镁合金硫酸镍体系化学镀镍工艺及镀层性能研究

采用酸性钼酸盐酸洗、碱性钼酸盐活化工艺,研究了AM60镁合金上硫酸镍溶液体系化学镀镍的方法.采用扫描电子显微镜(SEM)观察镀层表面形貌,电子探针(EDX)分析镀层成分,电化学方法研究镀层腐蚀性能,锉刀试验测试镀层与基体结合力.结果表明,所得镀层为Ni-P合金镀层,磷质量分数为10%～14%;镀层均匀致密,无明显缺陷;镀层的自腐蚀电位接近-0.4 V(vs SCE),阳极极化曲线有明显的钝化区;Ni-P镀层耐蚀性好,与基体结合牢固.     

镁合金化学镀镍原理与工艺的研究进展

综述了镁合金化学镀镍工艺中镀前处理、化学镀镍、后处理等工艺及研究现状,介绍了各步工艺处理液配方和应用范围,提出了改进镁合金镀层质量的研究方向.     

AZ91D镁合金直接化学镀镍工艺

为了降低生产成本,研究了AZ91D镁合金直接化学镀镍工艺.借助表面分析技术分析了AZ91D镁合金化学镀镍前处理及直接化学镀镍后的表面形貌,研究了不同工艺条件对镀层表面形貌的影响,测试了镀层与基体的结合情况及镀层结构.结果表明:以硫酸镍为主盐,pH值为5.5～6.5,施镀温度为80～95℃,施镀时间为1.0～2.5h时,可在镁合金表面直接化学沉积一层表面平整、组织致密、与基体结合力良好及硬度较高的非晶态Ni-P合金镀层.     

环保型镁合金化学镀镍工艺研究

研究了镁合金的环保型化学镀镍工艺,对前处理工艺进行了简化,对镀液的稳定性、循环使用后的节约成本核算以及废液的回收处理等进行了研究和探讨.结果表明,使用一步前处理工艺能简化镁合金前处理工艺,提高镀镍层的结合强度和质量,且处理液中不含Cr6 、HF等对环境和人体有害的物质;化学镀液的循环使用可以大幅度节约生产成本,减少废液排放,提高资源的利用率.     

镁合金化学镀镍

镁合金在工业中的应用越来越广泛,通过化学镀镍可以克服镁合金耐蚀性和耐磨性差的缺点.介绍了镁及镁合金化学镀镍的原理/工艺的发展过程及研究现状,在此基础上指出了目前存在的问题和将来的发展方向.     

AZ91镁合金直接化学镀镍及镀层性能

为提高AZ91镁合金的耐腐蚀性能,优选了AZ91镁合金表面直接化学镀镍工艺,并对镀镍层的致密性、硬度、耐蚀性及结合力等进行了测定。获得了最佳工艺条件：5g／LNi（CH3COO）：,12mL／L40％HF,5g／Lc6H807·H20,30g／L25％NH3·H20,20g／LNa2HP04·H20,1mg／L硫脲,p...     

镁合金化学镀镍研究

研究了AZ91D镁合金化学镀镍工艺过程，操作条件，分析了镀层组织与成分，测定了镀层的厚度，显微硬度，镀层具有较好的结合力和耐蚀性。     

镁合金磷化处理对化学镀镍层性能的影响

为了有利于环保,采用磷化工艺对AZ31B镁合金进行化学镀镍前处理.采用直观法、扫描电子显微镜和阴极极化曲线法对磷化膜及其化学镀镍层进行了分析.结果表明:AZ31B镁合金表面经磷化处理后得到了良好的化学镀镍层;AZ31B镁合金化学镀镍层的耐蚀性随磷化时间的延长先增加后减小,当磷化时间为75 s时,化学镀镍层的腐蚀电势比直...     

硫酸镍和碱式碳酸镍主盐对镁合金化学镀镍的影响

为了比较镁合金化学镀镍中主盐性质的影响,分别采用硫酸镍(NiSO4·6H2O)和碱式碳酸镍[NiCO3·2Ni(OH)2·2H2O]为主盐对AZ91D镁合金进行化学镀镍.采用扫描电镜(SEM)比较了镀层的表面形貌和组织结构,用能谱(EDS)对2种主盐所得镀层进行成分分析,采用中性盐雾试验比较了不同主盐化学镀镍后镀层的耐腐蚀性,并通过热震和锉刀试验比较两者的结合力,最后在3.5%NaCl溶液中进行动电位极化曲线测试.结果表明,碱式碳酸镍作为镁合金化学镀主盐所得的镀层为高磷镀层,且致密性、耐腐蚀性和结合力均好于硫酸镍作为主盐的镀液.     

AZ31镁合金酸性化学镀Ni-Co-P层的耐腐蚀性能

为了提高镁合金的耐蚀性,以酸性化学镀的方法在AZ31镁合金表面制备了Ni-Co-P镀层。分别用XRD,SEM和EDS对镀层的结构、表面形貌和成分进行了分析,并用点滴试验和电化学方法测试了镀层的耐蚀性。结果表明:酸性化学镀Ni-Co-P层为非晶态胞状结构,镀层中P含量可高达9.41%,远高于碱性镀层;AZ31镁合金镀覆Ni-Co-P合金层后腐蚀电流比基体降低3个数量级,其耐蚀性能显著提高。     

Compressive Deformation of Semi-Solid AZ91D Magnesium Alloy

The compression tests of semi-solid AZ91D Mg alloy have been conducted on a parallel-plate viscometer. The results are as follows. With increasing the compression temperature, the deformation rate or the strain rate of the specimens rises, but the compressive stress continuously decreases; the deformation strain is obviously linear with the compressive stress and independent on compression temperature under a given compression load. In the wake of the compression load being added, the compressive strain increases but the compressive stress decreases clearly; the deformation strain is obviously linear with the compressive stress under different compression load. The mathematical apparent viscosity model about the semi-solid compressed AZ91D Mg alloy has been established, i.e. ηapp=2004.2exp(15.61fs)γ1.317fs-1.3511.     

镁合金化学镀镍层的性能研究

化学镀镍是镁合金保护的重要手段.为探讨化学镀镍对镁合金的保护效果,本文利用电化学极化曲线、X射线衍射和扫描电镜等手段研究了镁合金化学镀镍前处理方法及镀层性能.镁合金上化学镀镍层厚度达到15μm时已没有惯穿镀层的孔隙,200℃以上热处理可显著提高镀层结合力;由于镀层和镁合金间强烈的电偶腐蚀作用,在户外或潮湿环境中,化学镀镍对镁合金而言是一种有较大风险的防护方法.为获得更好的保护效果,多层化学镀或电镀与化学镀相结合是较好的选择.     

AZ91D镁合金表面熔盐置换扩散涂层组织及耐腐蚀性能研究

采用AlCl3-NaCl熔盐自发置换扩散工艺在AZ91D镁合金表面制备镁铝金属间化合物涂层,并利用开路电位、电化学阻抗方法对镁合金及熔盐置换扩散改性处理试样在3.5%(质量分数)NaCl溶液中的腐蚀行为进行比较研究。结果表明:熔盐自发置换扩散铝涂层在温度为400℃,保温8h的工艺条件下呈现出了明显的分层结构特征。根据组织结构不同,可将其分为:颗粒状形貌的外层和具有网状结构的内层;经表面熔盐自发置换扩散处理后的镁合金试样,腐蚀电位比未改性的AZ91D镁合金大幅提高,膜层阻抗约为未改性的AZ91D镁合金的10倍。     

Investigation on a Non-cyanide Plating Process of Ni-P Coating on Magnesium Alloy AZ91D

In this research we presented a non-cyanide plating process of Ni-P alloy coating on Mg alloy AZ91D. By applying a new process flow of electroless nickel plating in which zinc coating is used as transition of Ni-P coating on Mg alloy AZ91D, the process of copper transition coating plated in the cyanides bath can be replaced. A new bath composed of NiSO4 was established by orthogonal test. The results show that zinc transition coating can increase the adhesion and pH 4.0 and 95℃, respectively. The present process flow is composed of ultrasonic cleaning→alkaline cleaning→acid pickling→activation→double immersing zinc→electroplating zinc→electroless nickel plating→passivation treatment.The present non-cyanide process of electroless nickel plating is harmless to our surroundings and Ni-P coating on Mg alloy AZ91D produced by present process possesses good adhesion and corrosion resistance.     

Preparation and Performance of Electroless Nickel on AZ91D Magnesium Alloy

The corrosion of magnesium alloy in different plating solutions was researched. The results demonstrated that corrosive condition of the alloy immersed in nickel chloride solution and nickel sulfate solution is serious and in nickel acetate solution and nickel nitrate solution is less. Magnesium alloy was handled with four acid pickling formulas and two activation formulas and the effects of different pickling formulas and activation formulas were researched through comparative experiment. The experimental results indicated that after handed with pickling formula about 500 mL L^?1 H₃PO₄ (85%), 110 mL L^?1 HNO₃ (68%), room temperature for 30 s and activation formula about 375 mL L^?1 HF (40%), room temperature for 10 min, magnesium alloy could realize electroless nickel plating directly and the performance of the prepared plating was much better. The properties of the nickel-plating coating were researched by electrochemical workstation, scanning electron microscope, and X-ray diffraction. The results demonstrated that this Ni–P coating was very uniform and meticulous; the structure of Ni–P coating was amorphous; and comparing with magnesium alloy, the corrosion potential of this plating increased about 799 V and the corrosion current density declined obviously. The nickel-plating coating effectively improved the anticorrosion performance of magnesium alloy.