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Ni/SiO2催化制备炭/炭复合材料研究 总被引:1,自引:0,他引:1
利用常规化学气相渗透工艺,在针刺炭布预制体中添加3.5%,4.O%Ni/SiO2负载型金属催化剂,以丙烯作碳源气体,在750-900℃下,经过100h的沉积,炭/炭(C/C)复合材料的密度达到1.65g/cm^3,其催化沉积炭的速率比不舍催化剂时提高了3倍以上。该材料经高温处理后,氧化失重率低,氧化起始温度高。应用扫描电镜(SEM),X射线衍射分析(XRD)和光学显微镜观察了基体炭的形貌,分析了催化沉积炭和抗氧化机理。实验结果证明,用该催化化学气相渗透法制备C/C复合材料,周期短,成本低,抗氧化性能好。 相似文献
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炭基体结构状态对C/C复合材料抗烧蚀性能的影响 总被引:12,自引:2,他引:12
碳基体在C/C复合材料的组成中占有很大的比重,因此炭基体不同的结构状态往往对C/C复合材料的各项性能有显著的影响。本文利用不同的原料和加工工艺制备出了三种具有不同炭基体的C/C复合材料,这三种碳基体分别是热解炭,沥青炭以及解热炭-树脂炭混合炭基体。对这三种材料多项性能的测试结果表明,炭基体的结构状态如石墨化度,炭片层结构的取向度的不同对C/C复合材料的各项性能均有显著的影响;基本趋势是C/C材料的石墨化度越高,材料的导电性能,导热性能以及抗烧蚀性能越好,压缩强度越低。三种炭基体中沥青炭基体沿纤维轴向的取向度最低,其抗烧蚀性能最差。 相似文献
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生命周期评价法(LCA)是指用数学物理方法结合实验分析对某一过程、产品或事件的资源、能源消耗,以及废物排放、环境吸收和消化能力等环境负担性能进行评价,以定量确定该过程、产品或事件的环境合理性及环境负荷量大小的一种新型研究方法。输入/输出法是LCA中的一种重要方法,本研究利用该方法对炭/炭(C/C)复合材料两种制备工艺(等温和热梯度化学气相渗透)中的资源、能源消耗以及污染物排放进行了定量评估。结果表明,与热梯度工艺相比,等温化学气相渗透法消耗了更多的资源、能源,给环境造成了严重的负荷,等温化学气相渗透法需改进,热梯度化学气相渗透工艺有广阔的应用前景。 相似文献
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采用轴棒法4D预制体、煤沥青为前驱体,经过常压、高压相结合的液相浸渍一炭化的致密工艺,制备出高密度轴棒法C/C复合材料。研究了轴棒法C/C复合材料的微观结构及其对轴向室温、高温(2800℃)拉伸破坏形式的影响。结果表明:轴棒法C/C复合材料轴向增强体采用炭棒,出现了一个特殊的界面,即炭棒与基体的“间隙”,主要原因是炭棒内部结合较强和纤维、基体的热膨胀系数不匹配而引起的;间隙的存在,使得轴棒法C/C复合材料的轴向室温、高温拉伸破坏形式出现较大差异,室温拉伸由于界面结合强度弱而引起的炭棒完整的拔出,未起到纤维应有的增强作用;高温拉伸却由于受热膨胀,间隙愈合,界面结合变强,试样从有效部位断裂,纤维增强作用明显提高。 相似文献
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《Ceramics International》2022,48(16):22985-22993
In this study, C/C–SiC and C/C–SiC–ZrC composites were prepared via chemical vapor infiltration and polymer infiltration pyrolysis, and the ablation mechanism under hypersonic oxygen-rich environmental conditions was investigated. The C/C–SiC composites demonstrate an excellent ablation resistance in a hypersonic oxygen-rich environment with a relatively low temperature and speed of approximately 1800 K and 1100 m/s, respectively. It is only in the ablation center area with higher temperatures that a certain degree of thermochemical ablation was observed. The mass and linear ablation rates of C/C–SiC composites (0.027 g/s and 0.117 mm/s, respectively) showed a significant increase in a hypersonic oxygen-rich environment with a temperature and velocity of approximately 2050 K and 2000 m/s, respectively. The high-temperature ablation resistance of ZrC-modified C/C–SiC–ZrC composites improved significantly. However, the ZrC ceramic component had a considerable impact on the ablation resistance of the material. The structural integrity of C/C–20SiC–30ZrC composites was relatively high in hypersonic oxygen-rich environments with a jet temperature and velocity of 2050 K and 2000 m/s, respectively, and mass and linear ablation rates were 0.012 g/s and 0.015 mm/s, respectively. When the ZrC content increased by 40%, the ablation resistance of the composite reduced significantly, whereas the mass and linear ablation rates increased to 0.043 g/s and 0.130 mm/s, respectively. 相似文献
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多晶硅用直拉法(CZ)或磁场直拉法(MCZ)拉制成单晶硅棒。晶体生长炉热场零件中的石墨发热体、坩埚等在机械应力和热应力的综合作用下发生变形或损坏造成失效,更换频繁。选用纯度高的炭纤维制成待制件的多孔坯体,经过增密、纯化处理制成炭/炭复合材料坩埚。试制的两体12″炭/炭复合材料坩埚进行了工业性试验。炭/炭复合材料机械强度高、耐热冲击性能和化学稳定性好,其使用寿命大大高于高纯石墨坩埚。两体的连接止口的氧化侵蚀限制了坩埚的使用寿命。单晶硅设备的大型化、炭/炭复合材料势必成为晶体生长炉热场零件的必选材料。 相似文献
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Shraddha SinghV.K. Srivastava 《Ceramics International》2011,37(1):93-98
The electrical properties of carbon/carbon (C/C) and carbon/carbon-silicon carbide (C/C-SiC) ceramic composites were measured. The results show that the capacitance decreases rapidly with an increase in frequency and it becomes constant above a frequency of 500 kHz, whereas the dissipation factor increases with increasing frequency. C/C-SiC composites give higher value than C/C composites due to the presence of microcracks. 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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Ze Yu Wang Man Ni Li Jin Ba Qiang Ma Zeng Qi Fan Jing Huang Lin Zheng Xiang Zhong Jun Lei Qi Jian Cao Ji Cai Feng 《Journal of the European Ceramic Society》2018,38(4):1059-1068
Brazing C/C composite to Nb is often associated with the problem of high residual stress, resulting in low-strength joints. To overcome these problems, here we carried out a simple polymer carbonization process to acquire uniform carbon-covered Cu foam composite interlayer, which was subsequently used for soundly brazing C/C composite and Nb with the assembly of C/C composite/Ag-Cu-Ti foil/C-Cu foam/Ag-Cu-Ti foil/Nb. Microstructure and mechanical properties of the joints were well investigated. The carbonization reacted with Ti elements, forming uniformly distributed in-situ TiC nano-flakes in the joint seam by virtue of the porous Cu foam skeleton. Results present that the in-situ TiC nano-flakes not only greatly reduced the thermal expansion coefficient but also effectively impeded the Cu solid solutions agglomeration. The average shear strength of the joint brazed with 3% C-Cu (wt.%) foam interlayer reached ~52.8 MPa with the brazing temperature of 880 °C for 10 min. 相似文献