Preparation of electroless Ni–P composite coatings containing nano-scattered alumina in presence of polymeric surfactant

Ni–P electroless coating was applied on low carbon steel with the incorporation of different amounts of nano Al2O3 powder (ranging from 3 g/l to 30 g/l) in electroless bath. Corrosion properties and microstructures of the coating were studied. The dispersion stability of alumina colloidal particles stabilized by polymeric (non-ionic) surfactants in an electroless bath was also investigated. The surface morphology and the relevant structure were evaluated by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Corrosion behavior of the coated steel was evaluated by electrochemical impedance spectroscopy (EIS) and polarization techniques. The results showed that increasing alumina concentration not only changed the surface morphology, but also promoted the corrosion resistance. Addition of surfactants has an indirect effect on the amount of the incorporated particles. Meanwhile, in the presence of surfactant, corrosion resistance of Ni–P coating containing even a small quantity of alumina was improved since a stabilized bath was obtained.     

镀锌层三价铬常温黑钝工艺

本工艺对以三价铬为主成膜剂,添加辅助成膜剂(钴盐),发黑剂(镍、铁盐),活化剂进行常温黑色钝化工艺。通过一系列的正交实验讨论基础液的成分及工艺条件对钝化效果的影响,得出最佳的黑色钝化的工艺,实验结果得到黑色光亮的成品,中性盐雾实验超过72小时,满足工业生产的工艺要求。     

A STUDY ON THE SELECTED FACTORS AFFECTING CONCRETE PERMEABILITY

The effect of w/c ratio,incorporation of silica fume and maximum aggregate sizes on permeabilityof concrete were studied.The test results both from chloride permeability and water absorptionshowed that the permeability of concrete increased as the w/c increases whilst a limitedamount of replacement of cement with silica fume the permeability decreased significantly.Themaximum aggregate size in the range of 8 to 25 mm seems also affect permeability but with a muchless significant level. A linear relationship between chloride permeability and capillary absorptionwas found.     

无机缓蚀剂与表面活性剂对碳钢的协同缓蚀作用

采用动电势扫描法测定了碳钢在饱和 (NH4 ) 2 CO3溶液中的阳极极化曲线 ,研究了几种无机缓蚀剂的缓蚀作用及与表面活性剂复配后的协同效应。结果表明 :当体系中添加 0 .1%的量 ,钼酸钠缓蚀性能最好 ,相对缓蚀效率达 6 8.3% ;当 0 .0 5 %的钨酸钠与 0 .0 5 %平平加复配 ,协同缓蚀效率可达 72 .7% ;应用动电势扫描法能够快速、简便地测定腐蚀速率和评选缓蚀剂。     

化学镀Ni-P合金的工艺条件研究

采用单因素试验法和正交试验法研究了还原荆以及化学镀时间、温度、pH值对化学镀沉积速度的影响,得到了一种稳定性好、镀速快的化学镀Ni—P合金的工艺.其最佳工艺条件为:NiSO4·6H2O30g/L,NaH2PO2·H2O40g/L,柠檬酸钠10g/L,醋酸9mL/L,乳酸9mL/L,pH值6.0,施镀温度90℃,施镀时间1.5h.该工艺条件下,镀速可达11.14mg/(cm2·h),化学镀1.5h后镀层厚度可达23.6-24.0μm.镀层具有较强的耐蚀性,孔隙率分布较窄.镀层表面平整、光亮、分布均匀,有可视性很好的淡黄色的光泽,无麻点、裂纹、起泡、分层或结瘤等缺馅.     

化学沉积Ni-Mo-P合金镀层的组织与性能

对化学沉积Ni P和Ni Mo P合金的表面形貌及性能进行了比较分析 ,结果表明化学沉积Ni Mo P合金由于钼元素的加入 ,影响了镀层的组织结构 ,使Ni Mo P合金组织较Ni P的更为细小 ;具有比Ni P合金更为优异的耐蚀性和硬度 ;热处理时 ,延缓了晶化温度 ,在同一高温下具有比Ni P更好的耐蚀性。     

用CCD监测护环锻件S·C·C裂纹的试验研究

本文提出一种 CCD 光电传感器监测护环锻件 S·C·C 裂纹的新方法,它能早期发现裂纹的产生,准确显示裂纹的大小;为逐步实现汽轮发电机护环 S·C·C 的实时监测积累了经验.     

阳离子表面活性剂对铝在盐酸介质中的缓蚀作用

本文采用失重法和电化学方法研究了溴代十六烷基吡淀(CPB)对铝在盐酸介质中的缓蚀行为以及缓蚀剂浓度和温度对腐蚀动力学的影响,同时对此种阳离子表面活性剂的缓蚀机理进行了讨论。     

化学镀Ni-P合金性能的影响因素研究

本文从镀液配方、施镀温度以及镀层的后处理温度等方面考虑,研究它们在一定范围内的取值,及对镀层的硬度、摩擦磨损性能、耐蚀性的影响.试验结果证实影响甚微.这样,由于这些工艺条件的适当放宽,将会降低生产成本并给实际工作提供了方便.     

NiCrBSi激光熔敷层组织及腐蚀磨损行为

应用５ｋｗ—ＣＯ２激光器在４５钢基材上进行镍基合金激光熔敷处理．观察并测定了激光熔敷层的组织及显微硬度分布，着重探讨了该合金激光熔敷层在不同条件下的腐蚀磨损行为．试验结果表明，在酸性介质中，激光溶敷层的腐蚀磨损速率随介质浓度及冲击速度的提高而线性增加，其中冲击速度影响较为显著．激光熔敷层的腐蚀磨损失效是以磨料磨损为主，失效机制是显微切削并伴随着凿削磨损。