Qian Junmin,Jin Zhihao
(School of Material Science and Engineering,Xi'an Jiaotong University,Xi'an 710049,China)
Abstract:Porous SiC ceramic was prepared by the reactive infiltration of liquid Si into woodceramics made from basswood powder impregnated with phenolic resin by carbonizing at 800 and 1600 ¡ãC for 4 h.Scanning electron microscopy and X-ray diffraction were employed to characterize and analyze the microstructures and phase identification of woodceramics and porous SiC ceramic,respectively.Fourier transform infrared spectrometer was applied to analyze the physico-chemical structural changes of woodceramics.The Archimedes and three-point bending methods were used to test the apparent porosity and bending strength of woodceramics and porous SiC-ceramic,respectively.The results show that woodceramics are porous non-graphitizable carbonaceous meterials containing C£O£C£¬C = C bonds and C£H structure.The resulting porous SiC ceramic is composed of major crystal phase ¦Â-SiC and secondary phase residual free Si.The microstructure of woodceramics is inherited in porous SiC ceramic.The conversion of woodceramics into porous SiC ceramic significantly improves the bending strength from 12.6 MPa to 73.8 MPa,and decreases the apparent porosity from 64.1% to 53.2%£®
Keywords:woodceramics;porous ceramics;silicon carbide;reactive infiltration