Accession Number : AD0888888

Title :   Transition Metal Diboride Matrix Composites.

Descriptive Note : Final technical rept. 1 Jun 69-30 Nov 70,

Corporate Author : UNION CARBIDE CORP PARMA OH CARBON PRODUCTS DIV

Personal Author(s) : Schulz, D. A. ; Volk, H. F.

Report Date : APR 1971

Pagination or Media Count : 117

Abstract : Titanium diboride and zirconium diboride composites containing 'Thornel' 50 graphite fibers, silicon carbide whiskers, and 'Zircar' zirconium oxide fibers were fabricated by hot-pressing. In all composites fabricated to near theoretical density, degradation of the fibrous component occurred. The degradation is a recrystallization process, rather than a chemical interaction between the fibers and the matrix components. Recrystallization took place in each of the types of fibers, including 'Thornel' 50 fibers coated with TiC and TiB2. In diboride composites containing SiC whiskers, the recrystallization of the whiskers was greatly reduced by using large diameter (>5 micrometers) whiskers. The strength of composites containing the undegraded SiC whiskers, however, was less than that of the unreinforced diboride matrix. The strongest zirconium diboride composites were fabricated with 'Zircar' stabilized zirconia fibers. The average strength of the strongest 'Zircar' - ZrB2 composite was 81,000 psi. The composition of the strongest composite was 64 volume percent ZrB2 powder, 16 volume percent SiC powder, and 20 volume percent 'Zircar' ZrO2 fibers. (Author)

Descriptors :   *CERAMIC FIBERS), (*COMPOSITE MATERIALS, (*BORIDES, COMPOSITE MATERIALS), TITANIUM COMPOUNDS, ZIRCONIUM COMPOUNDS, CARBON FIBERS, SILICON CARBIDES, HOT PRESSING, OXIDES.

Subject Categories : Laminates and Composite Materials

Distribution Statement : APPROVED FOR PUBLIC RELEASE