共查询到18条相似文献,搜索用时 156 毫秒
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B4C--SiC/C复合材料氧化过程的TG/DTA分析 总被引:3,自引:0,他引:3
制备了B_4C-SiC/C复合材料,对不同组成的复合材料在201500℃升温氧化过程进行了TG/DTA(热重和差热联用)分析。结果表明,复合材料具有不同的高温抗氧化性能,此差异可归因于以下几方面:复合材料的组成不同(包括陶瓷粒子的种类、含量),不同种类的陶瓷粒子氧化转变成陶瓷氧化物的温度、速率不同,生成的陶瓷氧化物在高温下的物性(对基体材料的润湿性、粘度及流动性、挥发性和对氧的扩散系数等)不同。通过在炭基体中弥散B4C粒子可明显提高炭基体在850℃以下的抗氧化性。当复合材料中B4C含量较高而SiC含量低时,样品表面将趋于形成B2O3较为富集的硼硅酸玻璃相,在1500℃以下具有良好的氧化防护效果;当样品中SiC含量较高时,在高温下(>1200℃),随着部分B2O3的挥发和大量SiO2的生成,样品表面将趋于形成SiO2较为富集的硼硅酸盐玻璃相,在高达1400℃以上仍具有良好的氧化防护效果 相似文献
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C/C复合材料的高温抗氧化研究进展 总被引:20,自引:1,他引:20
以设计思路的发展演化为线索,结合国内外近年的研究报道,从选材的性能要求、组成、抗氧化机理、成功范例及制备工艺的角度出发,分别对抗氧化涂层技术以及抗氧化基体改性技术进行了介绍。特别选取了近年在碳/碳复合材料抗氧化研究中报道较少的制备技术进行详细介绍,其中包括涂层技术中的超临界态流体工艺、溶胶-凝胶法、熔浆法、PACVD法以及基体改性技术的快速致密化工艺。这一领域内的中外研究也进行了对比,并在文章最后提出了对于碳/碳复合材料高温氧化保护研究方向的一些看法。 相似文献
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炭/炭复合材料抗氧化研究 总被引:21,自引:5,他引:16
C/C复合材料抗氧化问题是该领域的研究重点。本文根据我校的研究工作论述了C/C 复合材料的氧化过程及机理,讨论了不同阶段活化能变化的规律,对C/C复合材料抗氧化涂层进行概略分类,介绍了几种先进的涂层及制备方法,并就C/C 复合材料抗氧化发展和研究的前沿问题提出一些见解。 相似文献
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B4C/C复合材料高温氧化过程中的结构变化模型的研究 总被引:5,自引:0,他引:5
在用混合磨碎法制备B4C/C复合材料的基础上,考察了不同条件对复合材料氧化失重速率的影响,然后讨论了上述各因素对复合材料抗氧化性能的影响机制,并对复合材料结构与其自愈合功能的性进行了分析,在此基础上建立了复合材料高温氧化过程的结构变化模型。 相似文献
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纤维含量对C/C复合材料力学性能的影响 总被引:11,自引:0,他引:11
研究了炭纤维含量对C/C复合材料力学性能的影响,用扫描电镜(SEM)对材料的断口进行分析,结果表明:当炭纤维的体积分数小于8.3%时,随着炭纤维体积分数的增加,复合材料的抗折强度逐渐升高;之后,随着炭纤维的体积分数的增加,复合材料的抗折强度逐渐下降,短纤维增强C/C复合材料的断口特征为大量纤维拔出,其断裂过程为界面破坏所控制。 相似文献
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C/C复合刹车材料及防氧化技术研究进展 总被引:3,自引:0,他引:3
介绍了C/C复合刹车材料的发展进程,国际上主要的飞机刹车机轮公司C/C复合材料及防氧化涂料的生产技术和工艺特点,C/C复合刹车材料的特性以及国内C/C复合刹车材料制备和防氧化技术的部分情况。 相似文献
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C—SiC—B4C复合材料的非等温氧化 总被引:1,自引:1,他引:0
研究B4C/SiC值不同的三种C-SiC-B4C复合材料在非等温氧化过程中的失重/增重行为。发现B4C/SiC值不同.复合材料的氧化行为有较大差异.当B4C/SiC值为0.2时,复合材料在773~1573K的实验温度区间内表现为净失重;当B4C/SiC值为0.4和0.6时,则在不同的温度区间出现不同程度的增重现象,B4C/SiC值越大,增重越明显;高温(1473K以上)氧化时,B4C/SiC值越大则氧化速率越大。SEM观察到复合材料氧化后.表面生成完整或部分完整的氧化物玻璃保护层,其完整程度大致与复合材料的氧化失重结果相一致。 相似文献
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Y.G. Tong Z.H. Cai S.X. Bai Y.L. Hu M.Y. Hua W. Xie Y.C. Ye Y. Li 《Ceramics International》2018,44(14):16577-16582
C/C-SiC composites were fabricated via Si-Zr reactive alloyed melt infiltration using various C/C preforms with different porosities as reinforcements. The influence of preform porosities on the microstructure, mechanical strength and ablation resistance of the as-prepared composites were investigated. The results indicated that microstructure and properties of the C/C-SiC composites seriously depended on C/C preform porosities. The composites were mainly composed of carbon, SiC and ZrSi2 phases, while some residual silicon still existed in the composites prepared with very large porosity preforms. Flexural strength of the composites firstly increased with increasing C/C preform porosities, then reached the highest value, 307?MPa, and finally turned to decrease with the further increasing of preform porosities. Densities of the composites increased with increasing preform porosities, while open porosities were generally small below 7%. Linear ablation rates of the composites firstly sharply decreased with increasing preform porosities and then slightly decreased to reach a balance value. In a word, C/C preform porosity was of great significance for reactive melt infiltration of C/C-SiC composites. Densities, microstructure, mechanical strength and ablation resistance of the resulting composites should be comprehensively taken into consideration to choose an optimal preform porosity for fabrication of C/C-SiC composites. 相似文献
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《Ceramics International》2022,48(1):525-539
C/C-BN composites and Cf/BN/PyC composites exhibiting different structures for pyrolytic carbon (PyC) and boron nitride (BN) were studied comparatively to determine their oxidation behavior. This study used five types of samples. Porous C/C composites were modified with silane coupling agents (APS) and then fully impregnated in water-based slurry of hexagonal boron nitride (h-BN); the resulting C/C-BN preforms were densified by depositing PyC by chemical vapor infiltration (CVI), resulting in three types of C/C-BN composites. The other two Cf/BN/PyC composites were obtained by depositing a BN interphase and PyC in carbon fiber preforms by CVI; one was treated with heat, and the other was not. This study was focused on determining how the PyC deposition mechanism, morphology and pore structure were affected by the method of BN introduction. In the 600–900 °C temperature range, the Cf/BN/PyC composites and C/C composites underwent oxidation via a mixed diffusion/reaction mode. The C/C-BN composites had a different pore structure due to the formation of nodules comprising h-BN particles; both interfacial debonding and cracking were reduced, resulting in higher resistance to gas diffusion, lower oxidation rate and larger activation energy (Ea) in the temperature range 600–800 °C. In addition, the mechanism for oxidation of C/C-BN composites gradually exhibited diffusion control at 800–900 °C because the formation of h-BN oxidation products healed the defects. The oxidation mechanism was more dependent on pore structure than on BN structure or content. 相似文献