摘要
采用热压烧结的方法制备Al2O3/TiCN-0.2%Y2O3复合陶瓷的结果,较详细地介绍了试样成分、热压温度对试样抗弯强度、断裂韧性、维氏硬度等力学性能的影响。结果表明:在热压温度低于1650℃时,各项力学性能随着热压温度的提高而提高,当热压温度为1650℃、压力为35 MPa,保温时间为30 min时,其抗弯强度、断裂韧性及硬度分别达到它们的最大值1015 MPa,6.89 MPa.m1/2和20.82 MPa。当热压温度高于1650℃时,导致TiCN分解作用加强导致密度下降,同时温度过高导致晶粒长大使力学性能下降。显微结构分析表明:由于稀土Y2O3的加入,生成少量的YAG相,抑制了Al2O3和TiCN晶粒长大,有助于提高含Y2O3的Al2O3/TiCN复合材料的断裂韧性。TiCN颗粒弥散在Al2O3晶界处,其晶粒尺寸在1μm左右,分布均匀,相互交织,抑制了晶粒生长,从而起到增韧补强作用,有利于材料力学性能的提高。从压痕裂纹尖端扩展情况的扫描电镜照片可以看出:基体与增强相多个晶粒构成裂纹桥联行为,并可能形成裂纹偏转、分支与桥联的共存区,主要起作用的是稀土强化TiCN颗粒弥散增韧机制,将复合材料的断裂韧性从5.94提高到6.89 MPa.m1/2。
Al2O3/TiCN composites were fabricated by hot pressing sintering. The effects of the sample composition and HP temperature were investigated. The results indicate that the composites sintered with Al2O3/TiCN with the mechanical properties such as bending strength etc. increase with increasing temperature below 1650 ℃. Its bending strength, fracture toughness, Vickers hardness are 1015 MPa, 6.89 MPa·m^1/2, 20.82 MPa respectively at 1650 ℃ for 20 min. Mechanical properties such as related density etc. decrease with increasing temperature when it is above 1650 ℃, because of their decomposability which give off N2 at higher temperature and rapid growth of crystals. The addition of Y2O3 forms YAG that inhibits crystals from growing. The formation of YAG increases bend strength, fracture toughness, cracks-initiation resistance and cracks-extension resistance, The SEM photographs of surfaces with different contents of Al2O3/TiCN indicate that TiCN grains are distributed uniformly in Al2O3 matrix and the size of grains is about 1 μm. The cracks which propagate into Al2O3 grains are often deflected by TiCN grains that observed by SEM of the extension of the tip of indentation crack. This result suggests that crack bridging by TiCN grains and/or Al2O3/TiCN bonded grains might occur. Therefore, it is considered that this crack deflection and crack bridging become more effective by this chain-like structure. It enhances the fracture toughness of composite from 5.94 MPa·m^1/2 to 6.89 MPa·m^1/2.
出处
《中国稀土学报》
CAS
CSCD
北大核心
2006年第6期705-709,共5页
Journal of the Chinese Society of Rare Earths
基金
辽宁省教育厅青年基金计划项目(05L374)
沈阳理工大学科技基金(BS04018)资助项目
作者简介
李喜坤（1971-），男，辽宁本溪人，博士，副教授；研究方向：复合材料;通讯联系人（E-mail：kunxi@163．com）
