铌掺杂对硅化石墨的增强效应

按硅粉的1％，5％，6％，10％将铌粉加入硅粉中，用“液硅渗透法”制备出四种掺铌硅化石墨样品。力学性能测试结果表明：6％铌掺杂增强效果最好，可使硅化石墨抗折、抗拉强度达178．5MPa,94.2%MPa,XRD、SEM、EPMA测试分析表明铌掺杂增强硅化石墨的机理是：碳化铌相的生成使原材料平直表面界面锯齿化，并平衡晶界附近不饱和价键，降低了晶界能；同时掺杂行为使晶粒细化，晶粒尺寸减小、气孔均匀分布，从而减弱应力集中，抑制裂纹扩展，提高材料强度。铌掺杂硅化石墨是改善材料性能的有效方式。

REINFORCING EFFECT OF Nb DOPING SILICIFIED GRAPHITE

Four samples of Nb doping silicified graphite were prepared by Liquid Silicon Penetration as 1%, 5%, 6%, 10% percent mass of Nb was added to Si powder. The measured mechanical properties indicate that the reinforcing effect of 6% Nb doping silicified graphite is the best in the four samples. Its bending and tensile strength amounts to 178.5 MPa and 94.42 MPa. The mechanism of intensifying of silicified graphite via Nb doping was based on the XRD, SEM and EPMA analyses. Formation of NbC phase caused straight surface grain boundary structure to form sawtooth and balance non-saturation bonds of grain boundary and reduce grain boundary energy. Nb doping also makes grains become tiny and reduces grain size, makes stress concentrate and limits the spread of crackles and makes homogeneous distribution of gas holes. Thus material straight is enhanced. Therefore, Nb doping silicified graphite is a practical way to improve material properties.