Accession Number : ADA304272

Title :   Synthesis of Net-Shape Ceramic Matrix Composites from Phase Separated Polymeric Precursors.

Descriptive Note : Annual technical rept. 1 Feb 95-31 Jan 96,

Corporate Author : MASSACHUSETTS INST OF TECH CAMBRIDGE

Personal Author(s) : Haggerty, John S. ; Seyferth, Dietmar

PDF Url : ADA304272

Report Date : 01 FEB 1996

Pagination or Media Count : 6

Abstract : This program seeks means of fabricating thick cross-section monolithic and composite ceramic components using polymeric ceramic precursors, thereby realizing potential processing and quality advantages. This program's strategy for overcoming longstanding problems is based on developing and maintaining a precisely controlled interconnected pore structure within the reacting part, thus providing a pathway through which gaseous reaction products can escape without damaging the part and into which gaseous reactants can freely penetrate, enabling synthesis reactions to proceed uniformly at maximum rates. The approach taken is based on filling the void space within solid phase reactants because this option offers important opportunities for minimizing both shrinkage and residual porosity. During the past year this research has: (1) investigated whether inert fillers can be made to act as nuclei for reaction products formed from the polymeric ceramic precursors, (2) sought means to prevent migration of the reactive binders during drying, and (3) made reaction formed silicon nitride matrix composite parts using mullite fibers. Results indicate that the approach is viable. (MM)

Descriptors :   *POLYMERS, *CERAMIC MATRIX COMPOSITES, *CERAMIC MATERIALS, FIBER REINFORCED COMPOSITES, X RAY DIFFRACTION, CRYSTALLIZATION, POROSITY, INERT MATERIALS, BINDERS, REACTANTS(CHEMISTRY), DRYING, SILICON NITRIDES, SOLID PHASES, FILLERS, SHRINKAGE.

Subject Categories : Ceramics, Refractories and Glass
      Laminates and Composite Materials

Distribution Statement : APPROVED FOR PUBLIC RELEASE