Cu-Ni/P双层镀研究

实验研究了化学镀cu-N/P 双镀层和传统的Ni/P镀层在表面形貌、耐蚀性能和硬度方面的差异.结果表明,Cu-Ni/P双镀层比Ni/P镀层具有更好的耐蚀性能和更高的硬度.     

纳米Si_3N_4/Ni复合镀层对金刚石节块性能的影响

用滚镀的方法在金刚石表面镀Ni层和纳米Si_3N_4/Ni复合镀层,用扫描电子显微镜观察金刚石镀前和镀后的表面形貌,用DKY-1型单颗粒抗压强度测定仪测量金刚石单颗粒的抗压强度。用热压烧结的方法得到铁基结合剂金刚石节块,在INSTRON-5569型万能材料试验机上测量节块的抗弯强度,在NMW-1立式万能摩擦磨损试验机上测试节块的耐磨性。结果表明:在金刚石表面镀Ni层和纳米Si_3N_4/Ni复合镀层后,表面镀层均匀,纳米Si_3N_4/Ni复合镀层比纯Ni层更致密,更平滑,晶粒更细小;纳米Si_3N_4/Ni复合镀层金刚石单颗粒有更高的抗压强度;纳米Si_3N_4/Ni复合镀层金刚石铁基结合剂节块有更高的抗弯强度和更优良的耐磨性。     

热处理对钛表面Ni—P合金镀层性能影响的研究

研究了钛表面Ni—P合金镀层的热处理工艺,通过分析镀层的表面形貌及物相组成,探讨了热处理温度等关键因素对Ni—P合金镀层硬度的影响。研究结果表明,在300℃热处理时,电镀时间为1h的镀层中只有Ni5P4相和M,无Ni3P相,电镀时间为2h和3h的镀层中仅有少量的Ni3P相;在400℃热处理时,镀层均由大量Ni3P相和微量Ni组成;400℃热处理后的镀层硬度高于镀态和300℃热处理后的硬度;电镀时间为2h,热处理温度为400℃时,Ni—P镀层硬度最高,维氏硬度达到8938MPa。     

Ni-Fe合金电镀的研究

用Ni—Fe合金电镀工艺取代传统的Ni—W—P化学镀工艺，得到的Ni—Fe合金镀层比Ni—W—P镀层更均匀、更细致，同时具有更高的硬度、耐磨性和耐蚀性能。     

化学镀法制备Ni/TiH2复合粉末的显微组织及其Ni镀层的生长和作用机理

采用化学镀法对TiH2粉末表面镀Ni,制备Ni/TiH2复合粉末。通过X射线衍射(XRD)、扫描电镜(SEM)、能谱分析(EDS)及差热分析(DSC/TG)对Ni/TiH2复合粉末进行表征,探索Ni镀层的生长及作用机理,建立镀层在粉末表面的生长模型。结果表明:施镀温度为85℃时Ni/TiH2复合粉末表面Ni层包覆完整,镀层均匀致密,Ni层厚度约为1.0~2.0μm;施镀温度低于65℃时施镀几乎无法进行,而施镀温度高于95℃时,镀层很不均匀,且容易脱落;镀层的生长机制遵循奥斯特瓦尔德(Ostwald ripening)机制;与包覆前TiH2粉末相比,Ni/TiH2复合粉末的释氢反应开始温度由450℃上升至540℃。包覆层可降低TiH2粉末和熔融铝的温度梯度,从而推迟开始释氢的时间。     

化学镀法制备镍包石墨复合粉末

采用化学镀法在石墨粉末表面镀镍制备Ni/石墨复合粉末,采用激光衍射粒度分析、扫描电镜等对Ni/石墨复合粉末的粒度和表面形貌进行表征,研究镀液中主盐硫酸镍、还原剂联氨及活化剂氯化钯的浓度对该复合粉末表面形貌的影响,并对Ni镀层在石墨表面的生长机理进行探讨.结果表明:硫酸镍质量浓度为20 g/L、联氨体积分数为2％时,化学...     

双辉法等离子渗镀TiN层及耐磨和耐蚀性能的研究

一种利用双层辉光等离子溅射直接复合渗镀合成TiN渗镀层的新工艺方法。该TiN渗镀层表面形貌为‘胞状’组织,颗粒致密均匀,表面为金黄色。TiN渗镀层由TiN颗粒均匀分布的扩散层及表面TiN沉积层组成,渗镀层厚度可达16μm,与基体形成固态冶金层,结合强度高,表面平均显微硬度为3120 HV。对该TiN渗镀层试样,未处理的Q235钢试样,T10淬火+回火试样和3Cr13渗氮试样在相同的条件下进行了耐磨性试验;将该渗镀层试样与未处理的Q235钢和1Crl8Ni9Ti不锈钢试样在1 mo.lL-1H2SO4溶液和3.5%的NaCl溶液中,分别进行了电化学腐蚀对比试验。结果表明:在相同的条件下,TiN渗镀层相对磨损速度最小,耐磨性较未处理的Q235钢试样提高7.81倍,较T10淬火+回火试样提高5.625倍,较3Cr13渗氮试样提高7倍;在浓度为1 mol.L-1的H2SO4溶液中,TiN渗镀层耐腐蚀性能比未处理的Q235钢提高了11.5倍,比1Crl8Ni9Ti不锈钢提高了2.65倍。在浓度为3.5%的NaCl溶液中,TiN渗镀层的耐腐蚀性能比未处理的Q235钢提高11.3倍,但比1Crl8Ni9Ti不锈钢耐蚀性能稍差。     

化学镀镍法制备中空镍纤维

采用化学镀的方法制备中空镍纤维,通过对不同纤维进行筛选和优化,选取晴纶纤维作为化学镀镍的基体,纤维直径约10 μm,长度3 mm左右.采用NaH2PO2为还原剂的碱性低温镀液体系在晴纶纤维表面镀镍,通过SEM,EDS和XRD分析了镀层表面形貌、结构和化学成分.研究发现,未经烧结的Ni/晴纶复合纤维镀层致密均匀,主要成分为低磷含量的Ni-P合金.将复合纤维先在空气中进行氧化烧结去除晴纶基体,发现烧结温度对去除有机基体得到中空镍纤维有较大影响.当烧结温度低于300℃时,有机基体去除不完全;当烧结温度为400℃时,基本没有有机基体残留,管壁致密;当温度为500℃时,得到的中空氧化镍纤维管壁有大量微孔,质脆易碎.将去除基体后的氧化物在氢气气氛下进行高温还原处理,得到中空镍纤维,组成为Ni和Ni3P,镍元素占93.83%(质量分数).     

烧结NdFeB磁体化学镀Ni-P/Ni-Co-P镀层组织结构特征

采用化学镀方法在烧结钕铁硼表面制备了Ni-P/Ni-Co-P合金镀层,研究了Ni-P预镀层与多孔基材界面结合特征、不同金属离子浓度比[Co2+]/[Ni2++Co2+]对镀层成分、组织结构及表面形貌的影响。结果表明:Ni-P预镀层与钕铁硼基材呈犬牙交错,增加了界面的有效结合面积,提高了结合强度,说明预镀层溶液具备较强的深镀能力;Ni-P/Ni-Co-P镀层间结合紧密,两者具有优异的相容性和相似的结构特征。Ni-Co-P镀层表面由不同尺寸胞状物组成,组织致密,孔隙率几乎为零;随金属离子浓度比值的增加,镀层表面颜色由暗银白色变为亮银白色,镀层中Ni和P含量降低,Co含量增加,表明镀层成分与镀液中主盐金属离子的浓度密切相关。XRD分析结果表明,随金属离子浓度比的增加,镀层呈现由非晶结构向微晶结构转变的趋势。在金属离子浓度比为0.3~0.5范围内,镀层表面胞块尺寸随金属离子浓度比的增加而减小;当金属离子浓度比值增至0.6时,镀层表面胞块尺寸变大,且呈微晶形态,说明在0.5~0.6之间存在一临界值,小于此值,镀层组织结构为细小的非晶态胞块形貌,大于此值,镀层则由非晶态结构开始发生向微晶组织结构转变。     

金刚石表面镀层在电火花烧结过程中的行为及对制品性能的影响

用抗弯强度及测量颗粒出露高度的方法研究了表面镀覆Ti及Ti Ni的金刚石在电火花脉冲放电烧结条件下镀层的行为，研究了镀层对制品抗弯强度及颗粒出露高度的影响，在体视显微镜下观察了金刚石表面镀层与镀层之间、镀层与金属颗粒之间的放电及熔焊现象。研究表明，表面具有金属性质的镀覆Ti及Ti Ni镀层金刚石能够参与粉末冶金过程中的脉冲放电烧结，有熔焊现象，增加了金刚石颗粒与基体金属的把持能力，从而大幅度提高了制品的抗弯强度及颗粒出露高度。     

Effect of frequency and duty cycle on corrosion and wear resistance of functionally graded Zn–Ni nanocomposite coating

In this study, functionally graded Zn–Ni nanocomposite coatings with a nanoparticle mix of 80?wt-% alumina, 5?wt-% yttria and 15?wt-% graphene were electrodeposited on a mild steel substrate by the pulsed current method. The effects of pulse parameters such as frequency and duty cycle on chemical composition, microstructure, corrosion resistance and tribological properties of coated specimens were evaluated. The coatings were formed through changing the duty cycle from 10% to 90% in five steps during the coating process and different frequencies of 500, 1000, 3000 and 5000?Hz. A continuous decrease in the duty cycle led to an increase of the nanoparticles embedded in the coating structure from the interface to the surface, so that most increments corresponded to the sample with a 500?Hz frequency and was 1.41?wt-%. By increasing the frequency, Ni and nanoparticle content in the coating surfaces increased up to 3.6?wt-% and 1.82?vol.-%, respectively. In particular, by increasing the frequency and nanoparticle content in the coatings, corrosion and wear resistance of coatings improved.     

Study on characteristics of Ni-W-B composites containing CeO2 nano-particles prepared by pulse electrodeposition

Ni-W-B composites containing CeO2 nano-particles on the surface of 45 steel were prepared by pulse electrodeposition,and the in-fluence of pulse frequency,pulse duty circle and heat treatment temperature on the structures and properties were investigated.The results in-dicated that the pulse co-deposition of Ni,W,B and CeO2 nano-particles led to Ni-W-B/CeO2 composites possessing higher microhardness and better wear resistance when heat-treated at 400 oC for 1 h.The microhardness of 636 HV and the deposition rate of 0.0281 mm/h of the as-deposited alloy were the highest at pulse frequency of 1000 Hz,pulse duty circle of 10% and pulse average current density of 10 A/dm2.The composites were mainly in the amorphous state and were partially crystallized as-deposited,and the crystallization trend was strength-ened when heat-treated at 400 oC.Decreasing pulse duty cycle from 75% to 10% was favorable to the refinement in grain structures and im-provement of microstructures.The crystal sizes of the composites were smaller by means of pulse electrodeposition.     

A Study on the Effect of Pulse Electrodeposition Parameters on the Morphology of Pure Tin Coatings

Pure Sn coatings are prepared by pulse current (PC) electrodeposition using aqueous acidic sulfate plating bath. The effects of various electroplating parameters such as current density, additive concentration, duty cycle, frequency, pH, bath temperature, and stirring rate (bath rotation) on the evolution of surface morphology of the coatings have been studied. The as-deposited coatings are characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and surface profilometry. It is found that the current density, additive concentration, duty cycle, frequency, and pH have a major influence while temperature and stirring rate of the bath have a minor effect on the grain-size distribution. The mechanism involved in the morphology evolution and grain-size distribution due to the varying electroplating parameters has also been discussed.     

Functionally graded nickel–tungsten coating: electrodeposition,corrosion and wear behaviour

Nickel–tungsten functionally graded (FG) coatings were developed by pulse electrodeposition. To make a FG structure, pulse parameters were selected in eight layers with the tungsten content increasing along the thickness. The gradual increase in tungsten content to the surface will increase wear resistance and reduce the risk of cracking at the substrate. To investigate the microstructure and cross-section of Ni–W coating scanning electron microscope and to measure the chemical composition of the coating the energy dispersive spectroscopy analysis was used. Electrochemical and pin-on-disk wear tests were performed to investigate corrosion resistance and wear behaviour of the coating, respectively. Results showed that with reduction of duty cycle or increasing of frequency along this eight-layer structure, the tungsten content increased upward the surface. Results showed the superior wear resistance of the coating as compared to that of pure nickel. Moreover, the coefficient of friction decreased from 0.74 to 0.49 by an increase in the sliding distance.     

Improving the Corrosion Resistance of the Nickel–Tungsten Alloy by Optimization of the Electroplating Conditions

Nickel–tungsten (Ni–W) alloy coating was electrodeposited on the copper substrate by direct current voltammetry. The optimization of a free-ammonium bath for electrodeposition of Ni–W alloy coating was investigated. Experiments were focused on elucidating the effect of W concentration and operating conditions on the corrosion performance of the obtained Ni–W alloy coating. The corrosion behavior of the coatings was investigated by potentiodynamic polarization (Tafel) test. Experimental data such as corrosion current density, corrosion rate and polarization resistance indicated that the operating conditions used during the electroplating had significant effects on the corrosion parameters of the Ni–W alloy coating. The results showed that the highest corrosion resistance was obtained for the coating with 56.7 wt% tungsten (Ni/W ratio of 1:2.5) which was prepared at the current density of 3.8 A dm^?2. The increase in the corrosion resistance at the optimum current density was attributed to the lower interferences of the hydrogen evolution reaction. Energy-dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM) and X-ray powder diffraction (XRD) techniques were used to characterize the electrodeposited Ni–W alloy with the best anti-corrosion parameters.

     

Optimization of bright zinc-nickel alloy bath for better corrosion resistance

Optimization of an acid chloride bath for electrodeposition of smooth Zn-Ni alloy on to mild steel was studied using thiamine hydrochloride (THC) as brightener. The influence of deposition current density, temperature, composition, and corrosion properties of Zn-Ni alloy coatings was investigated. The effect of bath composition and operating parameters on deposits characters like composition, micro-hardness, thickness and adhesions were tested. Under no conditions of current density employed in the present study, the anomalous type of co-deposition has changed to normal type. Electrolytically deposited Zn-Ni alloys were characterized by electrochemical AC and DC techniques. The experimental results revealed that coatings having ∼ 3.16 wt. % Ni at 3.0 A/dm² was the most corrosion resistant. The better corrosion resistance at optimal current density was attributed to the formation of n-type semiconductor film at the interface using Mott-Schottky (M-S) analysis. The effect of THC on plating process was investigated through cyclic voltammetry techniques. X-ray diffraction (XRD) studies of the coatings showed the presence of γ-Phase with composition of Ni₅Zn₂₁, responsible for it extended orrosion resistance. The change in the surface morphology of the coatings, with current density was analyzed using scanning electron microscopy (SEM).     

Alkaline Electrodeposition of Ni–ZnO Nanocomposite Coatings: Effects of Pulse Electroplating Parameters

The effects of applied current density (1–10 A/dm²), pulse frequency (1–100 Hz) and duty cycle (10–75 %) on the morphology and microhardness of Ni and Ni–ZnO coatings, incorporation rate of ZnO nanoparticles, current efficiency and deposition rate were investigated. Ni–ZnO composites exhibited a nodular morphology. At low current densities, smooth and compact Ni–ZnO coatings were obtained. As the current density increased more gaps and defects appeared on the coatings surface. Maximum incorporation rate of 4.04 vol% was achieved at the current density of 10 A/dm². Presence of ZnO nanoparticles in the electrolyte improved the current efficiency of the process and deposition rate of the matrix. The microhardness values of the composites were considerably higher than those of the nickel coatings.     

脉冲参数对电解金属锰的影响

改变占空比、频率、电流密度,探讨脉冲电流对电解金属锰电流效率的影响规律,并与直流电解金属锰进行比较。占空比为0.5、频率为100Hz、电流密度为400A/m2时脉冲电解金属锰的电流效率最高,达到82.1%。在相同电流密度条件下,脉冲电解金属锰的电耗比直流电解金属锰低38.0%。通过XRD、SEM对电解金属锰层进行表征,结果表明：脉冲电解金属锰的沉积层更加平整光滑,颗粒的形貌更加均匀、细致及紧密,成分更纯净。     

织构对纳米晶纯镍镀层耐蚀性能的影响

采用脉冲电镀法在黄铜表面制备出具有(111)、(200)和(220)晶面择优生长织构的纳米晶纯镍镀层.采用扫描电镜对镀层的显微形貌进行观察,采用X射线衍射对不同晶面织构的择优性进行表征,并对镀层在3.5%NaCl溶液中的动电位极化曲线和交流阻抗谱进行了测试,研究不同织构镀层的耐蚀性能.不同织构镀层的耐蚀性能存在显著差异:具有(220)强织构的镀层耐蚀性最差,其自腐蚀电流密度最大,为1.23μA·cm-2,镀层的电荷转移电阻为2.09kΩ·cm2;具有(200)强织构的镀层耐蚀性能最佳,镀层的电荷转移电阻为27.32kΩ·cm2,自腐蚀电流密度为0.15μA·cm-2;具有(111)织构镀层的耐蚀性居中.认为织构引起的表面胞状物的差别是造成纯镍镀层耐蚀性能不同的原因.      

铜锡合金电镀技术研究

研究电流密度对铜锡合金镀层致密性、硬度及耐蚀性能的影响。试验结果表明，在1．0A／dm^2电流密度下得到的铜锡合金镀层具有良好的致密性和耐蚀性。