基体偏压对PEMFC不锈钢双极板Cr-N改性涂层性能的影响

目的 提高SS316L双极板的耐腐蚀性与导电性。方法 使用脉冲直流磁控溅射技术,改变基体负偏压,于SS316L双极板上制备了Cr-N薄膜。通过扫描电子显微镜、XRD衍射仪、电子探针分析仪对薄膜的成分和结构进行了检测分析。通过接触电阻测试、电化学腐蚀测试和接触角测试表征了薄膜的导电性、耐腐蚀性和疏水性。结果 薄膜的结构主要由Cr和Cr₂N组成,各组试样的成分相近。随着沉积过程中基体负偏压的增大,薄膜结构更加致密。镀膜试样的耐腐蚀性均好于基材SS316L,基体负偏压为400 V时,测得试样的腐蚀电流密度最低,为3.49×10^-7 A/cm²。镀膜试样的导电性均好于基材SS316L,基体为负偏压200 V时,双极板的导电性最好,表面接触电阻为8.02 mΩ·cm²。基体负偏压继续增大,双极板的接触电阻会有所下降。结论 随着沉积偏压的增加,薄膜中的N含量略有增加。薄膜沉积对SS316L双极板的导电性、耐腐蚀性和疏水性有明显的提高,较于基材自腐蚀电位提升了411 mV,腐蚀电流密度下降了2个数量级。沉积时较高...     

冷轧无取向硅钢表面麻面缺陷成因分析及其控制措施

针对某厂DMS森吉米尔轧机生产无取向硅钢表面麻面缺陷的问题,根据生产实际,对其形成原因从乳化液及工作辊两方面因素进行了分析。结果表明:乳化液对麻面缺陷的产生有一定影响,但不是主要因素,主要原因是由于二十辊森吉米尔轧机工作辊辊径较小,轧制相同长度带钢轧辊运转周期较大,容易产生疲劳失效而导致。为此,提出通过调整冷轧工序成品轧制道次的压下率以减小轧制力,从而减小工作辊的磨损疲劳;通过对轧制乳化液浓度、温度的合理控制,以改善润滑效果、提高轧制速度,而进一步缓解轧辊疲劳的改进措施,使该钢厂无取向硅钢麻面缺陷发生率由原来的18%降至0.8%,带钢表面质量明显改善。     

废汽油机发动机油的再生及其摩擦学性能研究

在减压蒸馏和白土吸附处理的基础上,对废汽油发动机油分别进行了溶剂精制、溶剂加表面活性剂助剂精制处理。在精制油中补充质量分数3%ZDDP添加剂后,利用UMT试验机和四球摩擦磨损试验机考察其抗磨减摩性能,采用扫描电子显微镜(SEM)和白光共焦三维形貌仪分析试验后试样磨痕表面形貌。结果表明:废油通过溶剂精制后得到的精制油,在补充3%的ZDDP后,具有良好的抗磨减摩性能,特别是采用溶剂加表面活性剂助剂精制处理后得到的精制油,补充ZDDP后抗磨减摩性能大大改善,甚至优于新油。     

水润滑轴承研究进展

在船舶的推进系统中,以水替代矿物油作为工作介质的水润滑轴承具有节能环保、结构简单、维修方便等优点,已成为各国竞相研究的热点.概述水润滑轴承的研究现状,包括理论研究、结构设计、材料研究等,并总结各种水润滑轴承材料的性能特点;介绍赛龙、飞龙、尼龙和超高分子量聚乙烯几种新型水润滑轴承材料的优缺点;分析水润滑轴承目前存在的主要问题以及需要进一步研究的重点和目标.     

Tribological properties of AlCoCrFeNiCu high-entropy alloy in hydrogen peroxide solution and in oil lubricant

Pin-on-disc tests to investigate the tribological behavior of AlCoCrFeNiCu high-entropy alloy under lubrication conditions with 90% hydrogen peroxide solution and lubricant oil, respectively, were performed. The study demonstrates that the AlCoCrFeNiCu high-entropy alloy lubricated correspondingly with lubricant of 90% hydrogen peroxide solution (hereafter termed hydrogen peroxide lubricant) and lubricant oil significantly improves its friction and wear-resistance properties. Results showed that the friction coefficient, after a grinding stage, of the rubbing pair was lower than that with normal lubricant oil. The AlCoCrFeNiCu alloy in the lubricant with 90% hydrogen peroxide solution and lubricant oil exhibits a high resistance to wear. Analysis of the worn surface revealed that the AlCoCrFeNiCu high-entropy alloy lubricated with the hydrogen peroxide lubricant exhibited signs of inhomogeneous polishing oxidation and abrasive wear, with the wear mechanism changing with sliding distance, while the rubbing pair in normal lubricant oil is mainly dominated by abrasive wear.     

Sliding friction induced atom diffusion in the deformation layer of 0.45% C steel rubbed against Tin alloy

Evolution of microstructure and compositions in worn surface and subsurface of 45 (0.45 mass% carbon) steel disc slid against tin-alloy-pin was analyzed by SEM, TEM and SIMS. The mechanical alloying layer and plastic deformation layer were formed in the sliding friction-induced deformation layer (SFIDL) of 45 steel. Ultra-refine and nano grains were detected in the worn surface layer. Elements of Sn, Cu and Sb, originated from the mating tin-alloy-pin, with diffusion depth of 35 μm, 11 μm and 4 μm, respectively, were detected in its SFIDL. Mechanisms accelerating atom diffusion in SFIDL were subsequently propounded.     

条形微裂纹对16MnR钢解理断裂韧性的影响

在常温下对热轧16MnR低合金钢缺口试样进行了不同预加载荷的正反弯曲试验,以在缺口前引入不同尺寸的条形微裂纹,然后通过高温回火消除残余应力和加工硬化,随后在—196℃下进行4点弯曲断裂试验,研究了条形微裂纹尺寸对缺口试样解理断裂韧性的影响。结果表明:当预载荷比(P₀/P_gy)小于0.861时,预载荷对解理断裂韧性影响较小;当预载荷比大于0.861后,条形缺陷在外加载荷作用下撕裂而形成的条形微裂纹,并且随预载荷比的增大条形微裂纹数量增多、尺寸增大、分布区域扩大,断裂载荷、断裂吸收功随预载荷比的增加而迅速下降;条形微裂纹所引起的局部高应力应变范围增大,使解理起裂源分布范围增大,也造成了缺口韧性参数P₁和W数值的分散。     

GC MS法测定人造革残留氯乙烯单体

建立了测定聚氯乙烯人造革中的残留氯乙烯的顶空气相色谱 质谱法(GC MS)。采用N,N 二甲基乙酰胺(DMA)溶解聚氯乙烯人造革样品,在70℃下平衡30 min,顶空进样进行气相色谱 质谱分析。结果显示,在0.2～20μg范围内,该方法线性关系良好,相关系数r=0.999。对样品进行3组不同浓度水平的加标测定(n=6),平均回收率为88%～92%,相对标准偏差(RSD)小于5.5%,检出限为0.2 mg/kg。该方法简便、快速,准确,可用于测定聚氯乙烯人造革中氯乙烯单体含量。     

Evolution of friction-induced microstructure of SUS 304 meta-stable austenitic stainless steel and its influence on wear behavior

The microstructure evolution of the worn surface and sub-surface layer of SUS 304 austenitic stainless steel (ASS) disc against Al₂O₃ ceramic ball were studied on the basis of the tribological behaviors in the tests performed using a Cameron-Plint TE67 pin-on-disc tester. The microstructure after friction test was observed by optical and scanning electron microscope. The possible phase transformation of meta-stable austenite to martensite was detected by X-ray diffractometer. Results showed that friction-induced deformation led to finer grain at the subsurface beneath the worn surface. Furthermore, white layer was observed on some worn surface layers after higher normal loads. Transformed martensite from the austenite appeared on the worn surface under both low and high normal-loading conditions. Absence of transformed martensite was detected at the site about 25 μm below the worn surface although the grains at the site were still intensive and fine. In addition, the specific wear rate of SUS 304 stainless steel specimens was measured, and the possible reasons affecting the wear behavior were analyzed and discussed.     

奥氏体不锈钢低温渗碳技术的研究现状及应用前景

奥氏体不锈钢是一种应用非常广泛的金属耐蚀材料,但强度较低,影响了它的使用寿命.长期以来,其表面强化与耐蚀性能之间的矛盾一直未能根本解决.本文综合评述了一种近年来发展较快的不影响奥氏体不锈钢耐蚀性能的表面强化工艺--奥氏体不锈钢低温渗碳技术,论述了该技术的工艺特点,探讨了该技术的强化原理,并预测了它的发展前景.