材料期刊网

为了揭示脱脂预氧化对粉末注射成形碳化硅显微组织的影响规律,制定最佳热脱脂工艺,采用空气热脱脂方法对碳化硅制品进行了脱脂（550～950℃）.结果表明：随预氧化温度升高烧结制品气孔率先降低后增加,650℃预氧化脱脂坯烧结后气孔率最低;预氧化可以有效促进脱脂坯烧结收缩,但过高的预氧化温度易引起失重增加,650℃预氧化脱脂坯烧结后具有最高的真实密度（3.20 g/cm3）,高于未经预氧化直接烧结制品（3.18 g/cm3）;烧结后试样由固相碳化硅与晶间液相组成,XRD及TEM能谱分析表明试样内部无残余氧化硅;随预氧化温度的升高烧结试样液相逐渐减少,液相的减少影响了氧化铝与氧化钇的比率,因此烧结试样未见明显YAG衍射峰出现;晶间液相阻碍了碳化硅晶粒间的扩散长大,制品晶粒平均尺寸小于1μm.空气热脱脂可取代传统气氛保护热脱脂,预氧化温度应控制在550～750℃.

To investigate the effect of pre-oxidation on the microstructure of powder injection molded SiC,the moded green parts were debound in air furnace.Firstly,the porosity of sintered samples decreases with the pre-oxidation temperature increase from 550 ℃ to 650 ℃,and then increases from 650 ℃ to 950 ℃.The measured density of sintered sample with pre-oxidation at 650 is the largest（3.20 g/cm3） among all samples with or without pre-oxidation.Sintered samples contain SiC phase and intergranular liquid phase.There is no SiO2 in all sintered samples base on the analysis of XRD and TEM.The loss intergranular liquid phase affects the formation of YAG（Y3Al5O12）.So,no diffraction peak of YAG is found in the test results by XRD.The average grain size of sintered samples is less than 1 μm.Test results indicate that,thermal debinding could be conformed in air instead of inert gas shield under 550~750 ℃.