Accession Number : ADA114834

Title :   Process Development for Silicon Carbide Based Structural Ceramics.

Descriptive Note : Interim rept. 1 Jan-31 Aug 81,

Corporate Author : MICHIGAN UNIV ANN ARBOR DEPT OF MATERIALS AND METALLURGICAL ENGINEERING

Personal Author(s) : Hucke,Edward E

PDF Url : ADA114834

Report Date : Feb 1982

Pagination or Media Count : 65

Abstract : The objective of this program is to develop a process for making shaped silicon carbide based ceramic materials with reduced microstructural flaw size by in situ reaction of silicon with fine, ultra-uniform pored carbon skeletons that are produced from liquid polymer solutions without particulate additions. Subsidiary objectives are: (1) delineation of the maximum section size producible while maintaining microstructural uniformity; (2) production of microstructures with characteristic features reduced from the current level of approximately 5-10 microns to the level of 1 micron or less; (3) characterization of microstructure, corresponding strength levels, and statistical uniformity; and (4) delineation of dimensional tolerances and surface finish that can be held during processing without finished machining. Very uniform and reproducible carbon skeletons have been produced and modified to provide for easy siliconization without extensive grain coarsening or formation of silicon veins and/or lakes have been achieved from 1 cm thick samples of carbon skeleton with particle size of 3.2 microns and pore size of 1.9 micrometers. The siliconized material has a maximum grain size of 10 micrometers and a Weibull characteristic four point bend strength of 660 mPa, which significantly exceeds other reaction bonded silicon carbide materials and compares favorably with hot pressed SiC (NC203) tested under similar circumstances.

Descriptors :   *Ceramic materials, *Silicon carbides, *Industrial production, *Processing, Structural properties, Microstructure, Defects(Materials), Carbon fibers, Porous materials, Skeleton, Grain size, High strength, Polymers, Solutions(Mixtures), Toughness, Fracture(Mechanics), Thermal stresses, Surface finishing, Powders, Thermal properties, Tolerance, Machining

Subject Categories : Ceramics, Refractories and Glass
      Refractory Fibers

Distribution Statement : APPROVED FOR PUBLIC RELEASE