CERAMIC FOAM PROCESSING BY THE CHEMICAL VAPOR INFILTRATION OF A GRAPHITE FELT WITH SIC FOR CERAMIC COMPOSITE APPLICATIONS

摘要

This investigation focuses on the fabrication of fibrous silicon carbide (SiC) ceramic foams by the Chemical Vapor Infiltration (CVI) of SiC into a low cost graphite felt. Selected foams were then oxidized to produce foams consisting of hollow SiC fibers. Depending on infiltration time, densities from 0.3 to 1.0 g/cm{sup}3 were obtained (0.268 to 0.925 g/cm{sup}3 after oxidation). Compressive strength data (pre and post oxidized foams) and flexural strength data (post oxidized foams) are presented as a function of density. This unique ceramic foam with high temperature capabilities and reasonable compressive and flexural strengths was also used as a light weight core in the development of a sandwich composite structure. Coated Nicalon 4-ply laminates were used as faceplates. The composite processing included both Polymer Impregnation Pyrolysis (PIP) and the CVI of the final laminate-foam structure with a SiC overcoat. Overall composite flexural strengths are reported with respect to the bulk density of the foam core and the composite. Relatively small, 1.5 × 10 × 0.5 cm, sandwich type composites were successfully produced and possibly represent a lightweight structure for high temperature (>1000℃) applications.