脉冲换向电刷镀镍基纳米SiO2复合镀层的耐腐蚀性能研究

采用脉冲换向电刷镀方法制备了Ni/n-SiO2复合镀层,应用SEM对镀层表面形貌进行了分析,测试了镀层的孔隙率,以及镀层在海水浸泡条件下的耐腐蚀性能,讨论了镀层的耐腐蚀机理.实验结果表明:与直流工艺条件下的电刷镀镀层相比,脉冲换向电刷镀工艺得到的Ni/n-SiO2复合镀层具有致密精细的表面、较小的孔隙率和较高的耐腐蚀性能.     

脉冲换向电刷镀Ni/n-Al2O3复合镀层的耐腐蚀性能研究

利用脉冲换向电刷镀方法制得了Ni/n-Al2O3复合镀层,对其表面形貌(SEM)进行了观测和分析,测试了镀层的孔隙率,并通过海水浸泡法检测其耐腐蚀性能,并与其他工艺条件下的电刷镀镀层进行比较,结果发现,采用脉冲换向电刷镀工艺得到的Ni/n-Al2O3复合镀层具有致密精细的表面形貌、较小的孔隙率和较好的耐腐蚀性能。     

电刷镀Ni／n-SiO2复合镀层的形貌及摩擦学性能研究

利用脉冲换向电刷镀方法制得了Ni／n—SiO2复合镀层，并对镀层进行了表面形貌观察和分析，测试了镀层的摩擦学性能，与直流工艺条件下的快镍镀层和Ni／n—SiO2复合镀层相比，采用脉冲换向电刷镀工艺得到的Ni／n—SiO2复合镀层，由于脉冲换向电流的细晶强化作用和纳米颗粒的弥散强化作用，镀层致密、晶粒团尺寸细小、硬度高、摩擦系数低，因此耐磨性能更好。     

电沉积方式对Ni-SiC纳米复合镀层性能的影响

目的通过研究电沉积方式对Ni-SiC纳米复合镀层性能的影响,进而改善Ni-SiC纳米复合镀层的性能。方法采用直流电沉积和脉冲电沉积分别制备Ni和Ni-SiC纳米复合镀层,使用扫描电镜和能谱仪研究镀层的表面形貌和成分,通过测量施镀前后镀件质量差计算沉积速率,采用硬度计测量了镀层的硬度,利用极化曲线和电化学阻抗方法研究镀层在3.5%NaCl水溶液中的耐腐蚀性能,分析了直流电沉积方式和脉冲电沉积方式对镀层各项性能的影响。结果脉冲电沉积方式制备的Ni-SiC纳米复合镀层的表面形貌更加致密、均匀、光滑,镀层硬度为616.3HV,自腐蚀电流为9.56×10~(-6) A,比直流电沉积制备的Ni-SiC纳米复合镀层的硬度和耐蚀性能均有所提高。结论电沉积方式对复合镀层的性能有很大影响,脉冲电沉积方式制备的Ni-SiC纳米复合镀层具有更好的性能。     

脉冲电沉积WC-Co-Ni镀层的制备及性能研究

目的提高WC-Co-Ni纳米晶复合镀层的综合性能。方法利用脉冲电沉积法制备WC-Co-Ni纳米晶复合镀层,分析镀层的结构、表面形貌及元素成分,测试镀层的显微硬度。对WC-Co-Ni纳米晶复合镀层和304不锈钢进行5%(质量分数)H2SO4溶液浸泡实验,计算腐蚀速率,对比其耐蚀性。结果当脉冲参数为阴极电流密度5 A/dm2、脉冲占空比50%、脉冲频率2000 Hz时,施镀2 h制备的WC-Co-Ni复合镀层为纳米晶结构。镀层表面平整、光亮,无裂纹,由立方晶型的Ni、六方结构的WC和立方晶型的Co组成,WC-Co颗粒均匀弥散在纳米晶Ni镀层内,且m(Ni)∶m(W)∶m(C)∶m(Co)=6∶2∶1∶1。WCCo纳米颗粒起到了促进形核的作用,晶粒尺寸大多分布在20 nm左右。WC-Co纳米颗粒对镀层起到了弥散强化作用,使复合镀层的显微硬度达到600HV。在浸泡腐蚀实验中,随着温度从20℃升高至80℃,复合镀层的腐蚀速率增加缓慢,20℃下的腐蚀速率仅为0.4192 mm/a,80℃下的腐蚀速率也低于20mm/a。结论脉冲电沉积法制备的WC-Co-Ni纳米晶复合镀层硬度高于传统的不锈钢材料,耐蚀性也优于304不锈钢,综合性能较好。     

换向脉冲喷射电沉积制备Co-Cr3C2复合镀层的工艺探讨

目的：有效解决利用喷射电沉积在直流电流下制备的复合镀层存在的镀层表面粗糙,尤其当硬质颗粒尺寸达到微米级时,表面恶化程度尤为严重的问题。方法将换向脉冲电流取代直流电流应用于喷射电沉积,制备颗粒尺寸达到微米级的Co-Cr3C2复合镀层,通过分析复合镀层组织形貌、硬度和耐磨性等,探讨换向脉冲电参数对复合镀层颗粒复合量、镀层表面粗糙度以及镀层性能的影响,并对其影响机理进行分析。结果在保持颗粒较高含量复合的同时提高镀层表面平整度,通过控制脉冲电参数,制备出复合微米级Cr3C2颗粒平整、颗粒质量分数为11%的Co-Cr3C2复合镀层。结论 Cr3C2颗粒的复合量越高,镀层性能越优异,但镀层表面也更加粗糙,换向脉冲电流的反向过程可发生共沉积的逆过程,利用脉冲电流不仅对复合镀层起到整平的作用,同时可以提高颗粒在复合镀层中分散的均匀性,使复合镀层的表面形貌以及性能均得到明显改善。     

纳米TiC浓度对双脉冲电沉积Ni-TiC复合镀层结构及性能的影响

研究了镀液中纳米TiC的添加量对双脉冲电沉积Ni-TiC复合镀层结构及性能的影响。通过扫描电镜(SEM)和X射线衍射(XRD)对镀层的表面形貌和物相进行了表征,并研究了镀层的表面粗糙度、显微硬度、耐磨性能和耐腐蚀性能。结果表明：当镀液中TiC浓度较低时,复合镀层表现为类似于纯Ni镀层的胞状沉积结构。当镀液中TiC浓度较高时,复合镀层表现为菜花状沉积结构。当纳米TiC浓度为8 g/L时,镀层表面致密性相对较高,Ni的衍射峰有明显的宽化现象。随着镀液中纳米TiC浓度的升高,复合镀层的磨损质量损失比表现为先下降后上升的趋势,当TiC浓度为8 g/L时,磨损质量损失比最小,为5.436%。当镀液中纳米TiC浓度为8 g/L时,镀层的自腐蚀电流密度最小,极化电阻值最大。结果表明双向脉冲电沉积制备Ni-TiC复合镀层镀液中最佳纳米TiC浓度为8 g/L。     

低共熔溶剂中电化学剥离制备GO及脉冲电沉积Ni-GO复合镀层性能研究

目的在低共熔溶剂中实现电化学剥离制备氧化石墨烯(GO)及电沉积制备Ni-GO复合镀层,提高Ni镀层的耐腐蚀和摩擦磨损性能。方法以石墨棒为阴极,铂片为阳极,低共熔溶剂为电解液,采用直流电源电化学剥离石墨制备氧化石墨烯纳米片(GO),然后在此电解液中,采用脉冲电沉积的方式制备Ni-GO复合镀层。采用扫描电子显微镜(SEM)、透射电子电镜(TEM)、紫外分光光度计(UV)、红外光谱仪(IR)、拉曼光谱仪(Raman)、X射线衍射仪(XRD),表征GO的结构和组成。采用扫描电子显微镜(SEM)观察镀层的表面形貌,采用X射线衍射仪(XRD)、X射线光电子能谱仪(XPS)分析镀层的结构特征。采用电化学工作站、纳米压痕仪和摩擦磨损实验机分析镀层的耐腐蚀性能、机械性能和摩擦磨损性能。结果采用电化学剥离法在低共熔溶剂中成功制备了GO,GO呈现大的片层状结构,表面存在褶皱,边缘弯曲,上下表面层含有大量羟基和环氧基。性能检测表明,Ni-GO复合镀层的腐蚀电流密度由纯Ni镀层的6.10×10^-5 A/cm^2降低为5.78×10^-7 A/cm^2,硬度由纯Ni镀层的(8.95±0.43)GPa提高到(13.75±0.75)GPa,弹性模量由纯Ni镀层的(184.55±8.12)GPa提高到(201.38±11.20)GPa,摩擦系数由纯Ni镀层的0.72降低为0.56,磨损率比纯Ni镀层降低了35.16%。结论在低共熔溶剂中实现了电化学剥离石墨制备GO,并用于Ni-GO金属基复合镀层一步制备的电化学途径,为均匀分散的氧化石墨烯的制备和金属基复合镀层的制备提供了新的方法。以此为电解液制备的Ni-GO复合镀层相比于纯Ni镀层,其晶粒细化,耐腐蚀性能增强,机械性能提高,摩擦系数减小,耐磨性能增强。     

脉冲关断时间对电刷镀Ni/CNTs复合镀层组织及性能的影响*

采用脉冲电刷镀的方法,制备了镍/碳纳米管（Ni/CNTs）复合镀层.运用扫描电子显微镜（SEM）、X射线能谱分析仪（EDS）、透射电子显微镜（TEM）、球盘式磨损试验机、显微硬度计等分析与测试方法,研究了脉冲关断时间对Ni/CNT复合镀层的表面形貌、孔隙率、CNTs含量、显微硬度和耐磨性等的影响.结果表明：在直流电源下,由于导电性和准一维性碳纳米管的共沉积,复合镀层表面粗糙,孔隙率高.采用脉冲电源后,当脉冲关断时间增加至1 900μs时,复合镀层的表面平整度增加、孔隙率减小为1%、硬度增加为605 HV、磨损重量减小1/3.     

脉冲电沉积高速Ni工艺研究

研究了高速Ni镀液在脉冲电沉积条件下,工艺参数对Ni镀层的沉积速率、内应力、孔隙率及微观形貌等方面的影响规律。结果表明,温度、平均电流密度、频率、逆向脉冲系数及占空比对镀层性能和微观形貌有较大影响。与常规电沉积Ni方法相比,脉冲电沉积高速Ni还具有高效、节能等特点。     

Electrodeposition of multi-layer Pd–Ni coatings on 316L stainless steel and their corrosion resistance in hot sulfuric acid solution

Pd–Ni coating shows good corrosion resistance in strong corrosion environments. However, in complex aggressive environments, the performance of the coatings is limited and further improvement is necessary. The effects of the applied plating current density on the composition, structure and properties of Pd–Ni coatings were studied. By changing the current density in the same bath, multi-layer Pd–Ni coatings were prepared on 316L stainless steel. Scanning electronic microscopy, weight loss tests, adhesion strength, porosity and electrochemical methods were used to study the corrosion resistance of the films prepared by different coating methods. Compared with the single layer Pd–Ni coating, the multi-layer coatings showed higher microhardness, lower internal stress, lower porosity and higher adhesive strength. The multi-layer Pd–Ni coating showed obviously better corrosion resistance in hot sulfuric acid solution containing Cl^?.     

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.     

热浸Zn-Ti合金镀层的耐腐蚀性能

为了抑制热镀锌过程中因含硅活性钢引起的镀层超厚生长,采用在纯锌浴中加Ti的方法,研究了热浸Zn-Ti合金镀层的耐蚀性能.采用浸泡腐蚀、电化学极化、交流阻抗以及X射线光电子能谱等方法,研究了热浸Zn-Ti合金镀层的耐蚀性能.结果表明:Zn-Ti舍金镀层在5%NaCl溶液中的自发腐蚀倾向小于Zn镀层,其极化电阻和交流阻抗增大,腐蚀电流密度减小,耐蚀性能提高.Zn-Ti镀层表面形成的氧化膜由ZnO和TiO2组成.Zn-Ti合金镀层的耐腐蚀性能优于纯锌镀层是由于在镀层表面形成了更加稳定的TiO2膜.     

Effect of current density on micro‐arc oxidation of Q235 steel and corrosion resistance in liquid Pb‐Bi

An attempt has been made to improve the corrosion resistance in liquid Pb‐Bi by micro‐arc oxidation (MAO), and the effects under different current densities on the corrosion resistance of the coatings were discussed. Scanning electron microscope, energy dispersive spectrometer, and X‐ray diffraction were used to analyze the surface morphology and phase constituents of the MAO coatings produced under different current densities. The corrosion resistance of the coatings was evaluated by studying the element changes and morphology evolution. The results show that the compactness of the ceramic coating decreases with the current density increasing. In contrast to the performance of matrix metal, the ceramic coating exhibited a much better corrosion resistance in liquid Pb‐Bi. Moreover, the ceramic coating produced under current density of 10 A/dm ² shows the best corrosion resistance.     

The effects of pulse-reverse parameters on the properties of Ni-carbon nanotubes composite coatings

A nickel based composite coatings reinforced with carbon nanotubes (CNTs) were prepared by pulse-reverse electrodeposition. The effects of reverse ratio and frequency on the surface morphology, micro-hardness and corrosion resistance of Ni-CNTs composite coatings were studied. The results showed that higher pulse reverse ratio and pulse frequency made the surface morphology of the coatings more homogeneous. The micro-hardness of the coatings increased with the increase of reverse pulse ratio but decreased with the increase of pulse frequency. Corrosion resistance of the coatings first increases then decreases as the pulse frequency and reverse ratio increase. The best corrosion resistance was obtained for coatings under the condition of 30% reverse ratio and 100 Hz pulse frequency. The effects of CNTs on the properties of the composite coatings were discussed.     

高速电喷镀纳米复合镀层组织与性能研究

采用高速电喷镀工艺制备纳米Ni／PTFE复合镀层。研究了电流密度、镀液中纳米PTFE含量等工艺参数对镀层性能的影响。研究结果表明，提高电流密度可显著提高复合镀层的沉积速率、镀层与基体的结合强度以及镀层的耐腐蚀性：镀层与基体的结合强度随镀液中PTFE的加入量的改变而变化，当加入量为10ml／L时，镀层经30次热震试验后，镀层无明显剥落：Ni与纳米PTFE共沉积可显著改善镀层的耐腐蚀性能。     

Corrosion resistance of Zn–Ni/Ni and Ni/Zn–Ni compositionally modulated multilayer coating

Zn–Ni/Ni and Ni/Zn–Ni compositionally modulated multilayer (CMM) coatings were prepared by dual‐bath technique. The effects of layers number and sublayers order were studied. Specially, the effect of different sublayers thickness ratios with the same multilayer period (λ) on the corrosion resistance of the CMM coatings was investigated in detail. Results showed that the corrosion resistance of Ni/Zn–Ni (Zn–Ni alloy sublayer as the top layer) CMM coating was better than that of Zn–Ni/Ni (Ni sublayer as the top layer) CMM coating. The 6‐layer CMM coating with the layer thickness ratio of Ni/Zn–Ni = 0.8:1.2 (λ = 2 µm) has the best corrosion resistance.