AlN/YAlO_(3)复合陶瓷的抗热震性能

Thermal Shock Resistance of AlN/YAlO_(3) Composite Ceramics

AlN陶瓷硬度高、脆性大,难以烧结致密,作为熔炼容器时会因高温变形或被温度变化引起热冲击破坏。将YAlO_(3)作为颗粒增强相加入AlN中,通过无压烧结方法制备AlN/YAlO_(3)复合陶瓷,研究不同温度下AlN/YAlO_(3)复合陶瓷的抗热震性能,分析热震前后AlN/YAlO_(3)复合陶瓷的物相结构、断口形貌和表面形貌,并阐明热震损伤机理。结果表明,在AlN陶瓷中加入YAlO_(3)能够促进AlN陶瓷的烧结,将致密度提升至98.37%,同时细化晶粒,提高AlN/YAlO_(3)复合陶瓷的抗弯强度和抗热震性能。在温度较高的热震试验中,当热震温度升高至600℃后,AlN/YAlO_(3)复合陶瓷的抗弯强度和残余强度保持率显著高于AlN陶瓷,表明添加YAlO_(3)能够有效提高AlN陶瓷的抗热震性能,这主要归因于微裂纹增韧及裂纹的偏折、分叉等机制的协同作用减缓了AlN/YAlO_(3)复合陶瓷抗弯强度的降低速度。此外,当热震温度达到1 000℃时,AlN发生氧化生成Al_(2)O_(3),导致AlN/YAlO_(3)复合陶瓷抗弯强度降低。

AlN ceramics have high hardness and brittleness,and it is difficult to be sintered and dense.As a smelting vessel,it is damaged by high-temperature deformation or thermal shock caused by temperature change.AlN/YAlO_(3) composite ceramics were prepared by pressureless sintering method by adding YAlO_(3) as a particle reinforcement phase,and the thermal shock resistance of AlN/YAlO_(3) composite ceramics at different temperatures was investigated.The phase structure,fracture morphology,and surface morphology of AlN/YAlO_(3) composite ceramics before and after thermal shock were analyzed,and the mechanism of thermal shock damage was elucidated.The results show that the addition of YAlO_(3) can promote the sintering and increase the density to 98.37%of AlN ceramics.The flexural strength and thermal shock resistance of AlN/YAlO_(3) composite ceramics are improved due to the grain refinement.Especially in thermal shock experiments at higher temperatures,when the thermal shock temperature rises to 600℃,the flexural strength and residual strength ratio of AlN/YAlO_(3) composite ceramics are significantly higher than those of AlN ceramics,indicating that the addition of YAlO_(3) can effectively improve the thermal shock resistance of AlN ceramics.It is mainly attributable to microcrack toughening,crack de ection and branching behavior slow down the reduction of flexural strength of AlN/YAlO_(3) composite ceramics.Moreover,when the thermal shock temperature reaches 1000℃,Al_(2)O_(3) oxidated by AlN reduces severely the flexural strength of AlN/YAlO_(3) composite ceramics.