UAH RESEARCH REPORT NO. 475

Final Reoort

DROP TUBE TECHNICAL TASKS

(NASA-CE-178741) DEOP TUBE TECHNICAL TASKS

Pimal Report (Alabama Dniv. , HUBtsville.)

44 p HC fl03/MF A01 CSC1 14

N86-21564

Uuclas

63/12 16596

Kenneth E. Johnson

Environmental and Energy

Center

The University

Of Alabama

In Huntsville

January 19G6
UAH Research Report No. 475

Final Report

DROP TUBE TECHNICAL TASKS

Submitted to

NATIONAL AERONAUTICS AND SPACE ADMINISTRATION

George C. Marshall Space Flight Center

Marshall Space Flight Center, Alabama

Contract No. NAS8-35665

Submitted by

L Gar)£/L. Workman, PhD

Principal Investigator

Johnson Environmental and Energy Center

The University of Alabama in Huntsville

Huntsville, AL 35899

January 1986
Acknowledgements

I appreciate the efforts of many persons in the performance of this

work. In particular, Dr. William F. Kaukler, who was extremely helpful in

performing the metallurgical aspects of this project and for his leadership

in performing the drops. Steve Straits and his colleagues at the Drop Tube

did an exceptional job of getting drops whenever possible. Also to Dr. Ed

Etheridge for his efforts as technical contract monitor.
I. Introduction

The Drop Tube Facility at Marshall Space Flight Center is a

national asset used for studying a variety of solidification phenomena in a

low gravity environment or as a containerless processing system. By .virtue

of the relatively short turn around times required to assess experimental

parameters, it is possible to learn much about a particular experiment and

possibly its behavior as an experiment aboard the space shuttle or space

station, without leaving the ground. A unique facility of this type

requires a large amount of resources available to perform the experiments,

maintain the equipment and to provide useful information in order to design

a good experiment.

The objective of this study was to develop criteria, using fundamental thermochemical dynamics, to assist a scientist using the Drop Tube

Facility in designing a good experiment. The types of parameters involved

in designing the experiments include the type of furnace, the type of

atmosphere, and in general which materials are better behaved than others

as determined by past experience in the facility. One of the major advantages of the facility lies in its ability to provide large undercoolings in

the cooling curve during the drops. The ability to predict such undercoolings has not progressed due to the lack of information with most

systems and lack of a suitable theory to predict such behavior.

Consequently, we felt that a good beginning was to consider the effect of

oxygen and other gases upon the amount of undercooling observed. The

starting point of the thermochemistry was given by Ellingham^ and later

transformed into what is known as the Richardson Chart (Figure 1).2>5

Having the local capability to calculate such quantities presented an early
objective. In addition data was to be obtained from experimental drops of

elemental species, in order to observe the effect of surface oxidations

upon the nucleation phenomena observed in each specimen.

II. Results

The thermochemical calculations for the free energies of formation

have been programmed on two different computers available to drop tube personnel. The first version was programmed using the IBM personal computer

and a later version was programmed on the Hewlett-Packard 9836 in the Drop

Tube Facility on the 15th floor. This report contains the IBM version of

the program, as well as several of the outputs, as Figure 3-6 and Appendix

A. The thermodynamics used for the calculation is given in Figure 2. Data

is taken from References 3 and 4. A major advantage of using local calculation capability over just extrapolating from Figure 1, is that as newer

data becomes available in terms of materials and phase transitions, the

drop tube user will be able to determine the thermochemistry more

appropriately for his circumstance. Also it is envisioned that the gas

effects will be extended to handle many more species in the future.

Figures 3-6 show program flow, data presentation screens for NiO and NiO

plot from IBM-PC.

The drops performed for this study are included in Tables I-III.

In addition, information is given in terms of the mass, the observations

performed and the resulting grain or dendrite measurements. As indicated

later, we were not able to correlate the surface oxide formation with

amount of undercooling, but we did establish that a new parameter needed to

be considered for a better understanding of the resulting microstructures.
Gas solubility, not considered previously as important as oxide formation

does show in our microstructure analysis that the morphology was affected

more by varying ambient atmosphere than by surface oxidation effects. We

still have not finished analyzing the specimens obtained during these

drops, but Tables I-III summarize the data obtained thus far fairly completely.

A major undertaking of this effort has been the microstructural

analysis performed by Dr. William Kaukler who has been extremely active in

similar work with low gravity experimentation from drop tower and KC-135

studies. Dr. Kaukler has been assisted by Ms. Donna Warden, an undergraduate student at UAH in performing most of the grinding, polishing and

photomicroscopy for the same studies. As seen in Table I, we have used

specimens of copper, rhodium, platinum, and nickel. The only reason for

using these elements were due to their availability and as far as we knew

at the beginning of this work, they were not being worked by other research

groups in cooperation with NASA.

III. Discussion of the Results

This discussion is presented to provide information about the type

of information obtained from these sets of experiments. The breakdown can

be classified according to the following areas:

Specimen Preparation for Metallography

Photomicrography of Specimens

Residual Gas Analysis

Analysis of Dissolved Gases

Summary of Etching Procedures
The complete interpretation and analysis will take some time to finalize.

We hope that this preliminary information will be of use to other scientists who are interested in using the Drop Tube in studies of solidification phenomena.

IV. Drop Tube Specimen Preparation for Metallography

Over 60 drop tube specimens were mounted, sectioned by grinding,

polished and analyzed metallographically. Tables 1-3 list the drop specimen parameters. Some specimens revealed microstructural details on their

exterior surfaces. These specimens were examined by scanning electron and

optical metallography prior to mounting and sectioning. Practically all

the experimental results are derived from these metallographic studies.

Microstructural correlations to the drop conditions are the prime observations. Photomicrograph of several interesting specimens are given in

Figures 8-10.

Specimens were as small as 20 milligrams in weight for the electron

beam experiments and 200-400 milligrams for the electromagnetic levitation

experiments. Such small samples represented considerable difficulty in

handling and in the proper performance of metallographic sectioning. All

specimens were near perfect spheres and the considerable surface curvature

made microscopic examination of exterior features nearly impossible.

Surface features were of considerable interest to this study because normal

shrinkage of the melt upon crystallization can reveal dendritic morphology,

which may yield details of its thermal history. No correlation would or

could be made between the site of apparent nucleation on sectioning and the

surface morphology. Dendrite arm spacing, if found on the surface could be

compared to the spacing, if seen, in the interior region of the specimen.
Most of the time consumed for this study was spent on the systematic development of the various metallographic techniques required to produce acceptable micrographs of the diverse specimen types. Many of the

specimens were soft metals which were further softened by their high purity.

Soft specimens scratch very easily, are deformed, are susceptible to surface deformation during mechanical polishing, provide little resistance to

machining, retain grinding and polishing abrasives by embedding into the

surface and cause other minor problems during metallographic analysis. In

order to minimize these difficulties, the specimens were individually

mounted and had embedded with them in the mount, a ring of glass around the

specimen. This ring stabilizes the orientation of the specimen, greatly

improves the characteristics of the polished specimen, and permits a less

skilled metallographer to achieve superior results.

Each different metal that was studied required its own procedure

for preparation. Mounting, grinding, and in general most polishing tasks

were done the same way, but skill was required in order to develop and

repeat the proper application of these steps. A variety of specimen

etching techniques had to be attempted despite the ready availabiity of

previously tested formulas and methods collected in reference texts. The

specimens selected for this study were prepared from the most pure elements

available. This leads to the most complicated feature of the

metallographic studies. When a metal is very pure, morphological features

formed during crystallization will not leave clear traces of their passing;

whereas common alloys always leave a clear trace of their passing. These

features can become indetectable to any method. Nearly always does grain

recrystallization occur unimpeded by the pinning effects on grain boun-
daries of solute atoms. Prior structure usually could not be revealed,

although dendrite arm spacing measurements on occasion could be made. The

heat of recalescence and the slow cooling rates after crystallization

together with the high purity enhance the rate of grain growth. At the

very least, grain structures could be revealed by some etching techniques.

Again the high purity and nobility of some of the elements studied required

concentrated effort to find acceptable etchants. If chemical etchants were

not successful, some success was obtained with electrolytic etching

methods. A facility for electro-etching of metal specimens was established

as a result of this requirement (See Figure 11). The high nobility of some

of the metals required aggressive techniques for etching. Therefore, the

only microstructures revealed were the grain boundaries. Summarized in

this report are also the best etchants and additional cautions for such

elements studied.

All the specimens had to be mounted in plastic "cold mount" prior

to grinding. The best material was found to be a product from SPI, a polymethyl methacrylic material. Specimen mounts were standard metallurgical

types, approximately 30 mm. in diameter.

Grinding was performed wet with tap water as the lubricant.

Wet/dry grinding papers with corundum grit were used with the standard

sequence of 120, 180, 230, 420, and 600 grit for all specimens.

Mechanical polishing was performed at first with alumina polishing

suspensions in water having particle sizes of 5, 1, 0.3 micrometers.

Coarse and then fine polishing was always performed with billiard cloth for

the fine polish and "Super Finale" cloth for coarse. For the latter half
of the study, a more expensive and troublesome diamond polish was performed. Surface finish was superior and polishes were done more quickly,

but scratches were always found and highly revealed by the etching process.,

Both coarse and fine diamond polishing was performed with 1 and 0.25 micrometer diamond particles used in a suspension of diamond polishing oil. The

best cloth was found to be "Rayvel" from Beuhler for both grit sizes.

Copper was prepared by the first mechanical polishing followed by

a chemical polish prior to the chemical etch. The chemical polish removed

the scratches of the mechanical polish and produced a superior surface.

The formula is included together with the etchants.

V. Photomicrography of Specimens

Metallographic examination of the drop tube specimens combined

exterior observation by optical and electron microscopy with micrography of

the polished and etched sections. The features which were examined for

included dendrite size and spacing, surface oxidation, grain size, porosity, and sites of nucleation if found. The dimensions of these features

are such that only low magnifications are required. Given the dimensional

range, more stereological measurements per micrograph can be made for the

lower magnifications, thus providing improved statistics.

A Zeiss Ultraphot Research Microscope and Unitron U-ll

Metallograph were used for optical metallography. A Jeol UM-3 Scanning

Electron Microscope was alsc used for surface examination. Nearly all the

metallography centered around the micrography of polished and etched sections of the drop tube specimens. When photographs were taken with the

Zeiss microscope, either Polaroid type 58 film (color) or type 57 film
(black and white) was used, and with the Unitron, Polaroid type 108 or 107

film was used. Kohler, bright field illumination was used in most cases.

Occasionally, when polished but unetched specimens were studied, Nomarski

interference contrast illumination was used to reveal the subtle variations

in surface texture. Surface examination and optical photomicrography were

done using dark field illumination on the Zeiss microscope. This type of

lighting enhances the contrast for the very rough structures, sometimes

seen due to solidification shrinkage in interdendritic cavities.

All the special lighting techniques are available on the Zeiss

microscope. Three objective lenses yield three different magnifications;

40X, 65X, and 260X. Only Kohler illumination was available with the

Unitron U-ll and all micrograph were taken with the 10X objective,

resulting in a 136.5X magnification in the photomicrograph.

Except when Nomarski illumination was used (which creates a

pseudo-color image), the specimens showed no color. As a result black and

white micrographs were taken of these specimens. The exception is the

copper specimens which, when etched, revealed various shades of orange and

brown. Some color micrographs were taken of these.

VI. Residual Gas Analysis

Knowledge of the quality of the atmosphere in the drop tube

environment is critical for studies of this nature. The partial pressures

of the significant gaseous species; oxygen, hydrogen, water, carbon

monoxide, helium and carbon dioxide collectively can control the chemical

potential for reaction at the elevated temperatures used with these types

of materials. Either oxidation or reduction of the metal could be per-
formed during its fall through the ambient atmosphere within the tube by

suitable gas selection. Even a high vacuum (less than 10-6 atmospheres)

can contain enough oxygen or water vapor to cause some reactive metals to

oxidize significantly. Quantification of the amount of these gases can

most easily be performed with a residual gas analyzer or mass spectrometer.

In our study, a UTI 100C quadrupole was borrowed from another group and

used in the earlier phases of the study, but it was an older system and had

many problems in providing data when required. Consequently the Drop Tube

Facility purchased a Dycor Electronics M/100M series quadrupole mass

spectrometer for dedicated use at the facility. This unit was installed at

the top of the tube, in the bell jar region above the isolation valve. This

unit has a mass range of 1 to 100 amu and utilizes an electron multiplier,

thus allowing us to make sensitive partial pressure measures of gases and

vapors. Other features of this particular model includes programmed computer control, large CRT display, and printer output of display information. Various display formats are available, including analog, bar

representation, tabular, etc.; enabling the data to be displayed a number

of different ways.

VII. Performing Residual Gas Analysis on the Drop Tube

The Dycor quadrupole mass spectrometer has been installed into the

bell jar region using a scheme which allows the bell jar region to be monitored at both low and high pressure regimes. Two different valves for

controlling the sampling parameters of the tube are used in this scheme. A

variable leak valve, which allows sampling at very high pressures, is

available for pressures above 10-4 atmospheres and for pressures below that

value a manually operated gate valve is available. Using these two valves
the quadrupole is capable of operating over a very large dynamic range.

Under the conditions of our measurements, we used the same turbomolecular

pump that pumps on the belljar region to pump out the quadrupole region. A

major disadvantage of this approach is that the maximum sensitivity of the

instrument is not achieved because the sensing environment is not at a

lower pressure than the environment being sensed. We have since then

installed a Cryogenic pumping system in order to attain pressure values for

the quadrupole region to be much less than for the belljar region. In particular it is important to clean up the water vapor if we are to measure it

correctly.

For our measurements, we used a value of 125 for the setting on

the variable leak valve and systematically stayed with that leak rate. No

actual measurement of the leak rate was made since we did not have the

cryogenic pump installed and such a measurement would have been difficult.

Working with ratios of known gaseous components is sufficient in most

cases. In operation, the use of the variable leak valve allowed a

controlled leak from the belljar region into the quadrupole region to

occur. The continuous stream of gas passed through the ionizer region of

the mass spectrometer chamber being pumped upon by the turbomolecular pump.

In this way we were able to obtain scans of the belljar atmosphere under

prescribed conditions. An example of such a scan is given in Figure 11. A

noticeable feature of the scans obtained with this system is that the peak

heights are influenced by two parameters not built into the software

controlling the display information. One parameter is the efficiency of

ionization (and associated cracking pattern) and the other is mass discrimination effects of both the variable leak valve and the mass spectrometer

10
itself. This type of variable leak valve uses the volume between two

cylindrical surfaces to determine the leak rate and provides a difference

in leak rate by varying the overlap region of the two cylinders.

Unfortunately this technique does give some mass discrimination and small

molecules such as helium and hydrogen do leak at a proportionately higher

rate than larger molecules. This can be calibrated and to some extent compensated for, as can other types of mass discrimination once their causes

are identified.

VIII. Dissolved Gases

As indicated earlier the major objective of this project was to

determine the effect surface oxides would have upon heterogeneous

nucleation in undercooled pure metal droplets. This study has indicated

that the proper approach is to also account for the effect of gas solubilities, in addition to the chemical reactivity of the various gases present

in the atmosphere of the drop tube. Redox reactions and the oxides that

result are not the only gas related effects upon the microstructure. Free

energies of formation of these oxides and their sensitivity to temperature

and pressure were discussed earlier in this report. During the examination

of the specimen sections fine dispersions of porosity were found within

many of the specimens. The morphology of these pores indicate that they

formed as a result of the nucleation of dissolved gas throughout the melt

upon cooling. Many specimens show the formation of these pores occurred in

the liquid that was last to solidify in the interdentritic regions. The

porosity often outlined the interdendritic regions and thus verifies that

they resulted from the segregation or partitioning effect of the advancing

solidification front.

11
The cleanliness of these pores prevents a direct assessment of the

gas species which caused their formation, hence we felt that a survey of

the data for gas solubility was the next best approach order to select the

best candidate. One must also recognize that the formation of oxide does

not indicate lack of solubility of the oxygen in the melt since solubility

measurements do not always preclude a reactive mechanism at work. For

porosity to form most readily the solubility fo the gas in the solid should

be significantly lower than in the melt. In addition, adequate partial

pressure of the gas would be required to cause the solution of the gas. In

the experiments presented here, the small droplet sizes with their high

surface to volume ratios and the high temperatures within the furnace

region would ensure rapid solution.

Three elemental gases can be considered that could cause the porosity observed. They are hydrogen, oxygen and nitrogen. Both oxygen and

hydrogen also may go into solution from dissociated water vapor that is

always in the drop tube atmosphere. The noble gases helium and argon do

not dissolve in any metal to a measurable degree. Sievert's Law applies

with hydrogen at least

Sa = k/Pa" ;

solubility being proportional to the partial pressure of the gas.

A summary of data discussed in reference gives us the following

information.

Nitrogen is insoluble in the following metals up to 1400 C. for

the following three metals:

Copper

Nickel

Palladium.

12
Hydrogen is soluble in the following metals:

Copper - .03 atomic percent at melting point for liquid

.009 atomic percent at melting point for solid

Nickel - 0.1 atomic percent at 1453 C solid

0.2 atomic percent at 1453 C liquid

Platinum - low solubility

0.0164 atomic percent at 1342 C. Tm = 1769 C

Palladium- 0.7 atomic percent at 1552 C, solid

0.4 atomic percent for liquid

high solubility, but decreases as T goes up

Rhodium - little solubility, very low

Oxygen:

Palladium- PdO decomposes at 750 C

solubility is 0.63 atomic percent at 1200 C.

Platinum - no data found

Rhodium - dissolves a considerable amount at high temperatures. Rh203 decomposes at 1100 C in 1

atmosphere of oxygen

Copper - Copper and oxygen form a eutectic with low solid

solubility of oxygen in copper where there was

less than 0.036 atomic percent at 1000 C. the

eutectic temperature is 1065 C and the eutectic

(with cuprous oxide) composition is 1.5 atomic

percent. There is unlimited solubility of oxygen

in copper or nickel some 20 C above the eutectic

temperatures.

Nickel - Nickel and oxygen form a eutectic with increasing

solubility with decreasing temperature where we

have 0.044 atomic percent oxygen in the solid at

1200 C. The eutectic temperature is 1438 C, and

the eutectic point is 0.87 atomic percent oxygen.

In summary then nitrogen cannot cause the observed porosity in all

cases because of the variety of ambient atmospheres used. Also since the

helium-hydrogen mixture contained no more than 5% hydrogen, and the overall

pressure used was normally around 200 - 300 Torr, then the partial pressure

of the hydrogen would be only around 0.1 to 0.2 Torr. A high solubility of

13
0.7 atomic percent of hydrogen in Palladium at 1 atmosphere would then give

only 0.0001 atomic percent. Alternately, the solubility of hydrogen in

copper liquid would only be 0.000005 atomic percent for the low partial

pressure of hydrogen in the tube. So it is unlikely that raw hydrogen was

solubilized by the melt. The low partial pressure of hydrogen was confirmed as well by the mass spectrometer measurements.

Since porosity was observed predominantly in the nickel samples

processed in air and helium-hydrogen mixture and in the palladium samples

process in air, it is a fair conclusion that the dissolved gas was oxygen,

either from the atmosphere or from the oxide.

IX. Summary of Etching Procedures

1. Chemical Polish for Copper:

After mechanical polish at 5 micron alumina or diamond grit,

submerge specimen in solution for several seconds at a time until

surface scratches have been removed. Use at room temperature or

warmer.

Nitric Acid 30 ml

Hydrochloric Acid 10 ml

Phosphoric Acid 10 ml

Glacial Acetic Acid 50 ml

Taken from reference

2. Chemical Etchant for Copper:

Immediately after chemical polishing with procedure given

above, followed by rinsing; a brief few seconds in this etchant

14
will reveal grain and dendrite structures. The etchant is a

dilute (10%) solution of a commercially available etchant for

printed circuit boards, which primarily contains ferric chloride

solution.

3. Chemical Etchant for Nickel

Use freshly prepared for 5 to 30 seconds, thereby revealing

grain boundaries in high nickel alloys. Use after mechanical

polishing.

Nitric Acid 50%

Glacial Acetic Acid 50%

Taken from reference

4. Chemical Etchant for Palladium

This etchant is a dilute solution of a commercially available

chromic acid/sulfuric acid solution used as a glassware cleaning

acid. A 5 to 10% dilution of the glass cleaner solution was found

to work for palladium, where no other techniques worked. The

treatment needed 30 to 60 seconds in order to work at room temperature or warmer.

5. Electro-etchant for Platinum, Rhodium, and Iridium

The following solution was fund to be the best to reveal

grain boundary structure in the above elements. A graphite

cathode was used with 6 volts AC to the sample and electrode. The

solution was used at room temperature and constantly stirred to

15
remove the adherent bubbles formed during the reaction. Often as

many as 2 minutes of treatment was required for rhodium and as

little as 20 seconds for platinum. Etching was performed after

the mechanical polishing and etching.

Taken from reference 6.

6. Specimen Cleaning - General procedure

In all cases the general procedure was to rinse the specimen

with water, then with alcohol and dried with clean pressurized air

between each treatment. Often considerable drying and rinsing was

required to prevent acid trapped in pores in the specimen from

attacking the surface when it subsequently exits from the specimen.

16
BIBLIOGRAPHY

1. Ellingham, H.T.T., Jour. Soc. Chem. Ind. (London) 63, 125 (1944).

2. Swalin, Richard A., Thermodynamics of Solids; Wiley & Sons, New York

(1972).

3. Barin, I., 0. Knacke, and 0. Kubaschewski, Thermochemical Properties

of Inorganic SubstancesU; Springer-Verlag. Berlin (1973).

4. Barin, I., 0. Knacke, and 0. Kubaschewski, Thermochemical Properties

of Inorganic Substances Supplement; Springer-Verlag, Berlin (1977).

5. Lupis, C.H.P., Chemical Thermodynamics of Materials; North-Holland,

New York (1983).

6. Petzoe, G., "Metallographic Etching", American Society for Metals,

Metals Park (1978).

7. Smithells, C.J., "Gases and Metals", London, 1937.

17
TABLE I

Summary of Drop Tube Specimens

Legend:

IDf

NT221

NT224

NT227

NT228

NT 269

NT 339

NT 344

NT 346

NT 349

NT 351

NT357

NT417

NT420

NT422

NT426

NT427-8

NT434

NT435

NT446

NT447

NT448

NT449

NT450

NT451

pee:

pe:

pr:

sem:

C:

picture, electro-etched

picture, chemically etched

picture, real surface (light

scanning electron mi

cooling curve

Material Initial

Weight

Rh

Rh

Rh

Rh

Rh

Cu

Cu

Pd

Cu

Cu

Cu

Pd

Pd

Pd

Ni

Ni

Cu

Cu

Ni

Ni

Ni

Ni

Pd

Pd

316.99

338.63

190.83

252.43

250.0

229.48

300.15

213.43

249.28

335.36

351.61

croscope

Final

Weight

316.43

321.25

252.81

248.03

300.0

300.16

213.57

294.47

334.12

334.12

microscopy)

Comments

High purity, e-beam, pee

High purity, e-beam,

mounted not etched

High purity, e-beam,

mounted not etched

High purity, e-beam,

mounted not etched

High purity, pee

Electrical wire, not

mounted

High purity, HE+H atmos,

dropped into Al foil, pe

Arced and splattered, not

mounted

High purity, He+H atmos,

C

High purity, He+H in

tube; C. Ar in bell jar,

dirty, pe

Air in bell jar, C, He+H

in tube, air in catch

tube

pe

pe

splattered

He atmos, pr, pe, sem

He atmos, pe

He+H atmos, not totally

melted, pe

He+H atmos, not totally

melted, pe

He+H, pe, C

He+H atmos, pe, C

He+H atmos, rainy day,

sem, pe

He+H atmos, rainy day,

sem, pe

He+H atmos, rainy day,

pe, sem

He+H atmos, rainy day,

splatted
TABL

E I. (cont.)

ID#

NT452

NT453

NT454

NT455-6

NT457

NT458

NT459

NT460

NT461

NT 462

NT463

NT464

NT465

NT468 '

NT 469

NT470

NT472

NT474

NT 559

NT 560

NT577

NT578

NT581

NT582

NT583

NT584

NT585

NT 586

NT587

NT589

NT 590

Material

Pd

Ni

Ni

Ni

Cu

Cu

Pd

Pd

Pd

Pd

Cu

Cu

Cu

Pd

Pd

Pd

Cu

Cu

Ni

Ni

Cu

Cu

Cu

Cu

Cu

Cu

Cu

Cu

Cu

Ni

Ni

Initial

Weight

371.32

358.74

350.0

295.9

360.5

372.88

387.77

393.32

311.23

323.39

374.03

285.24

240.14

232.25

244.30

189 . 10

184.89

268.30

177.89

371.30

380.74

Final

Weight

360.0

342.94

238.78

230.8

240.31

185.98

183.07

231.77

233.77

176.14

371.00

380.74

Comments

He+H atmos, pe

.Air, pe, C

Air, pe, C

No melt in air

Air splat, C

Air splat, C

Air, pe

Air, pe, C

Air, pr, pe, sem

Air, pe

Air splat, C

Air splat, C

Vacuum splat, C

Vacuum splat, C

He+H atmos, pe

He+H atmos, pe

He+H atmos, pe

High purity,

He+H atmos, pe

Vacuum, pe, C

Vacuum, sem, pe,

C

He+H atmos, in-

complete melt,

not mounted

He+H atmos, fell

from coil , not

mounted

He+H atmos, not

mounted

He+H atmos

He+H atmos, not

mounted

He+H atmos, not

high purity, not

mounted

He+H atmos, half

splat, data as

NT 584

He+H atmos,

elongated half

splat, test

He+H atmos,

incomplete melt,

not mounted

He+H atmos

He+H atmos
TABL

E I. (cont.)

IDf

NT 591

NT 59 2

NT594

NT624

NT625

NT627

NT630

NT657

NT659

NT 661

NT662

NT663

NT664

NT665

NT670

NT671

Material Initial

Weight

Pd 269.02

Pd 196.76

Cu 163.73

Pt

RhPtPtPtPtPtRhPtRhRhIrIr

Final

Weight

258.51

189 . 19

162.54

65.4

50.23

24.28

20.61

59.3

23.2

30.7

76.81

33.92

Comments

He+H atmos, pe

He+H atmos, pe

He+H atmos, not

levitated, not

mounted

E-beam, vacuum,

pee, C

E-beam, no data,

pee

E-beam,

incomplete melt,

not mounted, C

E-beam, pee

E-beam, no data

E-beam, wire

sample, C

E-beam, no data,

not mounted

E-beam, irregu-

lar shape, may

have wire in it,

C

E-beam, wire

imbedded in it,

C

E-beam, wire

imbedded in it,

C

E-beam, may have

wire imbedded in

it

E-beam, wire

imbedded in it

E-beam, may have

wire imbedded in

it
TABLE II.

Summary of Drop Tube Specimen Grain Size

Sample

Number

NT221

NT 269

NT 344

NT 351

NT448

NT449

NT452

NT453

NT454

NT460

NT461

NT462

NT470

NT474

NT560

NT582

NT585

NT586

NT 589

NT590

NT 591

NT 59 2

NT625

NT630

Element

Rh

Pd

Cu

Cu

Ni

Ni

Pd

Ni

Ni

Pd

Pd

Pd

Pd

Cu

Ni

Cu

Cu

Cu

Ni

Ni

Pd

Pd

Rh

Pt

Atmosphere

E-beam

E-beam

He+H

He+H

He+H

He+H

He+H

Air

Air

Air

Air

Air

He+H

He+H

Vacuum

He+H

He+H

He+H

He+H

He+H

He+H

He+H

E-beam

E-beam

Grain

Size (cm)

.0171

.0131

.0969

.0252

.0252

.0297

.0184

.0163

.0304

.0056

.0056

.0059

.0221

.0236

.0143

.0249

.0074

.0246

.0192

.0223

.0151

.0111

.0044

.0085

Standard

Dev. (cm)

.0076

.0035

.0031

.0175

.0103

.0102

.0093

.0048

.0105

.0022

.0022

.0019

.0078

.0084

.0071

.0118

.0037

.0136

.0088

.0119

.0057

.0061

.0024

.0021
TABLE III.

Sunwary of Dendrite size Measurements

Sample

Number

NT417

NT420

NT427-8

NT460

NT461

NT462

NT474

NT582

NT624

NT625

Element

Pd

Pd

Ni

Pd

Pd

Cu

Cu

Cu

Pt

Rh

Dendrite

Size (cm)

0.0066

0.0086

0.0030

0.0056

0.0056

0.0059

0.0111

0.0070

0.0011

0.0024

Standard

Deviation

0.0023

0.0021

0.0008

0.0022

0.0022

0.0019

0.0042

0.0014

0.0004

0.0006
OF POOR QUALJTY

-

Ol

 «-« OC-01 .-"'

 V KOCtI OKI 0001 008

juiod

uoi)BLUi|qns

juiod 3ui|iog

luiod

?

je "a'i *

umiejuos *oeaJ oi si uoijisoduiooap

-spunodujos aujaiuoiipiois 01

saiidde pue leonamodXy si aui|

III! !

9OI/t tOt/I jOI/I <X1UO!H/£H

Figure 1. Richardson (or Ellingham) Diagram
Figure 2. Thermochemical calculations for Richardson charts

High

Temperature T

• 298°K

AG

metal(H,S.) + 0 2 (N,S) metal oxide(H,S)

/

AH

AS

> '

AH

AS

/

AH

AS

/

metal + Oc

metal oxide

H(T) = AH where

T

 n

cp dT + ^ H.

S(T) = AS°gQ + AS

where

/• T n

AS = [ cp/T dt + £ Hi / T

-^298 1 = 1

AH(T) = H(metal oxide) - H(metal) - H(02 )

AS(T) = S(metal oxide) - S(metal) - S(02)

AG(T) = AH - T AS = RT log Po2
1 ENTER DATA FOR REACTION

WLECULAR RATIOS

STANDARD ENTHALPY

STANDARD ENTROPY

HEAT CAPACITY COEFF.

FREE ENERGY CALCULATIONS

MENU

ENTER CHOICE?

7 EXIT PROGRAM

SAVE DATA TO DISC

ENTER NAME OF DATA FILE

ENTER DISC DRIVE A OR B

ENTER NAME OF REACTION

PRODUCT

3 READ DATA FROM DISC

ENTER NAME OF DATA FILE

ENTER DISC DRIVE A OR B

ENTER NAME OF REACTION

PRODUCT

6 PLOT GRAPH

ENTER MAX. TEMPERATURE

DISPLAY PHYSICAL CONSTANT CALCULATE FREE ENERGIES

DELTA H

DELTA S

H TOTAL

S TOTAL

DELTA G

REACTION

TEMPERATURE RANGE

ENTHALPIES

ENTROPIES

HEAT CAPACITY COEFF.

Figure 3. Menu driven program flow nodes

for easy user interface
2 HI t 02 —) 2

GE 1 IS 25 10 252 DEGREES C

-57588

9,188881

HEAT CftPflCIlY COEFFICIENTS

7,8 7,82

-.43 8 37,58

C -1.335 8 3,

C

EH1ER <CR> 10 GET HEH lift OR <)(> i <CS) TO GO 10

Figure 4. Thermochemical constants for first temperature range

o
REACTION 2 HI t 02 —> I

lEHPERfliyRE RANGE I IS 253 TO 292 DEGREES C

7,14 49 9

HEfll CAPACIH COEFFICIENT

7,1 7,

i

C -2,23

AT 292 DEGREES C PHASE TRANSITION VALUES ARE

EH1ER <CR> TO GET Ml DAIA OH <X> § <CR) TO GO

Figure 5. Thermochemical constants for second temperature range
REftClIOH 2 NI * 02 —} 2 NIO

lEHPERftTORE RftNGE 3 IS 293 10 1984 DEGREES C

ENIHflLPY 8 8

7,14 49

HEftI CftPftCIM COEFFICIENTS

ft 9,3 7,82 11,18

B 8 8 2,82

C

0 2*• 393

"O S O £p

o s>

•O r°

O "$

> «

3•< t-»

m 10 GET NEXT Bfilft OR <X> 8 <CR> 10 GO 10 MEMO?

Figure 6. Thermochemical .constants for third temperature range
£«

I

/ I

<1

JL.

2599

1500-

g

•o

500

kcal -150 -250 -300

Figure 7. Ellingham chart for N^O from IBM

PC screen dump with overlaid 102 scale
Pd, NT591

65X

Pd, NT592

65X

Figure 8. Photomicrographs of two Palladium

drops. Data is given in Table 1

ORIGINAL PAGE 13

OF POOR QUALITY
V •'••"'• iJ«». i '."•

y-i •.. p1?*-~ ••/• '.J.

f^. ,TA. ' / ••/'• w r~< /-^ o^vriF- *

v'*f^v.' ;> c^^\ •v ' ^r%^p\^-'

i'^rf'^.^^

* "K'-*1 ; -"' Ti- zc^J

I -- ^^>% \ « - *^^» V*% >&****• ^.V"^^

Ni, NT590

65X

Figure 9.

Ni, NT448

65X

Photomicrograph of two different Nickel drop

specimens. Data is given in Table I.
ORIGINAL PAGE 13

OF POOR QUALITY

^ymm^W^ tr-*L^£&s^Kyz%fni/:.

Vstu -*"*^f'/»/r'*.».-/.. / •

.~~Z. ~.*f/*('*?.-

 <*-/

.-*^U

Cu, NT585

65X

Figure 10

Photomicrogrpahs of

two unique specimens,

copper and nickel

Data is summarized

in Table I

Ni, NT427-8

40X
O!

I±

VOLT METER

-SAMPLE

GRAPHITE

XlELECTRDDE

r^-STIR BAR

STEP-DOWN

TRANSFORMER

O O

STIRRING

HOT PLATE nbv

AC

VARIAC

-- STIFr VIRE --_

, ETCHANT LEVEL

\

'HOLE FCR VIRE

ntn

I II

Specimen mount partly

I submerged in etchant

to allow metal specimen i

to make electrical 1

contact.

FRONT VIEW SIDE VIEV

Figire 11. Electro-etching apparatus

constructed for this work
101ALPRS 9,9E-06|DISP SPEC) 6-A (SCAN SPEC B | 10/8/8516:14

1.0E-05

E-06"

E-07'

L O U

Hil l

NO,

1

Ifl

I)

S

MIMMI I 1 M M M M

10 26

SS 1, DUE

SS 50, SCfl

CANS -1, AU1

M IIIMMIMIII M 1

30 40

:LL is USE

LE 3 DEC LC

'02ERO ON

M 1 1 1 1 1 M M M 1 1 M 1 M 1 1 1 [1 1 1

50 M 70

1C EMISSION 1.0E-03

iG EL ENERGY -70,0

FOCUS -20,0

ELEC HULI OFF

I I II I I I M I I I I 1 M 1 I I I I I I 1 1

FIL ON

FIL HOLTS 2,4

FIL CUR 3,0

FIL RES 0,79

Figure 12. Mass spectrum using Dycor system and

subtraction of background feature.
APPENDIX A
AFREE ENERGY PROGRAM

written in Microsoft BASICA

for the IBM Personal Computer

Comments: This program has been written with a menu driven user

inter-face far ease of use. Each task such as enter data, read data

from the disk, calculate free energies to a specified temperature, or

to plot data is determined through a primary menu.

9 REM SET-UP AND PRIMARY MENU

10 DIM C*(3),M(3),H(3),S(3),A(3,9,4),HP(3,5),SP(3,5)

20 DIM TP(20)

30 KEY OFF

100 CLS

PRINT

TAB<20);"FREE ENERGY CALCULATIONS MENU"

j lu

120

130

140

150

] 6'J

170

JSO

] 90

20< >

210

?2<">

23O

24 O

25O

PRINT

PRINT

PRINT

PRINT

PRINT

PR f NT

PRTNT

PRINT

PRINT

PRINT

PRINT

PRINT:PRINT

PRINT:PRINT

PRINT:PRINT

PRINT:PRINT

PRINT:INPUT

ON C

GOTO

STOP

TAB(5)

TAB(5)

TAB(5)

TAB(5)

TAB(5)

TAB(5)

TAB(5)

TAB'S)

1

"4

"5

"6

"7

"8

ENTER DATA FOR A REACTION"

SAVE DATA TO DISK."

READ DATA FROM DISK"

DISPLAY PHYSICAL CONSTANTS"

CALCULATE FREE ENERGIES"

PLOT ONE REACTION"

PLOT SEVERAL REACTIONS"

EXIT PROGRAM"

"ENTER CHOICE"; C

GOSUB 300,600,900,1100,1300,

100

500,3500, 30

29i:l

REM

300

5 J 0

315

32>O

T?5

"V^O

335

340

•-.5"

360

rv/o

375

380

384

390

395

430

440

450

460

4 70

REM THE DATA

THE RE

CLS

1 NPU f

] NPUT

INPUT

INPUT

I NPUT

INPUT

FOR I

CLS

PRINT

INPUT

INPUT

INPUT

FOR J

INPUT

PRINT

PRINT

PRINT

INPUT

INPUT

INPUT

IFERENC

"enter

"enter

"ent-er

"enter

"enter

"enter

-- 1. TO

"eni-.er

" enter

"enter

"enter

= 1 TO

"enter

"enter

"enter

" enter

"enter

ENTRY SUBROUTINE WITH DATA ENTERED FROM TABLES IN 299

: TABLES OF BARIN., ET AL.

metallic- reactant " ; C$ (1)

molecular ratio ";M(1)

gaseous reactant ";C*<2>

molecular ratio ";M(2)

r-eaction product ";C$(3)

molecular ratio ":M(3)

data for "; C$(I)

standard enthalpy at 25 degrees C

standard entropy at 25 degrees C '

number of phases";N(I)

N (I)

upper temperature ";T2(I,J)

heat capacity

A roef f 3 cuent'

B coefficient

C coef f j ci >-'nt'

coefficients A,B,C,D for i C*(I)
480 INPUT "enter D coefficient";D

490 Ad, J, 1)=A:A(I, J,2)=B:Ad, J,3)=C: A<I , J,4>=D

495 PRINT

500 INPUT "enter 'N' if no phase change occurs at upper

temperature";N*

51U IF N* = "N" THEN 540

520 INPUT "enter enthalpy change at phase change temperature ";HP(I,J)

530 INPUT "enter entropy change at phase transition ";SPd,J>

540 NEXT J

550 NEXT I

560 RETURN

600 CLS

A10 F*= "DATA": INPUT "ENTER NAME OF DATA FILE "; F*

620 INPUT "ENTER DISI- DRIVE A OR B";D*

630 FILE* = D*+":"+•!-*+".DAT"

640 OPEN FILE* FOR APPEND AS ttl

660 FOR 1=1 TO 3

670 WRITE #1,C*(I) ,M(I) ,N(I),K(I) ,S (I)

680 FOR J = 1 TO N(T)

690 WRITE ttl,T2d, J> , Ad, J, 1) , Ad, J,2> , Ad, J,3) ,Ad, J,4>

700 WR I TE tt 1, HP (I', J ) , SP (I, J )

710 NEXT J

720 NEXT I

730 CLOSE 1

740 RFTURN

099 REM RETRIEVE DATA FROM DISK

900 CLS

910 r*~ "DATA":PRINT "ENTER NAME OF DATA FILE ";:INPUT F*

930 FILE* - F*+".DAT"

940 INPUT "ENTER NAME OF REACTION PRODUCT " ; R*

950 OPEN FILE* FOR INPUT AS ttl

960 IF EOFCl) THEN 106O

98<) FOR I = 1 TO 3

990 J NPUT tt1,C*(I) ,M(]) ,Nd),H(I) ,S(I)

100'"i FOR J - 1 TO N d)

1.010 I'NPUT ttl,T2d, J) , Ad, J, 1) , Ad, J,2) , Ad, J,3) , Ad, J,4)

102') INPUT #1, HP (I, J) , SPd, J)

1030 NEXT J

1040 NEXT I

10t*0 IF C*(3) •. R* THEN 960

1060 CLOSE 1

IO7O G OS I IB 300O

JOB" RETURN

1«'V9 r<LZM THI'G ROUTINE PRINTS THE CHERMODYNAMIC VALUES

1100 FOR J = 1 TO PMAX

1110 CLE

1 11-'O PR INT " REACT I ON " „ M d ) ; C* d ) ; " + "3 C* (2) ; " - -.

";M(3);C*(3)

1125 PRINT:PRINT

U30 PRINT "ENTHALr/",M(I),H(2),H(3)

J135 PRINT

1140 PRINT "ENTROPY",Sd) ,S(2) ,S(3)
sPRINT

"TEMPERATURE

1 3 q-5 PRINT

1 if,0 PRINT

DEGREES C"

LI55 PRINT

1 3 oO PRINT

1170 PRINT

1180 PRINT

1190 PR]NT

1200 PRINT

1205 PRINT

1220 PRINT "EN

1230 PRINT "EN

1 ;'40 LOCATE 24,5

1250 INPUT "ENTER • CR

MENU";A*

1260 IF A* = CHR*(S8)

J270 NEXT J

1280 RETURN

RANGE: ",-j; TP(J>

:PRINT

"HEAT CAPACITY COEFFICIENTS"

"A", AX (1 , J, 1 ) , AX '2., J, 1) , AX (3

"B",

up ii

<-' j

"D",

3,J,

AX

AX

1ALI

•<OF

< J

(1

PY

Y"

, J

» J

ii

,

,

T

J -'

,4

HX

SX

> '

) ,

(1

(1

AX

AX

AX

q W

2 , J

1

 2, J

(2, J

) ,H-X

) ,SX

r

~

l

, k_) /

, 3)

,4)

(2,

(2,

q

1

J

J

AX

AX

AX

) ,

) ,

(3

(3

(3

HX

SX

i ^J

1 "

, J

(3

****. r«BE B

P00« QUUlv

TO

rP(J-M> ;

- TO GET NEXT DATA OR

THEN RETURN

1)

2)

.3)

4)

J)

, J)

=.:x:.- & <CR. TO GO

1299 REM THIS SUBROUTINE CALCULATE THE DELTA G VALUES

1300 CLS

1310 LPRINT "REACTION",M(l);C*(1);" + ";C*<2)" -->

";M(3);C*(3>

1320 LPRINT:LPRINT "TEMP","DELTA H","DELTA S","DELTA 6"

1340 TtA = Tl(1) + 273

1360 JNPUT "E'NTER MAXIMUM TEMPERATURE FOR THIS CALCULATION"; TMAX

1370 FOR T2A = TJA TO TMAX + 273 STEP 50

1380 GOSLIB 2000

1390 LPRINT T2A,HREACT,SREACr,6T2

1400 NEXT T2A

1480 PRINT "MOLAR ENTHALPIES ARE " ; HTOTAL (1) , HTOTAL (2) ., HTOTAL (3)

1490 PRINT "MOLAR ENTROPIES ARE "; STOTAL(1),STOTAL(2),STOTAL(3)

.1350 PRINT "THE FREE ENERGY AT "jTMAX?" DEGREES C IS

";GT2;"CAL/";M(3>;"MOLE

15AO PRINT

1580 INPUT "ENTER =.CR> TO RETURN TO MENU OR ^PrtScP TO PRINTER ";

1590 RETURN

1999 REM THIS SUBROUTINE

2000 FOR I = 1 TO 3

201.0 I-IS(I) •= H(I) sSS(I) =

2020 TiA = TP(,I) + 273

2030 HS(T) = HS(I) H- HX(I

2050 HCAPA(I) - AX(I,J, 1)

2060 HCAPB(I) = AX(I,J,2)

2070 HCAPC(I) = AX(I,J,3)

2080 HCAPD(I) = A X(I,J,4)

2090 HTOTAL (1) = HS ( I) •+

2100 EIMTRA<1) =

2110 ENTRB(I) =

2120 ENTRC(I) =

2130 ENTRD(I) =

2140 STOTAL(I)

2150 NEXT I

PERFORMS THE SUMMATION OVER THE COEFFICIENTS

, J- 1 ) : SS ( I ) = SS (I ) +• GX ( I , J-- 1 )

* (T2A-T1A)

* .5 * 10----3 * (T2A*T2A--T1A*T1A)

* 10--5 * (1/T1A - 1/T2A)

* .333 * 10---6 * (T2A*T2A*T2A - T1A*T1A*T1A)

HCAPA ( I ) H- HCAPB ( I ) + HCAPC ( I ) + HCAPD ( I )

* LOGCT2A/T1A)

10---3 * (T2A--T1A)

10---5 * <2#(TlA-'-2 - T2A--2))

.5 * 10' -6 * CT2A*T2A-T1A*T1A)

AX(I,J, 1)

AX a, J,2)

AX(I,J,3)

AX<I,J,4)

SS(I) + ENTRA<I)-+ ENTRB(I) + ENTRC ( I) + ENTRD (I)

*

*

*
2160 HREACT = M(3)#HTOTAL(3) -

217O SREACT = M(3)flSTOTAL(3) -

2180 6T2 = HREACT - T2A*SREACT

2190 RETURN

M(1)#HTOTAL<1)

M<1)*STOTAL(1)

HTOTAL<2)

STOTALC2)

2498

2499

2500

2510

2520

2530

2540

2550

2560

2570

2580

2590

2600

261O

2615

2620

2625

2630

2640

2650

2660

2670

2675

26(30

2690

270O

REM THIS SUBROUTINE PERFORMS THE GRAPHICAL TASKS FOR A SINGLE

REM REACTION

CLS

INPUT "ENTER MAXIMUM TEMPERATURE FOR THIS CALCULATION"; TMAX

GOSUB 4000

TSC = 180/3000

FESC = 600/300000'

T1A = TP(1) + 273

HGRD = M(3)#H(3) - M<1)*H(

SGRD = M<3)*5(3) - M (1) *E

GRFE •= HGRD - T1A*SGRD

STEMP ~ 190-T1A*TSC

SFE = JO-GRFE#FFSC

PSET (SFE,STEMP)

FOR J = 1 TO PMAX

FOR T2A = TP(J) + 273 TO

IF T2A ':•• TMAX THEN 2680

GOSUB 2000

TCOR = 390-T2A*TSC

FECOR = 10-GT2*FESC

LINE -(FECOR,TCOR)

NEXT T2A

NEXT J

- H(2)

- S(2)

TP(J-) 1) + 273 STEP 50

LOCATE 21

INPUT X*

RETURN

1

2999 SUBROUTINE TO SORT THERMODYNAMIC ENTRIES ACCORDING TO TEMPERATURE

3000 TP(1)-=25:K = 2

3010 FOR I - 1 TO Z

302.0 FOR J = 1 TO N(I)

3030 TF'(K) - T2(I,J)

3040 I' •- K + 1

3050 NEXT J

3070 NEXT I

3080 PMAX = K - 1

T.090 D - 0

3100 FOR I = 1 TO PMAX-1

3110 FOR h = I -i- 1 TO PMAX

3120 IF TF'(I)

 :' TP(!<) THEN 3150

3130 IF TP(I) - TP(K> THEN TP(K) =•

3140 SWAP TP(I),TP(K)

3150 NEXT I/

3160 NEXT I

3170 FOR I = 1 TO PMAX

3180 IF fPd) = 99999! THEN D = D + 1

3190 NEXT I

3200 PMAX = PMAX - D

3220 FOR I = 1 TO 3

99999':GOTO 3150
ORIGINAL PAGE IS

OF POOR QUALITY

3230

3240

3260

3270

5280

5290

3300

3310

3315

3499

7.5'">0

3510

3520

3530

3540

3550

3560

3570

5580

.-.590

36 On

J.610

3620

5630

3640

3650

3660

3690

3700

5710

3720

373 I'

3740

3750

376"

3770

3780

3790

3000

'.'.810

3820

3999

4000

-300

4O10

4020

4030

4040

4050

0:6QTO 3290

J = 1

FOR K = 1 TO PMAX

FOR C = 1 TO 4:AX(I,K,C) = A(I,J,C):NEXT C

IF TP(K-U) < T2(I,1) THEN HX<I,K)=0:SX<I,M

HX(I,K) = HP(I,J):SX(I,K) = SP(I,J)

IF TP(K-f-l) ':•= T2(I',J) THEN J--J + J

NEXT Y

NEXT /

STOP

RETURN

REM SUBROUTINE TO GRAPH SEVERAL REACTIONS ON ONE GRAPH

CLS

F*= "DATA":PRINT "ENTER NAME OF DATA FILE ";:1NPUT F*

INPUT "ENTER DISC DRIVE A OR B";D*

FILE* = D*+":"+F$+".DAT"

FOR CMP = 1 TO 10

PRINT "ENTER REACTION PRODUCT OR 0 FOR NONE";CMP;:INPUT RF$(CMP)

IF RP*(CMP) = "0" THEN 3580

NEXT CMP

NUM - CMP •- 1

INPUT "ENTER MAXIMUM TEMPERATURE FOR THESE CALCULATIONS"; TMAX

GOSUB 4010

TSC = 180/3000

FESC =•" 600/300000'

TOR CMP = 1 TO NUM

R$~ RP$(CMP)

SOSUB 950

T1A = TP(L) + 273

HGRD '-- M(3)*H(3) - M (1) *H (1) - H(2)

SGRD = M(3)*S(3) - M(1)*S(1) - S(2)

GRFE = HGRD - T1A*SGRD

STEMP = 19O--T1A*TSC

SFE •= 10-BRFE*FESC

F'SET (SFC, STEMP)

! OR 12A = T1A +• 50 TO TMAX + 273 STEP 50

GOSUB 2000

TCOR = 190-TSC*T2A

FECOR = ]0~FESC*6T2

LINE TM(FECOR,TCOR)

NEXT T2A

NEXT CMP

LOCATE 25, 3

TNPUT X*

RETURN

REM SUBROUTINE FOR GENERATING GRAPHIC FORM ON IBM PC SCREEN

T$=" -50 -100 (Leal) -150 -200 -250

II

CLS

SCREEN 2

LINE (10, 5)--(620, 190) , ,B

FOR Y = 1 TO 6

LINE. (5, J90-Y*30)-(12, 190--Y#30)
4060 LINE (615, 190-Y*30> - (620, 190-YK30)

4070 YV = Y*500

4080 LOCATE 25- Y*3. 9, 73: PRINT USING

4090 NEXT Y

4100 T$=" kcal --50 -100 -J 50 -2OD -25

0 -300 "

4110 FOR X = 1 TO 6

4120 LINE <10+X*100, 195) - (1O+X*100, 185)

4130 NEXT X

4140 LOCATE 25, 1:PRINT T*s

4150 RETURN