PAS烧结SiC/h-BN复相陶瓷的韧性表征

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英文篇名：Toughness Characterization of SiC/h-BN Ceramic Composites Prepared by PAS Sintering Process 作者：杨万利 ; 代丽娜 ; 樊振宁 ; 张瀚晨 ; 史忠旗 英文作者：YANG Wanli;DAI Lina;FAN Zhenning;ZHANG Hanchen;SHI Zhongqi;Chaoma Technology Co.Ltd,Xi'an Aerospace Composites Research Institute;School of Material Science and Engineering,Xi'an Jiaotong University; 关键词：碳化硅/六方氮化硼 ; 阻力曲线 ; 断裂韧性 ; 韧化比 英文关键词：silicon carbide/hexagonal boron nitride;;R-curve;;fracture toughness;;toughness ratio 中文刊名：CLDB 英文刊名：Materials Reports 机构：西安航天复合材料研究所超码科技有限公司;西安交通大学材料科学与工程学院; 出版日期：2019-04-25 出版单位：材料导报 年：2019 期：v.33 基金：中国航天科技集团有限公司科技创新研发项目(2017-12);; 国家“863”高科技项目(2012AA040209)~~ 语种：中文; 页：CLDB201908005 页数：4 CN：08 ISSN：50-1078/TB 分类号：25-28

摘要

为探讨等离子活化烧结(PAS)工艺制备的SiC/h-BN复相陶瓷的失效特性,采用三种韧性表征方式(断裂韧性K_(IC)、韧化比、R曲线)研究评判该类复相材料破坏的韧性依据,并对裂纹扩展的显微形貌进行分析与讨论,建立了复相陶瓷失效评价的模型。结果表明:SiC/h-BN复相陶瓷两种试样的K_(IC)都随着h-BN含量的增加而降低;以韧化比(TI)作为韧性指标,发现h-BN含量越多,复相陶瓷的韧性越好;结合R曲线可知,h-BN含量增多,复相陶瓷的R曲线呈陡峭的上升趋势,但却有着较低的裂纹扩展门槛值。由此可知,三种韧性表征结果之间存在着相互矛盾。基于显微形貌分析发现,复相陶瓷中存在的层状h-BN增加了能量耗损,裂纹在扩展过程中发生偏转、分叉和桥联等现象。以K_(IC)作韧性指标更多反映的是裂纹萌生的阻力,韧化比TI更多反映的是裂纹扩展的阻力。基于材料在工程应用中的不同应力状态,应选择合适的韧性参数来表征,才能更直接地指导复相陶瓷的应用及失效评价。
        In order to investigate the failure characteristics of SiC/h-BN ceramic composites prepared by the plasma activated sintering( PAS) process,three kinds of toughness characterization methods( fracture toughness K_(IC),toughness ratio and R curve) were used as the basis to toughness for failure judgment of these composites. The microstructure of crack extension was also analyzed and discussed,and the failure model of the composites was established. The results show that both K_(IC)was decreased with the h-BN content increase for the composites. The toughness ratio( TI) increased with the increasing h-BN content indicating the better toughness. Combined with the result of R curves,the composite with more h-BN content exhibited steeper rise R curve tendency,which had a lower crack extension threshold. So,there is a contradiction between the three kinds of toughness results. Based on the microstructure analysis,the h-BN plates existing in the composites could consume more fracture surface energy,and the cracks deflection,branching and bridging were occurred during cracks extension. Hence,K_(IC)as the toughness index reflected the resistance of crack initiation,and TI indicating the crack extension resistance. To guide the application and failure evaluation of these ceramic composites,proper parameter should be used to characterize toughness under the different stress state of materials in engineering application.

引文

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