复杂形状碳化硅陶瓷构件制备新工艺研究

Study on Novel Procedure for Complex-shaped SiC Ceramic Components

用光固化快速成形技术制作复杂构件的负模,以酚醛树脂和淀粉的混合物填充负模,固化后在800℃高温下热解制成构件的碳支架,碳支架在真空炉中渗硅生成含有SiC/C/Si的陶瓷复合材料构件。统计分析了构件的收缩变形;用SEM及光学显微镜分析了制件的微观结构;研究了渗硅温度对材料抗弯强度的影响。结果表明:制件在各个方向的尺寸收缩率一致,大约为17%;碳支架含有由微孔和孔道组成的孔系,显气孔率越高,越利于渗硅反应;制件的抗弯强度随渗硅温度的升高而降低。应用该工艺制作了叶轮和叶片样件,所获制件形状和表面质量良好。

A negative mold for complex-shaped component was fabricated by stereolithography technology, and then the mold was filled with mixture of phenolic resin and starch. After solidified, the sample was pyrolyzed at 800℃ to be a carbon template that was transformed to be SiC component by reactive infiltration of Si. The sample shrinking and distortion was analyzed through statistical comparison. The microstructures of the ceramic components and carbon template were observed with scanning electron microscope and optic microscope. The effect of the reactive temperature on three point bending strength was also studied. The results show that the shrinkage of the sample at all dimensional directional is the same and it is about 17%. Small pores and channels form the pores system in the carbon template. The higher the open porosity of the carbon template, the better the reactive infiltration of Si. The bending strength of the sample decreases with the increase of reactive temperature. Finally, a vane sample and a impeller sample were fabricated using this procedure, the shape and the surface final quality of the sample are sufficient.