脉冲喷射电沉积纳米晶镍工艺优化研究

采用脉冲喷射电沉积方法在钢基体表面制备了纳米晶镍镀层,研究了占空比、频率、平均电流密度对镀层硬度的影响,并通过正交试验对工艺参数进行优化,用扫描电镜和X-射线衍射仪对镀层表面形貌和晶粒尺寸进行分析。结果表明,制备纳米晶镍镀层的优化工艺参数为:平均电流密度39.8 A/dm2、频率1 000 Hz和占空比20%,此时镀层最致密,硬度最高(530.6 HV),纳米晶镍平均晶粒尺寸最小(13.7 nm)。     

脉冲电流密度对电沉积纳米晶镍织构和硬度的影响

采用脉冲电沉积法制备了韧性较好的纳米晶镍镀层。考察了脉冲峰值电流密度对纳米晶镍镀层织构和硬度的影响。结果表明,随着脉冲峰值电流密度的增加,Ni(111)晶面择优取向程度逐渐增强,晶粒显著减小,镀层的硬度逐渐增加。纳米晶镍镀层硬度与晶粒尺寸的关系符合经典的Hall—Petch效应。     

脉冲电镀镍及其性能的研究

采用瓦特镀镍液,研究了脉冲占空比、平均电流密度、温度对电沉积速率,镀层光亮度和镀层在w=3.5%的NaCl溶液中耐蚀性的影响.用扫描电镜研究了直流和脉冲镍镀层的表面形貌.结果表明:电沉积速率随脉冲占空比、平均电流密度及温度的增大而加快;镀层耐蚀性,光亮度随脉冲占空比增大而变差,随温度、平均电流密度的增大先变好后变差.较佳脉冲电镀条件为:平均电流密度0.75 A/dm~2,脉冲占空比5%,温度45～50 ℃,pH 2.5～3.0.X射线衍射分析结果表明,与直流镀镍相比,脉冲镍镀层在(111)晶面存在择优取向,镀层更致密,性能更好.     

电流密度对Ni-W合金镀层性能的影响

采用脉冲电沉积技术,通过改变电流密度制备出非晶Ni-W合金镀层。利用XRD对镀层的晶粒尺寸和相结构进行表征,利用电化学工作站测试镀层在3.5%的NaCl溶液中的极化曲线和交流阻抗谱。结果表明:镀层的非晶程度随电流密度的增大而增大。当电流密度为15A/dm~2时,镀层的耐蚀性最好,自腐蚀电位和自腐蚀电流密度分别为-288mV和49.4μA/cm~2。     

脉冲频率对Fe-Ni-Cr合金镀层成分及结构的影响

采用脉冲电沉积方法制得纳米晶Fe-Ni-Cr合金镀层,并研究了脉冲频率对镀层成分及结构的影响。结果表明:脉冲频率对Fe-Ni-Cr合金镀层影响很大。当脉冲频率为5 000 Hz时,FeNi-Cr合金镀层的形貌质量最好,厚度为25.41μm,其中Fe的质量分数为63.25%,Cr的质量分数为26.19%,Ni的质量分数为5.89%。脉冲频率为5 000 Hz时制备的Fe-Ni-Cr合金镀层结晶度好,晶粒尺寸为13.44nm,晶面间距为1.887nm。通过脉冲电沉积实现了材料表面纳米化,提高了材料的表面性能。     

正向脉冲占空比对Ni-W-P-CeO2-SiO2纳米复合镀层性能的影响

通过Ni,W、P与CeO2、SiO2纳米颗粒的脉冲共沉积,在普通碳钢表面制备了Ni-W-P-CeO2-SiO2纳米复合镀层.在一定的脉冲频率和平均电流密度下,研究了正向脉冲占空比对纳米复合镀层的化学组成、沉积速率、显微硬度和显微组织的影响.结果表明:增大正向脉冲占空比时,纳米复合镀层的晶粒尺寸增大,沉积速率和显微硬度降低.当正向脉冲占空比控制在10%时,沉积速率最快(为48.6 μm/h),显微硬度最高(为696 HV).纳米复合镀层中的P含量随着正向脉冲占空比的增大而增加,但CeO2、SiO2纳米颗粒及W的含量不断降低,正向脉冲占空比对W的沉积量影响最明显.     

正向脉冲占空比对Ni–W–P–CeO_2–SiO_2纳米复合镀层性能的影响

通过Ni、W、P与CeO2、SiO2纳米颗粒的脉冲共沉积,在普通碳钢表面制备了Ni–W–P–CeO2–SiO2纳米复合镀层。在一定的脉冲频率和平均电流密度下,研究了正向脉冲占空比对纳米复合镀层的化学组成、沉积速率、显微硬度和显微组织的影响。结果表明:增大正向脉冲占空比时,纳米复合镀层的晶粒尺寸增大,沉积速率和显微硬度降低。当正向脉冲占空比控制在10%时,沉积速率最快(为48.6μm/h),显微硬度最高(为696HV)。纳米复合镀层中的P含量随着正向脉冲占空比的增大而增加,但CeO2、SiO2纳米颗粒及W的含量不断降低,正向脉冲占空比对W的沉积量影响最明显。     

光亮纳米晶镍的制备及其耐蚀性研究

通过向瓦特镀镍液中添加自行研发的复合添加剂(由糖精钠、二乙基丙炔胺、丙烷磺酸吡啶鎓盐、乙烯基磺酸钠和羧乙基异硫脲甜菜碱组成),借助直流电沉积法在紫铜表面制得具有不同晶粒尺寸的镍镀层。采用扫描电镜、能谱、X射线衍射、原子力显微镜以及电化学测量技术对镍镀层的表面形貌、元素组成、晶粒尺寸及耐蚀性进行了表征,探讨了晶粒尺寸与光泽度、耐蚀性参数(自腐蚀电流、电荷转移电阻)之间的关系。结果显示,镍镀层表面光亮、均匀、基本无其他杂质元素,晶粒尺寸在纳米级别,镀层光泽度随平均晶粒尺寸的减小而增大,当晶粒尺寸为8 nm时,镀层光泽度达到最大,晶体呈单一的面心立方结构。镀层的耐蚀性随镀层晶粒尺寸的减少而提高,且相比传统添加剂获得的镀层具有更高的耐蚀性。     

平均电流密度对脉冲电镀Ni-Cr-Mo合金镀层的影响

采用脉冲电镀法在Q235钢表面制备Ni-Cr-Mo合金镀层。研究了平均电流密度对镀层的成分、沉积速率、表面形貌和耐蚀性的影响。结果表明:随着平均电流密度的增大,镀层中镍的质量分数先减小后增大,铬的质量分数先增大后减小,钼的质量分数增大;镀层的沉积速率先增大后减小;镀层表面颗粒尺寸增大;镀层的耐蚀性先增强后减弱。当平均电流密度为10A/dm2时,镀层具有最正的自腐蚀电位、最小的自腐蚀电流密度和最大的电荷转移电阻,耐蚀性最好。     

SAS对镍铝水滑石材料超级电容性能的影响

减小电极活性物质晶粒和颗粒尺寸对提高电化学性能具有重要作用.采用共沉淀法通过控制十二烷基磺酸钠(SAS)的添加量合成镍铝水滑石(NiAl-LDHs)电极材料,通过X射线衍射仪、扫描电镜表征电极材料的晶粒尺寸和颗粒尺寸形态,通过电化学工作站测试电化学性能,研究发现:随着SAS添加量增大,镍铝水滑石晶粒尺寸逐渐减小,SAS添加8 mmol时最小,达到2.2 nm;颗粒随着SAS增加更为疏松,尺寸逐渐减小,团聚趋势减小.比电容随着SAS加入量增大逐渐增大.添加SAS 8 mmol的样品在电流密度1 A/g时具有最大比电容953 F/g,在5 A/g电流密度下循环1000圈后比电容仍保持初始值的45.8％,表现出较好的电化学性能.     

双向脉冲电沉积纳米晶光亮镍镀层

采用双向脉冲电沉积法,以糖精和1,4-丁炔二醇作为光亮剂,在钢片上获得了光亮的纳米晶镍镀层.通过正交试验确定最佳的脉冲参教为:正向占空比50%,正向脉冲电流密度30A/dm2,正向周期10ms,反向占空比30%,反向脉冲电流密度8A/dm2.纳米晶光亮镍镀层晶粒细致均匀,孔隙率低,平整性好,无裂纹,具有良好的装饰效果.     

脉冲电镀中脉冲参数对镍镀层显微硬度的影响

采用传统的瓦特镀液通过脉冲电镀制得纯镍镀层。研究了脉冲参数对镀层微观形貌与显微硬度的影 响。结果表明:镀层表面形貌为胞状结构;随着脉冲峰值电流密度的增加,胞状结构的尺寸逐渐变小,镀层显微硬度先增 加后减小;随着占空比的减小,最大显微硬度值对应的峰值电流密度增大,占空比减小到一定值后,峰值电流密度的改变 对显微硬度影响不再明显。     

工艺参数对玻碳材料脉冲电沉积镍晶粒粒径影响的研究

在0.05 cm~2的玻碳材料上利用双脉冲法电沉积纳米晶体镍。在主要成分为300 g/L NiSO_4·6H_2O,45 g/L NiCl_2·6H_2O,40 g/L H_3BO_3,5 g/L C_7H_5NO_3S,0.05 g/L C_(12)H_(25)NaO_4S的镀液中,把晶粒粒径当成研究标准,通过调整脉冲工艺参数,得到最佳工艺条件,即脉冲平均电流密度9 A/dm~2、脉冲占空比r_正=30%、r_反=10%、T_正=100 ms、T_反=10 ms、脉冲频率1 kHz、镀液θ为55℃、pH为1.5。X-射线衍射结果表明,在最佳工艺条件下,利用双脉冲法在玻碳材料上获得了平均粒径在18 nm的纳米晶体镍。     

Influence of cathodic overpotential on grain size in nanocrystalline nickel deposition on rotating cylinder electrodes

Nanocrystalline (nc) nickel was electrodeposited using rotating cylindrical electrodes (RCD) from a Watt’s bath containing saccharin. The effects of cathode rotation speed and saccharin concentration on the cathodic overpotential and grain size were studied. The grain sizes are presented as a function of the cathodic overpotential. All reported cathodic overpotentials were corrected for ohmic overpotentials. X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to determine the deposit grain size. In addition, the influences of cathode rotation speed and current density on the morphology of nanocrystalline nickel were observed by scanning electron microscopy (SEM).     

Comparison of anodic dissolution, surface brightness and surface roughness of nanocrystalline nickel coatings with conventional decorative chromium coatings

The effects of saccharin concentration and pulsating peak current density on corrosion behaviour, surface brightness and surface roughness of nanocrystalline nickel coatings were investigated and the results were compared with those of the conventional decorative chromium coatings. The average grain size of nanocrystalline nickel coatings was determined using X-ray diffraction patterns. Corrosion behaviour was evaluated using electrochemical impedance spectroscopy (EIS) in a 0.6 M sodium chloride solution. A gloss meter and a Suftest device were used to evaluate surface brightness and roughness. Corrosion resistance and brightness of the nanocrystalline nickel coatings increased with increasing the saccharin concentration in the bath. Moreover, brighter nanocrystalline nickel coatings were obtained with increasing the peak current density. In addition, all nanocrystalline nickel coatings were more corrosion resistant than chromium coatings. Those nanocrystalline nickel coatings with average grain sizes of less than 38 nm were brighter and had smoother surfaces than conventional decorative chromium coatings.     

脉冲镀Ni-Co合金镀层内应力及钴含量的研究

研究了脉冲镀Ni-Co合金的工艺,讨论了脉冲电镀中占空比及频率对镀层内应力及钴含量的影响.实验结果表明:镀层内应力随占空比的增加而降低,随脉冲峰值电流密度增加而升高,随温度的升高而降低.镀层中Co的质量分数则随温度的升高而升高.     

电沉积制备镍箔的SEM形貌和抗拉强度

研究了电沉积法制取镍箔的实验条件,并对不同条件下得到的镍箔表面、断面SEM形貌以及抗拉强度进行了分析. 结果表明,动态条件下电沉积镍箔,能够显著提高其极限电流密度,此时SEM形貌显示沿电沉积箔的厚度增长方向,纯镍箔的晶粒逐渐增大. 加入5 g/L糖精能够有效地细化晶粒,并使镍箔表面更加光亮,其抗拉强度也有所提高.     

脉冲电沉积镍-铜合金

采用脉冲电沉积技术在304不锈钢表面制备Ni-Cu合金镀层,镀液组成和工艺条件为:NiSO4ꞏ6H2O 200g/L,CuSO4ꞏ5H2O 10 g/L,十二烷基硫酸钠0.2 g/L,柠檬酸钠80 g/L,糖精0.2 g/L,pH 4.0,温度25°C,搅拌速率30 r/min,平均电流密度40~120 mA/cm2,脉冲频率0~100 Hz,占空比20%~90%,时间30 min。研究了平均电流密度、脉冲频率和占空比对Ni-Cu合金镀层的元素组成、表面形貌和显微硬度的影响,得到较优的工艺参数为:平均电流密度40 mA/cm2,脉冲频率50 Hz,占空比60%。该条件下所得Ni-Cu合金镀层由质量分数分别为56.53%和43.47%的Ni和Cu组成,呈“菜花”状形貌,结晶细致、均匀,显微硬度为614.4 HV。     

Effects of saccharin on the electrodeposition of Ni–Co nanocrystalline coatings

Nickel–Co nanocrystalline coatings were electrodeposited onto a carbon steel substrate with and without saccharin addition. In the absence of saccharin, current density and adsorption of hydrogen complexes and/or intermediate components were distinguished as two effective parameters causing nanocrystalline electrodeposits. In the latter case, the growth active sites can be blocked easily at low current densities. By increasing the current density, a lower degree of adsorption was associated by a significant increase in surface diffusion of adions resulting in grain growth. Although, the nucleation rate is expected to increase with current density, it seems that the Ni–Co grain size is not reduced by the nucleation rate. Adsorption of saccharin molecules and/or decomposed sulfide species occurred in the saccharin contained bath, resulting in slow surface diffusion of adions. Therefore, finer grains were obtained which produced a smooth morphology instead of the pyramidal forms obtained in the absence of saccharin.