(東北大學 材料各向異性與織構(gòu)教育部重點實驗室，沈陽 110004)
摘 要: 以磷片石墨Cfg，SiC，B4C和TiO2為原料，熱壓合成C-SiC-B4C-TiB2復(fù)合材料，研究不同Cfg含量和熱壓溫度對復(fù)合材料顯微組織和力學性能的影響規(guī)律。結(jié)果表明：燒結(jié)過程中TiO2與B4C反應(yīng)原位生成TiB2；復(fù)合材料的密度和抗彎強度隨著熱壓溫度的升高而增加，卻隨著Cfg含量的增加而降低，隨著熱壓溫度的升高和Cfg含量的增加，復(fù)合材料的斷裂韌性則提高；在2 000 ℃，25 MPa下熱壓時，Cfg含量為20%(質(zhì)量分數(shù))的復(fù)合材料其體積密度為2.81 g/cm3，抗彎強度為236.7 MPa，斷裂韌性為5.3 MPa∙m1/2，Cfg含量為65%含量的復(fù)合材料的體積密度為2.42 g/cm3、抗彎強度為103.6 MPa、斷裂韌性為8.1 MPa∙m1/2；復(fù)合材料的致密化程度和陶瓷晶粒隨熱壓溫度的升高而增大，復(fù)合材料中Cfg層狀分布結(jié)構(gòu)隨Cfg含量的增加更加明顯；復(fù)合材料中Cfg弱界面分層誘導(dǎo)韌化作用及第二相TiB2和陶瓷基體熱膨脹系數(shù)不匹配所產(chǎn)生的殘余應(yīng)力導(dǎo)致的裂紋偏轉(zhuǎn)作用是復(fù)合材料斷裂韌性提高的主要原因。
關(guān)鍵字: C-SiC-B4C-TiB2復(fù)合材料；熱壓；顯微組織；力學性能
（Key Laboratory for Anisotropy and Texture of Materials, Ministry of Education, Northeastern University, Shenyang 110004, China）
Abstract: C-SiC-B4C-TiB2 composites were prepared with raw materials such as flake graphite Cfg, SiC, B4C and TiO2 by in situ synthesis and hot pressed. The effects of Cfg content, sintering temperatures on the microscope structure and mechanical properties of composites were studied. The results show that TiB2 particles form by the reaction of TiO2 and B4C in the composite in the sintering process. The density and flexure strength increase with increasing sintering temperature, while decrease with increasing Cfg content. The fracture toughness increases with increasing sintering temperature and Cfg content. The density, flexure strength and fracture toughness of the composite is 2.81 g/cm3, 236.7 MPa, 5.3 MPa∙m1/2 with 20%Cfg(mass fraction) at 2 000 ℃ and 25 MPa, as well as 2.42 g/cm3, 103.6 MPa, 8.1 MPa∙m1/2 with 65% Cfg at 2 000 ℃ and 25 MPa. The pyknosis degree increases and the ceramic crystal grains of the composites grow up with increasing sintering temperature, Cfg layers structure of the composites become clearly with increasing Cfg content. It is found that the toughning mechanism of the composites is mainly that the lamination between Cfg and ceramic phase, which results in the toughening effect induced by the lamination of weak crystal boundary, and the thermal stress due to the heat expansion mismatching between ceramic phase and the second phase TiB2 leads to the heat stress micro crack deflection in the composites.
Key words: C-SiC-B4C-TiB2 composite; hot pressed; microstructure; mechanical property
