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931.
E. Badisch C. Mitterer P. H. Mayrhofer G. Mori R. J. Bakker J. Brenner H. Stri 《Thin solid films》2004,460(1-2):125-132
Recently, several new solid lubricants and modern lubrication concepts have been developed to achieve lower friction and wear and thus longer lifetime in severe tribological applications. The aim of this study is to characterize tribo-layers formed during ball-on-disc testing on low-friction, Cl-containing TiN coatings deposited by plasma assisted chemical vapor deposition and to clarify their formation mechanism. Characterization of the transfer layers was done by optical microscopy, optical profilometry, Raman spectroscopy, Auger electron spectroscopy and X-ray photoelectron spectroscopy. Differential scanning calorimetry was used to provide information on the chlorine-influenced chemical reactions of the coatings in ambient air. Iron oxide layers of a thickness in the nm-range have been found on low-chlorine containing TiN coatings (<3 at.% Cl) showing friction coefficients of approximately 0.8, whereas on TiN coatings with higher chlorine contents (>3 at.% Cl) rutile layers were preferably formed, resulting in friction coefficients below 0.2. This self-lubrication mechanism can be explained by the in-situ formation of easy-shearable titanium oxides in the contact zone in the presence of humidity and oxygen. 相似文献
932.
Brazing of Ti3Al alloys with the filler metal NiCrSiB was carried out at 1273–1373 K for 60–1800 s. The relationship of brazing parameters and shear strength of the joints was discussed, and the optimum brazing parameters were obtained. When products are brazed, the optimum brazing parameters are as follows: brazing temperature is 1323–1373 K, brazing time is 250–300 s. The maximum shear strength of the joint is 240–250 MPa. Three kinds of reaction products were observed to have formed during the brazing of Ti3Al alloys with the filler metal NiCrSiB, namely, TiAl3 (TiB2) intermetallic compounds formed close to the Ti3Al alloy. TiAl3+AlNi2Ti (TiB2) intermetallic compounds layer formed between TiAl3 (TiB2) intermetallic compounds and the filler metal and a Ni[s,s] solid solution formed in the middle of the joint. The interfacial structure of brazed Ti3Al alloy joints with the filler metal NiCrSiB is Ti3Al/TiAl3 (TiB2)/TiAl3+AlNi2Ti (TiB2)/Ni[s,s] solid solution/TiAl3+AlNi2Ti (TiB2)/TiAl3 (TiB2)/Ti3Al, and this structure will not change with brazing time once it forms. The formation of over many intermetallic compounds TiAl3+AlNi2Ti (TiB2) results in embrittlement of the joint and poor joint properties. The thickness of TiAl3+AlNi2Ti (TiB2) intermetallic compounds increases with brazing time according to a parabolic law. The activation energy Q and the growth velocity K0 of the reaction layer TiAl3+AlNi2Ti (TiB2) in the brazed joints of Ti3Al alloys with the filler metal NiCrSiB are 349 kJ/mol and 24.02 mm2/s, respectively, and the growth formula was y2=24.04exp(−41977.39/T)t. Careful control of the growth of the reaction layer TiAl3+AlNi2Ti (TiB2) can influence the final joint strength. 相似文献
933.
Bukhanovskii V. V. Borisenko V. A. Kharchenko V. K. Mamuzic I. 《Strength of Materials》2004,36(2):195-202
Experimental data on the short-term strength and plasticity of niobium alloy 5VMTs of the system Nb–W–Mo–Zr in its initial state, after annealing, and with a silicide-ceramic protective coating obtained by testing in vacuum, an inert atmosphere, and in air in the temperature range from 290 to 2270 K are analyzed. The process of microcrack initiation and propagation in the protective coating and matrix is investigated in high-temperature static tension. The limiting plastic strain values have been established at which the composite retains its load-carrying capacity in high- temperature aggressive and oxidizing gas atmospheres. 相似文献
934.
Hot Dip Aluminized Coatings with different thickness were prepared on Q235 steel in aluminum solutions with different temperature for certain time. Through tensile tests and in-situ SEM observations, the effect of the coating's microstructure on the tensile strength of the samples was studied. It was disclosed at certain aluminum solution temperature,transaction layers mainly composed of Fe2 Al5 phase got thicker with time prolonging, and this changed initial crack's extending direction from parallel with to vertical with stretching direction. The change in crack direction decreased tensile strength of samples, thus made the coating easy to break. It was concluded that the existence of thick Fe2 Al5 phase layer was the basic reason for the lowering of tensile strength of the coating. 相似文献
935.
This paper reviews the past, present and future of surface modification of titanium alloy from the point of view of preparation of hard tissue replacement implants. The development of titanium alloy is also described. 相似文献
936.
A kind of low surface energy fluorocarbon coatings from the synthesized fluoro-acrylic resin was developed.The molecule orientation principle of nonpolar and polar functional groups in the coatings was analyzed. The contact angles of pure water drops on the surfaces of various fluoro-monomer homopolymers and interpolymers were measured. The relation of coatings' fluoro-content with the surface energy was determined. The distribution of fluoric functional groups in the coatings was investigated. The test results show that though the total content of fluor of the fluorocarbon coatings is relative few, their surface energy is really low due to the enrichment of fluoro-chains on the surfaces. 相似文献
937.
电站油罐的防腐维护技术 总被引:1,自引:0,他引:1
介绍了油罐防腐施工中采用的新技术和新材料,这些先进的防腐工艺和手段有效地保护了油罐,预防了因腐蚀而产生的泄漏事故。 相似文献
938.
固体颗粒表面改性及其在推进剂领域中的应用研究 总被引:2,自引:0,他引:2
对推进剂组分中的氧化剂、燃料等固体颗粒进行表面改性处理,不仅能提高单组分的使用性能,也是提高推进剂力学性能、改善燃烧性能和推进剂工艺条件的重要途径.本文综述了固体颗粒表面改性的方法及表面改性后的表征,分析了包覆颗粒性能变化及其对推进剂性能的影响. 相似文献
939.
940.
以烧结镁砂为主要原料,分析讨论了复合结合剂、添加剂、纸纤维等对中间包镁质喷涂料性能的影响,研制的喷涂料性能优良,满足了武钢三炼钢厂60t中间包一个浇次生产需要。 相似文献