Ni-Co-P合金脉冲镀工艺及性能研究

发布时间：2018-03-06 23:19

  本文选题：Ni-Co-P　切入点：脉冲技术　出处：《沈阳理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：镍基合金直流电镀以其镀液稳定、易于控制和制备出的合金镀层性能优良而成为研究的热点,尽管直流电沉积对合金镀层的结晶细化、镀层硬度、耐蚀性的提高有明显的作用,但是通过国内外学者的长期、大量研究后,直流电沉积对镀层的结晶细化、镀层硬度的提高已接近极限。选择新的电沉积制备复合镀层方式成为必然--用脉冲技术取代传统的直流复合电沉积是可预见的有效方式。本文以Ni-Co-P合金镀层为研究对象,采用直流电镀、单脉冲电镀、周期换向脉冲电镀技术制备Ni-Co-P合金镀层。通过极化曲线、电化学阻抗谱测试合金镀层的耐蚀性,采用硬度仪测试合金镀层的硬度,采用SEM图谱分析了各合金镀层的微观形貌,通过EDAX和XRD分析了各合金镀层的元素组成和相组成。研究表明:Ni-Co-P直流合金镀层最佳工艺:硫酸镍:250g/L、氯化镍:40g/L、七水合硫酸钴:25g/L、次亚磷酸钠为:4g/L、硼酸:35g/L、SDS:0.1g/L、电镀密度:5A/dm2、温度:50℃、pH:3.5-4.5、t:30min。合金镀层的性能最好,硬度为629HV(200gf),腐蚀电流为9.56μA,线性极化电阻为4377ohm。Ni-Co-P合金单脉冲镀层最佳工艺:硫酸镍:250g/L,氯化镍:40g/L,七水合硫酸钴:25g/L,次亚磷酸钠:4g/L,硼酸:35g/L,SDS:0.1g/L,温度:50℃,pH:3.5-4.5,t:30min,正占空比为80%,正向平均电流密度为4A/dm2,脉冲频率为1KHz。Ni-Co-P合金单脉冲镀层的硬度为675HV(50gf),腐蚀电流为17.9μA,线性极化电阻为2407ohm。结晶度为69.23%,微粒直径为20.92nm;Ni-Co-P合金周期换向脉冲电镀最佳工艺:硫酸镍:250g/L,氯化镍:40g/L,七水合硫酸钴:25g/L,次亚磷酸钠:4g/L,硼酸:35g/L,SDS:0.1g/L,温度:50℃,pH:3.5-4.5,T:30min,正占空比为80%,正向平均电流密度为4A/dm2,脉冲频率为1KHz,负占空比为8%,负电流密度为0.3A/dm2。Ni-Co-P合金周期换向脉冲镀层硬度为523HV(50gf),腐蚀电流为15.8μA,线性极化电阻为2535ohm,结晶度为91.64%,微粒直径为22.76nm。确定最佳热处理工艺为:热处理温度为300℃、热处理时间为120min。最佳热处理工艺下的Ni-Co-P合金镀层的硬度达到708HV(50gf)、自腐蚀电流为5.10μA,线性极化电阻为3818ohm。晶粒尺寸27.07nm,结晶度为95.53%。最佳的Ni-Co-P合金脉冲镀液中硝酸铈的添加量为0.3g/L,并对最佳硝酸铈添加量的Ni-Co-P合金脉冲镀层测试,硬度达到502HV(50gf),Ni-Co-P合金镀层结晶度最大,为91.74%
[Abstract]:Direct current electroplating of nickel-based alloy has become a hot research area because of its stable bath, easy to control and excellent properties of alloy coating, although DC electrodeposition plays an important role in improving the crystallization, hardness and corrosion resistance of the alloy coating. However, after a long period of research by scholars at home and abroad, the crystallization of the coating was refined by direct current electrodeposition. The hardness of the coating is near the limit. It is inevitable to choose a new electrodeposition method to prepare the composite coating. It is a predictable and effective way to replace the traditional DC composite electrodeposition with pulse technique. In this paper, the Ni-Co-P alloy coating is taken as the research object. The Ni-Co-P alloy coating was prepared by DC electroplating, monopulse electroplating and periodic commutation pulse electroplating. The corrosion resistance of the alloy coating was measured by polarization curve and electrochemical impedance spectroscopy, and the hardness of the alloy coating was measured by hardness tester. The microstructure of the alloy coatings was analyzed by SEM. The element composition and phase composition of each alloy coating were analyzed by EDAX and XRD. The results show that the optimum process of the alloy coating is: nickel sulfate: 250g / L, nickel chloride: 40g / L, cobalt sulfate heptahydrate: 25g / L, sodium hypophosphite: 1 / 4g / L, sodium borate: 35g / L SDSW 0.1 g / L, electroplating density: 5Ar / m2, temperature. The alloy coating has the best properties. Hardness 629HVN 200gfN, corrosion current 9.56 渭 A, linear polarization resistance 4377ohm.Ni-Co-P alloy monopulse coating: nickel sulfate: 250g / L, nickel chloride: 40g / L, heptahydrate cobalt sulfate: 25g / L, sodium hypophosphite: 4g / L, boric acid: 35g / L SDS: 0.1g / L, temperature: 50 鈩，

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