共查询到19条相似文献,搜索用时 109 毫秒
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采用甲基三甲氧基硅烷和二甲基二甲氧基硅烷对硅溶胶进行改性制得有机硅改性硅溶胶封孔剂,并通过浸渍和加热固化的方法对多孔Al2O3陶瓷片进行封孔处理。研究了固化温度和固化时间对封孔Al2O3陶瓷片绝缘性能的影响,并对多孔Al2O3陶瓷片封孔前后的微观结构进行了表征。结果表明,较佳封孔条件为固化温度120℃、固化时间60 min,此时封孔Al2O3陶瓷片的直流和交流击穿电压分别达到最大值10.76 kV和6.01 kV,1 000 V绝缘电阻不低于9 999 MΩ。封孔Al2O3陶瓷片表面为改性硅溶胶涂层,呈致密无孔隙状态且与基体结合紧密,涂层厚度约为25μm,表面水接触角提高到86.93°,封孔层深度约为10μm。 相似文献
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船舶热力管道的腐蚀与防护 总被引:1,自引:0,他引:1
对船舶热力管道的腐蚀原因及规律进行了分析,在对喷涂材料、蚀洗封孔涂料等方面进行研究的基础上,得出了“热喷涂稀土铝层 无机富锌蚀洗封孔涂层 耐高温面涂层”的复合涂层保护方案。 相似文献
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Coated pore-forming agent method (CPFAM) was introduced to improve the pore-forming agent method (PFAM) for the preparation of porous silicon nitride ceramics. Using SEM in combination with measurements of porosity and flexural strength, it has been found that the flexural strength of the porous silicon nitride ceramics produced with the CPFAM method is significantly higher than those without the coating process: a 100% increase in flexural strength for samples with a porosity of 50%. The porous silicon nitride ceramics also have a very low dielectric constant, which is ideal for applications in wave-transmitting systems. The enhanced mechanical strength of the silicon nitride made by the CPFAM method is a result of a more uniform distribution of the spherical pores and the formation of a dense layer of rod-like microstructures near the surface of the pores. 相似文献
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Strain Tolerant Porous Silicon Nitride 总被引:4,自引:0,他引:4
Yasuhiro Shigegaki Manuel E. Brito Kiyoshi Hirao Motohiro Toriyama Shuzo Kanzaki 《Journal of the American Ceramic Society》1997,80(2):495-498
An approach to material strain tolerance, which basically makes it possible to lower the elastic modulus while retaining strength, was experimentally confirmed using as an example a porous silicon nitride composed of oriented anisotropic grains and pores. The porous structure consisting of tightly tangled rodlike grains and anisotropic pores was obtained by using β-Si3 N4 whiskers. This material exhibited a low Youngs modulus while retaining a relatively high fracture stress, even though it contained 14.4% porosity. Consequently, the strain to failure of silicon nitride was appreciably increased. 相似文献
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Yongxing Zhang Min Zhao Jiaoxia Zhang Qian Shao Jianfeng Li Hang Li Bo Lin Meiyan Yu Shougang Chen Zhanhu Guo 《Journal of Polymer Research》2018,25(5):130
Silicon nitride was firstly used as anticorrosive pigment in organic coatings. An effective strategy by combining inorganic fillers and organosilanes was used to enhance the dispersibility of silicon nitride in epoxy resin. The formed nanocomposites were applied to protect Q235 carbon steel from corrosion. The anticorrosive performance of modified silicon nitride with silane (KH-570) was investigated by electrochemical impedance spectroscopy (EIS), water absorption and pull-off adhesion methods. With the increase of immersion time, the corrosion resistance as well as adhesion strength of epoxy resin coating and unmodified silicon nitride coating decreased significantly. However, for the modified silicon nitride coating, the corrosion resistance and adhesion strength still maintained 5.7×1010 Ω cm2 and 7.6 MPa after 2400-h and 1200-h immersion, respectively. The excellent corrosion resistance performance could be attributed to the chemical interactions between KH-570 functional groups and silicon nitride powders, which mainly came from the easy formation of Si-O-Si bonds. Furthermore, the modified silicon nitride coating formed a strong barrier to corrosive electrolyte due to the hydrophobic of modified silicon nitride powder and increased bonds. 相似文献
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Ceramic coatings prepared by sputtering and reactive sputtering were applied to reaction-bonded silicon nitride surfaces to prevent extensive oxidation of the underlying material. The high-density nitride-based coatings retard the oxidation of the substrate by forming an oxygen diffusion barrier which seals the open porosity while maintaining dimensional and thermal stability. The oxidation kinetics of the coated and uncoated reaction-bonded silicon nitride substrates were compared at T = 1000 ° to 1200°C. Oxidation of the underlying material in this temperature range was substantially reduced when suitable coatings were used and the crystalline oxidation product (cristobalite) was essentially eliminated. 相似文献
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《Journal of the European Ceramic Society》2017,37(1):69-74
Photovoltaic silicon is currently grown in silica crucibles coated with an oxidized silicon nitride powder, which acts as an interface releasing agent between the silicon and the crucible. A series of experiments was performed to study the reactions between coating components under high vacuum, varying the temperature, the holding time and the oxygen content in the coating. The results are discussed with the help of a simple analytical model taking into account the diffusive transport of reaction species from the inside of the porous coating to its surface and then their evaporation into the vapour phase. 相似文献
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《Journal of the European Ceramic Society》2002,22(14-15):2489-2494
In structural materials, pores are generally believed to deteriorate the mechanical reliability. This study, however, demonstrates pores can cause improved or unique performance when the porous microstructure is carefully controlled. The first example is a silicon nitride of 14% porosity fabricated by tape-castng whiskers. This material, where the characteristic fibrous grains were aligned uniaxially, shows a high fracture strength in excess of 1 GPa as well as high damage tolerance. The fracture energy obtained by a chevron-noteched beam technique was about seven times larger than that of dense silicon nitride, which was primarily attributable to grain “pull-out” mechanism enhanced by the pores. The other example was a silicon nitride of 24% porosity, fabricated by sinter forging technique which exhibited excellent strain tolerance. 相似文献
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《Journal of the European Ceramic Society》2017,37(1):75-82
Processing of photovoltaic silicon by solidification is currently carried out under argon flow in silica crucibles coated with an oxidized silicon nitride powder. A series of experiments was performed to study the reactions between coating components under argon flow by varying the temperature, the holding time and the oxygen content in the coating. The results are discussed with the help of a simple analytical model taking into account the diffusive transport of gaseous reaction species from the inside of the porous coating to the flowing argon. The conclusions drawn are used to discuss different practical aspects of the photovoltaic silicon crystallization process. 相似文献
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Duan Li Bin Li Xuejin Yang Shitao Gao Yuanyi Zheng 《Journal of the European Ceramic Society》2018,38(6):2671-2675
The in situ silicon nitride nanowires reinforced porous silicon nitride (SNNWs/SN) composites were fabricated via gelcasting followed by pressureless sintering. SNNWs were well distributed in the porous silicon nitride matrix. The tip-body appearance suggested a VLS growth mechanism. The flexural strength and elastic modulus of the prepared composites can achieve 84.3?±?3.9?MPa and 23.3?±?2.0?GPa respectively (25?°C), while the corresponding porosity was 40.7?vol.%. Remarkably, the strength retention rate of the composites at 1400?°C was up to 66.1%. This is due to the excellent thermal stability of SNNWs and silicon nitride matrix. Also, the fracture toughness of the composites was improved to ~42% larger than pure porous silicon nitride ceramics because of the bridging effect of the NWs and the interlocking effect of β-Si3N4 crystals. In addition, a good thermal shock resistance and dielectric properties were indicated. The good overall performance made SNNWs/SN composites promising candidate for advanced high-temperature applications. 相似文献