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):

Report Date:

1964-07-01

Pagination or Media Count:

137.0

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 MoSi2Mo and WSi2W 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

Subject Categories:

Distribution Statement:

APPROVED FOR PUBLIC RELEASE