一种碱性电镀锌镍合金镀层的抗腐蚀性能研究

在一种锌镍合金碱性电镀体系中,以四乙烯五胺(TEPA)和三乙烯四胺(TETA)混合物作为镍离子络合剂的碱性电镀锌镍合金体系,在低碳钢基材上电沉积制备锌镍合金镀层.利用电化学工作站测试了镀层在3.5％NaCl溶液中的极化曲线和电化学阻抗谱,考察不同电沉积条件参数(电流密度、镍含量、搅拌等)对锌镍合金镀层的腐蚀电化学行为的影响.结果表明,在3.5％NaCl溶液中的模拟海水溶液中,通过极化曲线测得腐蚀电位和腐蚀电流可知镀液含镍含量一定范围内(Ni2+/Ni2++Zn+=15 mol％～20 mol％,得到的镀层对基体有很好的防护作用;随着电流密度的增大镀层的腐蚀电位变负;腐蚀介质的酸碱性越强对镀层的腐蚀越大.     

退火对电沉积纳米晶镍在不同腐蚀液中耐蚀性影响的研究

采用直流电沉积法制备纳米晶Ni镀层,通过电化学法研究了不同热处理温度下电沉积纳米晶镍的耐蚀性。结果表明：电沉积纳米晶镍在200 ℃以下退火,晶粒尺寸变化不明显,300 ℃退火后,晶粒显著增大,但尺寸仍为纳米级;电沉积纳米晶镍经过200和300 ℃的退火处理,有利于改善抗高浓度NaOH和NaCl腐蚀液腐蚀的能力;纳米晶镍在NaOH和NaCl腐蚀液中的耐蚀性能不同,Cl^-对纳米晶镍的腐蚀性远高于OH^-腐蚀。     

316L不锈钢表面超疏水微纳镍镀层定向电沉积工艺优化研究

利用定向电沉积技术在316L不锈钢表面设计制备了一种超疏水微纳镍镀层,通过对电沉积参数的优化,获得最佳电沉积工艺参数:初次电沉积电流密度5 A·dm~(-2),电沉积时间为480 s,结晶调节剂浓度为1.5 mol/L;二次电沉积条件为10 A·dm~(-2),60s。借助SEM、XRD、电化学测试技术、接触角测试对涂层进行表征,结果表明制备的316L不锈钢表面镍镀层阵列微纳结构具有典型的花瓣状分级结构和较好的超疏水性能,镍镀层阵列微纳结构由具有(110)择优取向晶面的针锥阵列结构组成,随着二次电沉积电流密度的增大,镍镀层阵列微纳结构的生长经历从针锥向花瓣结构转变。     

镍/铜/锌多层镀层的制备及其耐蚀性

采用电沉积法在低碳钢基体上制备了镍/铜/锌多层镀层。采用扫描电镜观察镍/铜/锌多层镀层的微观结构;通过盐水(NaCl质量分数为5%)浸泡试验对制得的镍/铜/锌多层镀层进行耐蚀性评价;利用电化学阻抗谱(EIS)技术测试镍/铜/锌多层镀层在5%NaCl(质量分数)溶液中的电化学性能。结果表明:底层镍镀层颗粒以四角锥型交错堆积,中间层铜镀层颗粒以圆胞型结构沉积,表层锌镀层的表面平整致密,无明显孔隙;镍/铜/锌多层镀层具有较好的耐蚀性,电化学阻抗达到了5 623Ω·cm2,耐盐水浸泡时间可达2 880h时,是相同厚度单一镀层耐盐水浸泡时间的5~8倍。     

含稀土镀液电沉积镍镀层耐蚀性的研究

借用扫描电镜、电化学分析和腐蚀失重实验方法研究了镀液中添加RE经直流和单向脉冲电沉积方法制备的镍镀层的耐蚀性。结果表明：单向脉冲法制备的镍镀层抗腐蚀能力优于直流法制备的镍镀层抗腐蚀能力，其原因主要归于单向脉冲镀层结晶比较细小致密，直流镀层结晶较粗大且致密性差。     

强磁场中电沉积Ni-P合金的研究

在电沉积镍磷合金薄膜的过程中施加与电流方向垂直的强磁场,研究了不同磁感应强度对电沉积Ni-P合金薄膜的微观形貌、组织结构和耐腐蚀性能的影响.结果表明:在电沉积过程中施加强磁场可以提高镀层中的磷含量.从SEM照片中观察到随着磁感应强度的增加,非晶团簇尺寸逐渐变小.通过XRD图谱分析可知Ni-P合金镀层是由非晶态结构和晶态结构的混晶组成,随着磁感应强度的增大,镀层中的镍<111>择优取向增大,电化学分析结果表明镀层的自腐蚀电位也逐渐提高,表明耐腐蚀性能逐渐提高.     

摩擦辅助喷射电沉积纳米晶镍的电化学腐蚀行为

采用摩擦辅助喷射电沉积工艺和传统喷射电沉积工艺制备纳米晶镍,用TEM对比分析了二者的组织结构,用电化学极化法研究了2种纳米晶镍层在3.5%NaCl(质量分数)溶液及1 mol/L H2SO4溶液中的腐蚀行为。结果表明,摩擦辅助喷射电沉积结晶过程更加均匀,制备的纳米晶镍层组织致密,晶粒细小,平均晶粒达到9.77 nm;在2种腐蚀溶液中,摩擦辅助喷射电沉积制备的纳米晶镍的电化学腐蚀性能均优于传统喷射电沉积;在NaCl溶液中,摩擦辅助喷射电沉积所制纳米晶镍在腐蚀过程中有钝化膜产生。并指出晶粒大小与微观缺陷是影响纳米晶镍耐腐蚀性能的2个重要因素     

脉冲电沉积纳米晶Ni-Co合金镀层腐蚀特性研究

采用X射线衍射(XRD)、扫描电镜(SEM)、能谱分析(EDS)等方法研究了脉冲电沉积法制各纳米晶Ni和纳米晶Ni-Co合金镀层的组织结构、表面形貌和成分.用浸泡法和电化学极化法研究了纳米晶Ni和不同Co含量的纳米晶Ni-C0合金镀层在3.5%NaCl(质量分数,下同)和5%HCl溶液中的腐蚀行为.结果表明:通过脉冲电沉积法制各的Ni和Ni-Co合金镀层具有典型的纳米晶结构; 随着含Co量的增加,镀层的晶粒尺寸减小,硬度增加;所制备的纳米晶Ni-Co合金镀层组织结构均匀致密,其在3.5%NaCl溶液和5%HCl溶液中的耐蚀性均优于纳米晶Ni镀层;纳米晶Ni-Co合金镀层在3.5%NaCl溶液的浸泡腐蚀中腐蚀极少,表现出优异的耐腐蚀性能,而在5%HCl溶液中的腐蚀形态则为均匀腐蚀.     

负压-温度梯度电沉积镍镀层的耐腐蚀性

在负压-温度梯度环境下制备镍镀层,并研究分析不同电沉积工艺条件和参数(如沉积空间气压、阴极面温度、阴极电流密度、添加剂等)对镍镀层在10%HCl溶液和10%H2SO4溶液中的耐腐蚀性的影响。结果表明:无添加剂镀液中制备而成的镍镀层在两种酸性溶液中的腐蚀率均随沉积空间气压(20～5kPa)的降低及阴极面温度(40～65℃)的升高而减小,随阴极电流密度(3～81A/dm2)的增加而增大;相同操作条件下,镀液中加入适量十二烷基硫酸钠添加剂后所得镍镀层的腐蚀率更低。与常态环境(常压、大气环境)下获得的镍镀层相比,负压-温度梯度环境下电沉积的镍镀层的耐腐蚀性增强。     

电沉积电位对锌镍合金镀层耐蚀性的影响

采用电化学沉积方法在DH36船板钢表面制备了锌镍合金镀层。采用扫描电镜(SEM),能谱仪(EDS)和X射线衍射仪(XRD)等研究了电化学沉积电位对锌镍合金镀层形貌、化学成分和晶体结构的影响。结果表明:随着沉积电位的升高,锌镍合金镀层由无法覆盖整个基底表面到均匀致密覆盖,再到较大微纳米颗粒层覆盖,证明沉积速率越来越大。由EDS和XRD分析可知,在较低电位下沉积,锌镍电沉积过程属于正常共沉积,而在较高电位沉积时,锌镍电沉积过程属于异常共沉积。电化学极化曲线测试表明,在电沉积电位为-1.2 V时所获得的锌镍合金镀层的耐腐蚀性最好。     

Microstructure and properties of nanocrystalline nickel coatings prepared by pulse jet electrodeposition

The fabrication of nanocrystalline nickel coatings was conducted by pulse jet electrodeposition on the substrate of 45# carbon steel. The effects of average current density on the surface morphology, microstructure, average grain size and microhardness of nickel coatings were investigated by scanning electron microscopy (SEM), X-ray diffractometry (XRD) and microhardness measurement. In addition, the corrosion resistances of coating and substrate were compared. It is revealed that the nickel coatings prepared by pulse jet electrodeposition exhibit a fine-grained structure with a smooth surface and a high density, although some pores and defects are still present in coatings. With the increase of average current density, the average grain size of nickel coatings is reduced at first and then increased. The coating with the optimum compactness, the smallest average grain size (13.7 nm) and the highest microhardness are obtained at current density of 39.8 A/dm2. The corrosion resistance is obviously increased for the coatings prepared by pulse jet electrodeposition; however, the corrosion rate is increased after a certain period due to the penetration of the corrosive media.     

The correlation among deposition parameters,structure and corrosion behaviour of ZnNi/nano-SiC composite coating deposited by pulsed and pulsed reverse current

The present work shows how the parameters of pulsed current (PC) deposition affect structural and morphological characteristics of electrodeposited ZnNi/nano-SiC composite coating and its corrosion properties. In this regard, ZnNi coatings containing SiC nanoparticles were electrodeposited from chloride bath by PC and pulsed reverse current (PRC) methods, and the effect of duty cycle, frequency and reverse current density were studied. With low and high duty cycles the SiC content of the coating was more than the coating deposited by medium duty cycle. Changing the duty cycle affected the coating composition, structure and morphology. Elevation of the pulse frequency increased SiC content of the coating. Application of PRC produced a coating with a complex and dendritic structure. In most of the electrodeposition conditions, in addition to direct effects of PC on coatings characteristics, it was seen that the more SiC was deposited in the coating the less Ni was deposited, and this also affected the corrosion behaviour. The best corrosion resistance behaviour was shown by coatings with more compact structure and less porosity.     

Pulse electroplating of Ni-W-P coating and its anti-corrosion performance

Ni-W-P coatings were electrodeposited on copper substrates by pulse electroplating. Effects of electrolyte pH (1-3), temperature (40–80 °C), average current density (1–7 A/dm²) and pulse frequency (200–1000 Hz) on deposition rate, structure and corrosion resistance performance of Ni-W-P coatings were studied by single factor method. Surface morphology, crystallographic structure and composition of Ni-W-P coatings were investigated by means of scanning electron microscopy, X-ray diffractometry and energy dispersive X-ray spectroscopy, respectively. Corrosion resistance performances of Ni-W-P coatings were studied by potentiodynamic polarization and electrochemical impedance spectroscopy in 3.5% NaCl solution (mass fraction) and soil-containing solution. It was found that the pulse electroplated Ni-W-P coatings have superior corrosion resistance performance and the electroplating parameters significantly affect the structure and corrosion resistance performance of Ni-W-P coatings. The optimized parameters of pulse electroplating Ni-W-P coatings were as follows: pH 2.0, temperature 60 °C, average current density 4 A/dm², and pulse frequency 600 Hz. The Ni-W-P coating prepared under the optimized parameters has superior corrosion resistance (276.8 kΩ) and compact surface without any noticeable defect.     

室温离子液体中电沉积高耐蚀性Ni-Mn薄膜

目的提高AZ91D镁合金的耐腐蚀性能。方法通过电沉积方法在氯化胆碱-尿素离子液体中于镁合金表面电沉积Ni-Mn合金膜层。经过均一化前处理,在镁合金表面电沉积铜层,以提高后续Ni-Mn合金膜层与基体的结合力。利用扫描电镜(SEM)、能谱仪(EDS)、X射线衍射仪(XRD)研究了Mn元素对膜层微观形貌、成分和相结构的影响,并通过电化学方法评价了镀层的电化学腐蚀行为。结果引入Mn元素后,膜层表面微观形貌从锥状演变为肿瘤状,且Ni-Mn合金膜层的Mn含量取决于电流密度,其含量随着电流密度的增加而增加。与纯Ni膜相比,引入少量Mn元素可以提高其耐腐蚀性能,然而引入过多的Mn元素,膜层的耐腐蚀性能将弱于纯Ni膜。结论当电沉积Ni-Mn膜层含有3.078%(原子数分数)Mn时,具有最佳的耐腐蚀性能,其自腐蚀电流密度Jcorr=0.301μA/cm2,自腐蚀电位Ecorr=-0.157 V(vs.SCE)。     

Pulse-reverse electroplating of chromium from Sargent baths: Influence of anodic time on physical and electrochemical properties of electroplated Cr

Herein, chromium film was successfully synthesized by pulse-reverse (PR) electrodeposition using various anodic current time in a Sargent bath which is mainly composed of hexavalent chromium (Cr⁶⁺) and sulfuric acid (H₂SO₄). The correlation between anodic time during electroplating and various physical properties was investigated. The crack density, hardness, and thickness of electrodeposited chromium was decreased with an increase in anodic time for PR electroplating. The chromium prepared by PR electroplating showed higher corrosion resistance than that prepared by direct current (DC) electroplating owing to low crack density. Consequently, the optimal anodic time for PR electroplating was found to be 0.001 s based on the crack density, hardness, current efficiency, and film thickness. The results obtained suggest that this optimized process is a promising route for electroplating chromium film with low crack density and high corrosion resistance.     

Characterization of nanocrystalline Co–W coatings on Cu substrate,electrodeposited from a citrate-ammonia bath

Cobalt–tungsten nanocrystalline coatings were electrodeposited on copper substrate using different current densities. The deposited coatings were single phase solid solution with an average grain size of about 18 nm, showing a nodular type of surface morphology. By increasing the deposition current density, the density of nodules was increased, with no obvious variation in grain size. Electrochemical impedance spectroscopy (EIS) confirmed the codeposition of tungsten through reduction of tungsten oxide film formed during the electrodeposition process. However, the role of ternary complexes in the bath cannot be ruled out, especially at lower cathodic potentials. The Co–W coating deposited at lower current densities showed higher tungsten content, microhardness, wear resistance and friction coefficient. However, this coating showed an inferior corrosion resistance. By increasing the deposition current density, a low tungsten coating with high corrosion resistant was obtained. This is attributed to the lower value of exchange current density of water reduction in the present of oxygen (i₀^H2O) achieved on the coating with lower tungsten content.     

316不锈钢电化学着色工艺研究

    采用两步法对316不锈钢进行着色处理：先在表面冲击预镀一层镍,然后用钼酸铵进行电化学着色.研究了钼酸铵浓度、电流密度、时间和pH值对着色膜性能的影响,获得最佳工艺条件,所得黑色膜耐磨性好,光亮.采用SEM和电化学性能测试对膜的形貌,成分和耐腐蚀性能进行表征.结果表明,经着色处理后,耐蚀性能明显提高,着色膜呈块状分布,主要成分为MoO₂.     

Synthesis and properties of electrodeposited Ni-CeO_2 nano-composite coatings

Current machinery requires metallic materials to have better surface properties. Based on an orthogonal experimental design and analysis method, the CeO_2-reinforced nickel nano-composite coatings were prepared by direct current electrodeposition in a nickel sulfate bath containing CeO_2 nanoparticles. Statistical results indicate that current density is the most significant variable in the electrodeposition processing, while temperature is the least important factor. The microstructure of Ni and Ni-CeO_2 nano-composite coatings was characterized by scanning electron microscopy(SEM) equipped with energy-dispersive spectroscopy(EDS), and X-ray diffraction(XRD).The microhardness of the Ni coating is enhanced by the incorporation of CeO_2 nanoparticles. Potentiodynamic polarization and electrochemical impedance spectroscopy(EIS) were used to characterize the corrosion behavior of Ni and Ni-CeO_2 coatings. These studies show that NiCeO_2 coating has better corrosion resistance compared to Ni coating.     

Corrosion Behavior of Reverse-Pulse Electrodeposited Zn-Ni Alloys in Saline Environment

The study investigates the relationship of the reverse-pulse electrodeposited zinc-nickel alloy coatings’ characteristics and their corrosion behaviors in a saline environment, using both anodic polarization and electrochemical impedance analysis. The introduction of anodic pulsation gives deposits of more refined grain sizes and increased nickel contents, resulting in improvement of the corrosion resistance. High anodic current densities employed in the reverse-pulse electrodeposition, however, modulate crystallographic orientations of the grains, introduce porosity to the structure, and hence adversely affect the corrosion resistance of the coating deposits.