糖精钠对电沉积纳米晶镍层组织结构及性能的影响

采用脉冲电沉积法制备纳米晶镍镀层,利用扫描电镜、透射电镜及XRD对不同糖精钠浓度下制得的镍镀层的微观结构进行了表征,采用显微硬度计、DSC及全电位测试仪对镀层的硬度、热稳定性和耐蚀性进行研究.结果表明:镍镀层晶粒尺寸随着糖精钠浓度升高先增后降,浓度为10 g/L时晶粒尺寸最小;当浓度低于15 g/L时,镀层表面较为光滑、明亮;镍镀层的显微硬度在糖精钠浓度为10 g/L时达到最大值,显微硬度与平均晶粒尺寸的关系基本符合Hall-Petch方程;镍层晶粒的失稳长大温度随糖精钠浓度的增加在305℃上下波动;当糖精钠浓度为10 g/L时,镍层的耐蚀性最好.     

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.     

Influence of Pulse Electrodeposition and Heat Treatment on Microstructure,Tribological, and Corrosion Behavior of Nano-Grain Size Co-W Coatings

In the present study, Co-W nano-structured alloy coatings are produced on low-carbon steel substrate by means of pulse electrodeposition from a citrate-based bath under different average current densities and duty cycles. The results indicate that the coating deposited under 60% of duty cycle and 1 A/dm² of average current density exhibit optimum pulse plating conditions with 44.38 wt.% W, 37 nm grain size, and 758 HV microhardness. The effect of heat treatment temperature on microstructure, composition, corrosion behavior, and morphology of amorphous deposited Co-W alloy with 44 wt.% W was investigated. The microhardness of the coating increased to 1052 HV after heat treatment at 600 °C, which is due to the formation of Co₃W and CoWO₄ phases in the deposit. Furthermore, the coatings heat-treated at 600 °C had lower friction coefficients and better wear resistance under various loads than before heating.     

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.     

纳米Cr2O3复合电刷镀镀层性能研究

在快速镍镀液的基础上,通过添加纳米Cr2O3粉末得到了纳米复合镀液,制备了纳米Cr2O3颗粒的镍基复合镀层,通过显微硬度、孔隙率、耐腐蚀与极化曲线、SEM等测试手段,比较了纳米复合镀层与纯镍镀层的性能,结果表明：纳米Cr2O3复合刷镀镍层的截面硬度比纯镍镀层的截面硬度提高8.3%,两种镀层与基体结合良好;纳米Cr2O3复合镀层的表面形貌比纯镍镀层更加细化且耐腐蚀性有所提高。     

粒径对电沉积Ni-SiC复合镀层性能的影响

采用复合电沉积的方法,在一定的工艺条件下制备出Ni-SiC复合镀层。通过摩擦磨损试验、电化学腐蚀试验,并利用扫描电镜观察镀层的磨损和腐蚀形貌,综合分析了SiC颗粒大小对镀层性能的影响。结果表明：当SiC粒径为2μm,添加量为60 g.L-1时,镀层的显微硬度最高,耐磨性能最佳;复合镀层的耐蚀性比纯镍镀层和钢基体优越,但随着SiC粒径的增大,镀层的耐蚀性反而有所下降。     

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。     

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     

直流与脉冲电沉积Ni-Cr合金镀层的结构及耐蚀性

用直流电沉积(DC)、脉冲电沉积(PC)技术在低碳钢表面制备Ni-Cr合金镀层,采用X射线衍射(XRD)、扫描电镜(SEM)、原子力显微镜(AFM)等方法,研究了电沉积方式对合金镀层晶粒结构和表面形貌的影响;用浸泡法和电化学极化法测试了合金镀层在3.5%(质量分数)Na Cl溶液中的耐蚀性。结果表明,电沉积方式对镀层结构和性能有较大影响:PC方式得到的合金镀层,其纳米晶尺寸更小(由45 nm减小为26 nm),镀层表面致密性更高;表现在性能上,与DC相比,PC合金镀层的显微硬度更大(由7000 MPa增加到8250 MPa),耐蚀性更好(自腐蚀电位由–0.624V正移到–0.477 V,腐蚀电流密度由1.911×10~(-4)A/cm~2减小到2.587×10~(-5) A/cm~2)。     

石墨烯颗粒对Ni-Co-石墨烯复合镀层的表面性能影响

为了得到性能更加优异全面的复合镀层,使用复合电沉积技术制备不同石墨烯颗粒大小的Ni-Co-石墨烯复合镀层,并制备了Ni-Co合金镀层。测试镀层的表面形貌,相结构,显微硬度,耐磨性和耐蚀性能。结果显示,石墨烯在电沉积中很好的嵌入到了镀层基质中,而且石墨烯的存在并没有改变镀层基质的晶体结构;石墨烯的填加增加了复合镀层的显微硬度,最高可达805HV;降低了复合镀层的摩擦系数,在一定程度上减少了粘着磨损的面积;复合镀层的自腐蚀电流密度可以降低到1.0905×10-5A/cm2,低于Ni-Co合金镀层的自腐蚀电流密度。说明了石墨烯的添加增强了复合镀层的硬度,耐磨性和耐蚀性。     

无氰电镀液中超声电沉积耐腐蚀纳米晶铜镀层

通过超声辅助电沉积法,在无氰络合电镀液中以高阴极电流密度在钕铁硼磁体上电沉积获得纳米晶铜防护镀层,研究了不同超声波频率下的镀层形貌、晶粒尺寸、显微硬度和耐腐蚀性能。结果表明,随着超声波频率的增加,络合电镀液体系的铜电沉积有效阴极电流密度显著增加,相应的阴极电流效率也提高,从而获得致密的纳米晶铜镀层。在阴极电流密度为4.0 A·dm^-2和超声波频率为40 kHz的条件下,能够获得平均晶粒尺寸为18.8 nm的铜镀层。超声辅助电沉积法还能促进烧结钕铁硼基体盲孔内的铜沉积,从而改善基体与镀层之间的结合力。在同样的镀层厚度下,烧结钕铁硼表面所沉积镀层的耐腐蚀性随超声波频率的提高而优化。     

超声条件下脉冲电镀 Ni-纳米 Al2 O3 复合镀层及其显微硬度研究

目的优选脉冲参数,以获得具有较高显微硬度的复合镀层。方法超声条件下,采用脉冲电镀方法制备Ni-纳米Al2O3复合镀层。以显微硬度作为性能指标,对比考察平均电流密度、占空比、频率和施镀时间的影响。结果 Ni-纳米Al2O3复合镀层的显微硬度随着平均电流密度升高,占空比增大,频率升高,均呈现出先增后减的趋势,而随着施镀时间延长,呈现出近似递减的趋势。结论在平均电流密度8 A/dm2、占空比0.6、频率1.5 k Hz、施镀时间3 min的条件下,制备的Ni-纳米Al2O3复合镀层显微硬度最高,约为427.1HV。较高复合量的纳米微粒有效起到了弥散强化和细晶强化作用,改善了复合镀层结构致密程度,进而提高了显微硬度。     

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。     

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。     

电沉积制备Ni/nano-WC复合镀层的工艺及机理研究

采用脉冲电沉积法制备了纳米WC强化镍基复合镀层。探究了不同表面活性剂（十二烷基硫酸钠）添加量以及WC粉的湿磨预处理对Ni/nano-WC复合镀层表面形貌、颗粒分布、微观结构以及显微硬度的影响。表面活性剂的添加和对WC湿磨处理有助于细化镀层晶粒,得到WC颗粒分布均匀的致密镀层。镀层中WC含量以及镀层的显微硬度随着表面活性剂的添加量的增加而增加,但过量会使效果变差,理想的SDS添加量为0.15g/l,湿磨10h。     

不同活化工艺对电解镍始极片结合力及性能的影响

目的为了提高电解镍始极片与基体的结合力,增加镀层耐蚀性能,改善镀层质量。方法通过采用不同的活化工艺对基体进行表面处理后制备镀层,采用划格法测试镀层与基体的结合力,用场发射电子扫描显微镜观察镀层与基体的截面形貌,用X射线衍射仪(XRD)分析镀层的相组成、应力以及镀层晶粒尺寸大小,用电化学工作站研究镀层的耐蚀性能。结果基体经过活化工艺处理后,镀层与基体结合均匀、致密、完整,大幅提高了镀层与基体的结合力,改善了镀层质量,镀层内应力由287.2 MPa降低到220.0 MPa,并且活化工艺不会给镀层引入其他杂质元素以及改变晶粒尺寸大小。电化学性能测试后发现,经过活化工艺后的镀层耐蚀性能增大,自腐蚀电位由-0.5481 V升高到-0.3980 V;自腐蚀电流密度由9.941μA/cm~2降低到2.927μA/cm~2。结论钛基体经过活化处理后,生成一层薄的活化膜,这层活化膜通过提高钛基体的表面活性,改变钛基体表面状态,来提高金属电沉积层与钛基体的结合强度,同时镀层的综合性能也得到了改善。     

高速电喷镀制备纳米PTFE镍基复合镀层

研究了以Q235和65Mn钢为基底,经高速电喷镀形成的纳米PTFE镍基复合镀层,考察了喷射速度对镀层沉积速率、表面显微硬度、结晶组织形貌以及镀层结合力的影响,探讨了喷射速度影响镀层性能组织的原因机理。结果表明,喷射速度在4.2～6.3m/s时获得的镀层有较高的沉积速率和表面硬度,晶粒细小、组织致密,镀层结合力较高。     

高速电喷镀制备纳米PTFE镍基复合镀层

研究了以Q235和65Mn钢为基底，经高速电喷镀形成的纳米PTFE镍基复合镀层，考察了喷射速度对镀层沉积速率、表面显微硬度、结晶组织形貌以及镀层结合力的影响，探讨了喷射速度影响镀层性能组织的原因机理。结果表明，喷射速度在4.2-6．3m／s时获得的镀层有较高的沉积速率和表面硬度，晶粒细小、组织致密．镀层结合力较高。     

Effect of bath composition and pulse electrodeposition condition on characteristics and microhardness of cobalt coatings

Nanocrystalline cobalt coatings were produced from cobalt sulfate based electrolytes by using pulse current electrodeposition technique. The effects of bath composition and electrodeposition condition on current efficiency, morphology, structure and hardness of the coatings were investigated and the optimum deposition condition was determined. It was found that increment of cobalt sulfate concentration and sodium dodecyl sulfate (SDS) concentration in the bath had a negligible effect on microhardness of the coatings, while they were effective on electrodeposition current efficiency. Adding saccharin to electrodeposition bath decreased crystallite size of hexagonal close-packed (hcp) cobalt films and increased their microhardness without significant effect on current efficiency. Smoother and less defective coatings were also obtained from baths containing SDS and saccharin. The results revealed that both the current efficiency and microhardness were changed by variation of peak current density and duty cycle. Besides change of smooth morphology of the coatings to needle-shaped one, crystallite sizes and preferred orientation also varied with increasing the current density and duty cycle.     

电沉积方式对 Ni-ZrO2 纳米复合镀层耐腐蚀性能的影响

目的改善Ni-ZrO2纳米复合镀层的耐腐蚀性能。方法分别采用普通电沉积、旋转阴极电沉积、超声电沉积和超声-旋转阴极电沉积四种方式制备Ni-ZrO2纳米复合镀层,分析镀层的ZrO2含量和微观形貌,研究镀层的耐腐蚀性能。结果普通电沉积镀层的ZrO2含量高,但晶粒粗大,组织不够致密,腐蚀速率高,腐蚀后的微观表面存在很多大的腐蚀坑洞。旋转阴极和超声辅助电沉积的镀层ZrO2含量较低,但晶粒有所细化,耐腐蚀性能提高。超声-旋转阴极电沉积的镀层ZrO2含量最低,但晶粒细化程度最高,组织致密度也最好,腐蚀速率低,表面腐蚀特征不明显。结论超声场和旋转阴极都会影响镀层的组织结构和ZrO2含量,超声波和旋转阴极协同作用下的效果最为显著,制备的纳米复合镀层耐腐蚀性能最好。