Accession Number : AD0609167

Title :   INVESTIGATION OF MECHANISMS FOR OXIDATION PROTECTION AND FAILURE OF INTERMETALLIC COATINGS FOR REFRACTORY METALS.

Descriptive Note : Summary rept. no. 2, 1 Jul 63-1 Jul 64,

Corporate Author : PHILCO RESEARCH LABS NEWPORT BEACH CALIF

Personal Author(s) : Bartlett,R. W. ; Gage,P. R.

Report Date : JUL 1964

Pagination or Media Count : 137

Abstract : An investigation of the oxidation behaviour and related characteristics of bulk silicides and silicide coatings of molybdenum and tungsten was conducted. The study included (a) the growth kinetics of disilicide coatings, (b) marker experiments to identify diffusing species during disilicide coating formation, (c) a thermochemical analysis of halide enhanced silicon vapor transport during coating processing, (d) the growth rates of intermediate silicides in the MoSi2/Mo and WSi2/W systems using an electron microprobe technique, (e) the microstructure of protective oxide films grown on MoSi2 and the nonprotective oxidation products formed at low temperatures, (f) an analysis of the oxidation process and the resultant chemistry of the oxidation products based on thermochemical and diffusion rate data, (g) an experimental and analytical treatment of oxidation of molybdenum silicides at high temperatures, to 1600C, and reduced oxygen pressures, and (h) a correlation of experimental coating failure times, in normal oxygen atmospheres, with the required time to transform primary disilicide coatings to lower nonprotective silicide phases. (Author)

Descriptors :   (*REFRACTORY COATINGS, SILICIDES), (*SILICIDES, INTERMETALLIC COMPOUNDS), (*INTERMETALLIC COMPOUNDS, OXIDATION), FILMS, PROTECTIVE COVERINGS, REFRACTORY METALS, MOLYBDENUM COMPOUNDS, TUNGSTEN COMPOUNDS, OXIDES, PHASE STUDIES, REACTION KINETICS, THERMOCHEMISTRY, HALIDES, TRANSPORT PROPERTIES, VAPORS, DIFFUSION, MICROSTRUCTURE

Distribution Statement : APPROVED FOR PUBLIC RELEASE