PRESSURE-PULSED CHEMICAL VAPOUR INFILTRATION OF SIC INTO TWO-DIMENSIONAL-TYRANNO/SIC PARTICULATE PREFORMS FROM SICL4-CH4-H-2

摘要

SiC was infiltrated in two-dimensionally woven Tyranno/SiC particulate preforms from SiCl4-CH4-H-2 using pressure-pulsed chemical vapour infiltration (PCVI) in the temperature range 1348-1423 K. Above 1373 K, only beta-SiC was deposited, whereas, at 1348 K, Si codeposition was found. At 1423 K, a macrosurface film was formed in the early stage of PCVI. At 1373 K, residual porosity decreased from 30% to 7.5% irrespective of the sample size. Three point flexural strength increased with decreasing residual porosity and increasing fibre volume fraction in the sample. Flexural strength of the sample having 48% fibre volume fraction reached about 325 MPa after 5 x 10(4) pulses of CVI at 1373 K. Inter-laminar shear strength of the sample obtained at 1373 K reached 40 MPa at 7 x 10(4) pulses. [References: 14]