NBSIR 87-3601

High Temperature Chemistry of

Stored Chemical Energy

Reactions for Propulsion

L. P. Cook, E. R. Plante, D. W. Bonnell, and J. W. Hastie

U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

Institute for Materials Science and Engineering

High Temperature Chemistry

Ceramics Division

Gaithersburg, MD 20899

July 1987

Annual Report

U.S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANOAROS

NBSIR 87-3601

HIGH TEMPERATURE CHEMISTRY OF

STORED CHEMICAL ENERGY

REACTIONS FOR PROPULSION

L. P. Cook, E. R. Plante, D. W. Bonnell, and J. W. Hastie

U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

Institute for Materials Science and Engineering

High Temperature Chemistry

Ceramics Division

Gaithersburg, MD 20899

June 1987

Annual Report

U.S. DEPARTMENT OF COMMERCE, Malcolm Baldrige, Secretary

NATIONAL BUREAU OF STANDARDS. Ernest Ambler. Director
'
High Temperature Chemistry of Stored

Chemical Energy Reactions for Propulsion

Annual Report

For the Period May 25, 1985 to December 31, 1986

L. P. Cook, E. R. Plante, D. W. Bonnell, and J. W. Has tie

Ceramics Division

Institute for Materials Science and Engineering

National Bureau of Standards

Gaithersburg, MD 20899

March 25, 1986

Prepared for the Department of the Navy

Office of Naval Research

Arlington, VA 22217

Under Contract No: N00014-85-F-0144

APPROVED FOR PUBLIC RELEASE: DISTRIBUTION UNLIMITED

REPRODUCTION IN WHOLE OR IN PART IS PERMITTED FOR ANY

PURPOSE OF THE U.S. GOVERNMENT
2

HIGH TEMPERATURE CHEMISTRY OF STORED CHEMICAL ENERGY

REACTIONS FOR PROPULSION

Table of Contents

Abstract 3

I. INTRODUCTION 4

II. REACTION VERIFICATION 6

A. Equilibrium Among Predicted Product Phases 6

B. LiAlMg/C103 F 7

C. Thermal Decomposition of C103 F 9

i. Coupling of the Thermoanalyzer with a Mass Spectrometer . . 9

ii. Analysis of C103 F Decomposition Using High Pressure Sampling

Transpiration Mass Spectrometry 11

III. KINETICS 14

A. Reaction of A12 03 with C103 F 14

B. Reaction of MgO with C103 F 17

C. Reaction of Mg with C103 F 18

D. Reaction of Al with C103 F 18

E. Transpiration Mass Spectrometry (TMS) of the A1/C103 F Reaction. 21

IV. PHASE EQUILIBRIA 23

A. Condensed Phase Equilibria of the System Li2 0-Al2 03 23

i. Melting and Solid Solution Relations 23

ii. Solid State Transition in LiAl5 08 Spinel 25

B. Condensed Phase Equilibria in the System Li2 0-Al2 03 -A1F3 -LiF . 26

C. Thermodynamics of Competing Oxidation Reactions 27

D. Reactant/Product Vapor Pressures 31

V. DISCUSSION AND FUTURE DIRECTIONS 32

VI. REFERENCES 33

VIII. FIGURES 51

IX. DISTRIBUTION 53
3

HIGH TEMPERATURE CHEMISTRY OF STORED CHEMICAL ENERGY

REACTIONS FOR PROPULSION

Abstract

This report summarizes the results of a continuing study of the high

temperature chemistry of stored chemical energy reaction systems. The eight

fuel/oxidant reactions of interest (including several which are multistage)

are: Li/H2 0 ,

H

2 /02 ; Li/H2 0, Na02 /H2 0, H2 /02 ; MgAl/H2 0, H2 /02 ; LiAl/C103 F; LiAlMg/C103 F; LiBe/C103 F; Li/C^.F20 ; LiB/NF3

. Thermodynamic prediction of the

products of three of these reactions has been corroborated by equilibrating

postulated products at high temperature, while results from a fourth reaction

require modification of the reaction scheme originally proposed. Mass

spectrometric observations on the thermal decomposition of C103 F at elevated

temperatures are presented.

Thermogravimetric studies have been completed on the behavior of Al2 03 and MgO

in the presence of C103 F. Based on these data a new ceramic containment

system comprised of alumina and magnesia parts has allowed extension of

kinetic experiments from the 650° C limit previously encountered to a temperature in excess of 800° C. Using the new apparatus, we have observed the

relative inertness of the Al component of the fuel to oxidation by C103 F even

at 800° C. We have also noted the extensive vapor phase transport of LiF and

MgF2 , not expected on the basis of known thermodynamic data.

Thermogravimetric experiments have been completed on the oxidation of molten

aluminum droplets by C103 F. Rate data for this reaction indicate multiple

mechanisms, possibly including the following steps: (1) nucleation and growth

of A1F3 precipitation sites; (2) edge growth of A1F3 islands followed by

coalescence of islands; (3) diffusion limited thickening of the A1F3 layer.

Observations on the early stages of the Al/C103 F reaction have also been made

using high pressure sampling transpiration mass spectrometry.

Phase equilibrium experiments have continued on the product system Li2 0-Al2 0 3 in sealed Mo capsules, utilizing an improved high temperature equilibration

apparatus. Experiments indicate a previously undescribed degree of complexity

near the high alumina end, which may involve solid solution of Li2 0 in the

corundum structure, or an intermediate series of solid solutions or compounds

based on the LiAl5 08 spinel phase. The solid state phase transition in

LiAl5 08 has been studied by DTA; although the solid solution region is small,

the temperature of this transition ranges from 1269° to 1308° depending on

whether it is Al2 03 -saturated or Li2 0- saturated. In the C103 F-based reaction

systems, substantial entry of fluorine into the product LiAl5 08 spinel phase

is postulated.

Thermodynamic calculations have been completed to assess the importance of

vaporization over reactant/product solids and liquids. In a situation where

dissociated C103 F is flowing over molten alloys, fluoride products are thermodynamically most stable, followed by oxides, and finally by chlorides.

The chlorides in general have high vapor pressures, which may be enhanced by
4

polymerization. If passivating product layers of liquid or solid fluorides

are formed on metal reactants during C103 F oxidation, it would be expected

that chlorine and chlorides would be partitioned strongly into the vapor

phase, along with oxygen.

Future work is planned which will determine rate constants and temperature

dependencies for the kinetics of the oxidation of individual alloy components

by Cl2 , 02 and F2

. Phase equilibrium determinations will focus on the system

Li-Al-Mg-O-F, with special regard to the entry of fluorine into oxide phases.

I . INTRODUCTION

The present report describes results of our research on the chemistry of

liquid metal-based stored chemical energy propellants during the past

year. This work represents a continuation of work begun earlier and

described in two previous reports [1, 2], where extensive literature

searches were also reported. There are at least eight different stored

chemical energy propulsion (SCEPS) reactions involving various

fuel/oxidant pairs which are of interest. Several of these reactions

involve more than one stage. Reactions or reaction groups considered

are

:

2 Li ( 2 ) + H2 0(g) - 2 LiOH(i) + H2 (g)

'

( 1 ) H2 (g) + (1/2) 02 (g) - H2 0(g) y

2 Li (i) + H2 0(g) - 2 LiOH(i) + H2 (g)

(2/3) Na02 (c) + (1/3) H2 0(g) - (2/3) NaOH(c) + (1/2) 02 (g) ( 2 ) H2 (g) + (1/2) 02 (g) - H2 0(g) y

2 MgAl(i) + 5 H2 0(g) - MgO(c) + MgAl2 0 4 (c) + 5 H2 (g)

'

5 H2 (g) + (5/2) 02 (g) - 5 H2 0(g) y (3)

2 LiAl(i) + C103 F(g) - A12 03 (c) + LiF(c) + LiCl(i) ( 4 )
5

4 LiAlMg(i) + 3 C103 F(g) - MgF2 (c) + LiF(c) + 3 LiCl(i) + 2 MgAl2 0 4 (c) + MgO(c) (5)

8 Li(i) + 8 Be(c) + C103 F(g) - 8 BeO(c) + Li2 0(c) + 3 LiF(c) + LiCl(i) (6)

Ci iF20 (g) + 20 Li(i) - 11 C(c) + 20 LiF(c) (7)

2 Li(i) + LiB(c) + NF3 (g) - 3 LiF(c) + BN(c) . (8)

Preliminary kinetic data on many of these reactions have been presented

in an earlier report [2]; however results were limited to 650° C by

reaction of the experimental container materials with oxidant (usually

C103 F) and/or with liquid metal. In this report experiments up to 800°

C

are described.

Reference [1] has dealt with phase equilibria in the system Li2 0-Al2 03

. Phases on this join are products in several reaction schemes. In the

present report, additional data are presented for the high alumina end of

the system. We also discuss equilibration experiments on the

thermodynamically predicted reaction products in several of the reactions

(1) through (8). These experiments have led to the postulation of

extensive fluorine substitution in at least one oxide phase. Finally,

experimental results indicate the widespread importance of the gas phase

as a transport medium, and we report mass spectrometric measurements on

the gas phase, including the use of a high pressure mass spectrometry

system developed in this laboratory. Supplementing these measurements

are thermodynamic calculations of vapor pressures over products and
6

reactants at high temperatures for the various reaction schemes. Plans

for follow-up research are given in the concluding section.

II . REACTION VERIFICATION

A. Equilibrium Among Predicted Product Phases

Thermodynamically predicted products of various reactions from

ref. [2] are given in Table 1. Results of experiments on reactions (1),

(2), and (3) were given in ref. [2]; reaction (6) will not be

investigated experimentally due to the toxicity of beryllium. Because of

the kinetic and materials limitations indicated in this and previous

reports, it has not yet been possible to obtain direct data on reactions

(4), (5), (7), and (8) to test the thermodynamic predictions. An

indirect, though- inconclusive test involves heating mixtures of the

predicted products; if they do not react, this is consistent with the

equilibrium predictions; however this circumstance is not proof, as kinetic factors could impede the attainment of equilibrium. Predicted

products of reactions (4), (7), and (8) have been mixed together in equal

parts by weight and equilibrated. Experimental results are shown in

Table 2. These experiments were completed in a box furnace in sealed Pt

capsules. Specimens were removed from the furnace and cooled in air

(unless otherwise noted), then opened and x-rayed. Results for reactions

(4) indicate formation of a spinel phase resembling LiAl5 08 , at 1000°

C

and 1200° C; reaction (4) is therefore not correct as written. As the

alumina has vanished, and no other new phases are present, entry of

fluorine into the spinel phase is a possibility, perhaps as a solid

solution of the form Li^

+x

^AlAl^

x )^(8 2x)^2x* possibility will
7

be discussed further in Section IV-B. The implication of the formation

of oxyfluoride phases on the predicted energy yield of reaction (4)

cannot be assessed without additional thermodynamic data. Reactions (7)

and (8), however, may be correct as written, as the predicted products:

LiF + C, and LiF + BN, respectively, show no sign of reaction when

heated.

B. LiAlMg/ClO^F f reaction (5)]

In reference [2] we described experiments on the LiAl/C103 F reaction

pair, which were limited by the inability to exceed temperatures above

650° C, due to reaction of the molten fuel with the alumina; since that

time we have investigated the use of MgO as a container, and it appears

to function much better. The initial experiments done with this system

utilized an MgO cup, into which was placed a small (25 mg) coupon of

LiAlMg ternary alloy. The coupon was sliced from an ingot of alloy

prepared by induction melting of the elemental constituents under an

argon atmosphere in a tantalum crucible, followed by casting in a copper

chill mold. The sample was placed in a Mettler1 TA-1 thermal analysis

system on a magnesia substrate. First the sample was brought to a temperature of 800 °C under argon. As the temperature was increased,

relatively little weight change was noted, indicating that the activity

of the Mg component in the alloy was sufficiently lowered to prevent the

rapid volatization that would be experienced for pure Mg at this

1 Certain commercial equipment, instruments, or materials are identified

in this paper in order to adequately specify the experimental procedure. Such

identification does not imply recommendation or endorsement by the National

Bureau of Standards.
8 temperature (refer to Fig. 36). After temperature was reached, C103 F gas

was introduced at a constant flow rate of 2.5 cc/min. A rapid and

relatively constant rate of weight gain was observed, which abruptly

halted after approximately 1/2 hour. Upon examination of the charge, an

intergrown felt- like mass of acicular crystals rimming the cell was

observed. All that remained of the alloy coupon was a small metallic

button. X-ray diffraction analysis of the felted mass of crystals

indicated primarily MgF2 with lesser LiF. No x-ray evidence of aluminumcontaining phases was found in the crystalline mass. The metallic button

is assumed to have been highly enriched in aluminum (an analysis was not

possible). During this experiment a platinum gas feeder tube was used,

as this had worked well at 650° C. However at the 800° C temperature of

this experiment, platinum transport was observed and so subsequent

experiments used an alumina feeder tube for the C103 F (Section III-A).

The apparent transport of lithium and magnesium away from the reaction

site in the presence of C103 F or its dissociation products is not

predicted on thermodynamic grounds as the vapor pressures of the

thermodynamically most stable salts such as LiF and AlF3 are relatively

low at 800* C (see section IV-D) . A possible explanation is that kinetic

factors impede the development of a surface layer of the predicted

equilibrium fluorides of Mg and Li. Several possible reactions for

transport of Li and Mg based on known vapor species exist. Some of these

possibilities are indicated in Table 3 (alternative explanations, to be

examined in future work, involve possible formation of new vapor

complexes) . Metal vaporization does not appear to be the principal
9

mechanism, as there was not substantial weight loss from the ingot prior

to the time the C103 F flow was initiated. Metastable formation of

chloride species (including dimers, though these are not shown), is a mechanism that could lead to enhanced transport from the reaction site,

as the chlorides of lithium and magnesium both have substantially higher

vapor pressures than the fluorides (section IV-D) . The fact that

aluminum apparently did not migrate in this experiment may indicate the

relative ease of formation of A1F3

. Experiments described in a later

section (III-C) point up the effectiveness of a very thin layer of

crystalline A1F3 in preventing further reaction. Furthermore, A1F3 is

solid at the temperature of the experiment, whereas the fluorides of Mg

and Li are molten, and would presumably facilitate diffusion of metal

species to the reaction site.

C. Thermal Decomposition of C103 F

i. Coupling of the Thermoanalyzer with a Mass Spectrometer

Failure of the Pt transport tube initially used to pipe C103 F into the

hot reaction zone on the thermal analysis system occurred soon after the

first experiments were conducted at 800° C. Extensive thinning of the

tube due to Pt removal from the inside and apparent redeposition near the

exit point of the C103 F gas was observed. Formation of a platinum halide

species was therefore suggested, which in turn implies decomposition of

the C103 F gas. The platinum feeder tube was replaced by alumina, which

has performed much better. Observations suggest that a thin relatively

stable layer of microcrystalline solid A1F3 is formed on the surface of

the alumina, which prevents further reaction of the alumina. Crucibles
10

of alumina for the experiments with C103 F could thus be "presaturated" to

constant weight together with their MgO inserts (if used) at the

temperature of the experiment in flowing C103 F (this is discussed more

fully in Sections III-A, B) . Alloy starting materials were then added

and the alloy reaction with C103 F studied as outlined above in

Section II-A. Formation of fluoride reaction products in these

experiments with apparent lack of any oxide phases suggested that- only

selected species within the gas phase were reacting, again raising the

possibility of thermal decomposition of the C103 F. According to the

literature (refs. [3, 4]) C103 F does not decompose up to the softening

point of glass (e.g. 820°C for type 7740 Pyrex) , even though it is

thermodynamically unstable above 25° C, according to data from JANAF [5].

In order to gather evidence for gaseous decomposition products, a leak

valve was installed in the exhaust line of the thermal analysis system

and a small portion of the exhaust gas was bled into the source of a modulated beam mass spectrometer system. Separate experiments with C103 F

at room temperature indicate that electron bombardment at 30 eV forms the

parent and fragment ions, in order of decreasing intensity, C103 +

, C102 +, C10+

, C103 F*, and Cl* . These ions, with the exception of the parent

C103 F*, are a typical fragmentation pattern expected from electron impact

with C103 F parent molecules.

Fig. 1 shows ion intensities as a function of temperature scaled using

the ^Ar* intensity as a reference (normalized to 100) . These

observations were made after the prefluorination reaction had taken place
11

as indicated by the constancy in mass of the alumina cell. There is a

large change in 02 + intensity between 500 and 700° C. Also to be noted

are the signals due to Cl2 + and C1F+ at 700° C. Near 500° the Cl2 + and

C1F+ signals are very weak, and signals due to the normal fragmentation

pattern of C103 F dominate the spectrum. Our interpretation of these data

is that thermal decomposition of C103 F takes place between 500 and 700° C.

The formation of Cl2 + and C1F* probably is due to recombination of Cl

and F formed in the decomposition reaction, as they are not normally

formed by fragmentation of C103 F. Also, the unusual behavior of the

higher temperature part of the C10+ curve would be consistent with it

being formed from recombination of decomposition products.

ii. Analysis of C103 F Decomposition Using High Pressure

Sampling Transpiration Mass Spectrometry

We have developed in our laboratories a high pressure sampling mass

spectrometric instrument for studying gas/solid interactions [ 6] . This

instrument couples the classical transpiration method with a molecular

beam mass spectrometric analysis of the reaction vapor species. In this

technique, also known as transpiration mass spectrometry (TMS) , gases

formed in the reaction zone are expanded through a nozzle into a high

vacuum system, where gases in the beam are mass analyzed [Fig. 2] . The

expansion through the nozzle leads to the formation of a beam with a frozen vapor species composition representing the equilibrium or steadystate concentrations present the reaction cell.
12

A significant advantage of use of the TMS system over the classical

Knudsen effusion method is that it allows measurements to be made at

pressures, approaching one atmosphere. This pressure region is much

closer to that present in operating propulsion systems. Because of beam

dynamics and the relatively high background pressures in the mass

spectrometer section of the system, reactor pressures generally need to

• 4 be in the range 10 atm and above before they can be observed. The

system is usually operated as a fixed flow system and the flow rate as well as the total pressure are monitored during the experiment. The

measured total pressure and mass spectral ion intensity of the carrier

gas can be used to calibrate the system sensitivity and to determine the

partial pressures of other species formed in the reaction cell, as described in ref. [6].

The thermal decomposition of C103 F, as noted in section (i), leads to

problems in data interpretation because of the possible recombination

processes that may take place between the thermal analysis system and the

mass spectrometer detector. The relatively long transit time between

decomposition and detection is effectively eliminated by using the

sampling system.

The decomposition of C103 F was observed in the TMS system by introducing

C103 F into a fused silica transpiration reactor using argon as the

carrier gas . The data obtained from these measurements is shown in

Fig. 3 where the lines shown represent what we would expect for an

experiment in which the scatter in the data is averaged out. The actual
13

data have considerable scatter owing to technical problems resulting from

decreases required in the flow rates initially selected in order to

maintain the pressure in the optimum range. The change in flow rates

results in relatively long time lags before the gas composition has had

an opportunity to shift to new composition values because of the

relatively small flow rate and large volume of the system.

The appearance of Cl2 and 02 as indicated by the ions Cl2 + and 02 +

, together with the concomitant disappearance of C103 F

+ and its fragment

ions, indicates the decomposition of C103 F in the temperature range of

37 35

400-600°C. Comparison of the C103 + and C103 + isotopic ion

intensities indicates formation of an additional species of the same mass

37 _ of 85/i (mass units) as C103 + at temperatures above about 400°C. The

28

most reasonable assignment for this species is SiF3 + which arises from

SiF4 produced by reaction of F2 with the silica reaction cell. This

species accounts for the apparent absence of F2 as a C103 F decomposition

product, whereas Cl2 and 02 are observed. It can be noted that several

ions (C1F+ and C10+

) observed in the thermoanalyzer mass spectrometer

experiment were not observed in the TMS measurements which indicates that

these species were probably formed by reaction of decomposition products

during the relatively long transit time from the thermoanalyzer to the

mass spectrometer system.

Complementary TMS data were obtained in the absence of a carrier gas. As

noted above, the total pressures observed at constant flow rate are generally monitored during the measurements . These data also indicate
14

thermal decomposition of C103 F in a similar temperature region to that

noted in the Ar carrier gas experiments, as shown in Fig. 4. For a nondecomposing gas, a plot of pressure versus temperature will give a straight line whose slope is related to the number of moles per unit time

flowing through the system. Note that in Fig. 4 there is a break in the

curve near 530° C, with pressures below and above this temperature being

represented reasonably well by straight lines. The ratio of the slopes is

2.8 which is reasonably close to the ratio of the number of moles of gas

of the products to reactants for the reaction,

4 C103 F(g) + Si02 (fused quartz) = 2 Cl2 (g) + 7 02 (g) + SiF4 (g)

.

At the same time the pressure- temperature data was obtained the ion

current from 35 C103 + was observed. These data are plotted in Fig. 5.

The scatter in the low temperature region of the curve is a presently

unexplained phenomenon which is apparently a result of changing the

temperature

.

III. KINETICS

A. Reaction of A12 03 with C103 F

Upon failure of a Pt feeder tube used for the C103 F, it was decided to

test high purity alumina as a replacement, as this is commercially

available in tubing of several sizes. To establish the long term

behavior of Al2 03 in flowing C103 F at high temperature a series of

thermogravimetric experiments was carried out. First it was noted that

unused alumina crucibles could be heated to nearly constant weight in
15

flowing C103 F (see Fig. 6). Windowless SEM/EDX analysis revealed the

presence of a coating of faceted crystals giving a strong fluorine

signal. This was interpreted as indicating development of an AlF3 coating. Presumably once formed this coating served as a diffusion

barrier against further reaction. Assuming uniform formation of AlF3 on

the inner surface of the alumina crucible of Fig. 7 an estimate of film

thickness formed at 800° C would be about 10 /im.

To further explore the stability of Al2 03 in flowing C103 F, experiments

at temperatures from 450° to 800°C were conducted using 0.3 fim powders of

Linde A alumina (99% corundum). Results are shown in Fig. 7 and Table 4.

In these experiments, the samples were first brought to temperature and

then the gas was introduced. X-ray powder diffraction analysis of the

product indicated only AlF3

. From Table 4, it can be seen that as the

temperature reaches 700° C the weight gain approaches the theoretical

value of 64.7% for complete conversion of the alumina powder according to

the reaction:

A12 03 (c) + 3 F2 (g) - 2 A1F3 (c) + 3/2 02 (g) .

The effect of varying the rate of C103 F flow over the powdered alumina at

800°C is shown in Fig. 9. Although the rate of reaction, and hence the

slope of the reaction curves vary, all show a well-defined reaction end

point, which occurs at a weight gain of 93-94% of that for complete

conversion to AlF3 (see Table 5). A substantial part of the reaction
16

curves in Figs. 7-9 can be approximated by a parabolic rate law of the

type:

O’

kt

where W/A is the mass gained per unit area available for reaction , k is

the rate constant and t is the cumulative reaction time. Calculated rate

constants for the data in Figs. 8 and 9 are given in Table 6, and the

portions of the data which have been fitted in this way are indicated in

the illustrations . Note that the early portions cannot be fitted in this

fashion; the reason for this is not clear, but it may have to do with

nucleation and growth of AlF3 product. The point at which the powdered

alumina is consumed (reaction end point) is obvious on Figs. 8 and 9. In

the lower temperature (450-600°C) experiments in Fig. 7, where a reaction

end point is not observed, the rate constants show an Arrhenius

relationship, as illustrated in Fig. 9. The equation of the line is

log k = 7.63 - 7 . 06xl03 /T(K)

.

Above 600° this relationship is not followed, although the higher- flow

rate experiments give k's which lie closer to the Arrhenius line. This

implies that above 660° C, under the given experimental conditions, the

supply of C103 F to the reaction interface may be the rate limiting factor

for these high surface area experiments. It should be noted that the

initial surface area used in plotting Figs. 7 and 8, based on information

provided by the manufacturer of Linde A, was 10-18 m

2 /g; an average of

14 m

2 /g was used. In practice, this value may have been appreciably

reduced as the sample heated up and as the reaction proceeded. This is

also indicated by an attempt to calculate the thickness of the reaction
17

layer on the powders , which gives a value a factor of 10 too low to be

consistent with the nearly complete reaction of the 0.3 /im powders, as observed above 600° C.

B . Reaction of MgQ with CIO^ F

In a later section (IV-C) we describe the results of thermodynamic

predictions for the interaction between MgO, Cl2 and F2. The net result

is that MgF2 should form at the expense of MgO. Experiments were

conducted on the thermoanalyzer to assess the importance of these

reactions in the presence of C103 F (or its dissociation products) at

800° C.

Results of an experiment using a coarsely crystalline MgO cell are shown

in Fig. 10, which indicates a "saturation" effect similar to that

described above for Al2 03

. Presumably this is due to formation of a thin

layer of MgF2 which impedes further reaction, according to:

MgO(c) + F2 (g) - MgF2 (c) + (1/2) 02 (g)

Results obtained for crucibles fabricated of dense, polycrystalline

sintered magnesia are similar. Experiments in which the flow rate of

C103 F was varied during saturation of a polycrystalline cell show a nearly linear correlation between flow rate and rate of reaction. For

the coarsely crystalline cell the calculated thickness of the MgF2 layer

after 1 hour, is approximately 2 /xm. As indicated, the final part of the

data in Fig. 10 fit a parabolic rate law.
18

C. Reaction of Mg with CICU F

A thermogravimetric experiment was attempted in which Mg metal was heated

to 800° C, preparatory to reaction with C103 F. However the vapor pressure

of Mg metal at temperatures above its melting point is such that

significant evaporation occurs at the metal surface (see section IV-D)

,

and for this reason it was not possible to complete the experiment at

800° C. To minimize metal vaporization and obtain meaningful data-, it may

be necessary to complete future experiments at temperatures only slightly

above the melting point of Mg (650°C).

D. Reaction of Al with C10? F

Once it was established that the C103 F decomposed at elevated

temperatures, that the individual components of the Al-containing alloys

react somewhat independently, and that Al does not react to the same

degree as the other metal components, it was decided to focus more

specifically on the problem of Al reaction by working with the pure

metal. For quantitative reproducible kinetic studies, the following

requirements are essential: minimization of experimental geometry

effects; and constancy or quantification of relevant variables such as surface temperature, surface area, oxidant flow rate and ambient

pressure. Surface area was made constant by selecting high purity

aluminum- shot pieces of similar weight. It was found that these formed a nearly spherical ball (Fig. 11) in the Al2 03 crucible when melted, giving

relatively constant surface area. During C103 F experiments at 800° C, all

Al droplets showed a "frosting'' of the surface, which at higher

magnification in the SEM proved to be a dense interlocking mass of well-
19

faceted crystals (Fig. 12). SEM/windowless EDX showed Al and F,

suggesting A1F3

.

In the Al reaction experiments the proximity of the C103 F flow tube to

the reaction surface was important. In the case where the exit port was

-10 mm from the surface of the molten Al droplet, a tear- shaped channel,

free of surface salts was formed, regardless of flow rate (Fig. 13).

When the exit port was moved to -15 mm from the surface, then no such

salt- free channel was formed, although the surface of the ball had slight

creases directly under the exit port. The reason for the salt- free scar

at the close-in geometry is not clear. It is tempting to suggest a physical effect associated with the velocity of the inlet gas, however,

this would be ordinarily thought to result in increased formation of salt

so that any physical disturbance of the surface of the Al would be

rapidly covered over by salt crystals (e.g., as seen in Fig. 12). The

deep scar shown in Fig. 13, typical of experiments at the close-in

geometry, is suggestive of removal of material from the surface of the

Al. This would require both local formation of a volatile Al species and

local suppression of the salt formation (presumably A1F3 ) seen on the

rest of the surface. A possible chain of events at the close-in geometry

might be (assuming dissociation of the C103 F):

(3/2) Cl2 (g) + Al(i) - AlCl3 (g) (13)

AlCl3 (g) + (3/2) F2 (g) - A1F3 (c) + (3/2) Cl2 (g) (14)

with the solid being precipitated away from the high flow area on the

droplet surface. Hopefully this possibility can be tested using

transpiration mass spectrometry.
20

Thermogravimetric rate data for reaction of liquid Al with C103 F at 700,

750 and 800°C are shown in Fig. 14 and summarized in Table 7. The flow

rate was nominally 1 seem. The shapes of the three curves in Fig. 15 are similar, but the amplitude (total wt. gain of the Al droplets) increases

by a factor of about seven going from 700 to 850° C. The highest total

weight gain (800°C experiment) is nonetheless small (2.75 mg) by

comparison with a typical droplet weight (415 mg)

.

The effect of flow rate on reaction of C103 F with Al at 800° C is shown in

Fig. 15 and summarized in Table 8. At the highest flow rate the shoulder

in the curve is considerably rounded and the slope leading up to it is

steeper relative to the two lower flow rates.

The curves in Figs. 14 and 15 are somewhat more complex than the

Al2 03 /C103 F curves of Figs. 7 and 8. Preliminary interpretation can be

made in terms of three different processes, each dominant in a different

area of the curve: (a) initial region: nucleation and growth of AlF3 reaction sites; (b) middle region (nearly linear, to parabolic as shoulder is approached) lateral growth of AlF3 islands at their edges,

followed by merging of islands and complete coverage of the surface;

(c) final region (parabolic) : thickening of dense AlF3 film by diffusion

through the film. A summary of the mathematical analysis of the data is

given in Table 9.
21

E. Transpiration Mass Spectrometry CPIS’) of the A1/C103 F Reaction

In measurements described in ref. [2], in which we examined the behavior

of pure Al metal with C103 F using a gas entry Knudsen effusion method,

the masses identified were AlF* , A1C1+

, A1F2 +, A1C1F* , A1F3 +

, A1F2 C1+, A1C12 F

+

, and A1C13 +

. The period during which aluminum halide species

were generated was quite short and the fraction of the sample which

reacted was small. It was presumed that the sample became less reactive

with time because of formation of either an Al2 03 or an A1F3 surface

layer.

More recently, we have carried out TMS measurements on the Al/C103 F

reaction. These experiments were carried out in the absence of a carrier

gas. A fragment of pure Al shot was placed in a MgO boat inside the

fused silica transpiration cell. C103 F was introduced, and the product

gases were analyzed mass spectrometrically . Ion intensities at 729° C are indicated in Table 10. Aluminum bearing vapor species were observed from

667 to 736° C. All of the ions identified in the Knudsen experiment with

the exception of A1F3 + were detected; the vapor concentration of AlF3 (g)

in the above temperature range would be below the detection limits of the

mass spectrometer. Also 02 +

, Cl2 + and SiF3 + were observed during this

period. The experiment was terminated because a significant decrease had

taken place in all the ion signals as well as the total pressure. This

behavior is not presently understood because the total pressure should

have remained at least as high as that due to decomposition of C103 F

unless erosion of the expansion nozzle took place or the unblocking of a partially blocked nozzle took place.
22

It seems clear from the results of this experiment that the reaction of

Al with C103 F takes place to a greater extent than was observed in the

Knudsen effusion case at lower pressures. The remaining sample was

removed from the magnesia cell at the conclusion of the experiment and

observed to be covered with a white layer. An SEM examination of the

surface deposit showed it to consist of columnar crystals aligned at

right angles to the reaction surface. A windowless EDX spectrum .showed

the presence of oxygen, but no fluorine (fluorine was observed in the

very top surface layer, however). Aluminum was the dominant constituent,

with minor amounts of Mg (from the boat) and Si (from the silica cell).

Apparently Al2 03 is the principal reaction product which implies that the

fluorine activity has locally been reduced near the surface of the Al,

thus suppressing the formation of the more stable A1F3

. A likely

explanation is reaction of the fluorine component of the oxidant with the

silica of the outer reaction cell; this is consistent with observation of

silicon fluoride species in the mass spectrum of the exiting gases.

Future experiments will utilize a different material for the outer cell.

It is hoped that such experiments will also allow closer observation of

any kinetic factors influencing the formation of aluminum chloride or

fluoride species.

IV. PHASE EQUILIBRIA

A. Condensed Phase Equilibria of the System Li2 0-A12 Q3

i. Melting and Solid Solution Relations

Experiments, primarily on the Li2 0-rich end of the system Li2 0-Al2 03 , were described in Ref. [1]. Many problems remain unresolved on the high
23

alumina end of the system. Alumina-rich compositions are important for

several reasons ; they encompass reaction product phases , including LiAl02 and LiAl5 08 ; the thermochemistry of these phases has implications for

calculations of energy yield; as products of high stability, they have

potential materials applications. The major challenge in working with

these materials is the high temperature of the relevant equilibria,

coupled with the non-quenchability of the samples. We have developed and

refined a high temperature apparatus and methodology for dealing with

these problems, as follows.

After homogenization, powdered mixtures were loaded into Mo capsules in a

drybox, followed by sealing with a carbon arc welder. Samples (up to

eight at a time) were then suspended in a Mo bucket in the hot zone of a tungsten furnace. Temperature was measured with a reinforced

W3%Re/W25%Re thermocouple calibrated against the melting points of Pd and

Pt and inserted into the Mo bucket in the center of the ring of samples.

Generally calibrations were within 5 to 10° C of the correct melting

points. Thermal gradients along the length and diameter of the holder

were less than 5°C and so total uncertainty in the temperature is near

±15°C to ±20° C, including control variation of ±5°C. Temperature was

controlled via a second thermocouple in the base of the furnace.

Experiments were terminated by allowing the furnace to cool (a typical

cooling curve is shown in Fig. 16). Although cooling at this rate is not

"quench" , it is rapid enough to preserve many of the high temperature

textural relationships. Following the experiments, the capsules were

opened and products were examined by scanning electron microscopy.
24

Generally it was possible to differentiate solids which were in

equilibrium at the temperature of the experiment by their size

(5 to 10 /im) and their well -developed facets. Crystals in equilibrium

with melt tended to be somewhat larger than those formed in the absence

of melt. Melts, if present, generally occupied the interstices between

such crystals, and their microcrystalline descendants could be readily

identified as in Fig. 17. Given the fact that the rate of cooling was

not "quench" , the crystallization history of such melts must be

considered in making interpretations. For example the melt phase in

Fig. 17 probably crystallized eutectically . Situtations where rims of

material have crystallized in an oriented fashion around the larger

grains may possibly indicate a peri tec tic, whereas in equigranular

,

porous specimens with sharp grain boundaries, melt was apparently never

present. Using data of this sort the diagram in Fig. 18 was developed.

The apparent lack of melting at temperatures below 1950°C for Al2 03 -rich

compositions could mean either presence of a compound intermediate

between LiAl5 08 (most probably with incongruent melting), solid solution

based on alumina, or possibly both. There is no x-ray evidence for solid

solution or intermediate compounds; hence it is postulated that if such

phases do exist they are unstable at lower temperatures, and decompose to

a mixture of lithium spinel and corundum. Micros true tural evidence for

such decomposition is seen in the lamellar structure of Fig. 19.

ii. Solid State Transition in LiAls 08 Spinel

At lower temperatures the LiAl5 08 spinel phase undergoes a phase

transition apparently related to ordering of Li and Al on the octahedral
25

spinel sites. A Rietveld refinement of the structure of LiAl5 08 based on

neutron diffraction data was given in reference [1]. This indicated

essentially complete ordering of Li and Al in the octahedral sites, with

no tetrahedral Li. Although this specimen had been equilibrated at about

1600°C, apparently it was not cooled rapidly enough to freeze in the

disordered state. Hence we still do not have good structural data on the

high temperature disordered stage. During the past year, experiments

were conducted on compositions from 50 to 100 mole% Al2 03 , to study in

more detail the postulated order/disorder transition in LiAl5 08

. The

phase transition was observed to be reversible (Fig. 20). Upon cooling,

the transition was relatively sluggish and required supercooling of about

25° C for initiation of the reaction at 1280° C which then apparently

continues down to 1090° C. Upon heating, a well-defined single thermal

event was seen. The values of the heating event were used to define the

temperature of the transition, as described in Ref. (1). Nine

compositions were studied; temperatures of the transition were constant,

but different on either side of the spinel composition (see Fig. 21).

This implies that a slight degree of solid solution in the 1:5

composition exists, which nevertheless has a very pronounced effect

(nearly 30° C) on the transition. The effect of annealing at temperatures

above and below the phase transition on the x-ray powder pattern is

manifested in the intensity ratios of several of the lines, which is

consistent with an order/disorder transition.
26

B . Condensed Phase Equilibria in the System Ll2 0-A1-, 03 -A1F3 -LiF

As noted above in Section II -B, experiments to verify the products of

reaction (4) suggested the existence of a spinel phase containing

fluorine. Several experiments have been conducted to follow up this

possibility, which is of both crystal -chemical interest and also of

importance to the rheological properties of predicted solid/liquid

products. Assuming that there are no anion vacancies, fluorine

substitution can be plotted in the ternary reciprocal system

Li , Al//F,0.

Experiments on the compositions plotted in Fig. 22 have been completed at

1200° C in the system. The purpose of these experiments has been to

locate a single-phase region of fluorine-substituted spinel. Evidence

for lack of the expected degree of melting at 1200° C in most compositions

on the Li2 0-rich side of the LiF-Al2 03 join in the ternary reciprocal

system Li2 0-Al2 03 -A1F3 -LiF comes from: visual observation, SEM high

magnification examination, and powder x-ray diffraction data. Since the

minimum melting temperature along the join LiF-AlF3 is 710° C, it would be

expected that fluoride phases would be present as melts at the

experimental temperature. The x-ray data are somewhat ambiguous; nearly

all experimental results give weak lines at positions corresponding to

the major lines for LiF and Li3 AlF6

. Possible explanations include:

(1) small amounts of unreacted salt; (2) small amounts of equilibrium

melt; (3) superstructure lines which happen to fall at the LiF and

Li3 AlF6 positions. Possibility (2) is judged most likely. On the basis

of intensities of LiF and Li 3 AlF6 lines, compositions near
27

75(2LiF. Al2 03

) : 25(LiAl5 08 ) are nearly single phase. Results of SEM

examination of a series of 1200° C quench experiments along the join

LiAl5 08

- (LiF.Al2 03 ) indicate that with increasing LiF concentration, the

fraction of well-faceted spinel crystals increases until at

75 (2LiF. Al2 03

) : 25(LiAl5 08 ) the sample is comprised almost entirely of

well-faceted spinel crystals (Fig. 23-a). On the other hand, at the

2LiF. Al2 03 composition, evidence for a melt is clear at high

magnification (Fig. 23-b). The interpretation of the SEM and x-ray

observations is summarized in the 1200° C isothermal phase diagram of

Fig. 24.

C . Thermodynamics of Competing Oxidation Reactions

Some experimental observations made during this work indicated that

selective reactions were taking place. For example, C103 F reaction with

a Li/Al alloy tended to form only halides with no indication of oxide

formation. Also, during reaction for C103 F with a Mg alloy, MgF2 (c) was observed to have been transported to the side of the reaction crucible

even though the vapor pressure of MgF2 was too low to account for the

transport at 800° C. A possible explanation is that transport was due to

MgCl2 which condensed and underwent a halide exchange reaction with F2

. This is evidence that, at least under laboratory conditions, the paths of

the chemical reactions are being governed by both thermodynamic and

kinetic factors.

To investigate these processes we considered the known thermodynamic data

governing these reactions. For purposes of this discussion we will
28

categorize reactions based on the standard Gibb's energies of formation

of the halides and oxides into the following types:

(a) interaction of chlorides and fluorides with metals;

(b) interaction of oxides with fluorine or chlorine;

(c) reaction of chlorides with fluorine;

(d) interaction of chlorides with fluorides;

(e) interaction of oxides with fluorides;

(f) interaction of oxides with chlorides.

Data for these types of reactions are listed in Tables 11 through 16.

The tables list the Gibb's energy of the reactions, as written, in

calories for temperatures from 800 through 1300 K respectively. As

usual, positive free energies indicate that the reactants are the

predominant materials present at equilibrium and negative free energies

indicate that the products are the predominant materials present. The

state selected for the individual substances was based on vapor pressure,

melting point and phase equilibrium considerations. Thus, it was assumed

that A1C13 and BeCl2 would be present as gases, that most of the halide

reaction products would be liquids, and that oxides except for Li2 0 would

be present as solids. Effects due to the possible formation of mixed

halide species such as A1C1F2 have been ignored in the present

calculations

.

Data in Table 11 correspond to the displacement of a metal from a less

stable metal halide to form a more stable metal halide. From the

reactions considered it is clear that if equilibrium was maintained
29

during the reaction the metals would be consumed in the order:

Li>Mg>Be>Al

.

Results in Table 12 show that none of the metal oxides are

thermodynamically stable in the presence of F2 (g) while only the

relatively reactive Li2 0(i) is unstable in the presence of Cl2 (g).

Table 13 shows that none of the chlorides are stable in the presence of

fluorine and will be converted to fluorides, while Table 14 expresses

possible interaction reactions among chlorides and fluorides.

Tables 15 and 16 list possible equilibria for oxide -fluoride and oxidechloride reactions. These data show which oxide-halide couples are stable or unstable. For example, Al2 03 will not react with BeF2 , LiF, or MgF2 ; BeO is resistant to LiF; and MgF2 and MgO are resistant to LiF. On

the other hand, MgO is not resistant to AlF3 or BeF2 , BeO is not

resistant to A1F3 , and Li2 0 is not resistant to any of the fluorides.

The tabular data can also be represented graphically as in Figs. 25-30.

In Fig. 25, for example we consider possible chemical equilibria of

chlorides formed by reaction with a 33%Mg - 33%Li - 33%Al alloy. For the

calculation, activities of Mg and Li metal are set equal to the mole

fractions and Al is treated as a diluent while it is assumed that the

activity of LiCl is 0 . 1 , 0 . 5 , or 0 . 9

.

We then calculate the ratio of the

activities of MgCl2 /LiCl as a function of temperature. The calculated
30

- - / activity ratio varies from 10 to 10 showing that given this set of

conditions and assuming thermodynamic equilibrium, essentially no MgCl2 is formed until all of the Li has reacted to form LiCl. In Fig. 26 the

same system is considered with regard to the chlorides of Mg and Al

(Li is treated as a diluent) ; as indicated, the result that the

-23 -15

MgCl2 /AlCl3 ratio varies between 10 and 10 . Thus, the Li/Mg/Al

alloy system would react with Cl2 to form first LiCl followed by MgCl2 and finally A1C13 (g) . The results of similar calculations for fluoride

reactions in this alloy system are shown in Fig. 27 and 28. Fig. 27

shows that LiF is formed preferentially over MgF2 while Fig. 28 shows the

preferential formation of LiF over AlF3

. Again, as with the chlorides,

the order of fluorine reaction in a system at thermodynamic equilibrium

would first consume all Li followed by Mg and finally Al. Figs. 29 and

30 demonstrate that LiF and MgF2 will be formed in preference to LiCl and

MgCl2 even if Cl2 (g) is present at much higher concentrations than F2 (g).

To summarize, formation of oxides will be negligible in the presence of

F2 until all the fluorine has been used up. Next, oxides will form if

thermodynamic equilibrium is achieved. Note that generally this is not

what we have observed in laboratory studies but this probably means that

the activation energy necessary to form the oxides is not achieved in the

temperature region we are obtaining. Finally chlorides will be formed.

However, note that the thermodynamic data predicts that only Li2 0 will

react with Cl2 (g). Thus, these calculations suggest that there may be

problems in obtaining relatively complete or uniform combustion.
31

D. Reactant /Product Vapor Pressures

It is necessary to consider vapor pressures of reactants or expected

products formed in the various combustion systems. In the case of a Li/Al or Li/Mg alloy with which water is reacted, the Li in the condensed

phase could absorb H2 to form LiH. Fig. 31 shows the H2 pressure over

pure LiH(i) based on data from the JANAF tables [5]. These data assume

that both Li and LiH(i) are pure phases. In reality Li dissolves to some

extent in the LiH(i) so that the pressure is actually less than this

estimate. Note that the H2 pressure is close to an atmosphere at 1200 K.

The effect of a second alloying element might decrease this pressure and

the Li activity might be decreased by as much as a factor of two. In

spite of this, Li alloy at lower temperatures might absorb a significant

fraction of the H2 produced thus reducing the amount of H2 available for

reaction.

Fig. 32 shows that LiOH(g) could present a transport problem in reactions

(1) and (2). Also it could be significant that the water pressure over

LiOH at 1300K approaches one atm, raising the possibility of producing

Li2 0, and thereby increasing the energy yield. By contrast, Fig. 33

indicates that the pressures of LiCl and LiF are to low to be relevant to

transport processes by vaporization.

Data shown in Fig. 34 for the Al halides indicates that very high

pressures could be established by A1C13 (g) . JANAF[5] reports a critical

temperature of 620 K and a critical pressure of 24.3 atm. Our

measurements show the formation of mixed halide vapors formed by the
32

reaction of C103 F with Al metal. JANAF tabulates data for some of the

mixed halide species. This problem will receive further consideration in

subsequent studies.

Fig. 35 shows the BeCl2 , Be2 Cl4 , and BeF2 vapor pressure curves. As with

A1C13 , the vapor pressure of BeCl2 will be very high at 1200 K.

Estimates based on the JANAF[5] tabulation indicate a pressure of> 90 atm

at 1200 K.

In Fig. 36 vapor pressure data for Mg(g) , and MgCl2 are represented. The

pressure of Mg(g) is about 0.2 atm at 1200 K.

V. DISCUSSION AND FUTURE DIRECTIONS

It is apparent that in dealing with the complex high temperature

chemistry of the multicomponent kinetic processes occurring during the

stored chemical energy release reactions discussed here, it is necessary

to consider the reaction behavior of the component pairs individually

(e.g., Al/F2 , Al/Cl2 , Al/02 , Mg/F2 , Mg/Cl2 , etc.) In future studies,

rate data will be collected as a function of temperature for these basic

reactions

.

Phase equilibria, especially melting, determine to a large degree the

properties of reaction products. Phase equilibrium measurements will be

initiated on the system Li-Mg-Al-O-F to explore further the possibility

of oxy- fluoride phase formation.
33

A few comments concerning importance of vapor pressures in these

propulsion systems should be made. In most of these systems where

individual chloride and fluoride species are present, additional complex

species each containing chlorine, fluorine and one or more metals may be

formed leading to higher pressures than have been calculated here. The

phenomenon of volatility enhancement by vapor complexing has been

discussed in detail elsewhere [7]. Also, the temperature in the flame

region of the device will likely be much higher than 1200 K leading to

much higher pressures in the flame region. Since the walls of the device

are cooler, condensation and vapor entrapment of fuel is a possible

problem area. Hence, additional experiments are planned using high

pressure transpiration mass spectrometry to identify the various species

formed and to measure their partial pressures as well as to. examine the

role of kinetic factors in gas phase transport.

VI. REFERENCES

1. L. P. Cook, E. R. Plante, R. S. Roth, and J. W. Hastie, 1984, "Phase

Equilibria of Stored Chemical Energy Reactants", National Bureau of

Standards Report No. NBSIR 84-2940, 103 p. (1984).

2. L. P. Cook and E. R. Plante, 1985, "Survey of Alternate Stored

Chemical Energy Reactions", National Bureau of Standards Report No.

NBSIR 85-3282, 106 p. (1985).

3. M. C. Sneed, J. L. Maynard, and R. C. Bras ted, "Inorganic

Chemistry", D. Van Nostrand Company Inc., New York, N.Y.

,

Vol. 3,

p. 29 (1954).

4. A. Engelbrecht and H. Atzanger, Monatsh. .83, p. 1087 (1952).

5. JANAF Thermochemical Tables, 2nd Ed., NSRDS-NBS 37, Washington, D.C.

(1971).
34

6. D. W. Bonnell and J. W. Has tie, Transpiration Mass Spectrometry of

High Temperature Vapors, p 357, in "Characterization of High

Temperature Vapors and Gases", J. W. Hastie, ed. ; NBS SP 561/1 and

2, U.S. Govt. Printing Office, Washington, D.C. (1979).

7. J. W. Hastie, "High Temperature Vapors", Acad. Press, New York,

p. 480 (1975).
35

Table 1. Thermodynamically Predicted Product Phases for SCEPS Reactions

Reaction Predicted Products

(initial stage or stages)

(1) Li/H2 0, H2 /02 LiOH, H2

(2) Li/H2 0, Na02 /H2 0, H2 /02 LiOH, H2 , NaOH, 02

(3) MgAl/H2 0, H2 /02 MgO, MgAl2 0, , H2

(4) LiAl/C103 F Al2 03 , LiF, LiCl

(5) LiAlMg/C103 F MgF2 , LiF, LiCl, MgAl2 04 , MgO

(6) LiBe/C103 F BeO, Li2 0, LiF, LiCl

(7) Li/Ci iF2 q C, LiF

( 8 ) LiB/NF3 LiF, BN
36

Table 2. Experimental Test of Thermodynamically Predicted SCEPS

Product Phases

Reaction

Starting

Materials

Temp

.

(°C)

Time

(hr)

X-ray Analysis

of Results

(4) LiF, LiCl , Al2 03 600 48 LiCl, LiCl H2 0*

Al2 03> LiF

(4) LiF, LiCl, Al2 03 800 23 LiCl, LiCl H2 0*

,

AI2O3 > LiF

(4) LiF, LiCl ,A12 03 1000 23 LiCl, LiF, LiAl5 08

(4) LiF, LiCl, Al2 03 1200 116

(quenched)

LiCl, LiCl H2 0*

LiF, LiAl5 08

(7) LiF, C 1200 24 LiF, C

(8) LiF, BN 600 18 LiF, BN

(8) LiF, BN 800 24 LiF, BN

(8) LiF, BN 1000 22 LiF, BN

*hydration upon atmospheric exposure
Table 3. Possibilities for Enhanced Local Transport of Li, Mg

A. Metal vaporization

(1) Li(i) - Li(g)

(2) 2 Li(g) + F2 (g) - 2 LiF(c)

(3) Mg(i) -* Mg(g)

(4) Mg(g) + F2 (g) - MgF2 (c)

B . Metastable formation of chloride species

(1) 2 Li (i) + Cl2 (g) - 2 LiCl(g)

(2) 2 LiCl(g) + F2 (g) - 2 LiF(c) + Cl2 (g)

(3) Mg(i) + Cl2 (g) - MgCl2 (g)

(4) MgCl2 (g) + F2 (g) - MgF2 (c) + Cl2 (g)

C . Combined mechanism

(1) Li(i) - Li(g)

(2) 2 Li (g) + Cl2 (g) - LiCl(g)

(3) 2 LiCl(g) + F2 (g) - 2 LiF(c)

(4) Mg(i) - Mg(g)

(5) Mg(g) + Cl2 (g) - MgCl2 (g)

MgCl2 (g) + F2 (g) - MgF2 ( 6 ) (c)
38

Table 4. Weight Gain of 0.3 /im Alumina as a Function of Temperature in

Flowing C103 F (nominal flow rate of 1 seem)

Temp

.

(°C)

Time

(hr)

Initial

Wt. (mg)

Wt.

Gain (mg)

% Wt.

Gain

Reaction

End

Point

% of

Theoretical

450 1.5 116.6 18.3 15.7 N 24.3

500 1.5 119.2 34.8 29.2 N 45.1

550 1.5 91.7 47.1 51.4 N 79.4

600 0.9 95.4 53.4 56.0 Y 86.5

690 1.4 94.6 55.8 59.0 Y 91.2

700 1.3 78.9 47.6 60.3 Y 93.2

750 1.3 77.3 48.7 63.0 Y 97.3

800 1.4 95.1 59.5 62.6 Y 96.7
39

Table 5. Effect of C103 F Flow Rate on Reaction with 0,.3 pm Alumina at 800°

C

Approx. Time to Initial Wt. % % of

Flow Rate Reaction Wt. Gain Wt. Theoretical

(seem) End Point

(hr)

(mg) (mg) Gain Max.

1 1.1 64.2 39.0 60.75 93.87

3 1.0 129.8 78.6 60.55 93.56

5 0.4 81.3 49.6 61.01 94.27
40

Table 6. Calculated Rate Constants for Parabolic Portion of Al2 03 /C103 F

Reaction Data

Temp

;°c)

Flow Rate

(seem)

Parabolic Rate

Constant (mg/m2 .s)

450 1 0.008

500 1 0.003

550 1 0.113

600 1 0.358

650 1 0.517

700 1 0.573

750 1 0.607

800 1 0.584

800 0.7 0.660

800 3 0.711

800 5 2.390
41

Table 7. Weight Gain of Liquid Al Droplets as a Function of Temperature in

Flowing C103 F (nominal flow rate of 1 seem)

Temp

.

(°C)

Time

(hr)

Initial Wt.

(mg)

Calc. Surface

Area

(cm2

) Wt. Gain

(mg)

Calc

.

Thickness of

Reaction Layer (yum)*

700 0.3 420.0 1.52 0.34 2

750 0.3 413.6 1.51 0.76 3

800 0.8 418.2 1.52 2.75 10

Assumes uniform coverage of AlF3.
42

Table 8. Effect of C103 F Flow Rate on Reaction with Liquid Al Droplets

at 800°

C

Approx

.

Flow Rate

(seem)

Time

(hr)

Initial Wt.

(mg)

Calc. Surface

Area Wt.

( cm2) Gain

(mg)

Calc

.

Thickness of

Reaction Layer (/im)*

0.7 0.3 411.6 1.50 1 .9 7

2.0 0.3 412.1 1.50 1 .7 6

5.0 0.2 417.9 1.52 1 .8 7 •

*Assumes uniform coverage of AlF3
43

Table 9. Calculated Rate Constants for Parabolic Portion of Al/C103 F

Reaction Data

Temp Nominal C103 F

(°C) Flow Rate (cc/min)

Parabolic Rate

Constant (mg/m2 .s)

700 1 27

750 1 155

800 1 149

800 0.7 1340

800 3 1260

800 6 2210
Table 10. Mass Spectral Ion Intensities in the System

C103 F - Al at 725°

C

Mass (/i) Species

Intensity

(microvolts)

32 02 6200

46 Air" -5

62 A1C1* 140

65 A1F2 + 50

70 cv 6600

81 A1C1F+ 110

85 SiF3 + 1500

100 A1F2 C1+ 55

116 aici2 f

+ 78

132 AlClg + 300
45

Table 11. Interactions of Chlorides and Fluorides

A. Exchange Reactions

(1) 2 Al(i) + 3 BeCl2 (g) = 3 Be(c) = 2 AlCl(g)

(2) 2 Al ( i ) + 3 BeF2 (i) = 3 Be(c) + 2 AlF3 (i)

(3) Al(2) + 3 LiCl(i) = Li(i) + AlCl3 (g)

(4) Al(i) + 3 MgCl2 (i) = 3 Li(i) + AlF3 (i)

(5) 2Al(i) + 3 MgCl2 (i) = 3 Mg(i) + 2 A1C13 (g)

(6) 2 Al (i) + 3 MgF2 (i) = 2 AlF3 (i) + Mg(i)

(7) 2 Li(i) + BeCl2 (g) = Be(c) + 2 LiCl(i)

(8) 2 Li(i) + BeF2 (c) = Be(c) + 2 LiF(i)

(9) 2 Li (2) + MgCl2 (i) = Mg(i) + 2 LiCl(i)

(10) 2 Li(i) + MgF2 (i) = Mg(i) + 2 LiF(i)

(11) Mg(i) + BeCl2 (g) = Be(c) + MgCl2 (i)

(12) Mg(i) + BeF2 (i) = Be(c) + MgF2 (i)

B . Gibbs Free Energies of Reaction (Calories')

Temperature (K)

Reaction 800 900 1000 1100 1200 1300

(1) 8,101 12,428 16,774 21,104 25,449 29,759

(2) 53,692 54,383 55,163 56 , 044 56,988 58,031

(3) 113,793 111,162 108,703 106,351 104,137 102,007

(4) 84,883 84,984 85,193 85,498 85,858 86,315

(5) 101,498 96,053 96,817 96,760 80,862 76,102

(6) 94,960 95,485 96,028 96,617 97,296 98,057

(7) -73,162 -69,965 -66,877 -63,866 60,942 58,085

(8) -40,705 -40,046 -39,556 -39,185 •38,909 38,691

(9) -42,030 -42,090 -42,196 -42,314 •42,471 •42,637

(10) -24,935 -24,828 -24,786 -24,793 •24,807 24,858

(11) -31,132 -27,875 -24,681 -21,552 •18,471 •15,448

(12) -13,756 -13,701 -13,622 -13,524 •13,436 13,342

C. Summarv of Stabilities at 1300 K (x = stable)

A1C1, AlF, BeCl, BeF, MgCl, MgF, LiCl LiF

Al X X X X X X X X

Be 0 0 X X X X X X

Mg 0 0 0 0 X X X X

Li 0 0 0 0 0 0 X X
46

Table 12. Interaction of Oxides with Fluorine or Chlorine

A. Exchange Reactions

(1) 2 A12 03 (c) + 12 F2 (g) = A1F3 (c) + 3 02 (g)

(2) 2 BeO(c) + 2 F2 (c) = BeF2 (g) + 02 (g)

(3) 2 Li2 0(c) + 2 F2 (g) = 4 LiF(i) + 02 (g)

(4) 2 MgO(c) + 2 F2 (g) = 2 MgF2 (i) + 02 (g)

(5) 2 A12 03 (c) + 6 Cl2 (g) = 4 A1C13 (g) + 3 02 (g)

(6) 2 BeO(c) + 2 Cl2 (g) = 2 BeCl2 (g) + 02 (g)

(7) 2 Li2 0(c) + 2 Cl2 (g) = 4 LiCl(i) + 02 (g)

(8) 2 MgO(c) + 2 Cl2 (g) = 2 MgCl2 (i) + 02 (g)

B. Gibbs Free Energies of Reaction (Calories')

Temperature (K)

Reaction 800 900 1000 1100 1200 1300

(1) -562,682 -553,481 -544,387 -535,387 -526,461 -517,607

(2) -132,802 -138,020 -143,180 -148,287 -153,345 -158,379

(3) -272,435 -271,964 -271,635 -271,428 -271,285 -271,230

(4) -212,096 -210,745 -209,444 -208,202 -207,077 -206,048

(5) 160,087 150,226 140,453 130,782 121,224 111,744

(6) 73,510 67,981 62,494 57,056 51,657 46,290

(7) -89,689 -90,819 -92,107 -93,476 -94,946 -96,445

(8) 4,839

C.

4,925 4,905 4,792 4,590

Summarv of Stabilities at 1300 K (x =

4,295

stable)

F Cl

Al? 0^ 0 X

BeO 0 X

MgO 0 X

Li,0 0 0
Table 13. Reaction of Chlorides with Fluorine

A. Exchange Reactions

(1) 2 AlClj (g) + 3 F2 (g) = 2 A1F3 (2) + Cl2 (g)

(2) BeCl2 (g) + F2 (g) = BeF2 (i) + Cl2 (g)

(3) 2 L1C1<2) + F2 (g) = 2 LiF(i) + Cl2 (g)

(4) MgCl2 (i) + F2 (g) = MgF2 (i) + Cl2 (g)

B. Gibbs Free Energies of Reaction ("Calories')

Temperature (K)

Reaction 800 900 1000 1100 1200 1300

( 1 ) -331,940 -324,073 -316,311 -308,633 -301,067 -293,560

( 2 ) -125,844 -122,009 -118,234 -114,525 -110,869 -107,277

(3) -91,373 -90,572 -89,764 -88,976 -88,170 -87,392

(4) -108,467 -107,835 -107,174 -106,497 -105,834 -105,172

C. Summarv of Stabilities at 1300K (0 = unstable)

F

AICI3 0

BeCl2 0

LiCl 0

MgCl2 0
Table 14. Interaction of Chlorides with Fluorides

A. Exchange Reactions

(1) 2 AlF3 (i) + 3 BeCl2 (g) = 2 A1C13 (g) + 3 BeF2 (i)

(2) A1F3 (i) + 3 LiCl(i) = AlCl3 (g) + 3 LiF(i)

(3) 2 AlF3 (i) + 3 MgCl2 (i) = 2 A1C13 (g) + 3 MgF2 (i)

(4) BeF2 (i) + 2 LiCl(i) = BeCl2 (g) + 2 LiF(i)

(5) BeF2 (i) + MgCl2 (i) - BeCl2 (g) + MgF2 (2)

(6) 2 LiF(i) + MgCl2 (i) = 2 LiCl(i) + MgF2 (2)

B. Gibbs Free Energies of Reaction ('Calories’)

Temperature (K)

Reaction 800 900 1000 1100 1200 1300

(1) -45,591 -41,955 -38,509 -34,940 -31,539 -28,272

(2) 28,910 26,178 23,509 20,852 18,279 15,692

(3) 6,538 0,568 -5,212 -10,857 -16,434 -21,955

(4) 34,471 31,437 28,469 25,548 22,699 19,885

(5) 17,376 14,174 11,059 8,028 5,035 2,106

(6) -17,094 -17,263 -17,410 -17,520 -17,664 -17,779

C. Summarv of Stabilities at 1300K <x = stable)

A1F3 BeF2 MgF2 LiF

aici3 X X X 0

BeCl2 X X 0 0

MgCl2 0 X X 0

LiCl X X X X
49

Table 15. Interaction of Oxides with Fluorides

A. Exchange Reaction

(1) A12 03 (c) + 3 BeF2 (i) = 2 AlF3 (i) + 3 BeO(c)

(2) A12 03 (c) + 6 LiF(i) = 2 AlF3 ( 2 ) + 3 Li2 0(c)

(3) A12 03 (c) + 3 MgF2 (i) = 2 A1F3 (i) + 3 MgO(c)

(4) BeO(c) + 2 LiF(i) = BeF2 (i) + Li2 0(c)

(5) BeO(c) + MgF2 (i) = BeF2 (i) + MgO(c)

(6) Li2 0(c) + MgF2 (i) = 2 LiF(i) + MgO(c)

B

.

Gibbs Free Energies of Reaction (Calories')

Temperature (K)

Reaction 800 900 1000 1100 1200 1300

(1) 15,370 15,097 14,875 14,747 14,666 14,710

(2) 156,756 158,985 161,368 163,900 166,473 169,157

(3) 66,247 67,157 68,080 69,060 70,160 71,385

(4) 47,129 47,963 48,831 49,718 50,602 51,482

(5) 16,959 17,353 17,735 18,104 18,498 18,892

(6) -30,170 -30,609 -31,096 -31,613 -32,104 -32,591

C. Summary of Stabilities at 1300K (x = stable)

A1F3 BeF2 MgF2 LiF

Al2 o3 X X X X

BeO 0 X X X

MgO 0 O X X

Li2 0 0 O 0 X
50

Table 16. Interaction of Oxides with Chlorides

A. Exchange Reactions

(1) A12 03 (c) + 3 BeCl2 (c) = 2 AlCl3 (c) + 3 BeO(c)

(2) A12 03 (c) + 6 LiCl(i) = 2 A1C13 (c) + 3 Li2 0(c)

(3) A12 03 (c) + 3 MgCl2 (i) = 2 A1C13 (c) + 3 MgO(c)

(4) BeO(c) + 2 LiCl(i) = BeCl2 (c) + Li2 0(c)

(5) BeO(c) + MgCl2 (2) = BeCl2 (c) + MgO(c)

(6) Li2 0(c) + MgCl2 (i) = 2 LiCl(2) + MgO(c)

B. Gibbs Free Energies of Reaction (Calories)

Temperature (K)

Reaction 800 900 1000 1100 1200 1300

( 1 ) -30,221 -26,858 -23,514 -20,193 -16,873 -13,562

( 2 ) 214,577 211,342 208,387 205,605 203,030 200,540

(3) 72,785 67,725 62,869 58,203 53,727 49,430

(4) 81,599 79,400 77,300 75,266 73,301 71,367

(5) 34,335 31,528 28,794 26,132 23,533 20,997

( 6 ) -47,264 -47,872 -48,506 -49,134 -49,768 -50,370

C. Summary of Stabilities at 1300K (x = stable)

AlCl3 BeCl2 MgCl2 LiCl

Al2 O3 X 0 X X

BeO X X X X

MgO 0 0 X X

Li2 0 0 0 0 X
VIII. FIGURES

Figure 1. Knudsen effusion mass spectrometric data for thermal decomposition

of C103 F.

Figure 2. Schematic of high pressure transpiration mass spectrometer cell.

Figure 3. High pressure transpiration mass spectrometer data for thermal

decomposition of C103 F.

Figure 4. Total pressure in high pressure transpiration mass spectrometer

system as a function of temperature. Break in slope indicates

beginning of C103 F decomposition.

Figure 5.

35

Ion current data for C103 + in C103 F/transpiration mass

spectrometer experiment of Figs. 3, 4.

Figure 6. Thermogravimetric curve for fluorine saturation of alumina cell by

C103 F at 800° C.

Figure 7. Thermogravimetric data for reaction of 0.3 nm alumina powder with

Clo3 F at various temperatures.

Figure 8. Thermogravimetric data for effect of C103 F flow rate on 0.3 nm

. alumina reaction at 800° C.

Figure 9. Plot of rate constants for C103 F/Al2 03 reaction data of Figs. 7 and 8.

Figure 10. Thermogravimetric data for fluorine saturation of MgO cell by

C103 F at 800° C.

Figure 11. Melted aluminum ball of type used in reaction rate studies.

Figure 12. Surface of aluminum ball after reaction with C103 F at 800° C.

Figure 13. Surface of aluminum ball after C103 F reaction, showing surface

channel under gas jet.

Figure 14. Thermogravimetric data for reaction of molten aluminum ball with

C103 F at various temperatures.

Figure 15. Thermogravimetric data for effect of C103 F flow rate on aluminum

reaction at 800° C.

Figure 16. Cooling curve for tungsten furnace used in Li2 0-Al2 03 phase

equilibrium experiments.

Figure 17. Equilibrium crystals of LiAl5 08 spinel with recrystallized

interstitial eutectic melt.

Figure 18. Phase diagram for the high alumina portion of the system

LiAl02 -Al2 03. Figure 19. lamellar intergrowths in (Li2 0)2 ^ (Al2 03 )^ ^ cooled from 1925° C.

Figure 20. DTA analysis of phase transition in LiAl*0„

.
52

Figure 25

.

Figure 26.

Figure 27.

Figure 28.

Figure 29.

Figure 30.

Figure 31.

Figure 32.

Figure 33.

Figure 34.

Figure 35.

Figure 36.

Chemical equilibria of chlorides formed by reaction with LiMgAl

alloy.

Chemical equilibria of (Mg,Al) chlorides formed by reaction with

LiMgAl alloy.

Chemical equilibria of (Li, Mg) fluorides formed by reaction with

LiMgAl alloy.

Chemical equilibria of (Li,Al) fluorides formed by reaction with

LiMgAl alloy.

Partitioning of fluorine in the lithium molten salt phase.

Partitioning of fluorine in the magnesium molten salt phase.

Vapor pressure over molten lithium and over Li + LiH mixture.

Vapor pressures over LiOH and over LiOH + Li2 0 mixture.

Partial pressures of Lithium species over their respective

condensed phases.

Partial pressures of aluminum species over their respective

condensed phases

.

Partial pressures of beryllium species over their respective

condensed phases.

Partial pressures of magnesium species over their respective

condensed phases

.
INTENSITY

(Arbitrary)

Figure 1. Knudsen effusion mass spectrometric ion intensity data for

thermal decomposition of C103 F.
BEAM

Figure 2. Schematic of high pressure transpiration mass spectrometer ceil.
10

I + Cl 2

o I"

A I + C10 3 F

V I + C10 3 + o I + C10

<] I" C10 2

r C10 3

Figure 3. High pressure transpiration mass spectrometer ion intensity data

for thermal decomposition of C103 F.
PRESSURE

(atm)

0.5

0.4

0.3

0.2

0 . 1

0

/

/

Q

/•

0 100 200 300 400 500 600 700

TEMPERATURE °C

Figure 4. Total pressure in high pressure transpiration mass spectrometer

system as a function of temperature. Break in slope indicates

beginning of C103 F decomposition.
INTENSITY

(Microvolts)

6000

5000

4000

3000

2000 -

r

r

1000

0

0 100 200 300 400 500 600 700

TEMPERATURE °C

igure 5. Ion current data for C103 + in C103 F/transpiration mass

spectrometer experiment of Figs. 3, 4.
m/

A

(mg/M*2

Figure 6. Thermo gravimetric curve for fluorine saturation of alumina cell by

C103 F at 800° C .
50

'igure 7

40

C\J 30

*

cp

< 20

<

10

0

:ijH;

:

750 0

800 C

700 C

650 C

.^-600 C

550.

0 2000 4000

o

6000

(sec)

3000 10000 12000

Thermogravimetric data for reaction of 0.3 /im alumina powder with

C103 F at various temperatures.
m/

A

(gni/M*2)

igure 8. Tnermogravimetric data for effect of C103 F flow rate on its

reaction with 0.3 alumina at 800°C.
h

(mg/M*2.*s)

io 3 /t k

Figure 9. Rate constants for CIO, F/Al,0, reaction data of

Figs. 7 and 8.
/A

(mg/M*2)

Figure 10. Thermogravimetric data for fluorine saturation of MeO T i bv

C103 F at 800° C.
Figure ii. Melted aluminum ball of type used in reaction rate studies.
Figure 12. Surface of aluminum ball after reaction with C103 r at 800°

C
Figure 13. Surface of aluminum ball after C103 F reaction, showing surface

channel under gas jet.
t (sec)

igure 14. Thermo gravimetric data for reaction of molten aluminum ball v

C103 ? at various temperatures.
ru /

A

(mg/M

)

x

10

Figure 15. Thermogravimetric data

reaction at 800°C.

tor efiect of CIO, F flow rate on aluminum
figure 16'. Cooling curve for tungsten furnace used in Li 2 0-Al 2 0 3 phase

equilibrium experiments

.
e 17. Equilibrium crystals of LiAl5 08 spinel with recrystallized

interstitial eutectic melt.
no 1 A 1 203

Figure 18. , Phase diagram for the high alumina portion of the system

LiAl02 -Ai2 0 3

.
Figure 19. Lamellar intergrowths in (L^O^ ^ ° 3 ) 97 .

5

cooled from 1925° C

.
exothernic

endothernic

-

i

1

1

i

••

/

; / - /

0

8

.. . .

e

4 —y—

1

‘

i nci

i

.... . ... 7

~eas:

i ng t

i eripei

i "a tur

f

‘C —

Figure -20. DTA analysis of phase transition in LiAl 5 08 .
1 360

1340

1320

1300

1280

1280

1240

— 1 [ r—

LiA102 + disordered 1:5

~l T

l

1

1

i

1 A 1 203 +

. | disordered

1308 ° _ * 4, +

1 l:5 —

1

1i”

L 1 A 1 02- + ordered 1 : 5

1

1

i °

1 1269

r1 A 1 203 +

« • >

1 ordered 1:5

1— 50 60 70 80 90 100

L i A 1 02 ft 1 203

moI ^ A 1203

Figure 21. Effect of composition on LiAl5 0 8 transition.
LiF AIF 3

MOL %

Figure 22. Compositions investigated in the system Li 2 0-Al2 0 3 -AiF, -LiF.
Figure 23. Effect of composition on melting at 1200°C in the system

Li2 0-Al2 03 -AlF3 -LiF. (a) composition Li 7 Al7 F6 026 shoving absence

of melt; (b) composition (LiF)^ (A12 03 ),q showing derinite

melting.
LIF (Salt Melt) AIF3

MOL %

Figure 24. Pnase relations in the system Li2 0-Al2 03 -AlF3 -LiF at 1200°C.
ion

/

2

I06

w

All

AliOV

Figure 25

.

Calculated chemical equilibria of (Li, Mg) chlorides formed

by reaction with LiMgAl alloy.

»-»
ACTIVITY

A1C1

3

/

Mg

Cl

10

10

•3

10

-24

4G0 500 500 1000 1200

Figure 26. Calculated chemical equilibria of (Mg, Al) chlorides formed

by reaction with LiMgAl alloy.
ACTIVITY

MgF

2

/

LiF

Figure 27. Calculated chemical equilibria of (Li, Mg) flourides formed

by reaction with liMgAl alloy.
ACTIVITY

AIF

a /

LiF

10

-15

I 3 LiF (1) + A 1 (1) = A1F, (!) + 3 Li (1)

i

PMPpq a

; I . . I iir“. uIRE K

Figure 28. Calculated chemical equilibria of (Li, Al) flourides formed

by reaction with LiMgAl alloy.
ACTIVITY

LiCl /

LiF

10 — —

-

/ / - / : j ?i — A C 1 2 = ^ r 2

i -

/ /

! - /

/ z

/

/ /

- /

TTTTTTp D

/

/

-

/

//

/

l

- /

i

—

/ — /

//

/

/ /

f

ir

1

i

i

i

1

1

E

/

/

1

{

i

i

1

l - rh

| 1— LiF (1) + 1/2 Cl 2 (g)

l 1

= LiCl

!

(1) 4- 1/2 F- (g) ! <— 1

! ! ! 400 600 BOO 1000 1200

1 r ; A

' ~ pj ATURE : /

r*\

i \

Figure 29. Calculated partitioning of flourine in the lithium molten

salt phase.
jGw

/bI

36

[aJ

AX

I

A1

13V

10

-19

10

-20

10

-21

10

-22

OJ -23

10

“

10

-24

10' 25

10

-26

10

-27

10

-28

10

-29

10

-30

10

-31

400 600 800 1000

TEMPERATURE K

1200

Figure 30. Calculated partitioning of flourine in the magnesium

salt phase.

mo
PRESSURE

(atm)

Figure 31. Calculated vapor pressures over molten lithium and over

Li + LiH mixture

.

a

vi
PRESSURE

(atm)

Figure 32. Calculated vapor pressures over LiOH and over a LiOH + Li 2 0 mixture.
PRESSURE

(atm)

Figure 33. Calculated partial pressures of lithium species over their

respective condensed phases.
PRESSURE

(atm)

Figure 34. Calculated partial pressures of aluminum species over the

respective condensed phases.
PRESSURE

(atm)

Figure 35. Calculated partial pressures of beryllium species over their

respective condensed phases.
PRESSURE

(atm)

Figure 36. Calculated partial pressures of magnesium species over the

respective condensed phases.
IX. DISTRIBUTION

53

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m.1 T4A iwgv. 2-4Q) U.S. DEPT. OP COMM.

BIBLIOGRAPHIC DATA

SHEET (See instructions)

1. PUBLICATION OR

REPORT NO.

NBSIR 87-3601

2. Performing Organ. Report No. 3. Publication Date JULY 1987

4. TITLE AND SUBTITLE

High Temperature Chemistry of Stored Chemical Energy Reactions for Propulsion

5. AUTHOR(S)

L. P. Cook, E. R. Plante, D. W. Bonnell , J. W. Hastie

6. PERFORMING ORGANIZATION (If joint or other than N BS, see instructions)

NATIONAL BUREAU OF STANDARDS

U.S. DEPARTMENT OF COMMERCE

GAITHERSBURG, MD 20899

7. Con tract/ Grant No.

t. Type of Report & Period Covered

9.

SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (Street. City. State, ZIP)

Office of Naval Research

800 N. Quincy Street

Arlington, VA 22217

10.

SUPPLEMENTARY NOTES

| j Document describes a computer program; SF-185, FlPS Software Summary, is attached.

11.

ABSTRACT (A 200-word or less factual summary of most significant information. If document includes a significant

bibliography or literature survey, mention it here)

This report summarizes the results of a continuing study of the high temperature chemistry of stored chemical energy reaction systems. The eight fuel /oxidant reactions of

interest (including several which are multistage) are: Li/bLO, hL/O^* NaCL/bLO, Li B/

NF

3

. Thermodynamic prediction of the products of three of these reactions nas been

corroborated by equilibrating postulated products at high temperature, while results

from a fourth reaction require modification of the reaction scheme originally proposed.

Mass spectrometric observations on the thermal decomposition of CIO^F at elevated

temperatures are presented. Thermogravimetric studies have been completed on the behavior of A1 2^3 an<* MgO in the presence of CIO^F and on the oxidation of molten aluminum

droplets by u(Lf. The solid state phase transition in Li A1 oOq has been studied by DTA.

In the CICLF-based reaction systems, substantial entry of flaorine into the product

LiAlgOg spinel phase is postulated.

Thermodynamic calculations have been completed to assess the importance of vaporization

of reactant/product solids and liquids.

12.

KEY WORDS (Six to twelve entries; alphabetical order; capitalize only proper names; and separate key words by semicolon s) A1 9CL; aluminum; kinetics; Li ? 0; lithium; magnesium; mass spectrometry; perchloryl

flaoride; phase equilibria; stored chemical energy reactions; thermal analysis;

13.

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