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排序方式: 共有109条查询结果,搜索用时 15 毫秒
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《Journal of the European Ceramic Society》2021,41(13):6196-6206
Creep properties of 2D woven CVI and PIP SiC/SiC composites with Sylramic™-iBN SiC fibers were measured at temperatures to 1650 °C in air and the data was compared with the literature. Batch-to-batch variations in the tensile and creep properties, and thermal treatment effects on creep, creep parameters, damage mechanisms, and failure modes for these composites were studied. Under the test conditions, the CVI SiC/SiC composites exhibited both matrix and fiber-dominated creep depending on stress, whereas the PIP SiC/SiC composites displayed only fiber-dominated creep. Creep durability in both composite systems is controlled by the most creep resistant phase as well as oxidation of the fibers via cracking matrix. Specimen-to- specimen variations in porosity and stress raisers caused significant differences in creep behavior and durability. The Larson-Miller parameter and Monkman-Grant relationship were used wherever applicable for analyzing and predicting creep durability. 相似文献
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介绍了一种面向电机控制的数字信号处理芯片DSP56F805,采用现场总线控制系统的设计思想, 设计并实现了一个基于以太网和CAN 总线的多电机的伺服控制系统.首先采用DSP56F805 来控制单个永磁同步伺服电机的运行,从而构成FCS(现场总线控制系统) 中的一个智能节点.然后利用CAN 总线把这些智能节点连接起来,构成一个含有多个永磁同步电机(PMSM)子控制系统的FCS,最后利用以太网构成远程控制系统.该系统通过PVT(位置-速度-时间)插值算法对运动曲线进行平滑处理以及运用离散PIP算法对运动过程加以控制.所设计的系统不但便于对多电机进行集中的监测和管理,而且可以实现系统中的各个PMSM间的相互通讯而达到协调工作的目的.实验结果表明,该系统控制精度高、响应速度快、低速运行平稳,同时还具有连接简单、系统可靠和易于实现等优点. 相似文献
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本文以低密度C/C复合材料为坯体,有机锆聚合物为前驱体,采用聚合物浸渍裂解法(PIP)制备C/C-ZrC复合材料,并对其微观结构、力学性能、烧蚀性能以及烧蚀机理进行了研究。结果表明ZrC在材料内分布均匀,密度为2.05g·cm~(-3)的C/C-ZrC复合材料其弯曲强度为89.70MPa,呈脆性断裂。经氢-氧焰烧蚀150s后其线烧蚀率为-2.2×10~(-3)mm·s~(-1),质量烧蚀率为-1.0×10-3g·s~(-1),远低于密度为1.86g·cm~(-3)的C/C复合材料(线烧蚀率:4.4×10~(-3) mm·s~(-1),质量烧蚀率:7.5×10~(-4)g·s~(-1));在烧蚀的过程中,ZrC表现出优先氧化,同时生成的ZrO_2阻挡层能有效阻挡热量的传递和氧气的渗透,提高了材料的抗烧蚀性能。 相似文献
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分析了低温预氧化过程对聚碳硅烷(PCS)先驱体结构的影响,研究了不同预氧化温度和时间下SiCf/SiC复合材料室温和高温介电性能的演变规律。结果表明:经预氧化处理后基体中的氧含量增加,生成具有低介电常数的Si CxOy相,且其含量随着预氧化温度的升高或时间的延长逐渐增加,SiC微晶和自由碳的含量均减少,因此SiCf/SiC复合材料的复介电常数明显降低,同时高温复介电常数的升高幅度显著减小。经260℃-6 h预氧化处理后,700℃时复合材料在整个X波段的反射率均达到-8 d B以下,高温吸波性能得到有效改善。 相似文献
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Wen Jin Zhou Si Yi Lu Sun Bei-zhi Wang Yi Li Guang-de Xing Zhong-fang Cao Jie He Heng-ping Xiang Yang 《Ceramics International》2018,44(14):16583-16588
Polymer infiltration pyrolysis (PIP) was used to prepare carbon fiber-reinforced silicon carbide (C/SiC) composites, and chemical vapor deposition (CVD) was employed to fabricate SiC coating. The oxidation behavior at 1700?°C and the flexural property at 1200?°C were tested. SiC coating exerted remarkable oxidation effects on PIP-C/SiC composites. In the absence of coating, PIP-C/SiC composites lost 29.2% of its mass, with merely 6.74% of the original flexural strength retained. In contrast, CVD-SiC coated PIP-C/SiC composites had the mass loss of 10.2% and the flexural strength retention ratio of 23.4%. In high-temperature tests, SiC coating played an important role in the flexural strength of PIP-C/SiC composites. The flexural strength of uncoated composites became 330.7?MPa, and that of coated ones reduced from 655.3 to 531.2?MPa. 相似文献
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在PIP制程中,影响产品的最终质量涉及到的因素有很多。文章简单介绍了PIP制程的定义,详细阐述了PIP制程中影响产品不良的因素种类,分析了每一种因素产生的原因及预防措施,并针对这些因素采取6西格玛先进管理方法中的相应对策来分析和解决问题。同时列举了实例,针对主要不良因素加以改善来降低产品的不良率,从而保证产品的质量以获取更大的经济效益。 相似文献
9.
《Journal of the European Ceramic Society》2023,43(4):1397-1406
Unidirectional SiCf/SiC composites (UD SiCf/SiC composites) with excellent mechanical properties were successfully fabricated by a modified PIP method which involved the preparation of film-like matrix containing carbon layer with a low concentration PCS solution followed by the rapid densification of composites with a high concentration PCS solution. Carbon layers were in-situ formed and alternating with SiC layers in the as-received matrix. The unique microstructure endows the composites with appropriate interfacial bonding state, good load transfer ability of interphase and matrix and load bearing ability of fiber, and great crack deflection capacity, which ensures the synergy of high strength and toughness of composites. It is also found that the fiber volume fraction in the preform makes a non-negligible effect on the distribution of interphase and matrix, of which the reasonable adjustment can be utilized to optimize the mechanical properties of composites. Compared with the composites only using high concentration PCS solution, the UD SiCf/SiC composites prepared by the modified PIP method exhibit superior mechanical properties. Ultrahigh flexural strength of 1318.5 ± 158.3 MPa and fracture toughness of 47.6 ± 5.6 MPa·m1/2 were achieved at the fiber volume fraction of 30%. 相似文献
10.
《Journal of the European Ceramic Society》2014,34(12):2913-2924
SiC-fiber/SiCN ceramic matrix composites were manufactured by means of polymer infiltration and pyrolysis. The fiber preform was made by slurry infiltration and winding using a computer-controlled winding module. Multiple infiltration steps using a Si–C–N precursor were included to increase the density. The influence of the sintering conditions on the microstructure of the CMC was demonstrated.Pipe sections made of the CMC materials were joined using a laser-supported heating technology with an Y–Al–Si–O glass–ceramic filler. The thermal response of the CMC components was controlled by the anisotropic thermal conductivity. Fast heating by laser beam was achieved for elements rotating in the direction of the fiber winding. SEM micrographs of the joints showed the good wettability of the CMC by the glass–ceramic filler. Nearly defect-free joints were obtained using a nitrogen process atmosphere. The laser-supported technology was shown to be promising for the joining of CMC components. 相似文献