陶瓷微结构件的注射成形工艺及其微观组织

Injection Molding Process and Microstructure of Ceramic Micro-Structured Part

采用粉末微注射成形技术制作了ZrO2陶瓷微结构件,分析了其注射成形工艺,包括喂料配制、注射工艺及烧结工艺对微观组织的影响.实验结果表明,粉末体积分数为55%的生坯注射成形后在1 500℃下烧结2 h,采用排水法测得其微结构相对密度高达98.5%,采用纳米硬度分析法得到其微结构的显微硬度值为13.75 GPa.扫描电子显微镜(SEM)结果表明,提高模具温度和注射压力,有利于微结构的填充,进而改善微结构件的微观组织;高的烧结温度可以增加零件的致密度,但容易导致晶粒的过度长大和尺寸不均匀.激光共聚焦光学显微镜观察结果表明,使用亚微米级陶瓷超细粉得到的微结构具有良好的表面质量,其烧结前、后的表面粗糙度值分别为0.33μm和0.28μm.此外,提高粉末含量可以减小零件收缩率,从而有利于微结构的尺寸精度控制.

ZrO2 micro-structured parts were fabricated with powder micro injection molding process.The forming process of ceramic micro-structured part,such as feedstock preparation,injection parameters and sinter process and the effect of these parameters on the microstructure was analyzed.Experimental results indicate that the relative density and microhardness of the micro-structured part sintered under 1 500 ℃ for 2 h are 98.5% and 13.75 GPa,respectively.Observation results of scanning electron microscope（SEM） reveal that higher mold temperature and injection pressure contribute to the improvement of filling performance and microstructure.Increasing sintering temperature can induce the densification of micro-structured part,while resulting in the overgrowth and non-homogeneity of grain.Good surface roughness of sintered ceramic micro-structured parts can be obtained by using sub-micron ZrO2 powder.Observation results of confocal laser scanning microscope reveal that the surface roughnesses of green and ceramic micro-structured parts are 0.33 μm and 0.28 μm,respectively.Moreover,the shrinkage of micro-structured parts decreases with the increase of powder content in feedstock,which is favorable to precise control of the micro-structured parts.