SiCp/Al复合材料的自发熔渗机理

以Mg为助渗剂,采用液态铝自发熔渗经氧化处理的SiC粉体压坯的方法,制备出高增强体含量的SiCp/Al复合材料.通过考察铝液在SiC粉体压坯中的渗入高度与温度、时间的关系来研究铝液的熔渗机理,并对SiCp/Al复合材料进行X射线衍射、能量散射谱和金相分析.结果表明:在熔渗前沿发生的液-固界面化学反应促进两相润湿,毛细管力导致铝液自发渗入到SiC多孔陶瓷中;熔渗高度与时间呈抛物线关系.熔渗激活能为166 kJ/mol,这表明渗透过程受界面反应控制.经氧化处理的SiC粉体均匀地分布在金属基体中,其轮廓清晰.在SiCp/Al复合材料中未发现Al4C3的存在.

SPONTANEOUS INFILTRATION MECHANISM FOR SiCp/Al COMPOSITES

SiCp/Al composites with high SiC content were prepared by spontaneous infiltration of liquid aluminum into oxidized SiC powder compact enhanced by adding magnesium. The infiltration mechanism was studied by inspecting the infiltration height of liquid aluminum in the pressed block of SiC powder versus temperature and time in the course of infiltration. SiCp/Al composites were analyzed by X-ray diffraction, energy dispersive spectroscopy and metallographic analysis. The results show that the liquid-solid interface reaction at the infiltration front enhances the wettability of the system, which leads to spontaneous infiltrating of liquid aluminum into the porous SiC powder bed. The infiltration height increases parabolically with time. The activation energy for infiltration is about 166 kJ/mol, which suggests that the infiltration procedure is controlled by an interface reaction. The oxidized SiC particles are distributed uniformly with clean boundaries in the metal matrix and no Al4C3 present in the composites.