纳米Al2O3增韧MoSi2复合陶瓷的性能及机理研究

Properties and Mechanism of Nano-Al2O3 Toughened MoSi2 Composite

为了进一步改善MoSi2材料较低的室温断裂韧性,在实验中将不同体积分数的纳米Al2O3粉与Mo粉、Si粉(钼硅摩尔比为1∶2)湿磨混合,通过真空反应热压烧结的方式制得MoSi2复合陶瓷,并测试其致密度、硬度以及断裂韧性等物理性质.采用XRD、SEM和EDS等手段分别对所制得的样品的物相组成、微观形貌和微区元素成分进行分析,探讨了掺入不同体积分数的纳米Al2O3粉对MoSi2复合陶瓷性能的影响.结果表明:相对单一MoSi2相,掺入一定量纳米Al2O3能够有效改善Mo Si2材料的物理性能;当掺入纳米Al2O3体积分数为20%时,其致密度、硬度及断裂韧性分别提升到原来单一MoSi2的102%、119%、167%;随着纳米Al2O3加入量继续增多,其在MoSi2基材料中的分散性下降,也导致MoSi2复合陶瓷物理性能下降.

In order to further improve the low fracture toughness of MoSi2 materials at room temperature,nano Al2O3 powder with different volume fraction was mixed with Mo powder and Si powder(molar ratio of molybdenum and silicon is 1∶2)in this experiment.Mo Si2composite ceramics were prepared by thermal pressure sintering through vacuum reaction and physical properties such as density,hardness and fracture toughness were tested.The phase composition,micro-morphology and micro-elemental composition of the prepared samples were analyzed by XRD,SEM and EDS.The effects of nano-Al2O3 powder with the different volume fractions on the properties of MoSi2 composite ceramics were discussed.The results showed that compared to a single MoSi2 phase,the incorporation of a certain amount of nano-Al2O3 could effectively improve the physical properties of MoSi2 materials.When the volume fraction of nano-Al2O3 was 20%,the relative density,hardness and fracture toughness of the MoSi2 increased to 102%.119%,167%,respectively.As for the amount of nano-Al2O3 continues to increase,the dispersibility of nano-Al2O3 in the MoSi2-based material decreased,resulting in the decrease of the physical properties of the MoSi2 composite ceramic.