【作者】 向阳；

【导师】 陈朝辉； 王松；

【作者基本信息】 国防科学技术大学 ， 材料科学与工程， 2008， 硕士

【摘要】 在碳纤维增强碳化硅(Cf/SiC)复合材料表面制备涂层对提高Cf/SiC复合材料抗氧化、抗冲刷能力具有重要的作用。本文在全面综述Cf/SiC复合材料表面涂层以及超高温陶瓷涂层研究进展的基础上,针对现有Cf/SiC复合材料抗氧化、抗冲刷性能存在的不足,开展Cf/SiC复合材料超高温陶瓷涂层制备及性能研究,旨在提高Cf/SiC复合材料抗氧化、抗冲刷能力,拓宽其应用范围。研究涂刷法和包埋法两种工艺制备了Cf/SiC复合材料超高温陶瓷涂层,并通过强度测试、扫描电镜、X射线衍射等测试手段对涂层组成、结构以及性能进行了分析。采用涂刷法在Cf/SiC复合材料表面制备ZrB2-SiC超高温陶瓷涂层,通过对涂层体系的设计,选择以二硼化锆、碳化硅和硼3种微粉为体系组元,以聚碳硅烷-二乙烯基苯体系为粘结剂,经低温固化以及1200℃高温烧成在Cf/SiC复合材料表面制备了ZrB2-SiC超高温陶瓷涂层。采用正交实验进一步研究了组分配比对Cf/SiC复合材料表面涂层性能的影响,结果表明,当填料成分为60wt.% ZrB2,4wt.% SiC,6wt.% PCS,4wt.% B,26wt.% DVB时,涂层性能最佳。Cf/SiC复合材料表面涂层的界面结合强度为2.01 MPa,经1200℃氧化30min后,Cf/SiC复合材料的氧化失重率仅为0.54%,强度保留率为97.3%,而在相同的氧化条件下,未覆盖表面涂层的Cf/SiC复合材料的氧化失重率为10.37%,强度保留率为38.7%。采用包埋法工艺制备ZrC-Zr2Si超高温陶瓷涂层,Zr-Si在Cf/SiC复合材料表面发生化学反应,生成均匀致密的ZrC-Zr2Si涂层,该涂层的厚度在10μm左右,涂层的内层为ZrC,外层为ZrC和Zr2Si。采用正交实验进一步研究工艺参数对涂层性能的影响,结果表明,当体系含量为60wt.%Zr-Si,30wt.%PCS-DVB,10wt.%Al2O3时,在1400℃保温8小时,涂层性能最佳,界面结合以化学反应结合为主,涂层与基体的界面结合强度为7.41MPa,覆盖有该涂层的Cf/SiC复合材料在1200℃氧化30min后的氧化失重率仅为0.30%,强度保留率为92.5%,由此可见该涂层具有较好的抗氧化效果。ZrC-Zr2Si涂层通过硼化处理工艺,当保温温度为1200℃,保温时间为3h时,可以转化为均匀致密的ZrB2涂层,Cf/SiC复合材料在1200℃下的氧化失重率仅为0.13%,强度保留率为94.3%,经硼化处理后的试样表现出相对更优的性能。更多还原

【Abstract】 The coatings of carbon fiber reinforced silicon carbide (Cf/SiC) composites play crucial role in the anti-oxidation and anti-erosion properties of Cf/SiC composites. In this dissertation, the research & development of the coatings and ultra high temperature ceramics(UHTCs) coatings for Cf/SiC composites were reviewed at first, aiming to improve the anti-oxidation and anti-erosion properties of Cf/SiC composites, the coatings of Cf/SiC composites were fabricated and analyzed, and the techniques were optimized. In the paper, three coating systems were fabricated via brushing process and pack cementation method respectively in order to improve the high temperature resistance of Cf/SiC composites. The oxidation resistance, the microstructures and the compositions of the coating systems were investigated by means of some techniques such as flexural strength test, scanning electron microscope (SEM) and X-ray diffraction (XRD).The ZrB2-SiC coating was fabricated via brushing process using PCS-DVB as binder and ZrB2、SiC and B powders as fillers according to the design of the coating system. When solidified at low temperature and sintered at 1200℃,the ZrB2-SiC coating was fabricated at the surface of Cf/SiC composites, then the effect of the proportion of ceramic powders on the performance of coated Cf/SiC composites was studied by designing an orthogonal experiment. The results show that when the filler was composed of 60wt.%ZrB2, 4wt.% SiC, 6wt.%PCS, 4wt.%B and 26wt.%DVB, the coating showed the best performance, the adhesive strength was 2.01MPa. After soaked at 1200℃for 30min under static air, the coated Cf/SiC composites retained 99.46% of original mass and 97.3% of original flexural strength. While the uncoated Cf/SiC composites retained 89.63% of original mass and 38.7% of original flexural strength.The other two coating systems were fabricated via pack cementation method. The ZrC-Zr2Si coating , homogeneous and density, was formed through the reaction of Zr-Si with Cf/SiC composites, whit the thickness was 10μm, the coating was composed of a ZrC inner layer and a ZrC-Zr2Si outer layer. An orthogonal experiment was designed to investigate the influences of the process condition. It was found that the optimizing infiltration composition and process was: 60wt..%Zr-Si, 30wt..%PCS-DVB, 10wt..%Al2O3, holding 8 hours at 1400℃in Ar protecting atmosphere. The bond between coating and Cf/SiC composites was mainly metallurgical bond, so the adhesive strength was as high as 7.41MPa. After soaked at 1200℃for 30min under static air, the coated Cf/SiC composites retained 99.70% of original mass and 92.5% of original flexural strength. The coating had the remarkably improvement of oxidation-resistance of Cf/SiC composites. After reaction with B, when held for 3 hours at 1200℃in Ar protecting atmosphere, the ZrC-Zr2Si coating was translated to the ZrB2 coating which was homogeneous and density. After soaked at 1200℃for 30min under static air, the coated Cf/SiC composites retained 99.87% of original mass and 94.3% of original flexural strength. Compared to the ZrC-Zr2Si coating, the ZrB2 coating showed the better performance.更多还原