REFRACTORY MATERIALS RESEARCH. Ninth Quarterly Progress Report, October 1, 1962 to December 31, 1962

Concurrently with the design and fabrication of apparatus modifications to be used in studying evaporation of borides, an additional series of measurements of the rate of N/sub 2/ effusion from a Knudsen cell containing HfN was made, and two additional series of measurements in the Ta-N high N/sub 2/ content region were also completed. The HfN results provide further evidence that the orifice effects noticed are related to diffusion limitations rather than to a non-unit evaporation coefficient. Nitrogen pressures computed from effusion rates from Ta--N compositions were found to differ widely from one series to another in the region of 33 to 48 at.% N/sub 2/. No satisfactory explanation can be given, at present, for this behavior. In matrix isolation studies of the infrared spectra of vapor species over ZrO/sub 2/, spectra were obtained in solid Ar matrices, and several fundamentai frequencies of ZrO/sub 2/ and ZrO molecules were identified. Resonance line absorption measurements of both the B and Zr atom lines in the vapor over pure ZrB/sub 2/ were made and absorption measurements over the pure elements are now proceeding. The normal spectral emissivities of TaN and of pyrolytic graphite at 1600 to 2400 deg K were measured andmore » normal total emissivities were computed. (auth)« less