Microstructure and mechanical properties of ZTA/BN machinable ceramics fabricated by reactive hot pressing
Microstructure and mechanical properties of ZTA/BN machinable ceramics fabricated by reactive hot pressing
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DOI：
10.1016/j.jeurceramsoc.2014.09.002
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发表时间：
2015-02
影响因子：
5.7
通讯作者：
B. Zhong;G. Zhao;X. Huang;L. Xia;X. Tang;Shengping Zhang;G. Wen
中科院分区：
文献类型：
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作者：
B. Zhong;G. Zhao;X. Huang;L. Xia;X. Tang;Shengping Zhang;G. Wen
采用反应热压法制备了氧化锆增韧氧化铝(ZTA)/氮化硼（BN）可切削陶瓷。通过氮化铝（AlN）和硼酸（H3BO3）的反应，将BN引入复合材料中。采用x射线衍射（XRD）、扫描电子显微镜（SEM）和透射电子显微镜（TEM）研究了ZTA/BN复合材料的微观结构。结果表明：BN晶粒均匀致密地分布在al2o3和zro2晶粒之间；相对密度、抗弯强度、断裂韧性和维氏硬度随温度升高而升高。在1800℃烧结时，BN含量为12.5 vol%的ZTA/BN复合材料的抗弯强度和断裂韧性分别达到731 MPa和7.48 MPa m1/2。这些数值远远高于采用常规粉末烧结方法制备的相同成分的复合材料，甚至高于单片ZTA陶瓷。断裂强度和断裂韧性的提高主要是由于反应热压法引入了氮化硼，阻止了氮化硼的聚集，减小了缺陷尺寸。ZTA/BN复合材料具有良好的切削性能，可以使用常规硬质合金钻头进行切削加工。
Zirconia-toughened alumina (ZTA)/boron nitride (BN) machinable ceramics have been successfully fabricated by reactive hot pressing. BN wasin-situintroduced into the composite by the reaction of aluminum nitride (AlN) and boric acid (H3BO3). The microstructure of ZTA/BN composite was investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) techniques. The results indicated that BN grains were uniformly and compactly distributed among Al2O3and ZrO2grains. The relative density, flexural strength, fracture toughness, and Vickers hardness increased with increasing temperature. The flexural strength and fracture toughness of the ZTA/BN composite with BN content of 12.5 vol% sintered at 1800 °C achieved high values of 731 MPa and 7.48 MPa m1/2, respectively. These values were much higher than those of the composite with the same composition prepared by conventional powder sintering method, and even higher than those of the monolithic ZTA ceramics. The enhancements of the fracture strength and fracture toughness were primarily ascribed to the reactive hot pressing method which introduced BNin-situand prevented the aggregation of BN and reduced the flaw sizes. The ZTA/BN composite exhibited excellent machinability and could be drilled using conventional cemented carbide drill bits.