【作者】 龙莹；

【导师】 熊翔； 肖平；

【作者基本信息】 中南大学 ， 材料学， 2012， 博士

【摘要】 C/C复合材料表面抗氧化涂层材料及含纤维陶瓷界面相C/C复合材料应尽量避免以牺牲复合材料力学性能为代价,因此,有必要全面研究和掌握制备工艺对材料微观结构和微观力学性能的影响,在有效控制制备成本、提高抗氧化性能的前提下提高材料的力学可靠性和使用寿命。本文主要研究了C/C复合材料表面SiC、TaC和ZrC陶瓷涂层及含PyC-(SiC)-TaC-PyC纤维陶瓷界面相C/C复合材料的微观结构和微观力学性能,建立了制备工艺-微观结构-微观力学性能之间的相互关系。其主要工作和结论为：1)采用化学气相沉积工艺,分别在1100℃、1200℃和1300℃及离化学气相沉积反应器进气口340mm.380mm和420mm沉积位置制备了SiC涂层,研究了沉积温度和沉积位置对涂层微观结构和微观力学性能的影响。并研究了沿厚度方向非均匀沉积SiC涂层的力学性能分布。同时,以含游离Si或C的SiC涂层为研究对象,研究了游离Si或C对涂层的微观结构和微观力学性能。2))研究了1100℃、1200℃和1300℃三个沉积温度对TaC涂层微观结构和微观力学性能的影响。对非均匀TaC涂层沿厚度方向进行结构和力学表征,研究了微观结构和微观力学性能之间的相互关系。分析了TaC涂层中游离C对涂层微观力学性能的影响。并以共沉积的游离碳为拉曼应力敏感因子,采用拉曼光谱法研究了非均匀沉积TaC涂层沿厚度方向的应力分布。3)研究了沉积位置对ZrC涂层沉积速率、成分、微观结构和微观力学性能的影响。通过比较化学计量比ZrC和非化学计量比C0.85Zr涂层微观结构和微观力学性能,研究了化学计量比对ZrC涂层力学性能的影响。4)利用纳米压痕仪,采用单根纤维顶出试验法研究了PyC-(SiC)-TaC-PyC复合界面相对C／C复合材料界面剪切强度的影响。并借用已有数学模型,研究了界面热应力对复合材料界面剪切强度的影响。综上所述,本文研究了C／C复合材料表面SiC、TaC和ZrC涂层及含PyC-(SiC)-TaC-PyC界面相C／C复合材料微观结构和微观力学性能,为合理设计C/C复合材料界面相及表面涂层,提高C/C复合材料可靠性和使用寿命起到了指导作用。更多还原

【Abstract】 The improvement of the anti-oxidation properties of C/C composites with ceramic interlayers and ceramic external coatings shouldn’t at the cost of sacrificing their mechanical properties. Therefore, it is necessory to investigate the influences of preparation processes on micro-structure and-mechanical properties of materials in order to improve their realibility and lifetime and while controlling the production cost effectively. In the present work, the microstructure and mechanical properties of SiC, TaC and TaC external coatings on C/C composites and C/C composites with PyC-(SiC)-TaC-PyCmulti-interlayer are invesigated. Meanwhile, the relationships among the processing, microstructure and mechanical properties of the materials are bulit. The main research content and conclusions are as follows:1) SiC coatings were produced by chemical vapor deposition at1100℃、1200℃and1300℃C and340mm、380mm and420mm substrate position from the inlet of the CVD reactor. The effect of deposition temperature and substrate position on microstructure and mechanical properties of the coatings were investigated. Meanwhile, the effect of free Si or C in the SiC coatings on microstructure and mechanical properties were studied.2) The effect of deposition temperature(1100℃、1200℃and1300℃) on microstructure and mechanical properties of TaC coatings were investigated. The relationship between microstructure and mechanical properties of TaC coatings with non-uniform structure through-the-thickness of the coating were analyzed. The effects of free C on mechanical properties of TaC coating were also studied. Meanwhile, treat the free C as stress-sense factor, the residual stress through the thickness of the TaC coating were evaluated.3) The effects of substrate position on microstructure and mechanical properties of the ZrC coatings were investigated. And the effects of stoichiometric ratio of ZrC coatings on mechanical properties effects of stoichiometric ratio of ZrC coatings on mechanical properties were studied by comparing the microstructure and mechanical properties of ZrC and C0.85Zr coating。4) The effect of PyC-(SiC)-TaC-PyC multi-interlayers on interfacial shear strength of C/C composites were investigated by single fiber push out tests by using nano-indentation. The effects of residual stresses on interfacial shear strength were studied by employing Huesh’s model.In a word, in the present work, the microstructure and mechanical properties of external coatings on C/C composites and composites with PyC-(SiC)-TaC-PyC interlayers were investigated. It is helpful for designing coatings and interface of C/C composites and improving its reliability and lifertime.更多还原