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31.
Masahiko Ogura Norikazu Mizuochi Satoshi Yamasaki Hideyo Okushi 《Diamond and Related Materials》2005,14(11-12):2023
The deuterium (hydrogen) passivation effect on acceptors in boron-doped CVD homoepitaxial diamond was studied by electrical (Hall-effect) and secondary ion mass spectroscopy (SIMS) measurements. Deuterium was incorporated into the samples using microwave (MW) deuterium plasma at 673 K for 2–24 h. We observed the progress of acceptor passivation with p-type conduction, which finally resulted in a highly resistive state. 相似文献
32.
R. C. Pennefather D. H. Boone 《International Journal of Pressure Vessels and Piping》1996,66(1-3):351-358
Cyclic oxidation tests were performed on a large variety of commercially available overlay coatings. The results of cyclic oxidation tests confirmed that the composition of the coating as well as the processing method of the coating can affect the life of the system. Coating life was determined by the time to coating penetration and initiation of substrate attack. As this work was part of a effort to evaluate the relative protectiveness of available coating systems for Industrial Gas Turbine applications at relatively high temperature, an extensive testing programme was undertaken. The different coatings were tested to visual failure. The results presented in this paper concentrate on the surface instability of the coating. Apart from usual oxidation of the coating an additional degradation mechanism was observed. A mechanical effect caused by the instability of the coating as a result of the difference in the thermal coefficient of expansion and mechanical properties between the substrate and coating. This effect, the so-called “rumpling” effect, resulted in a significant reduction in time to penetration and was in some systems the life controlling factor. 相似文献
33.
高温润滑涂层设计的系统考虑 总被引:3,自引:0,他引:3
航天、航空、核能等尖端技术迫切要求使用耐高温润滑涂层,以保护金属构件的表面,增加发动机、推进器的工作效率和输出功率,80年代国际摩擦学界根据工业和国防的需要将高温润滑涂层和耐磨材料定为摩擦学学科发展的重要研究方向之一。本文对高温润滑涂层设计中遇到的典型环境、涉及到的关键问题、未来发展的途径等问题作了阐述。 相似文献
34.
Advanced high-energy plasma systems are being used to achieve the benefits of the high-velocity oxy-fuel (HVOF) system without
losing the inherent advantages of plasma for coating of gas turbine parts. MCrAlY coatings play a very important role in the
performance and reliability of gas turbine components. One of the important considerations for next generation of gas turbines,
which have more demanding conditions and need to withstand ever increasing operating temperatures, is that they should possess
very low oxygen content levels in the coating. Low oxygen content coatings are applied by the expensive low-pressure plasma
spray (LPPS)/vacuum plasma spray (VPS) technique for critical components in aero- and land-based gas turbines. This work deals
with the development of low-cost LPPS equivalent coatings (having low oxygen content) using the high-energy high-velocity
plasma spray (HEHVPS) gun and inert gas shroud. A comparison has also been made with CoNiCrAlY coatings by HVOF. 相似文献
35.
36.
The role of adhesion promoters, copper oxidation, and thermal aging in the adhesion mechanism of enamel on copper winding wires is investigated. Evidence is presented on the predominant role of the copper oxide at the interface in the wire–enamel adhesion phenomena. The oxidation process and the copper oxides stability at the interface are seen to strongly depend upon the thermal aging of the wire and the nature of both the enamel and the promoter. Atomic force and scanning electron microscopy analyses show that so‐called promoters act more efficiently as corrosion inhibitors than as adhesion enhancers. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 952–958, 2003 相似文献
37.
Theoretical predictions using a modified radical species ternary diagram for C–H–O system indicate that addition of sulfur expands the C–H–O gas phase compositional window for diamond deposition. Sulfur addition to no-growth domain increases the carbon super-saturation by binding the oxygen and the addition of sulfur to the non-diamond domain reduces the heavy carbon super-saturation by decreasing CnHm species concentration in the gas phase. The overall effect of sulfur addition to gas phase mixtures is characterized as that of oxygen addition to the C–H system, i.e. expansion of the compositional window over which diamond can be deposited from the gas phase. In addition, the increasing sulfur concentration to diamond domain feed gases beyond 2000 ppm did not affect the steady state gas phase composition but the quality of diamond was reduced. 相似文献
38.
A theoretical model is presented to describe the effect of ion beam bombardment rate on the formation of tetrahedral amorphous carbon (ta-C) films. The critical ion energy, Ec, corresponding to a 50% sp3 content in the films, is found to be dependent on both the effective thermal resistance and the ion beam bombardment rate. In the model, the ‘window’ width in the ion energy scale for the formation of ta-C material increases with decreasing deposition rate and with a reduction in the effective thermal resistance, until limited by lower and upper boundary thresholds. Experimental data are reproduced by the model. The plasmon energy, which correlates with sp3 fraction, is found experimentally of be higher for lower deposition rate and smaller effective thermal resistance. Data points for high sp3 content ta-C films deposited on silicon substrates at room temperature occupy a region in the ion energy-deposition rate (E-r) diagram similar to that predicated from the theory. 相似文献
39.
Statistical studies of branched ester latex and paint properties 总被引:3,自引:0,他引:3
R. A. Prior W. R. Hinson O. W. Smith D. R. Bassett 《Progress in Organic Coatings》1996,29(1-4):209-224
Vinyl versatate, butyl acrylate and 2-ethylhexyl acrylate were compared as comonomer, for colloid-stabilized vinyl acetate latex polymers to assess their impact on latex coating properties. Vinyl versatate afforded advantages in scrub resistance, gloss, hydrophobicity and higher glass transition temperatures. Butyl acrylate developed better wet adhesion efficiency, gel content and hiding efficiency. 2-Ethylhexyl acrylate offered performance comparable to butyl acrylate in hiding efficiency, lowering copolymer glass transition temperatures, and gloss development. Combinations of these monomers, in many instances, afforded a better balance of performance properties than individual monomers alone. In the subject study, a simplex-centroid design was utilized to statistically map polymer compositions for determining the effect of comonomer composition on latex and paint film properties. In addition to developing contour maps of polymer and paint properties as a function of composition, a technique for studying structure-property relationships is presented. 相似文献
40.
Coatings derived from organofunctional silanes have been investigated as possible replacements for the chromate-based systems used in the aerospace industry. In this study, organofunctional silanes [bis-(triethoxysilylpropyl)ethane and bis(triethoxysilylpropyl) tetrasulfide] were reacted with commercially available acrylate (ECO-CRYL™ 9790) and epoxy (EPI-REZ™ WD-510) resins, resulting in a one-step, low-VOC, chromate-free primer. Liquid-state 29Si and 13C NMR were used to determine structural characteristics of various optimized formulations. 相似文献