【作者】 张建东；

【导师】 康鹏超；

【作者基本信息】 哈尔滨工业大学 ， 材料学， 2008， 硕士

【摘要】 本文采用高能球磨,将Si、C混合粉体的浆料浸渗到碳纤维布中,利用热压烧结过程中Si、C的原位反应制备了C/C-SiC复合材料。利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)对复合材料进行了物相分析和形貌观察,并探讨了高能球磨和热压烧结的工艺参数。采用称重法进行了碳纤维及相应复合材料的等温氧化试验,并对其抗氧化性能及原因进行了分析。通过研究球磨时间、球磨转速、球料比、球磨气氛等因素对高能球磨Si、C粉体的影响,确定了适于原位反应的粉体的球磨工艺参数。在碳纤维表面制备稀土转化膜对碳纤维进行活化,有膜层的碳纤维在其表面易于生成SiC,而且膜层在高温下的作用要比低温下明显的多。通过XRD测试发现在1450℃烧结的情况下有α-SiC和β-SiC两相SiC生成,而且基体的结构不会因为烧结时间的变化而发生变化;当烧结温度升高到1800℃时,α-SiC会转变为该温度下的热力学稳定相β-SiC。烧结时间的延长和烧结温度的提高都可以有效的提高材料的致密度。复合材料热压烧结所采用的温度越高,则碳纤维表面的SiC层越均匀,在纤维表面铺展的越好。比较复合材料及C/C材料的抗氧化性能,复合材料的氧化失重率远低于C/C材料。氧化反应活化能结果表明,C/C-SiC复合材料的氧化活化能高于单一的C/C材料,复合材料的抗氧化性能得到提高。更多还原

【Abstract】 C/C-SiC composite was prepared by hot pressed sintering with in-situ reaction between Si and C powder, which was prepared through high-energy ball milling and then was mixed into slurry infiltration of carbon cloth. The microstructure of the composite was studied by Scanning Electron Microscope (SEM), and the phase analysis was carried out with X-ray Diffraction (XRD), also the process parameters of high-energy ball milling and hot pressed sintering were discussed. The isothermal oxidation-weight loss test of carbon fiber and the corresponding composite was carried out with weighing method. The anti-oxidation properties and mechanism of carbon fiber and the corresponding composite was studied.The influnce of milling time, milling speed, ratio of grinding media to material and milling ambience to the Si and C powder during high-energy ball milling was studied, and then the process parametres of high-energy ball milling fit for the in-situ reaction of the mixed powder was gained.Tombar thite conversion film was prepared on the surface of carbon fiber to activate carbon fiber. SiC was easily generated on a carbon fiber with Tombar thite conversion film on its surface, and the effect of the film was more obvious when sintered at higher temperature.α-SiC andβ-SiC were found by the XRD observation after 1450℃sintered, and the structure of matrix doesn’t change as the sintering temperature changes.α-SiC transformed into the thermodynamic stabilityβ-SiC when sintered at 1800℃. The density of material was effictively promoted as the sintering time and sintering temperature increasing. The higher the sintering temperature is, the more uniform the SiC film is, and the better the quality is.Through the comparison with the anti-oxidation properties of C/C material and corresponding composite, it was found that the oxidation weightlossness of the composite was less than that of C/C material. The activation energy of heat decompositions of C/C-SiC composite was higher than that of single C/C material, and anti-oxidation property was highly improved.更多还原