电沉积及激光辅助电沉积镍基镀层表面形貌研究

采用电沉积技术和激光辅助电沉积技术制取了Ｎｉ－Ｐ,Ｎｉ－Ｗ－Ｃｏ合金镀层和Ｎｉ－Ｐ、Ｎｉ－ Ｗ－Ｃｏ与硬质颗粒ＳｉＣ、Ｂ４Ｃ共沉积形成的复合镀层．用光学显微镜和扫描电镜观察了不同 的施镀条件下镀层的表面形貌,分析了其变化的影响因素．分析结果表明：沉积速度和颗 粒的添加量是影响镀层表面形貌的两个重要因素．     

电沉积Ni-Co-Cr合金镀层及其耐蚀性研究

采用电化学恒电流技术在铜基体上沉积制备了Ni-Co-Cr三元合金镀层,研究了电流密度、温度及pH值对合金镀层成分的影响.利用SEM和EDS研究了Ni-Co-Cr合金镀层的形貌与成分,通过交流阻抗技术研究了镀层的耐蚀性.采用弯曲实验法测定了镀层的结合力.结果表明,在阴极电流密度为100 mA/cm2,镀液温度为25℃,pH为2.5条件下沉积的合金镀层致密均匀,化学组成中Cr含量达到最高(达到10％,该成分为10.22％ Cr,21.61％ Ni,59.86％ Co,质量分数,氧和铜含量未计入),具有优化耐蚀性.     

脉冲电沉积Ni-W-P系多元复合镀层性能研究

主要研究了Ni-W-P-SiC，RE-Ni-W-P-SiC，RE-Ni-W-P-SiC-MoS2，RE-Ni-W-P-SiC-PTFE直流及脉冲复合镀层的硬度、磨损率、相结构及形貌．结果表明：脉冲镀层的硬度均高于直流镀层，但RE-Ni-W-P-SiC-PTFE复合镀层的硬度较低．四种复合镀层的硬度随热处理温度的升高而增加，在400℃时达到最大值，此后，热处理温度继续升高，复合镀层硬度反而下降；频率为50Hz，占空比为0．6和0．8时，RE-Ni-W-P-SiC镀层的硬度最高．占空比为0．8时的镀层，其硬度均高于占空比为0．6的镀层；Ni-W-P-SiC，RE-Ni-W-P-SiC，RE-Ni-W-P-SiC-PTFE脉冲镀层的磨损率明显低于直流镀层，且RE-Ni-W-P-SiC-MoS2和RE-Ni-W-P-SiC-PTFE脉冲镀层的磨损率最小；Ni-W-P-SiC，RE-Ni-W-P-SiC脉冲镀层镀态下为非晶态结构，RE-Ni-W-P-SiC-MoS2脉冲镀层镀态下为混晶结构，而RE-Ni-W-P-SiC-PTFE脉冲复合镀镀态下为晶态结构；脉冲镀层的晶粒粒度要小于直流镀层，加入RE有细化晶粒的作用，各种微粒均匀分布在镀层中，镀层表面及断面没有裂纹．     

电沉积Ni-Co-Cr合金镀层的电化学性能

采用电化学恒电流技术在铜基体上沉积制备了Ni-Co-Cr三元合金镀层,研究了柠檬酸钠、硼酸及十二烷基硫酸钠对合金镀层的耐蚀性能影响.结果表明：在柠檬酸钠的浓度为200 g/L,糖精的浓度为1.4 g/L,硼酸的浓度为40 g/L,十二烷基硫酸钠的浓度为0.18 g/L,在此条件下沉积的合金镀层耐蚀性能最佳.     

电沉积Ni—WC 合镀层特性的研究

研究了Ni-WC复合材料镀层的电沉积工艺及热处理和WC微粒对Ni复合镀层的影响 ,同时对其组织结构、硬度、结合强度、孔隙率等也作了测定和讨论 .结果表明 :本文的试验工艺 ,可成功地电沉积出结合力好和孔隙率低的Ni-WC复合镀层 ;随着WC含量的增加 ,镀层的硬度也得到提高 .镀层经适当的热处理后 ,硬度可得到进一步提高     

ChCl-Urea低共熔溶剂中Ni-P合金的电沉积行为研究

以氯化胆碱-尿素(ChCl-Urea)低共熔溶剂为基础液,电沉积制备Ni-P合金镀层。采用循环伏安和计时电流技术对Ni-P合金镀层的电沉积机理进行研究,使用扫描电子显微镜(SEM/EDS)和X射线衍射(XRD)对镀层的微观形貌、元素组成和物相组成进行表征,利用动电位极化曲线对镀层的耐腐蚀性能进行分析。结果表明,Ni-P合金镀层在ChCl-Urea-NiCl₂-NaH₂PO₂低共熔溶剂中的电沉积过程是受扩散步骤控制的不可逆过程,且成核机理为三维连续成核,该体系下可制得光亮、平滑、致密的镀层。     

电泳-电沉积法制备Ni-Fe2O3复合镀层 及其氧化性能研究

先采用电泳沉积工艺在Ni基体上均匀沉积Fe2O3膜,然后采用电镀技术在Fe2O3膜中沉积金属Ni,得到含Fe2O3质量分数较高的Ni-Fe2O3复合镀层。分析了沉积电压对电泳沉积Fe2O3膜厚度的影响,研究了镀层的高温氧化性能,并对其氧化机理进行了探讨。使用傅里叶红外光谱、扫描电镜、能谱仪、X射线衍射仪对镀层的截面形貌、成分等进行了研究。结果表明:通过改变阴阳两极之间的电场强度或调整两极之间的距离,电泳沉积Fe2O3的厚度会发生很大的变化;经过一定温度热处理后,电泳沉积层中的有机物去除干净;使用电泳-电沉积法制备的Ni-Fe2O3镀层与基体之间的结合界面紧密、完整;复合沉积层在1 000℃高温条件下氧化后可以得到镍铁尖晶石结构的物质。     

铝合金上电沉积Ni-P-CNTs复合镀层及其摩擦性能研究

采用复合电沉积法在铝合金表面上制备了镍 磷 碳纳米管（Ni-P-CNTs）复合镀层,并用X射线衍射（XRD）和扫描电镜（SEM）对其进行了表征,分析了电流密度和镀液中碳纳米管的质量浓度对复合镀层形貌及其摩擦磨损性能的影响.当电流密度为3.0 A/dm2时可以得到表面光亮、平整的复合镀层,复合镀层中碳纳米管体积分数随着镀液中碳纳米管质量浓度的增加而增加.Ni-P-CNTs复合镀层比Ni-P镀层具有更高的硬度、耐磨性能和更低的摩擦系数.随着复合镀层中碳纳米管体积分数的增加,复合镀层的磨损量和摩擦系数逐渐降低.复合镀层摩擦性能的改善是由于碳纳米管具有优异的力学性能和良好的自润滑性能.     

金属锌电沉积的分形研究

以环形金属锌板作为阳极,石墨棒作为阴极,对电沉积过程中金属锌的二维枝晶生长进行了研究,并对不同电沉积条件下所得到的沉积产物的分形维数和宏观形貌进行了观察、分析.研究表明,随外加电压的升高,金属锌二维沉积产物的形貌由开放的枝状晶向致密的粗大枝晶转变,分形维数也呈增大趋势;随着电解质溶液中硫酸锌浓度的增加,阴极沉积产物先后出现了类似于DLA模型模拟结果的枝状形貌、具有分叉结构的致密纤维状枝晶簇和较为粗壮的开放型规则分叉状枝晶等不同形貌,分形维数亦随之发生相应的改变.     

Fe-Ni-Cr系软磁合金的正交实验研究

在正交实验基础上,采用方差分析方法,研究了两种成分软磁合金在不同热轧变形量、退火温度、保温时间及冷却方式等工艺条件下,磁性能的变化规律.结果表明,化学成分是影响软磁合金磁化率的最主要因素,其次是热变形量和退火温度.得出提高该材料磁化率的最优工艺方案为:配料应接近第一种试样钢成分,热变形量应20%以下,退火温度650 ℃,保温时间30 min.     

Effects of electroplated coatings on corrosion behavior of Ti-1023/30CrMnSiA galvanic couple

Galvanic corrosion behavior of Ti-1023 titanium alloy coupled 30CrMnSiA steel was investigated in 3.5% NaCl solution. Particular attention was given to the effect of three different electroplated coatings on corrosion behavior of the galvanic couple. Galvanic corrosion test was conducted on Ti-1023 titanium alloy which coupled Ni-electroplated 30CrMnSiA, Zn-electroplated 30CrMnSiA, Cd-electroplated 30CrMnSiA and bare 30CrMnSiA, respectively. Corrosion properties including open circuit potential （Eoc）, galvanic corrosion potential （Eg）, and galvanic corrosion current （lg） were monitored. Corrosion morphology was observed by optical microscope （OM） and corrosion mechanism was analyzed and discussed. The results show that the three electroplated coatings improve the corrosion resistance of the anode in different magnitudes. Ni-electroplated 30CrMnSiA and Cd-electroplated 30CrMnSiA coatings are found to be least susceptible to galvanic corrosion when coupled Ti-1023 titanium alloy. Zn-electroplated 30CrMnSiA is moderately susceptible to galvanic corrosion. But the bare 30CrMnSiA is highly susceptible to galvanic corrosion in corrosive environment.     

Electrochemical corrosion behavior of carbon steel with bulk coating holidays

With epoxy coal tar as the coating material, the electrochemical corrosion behavior of Q235 with different kinds of bulk coating holidays has been investigated with EIS （Electrochemical Impedance Spectroscopy） in a 3.5vo1% NaCI aqueous solution. The area ratio of bulk coating holiday to total coating area of steel is 4.91%. The experimental results showed that at free corrosion potential, the corrosion of carbon steel with disbonded coating holiday is heavier than that with broken holiday and disbonded ＆ broken holiday with time; Moreover, the effectiveness of Cathodic Protection （CP） of carbon steel with broken holiday is better than that with disbonded holiday and disbonded ＆ broken holiday on CP potential -850 mV （vs CSE）. Further analysis indicated that the two main reasons for corrosion are electrolyte solution slowly penetrating the coating, and crevice corrosion at steel/coating interface near holidays. The ratio of impedance amplitude （Z） of different frequency to minimum frequency is defined as K value. The change rate of K with frequency is related to the type of coating holiday.     

镁合金电镀镍涂层的耐蚀性能

以化学镀镍作为保护层,对AZ91D镁合金进行直流电镀镍涂层以提高其耐腐蚀性能,并对镁合金表面两个不同厚度的镀镍涂层进行了比较.采用SEM对涂层的表面形态进行了研究.在X射线下纹理明显.镍涂层硬度约560VHN,远远高于AZ91D镁合金基底的硬度(约100VHN).电化学测量结果表明,在已经研究的镁合金涂层中,镍镀层有最低的腐蚀电流密度和最高的腐蚀电位.加速腐蚀实验中AZ91D镁合金镀镍具有很高的耐腐蚀性能.     

HVOF喷涂Co基WC涂层的耐锌腐蚀行为

为了提高热镀锌用辊件的耐腐蚀性,试验采用超音速火焰喷涂方法制备WC-12Co涂层,研究了涂层在450 ℃锌液中的耐腐蚀性能以及失效机制.将316L/WC-12Co涂层进行液锌腐蚀,以扫描电镜能谱分析、x-射线衍射方式分析对比了未经过腐蚀试件、腐蚀5天试件、腐蚀10天试件的组织变化和相组成,结果显示涂层基体Co受液锌腐蚀生成Co与Zn化合物,引发横向裂纹,导致涂层剥落.涂层全部剥落后保护失效,使母材被液锌直接严重腐蚀,最终生成锌渣FeZn₁₃.     

热喷涂涂层与电镀层的结合与界面

为提高热喷涂涂层与电铸层间的结合强度,分别选用QAl9-2、Ni95Al5和0Cr25Al5等3种自结合材料做过渡层,沉积在电弧喷涂3Cr13涂层与电铸Ni层之间.结果表明,Ni95Al5过渡层的效果最好,可提高涂层体系结合强度至少一倍,QAl9-2与0Cr25Al5过渡层的效果次之.借助于扫描电子显微镜,分析了热喷涂涂层与电铸层界面的微观组织,研究了过渡层的强化机制.在该涂层体系中,自结合涂层与电铸镍层发生冶金结合,自结合涂层的自由表面为后续沉积的3Cr13涂层提供了极好的机械结合界面,保证了涂层体系的可靠结合.     

In vitro corrosion behavior and cytotoxicity property of magnesium matrix composite with chitosan coating

Mg-6%Zn-10%β-Ca3(PO4)2 composite was prepared through powder metallurgy methods with different chitosan coatings on its surface. The properties of the chitosan coatings on the surface of Mg-6%Zn-10%β-Ca3(PO4)2 composite, such as the adhesion ability, the corrosion behavior and the cytotoxicity properties, were investigated, and the microstructure of the chitosan coating was observed by scanning electron microscope(SEM). The results show that chitosan coating improves the corrosion resistance of the magnesium composite specimens significantly. Mg-6%Zn-10%β-Ca3(PO4)2 composite specimens exhibit good corrosion resistance and low p H values in simulated body fluid(SBF) at 37 °C in the immersion test with 7-layer chitosan coating whose relative molecular mass is 30×104 Da. The cytotoxicity tests indicate that Mg-6%Zn-10%β-Ca3(PO4)2 with chitosan coating is nontoxic with a cytotoxicity grade of zero against L-929 cells, which is better than that of uncoated composites.     

徽量稀土对X70管线钢腐蚀规律研究

采用土壤模拟溶液浸泡方法,通过测试X70管线钢的自腐蚀电位、交流阻抗,并配合扫描电镜,研究了徽量稀土金属铈对X70管线钢腐蚀电化学行为的影响．研究结果表明,随着浸泡时间的延长,试样的腐蚀率先升高后降低又升高．徽量稀土的加入提高了X70管线钢的自腐蚀电位,同时抵制了X70管线钢的均匀腐蚀．     

Sand-wear resistance of brush electroplated nanocomposite coating in oil and its application to remanufacturing

Sand-wear resistance of nano scale alumina particle reinforced nickel matrix composite coating (n-Al₂O₃/Ni) prepared by brush electroplating technique was investigated via wear tests in sand-contaminated oil lubricant, comparing with that of AISI1045 steel and brush electroplated Ni coating. Effects of testing load, sand content and sand size on worn volume of the three materials, and also coating surface roughness on worn volume of the brush electroplated coatings were accessed. Results show that the worn volume of all the three materials increases with increasing of testing load, sand content and sand size. In the same conditions, n-Al₂O₃/Ni composite coating has the smallest worn volume while AISI1045 steel has the largest because of the n-Al₂O₃ particle effects. As to n-Al₂O₃/Ni and Ni coatings, the surface-polished coatings have obviously lower worn volume than the as-plated coatings. The brush electroplated n-Al₂O₃/Ni composite coating was employed to remanufacture the sand-worn bearing seats of a heavy vehicle and good results were gained. Foundation item: Project (50235030) supported by the National Natural Science Foundation of China; Project (51489020104ZD0401) supported by the National Key Laboratory for Remanufacturing; Project(51418060105JB3058) supported by National Defence Foundation