Sn/ZrO2镀层的制备及ZrO2纳米粒子对电沉积过程的影响

在酸性硫酸盐体系中，采用超声辅助电沉积制备Sn/ZrO₂复合镀层，探究了超声功率、ZrO₂纳米粒子浓度和阴极电流密度对Sn/ZrO₂复合镀层的耐蚀性影响；通过线性扫描伏安法和交流阻抗法，研究了Sn/ZrO₂体系中ZrO₂纳米粒子对电化学反应过程的影响；通过SEM和XRD分别测试镀层形貌和微观结构。实验结果表明，较优电沉积工艺为:超声功率为300 W，ZrO₂纳米粒子浓度为7 g/L，阴极电流密度为2.5 A/dm2。在较优条件下，探究纯Sn镀层和Sn/ZrO₂复合镀层电沉积过程，超声辅助纳米粒子的加入使镀层表面更加致密，增加了沉积过程活性位点，促进了Sn2+的沉积，细化了晶粒，使得镀层表面更加平整致密。      

Ni-Co/ZrO_2复合镀层的形貌与性能研究

通过超声辅助复合电沉积方法在氨基磺酸盐体系中制备了Ni-Co/ZrO_2复合镀层。采用单一变量法探讨了电流密度、ZrO_2粉体质量浓度和超声功率对电沉积Ni-Co/ZrO_2复合镀层硬度的影响,优化了Ni-Co/ZrO_2复合镀的工艺参数;对镀层进行了纳米压痕测试,并采用场发射扫描电子显微镜表征优化后Ni-Co/ZrO_2复合镀层的形貌和成分。研究结果表明,优化的电沉积工艺参数为:阴极电流密度5A/dm~2,ZrO_2粉体质量浓度10g/L,超声功率240W。在此条件下,Ni-Co/ZrO_2复合镀层的纳米硬度、弹性模量以及硬模比分别达到6.13GPa、291GPa和0.021,镀层平整致密,ZrO_2纳米粒子较好地复合于金属基质中。     

超声辅助电沉积Ni-Co/ZrO_2复合镀层的性能研究

采用超声辅助电沉积方法将Ni-Co/ZrO_2纳米复合镀层电镀到铜板表面。在不同纳米粒子添加量下,通过线性扫描伏安(LSV)和交流阻抗(EIS)对电沉积过程进行电化学表征,通过SEM、EDS对镀层的组成和表面形貌进行研究,并分别利用显微硬度计和摩擦磨损试验仪对复合镀层的力学性能和摩擦磨损性能进行表征。结果表明,超声的引入能够有效降低镀液中颗粒的团聚量,提高镀层中纳米粒子的复合量,从而改善复合电沉积过程以及镀层性能。在纳米粒子浓度为10g/L时,镀层的表面形貌、摩擦性能和硬度等性能最优。     

镍基与铜基碳化硅复合镀层制备技术发展现状

碳化硅(SiC)纳米复合镀层可以改善材料的耐磨性能,是代硬铬电镀的理想替代技术,本文对SiC复合电镀广泛使用的Ni基及Cu基复合电沉积制备工艺在耐磨方面的应用进行了概述,对Ni、Cu单金属及其合金为主的基质金属进行了评价和总结,在此基础上,重点综述了近年来SiC复合电沉积技术的研究进展,包括单一SiC颗粒及与其他复合颗粒沉积,对其中的规律进行了总结。最后展望了SiC复合电沉积技术的发展方向。     

ZrO_2含量与占空比对Ni-Co-ZrO_2复合镀层显微组织及耐蚀性的影响

以硫酸镍(Ni_SO4·6H_2O)、硫酸钴(CoSO_4·7H_2O)和氧化锆(ZrO_2)为主要原料,采用脉冲电沉积法在Q235钢基体表面制备了Ni-Co-ZrO_2复合镀层,通过扫描电镜和能谱仪分别分析了复合镀层的显微形貌及成分组成,并对Ni-Co-ZrO_2复合镀层的耐蚀性进行了研究。结果表明:镀层组织均匀、致密,与基体之间无裂纹、气孔等缺陷;ZrO_2颗粒弥散分布于Ni-Co合金基体中,随着ZrO_2颗粒的嵌入,Ni-Co合金的晶粒形貌由针状向菜花状转变;沉积1.5h后,镀层厚度约60μm,且镀态条件下Ni-Co-ZrO_2复合镀层为晶态结构;随着镀液中ZrO_2颗粒浓度增大及占空比降低,Ni-Co合金晶粒得到细化,复合镀层的耐蚀性显著提高,当ZrO_2含量为20g/L、占空比为40%时,复合镀层的耐蚀性最佳。     

脉冲占空比对电沉积Sn-Ni-Mn合金镀层的影响

研究采用脉冲电沉积法在Q235钢表面制备Sn-Ni-Mn合金镀层,利用辉光放电光谱仪(GDS)、扫描电镜(SEM)、Tafel曲线和电化学阻抗谱(EIS)考察了脉冲占空比对镀层元素含量、沉积速率、表面形貌、阴极电流效率和耐蚀性的影响。结果表明:随占空比增大,镀层中Ni、Sn含量升高,Mn含量降低,镀层沉积速率减小,阴极电流效率先升高后降低,镀层耐蚀性先增强后减弱;占空比为0.2时,所制备的Sn-Ni-Mn合金镀层均匀致密,在3.5%NaCl溶液中具有最正的自腐蚀电位(-0.377V),最低自腐蚀电流密度(3.687×10~(-8) A·cm~(-2))和最大电荷转移电阻(7 658Ω·cm~2),耐蚀性最好。     

电沉积制备Ni-Co-Al_2O_3纳米复合镀层的研究

采用电沉积工艺制备了Ni-Co-Al2O3纳米复合镀层,利用显微硬度仪测定了复合镀层的硬度,考察了电流密度、纳米Al2O3浓度、电镀温度及镀液pH对镀层硬度的影响,分别借助SEM分析技术及电化学测试技术对最大硬度镀层进行微观性能及耐蚀性能进行研究。结果表明,纳米Al2O3弥散分布在镀层中,复合镀层晶粒进一步细化,耐蚀性显著提高。     

超声波对Ni-Co-Al_2O_3镀层性能的影响

采用超声电沉积法在纯铜表面成功制备出性能良好的Ni-Co-Al2O3复合镀层,并讨论了超声波对镀层性能的影响机理。结果表明,在适当的超声功率下,超声波主要是通过空化效应、射流效应等影响提高镀层的沉积速率、硬度及耐蚀性;当超声功率过高时,超声波无益于提高镀层性能。     

氧化物熔盐电沉积二硼化钛镀层的研究

分别采用脉冲电源和直流电源,利用TiO2 B2 O3 LiF KF熔盐体系,在石墨基体上电沉积制备了TiB2 镀层。在实验中,考察了直流电流密度、脉冲宽度、脉冲间隔、脉冲电流幅度等条件对TiB2 镀层性能的影响。实验结果表明:采用脉冲电沉积得到的镀层性能优于直流电沉积。在本实验参数下(摩尔比TiO2 ∶B2 O3∶KF∶LiF =0 .0 6∶0 .4∶0 .74∶0 .8,温度80 0℃,脉冲宽度7.5ms ,脉冲间隔2 .5ms,电流密度0 .6A·cm- 2 ,电沉积时间5 0min)得到的TiB2 镀层表面平整,有金属光泽,结构致密,晶粒细小,与基体的结合力良好。     

Ni-Co/ZrO_2复合镀层的电化学研究和性能表征

在酸性氨基磺酸盐溶液体系中,采用共沉积技术制备Ni-Co/ZrO_2复合镀层。通过阴极线性扫描测试,研究了Ni-Co/ZrO_2复合体系中纳米粒子对电化学反应过程的影响;通过SEM、XRD测试分别研究了复合镀层的表面形貌和微观结构;通过Tafel曲线测试镀层的耐蚀性能,通过退火后的显微硬度测试表征镀层的热稳定性能。试验结果表明:Ni-Co/ZrO_2共沉积电位大约为-0.90V;与Ni-Co合金相比,Ni-Co/ZrO_2复合镀层表面更加均一致密,晶粒更加细小,耐蚀性和热稳定性更好。     

Characteristics and properties of Cu/nano-SiC and Cu/nano-SiC/graphite hybrid composite coatings produced by pulse electrodeposition technique

In this study, Cu/SiC and Cu/SiC/graphite nano-composite coatings were prepared by using pulse current electrodeposition technique. The effects of pulse parameters and graphite particles concentration of the bath on co-deposition of these particles were investigated. Morphology, composition, structure, microhardness, tribological behaviour and corrosion properties of Cu/SiC/graphite coatings were studied and compared to those of the substrate and Cu/SiC films. The results revealed that the optimum current density, pulse frequency and duty cycle for obtaining the highest graphite content within the coatings were 12?A?dm^?2, 15?Hz and 5%, respectively. According to X-ray diffraction results, all the coatings had face-centred cubic structure, but with different preferred orientations. While Cu/SiC coatings had higher hardness and corrosion resistance than the Cu/SiC/graphite hybrid composites, the lowest wear rate was obtained at Cu/6.8vol.-% SiC/6.7vol.-% graphite hybrid composite film.     

Probe into deposition mechanism of double pulse electrodepositing Ni-W-P matrix composite coatings containing CeO₂ and SiO₂ nano-particles

Ni-W-P matrix composite coatings reinforced by CeO2 and SiO2 nano-particles were prepared on common carbon steel surface by double pulse electrodeposition and the deposition mechanism was discussed.The results showed that the composite coatings with amorphous structure were obtained as-deposited.The initial growth behavior had alternatives and the nucleation was inhomogeneous because of obvious composition fluctuation.With the pulse deposition time increasing,some pearlite microstructures of the substrate were covered by some deposits and the composition fluctuation disappeared.Forward pulse currents promoted to form a great number of atomic beams composed of Ni,W and P atoms or CeO2 and SiO2 nano-particles as the core,which inhabited the growth of atomic beams.Reverse pulse currents eliminated concentration polarization and dissolved some surface boss of atomic beams.The solution of W and P atoms within Ni grains and embedding of CeO2 and SiO2 nano-particles within Ni-W-P matrix metal made atomic arrangement disordered.Finally,the atomic beams grew to amorphous small particles.     

Study on Anticorrosive Cerium Conversion Coating of Cf/6061Al Composite Surface

The optimum chemical passivation process of the rare earth metal (REM) conversion coating on the Cf/6061Al composite surface was introduced in this paper and its polarization curves properties were investigated. Ridge-like coatings were found by scanning electro microscope (SEM) observations, and the Al matrix and carbon fibre reinforcement were both coated with Ce conversion coatings, with some minor cracks. The energy dispersive spectroscopy (EDS) plane scan analysis indicates that the major elements in the coating are Ce, O, Si, Al and the Ce content reaches 47.48%(mass fraction). The Ce conversion coatings increase the corrosion resisting properties of Cf/6061Al composite, with a higher free corrosion potential (Ecorr) and a lower free corrosion current density (icorr) for the coated composite than those of the bare composite. And the Boehmite-treatment would enhance the corrosion resistance of the REM conversion coating. The cathodic polarization and anodic polarization were retarded by REM conversion coating, resulting in an improved corrosion resistance.     

Fabrication and Characterization of Ni-SiC Nanocomposite Coatings on Al Substrates by Ball Impact Deposition Method

Micron-size Ni and SiC powder mixtures were used to prepare Ni-SiC nanocomposite coatings on an Al substrate by employing a high-energy ball milling technique. Ni:SiC weight ratio was varied over a wide range to explore the effect of the charge composition on the microstructure, composition, microhardness, and wear properties of the depositions. It was observed that the composition of the produced coating was correlated to the charge composition in a complex manner, which suggests that deposition rates for Ni and SiC particles significantly vary depending on the charge composition; SiC deposition rate was higher than that of Ni when Ni:SiC weight ratio was greater than 3:1. Diffusion of Al from the substrate into the Ni matrix provided evidence for the metallurgical bonding at the interface. Both microstructural and mechanical properties of the produced coatings were found to be crucially dependent on the charge composition. By increasing the SiC content in the charge from about 5 to 33 wt pct, the mechanical properties enhanced due to the dispersion strengthening effect of the incorporated SiC particles in the coatings and the crystallite size of the Ni matrix decreasing to the nanometer range. However, a further increase resulted in the formation of a coating with a poor degree of compaction. It was found that the composite coating with about 15 vol pct SiC, produced from the charge with Ni:SiC weight ratio of 2:1, showed a microhardness as high as 830 HV_0.05 along with excellent wear resistance. Despite the current sample size limitations for applying high-energy ball milling, the present findings demonstrate that the adopted technique holds good prospect for the synthesis of nanostructured metal matrix composite coatings with enhanced and tunable properties.

     

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.     

镍磷合金碳化硅复合镀层的制备与磨损性能研究

采取化学沉积方法，获得镍磷合金碳化硅复合材料镀层，研究了复合镀层的构成与磨损性能。研究结果表明，镍磷合金中加入碳化硅，不会影响其组织结构，但会显著地提高硬度和耐磨性；复合镀层经过热处理，组织结构发生变化；６７３Ｋ／１ｈ处理后，硬度与耐磨性最高，较镍磷合金镀层具有更高的硬化性能。     

Probe into deposition mechanism of double pulse electrodepositing Ni-W-P matrix composite coatings containing CeO2 and SiO2 nano-particles

Ni-W-P matrix composite coatings reinforced by CeO₂ and SiO₂ nano-particles were prepared on common carbon steel surface by double pulse electrodeposition and the deposition mechanism was discussed. The results showed that the composite coatings with amorphous structure were obtained as-deposited. The initial growth behavior had alternatives and the nucleation was inhomogeneous because of obvious composition fluctuation. With the pulse deposition time increasing, some pearlite microstructures of the substrate were covered by some deposits and the composition fluctuation disappeared. Forward pulse currents promoted to form a great number of atomic beams composed of Ni, W and P atoms or CeO₂ and SiO₂ nano-particles as the core, which inhabited the growth of atomic beams. Reverse pulse currents eliminated concentration polarization and dissolved some surface boss of atomic beams. The solution of W and P atoms within Ni grains and embedding of CeO₂ and SiO₂ nano-particles within Ni-W-P matrix metal made atomic arrangement disordered. Finally, the atomic beams grew to amorphous small particles.     

低烧损 复合粉末制备及涂层抗烧蚀性能研究

采用喷雾造粒-胶粘包覆的方法制备了一种低烧损核壳结构 ZrB2/SiC 复合粉末, 研究了胶粘包覆过程中不同清漆含量对粉末包覆效果的影响。 结果表明清漆含量不足时细粉包覆不完全, 细粉出现单独团聚的现象; 清漆含量过多时, 造成原始球形颗粒的粘连; 当清漆含量为 4.5% 时, 获得包覆效果良好的粉末, 外层包覆完整均 匀。 为了研究等离子喷涂过程中核壳结构粉末 SiC 发生分解烧损程度, 对比了分别采用核壳结构和均匀弥散结构ZrB2/SiC 复合粉末所制备涂层的微观形貌及涂层中元素分布。 结果表明核壳结构粉末喷涂涂层成分均匀性良好,高熔点 ZrB2 保护内层 SiC, 可有效减少 SiC 在等离子焰流中的烧损, 实现涂层和粉末成分的一致性。 对核壳结构复合粉末制备的涂层进行了 20s 的氧-乙炔火焰烧蚀试验, 涂层质量烧蚀率为 1.837×10-3g/s, 对涂层抗烧蚀机理进行了初步探讨。     

超音速火焰喷涂制备Cr2AlC涂层组织性能研究

采用真空分段烧结法制备了两种不同粒度的高单相Cr2AlC化合物粉末,并使用超音速火焰喷涂(HVOF)方法在GH4169高温镍合金上制备了Cr2AlC涂层,对喷涂粉末及涂层进行了相结构分析,测试了涂层的显微硬度、孔隙率,并采用扫描电子显微镜(SEM)对喷涂粉末及涂层截面形貌进行了观察,结合扫描电镜能谱仪(EDS)和X射线衍射研究了涂层相组成,分析了粉末粒度对涂层微观组织结构的影响。研究结果表明:采用超音速火焰喷涂成功制备了厚度超过200μm的Cr2AlC涂层,涂层与基体紧密结合,涂层微观组织致密,采用较细的粉末有利于得到更高致密度的涂层。在喷涂过程中,有少量Cr2AlC粉末发生分解形成Cr7C3化合物。