Nb,Mo,Ti,Ta,W掺杂硅化石墨扫描电镜研究

以硅粉的1％，2％－10％（wB）将Nb,Mo,Ti,Ta,W等5种金属粉掺入硅粉中，用液硅渗透法（LSP）制务出系列掺杂硅化石墨样品，这对些样品抗折，抗拉强测试结果：Nb(6%)－硅化石墨性能最优，抗拉强度提高了20％－27％，Mo(1%),Mo(5%)掺杂效果次之，而Ti(7%),Ta(3%),W(7%)等的杂反使材料强度降低。扫描电子显微镜（SEM）分析显示：Nb(6%）掺杂使抗担强增强的原因在于，新的铌与碳的间隙化合物相的生成，减小了硅化石墨显微结构的尺寸，且使材料外层及内核结构均匀，致密，统一，因而能有效分散应力集中，缓冲裂纹扩张，增大承载截面，从而提高材料力学性能。相反Ti(7%),Ta(3%)等掺杂后，尽管使材料外层结构致密，但内部结构疏松，晶粒，孔隙尺寸不大小不一，形态各异，外结构极不统一，导致材料性能下降。

STUDY ON SCANNING ELECTRON MICROSCOPE OF Nb,Mo,Ti,Ta,W DOPING SILIC ATED GRAPHITE

When 1%,2%-10%silicon powdering and five metals of Nb,Mo,Ti,Ta,W were added to silicon powder,a series of doping silicated graphite sample were prepared by LSP.The result of anti bending and anti tensile strength test of samples showed:Nb(6%) silicated graphite property is the best of all,with its tensile strength increasing 20%-27%;effect of doping of Mo(1%),Mo(5%) takes the second place.But doping of Ti(7%),Ta(3%) and W(7%),in contrast,seems reduce the material intension.The analysis of SEM shows that Nb(6%) doping enhancement is attributed to the formation of the new clearance compound phase of Nb and C.This formation diminishes the silicated graphite microstructure size,which leads to the uniformity and compactedness of the outer layer and kernel structures.This can effectively disperse stress concentration,buffer creackle expandsion,increase bear ability of the weight of section and accordingly enhance material mechanics property.In the opposition,Ti (7%),Ta(3%) and other doping silicated graphite leads material outer layer structure to compactedness,but inner structure to looseness,different crystal and hole size,configuration diversifying,and inner and outer structure to disunity.Hence,it destroys material property.