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101.
The transient state in the oxidation of binary alloys forming the most-stable oxide: A numerical solution 总被引:1,自引:0,他引:1
The initial transient high-temperature oxidation stage for binary alloys forming the most-stable oxide has been examined by means of a numerical procedure based on the finite-difference method. At variance with previous models, the present treatment takes into account the effect of the rate of the reaction at the scale/gas interface over the corrosion kinetics. The calculations concerning the transient stage are developed either using the general parabolic rate law to represent the overall scaling kinetics or using the rate law of the reaction at the scale/gas interface as a boundary condition without imposing any particular rate law to the overall process. A correct analysis of the oxidation behavior of binary alloys during the transient stage must take into account the kinetics effect of the rate of the surface reaction. The concentration of the most-reactive element at the alloy/scale interface changes regularly with time, decreasing gradually from the initial bulk value to its final steady-state value. The present results are in good agreement with those obtained by means of an approximate analytical model developed previously. 相似文献
102.
铝-锂合金腐蚀性能研究综述 总被引:3,自引:0,他引:3
综述了铝-锂合金孔蚀、晶间腐蚀、应力腐蚀断裂(SCC)及剥蚀的研究现状。阐述了加工状态、热处理、显徽组织及腐蚀介质对一些铝-锂合金孔蚀及晶间腐蚀行为与SCC敏感性的影响及其影响机制.同时报道了一些研究铝-锂合金剥蚀的新方法,并提出了进一步研究的方向. 相似文献
103.
Effect of HCl pre-treatment on corrosion resistance of cerium-based conversion coatings on magnesium and magnesium alloys 总被引:2,自引:0,他引:2
The corrosion protection afforded by a cerium conversion coating, formed by immersion in a solution containing rare earth salt and hydrogen peroxide, on pure magnesium and two magnesium alloys, AZ91 and AM50, has been studied. The effect of HCl pre-treatments on the morphology and on the corrosion resistance of the cerium conversion layer was investigated. A thicker and more homogeneous distribution of the conversion coating was obtained when the sample surface was pre-treated with acid. Higher amounts of cerium on the surface of the pre-treated samples were detected. The cerium conversion coating increased the corrosion resistance of the alloys because it ennobled the corrosion potential and decreased both the anodic and cathodic current. The acid pre-treatment further increased the corrosion resistance of the coated alloys. After five days of immersion in chloride environment the untreated samples showed localized corrosion while the chemical conversion coated samples appeared unaffected. 相似文献
104.
E.M.K. Hillier 《Corrosion Science》2004,46(3):715-727
Slow strain rate tests were performed on quenched and tempered AISI 4340 steel to measure the extent of hydrogen embrittlement caused by electroplating with zinc-cobalt alloys. The effects of bath composition and pH were studied and compared with results for electrodeposited cadmium and zinc-10%nickel. It was found that zinc-1%cobalt alloy coatings caused serious hydrogen embrittlement (EI 0.63); almost as severe as that of cadmium (EI 0.78). Baking cadmium plated steel for 24 h at 200 °C gave full recovery of mechanical properties but specimens plated with zinc-1%cobalt and then baked still failed in 89% of the time of unplated controls. It was shown that hydrogen uptake and embrittlement could be controlled by depositing thin layers of cobalt or nickel at the steel/coating interface. For example, the least embrittlement was caused by zinc-10%nickel (EI 0.037) due to a nickel rich layer with very low hydrogen diffusion coefficient that formed during the initial stages of electroplating. Similarly, a 0.5 μm nickel layer was effective in lowering the embrittlement caused by zinc-1%cobalt to that of zinc-10%nickel. Furthermore, a 0.5 μm cobalt layer deposited before a zinc-1%cobalt coating gave virtually 100% recovery of mechanical properties after baking. 相似文献
105.
106.
Research and Applications of Semi-solid Processing 总被引:1,自引:0,他引:1
Since it was pioneered by Flemings and otherresearchers [11, the semi-solid metal processingtechnique has been widely stUdied in the world.Especially in the past decade, SSM as a newproduct forming technique has been rapidly developed and put into commercial applications[2, 31. In recent years, with the development ofthe ado-industry of China, a lot of researchwork on SSM has been done, including the preparation of slumes, reheating and thixoforming[Al6]; moreover, great achievements have … 相似文献
107.
M.L. Zhang Y.D. Yan Z.Y. Hou L.A. Fan Z. Chen D.X. Tang 《Journal of Alloys and Compounds》2007,440(1-2):362-366
Mg–Li alloys have been prepared by electrolysis in a molten salt electrolyte of 50% LiCl–50% KCl (mass%) at low temperature of 420–510 °C. The effects of electrolytic temperature and cathodic current density on alloy formation rate and current efficiency were studied. For the deposition of metallic lithium on the cathode consisting of solid Mg and liquid Mg–Li, both electrolytic temperature and cathodic current density have no obvious influence on current efficiency; while for the deposition of metallic lithium on the solid magnesium cathode, both electrolytic temperature and cathodic current density greatly affect alloy formation rate and current efficiency. The optimum electrolysis condition is—molten salt mixture, LiCl:KCl = 1:1 (mass%), electrolytic temperature: 480 °C, cathode current density: 1.13 A cm−2. Mg–Li alloys with low lithium content (about 25 wt% Li) were prepared via electrolysis at low temperature following by thermal treatment at higher temperature. 相似文献
108.
109.
低熔点Cu-P基中间合金及其变质效果 总被引:3,自引:1,他引:3
利用差示扫描量热仪(DSC)、扫描电子显微镜(SEM)和金相显微镜等手段对Cu-P基中间合金进行了研究。结果表明,在二元共晶Cu-P中间合金中加入一定量的Sn可制成低熔点的Cu-16Sn-8P中间合金;在此基础上研制出一种熔点为630℃左右的低熔点的多元Cu-P基中间合金。与Cu-P中间合金相比,该低熔点多元Cu-P基中间合金对过共晶AI-24Si合金具有更好的变质效果。同时,该中间合金对ZL109合金也具有良好的变质效果。 相似文献
110.