添加氧化铝烧结助剂的碳化硼陶瓷无压烧结工艺研究

采用无压烧结工艺,通过添加质量分数为5%的氧化铝烧结助剂,制备得到了碳化硼陶瓷,其中烧结温度从2000℃到2250℃,保温时间为1、2和3 h。对烧结试样进行了体积密度、显气孔率、维氏硬度、显微形貌和晶体结构测试,并与2250℃下烧结得到的不添加烧结助剂碳化硼试样进行了比较。实验结果表明:由于烧结助剂与碳化硼在扩散运动中的相互作用,导致添加氧化铝助剂无压烧结碳化硼晶粒的形态变化具有温度选择性;氧化铝助剂所体现的液相扩散作用和钉扎作用,既可阻碍碳化硼晶粒长大,又可大幅度降低碳化硼的气孔率;通过烧结工艺控制氧化铝助剂成分在晶粒烧结体中的比例,可以将氧化铝成分完全包裹在碳化硼晶粒内部,有利于碳化硼烧结中的晶粒控制和空隙调整,从而避免助剂成分对烧结碳化硼可能造成的不利影响。

Pressureless sintering of boron carbide with an addition of alumina

Theboron carbide ceramics doped by 5％ alumina by mass as sintering additive were sintered by pressureless sintering at the temperature range from 2000℃ to 2250℃ in the sintering time range from 1 h to 3 h. The volume density, open porosity, micro-hardness, surface morphology, and crystal structure of sintering samples with and without alumina sintering additive were investigated. In the results, the alumina doped as sintering additive can provide liquid phase diffusion powerand pinning effect for sintering, block the abnormal growth of boron carbide grains, significantly reduce the porosity of boron carbide, and even go into the boron carbide particles. It can be used to control the crystal particles and microstructures of boron carbide.