Accession Number : ADA255047

Title :   Compatibility of Refractory Metal Boride/Oxide Composites at Ultra-High Temperatures.

Descriptive Note : Final rept. Sep 87-Mar 90,

Corporate Author : TEXAS UNIV AT EL PASO DEPT OF METALLURGICAL AND MATERIALS ENGINEERING

Personal Author(s) : Bronson, Arturo ; Ma, Yu-Tao ; Mutso, Rein R.

Report Date : DEC 1990

Pagination or Media Count : 65

Abstract : The compatibility of the HfO2/HfSi2/HfB2 phases has been investigated in an argon atmosphere at 1800 deg, 1700 deg and 1600 deg C. At the three temperatures investigated, HfB 2 was determined to be relatively inert to either the oxide or silicide phases when examined with the scanning electron microscope and optical microscope. At 1800 deg C, a reactive product was found between the hafnia and hafnium dislicide phases with a wavy interface moving, parabolically with respect to time. The microstructural analysis of the interface suggests that liquid contributes to the interfacial reactions. In addition, two-solid phases (Hf 2 Si and HfSi) were formed at temperature along with silicide and silicate liquids located between HfSi2 and HfO2. At 1600 deg C for annealing times from 4 to 50 hours, the HfSi 2 /HfO 2 interface does not react as inferred from the acquired constant thickness of the silicide layer. Ceramic Composites, High Temperatures Materials Boride-Oxide Composites, Compatibility, Silicide-Oxide Composites.

Descriptors :   *BORIDES, ADDITION, ANNEALING, ARGON, ATMOSPHERES, COMPATIBILITY, CONSTANTS, ELECTRON MICROSCOPES, ELECTRONS, HAFNIUM, HIGH TEMPERATURE, INTERFACES, LAYERS, LIQUIDS, MICROSCOPES, OXIDES, SCANNING, SCANNING ELECTRON MICROSCOPES, SILICATES, SILICIDES, SILICON, SOLID PHASES, TEMPERATURE, THICKNESS, COMPOSITE MATERIALS.

Subject Categories : Laminates and Composite Materials

Distribution Statement : APPROVED FOR PUBLIC RELEASE