划痕法测Ni—P合金镀层结合力的研究

本文用划痕法测定了Ni-P合金镀层的结合力;观察了划痕侧面镀层的失效形式;分析了三种评定结合力的参数。结果指出,临界载荷L_C、平均应力σ_A用于评定Ni-P镀层的结合力是有条件的,而B-W公式存在的问题更多。     

An extension of Wagner's analysis of competing scale formation

Wagner's criterion to predict the minimum concentration of solute (N _B(min) ⁰ )necessary for the exclusive formation of its scale has been modified to incorporate both thermodynamic and kinetics requirements. The analysis presented here involves a receding alloy/scale interface for which the composition of the alloy at this interface is governed by thermodynamic equilibrium between the two competing scale phases and the base alloy. This is a more rigorous analysis than that of Wagner's, who assumed the alloy/scale interface to be immobile and the solute composition at the interface to be zero. A comparison is made between values of N _B(min) ⁰ found experimentally and those predicted by Wagner's and the present criterion for a number of alloy-gas systems. It is shown that the criterion developed in the present analysis can often provide a better approximation of the actual N _B(min) ⁰ .The expressions derived from the present analysis have been extended also in a semiquantitative manner to provide a criterion for the minimum amount of solute in the alloy required for the transition from internal to external scale formation.     

High-temperature sulfidation of Fe-30Mo alloys containing ternary additions of Al

Fe-30Mo alloys containing up to 9.1 wt% Al were sulfidized at 0.01 atm sulfur vapor over the temperature range of 700–900°C. The sulfidation kinetics followed the parabolic rate law for all alloys at all temperatures. For alloys containing small and intermediate amounts of Al (<4.8 wt.%), a duplex sulfide scale formed. The outer layers of the scales were found to be relatively compact FeS in all cases; whereas the inner layers were composed of the layered compound MoS ₂ (intercalated with iron), the Chevrel compound Fe _x Mo ₆ S ₈,a spinel double sulfide Al _x Mo ₂ S ₄,depending on the Al content of the alloy and the sulfidation temperature. Extremely thin scales were found on the alloys with higher Al contents. Accordingly, extremely slow sulfidation rates were observed—even slower than the sulfidation rate of pure Mo. The transition of the sulfidation kinetics from a high-rate active mode to a low-rate passive mode requires both a critical Al content in the alloy and a critical Mo content. Because of the two-phase nature of the alloys, the latter requirement implies a critical volume fraction of the intermetallic second-phase in the alloy, which has been known as the multiphase effect. Interestingly, the multiphase effect in these alloys was also a function of the Al content in the alloys.     

球磨对ZrO2（Y2O3）超细粉末性能的影响

以共沉淀法制备煅烧态ＺｒＯ２（Ｙ２Ｏ３）超细粉末为研究对象，研究了球磨对其物理和烧结性能的影响，结果表明，球磨虽可以有效地减小粉末的团聚尺寸，但对粉末一次颗粒尺寸的的影响不大，球磨可以显著增加团聚程度较严重的锻烧态粉末的比表面积，但对团聚程度较轻的粉末，其影响大：球磨还可显著减小粉末的晶粒尺寸，这与粉末在球磨过程中发生了相变有关。此外，对团聚较严重的粉末，球磨可改善其烧结性能，但对团聚程度较轻的粉     

稀盐酸中锰结核还原浸出溶液净化除铁

针对酸性氯化物中黄铁矿还原浸出锰结核的溶液成分特点，选择黄钠铁矾法进行了沉淀分离铁的研究。结果表明温度和晶种以及溶液ｐＨ值是影响铁矾沉淀的重要因素。在ｐＨ２．０左右，溶液温度高于９０℃，足量晶种加入的情形下，１５０ｍｉｎ后可将溶液中的铁含量降至０．１ｇ／Ｌ。沉矾过程的表观活化能为９４．６６ｋＪ／ｍｏｌ。黄铁矿氧化生成的硫酸根随铁一同沉淀，从而消除了ＳＯ２－４在氯化物体系中的积累。     

数控小孔冲床网眼平板加工中的波浪纹缺陷成因分析及排除

文章就数控小孔冲床加工纺织烘干设备中帘子网眼平板产生波浪纹缺陷的原因,进行了全面、详细的理论分析.在排除机床、模具精度影响的基础上,针对压料机构运动误差产生的机理和不利影响,详细分析了网眼冲孔加工产生波浪纹缺陷的根本原因,提出了相应的改进措施,在实践中具有良好的实用效果.     

Si及变质处理对Mg2Si/Mg复合材料的影响

分析了Mg-Si二元合金直接原位形成Mg2Si/Mg复合材料的过程,研究了Si含量以及变质处理对复合材料组织和性能的影响。试验结果表明,随着合金中Si含量的增加,合金的流动性降低,复合材料中原位Mg2Si的数量增多,树枝晶形态更为发达;对优化的Mg-8Si合金,进行混合稀土(MM)和Sb变质处理,可明显改善Mg2Si的形态和分布,但Sb变质的效果要好于MM。合金经质量分数为1.2%的Sb变质处理后,Mg2Si以颗粒状均匀分布在Mg基体中,从而使复合材料具有较好的耐磨性。     

表面技术用新型加热与干燥设备

夜面涂装加热与干燥设备是近年来开发的节电新技术,可较传统热风炉或一般远红外炉节电15～40%,炉内上下温差3～8℃。文章提出用系统优化的原理和方法对乳白石英管低温辐射加热进行研究,设计中采用辐射密度分布法和部份功率控制法。     

Internally humidified polymer electrolyte fuel cells using water absorbing sponge

Polymer electrolyte fuel cell (PEFC) mounted with two strips of polyvinyl alcohol (PVA) sponge is presented and the effect of operating conditions on the cell performance is investigated. Mounting the sponge wicks is advantageous for the humidification of dry inlet air and for the removal of liquid water in the cell. It was found that dry inlet hydrogen could be internally humidified by water diffusion from the cathode to anode when operating in a counterflow mode. The results show that the relative humidity of the inlet gases could have little effect on the performance of the cell mounted with two sponge wicks under certain operating conditions. At a cell potential of 0.5 V, the current densities of the sponge-mounted PEFC operated with dry air are 5% and 31% higher than those of the conventional one without wicks operated with saturated and dry air, respectively. The molar percentage of water vapor to total water exiting the cathode (R_gas) is an important parameter to gauge the cell performance with dry gases. A very large R_gas may cause the membrane dehydration and subsequently a low cell performance.     

高掺量粉煤灰路面试验研究获得成功

据悉，“十一五”期间六盘水市的煤产量将达到4000万t／年，火电装机容量为1000万KW，粉煤灰排放量将逐步增到1000万t左右。为提高粉煤灰的综合利用率，拟将粉煤灰混凝土用于公路路面工程。