RESEARCH AND DEVELOPMENT OF REFRACTORY OXIDATION RESISTANT DIBORIDES
Abstract
The oxidation, mechanical and physical properties of zirconium diboride and hafnium diboride and composites prepared from these diborides with appropriate additives, have been determined as a function of composition, microstructure and test temperature. The composites were designed to enhance oxidation resistance, strength and thermal stress resistance without sacrificing high temperature stability; the principal additives were silicon carbide or graphite. Several hundred diboride billets, in sizes from two inches diameter to six inches square, were fabricated by conventional hot pressing. A unique role for ceramic additives has evolved in enhancing the fabricability of diboride materials and producing fine grained crack free billets. All power materials and hot pressed microstructures subjected to properties evaluations have undergone extensive characterization through qualitative and quantitative chemical analyses, phase analyses and grain size and density measurements. An exploratory fabrication effort was initiated to develop alternate means to hot pressing for producing dense diboride materials; hot forging, plasma spraying and sintering are being studied. In addition, the hot pressing of diboride compositions containing additives such as SiC whiskers, carbon filaments or tungsten filaments is being studied.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1968
- Accession Number
- AD0839956
Entities
People
- David Kalish
- Edward T. Peters
- Edward V. Clougherty