氮化硼对锆刚玉莫来石材料力学性能及显微结构的影响

^^EFFECT OF BN ADDITIVE ON MECHANICAL PROPERTIES AND MICROSTRUCTURE OF CORUNDUM-MULLITE-ZIRCONIA MATERIALS

研究了锆刚玉莫来石－氮化硼夏合材料的显微结构及力学性能，结果表明：在锆刚玉莫来石基质中引入氮化硼，降低材料的抗折强度，但可提高断裂韧性。这是氮化硼的微裂纹增韧作用所致。氮化硼的编织状结构可阻碍晶界的滑移，降低材料高温强度的衰减率。材料内生成的针状９Ａｌ＿２Ｏ＿３·２Ｂ＿２Ｏ＿３，在断裂过程中产生拔出效应，有利于力学性能的提高。

The micostructure and mechanical properties of corundum-mullite-zirconia/boron nitridecomposites have been studied.The results indicate that addition of boron nitride to corundum-mullite-zirco-nia material leads to decrease in modulus of rupture and increase in fracture toughness,which may be mainly attributed to the presence of microcracks.BN interwoven microstructure will prevent grain boundary slip and reduce the attenuation rate of high temperature strength.Needle shaped 9Al_2O_3·2B_2O_3 crystals formed in the material will create a pull-out effect when the material approaches to fracture,which may be beneficial to the enhancerment of mechanical properties.