The effect of porous carbon preform and the infiltration process on the properties of reaction-formed SiC

The effect of porous carbon preform and the infiltration process on the properties of reaction-formed SiC have been investigated in this paper. Five different porous carbon preforms with porosity in a range 35-67% and pore size from 0.03 to 2.58 mum have been infiltrated with liquid or vapor Si. The porous carbon preform and infiltration process affect the reaction rate and infiltration rate, which are key issues in designing the final reaction-formed silicon carbide microstructure. Under suitable experimental conditions, vapor infiltration can lead to deeper infiltration of Si than liquid infiltration. The best result has been obtained by vapor Si infiltration with a relatively smaller scale porous carbon preform having a density of 0.92 g cm(-3). The reaction-formed silicon carbide with a flexural strength 630 MPa and density 3.12 g cm(-3) and Si-content 8 vol.%, which is superior to commercially obtained reaction-bonded silicon carbides, have been fabricated by Si vapor infiltration. (C) 2004 Elsevier Ltd. All rights reserved.