

but is opaque to radiation of shorter wavelengths. The black polyethylene

filter transmits at wavelengths from 28 to 40 microns, but is opaque at

shorter wavelengths. The calcium fluoride reststrahlen plate is a good

mirror at wavelengths longer than 15 microns, but scatters radiation of

shorter wavelengths.

A special filter holder was built to accommodate the silver chloride

disc and black polyethylene filter. The filter holder was arranged so that either filter could be inserted or removed from a position immediately

in front of the entrance slit to the monochromator, without opening the optical path to the atmosphere.

The reststrahlen plate was mounted on the movable mirror mount in the

monochromator, where it could be inserted or removed by a remote control

lever mounted on the exterior of the monochromator case.

2
At the time these changes were made, it was decided that two mirrors in

the specimen beam, mounted between the chopper and combining optics, could

be removed and thus reduce absorption losses in the specimen beam. In order

to accomplish this, it was necessary to redesign the opaque air-tight cover

for this portion of the optical path.

Several baffles had previously been installed in the monochromator to

reduce as much as possible the stray radiation reaching the detector . The

design of these baffles was again examined, and several adjustments and modifications were made to improve their effectiveness.

B. Reduction in Atmospheric Absorption

A controlled atmosphere system, using super-dry nitrogen, had previously been built for use with the normal spectral emittance equipment. This

was found necessary for the attainment of the desired accuracy, particularly

in the spectral regions where the water vapor and carbon dioxide absorption

peaks occur.

The enclosure was designed to permit controlled leakage, so that during

a measurement it could be continuously swept out with COg-free super-dry nitrogen, which was supplied from a cylinder under a slight positive pressure.

With this system it was possible to maintain the relative humidity, as measured with a recording humidigraph, below 5% for periods of several hours at

a flow rate of about 2.5 cubic feet per minute. These conditions were satisfactory while working in the 1 to 15 micron wavelength range. However, se- rious absorption occurred under these conditions in the 35-40 micron range.

The plastic enclosure to the external optics was redesigned to reduce

the enclosed volume and all joints in the system were sealed to minimize

leakage. A new atmospheric purification system was designed and installed.

The new train is shown schematically in figure 1.

Air from the enclosure reaches the oilless compressor by a pipe not

shown on the diagram. There is a valve in this pipe that is adjusted to

provide the desired resistance to flow, so that a slight positive pressure

is maintained in the instrument enclosure, and a slight vacuum is maintained

at the compressor inlet. A needle valve, connected to a tee in the vacuum portion of this line is adjusted to provide a controlled leak of room air

into the compressor inlet, to compensate for the loss by leakage from the

high-pressure portion of the system. The loss by leakage is approximately

15 CFH, out of approximately 185 CFH that is being circulated.

Air from the compressor goes to a tank that serves as a ballast for the

system. Air from the tank, at a pressure of about 75 psi, is fed through

the coarse air filter, (2), and air filter, (6), where coarse dust and con- densed liquid are removed. The pressure is then reduced to about 60 psi by

the pressure regulator, (7), and fed through the silica gel drying tower,

(10), Askarite carbon dioxide absorbent, (11), the molecular sieve water

filter, (12), oil filter, (14), and dust filters, (15) and (16). The pressure drops from about 60 psi to about 10 psi in passing through these units.

3
8 4

Fig. 1. Schematic diagram of atmosphere purification system.

1. Air inlet from compressor and storage tank.

2. Coarse air filter. 3. Purge valve. 4. Combination temperature and pressure gage. 5. Valve.

6. Air filter. 7. Pressure regulator. 8. Gage,

combination pressure and temperature. 9. Safety

relief valve. 10. Water filter - silica gel.

11. Carbon dioxide filter, Askerite. 12. Water

filter, molecular sieve. 13. Moisture indicator.

14. Oil filter. 15. Dust filter, 11-15 micron.

16. Dust filter, 205 micron. 17. Gage, pressure,

0-30 psi. 18. Pressure regulator. 19. Gage,

pressure, 0-15 psi. 20. Surge tank. 21. Flow

meter. 22. Discharge to spectrometer enclosure.

4
A second pressure regulator, (18), is used to decrease the pressure to a few ounces per square inch, after which the air passes through a surge tank,

(20), and flow meter, (21), and into the instrument enclosure.

The manufacturer of the drying towers used in this system indicated

that the dew point of the air entering the instrument enclosure should be

below - 100°C. The humidity within the enclosure was below that measured by

the recording humidigraph.

Tests with the equipment have indicated that the water vapor absorption

peaks do not disappear until the equipment has been purged for several hours, even though the humidity of the atmosphere in the enclosure, as measured with

the humidigraph, drops quite rapidly. It is believed that films of water

vapor, adsorbed on optical elements and other surfaces within the enclosed

volume, contribute to the time required for complete purging of the system.

Because of the relatively long period required for purging, it is considered

desirable to maintain the dry atmosphere continuously, except when the en- closure must be opened to permit adjustment of the equipment or insertion of

a new specimen.

The drying capacity of the system becomes exhausted in less than 24

hours of operation. Most of the moisture and carbon dioxide enters the systems with the air admitted through the controlled leak. An automaticallycycled laboratory air dryer has been ordered to supply predried air to this

leak, which should remove at least 95% of the load from the silica gel drying tower (10 in figure 1) in the main purification train, and correspondingly lengthen the periods between recharges.

III. DATA PROCESSING ATTACHMENT

The manufacturer of the data-processing attachment to the normal spectral emittance equipment sent an engineer to the Bureau to correct the malfunctions that had been noted. These malfunctions consisted primarily of

unstable circuits which resulted in drift from the calibration settings of ' potentiometers controlling corrections for zero-line and 100%-line errors. The trouble was found to be in the digital portions of the circuits, and was corrected. A mechanical difficulty, binding of the gears in the correcting

potentiometer drive mechanism, was also found and corrected.

A. Computer Code for Making Corrections

Following these adjustments, the data-processing attachment operated

satisfactorily for a time, after which intermittant trouble developed in the

automatic correction circuits. However, it was established that the attachment correctly recorded, on punched paper tape, the "zero line”, n 100%> line",

and "specimen line." A program for the Bureau's SEAC computer computer was therefore designed by means of which the corrected spectral emittances could

be computed from the values that had been recorded on punched paper tape.

Use of the data-processing attachment and the computer in this way greatly

reduced the time required in obtaining useful data with the normal spectral

emittance equipment.

5
B. Errors in Correction Circuits

The errors in the correction circuits were difficult to locate and cor- rect. During a calibration run, the pulses produced by the analog- to-digital converter on the recorder pen shaft are recorded on magnetic tape. During a consequent specimen run the magnetic tape is played back synchronously

and the pulses are read from the tape, amplified, and used to drive a "100% line" and a "zero line" potentiometer up and down scale by means of a multistable vibrator circuit which actuates a reversible ratchet motor.

The pulses appeared to be recorded on the magnetic tape satisfactorily, but

did not drive the potentiometers up and down scale as required to make the

corrections

.

The manufacturer sent the engineer who had designed the data-processing

attachment to the Bureau, in an effort to find and correct the remaining difficulties .

Plug-in amplifiers of a new design were installed. These amplify the

pulses from the tape, and the outputs drive the ratchet motors. The equipment then appeared to operate satisfactorily for short periods of time, but over the 30-minute period required for a complete scan of the spectrum, errors accumulated that exceeded the design specifications. These errors could be due to missed pulses, or spurious pulses (the overall effect of a missed positive pulse or a spurious negative pulse would be the same).

A check of the ratchet motor circuits revealed some weak components,

which were replaced, but errors still persisted.

A check of the tape amplifiers indicated that at times the signal

strength was weak. The amplifiers were redesigned for more gain, and adjusted for optimum response to the recording tape being used. The basic

problem of accumulation of errors over periods of 15 minutes or more was

not eliminated.

It was noted that spurious signals were produced when the tape heads were touched. This was attributed to insufficient grounding of the tape

heads. The mounting plate containing the tape heads was insulated from

ground, and the heads themselves were connected to the ground lead of the

amplifiers, in order to provide an adequate ground without the possibility

of ground loop pick-up. This change improved operation of the equipment,

but did not eliminate completely the spurious counts.

A finite time is required to actuate the stepping motors. If two

pulses occur within a time interval shorter than the "dead time", the se- cond pulse is lost. On long runs many of the pulses occur due to random

backward or forward steps of only one pulse, which can occur rather rapidly

if the recorder pen chatters. In order to reduce this rapid random correction, a buffer register was introduced between the amplifier and stepping

motor, which resulted in the stepper motor not having to step for the first

forward or reverse signal following a change in direction (the motor did

step for the second and all subsequent pulses in one direction, however).

This buffer register reduced the operation of the stepper motor by 60 to

807,, but the accumulated errors still persisted.

6
The pen position counter was temporarily connected to the output of the

read amplifier, to follow the pulses at electronic speed. This was done to

determine whether the errors were due to the steppers being unable to follow

the pulses from the tape, or were due to failure to properly record the

pulses on the tape originally. The count indicated that the steppers were

accurately following the pulses on the tape, indicating that the trouble

probably originated in the recording circuits.

Observation of the output of the two recording multivibrators showed

apparent spurious pulses. The multivibrators were adjusted by increasing

the safety margin against spurious triggering, and by reducing the output

impedance. Operation was improved, but the accumulated errors still exceeded specification limits.

The buffer register was moved from between the read amplifier and stepping motor to between the pen analog-to-digital converter and the write multivibrator. The effect of this change was to prevent the extra pulses from

being recorded, rather than to record them and then eliminate them before

they reached the stepper motor. After this change was made, the equipment

operated satisfactorily.

C. Computation of 100 Selected Ordinates

The rigorous method of computing normal spectral emittance from spectral data may be expressed mathematically as follows:

00 E

ts - (1)

To

d"

where E = total normal emittance of specimen

ts

e = rate of energy emission (radiant flux) per unit area,

unit solid kngle and unit wavelength interval, within the wavelength interval A. to (X + dX), at temperature T.

E = normal spectral emittance of specimen at wavelength X and

temperature s T.

However, all computations from data are based upon finite wavelength

intervals, AX. The following equation applies to such computations:

ts

X

2 Z

\lAcZ

e bXE

sX

AX

( 2 )

Xi and Xg being selected to include substantially all of the flux emitted

by a blackbody radiator at the test temperature T.

7
In the weighted ordinate method uniform values of AX are used, and each

value of E s ^ must be weighted by a factor proportioned to . This value

of e b\ represents the flux emitted per unit area, unit solid angle and within

the wavelength interval X and (X + AX), by a blackbody at the test temperature,

T.

In the 100-selected ordinate method, the area under the spectral distribution curve for the radiant flux per unit area and unit solid angle emitted

by a blackbody radiator at the test temperature T is divided vertically into

100 slices of equal area. The 100 selected ordinates are then the 100 median

wavelengths of the 100 areas. In this case AX varies, but the quantity

e^AX is held constant at 0.01. Under these conditions, equation (2) can be

rewritten

:

Xioo

E ~ 0.01 EE. (3) ts Xi sX

In practice any desired degree of precision in the computation of E can

be attained by either the weighted ordinate method or the selected ordinlfe

method, by taking a large enough number of ordinates. With any given number

of ordinates, the computation error will be smaller by the selected ordinate

method than by the weighted ordinate method. With solids, whose spectral

emittance curves do not normally have sharp peaks or valleys, the 100- selectedordinate method gives values that have no significant computation error from

this source. m

The wavelengths representing the 100 selected ordinates were computed for

temperatures of 600°, 700°, 800°, 900°, 1000°, 1100°, 1200°, 1300° and 1400°K,

and are given in Table 1.

The 100 selected ordinates for temperatures of 800°, 1100°, 1300° and

1400°K were converted to digital form and punched on paper tape for use with

the data-processing attachment for computation of total normal emittance

during measurement of normal spectral emittance.

IV. CALIBRATION OF WORKING STANDARDS

The platinum, oxidized Kant ha 1 and oxidized Inconel working standards of

normal spectral emittance that had been transmitted to the Physics Laboratory,

A. S. D., in 1962 were returned to the National Bureau of Standards early in

1963 with a request that the Bureau arrange to distribute them as requested.

The standards are now offered for sale at a price of $175.00 each, plus

a surcharge of $4.00 per gram for the platinum standards. It is anticipated

that the supply of working standards will be augmented from time to time, as required, by preparation and calibration of additional standards. The sale

price of the standards is intended to cover the replacement cost.

8
Two types of 0.484 inch diameter disc working standards were prepared

for use at A.S.D. These were of polished platinum- 137, rhodium alloy and

oxidized Inconel, respectively.

A. Platinum- 137c Rhodium Working Standards

The platinum- 137o rhodium specimens were received from the fabricator in

the form of 0.035-inch sheet, cut into two strip specimens 1/4 x 8 in. in

size and five discs 0.484 inch in diameter. The original sheet of alloy from

which the specimens were cut was approximately 1 1/16 x 8 in. in size. The

1/4 x 8 inch strips were cut from the two edges of the original sheet, and the

discs were cut from the central portion of the remaining strip.

Each specimen was washed in hot tap water to which a commercial detergent

had been added, rinsed in running hot tap water, then in distilled water, and

finally in ethyl alcohol. Rubber surgical gloves were worn at all times while

handling the specimens, and they were touched only at the ends or edges after

cleaning. The specimens were dried in air and placed in a closed container,

supported by the ends or edges only, for storage prior to annealing.

All specimens were anpealed in an electric furnace with silicon carbide

heating elements. The strip specimens were hung by means of platinum hooks,

suspended from aluminum oxide rods in the furnace; the disc specimens were

supported by the edges only on ceramic forms resting on a rigid ceramic slab.

All of the specimens were then enclosed in a ceramic muffle. Starting with

ambient conditions, the temperature of the furnace was raised to 1523°K (1250°C) over a period of six hours, and held at that temperature for one hour. The

power was then turned off, and the specimens were allowed to cool in the furnace,

which required two days.

The specimens were removed from the furnace by means of cleaned, platinum

tipped tongs and were placed in individual cardboard boxes, to protect them

from contamination.

The two 1/4 x 8-inch strips were prepared for measurement by welding a platinum-platinum 107, rhodium thermocouple to each specimen. A shallow groove

was scratched in each specimen, normal to its axis and located at the midlength. The 10-mil thermocouple wires were separately welded to the specimen

by means of a condenser-discharge type of electronic spot welder. Each wire

was laid in the shallow groove to position it for welding, and the welding

operation was observed through a low-power microscope.

Three sets of curves were made for each strip specimen at each of three

temperatures, 800°, 1100° and 1300°K. Each set of curves consisted of (1) a 1007 curve, obtained when the two blackbody furnaces at the test temperature

served as sources for the respective beams, (2) a zero curve, obtained with

the specimen beam blocked near the specimen furnace, and (3) a specimen curve,

obtained with the comparison blackbody at the test temperature as source for

the comparison beam, and the hot specimen at the same temperature serving as source for the specimen beam. The height of each curve was recorded on punched paper tape at each 0.1 revolution of the wavelength dial over the

range corresponding to approximately 1 to 15 microns.

9
The punched paper tape containing the raw emittance data was fed into

the NBS SEAC computer, which then corrected the recorded emittance of the

specimen at each wavelength on the basis of the recorded 100% and zero curves.

The corrected emittance values for the six measurements, three each on two specimens, were then fed back into the computer, and the following values were computed at each of the approximately 110 wavelengths. ( 1 ), £, the

average emittance, (2) am, the standard deviation— due to error of measurement, computed as the average standard deviation of the three measurements

on each specimen about the mean for that specimen, and (3) as , the standard

deviation due to differences in specimens.

The values obtained on the platinum- 13% rhodium specimens are tabulated

in Table II, and are shown in figures 2 through 7.

The spectral emittance curves for the platinum-13% rhodium alloy, shown

in figure 2 at 800°K, figure 3 at 1100°K and figure 4 at 1300°K, are quite

similar to the corresponding curves for platinum.

The principal differences are that (1) in general, the emittance of the

platinum-13% rhodium alloy is higher than that of platinum at the same temperature and at the same wavelength, (2) the maximum at about 1.4 micron at

8Q0°K is lower for the platinum-13% rhodium alloy than for platinum, (3) the

maximum at about 1.36 micron for platinum and 1100°K has moved to about 1.12

microns for platinum-13% rhodium and (4) no evidence of a maximum at 15 mi- crons or beyond is seen in the platinum-13% rhodium data.

The standard deviations as and aro are plotted as a function of wavelength

in figure 5 at 800°K, figure 6 at 1100°K and figure 7 at 1300°K. In general

the am values show less variation with wavelength than the crs values. The

average values of amwere 0.23 at 800°K, 0.19 at 1100°K and 0.33 at 13QQ°K,

and the corresponding values of as were 0.25 at 800°K, 0.57 at 1100°K and

0.91 at 1300 K. However, the as values are based on only two specimens, and

hence are not highly reliable.

1/ All standard deviations in this study are precisely defined as "estimates

of the standard deviation of the parent population from which the measuretnents

were drawn." Mathematically

where x is an individual measurement, x is the average of n measurements on specimen one, and p is the number of specimens. (for data in this report,

n = 3 in all cases, and p = 2 for platinum-13% alloy and 6 for oxidized sandblasted Inconel.)

where x Is the overall average of the n x p measurements, n each on p specimens.

am

a

s

10
Fig. 2. Normal spectral emittance of 0.484-inch disc

q working standards of platinum-13% rhodium alloy at 800 K.

The plotted values are averages of six measured values,

WAVELENGTH, MICRONS

Fig. 3. Normal spectral emittance of 0.484-inch

disc working gtandards of platinum- 13% rhodium

alloy at 1100 K. The plotted values are averages

of six measured values, three each on two speci- mens .

11
r—i—

r

T

Fig. 4. Normal spectral emittance of 0.484-inch disc

working standards of platinm-137o rhodium alloy at

1300 K. The plotted values are averages of six meas ured values, three each on two specimens.

£

Q

O

K

<

.020

.018

0I«

0 14

0 I 2

0 10

.0 08

006

.004

002

“ i—r " i—I I I PLATINUM 13% RHODIUM AT 800 *K

I

- T~1

• OUE TO DIFFERENCES BETWEEN SPECIMENS

o DUE TO ERROR OF MEASUREMENT V"?."

J 15 6 7 8 9 10 II WAVELENGTH IN MICRONS

12 13 14 15

Fig. 5. Spectral distribution of two categories of

standard deviations, each computgd from six measured

emittance values obtained at 800 K, three each on two

specimens of platinum- 137, rhodium alloy. The upper

curve represents standard deviations due to differences in emittance between specimens, Identified as

ct8 in the text. The lower curve represents standard

deviations due to random error, identified as in

the text. In both curves each point represents the

moving average of five adjacent values.

12
E

s

i

Fig. 6. Spectral distribution of two categories of

standard deviations, each computed from six measured

emittance values obtained at 1100 K, three each on two

specimens of platinum- 13% rhodium alloy. The upper

curve represents standard deviations due to differences

in emittance between specimens, identified as cs in the

text. The lower curve represents standard deviations

due to random error, identified as c%, in the text. In

both curves each point represents the moving average of

five adjacent values.

t 020

|

0 1

8

~

(rt < .0 16 i

W .01 4 0

za

t

-012 1

UJ .0 10

I I

'

I

'

i I I 1 I PLATINUM 13% RHODIUM AT 1300 °K

• ®e

* DUE TO V

•DIFFERENCES

• BETWEEN SPECIMENS %

©

0 ®

|

.006

> .006-

004

.002

DUE TO ERROR OF MEASUREMENT

• ® it

,

8

3 „O°00Ch_ 0

CP

o o0 o° AxbO°

o<R>o

<ao«Xo

o 0

.1 .. i. 3 4 5 6 7 8 9 10 II WAVELENGTH IN MICRONS

12 13 14 15

Fig. 7. Spectral distribution of two categories of

standard deviations, each computed from six measured

emittance values obtained at 1300°K, three each on two

specimens of platinum- 13% rhodium alloy. The upper

curve represents standard deviations due to differences

in emittance between specimens, identified as as in the

text. The lower curve represents standard deviations

due to random error, identified as in the text. In

both curves, each point represents the moving average

of five adjacent values.

13
The increase in precision (lower am values) over what was obtained in

the tests on platinum reported in WADC TR 59-510 Pt IV can be ascribed in part

to the reduction in error due to direct recording of data by the data-processing attachment as compared to reading the curves with a variable scale.

B. Oxidized Inconel Working Standards

Specimens were cut from 2x8 inch Inconel sheet. Six strips, 1/4 x 8

inches in size were cut from the two edges of the sheet, three from each

edge. Twelve discs, 0.484-inch in diameter, were cut from the center of the

sheet. All specimens were marked for identification, and the position and

orientation of each specimen in the original sheet was recorded. The speci- mens were, sandblasted with 60-mesh fused alumina grit and an air pressure of

approximately 70 psi, care being taken to obtain a uniformly rough surface on all specimens. The sandblasted specimens were cleaned ul trasonical ly in acetone, passivated for one minute in 10% nitric acid at 316°K (43°C), rinsed in

distilled water and then in freshly distilled acetone. The cleaned specimens were subjected to a minimum of handling. When handling was unavoidable, rubber surgical gloves were worn, and the specimens were touched only by the ends

or edges

.

The strip specimens were suspended from a metal rack by means of oxidation-resistant metal hooks, and the rack was inserted into a cold furnace.

The disc specimens were supported by the edges only on special ceramic supports placed on the hearth of the furnace and enclosed in a ceramic muffle.

The furnace was brought to 1340°K (1067°C) and held for 24 hours, then dropped

to 1100°K (827°C) and held for an additional 24 hours, after which the speci- mens were allowed to cool in the furnace.

The specimens were removed from the furnace by means of cleaned stainless

steel tongs, and were placed in individual plastic holders, in which they

were supported by the ends or edges only. Each plastic holder, containing a specimen, was then placed in an individual cardboard box, to protect the speci- men against contamination.

The six 1/4 x 8 inch strips were prepared for measurement by welding a platinum-platinum 10% rhodium thermocouple to each specimen. A shallow groove

was scratched in each specimen near its mid length and normal to its axis,

which penetrated through the oxide coating to the bare metal. The oxide was also removed from each end of the specimen by grinding for a distance of approximately one inch from each end. The thermocouples were welded by a procedure similar to that used for the platinum- 13% rhodium specimens.

The normal spectral emittance of each of the six specimens was measured

three times at each of three temperatures, and the data were analyzed statistically, as in the case of the platinum- 13% rhodium specimens. The results

are shown in Table III and are plotted as a function of wavelength in figures

8 through 13.

14
Fig. 8. Normal spectral emittance of 0.484-inch disc

working standards of oxidized sandblasted Inconel at

800°K. The plotted values are averages of 18 measured values, three each on six specimens.

Fig. 9. Normal spectral emittance of 0.484-inch disc

working standards of oxidized sandblasted Inconel at

1100°K. The plotted vaues are averages of 18 measured values, three each on six specimens.

15
Fig. 10. Normal spectral emittance of 0.484-inch disc

working standards of oxidized sandblasted Inconel at

1300°K. The plotted values are averages of 18 measured values, three each on six specimens.

|

040

HI .03 6

i

U, .02®

.020

.016

3 012

006 ac

S 004

T T~~~\I I I I I I “T~

OXIDIZED INCONEL AT 800 °K -|

standard deviations, each computed from 18 measured

emittance values obtained at 800 K, three each on six

specimens of oxidized sandblasted Inconel. The upper

curve represents standard deviations due to differences

in emittance between specimens, identified as as in the

text. The lower curve represents standard deviations

due to random error, identified as am

in the text. In

both curves, each point represents the moving average

of five adjacent values.

16
H .040 i r z

u2 03 6 r E$ .032

UJS

uj .028 -

t

Zw .020

2 016 o

< 012

>£

.008 Q

CC<Q .004 2

<3

t—

i/)

i r i r T I--

OXIDIZED WGOMEL AT HOO *K

QStt>Cto o oooooo0 ® 0000^'’

13 _L

4 3 J L

0 9

$>«

1 1

10 II 12 13 J

14 15

Fig. 12.

S 7 WAVELENGTH IN MICRONS Spectral distribution of two categories of

standard deviations, each computed from 18 measured

emittance values obtained at 1100 K, three each on six

specimens of oxidized sandblasted Inconel. The upper

curve represents standard deviations due to differences

in emittance between specimens, identified as cjs in the

text. The lower curve represents standard deviations

due to random error, identified as amin the text. In

both curves, each point represents the moving average

of five adjacent values.

I" I I ! I I T 1 ] ~ K 040 I > I 2

UJw 036

a:"D 40< .032

UJ2

w .028 o

22 .02 4 K

2w .020

2

016 2

<012

>k

008 a

<z§ 004

So

"1

I

OXIDIZED INCONEL AT 1300 °K

>0000

o_

s

°o°o

I10

caxaxnxc^fp

12 13 14 15

Fig. 13

5 6 7 8 9 WAVELENGTH IN MICRONS Spectral distribution of two categories of

standard deviations, each computed from 18 measured

emittance values obtained at 1300°K, three each on six

specimens of oxidized sandblasted Inconel. The upper

curve represents standard deviations due to differences

in emittance between specimens, indentified as in the

text. The lower curve represents standard deviations

due to random error, identified as am

in the text. In

both curves, each point represents the moving average

of five adjacent values.

17
The general shape of the spectral emittance curves is similar to that

obtained on the previous standards, but the emittance at each wavelength is

somewhat higher. There was a slight increase in emittance with an increase

in temperature at each wavelength.

The values of airland a obtained at 800°K are plotted in figure 11,

at 1100 K in figure 12 and at 1300 K in figure 13.

In general the values of as were somewhat larger than those of am , and

showed greater variation with wavelength. The average values of am were

0.70 at 800°K, 0.59 at 1100°K and 0.63 at 1300°K and the corresponding values

of as were 0.82 at 800°K, 1.04 at 1100°K and 1.00 at 1300°K. This is a con- siderable improvement in reproducibility of specimens over what was obtained

in the tests reported in WADC TR 59-510 Pt IV, and is part due to the fact

that the specimens were cut from adjacent portions of the original sheet.

There is also some improvement in precision over the corresponding data

reported in WADC TR 59-510 Pt IV, which can again be ascribed to a reduction

in the reading error due to use of the data-processing attachment.

V. SPECTRAL REFLECTANCE EQUIPMENT

Equipment for measurement of spectral reflectance under conditions approximating normal illumination and hemispherical viewing was described in

WADC Technical Report 59-510, Parts II and III. The equipment utilizes a

12 in. diameter ellipsoidal mirror with the specimen placed at the first fo- cus and the detector at the second.

During the early part of last year, construction of a light-tight cover

for the equipment was completed permitting the convenience of operating the

equipment in normal room lighting. Additional modifications were made on the following features of the apparatus.

(1) Optical system - mounts were designed and constructed to

permit greater ease in alignment or adjustment of optical com- ponents .

(2) Specimen mount - a mounting jig was designed and constructed

to allow convenient removal or installation of specimens; the

specimen holders allowed measurements to be made at various fixed

angles of incidence.

(3) Detector mount - the method of mounting the detector was modified with a gear rack and pinion mechanism so that the detector

could be moved between the ellipsoid first and second focus points.

2_! See footnote 1 on page 10.

18
The principal effort in the past year has been directed toward improvement of the signal- to-noise ratio with the large area ( 1 cm diam.) Golay

cell detector. It was found that operation of the equipment during the wave- length scanning process did not yield data of the desired accuracy. The reason for the poor performance was traced to mechanical vibrations rather

than electronic malfunctions or deficiencies. To eliminate transmission of

air-borne vibration to the cell, the interior surfaces of the light-tight cover were covered with a 3/4" thick acoustic matting, and to reduce structure-borne energy transmission, the detector and mount were supported on an

800 pound seismic table which was independent of other parts of the equipment and rested on the floor. Figure 14 is a photograph of the modified

equipment. Despite these precautions to isolate the Golay detector from ex- ternal mechanical vibrations, the signal- to-noise ratio remained unacceptable. Because of these poor results it seemed desirable to investigate other

types of detectors. Two thermopile detectors with 1 cm

2 viewing areas have

been ordered and these will be tested in the near future.

Tests on a heated specimen (a white porcelain enamel) were conducted

using the Golay cell. The purpose of these tests were to determine the

background level of radiation emitted from the heated specimen that the detector could withstand without damage from excessive temperature. It was anticipated that the detector, because of its design, would not tolerate

any large temperature rise. However, quite surprisingly, the detector failed

when the specimen reached a temperature of only 70 C. Calculations indicated

that this corresponded to a background flux of about 500 microwatts. Such a result demonstrated that the Golay cell cannot be used in this equipment with

heated specimens and this again points to the need for another type of detector. During the coming year efforts will be directed toward obtaining

room- temperature reflectance data on various materials through use of the

large-area thermopiles.

VI. HIGH- TEMPERATURE INTEGRATING SPHERE REFLECTOMETER

The accuracy of a direct measurement of einittance depends primarily upon

the accuracy with which the temperatures of the specimen and blackbody are known. The percentage error in an emittance measurement that is due to the error in temperature measurement (or temperature difference between blackbody

and specimen) may be expressed as

dW>, = K

dT (4)

W\ T

where dW^ is the change in emitted energy, W4, accompanying a change in temperature, dT . The factor K may be evaluated from the expression

K =

CS /\T

C2 e

(5)

4T(ec2 //a -l)

where C2 is the second Planck radiation constant, e is the base of natural

^ logarithms, \ is wavelength and T is absolute temperature. At T = 0.29 cm K

which is the peak of the Planck distribution function, K = 5.0. At shorter

wavelengths, K increases rapidly with decreasing wavelength, and at longer

wavelengths, K decreases slowly with increasing wavelength.

19
Fig. 14. Photograph of the infrared ref lectometer with light cover panels

removed. The specimen is mounted at the first focus of the ellipsoidal

reflector and the detector at the second focus.

20
Thus it can be seen that the errors in direct emittance measurements are inherently large at short wavelengths, below the peak of the Planck distribution function. Also, accurate temperature (or temperature difference) measure- ments are difficult to make at temperatures above those at which conventional

thermocouples can be used, particularly on materials whose spectral emittance

at the optical pyrometer wavelength is not accurately known. As a result, er- rors in direct emittance measurements at such temperatures are inherently

large

.

In contrast to emittance, the accuracy of a reflectance measurement is

not affected by the accuracy with which temperature of the specimen is known.

Hence, reflectance measurements appear to offer inherently greater accuracy

than emittance measurements both at short wavelengths and at high temperatures.

Because of these apparent advantages of the reflectance approach, consideration has been given to the design of an integrating sphere ref lectometer

utilizing a continuous-wave gas laser as the illuminating source. The principal difficulty in making high- temperature spectral reflectance measurements

with conventional techniques and apparatus arises from the inability to detect

the dispersed AC (chopped) reflected radiation in the presence of a large flux

of DC (unchopped) undispersed radiation emitted by a heated specimen. Utilizing a gas laser as the source removes this experimental difficulty, since the

chopped flux reflected from the specimen can be of an intensity many orders of

magnitude larger than the flux emitted by the specimen. Consequently, the

precision with which the radiation detector can sense the reflected flux is

greatly increased and high-precision reflectance measurements at high temperatures should be possible. To be sure, there are disadvantages encountered in

utilizing the laser as a radiometric source, the principal one being that the

high- intensity output is available only at discrete wavelengths, making it impossible to obtain measurements over a continuous wavelength interval, as is

possible with conventional techniques. Notwithstanding this objection, it seems probable that this difficulty may at least be partially overcome by

future developments in laser technology.

Even if measurements can be made only at a relatively few discrete wavelengths, the data thus obtained will be valuable. Available evidence indicates that where no phase changes occur due to heating, the general shape of

the spectral reflectance curve of a material does not change appreciably with

an increase in temperature. Hence, it should be possible to interpolate between wavelengths with the aid of continuous spectral reflectance curves obtained at room temperature by more conventional methods.

The basic objectives of the work with lasers are three-fold:

(1) To investigate and evaluate the practicability of utilizing

the continuous -wave gas laser as a radiometric source.

(2) To develop techniques and apparatus for high-precision re- flectance measurements on specular and diffuse specimens at elevated temperatures and at discrete wavelengths.

21
(3) To investigate coatings and coating techniques for integrating

spheres that will permit operation with this method into the far infrared portion of the spectrum (from 3 to 15 microns or beyond)

.

There are many features of the continuous-wave gas laser in addition to

its high monochromacity and intensity that make the laser desirable as a radiometric source. The output can be electronically modulated (chopped),

removing the necessity for cumbersome mechanical chopping and rectifying

assemblies. Outputs are available using various gas combinations at high

intensities at discrete wavelengths in the spectral region 0.4 to 40(j..

These features - and others - will be given close scrutiny and, if possible,

the advantages will be exploited to further advance our abilities to make

thermal property measurements with greater accuracy, especially at the higher temperatures and the longer wavelengths.

One immediate need is for high-precision spectral data to further ad- vance the art of optical pyrometry. Recently developed optical pyrometers

are capable of high precision measurement of brightness temperatures. The

accuracy with which these brightness temperatures can be converted to true

temperatures, however, is dependent on a knowledge of emittances at 0.65p.

At present there is no gas system which will lase at this wavelength, but

by a series of measurements close to 0.65|i, it should be possible to use the

appropriate theoretical model to arrive, by interpolation, at an accurate

emittance at the optical pyrometer wavelength.

The integrating sphere technique for measurement of spectral data in

the visible and to 2.5|i is well established. Such a sphere is usually coated with smoked magnesitam oxide which has high reflectance (> 95%) in the

visible and near infrared, and is in addition a good diffuser of radiation.

The same coating is also used for a reflectance standard. Unfortunately no

such coating has been developed for integrating spheres operating at wavelengths longer than 2.5p. Flowers of sulphur is a possibility but more work

is needed. One of the principal goals in this phase of the program is to

select and evaluate a coating for an integrating sphere for use at long

wavelengths

.

.VII. EQUATIONS RELATING SPECTRAL EMISSIVITY

OT METALS TO OTHER PROPERTIES

A summary of the background and current status of this phase of the

work follows. Equations relating the emissivity of metals to their electrical resistivities have been available for many years. The earliest attempts

by Hagen and Rubens have been modified through the years to produce relations that are generally applicable in the longer wavelength and elevated

temperature regions. While this approach to prediction of properties has

been very successful for restrictive conditions, it is not satisfactory for

explaining the inflections and irregularities observed in experimental emissivity (reflectivity) data.

22
A more realistic approach to prediction of the property must consider

the mechanism of the transport process to be characterized by more than one family of free electrons. Recent publications by Roberts [l] and T. R. Harrison \ 2

~] have given equations that are applicable or adaptable, including the effects of several families of free and bound electrons on the

transport process. This classical approach is in harmony with quantum me- chanism, as electrons in different energy zones are shown to have different

behaviors

.

The equations suggested by Harrison, with terms to provide for the

effects of free and bound electron families, have been considered. Attempts

were made to compute good values of the equation parameters from reliable

normal spectral reflectivity values of the metal rhodium at room temperature.

As stated in a previous report, first only one category of free electrons

and one of bound were used. Within the wavelength range of visible radiation a curve obtained in this way gave a very creditable fit, and followed

the inflection corresponding to a maximum in emittance of about 0.45 micron.

In the attempt to extend the range of good fit out to about lOp, it became

evident that additional parameters, making at least 10 in all, would be re- quired for insertion into more than one term for free electrons and more

than one for bound electrons.

Work will continue on the rhodium data until parameters for proper

theory-data comparison can be better determined. Special consideration will

be given to the effect on the parameters of uncertainties in the reflectivity data. Optical constants determined from the parameters derived from re- flectivity data will be computed and examined to determine the physical

creditability of this approach.

With the fraction of total effort on this study that could be devoted

to this aspect, no set of parameters has yet been found that will produce

a normal spectral reflectivity curve which fits the observed data over a wide wavelength interval both generally and in detail. However the findings have not been negative and show promise that further exploration could

produce some useful results.

Several additional attempts to determine the proper parameters for the

theoretical expression using a different approach did not yield any significant results. It was found impossible to theoretically fit the experimental data in a general and detailed manner. Further study indicated that

the experimental reflectivity curve for rhodium might be at fault. Hence,

the sources of the rhodium reflectivity data were re-evaluated and several

inflection points were found to be caused by improper smoothing of data

that were obtained in different determinations. However, when these data

were readjusted, it was impossible to determine a set of parameters for the

HI Roberts, S. Phys Rev 100, 1667 (1955); 114, 104 (1959); 118, 1509(1960).

[2] Harrison, T. R. "Radiation Pyrometry and its Underlying Principles

of Radiant Heat Transfer" pp 28-62 and Appendix D. John Wiley & Sons

(1960) .

23
expression that provided a suitable match with the experimental curve. Optical constants (index of refraction and absorption coefficient) when com- puted from these parameters proved to be physically unrealistic. This led

to consideration of the Kramer s-Kr on ig dispersion relations which permits

calculation of the optical constants from knowledge of the reflectivity over the entire frequency (wavelength) spectrum. At present a computer program

is being developed which will perform these calculations. Further study of

this technique reveals that the shape of the reflectivity curve at very short

wavelengths (vacuum ultraviolet) is quite significant. It is also evident

that the shape of the curve (or optical activity) in this region makes an important contribution in the calculation of the optical constants in other

wavelength regions.

It is apparent that special consideration must be given to the reliability of the reflectivity at wavelengths in the ultra-violet and below. In

this region, the reflectivity is extremely sensitive to surface conditions.

This is a serious consequence since there is not always an abundance of data

in this region. This region is of primary significance to our study of optical behavior in other regions of the spectrum where there is a comparativelarge amount of reliable reflectivity data.

It is expected that work of this type will continue to be only a small

fraction of the total effort.

24
WAVELENGTHS

FOR

COMPUTATION

OF

TOTAL

EMITTANCE

FROM

SPECTRAL

DATA

BY

THE

100

-SELECTED

ORDINATE

METHOD

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Mf 00 CM r—

1

M> pH CO oo m CNI o 00 rv M0 MO r-. O' pH 00 CO CTo MO o m O' Mf 00 CO r^. CM MO pH MO rH in o HO O in o MO pH MO CM

Ui O' o o o t—

1

»—

1

CM CM CO CO vt vt in m M0 M> rv rv 00 00 O' O' o o o CM CO CO CO CO CO co CO co CO co CO CO co CO CO CO co CO <o co co Mf vt

zL

m m m m m in m in in m m m m m in m in m m m m UO m in MO 00 O' o v—

1

CM CO <t m MO 00 O' o rH CM co vt m MO rv 00 CTO

Is CM CM CM CM CO co CO CO co CO co no CO CO -t Mf Mf vt vt vt vt vt Mf 26
in

Microns

at

Temperature

in

°K

of

sO as «-H sO rH 00 sO X O'. X as X X as X O' X as uo rH CO X

o in O'. CO CO CNJ r- f-H sO f-H MO f-H X X CO Os in X X UO CM o X X <f co o ON as o o r-H f-H CM CM CO CO Mt <t in in X X r- X X as o pH pH CN CO Mt

r—

1

CM CM co co co CO CO CO CO CO X X X CO CO X X CO CO co Mt <t <3-

CM X CNJ 00 r- m in n- as CO X in Ml- X f-H X X X CN as O' CO rH CN X

o 00 CNI r-H X f—

H

X f-H sO CM r- co O' in f-H X pH X X CO pH o as X f\

o f-H X X CO CO <t vt in in MO X r^. X as as o pH pH CM CO Mt in in X

COH CO CO CO co CO CO CO co co CO X co co CO co CO Nt <t Mt <3" Mt <t <3*

m m in o Nt o in in n- o X X X in O' X pH X CO CN X

o cr\ as <3* o in f-H X CM X <t f-H f-H 00 in CO pH o X CN o <f x in x X OO O' as o rH t-H CM CO CO uo X r^. X as o pH CM • pH co X co co co co co co CO CO X <s- Mi- Mi- Mt Mt Mt <t Mt <t <$ X UO

o CO n- X O' X in X 00 CM r"- in <t in X X St X uo X co CM X CO r^. o in i-H sO X CO O' in r-H X rH X X CM o X X Mt co CM CM CM CM CO o CO 00 O' O' o O r-H CM CM CO <t in X X as o rH CN X Mt in X r-H

r—

H

X CO CO CO co <3* <f Mt <3* MS' Mt <fr -0 <1* Mt X X X in in in in

X <fr o in CM O o CNJ X X o pH X X pH Mt pH r-4 uo Nt X CM o CO as m r-H n- o T'- i-H X X X f—

H

O' X X Nf X X X pH o r—

1

f—

H

CNJ co CO m uo sO r^s. X O' o o r-H CNJ X X X X O' o X

opH <1- Mt <3" <1* <t vj* Nt <! in X m X X X X X X X X X X

X o co CO CO sO o sO X X X o o UO as C". X CO pH X X

as X X as x x o 00 in X f-H O' X X in X Mt Nt X X X o X X o

o x so n- 00 as o o r-H X X X X X X O' O pH CN co X X O' o

O' <t <f <3* Mt m in m X X X X in X in X X X X X SO X X X X

o Csi X' CM pH o r-H in o X X o in X Mf as X O' uo X pH pH X o as uo

r*^ Mt r-H O' n- in co pH o X r^. X X X X X o CM in X pH X o X

o r—

1

X CO CO in sO 00 X O' o f-H CM CO <t X X X as o pH CO NT X

o

00 X m m m m in uo in in X X X X X X X X X X X r^. r^.

O' CM co co CO sO CM O' as X r^. X CO X F"» Mt X O' r^. co X X

o Os SO in CO CO CM CNJ X co Mt X O' pH pH in o X CN O' o as as o pH CNJ CO <t* in MO X as o rH X CO X X r- as o CM CO UO X X

o

n- uo X X X in X X sO MO X X sO 1^- X X X X X X

co o o o in o 00 o CO X o co o o X X o X co X pH X X X X CO as O' O' as as o o CNJ CO X O' CNJ uo X X pH co o X Mt U0 o 00 O' o r-H CM Nt- m X X as o CM X X O' o CM Mt in as pH CO vO X SO x r^. r^- X X X X X X X O' as O' as as as o o pH pH

x <}* o in CM o o CNJ X X o f-H X CN pH pH pH in <t X X

CO Os m t-H r-- <3* o <3* r-H X X X pH as X UO Mt <t Mt ln X X r-H f-H r-H X CO CO m m MO r^. X O' o o rH CNJ CO in X X O' o CN

O Mt Mt Mt Mt Nt Mt Mt Nf X X X X X in in X in X UO X X

in m m in in m in in in X X in in in X X X X uo uo in X UO in in in o r-H CNI CO in sO 00 O' o rH CNJ X Mf X X X O' o rH CM co <1* X

•2 in m m in in m LO in X X X X X X X X X X X

27
in

Microns

at

Temperature

in

°K

of

H <<

Oo4oo

coO

CMooooooo

ONoo

00oo

r-oo

nO

H o ^ zL

pH o ««t

m CO eo CN CO 04 r^. rH NO ONm CO

m pH ON 00 CO On 00 o

co

m CO •4- nO oo CM nO Csl O' rx 00 o in 4 n*.

m rH NO n- CO CO 00 oo

in nO 00 O'- o 04 CO in no 00 o COm oo rHm o m CM CM NO o ON 4 4 4 >4 in m m m m in no NO NO NO rx I"-- 00 00 ON O rH 4 o rH rH pH CN

ON NO 00 00 in ON 4 o 00 o ON 00 rH 4 rH in NO n- 00 CM pHm CM <t

C*. 00 ON rH Nf CN 00 4 cn CM xt ON NO rx CM CO CN CN ON CM cn ix ON

oo ON o CM CO xt NO rx ON rH COm o CO rx rH nO CN ON

O

m rHm <1* xt IT) m m m in m in NO NO NO NO rx rx rx 00 00 O' ON O CM m CM

rH pH pH CN

NO rH CO CM

O NO CM rH CO pH NO rx CM NO NO CO

m NO

m ON O' NO NO

CO o CN in ON

m O' NO 4 xt in ON

m un 00 oo rH ON CM cn rx CO rx CM 4 m NO rx ON O CM xt NO 00 o cn NO ON cn 00 cn ON 00 O' m 4 xt

in

m in inm in NO NO NO NO NO rx ix r-» rx 00 00 ON ON

O rH CO NO xt

rH pH rH rH CM

NO CO

m NO NO

m NO rH ON in o ON NO 00 CNi ON

m in 00 O'

m rH CM NO ON CM NO rH rx xt CO CM 4 00 CO CM 4 pH CM rH ON IX o CM pH CO o

rx 00

O rH cn 4 NO 00 o CN 4 rx

O CO i--- pH NO rH 00 00

O 00 On rx UN in NO NO NO NO NO NO rx rx r-. rx 00 00 00 ON ON o o pH CO <t NO

rH pH rH rH pH pH C\i

cn CM 00 CO 00 CO pH xt CM ON 00 cn ON CO cn CM rx

m NO o IX

m xt CNJ 4 00 CN 00 4 CNJ rH rH CO NO CM rH CM 00 00 4 n- rH CN ON CM ON CM rx CO xt NO rx ON rH CO m rx O' CM m 00 rH m O m CM ON ON cn CM rx CO

NO nO

N

D

NO NO rx rx rx IX rx 00 00 00 ON O'

OO pH rH CN 4 NO ON ON

pH pH rH pH rH rH pH rH CM

00 CM rx o xt cn ON rH xt CM ON o CO 00 00 CM rH ON on ON

mm un 4 O nO CO CM rH CM an m xt in rH o xt in m NO CM CO rH o pH CO © CM CO m rx ON rH cn m CO rH 4 00 CN NO rH rx 4 cn xt ON rH ON NO

r-~ IX p" rx rx rx 00 00 CO 00 ON ON O' o o rH rH CM CO xtm 00 rH CM

rH rH rH pH rH rH pH rH rH CN CO

ON (M in O' un s

ON CMm pHm rH NO ON ON CM rH ON in 00 O' ONmm

CMO 00 IX 00 CO O' NO NO 00 cn rx IX un CM rH O'

m o NO un pH ON rH CM 4 NO ON rH CO NO O' CN o <t O' m CM o ON CM On CO NO IX rx 00 00 00 00 00 ON ON O' ON o o pH pH rH CN CO 4 4 NO rx o xt NO

pH rH rH rH rH rH rH rH rH rH rH CM CM CO

CM o ON o NO NO xt

m NO

m in CN cn ON o NO o CN IX 00 00 ON 00 rH NO NO NO ON CM xt cn 3

00

m NO rH rH ON rH CM COm NO r— rx nO o CN <t NO ON rH 4 IX CO r-^ pH NO rH NO CO rH o rH un 4 CN rH ON

ON ON ON ON ON o O o pH rH rH CN CM cn cn xt

m NO rx 00

O CO 00 rH

rH rH rH pH rH rH rH rH pH rH rH pH rH rH pH CM CM CM xt

pH CO NO 4 o pH un cn NO rH CN 00 4 xt pH NO 00 CO ON rx CM pH

r-~ o xt

O 00 00 CM CO 00 rH 00 pH o rx CO CM CM ON xt rx

m IX un

un 00 o cnm 00 rH in 00 CN rx pH i-" CO ON rx NOm ON NO 00 rH 00 O'

O o rH rH rH pH CM CM CM CO cn 4 4 m un NO rx 00 O' rH CO IX CM 00

pH rH rH rH rH rH rH rH rH «-H pH rH rH rH rH pH pH rH rH CM CN CM CO <t

U

C()

03

>-i doooco4J

cO •H

TO

cOU

Jn T3O

-QXO

CO H

JO

4-4OO

00

cO

4-1 d0) od

<ua

T3

a)

cOo

TOC

cO -d

4J

T3

aj U

COo

*r4 TOd

O

COd

<uCOo

-do oX4Jd

cO d4J

CO

d

r-4 <U << do

-d ^ 4-J CO 00d oo CO CM 00 CO 00 CO rH xt Cn! ON 00 cn ON cn cn CM rx un NO o rx un 4 CM <U £

xt 00 CN 00 4 CM rH pH CO NO CM pH CN 00 CO 4 rH ON ON CM ON CM rx pH 4-J CO xt NO rx ON pH cn m rx ON CM m 00 rH m O un CM ON ON CO CM rx CO 0) 00 NO NO NO nO NO i--. i-- r-» rx r-. 00 00 00 ON ON O O rH pH CN 4 NO ON <ys > d

pH rH pH pH pH pH rH pH CN aj <u 5 rH

a> o >

x.

d

un un un

m un un unm un in in un in un

m

mm un unm in unm in

H

NO rx 00 ON o rH CM CO 4 in NO rx 00 O' o pH CM cn 4 un NO rx 00 ON

rx rx IX IX 00 00 00 CO GO 00 00 00 00 oo O' ON ON ON ON On ON ON ON ON

H

28
TABLE II

NORMAL SPECTRAL EMITTANCE OF

PLATINUM RHODIUM WORKING STANDARDS AT 800 °K

Wavelength Emittance^ 2/ 2 ^s~

Microns X100 X100 X100

1.18 24.2 .16 .19

1.25 25.5 .49 .26

1.33 26.1 .29 .94

1.40 26.2 .30 .90

1.48 25.2 .15 1.06

1.58 23.7 .23 .97

1.68 22.1 .30 .78

1.81 20.6 .18 .73

1.98 19.2 .24 .64

2.23 17.7 .36 .42

2.51 16.5 .34 .33

2.73 15.4 .29 .26

2.92 14.7 .29 .07

3.14 13.8 .38 .05

3.35 13.2 .27 .07

3.56 12.6 .20 .14

3.77 12.2 .20 .26

3.98 11.7 .16 .19

4.20 11.3 .15 .38

4.41 11.0 .33 .14

4.58 10.8 .26 .19

4.76 10.5 .27 .19

4.91 10.2 .23 .31

5.07 10.1 .23 .35

5.21 9.9 .20 .21

5.34 9.7 .27 .31

5.47 9.7 .17 .42

5.60 9.5 .22 .40

5.76 9.3 .22 .40

5.90 9.1 .09 .45

6.04 8.9 .15 .40

6.16 8.7 .20 .35

6.28 8.7 .15 .28

6.41 8.6 .16 .31

6.53 8.6 .21 .24

29
TABLE II cont'd.

NORMAL SPECTRAL EMXTTANCE OF

PLATINUM RHODIUM WORKING STANDARDS AT 800 °K

Wavelength _ J 1/ Emittance- 2/ 2/

Microns X100 X100 X100

6.64 8.5 .33 .31

6.76 8.4 .22 .33

6.87 8.4 .16 .38

6.97 8.4 .21 .42

7.07 8.4 .20 .28

7.19 8.3 .21 .40

7.32 8.2 .18 .47

7.44 8.2 .15 .40

7.56 8.1 .19 .45

7.66 8.0 .12 .49

7.77 8.0 .20 .33

7.88 7.9 .21 .35

7.98 7.9 .15 .35

8.08 7.9 .23 .33

8.18 7.8 .23 .26

8.28 7.8 .24 .28

8.38 7.9 .24 .33

8.47 8.0 .31 .12

8.57 8.0 .22 .19

8 . 66 8.0 .23 .26

8.75 8,1 .22 .14

8.84 8.1 .26 .16

8.93 8.1 .17 .24

9.01 8.0 .13 .12

9.10 8.0 .18 .19

9.18 8.1 .23 .33

9.26 8.1 .24 .16

9.35 8.6 .25 .02

9.43 9.1 .25 .02

9.51 9.4 .13 .05

9.67 9.3 .16 .26

9.83 8.6 .31 ,21

10.00 8.1 .14 .19

10.15 7.8 .24 .19

10.30 7.6 .24 .19

30
TABLE II cont'd.

NORMAL SPECTRAL EMITTANCE OF

PLATINUM RHODIUM WORKING STANDARDS AT 800 °K

Wavelength 1/ Emittance - 2/

°m

2

Microns X100 X100 X100

10.46 7.3 .23 .07

10.61 7.2 .31 .14

10.76 7.1 .15 .09

10.91 7.0 .34 .14

11.05 7.0 .29 .16

11.19 6.9 .23 .24

11.32 6.8 .25 .16

11.45 6.8 .18 .05

11.58 6.6 .30 .16

11.72 6.6 .14 .14

11.84 6.5 .19 .09

11.97 6 .

6

.24 .26

12.09 6.4 .39 .21

12.22 6.5 .20 .12

12.35 6.4 .22 .12

12.48 6.4 .24 .12

12.60 6.2 .18 .12

12.72 6.2 .16 .09

12.85 6.2 .20 .16

12.98 6.2 .17 .19

13.10 6.2 .18 .09

13.22 6.2 .23 .05

13.34 6.0 .30 .09

13.46 6.0 .23 .05

13.58 6.0 .19 .09

13.69 5.9 .23 .09

13.81 5.9 .28 .12

13.93 5.8 .17 .07

14.03 5.8 .32 .26

14.14 5.8 .30 .24

14.25 5.7 .26 .21

14.36 5.7 .27 .19

14.47 5.7 .22 .14

14.58 5.6 .41 .09

14.68 5.5 .31 .09

31
TABLE II cont'd.

NORMAL SPECTRAL EMITTANCE OF

PLATINUM RHODIUM WORKING STANDARDS AT 800 °K

Wavelength Emittance—

_ 2/

^m

2 *8“

Microns X100 X100 X100

14.79 5.6 .27 .02

14.90 5.6 .33 .07

15.01 5.7 .22 .02

15.11 5 .

6

.26 .07

1/ Average of 6 measured values, three each on two specimens.

2/ See footnote 1 on page 3 in the text.

32
TABLE II cont'd.

NORMAL SPECTRAL EMITTANCE OF

PLATINUM RHODIUM WORKING STANDARDS AT 1100°K

1 / 2 / 2 /

Wavelength Emittanc£" °m

Microns X100 X100 X100

1.07 23.1 .45 .14

1.12 23.3 .47 .24

1.18 23.1 .48 .02

1.25 22.5 .56 .14

1.33 22.3 .50 .24

1.40 21.8 .39 .09

1.48 21.3 .37 .02

1.58 20.7 .37

1.68 20.0 .34 .02

1.81 19.1 .29 .07

1.98 18.5 .26 .16

2.23 17.7 ,29 .21

2.51 16,8 .24 .16

2.73 16.1 .17 .14

2.92 15.7 .22 .38

3.14 15.0 .27 .54

3.35 14.6 .34 .61

3.56 14.2 .38 .61

3.77 13.9 .34 .94

3.98 13.5 .35 1.11

4.20 13.1 .23 1.06

4.41 12.7 .16 1.15

4.58 12.5 .16 1.11

4.76 12.2 .21 1.13

4.91 12.0 .21 1.13

5.07 11.8 .10 1.13

5.21 11.6 .14 1.23

5.34 11.4 .20 1.15

5.47 11.2 .18 1.18

5.60 11.0 .24 1.30

5.76 10.9 .13 1.15

5.90 10.7 .12 1.06

6.04 10.5 .18 .97

6.16 10.5 .13 .94

6.28 10.4 .13 .94

33
TABLE II cont'd.

NORMAL SPECTRAL EMITTANCE OF

PLATINUM RHODIUM WORKING STANDARDS AT 1100°K

Wavelength „ , 1/ Emittance

2/

°m

2/

CT s Microns X100 X100 X100

6.41 10.3 .18 .99

6.53 10.1 .12 .75

6.64 10.0 .17 .80

6.76 9.8 .18 .78

6.87 9.8 .08 .94

6.97 9.6 .14 .94

7.07 9.6 .13 1.08

7.19 9.5 .22 1.04

7.32 9.5 .17 .99

7.44 9.4 .18 1.01

7.56 9.4 .20 1.01

7.66 9.3 .15 .97

7.77 9.2 .15 .94

7.88 9.2 .09 .92

7.98 9.1 .13 .94

8.08 9.0 .19 .90

8.18 9.1 .19 .90

8.28 9.1 .15 .80

8.38 9.0 .09 .82

8.47 9.1 .08 .90

8.57 9.2 .12 .78

8 . 66 9.2 .11 .87

8.75 9.3 .08 .75

8.84 9.2 .15 .73

8.93 9.2 .06 .73

9.01 9.3 .11 .68

9.10 9.3 .08 .61

9.18 9.2 .12 .64

9.26 9.2 .16 .66

9.35 9.3 .15 .68

9.43 9.7 .11 .73

9.51 10.0 .18 .52

9.67 10.2 .07 .42

9.83 9.8 .12 .31

10.00 9.4 .19 .31

34
TABLE

NORMAL SPECTRAL EMITTANCE OF

PLATINUM RHODIUM WORKING STANDARDS AT liOO°K

Wavelength Emittance—

2/

°in 2 ,

Microns X100 X100 X100

10.15 9.0 .31 .35

10.30 8.6 .20 .28

10.46 8.4 .24 .54

10.61 8.4 .20 .52

10.76 8.2 .10 .42

10.91 8.1 .19 .40

11.05 8.0 .19 .38

11.19 7.8 .14 .38

11.32 7.8 .15 .54

11.45 7.7 .11 .61

11.58 7.6 .14 .54

11.72 7.5 .21 .45

11.84 7.4 .16 .33

11.97 7.4 .15 .47

12.09 7.3 .06 .40

12.22 7.3 .08 .38

12.35 7.2 .15 .42

12.48 7.2 .10 .49

12.60 7.2 .08 .38

12.72 7.1 .08 .26

12.85 7.0 .17 .26

12.98 7.0 .11 .24

13.10 6.9 .11 .38

13.22 6.9 .04 .16

13.34 6.9 .17 .21

13.46 6.9 .13 .19

13.58 6.8 .08 .05

13.69 6.8 .09 .14

13.81 6.7 .13 .16

13.93 6.8 .11 .26

14.03 6.6 .22 .19

14.14 6 .

6

.14 .21

14.25 6.5 .22 .05

14.36 6.5 .20 .31

14.47 6.4 .19 .19

35
TABLE II cont'd.

NORMAL SPECTRAL EMITTANCE OF

PLATINUM RHODIUM WORKING STANDARDS AT 1100°K

Wavelength _ J 1/ Emit tance

2/

CTm

2/

cr s Microns X100 X100 X100

14.58 6.5 .16 .12

14.68 6.5 .22 .28

14.79 6.5 .17 .19

14.90 6 .4 .14 .19

15.01 6.4 .25 .21

15.11 6.4 .37 .31

1 / Average of 6 measured values, three each on two specimens.

2 / See footnote 1 on page 3 in the text.

36
TABLE II cont'd.

NORMAL SPECTRAL EMITTANCE OF

PLATINUM RHODIUM WORKING STANDARDS AT 1300°K

Wavelength

1/

Emittance

2/ 2/

Microns X100 X100 X100

1.07 25.4 1.07 .28

1.12 25.2 .94 .14

1.18 24.7 .87 .02

1.25 24.3 .68 .12

1.33 23.7 .43

1.40 23.1 .40 .02

1.48 22.6 .30 .02

1.58 22.0 .29 .19

1 . 68 21.2 .24 .28

1.81 20.4 .43 .19

1.98 19.7 .29 .38

2.23 18.7 .39 .40

2.51 18.0 .41 .57

2.73 17.3 .32 .57

2.92 16.6 .23 .59

3.14 16.2 .21 .75

3.35 15.9 .16 .97

3.56 15.3 .15 .87

3.77 15.0 .23 1.06

3.98 14.6 .26 1.11

4.20 14.4 .25 1.18

4.41 14.0 .23 1.30

4.58 13.8 .26 1.53

4.76 13.7 .31 1.65

4.91 13.3 .23 1.72

5.07 13.2 .26 1.81

5.21 12.9 .27 1.77

5.34 12.8 .18 1.74

5.47 12.7 .18 1.74

5.60 12.5 .19 1.65

5.76 12.3 .25 1.70

5.90 12.1 .21 1.60

6.04 11.9 .25 1.63

6.16 11.6 .29 1.60

6.28 11.6 .31 1.65

37
TABLE II cont'd.

NORMAL SPECTRAL EMITTANCE OF

PLATINUM RHODIUM WORKING STANDARDS AT 1300°K

Wavelength _ , 1/ Emittance

2/ 2

Microns X100 X100 X100

6.41 11.6 .36 1.86

6.53 11.3 .38 1.67

6.64 11.2 .29 1.63

6.76 11.1 .38 1.65

6.87 11.0 .27 1.65

6.97 10.9 .22 1.65

7.07 10.8 .20 1.56

7.19 10.8 .15 1.46

7.32 10.7 .13 1.60

7.44 10.7 .22 1.56

7.56 10.6 .18 1.58

7.66 10.4 .28 1.63

7.77 10.4 .24 1.53

7.88 10.4 .13 1.53

7.98 10.4 .25 1.63

8.08 10.4 .27 1.60

8.18 10.3 .29 1.44

8.28 10.3 .19 1.39

8.38 10.2 .19 1.48

8.47 10.2 .20 1.46

8.57 10.2 .15 1.34

8.66 10.2 .17 1.37

8.75 10.2 .17 1.41

8.84 10.3 .19 1.32

8.93 10.2 .17 1.34

9.01 10.3 .18 1.34

9.10 10.2 .22 1.23

9.18 10.2 .15 1.18

9.26 10.2 .15 1.18

9.35 10.2 .16 1.30

9.43 10.2 .13 1.25

9.51 10.5 .10 1.20

9.67 10.9 .12 1.06

9.83 11.0 .10 .99

10.00 10.5 .12 1.06

38
TABLE II cont'd.

NORMAL SPECTRAL EMITTANCE OF

PLATINUM RHODIUM WORKING STANDARDS AT 1300°K

Wavelength

_ . 1/ Emittance ~ 2/ am - 2 <*s"

Microns X100 X100 X100

10.15 10.0 .27 1.04

10.30 9.7 .20 .92

10.46 9.5 .33 1.04

10.61 9.2 .15 .97

10.76 9.1 .15 .97

10.91 9.0 .08 .75

11.05 8.9 .12 .78

11.19 8.8 .16 .85

11.32 8.7 .25 .80

11.45 8.5 .09 .85

11.58 8.5 .09 .73

11.72 8.4 .17 .71

11.84 8.3 .14 .66

11.97 8.2 .19 .59

12.09 8.0 .20 .68

12.22 8.1 .09 .57

12.35 8.0 .15 .57

12.48 7.9 .13 .47

12.60 7.8 .20 .45

12.72 7.8 .16 .21

12.85 7.7 .15 .24

12.98 7.6 .14 .28

13.10 7.5 .11 .19

13.22 7.5 .17 .26

13.34 7.5 .28 .33

13.46 7.4 .19 .05

13.58 7.3 .17 .21

13.69 7.2 .12 .16

13.81 7.3 .15 .02

13.93 7.3 .15 .16

14.03 7.2 .18 .16

14.14 7.2 .16 .02

14.25 7.2 .13 .05

14.36 7.1 .11 .02

14.47 7.2 .16

39
TABLE II cont'd.

NORMAL SPECTRAL EMITTANCE OF

PLATINUM RHODIUM WORKING STANDARDS AT 1300°K

Wavelength

1/

Emittance

2/

CTm

2/

cr s Microns X100 X100 xioo

14.58 7.0 .16 .09

14.68 7.2 .21 .07

14.79 7.1 .16 .05

14.90 7.0 .23 .07

15.01 7.2 .19

15.11 7.2 .18 .05

1/ Average of 6 measured values, three each on two specimens.

27 See footnote 1 on page 3 in the text.

40
TABLE III

NORMAL SPECTRAL EMITTANCE OF

OXIDIZED INCONEL WORKING STANDARDS AT 800°K

Wavelength

1/

Emittance

2/

CTm

2

(7 ~

a Microns X100 X100 X100

1.18 82.0 .77 1.84

1.25 83.5 .88 1.19

1.33 84.5 .97 1.53

1.40 85.1 .70 1.67

1.48 85.1 .82 1.59

1.58 84.7 .85 1.50

1.68 84.2 .58 1.60

1.81 83.9 . 66 1.55

1.98 83.5 1.07 1.66

2.23 84.5 .81 1.22

2.51 83.3 .81 .98

2.73 83.2 .85 .88

2.92 82.8 .83 .88

3.14 82.7 .66 .78

3.35 82.6 .56 .73

3.56 82.5 .56 .75

3.77 82.4 .63 .76

3.98 82.1 .70 .89

4.20 82.1 .58 .93

4.41 82.1 . 66 .76

4.58 82.1 .68 .65

4.76 81.9 .50 .61

4.91 81.7 .67 .64

5.07 81.6 .80 .39

5.21 81.7 .77 .45

5.34 81.6 .93 .52

5.47 81.6 .85 .52

5.60 81.5 .87 .55

5.76 81.3 .72 .64

5.90 81.3 .66 .67

6.04 81.3 .81 .58

6.16 81.1 .65 .58

6.28 81.1 .83 .48

6.41 81.1 .66 .55

6.53 81.1 .63 .57

41
TABLE HI cont 'd.

NORMAL SPECTRAL EMITTANCE OF

OXIDIZED INCONEL WORKING STANDARDS AT 800°K

Wavelength Emittance —

°*r'

Microns X100 X100 X100

6.64 81.1 .65 .49

6.76 81.3 .63 .47

6.87 81.5 .62 .47

6.97 81.8 .76 .55

7.07 82.1 .70 .49

7.19 82.8 1.40 .80

7.32 82.8 .55 .59

7.44 83.1 .73 .60

7.56 83.3 .66 .61

7.66 83.6 .64 .56

7.77 83.9 .67 .60

7.88 84.2 .66 .61

7.98 85.0 .62 .66

8.08 85.9 .67 .60

8.18 86.5 .67 .62

8.28 87.1 .62 .64

8.38 87.5 .57 .65

8.47 87.5 .70 .75

8.57 87.7 .66 .80

8.66 87.9 .70 .84

8.75 88.1 .81 .95

8.84 88.2 .67 .88

8.93 88.4 .61 .92

9.01 88.4 1.60 1.15

9.10 88.9 1.04 .83

9.18 89.1 .73 .80

9.26 89.3 .78 .83

9.35 89.4 .72 .82

9.43 89.2 *‘68 .73

9.51 88.8 .73 .76

9.67 88.4 .68 .82

9.83 88.3 .67 .8©

10.00 88.3 .68 .72

10.15 88.6 .60 .75

10.30 88.9 .50 .82

42
TABLE III cont'd.

NORMAL SPECTRAL EMITTANCE OF

OXIDIZED INCONEL WORKING STANDARDS AT 800°

K

Wavelength Emittance—

m

2

tfs - Microns X100 XI 00 X100

10.46 89.4 .56 .84

10.61 89.5 .78 .98

10.76 89.7 .74 .93

10.91 90.0 .57 .74

11.05 90.2 .73 .71

11.19 90.5 .57 .81

11.32 90.6 .64 .81

11.45 90.7 .79 .87

11.58 90.8 .67 .85

11.72 91.1 .67 .75

11.84 91.3 .65 .67

11.97 91.5 .57 .78

12.09 91.6 .68 .81

12.22 91.8 .77 .76

12.35 92.0 .70 .77

12.48 92.4 .64 .80

12.60 92.9 .60 .89

12.72 93.0 .65 .95

12.85 93.3 .68 .89

12.98 93.4 .55 .80

13.10 93.8 .52 .83

13.22 94.1 .53 .79

13.34 94.2 .59 .81

13.46 94.3 .59 .90

13.58 94.4 .59 .84

13.69 94.3 .61 .86

13.81 94.0 .61 .80

13.93 93.3 .53 .85

14.03 91.7 .59 .85

14.14 89.8 .67 .82

14.25 87.6 .69 .86

14.36 85.2 .79 .91

14.47 82.8 .79 .92

14.58 80.5 .74 .92

14.68 78.2 .70 .87

43
TABLE III cont 'd.

NORMAL SPECTRAL EMITTANCE OF

OXIDIZED INCONEL WORKING STANDARDS AT 800°K

Wavelength Emi ttance~^ *2

Microns X100 X100 X100

14.79 75.9 .72 .91

14.90 73.9 .61 .84

15.01 72.3 .79 .89

15.11 70.8 .57 .89

1/ Average of 18 measured values, three each on six specimens.

2J See footnote 1 on page 3 in the text.
TABLE III cont'd.

NORMAL SPECTRAL EMITTANCE OF

OXIDIZED INCONEL WORKING STANDARDS AT 1100°K

Wavelength Emittance—

2/

CT sMicrons X100 X100 X100

1.07 89.4 1.10 3.13

1.12 89.5 .80 3.28

1.18 89.4 .76 3.17

1.25 89.3 .59 3.17

1.33 89.1 .57 2.87

1.40 88.9 .55 2.75

1.48 88.6 .66 2.51

1.58 88.1 .70 2.31

1.68 87.7 .77 2.05

1.81 87.4 .59 1.69

1.98 86.9 .50 1.61

2.23 86.7 .52 1.43

2.51 86.3 .55 1.53

2.73 85.7 .59 1.44

2.92 85.5 .60 1.48

3.14 85.4 .52 1.41

3.35 85.2 .53 1.36

3.56 85.0 .53 1.36

3.77 84.9 .58 1.25

3.98 84.8 .59 1.19

4.20 84.6 .66 1.11

4.41 84.5 .52 .92

4.58 84.4 .55 1.01

4.76 84.4 .60 .97

4.91 84.2 .81 1.32

5.07 84.3 .60 1.22

5.21 84.4 .63 1.17

5.34 84.5 .56 1.10

5.47 84.6 .53 1.11

5.60 84.5 .54 .97

5.76 84.0 1.21 1.45

5.90 83.9 .97 1.12

6.04 84.0 .78 .97

6.16 83.8 .69 .87

6.28 83.9 .54 .90

45
TABLE III cont'd.

NORMAL SPECTRAL EMITTANCE OF

OXIDIZED INCONEL WORKING STANDARDS AT 1I00°K

Wavelength Emittance—

2/ 2/

°s~

Microns X100 X100 X100

6.41 84.0 .61 .93

6.53 83.9 .51 .95

6.64 84.0 .51 .99

6.76 84.2 .57 .99

6.87 84.6 .64 1.03

6.97 84,8 .52 .95

7.07 85.0 .55 .91

7.19 85.2 .53 .87

7.32 85.3 .47 .80

7.44 85.4 .46 .70

7.56 85.6 .44 .67

7.66 85.7 .50 .60

7.77 86.0 .50 .69

7.88 86.2 .57 .67

7.98 86.7 .51 .77

8.08 87.1 .49 .74

8.18 87.6 .51 .56

8.28 88.0 .62 .54

8.38 88.4 .49 .59

8.47 88.6 .53 .56

8.57 88.7 .62 .48

8.66 88.9 .50 .51

8.75 88.9 .57 .45

8.84 89.0 .64 .51

8.93 89.3 .46 .50

9.01 89.4 .42 .60

9.10 89.5 .43 .65

9.18 89.7 .38 .73

9.26 89.8 .44 .74

9.35 89.9 .47 .72

9.43 90.0 .49 .62

9.51 90.0 .62 .47

9.67 89.8 .58 .27

9.83 89.9 .50 .33

10.00 89.9 .53 .44

46
TABLE III cont 'd.

NORMAL SPECTRAL EMITTANCE OF

OXIDIZED INCONEL WORKING STANDARDS AT 1100°K

Wavelength Emittance—

n y°m

2 as“

Microns X100 X100 X100

10.15 90.0 .39 .48

10.30 90.1 .39 .49

10.46 90.2 .47 .45

10.61 90.4 .54 .48

10.76 90.7 .46 .65

10.91 90.9 .38 .71

11.05 91.2 .43 .60

11.19 91.4 .42 .45

11.32 91.6 .47 .33

11.45 91.6 .54 .37

11.58 91.9 .50 .42

11.72 92.1 .37 .53

11.84 92.2 .33 .53

11.97 92.3 .58 .47

12.09 92.5 .57 .41

12.22 92.7 .59 .45

12.35 93.0 .59 .43

12.48 93.2 .52 .53

12.60 93.5 .44 .65

12.72 93.7 .48 .62

12.85 93.8 .53 .57

12.98 94.0 .61 .55

13.10 94.4 .56 .52

13.22 94.9 .62 .71

13.34 95.1 .51 .77

13.46 95.3 .51 .70

13.58 95.4 .63 .64

13.69 95.4 .71 .67

13.81 95.4 .59 .62

13.93 95.4 .46 .71

14.03 95.3 .38 .94

14.14 94.8 .37 1.11

14.25 93.8 .42 1.16

14.36 92.4 .66 1.44

14.47 90.9 .70 1.52

47
TABLE III cont'd.

NORMAL SPECTRAL EMITTANCE OF

OXIDIZED INCONEL WORKING STANDARDS AT 1100°K

Wavelength _ J 1/ Emittance - 2/

CTm

2/

as ~

Microns X100 X100 X100

14.58 89.1 .58 1.57

14.68 87.3 .53 1.65

14.79 85.4 .48 1.80

14.90 83.3 .49 1.89

15.01 81.3 .63 2.04

15.11 80.3 4.68 3.36

!_/ Average of 18 measured values, three each on six specimens.

2/ See footnote 1 on page 3 in the text.

48
TABLE III cont'd.

NORMAL SPECTRAL EMITTANCE OF

OXIDIZED INCONEL WORKING STANDARDS AT 1300°K

Wavelength Emittance"^

2/

CTm~ s Microns X100 X100 X100

1.07 91.7 1.57 2.87

1.12 91.4 1.59 2.68

1.18 91.2 1.45 2.52

1.25 91.0 1.63 2.37

1.33 90.8 1.53 2.10

1.40 90.4 1.22 1.90

1.48 89.8 1.26 1.71

1.58 89.4 1.13 1.57

1.68 88.8 .96 1.57

1.81 88.3 .88 1.45

1.98 87.9 .72 1.46

2.23 87.4 .93 1.38

2.51 86.9 1.15 1.53

2.73 86.5 .83 1.21

2.92 86.3 .83 1.15

3.14 86.1 .84 1.01

3.35 86.0 .72 .94

3.56 86.0 .71 .96

3.77 86.0 .63 .94

3.98 86.0 .66 .79

4.20 85.8 .42 .84

4.41 85.7 .67 .91

4.58 85.7 .73 .85

4.76 85.6 .54 .74

4.91 85.6 .54 .74

5.07 85.6 .49 .71

5.21 85.6 .61 .77

5.34 85.6 .61 .79

5.47 85.6 .63 .83

5.60 85.6 .65 .79

5.76 85.5 .75 .86

5.90 85.4 .49 .80

6.04 85.5 .53 .79

6.16 85.5 .56 .81

6.28 85.6 .31 .81

49
TABLE III cont'd.

NORMAL SPECTRAL EMITTANCE OF

OXIDIZED INCONEL WORKING STANDARDS AT 1300°K

Wavelength J 1/ Emittance- m

a y9 Microns X100 XI 00 X100

6.41 85.7 .38 .80

6.53 85.7 .63 .71

6.64 85.7 .51 .68

6.76 85.8 .56 .69

6.87 86.0 .52 .77

6.97 86.1 .60 .69

7.07 86.1 .59 .75

7.19 86.3 .70 .69

7.32 86.5 .71 .68

7.44 86.7 .65 .88

7.56 86.9 .58 .87

7.66 87.0 .61 .95

7.77 87.3 .45 .97

7.88 87.5 .42 .88

7.98 87.7 .37 .85

8.08 88.0 .40 .79

8.18 88.2 .54 .67

8.28 88.4 .42 .65

8.38 88.8 .36 .62

8.47 89.4 1.05 .66

8.57 89.4 .64 .55

8.66 89.5 .64 .55

8.75 89.6 .59 .61

8.84 89.7 .56 .66

8.93 89.8 .56 .67

9.01 90.0 .49 .82

9.10 90.1 .58 .76

9.18 89.9 .98 .98

9.26 90.2 .68 .76

9.35 90.3 .51 .77

9.43 90.3 .57 .80

9.51 90.4 .69 .79

9.67 90.6 .99 .72

9.83 90.4 .89 .71

10.00 90.3 .83 .72

50
TABLE III cont'd.

NORMAL SPECTRAL EMITTANCE OF

OXIDIZED INCONEL WORKING STANDARDS AT 1300°K

Wavelength „ !/ Emittance- a

if m

a if

s Microns X100 X100 X100

10.15 90.4 .72 .79

10.30 90.5 1.38 .93

10.46 90.8 .79 .79

10.61 90.9 1.36 .95

10.76 91.0 .54 .82

10.91 91.2 .55 .61

11.05 91.4 .59 .81

11.19 91.7 .50 .84

11.32 92.0 .54 .78

11.45 92.1 .58 .71

11.58 92.2 .47 . 66

11.72 92.3 .58 .83

11.84 92.6 .53 .80

11.97 92.9 .51 .72

12.09 93.0 .56 .72

12.22 93.2 .52 .62

12.35 93.3 .54 .69

12.48 93.6 .51 .76

12.60 93.9 .45 .70

12.72 94.3 .38 .72

12.85 94.4 .48 .72

12.98 94.7 .74 .59

13.10 94.9 .60 .57

13.22 95.1 .52 .64

13.34 95.5 .67 .68

13.46 95.6 .40 .67

13.58 95.8 .50 .59

13.69 95.8 .57 .64

13.81 96.0 .85 .56

13.93 96.0 .50 .63

14.03 95.8 .46 .62

14.14 95.5 .53 .75

14.25 94.9 .62 .88

14.36 94.0 1.13 1.06

14.47 93.1 .79 1.40

51
TABLE III cont'd.

NORMAL SPECTRAL EMITTANCE OF

OXIDIZED INCONEL WORKING STANDARDS AT 1300°K

Wavelength Emittance^ 2/ am~ s Microns X100 X100 X100

14.58 91.9 1.09 2.00

14.68 90.1 1.01 2.09

14.79 88.4 1.04 2.28

14.90 86.4 .99 2.51

15.01 84.5 1.07 2.57

15.11 82.7 1.05 2.73

1_/ Average of 18 measured values, three each on six specimens.

2/ See footnote 1 on page 3 in the text.

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