EQUILIBRIUM STUDIES OF REFRACTORY NITRIDES. PART II. WORK ON BN, SI3N4 AND THE TA-N SYSTEM.
Summary technical rept. 1 Aug 65-31 Jul 66,
LITTLE (ARTHUR D) INC CAMBRIDGE MA
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This report presents vaporization studies on BN, Si3N4 and the Ta-N system utilizing an equilibrium technique. The apparatus assembled for these refractory nitride studies was described previously in Part I of AFML-TR-65-299. The equilibrium nitrogen pressures obtained for BN over a temperature range of 1898-2146 K are within a factor of two of those reported previously by workers using a dynamic measurement technique. Thus the results substantiate our understanding of the vaporization behavior of this compound. Work on Si3N4 was limited to one temperature because of experimental difficulties caused by the volatility of silicon. We did, however, obtain data which supports the results of previous workers. Studies on the Ta-N system are considered incomplete they only include measurements on compositions up to about 30 atom percent nitrogen which is barely into the Ta2N phase region. Our data substantiate and extend previous work in the metal solution phase region the limited data obtained for the Ta2N phase region indicates the possibility of error in previously reported studies. Data for the Ti-N system which were originally presented in Part I of AFML-TR-65-299 are revised to correct for an error in our pyrometer calibration curve. Predictions from simple solution theory are compared with experiment and discussed. Author
- Physical Chemistry
- Miscellaneous Materials