(合肥工業(yè)大學(xué) 材料學(xué)院，合肥 230009)
摘 要: 以微米級(jí)的碳化硅粉和石墨粉為原料，采用氧化結(jié)合法制備出不同孔隙含量的、適合液態(tài)鋁無(wú)壓滲透的SiC預(yù)成形坯。研究SiC多孔陶瓷的低溫?zé)Y(jié)機(jī)理和石墨添加量對(duì)SiC陶瓷骨架燒結(jié)密度和尺寸變化的影響。結(jié)果表明：在1 100 ℃燒結(jié)時(shí)，碳化硅和石墨粉同時(shí)發(fā)生氧化反應(yīng)；SiC氧化產(chǎn)生的結(jié)晶態(tài)SiO2膜將SiC粉體粘結(jié)成陶瓷骨架，石墨氧化去除后形成孔隙；SiC粉體間本征孔隙和石墨去除后留下的孔隙構(gòu)成三維互連通狀態(tài)；因SiC氧化導(dǎo)致陶瓷骨架產(chǎn)生4%左右的線(xiàn)膨脹，但坯體不發(fā)生形狀改變；通過(guò)調(diào)整石墨含量，能獲得孔隙率從0.47~0.63的SiC陶瓷骨架。
關(guān)鍵字: SiC預(yù)成形坯；氧化結(jié)合；孔隙率；造孔劑；線(xiàn)膨脹
（School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009, China）
Abstract:Abstract: SiC preforms with different porosities for Al pressureless infiltrating in were prepared by oxidation bonding process deriving from micron-grade powders of SiC and graphite. The low temperature sintering mechanism of SiC preforms and the effect of graphite content on the density and dimension of the porous preforms were studied. The results show that SiC powders and graphite powders oxidize synchronously at 1 100 ℃ in air atmosphere; Crystalloid SiO2 film transformed from SiC by oxidation bonds SiC powders to each other to form a ceramic skeleton, and the sites occupied by graphite powders turn into pores when graphite powders burned out. Three dimensional co-continuous net-work of pores is achieved by original clearance among SiC powders and pores formed by graphite powders. The linear expansion of SiC preforms without any deformation is about 4% due to oxidation of SiC powders. SiC preforms with porosity ranging from 0.47 to 0.63 can be obtained by modulating graphite content.
Key words: SiC preforms; oxidation bonding; porosity; pore-forming agent; linear expansion
