机械研磨电镀锌-铁合金镀层及其耐蚀性的研究

在电镀锌-铁合金镀层的过程中施加机械研磨作用,制得机械研磨电镀锌-铁合金镀层。采用扫描电子显微镜观察了镀层的微观形貌,并采用电化学试验研究了镀层在3.5%的NaCl溶液中的腐蚀行为。结果表明:与普通锌-铁合金镀层相比,机械研磨电镀锌-铁合金镀层的组织结构致密,晶粒达到了纳米晶尺寸,耐蚀性更好。     

稀土铈对热浸镀锌层耐蚀性能的影响

在锌浴中分别添加不同质量分数(0.00%~0.12%)的稀土Ce,获得了热浸镀Zn–Ce镀层。采用扫描电镜观察不同镀层的截面形貌,通过中性盐雾试验和测量电化学极化曲线及电化学阻抗谱,研究了Ce对锌镀层耐蚀性的影响。结果表明,稀土Ce对镀层结构无影响,但可在一定程度上控制Zn–Ce镀层的超厚生长。与纯锌镀层相比,Zn–Ce镀层经中性盐雾试验8 h后的白锈面积较小,且出现红锈的时间也延后,在5%NaCl溶液中的自腐蚀电位更正,电化学阻抗也更高。因此锌浴中Ce的添加可提高镀层耐蚀性。Ce的添加量为0.08%时,Zn–Ce镀层的耐蚀性最佳。     

稀土元素对桥梁缆索用热浸镀Zn-10Al镀层钢丝耐蚀性能的影响

通过双镀法制备Zn-10Al-xRE(x=0.05,0.08,0.11,0.14,0.17)五种热浸镀锌铝镀层,并利用中性加速盐雾试验、电化学实验及扫描电子显微镜（SEM）分析其腐蚀形貌及耐蚀性能。结果表明,五种镀层在中性加速盐雾试验下,可保证基体在120d以内不被腐蚀,而纯锌镀层在30d时已经出现红锈,证明Zn-10Al-xRE的耐蚀性能可达到纯锌镀层4～5倍。Zn-10Al-xRE镀层钢丝的耐蚀性能随稀土含量的上升先升高再降低,添加0.08%RE的Zn-10Al镀层耐蚀性最好。用SEM对120d盐雾试验下的镀层钢丝进行观察,可以看出纯锌镀层的腐蚀产物较为疏松,Zn-10Al-xRE的腐蚀产物较为致密,Zn-10Al-xRE中腐蚀产物大约分为韧窝状、球状及针片状,耐蚀性能最好的Zn-10Al-0.08RE镀层中含有大量韧窝状腐蚀产物。     

镁合金化学镀Ni-P合金和脉冲电镀Zn-Ni合金组合镀层

在镁合金表面制备了化学镀镍-磷合金和脉冲电镀锌-镍合金组合镀层。采用扫描电镜、能谱仪考察了镁合金化学镀N i-P合金和电镀锌-镍合金组合镀层的形貌和成分。结果表明,组合镀层表面均匀、致密、无明显缺陷。采用电化学测试系统对组合镀层进行了动电位扫描极化曲线测试。研究了镀层腐蚀后的表面形貌和成分。结果表明,在腐蚀介质中,电镀锌-镍合金层首先发生腐蚀,之后发生化学镀镍层的腐蚀,电镀锌-镍合金层不仅对化学镀镍底层的腐蚀起到机械保护作用,还作为牺牲阳极起到电化学保护作用,因此延缓了腐蚀介质对镁合金基体的腐蚀。     

影响湿法超声机械镀锌层性能的因素

湿法超声机械镀是一种基于超声加工的特种加工方法,该方法利用超声频电振荡信号产生的机械振动进行机械镀,可获得优良的镀层,镀层的耐腐蚀性较好。为了探究影响湿法超声机械镀镀锌层性能的因素,从锌粉粒径、冲击介质以及强化时间三因素进行实验研究。结果表明,随着锌粉粒径的减小,镀锌层的致密性、耐腐蚀性显著增加;随着玻璃珠尺寸的减小,镀锌层表面的粗糙度降低,致密性比较好;随着强化时间的增加,镀层表面质量提高,耐腐蚀性好。     

超声振动对机械镀锌层的性能影响

分别采用机械镀和湿法超声机械镀的方法获得两种机械镀锌层。用扫描电子显微镜及其配备的能谱仪分析了镀层的表面形貌、断面形貌和镀层的组成,并分别用贴滤纸法和划格试验分别对镀层的孔隙率和结合力进行表征,采用表面硬度计测量了镀层的硬度,利用中性盐雾试验测试了镀层的耐腐蚀性能。结果表明,与机械镀锌层相比,湿法超声机械镀锌层表面质量明显改善,相同厚度的湿法超声机械镀锌层的耐腐蚀性能优于机械镀锌层,是一种综合性能优良的防护镀层。     

氯化钾镀锌层耐盐雾性的研究

氯化钾镀锌广泛应用于装饰与防护 ,锌镀层白亮 ,经染色后既能保持金属光泽 ,又具有鲜艳色彩 ,显著提高了镀层装饰性。镀锌层与其它涂料可联合使用 ,使镀层防腐性明显提高。虽然 ,镀锌层不经常作最终耐蚀层 ,但在进行其它涂复前 ,保持镀锌层不腐蚀 ,是很重要的 ,而且镀层本身的耐蚀性、结合力等对最终产品的耐蚀性、结合力也有重要影响。1　腐蚀机理与铜、铁金属相比 ,锌的电极电位较负 ,比较活泼 ,用于铜、铁金属的防护性镀层 ,锌是阳极。在有腐蚀介质存在时 ,锌为阳极 ,既能与酸反应又能与碱反应 ,优先被腐蚀 ,基体金属受到了保护。2　影响…     

机械镀锌-镍合金工艺的研究

在机械镀锌、锌-铝工艺的基础上,通过调整活化剂和促进剂的种类及用量,研制开发了机械镀锌-镍合金工艺.利用该工艺在钢基表面上得到了不同配比的锌-镍以及锌-铝-镍合金镀层.对这些镀层进行5%NaCl溶液喷雾加速腐蚀试验以及全浸加速腐蚀试验,并与机械镀锌层进行对比.结果表明,各种配比的锌-镍合金镀层的耐蚀性能皆好于机械镀锌层,并且随着镍含量的增加而提高;锌-铝-镍合金镀层的耐蚀性能比镀锌层提高7倍左右.     

纳米复合镀层增强汽车油嘴表面防护效果的研究

观察了镀锌汽车油嘴和镀纳米复合镀层汽车油嘴的表面形貌,并分别测定了两者在体积分数为10%的盐酸溶液和体积分数为20%的硫酸溶液中的腐蚀质量损失率,对比了镀锌层和纳米复合镀层对汽车油嘴表面的防护效果。结果表明:纳米复合镀层表面的腐蚀程度较轻,腐蚀质量损失率较低。平整的形貌和致密的结构,赋予纳米复合镀层更好的耐蚀性,因而其对汽车油嘴表面的防护效果优于镀锌层的。     

电流密度对无氰镀银层性能的影响

本实验采用硫代硫酸盐体系的镀银液,利用电沉积法在紫铜上制备银层。通过扫描电镜(SEM)、X射线衍射仪(XRD)、电化学工作站、抗硫实验、抗老化实验对镀层微观形貌、晶面取向、晶粒大小、耐蚀性、抗硫性、抗老化性能进行测试。结果表明,当电流密度为0.4 mA·cm-2时,镀层结晶最致密,表面最平整,孔隙率最小,晶面取向为(111),自腐蚀电流密度为70.17 mA·cm-2,自腐蚀电位为-0.2901 V,抗硫性及抗老化性能最优。     

锌粉对环氧树脂防腐涂层改性的研究

通过添加纳米锌粉研究环氧富锌防腐涂层的工艺性能,分析了腐蚀电化学行为、涂层附着力及耐腐蚀性能.结果表明纳米锌粉的加入对涂层防腐性能有显著影响,随着纳米锌粉含量的增加,环氧富锌涂层的电化学性能明显提升,电阻值增加2～3个数量级,当纳米锌粉的加入量为20％时,涂层的防腐性能最佳.     

Optimization of phosphate coating properties on steel sheet for superior paint performance

The adhesion of electrodeposition (ED) paint on steel sheets for automobiles is highly influenced by the properties of the zinc phosphate coating which is used to improve its corrosion resistance. In the present study, a steel surface was pretreated with two types of zinc phosphate formulations followed by ED painting. The surface morphology, crystal plane, and porosity properties of phosphate coating on steel samples were studied by scanning electron microscope, X-ray diffraction, and electron probe microanalyzer, respectively. The corrosion resistance of painted samples was evaluated by an accelerated corrosion test as well as by electrochemical techniques like cathodic disbonding and AC?CDC?CAC tests. The phosphate coating enriched with a phosphophyllite structure showed small globular crystals with less porosity, whereas a hopeite structure showed coarse crystals with high porosity and comparatively thicker coating. The maximum corrosion resistance was observed in the painted sample, where the phosphate coating comprised a phosphophyllite structure. On the other hand, the painted samples phosphated with a predominantly hopeite structure showed inferior corrosion resistance performance. The unphosphated sample showed severe degradation in paint adhesion and corrosion resistance, which substantiates the importance of phosphate pretreatment.     

镀锌层表面电沉积防腐蚀膜层工艺

为了提高镀锌层的耐蚀性,通过施加电压的方式,促进成膜反应的进行,在镀锌层表面制备一种耐腐蚀膜层。采用电化学工作站及中性盐雾试验测试该膜层的耐蚀性,初步确定了一种较优工艺。结果表明:经处理的镀锌层的耐蚀性较未经处理的镀锌层的耐蚀性有很大的提高。该工艺简单,并且对环境无污染。     

Corrosion resistance of phosphate coatings obtained by cathodic electrochemical treatment: Role of anode–graphite versus steel

The formation of phosphate coatings by cathodic electrochemical treatment using graphite and steel anodes and evaluation of their corrosion resistance is addressed in this paper. The type of anode used, graphite/steel, has an obvious influence on the composition of the coating, resulting in zinc–zinc phosphate composite coating with graphite anode and zinc–iron alloy–zinc phosphate–zinc–iron phosphate composite coating with steel anode. The corrosion resistance of the coating is found to be a function of the composition of the coating. The deposition of zinc/zinc–iron alloy along with the zinc phosphate/zinc and zinc–iron phosphate using graphite/steel anodes has caused a cathodic shift in the E_corr compared to uncoated mild steel substrates. The i_corr values of these coatings is very high. EIS studies reveal that zinc/zinc–iron alloy dissolution is the predominant reaction during the initial stages of immersion. Subsequently, the formation of zinc and iron corrosion products imparts resistance to the charge transfer process and increases the corrosion resistance with increase in immersion time. The corrosion products formed might consist of oxides and hydroxychlorides of zinc and iron. The study suggests that cathodic electrochemical treatment could be effectively utilized to impart the desirable characteristics of the coating by choosing appropriate anode materials, bath composition and operating conditions.     

钛和铈对热浸锌镀层组织与耐蚀性能的影响

为了获得厚度适中、耐蚀性能好的热浸镀锌层,在锌浴中添加微量的Ti和Ce,分别在Zn-0.04%Ti、Zn-0.02%Ce和Zn-0.04%Ti-0.02%Ce镀浴中制得热浸锌合金镀层.采用金相显微分析以及电化学阻抗谱、电化学极化测试、中性盐雾试验,研究了Ti和Ce对镀层组织和耐蚀性能的影响.结果表明:在锌浴中添加0.0...     

铈对镁合金微弧氧化膜微观结构和耐蚀性的影响

利用扫描电镜、电化学工作站等,研究了不同铈盐添加方法对ZE10镁合金在由硅酸钠14 g/L、氟化钠14g/L、氢氧化钠2 g/L、甘油5mL/L组成的溶液中,于电压300 V、脉冲频率1 kHz、占空比15％的条件下微弧氧化20 min所得微弧氧化膜厚度、形貌和耐蚀性的影响.结果表明,先进行铈盐转化处理再微弧氧化和在电...     

镀锌层单宁酸钝化膜的耐蚀性

为提高镀锌层的耐蚀性,以氟钛酸钾、双氧水、硝酸为辅助成分,制备了单宁酸钝化液,并对低碳钢上的碱性镀锌层进行了钝化处理.通过质量分数为5%的NaCl溶液浸泡试验,确定了最佳钝化液组成和钝化工艺条件为:单宁酸40 g/L,HNO3 5 mL/L,氟钛酸钾10g/L,H2O2 60 mL/L,温度25℃,时间20～30 s....     

Improvement of corrosion resistance of magnesium metal by rare earth elements

Mg metal containing rare earth metals (REs) can be electrowon directly by molten salt electrolysis. The clarification of the optimum RE content in Mg is necessary to fix the electrolytic conditions in the direct electrowinning of Mg with RE. From this point of view, effect of RE addition in Mg metal on its corrosion property was studied in detail in this study. The specimen was prepared by adding La, Nd, or Ce in melted Mg metal, and its corrosion resistance was examined by an immersion test in 3 mass%-NaCl solution at room temperature. The corrosion resistance of Mg was improved greatly by adding a small amount of RE, whereas the excess addition of RE deteriorated the corrosion resistance. The optimum RE content was about 0.5 mass%. In this study, the corrosion property of Mg with an artificial surface oxide layer was also studied to clarify the effect of surface oxide. The corrosion resistance of Mg was particularly strengthened by conversion coating in a solution including La(NO₃)₃, Nd(NO₃)₃, or Ce(NO₃)₃, with Mg(NO₃)₂. This result suggests that the surface oxide film consisting of both Mg and RE gives ideal corrosion resistance to Mg metal. Mg metal with conversion coating including RE should also be of use as a corrosion-resistant material.     

Zn-5%Al-RE镀层耐蚀性能的研究

试验了在高碳钢丝表面上热浸镀Zn-5%Al-RE合金层。通过湿热试验、晶间腐蚀试验、盐雾腐蚀试验，研究了该合金镀层的耐蚀性能，并与镀锌钢丝的耐蚀性能进行了对比。在水蒸汽的晶间腐蚀试验表明，合金镀层还略逊于锌镀层，但是在采用模拟海水的湿热试验以及盐雾腐蚀试验中，合金热浸镀层的耐蚀性能明显优于普通锌镀层，阳极极化曲线表明，合金层的致钝电流密度小，致钝电位较低，且稳定钝化区较宽，这可能是合金热浸镀层在海水中具有较好耐蚀性能的主要原因。     

A novel approach to heal the sol-gel coating system on magnesium alloy for corrosion protection

Sol-gel-based coatings exhibit high potentiality to be as an alternative to toxic chromate coatings for surface pre-treatment of metals and alloys. However, as soon as even small defects appear in the coating, the coating cannot stop the development of corrosion process. Present work demonstrates the possibility to use zinc nitrate as healing agent to repair the organic silane coatings in NaCl solution. The zinc nitrate was added to the 0.005 M NaCl solution where AZ91D magnesium alloy coated with organic silane coating was immersed. The healing process and the healing mechanism were investigated by electrochemical measurements and scanning electron microcopy coupled with energy dispersive spectroscopy. The results demonstrated the introduction of zinc nitrate to the electrolyte could stop the development of corrosion process of the coating system and a remarkable recovery on corrosion resistance could be obtained. This effect may be attributed to the formation of zinc oxide/hydroxide on the defective areas, hindering the corrosion activities.