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凝胶注模和反应熔渗SiC陶瓷基零件素坯缺陷控制及高温力学性能研究 预览

Green Body Defect Control and High Temperature Mechanical Properties of Gel-Casting/Reactive Melt Infiltration SiC Based Parts
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摘要 针对凝胶注模和反应熔渗SiC陶瓷零件由于炭黑团聚、含量不足引起的坯体宏观裂纹、残留硅含量过高等问题,提出了一种有效控制陶瓷组织缺陷与残硅含量、提升陶瓷零件高温力学性能的方法。以短碳纤维代替炭黑作为碳源,通过实验对比分析了碳纤维与炭黑在陶瓷浆料中的分散性,以及这两种碳源对陶瓷素坯质量的影响规律;采用扫描电子显微镜和X射线衍射等手段研究了碳纤维和SiC陶瓷微观结构及其物相组成,并探讨了碳纤维体积分数对反应熔渗SiC陶瓷基零件高温性能的影响规律。结果表明:较之炭黑,短碳纤维在陶瓷浆料中具有良好的分散性,干燥后陶瓷坯体内大尺寸气孔和裂纹等缺陷得到有效控制;在反应熔渗过程中,碳纤维溶解到液硅中并生成β-SiC取代残硅,填充了陶瓷坯体的剩余孔隙;当碳纤维体积分数增加时,陶瓷坯体中的残硅含量得到有效控制;碳化硅陶瓷高温(1 350℃)力学性能指标随着碳纤维体积分数增加,先增大后减小,当碳纤维体积分数为20%时达到最大,高温弯曲强度、断裂韧性分别为(343±19)MPa、(5.04±0.27)MPa·m^1/2。 To solve the problem of macro-crack and residual silicon content of SiC ceramic parts caused by the carbon black agglomeration and insufficient content,an effective method to control the micro-structure defect and residual silicon content and to improve the mechanical properties of SiC ceramic parts at high temperature was proposed.Short carbon fibers(CF)serve as the carbon source,the dispersibilities of carbon black and short carbon fiber in ceramic slurry were comparatively investigated and the influences of the two carbon sources on the quality of the green body were analyzed.The micro-structure and phase composition of the reaction infiltrated Cf/SiC ceramic were observed by SEM and XRD.The effects of carbon fiber content on high temperature bending strength and fracture toughness of the SiC ceramic were discussed.The results show that short carbon fibers better disperse in ceramic slurry,and large-size pores and cracks in the ceramic green body can be well controlled.When in the reactive melt infiltration process,the porous structure formed by carbon fiber and ceramic particles facilitate the infiltration of liquid silicon,and the carbon fiber dissolves in the silicon liquid and reacted formβ-SiC surrounding the carbon fiber surface.As the volume fraction of short carbon fiber increases(0 to 40%),the residual silicon content in the ceramic matrix decreases,and the high temperature(1 350℃)performance of the ceramic part increases firstly then decreases.When the short carbon fiber volume fraction gets 20%,the high-temperature flexural strength and fracture toughness reach the highest,343±19 MPa and 5.04±0.27 MPa·m 1/2 respectively.
作者 鲁中良 曹继伟 冯朋帅 李涤尘 卢秉恒 LU Zhongliang;CAO Jiwei;FENG Pengshuai;LI Dichen;LU Bingheng(State Key Laboratory for Manufacturing Systems Engineering,Xi’an Jiaotong University,Xi’an 710049,China;Collaborative Innovation Center for Advanced Aero-Engine,Beijing 100191,China)
出处 《西安交通大学学报》 EI CAS CSCD 北大核心 2019年第2期63-69,共7页 Journal of Xi'an Jiaotong University
基金 国家自然科学基金资助项目(51775418,51375372)。
关键词 凝胶注模 反应熔渗 碳化硅 短碳纤维 高温力学性能 gel-casting reactive melt infiltration silicon carbide short carbon fiber high temperature mechanical property
作者简介 鲁中良(1977—),男,副教授。
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