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Influence of Thermal Shock on the Mechanical Behavior of Si-SiC Coated Carbon/Carbon Composites

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Journal of Materials Science & Technology 2009年第2期25卷 251-253页

作者： qiangang Fu Hejun li Yongjie Wang Kezhi li Lu Wei C/C Composites Research Center Northwestern Polytechnical University Xi＇an 710072 China

Si-SiC coating was prepared on the surface of carbon/carbon （C/C） composites by a two-step technique of pack cementation, and the influences of thermal shock between 1773 K and room temperature in air on the mechanical property and fracture behavior of the coated C/C were studied. The results show that, after thermal shock between !773 K and room temperature for 5, 10 and 15 times, the flexural strength of coated composites increases by 4.29%, 15.00% and 24.20%, respectively. The toughness of the coated C/C enhances gradually during the thermal shock test. The improvement of the mechanical property after the thermal shock test is primarily caused by the weakening of the fiber-matrix interface and the reduction of residual thermal stresses by thermal shock.

关键词： Carbon/carbon composites Coating Mechanical behavior

SiC/Si-W-Mo coating for protection of C/C composites at 1873 K

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Journal of University of Science and Technology Beijing 2008年第6期15卷 822-826页

作者： Dangshe Hou Kezhi li Hejun li qiangang Fu Yulei Zhang National Key Laboratory of Thermostructure Composite Materials Northwestern Polytechnical University Xi＇an 710072 China

In order to prevent carbon/carbon composites from oxidation at 1873 K, an efficient oxidation protective SiC/Si-W-Mo coating was prepared by a two-step pack cementation technique. The microstructures and the phase composition of the as-received multi-coating were examined by scanning electron microscopy （SEM） and X-ray diffraction （XRD）. It is seen that the compact multi-coating is composed of α-SiC, Si, and （WxMO1-x）Si2. Oxidation test shows that, after oxidation at 1873 K in air for 102 h and thermal cycling between 1873 K and room temperature for 10 times, the weight loss of the SiC/Si-W-Mo coated C/C composites is only 0.26%. The invalidation of the multi-coating is attributed to the formation of penetrable cracks in the coating. 2008 University of Science and Technology Beijing. All rights reserved.

关键词： C/C composites coating microstructure oxidation protection

W-Mo-Si/SiC Oxidation Protective Coating for Carbon/Carbon Composites

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Journal of Materials Science & Technology 2007年第4期23卷 559-562页

作者： Dangshe HOU Kezhi li Hejun li qiangang FU Jian WEI Yulei ZHANG National Key Laboratory of Thermostructure Composite Materials Northwestern Polytechnical University Xi＇an 710072 China

A W-Mo-Si/SiC double-layer oxidation protective coating for carbon/carbon （C/C） composites was prepared by a two-step pack cementation technique. XRD （X-ray diffraction） and SEM （scanning electron microscopy）results show that the coating obtained by the first step pack cementation was a thin inner buffer layer of SiC with some cracks and pores, and a new phase of （WxMo1-x）Si2 appeared after the second step pack cementation. Oxidation test shows that, after oxidation in air at 1773 K for 175 h and thermal cycling between 1773 K and room temperature for 18 times, the weight loss of the W-Mo-Si/SiC coated C/C composites was only 2.06%. The oxidation protective failure of the W-Mo-Si/SiC coating was attributed to the formation of some penetrable cracks in the coating.

关键词： C/C composites Coating Microstructure Oxidation

Effect of SiC whiskers on the oxidation protective properties of SiC coatings for carbon/carbon composites

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Rare Metals 2006年第1期25卷 58-62页

作者： SHI Xiaohong li Hejun FU qiangang li Kezhi ZHANG Xiulian The Key Laboratory of Superhigh Temperature Composites Northwestern Polytechnical University Xi＇an 710072 China

In order to effectively employ the unique high temperature mechanical properties of carbon/carbon composite substrates, SiC coatings reinforced by SiC whiskers were prepared by pack cementation method. The effect of SiC whiskers on the oxidation resistance properties of the single-layer coating and double-layer coating was investigated. SiC whiskers in the single-layer SiC coating have little effect on the anti-oxidation property but obviously improve the thermal shock property. The double-layer coating with inner-layer reinforced coating exhibits more perfect anti-oxidation ability than the double-layer coating with SiC inner-layer coating.

关键词： carbon/carbon composites SiC coating oxidation protection SiC whiskers

Effect of Mo/Si Ratio on the Microstructure and Oxidation Resistance of Si-Mo Coating for C/C Composites

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稀有金属材料与工程 2009年第A3期38卷 109-112页

作者： Zhang Yulei li Hejun Fu qiangang li Kezhi Ouyang Haibo C/C Composites Research Center Key Laboratory of Superhigh Temperature Composites Northwestern Polytechnical University Xi＇an 710072 China

Oxidation protective Si-Mo coatings were prepared by pack cementation on the surface of C/SiC coated carbon/carbon composites. The influences of Mo/Si mass ratio in the pack powders on the microstructure and oxidation resistance of the coating were investigated. It showed that with the Mo/Si ratio increasing from 0.1 to 0.4, the MoSi2 proportion and the dimension of cracks in the coating increased, and the oxidation protective ability of the coated specimens firstly increased and then decreased. The coating with the Mo/Si of 0.2 exhibited better oxidation protective ability because of its more suitable MoSi2 proportion and excellent microstructure than those with the Mo/Si of 0.1, 0.3 and 0.4, which could effectively protect C/C composites from oxidation at 1773 K in air for more than 100 h. The mass loss of the coated samples was primarily due to the reaction between C/C matrix and oxygen diffusing through the penetration cracks in the coating.

关键词：氧化硅钼涂层复合材料保护能力物理性能

Effect of Thermal Shock and Oxidation on Mechanical Property of Carbon/Carbon Composites with a Silicide Coating

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稀有金属材料与工程 2009年第A3期38卷 37-40页

作者： Fu qiangang li Hejun li Kezhi Shi Xiaohong Huang Min C/C Composites Research Center Laboratory of Ultrahigh Temperature Composites Northwestern Polytechnical University Xi＇an 710072 China

A SiC whisker-toughened MoSi2-SiC-Si coating was prepared on carbon/carbon (C/C) composites surface by a two-step technique of slurry and pack cementation, and the effects of thermal shock and oxidation on the mechanical property of the coated C/C were studied. The flexural strength of C/C composites was improved by 6.8% after coated by SiC whisker-toughened MoSi2-SiC-Si. After thermal cycle between 1773 K and room temperature in air for 10 times, the mass loss of the coated sample was 5.08% and the percentage of remaining strength was 81.97%. After oxidation at 1773K in air for 60 min, the mass loss of the coated sample was 2.57% and the percentage of remaining strength was 89.63%. The decrease of the flexural strength during the thermal cycle and oxidation tests was primarily due to the oxidation of C/C substrate resulting from the cracking of coating.

关键词：泥浆固井技术复合材料力学性能氧化涂层

Ce-based catalysts used in advanced oxidation processes for organic wastewater treatment: A review

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Journal of Environmental Sciences 2020年第10期32卷 109-116页

作者： lijun Niu Ting Wei qiangang li Guangming Zhang Guang Xian Zeqing Long Zhijun Ren School of Energy and Enuironmental Engineering Hebei University of TechnologyTianjin 300130China School of Enuironment and Natural Resource Renmin University of ChinaBeijing 100872China

Refractory organic pollutants in water threaten human health and environmental safety,and advanced oxidation processes (AOPs) are effective for the degradation of these *** play vital role in AOPs,and Ce-based catalysts have exhibited excellent ***,the development and application of Ce-based catalysts in various AOPs have been *** study conducts the first review in this rapid growing *** paper clarifies the variety and properties of Ce-based *** applications in different AOP systems (catalytic ozonation,photodegradation,Fenton-like reactions,sulfate radicalbased AOPs,and catalytic sonochemistry) are *** Ce-based catalysts suit different reaction systems and produce different active ***,future research directions of Ce-based catalysts in AOP systems are suggested.

关键词： Ce-based catalysts Water treatment Redox properties Oxygen vacancies Advanced oxidation processes

水体中沉积物氮和磷的释放机制及其影响因素研究进展

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湿地科学 2022年第1期20卷 94-103页

作者：李乾岗田颖刘玲张光明王洪杰中国人民大学环境学院北京100872 河北大学生态与环境治理研究所河北大学生命科学学院河北保定071002 河北工业大学能源与环境工程学院天津300401

水体中沉积物氮和磷的释放是导致水体富营养化的主要原因。综述了水体中沉积物氮和磷的主要赋存形态,总结了沉积物氮和磷释放途径及其描述方法;从沉积物性质、上覆水的理化性质、生物、水体的水量变化、扰动作用5个方面,归纳了水体沉积... 详细信息

水体中沉积物氮和磷的释放是导致水体富营养化的主要原因。综述了水体中沉积物氮和磷的主要赋存形态,总结了沉积物氮和磷释放途径及其描述方法;从沉积物性质、上覆水的理化性质、生物、水体的水量变化、扰动作用5个方面,归纳了水体沉积物氮和磷释放过程的影响因素;阐述了水体中溶解氧含量、水体pH和水温对沉积物氮和磷释放的影响;最后,对未来相关研究进行了展望。

关键词：沉积物氮磷释放水体影响因素

碳化硅纳米材料及其衍生碳在超级电容器领域的应用

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物理化学学报 2024年第2期40卷 58-75页

作者：刘慧敏李克智张欣殷学民付前刚李贺军西北工业大学陕西省纤维增强轻质复合材料重点实验室西安710072

超级电容器由于充放电速度快、循环寿命长、成本低、环境友好等特性在众多储能器件中脱颖而出。在各类电极材料中,碳化硅(SiC)纳米材料及其衍生碳因其高稳定性、优异的导电性等优势被认为是极具应用前景的超级电容器电极材料。本文首先... 详细信息

超级电容器由于充放电速度快、循环寿命长、成本低、环境友好等特性在众多储能器件中脱颖而出。在各类电极材料中,碳化硅(SiC)纳米材料及其衍生碳因其高稳定性、优异的导电性等优势被认为是极具应用前景的超级电容器电极材料。本文首先系统地阐述了SiC纳米材料及其衍生碳的常用制备方法;然后,详细综述了SiC纳米材料及其衍生碳在超级电容器应用中的研究进展,总结“高导电碳材料复合”、“杂原子掺杂”、“赝电容材料复合”、“多级孔结构的设计”、“化学活化”等电化学性能的提升策略;最后,对SiC纳米材料及其衍生碳在超级电容器储能领域中应用存在的挑战和机遇进行展望。

关键词：碳化硅碳化硅衍生碳双电层电容赝电容