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)。     

峰值电流密度对脉冲镀镍钴合金纳米镀层机械性能的影响

研究了峰值电流密度对脉冲镍钴合金纳米镀层的成分、晶粒尺寸、显微硬度、抗拉强度的影响.结果发现:在一定范围内,峰值电流密度的增大,可以降低镀层钴含量、表面粗糙度和晶粒尺寸,使菜花胞状结构更明显,提高镀层显微硬度(最高可达600 kg/mm2)和抗拉强度(最高可达1 200 MPa).然而,峰值电流密度太大又会使显微硬度和强度下降.与采用类似方法制得的纯镍纳米镀层相比,镍钴镀层的显微硬度并未明显升高.这说明在该纳米材料中,固溶强化效果并不很明显,而以细晶强化为主.     

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。     

电沉积纳米镍-钴合金制备金刚石工具

介绍了采用纳米镍-钴镀层作为新型胎体材料,制备电镀金刚石工具的方法及其特点.纳米镀层是在瓦特型槽液中通过方波电流而得到的,脉冲参数为电流导通时间1 ms,电流关断时间15 ms,峰值电流密度100 A/dm2.镀层中钴的质量分数量为8.5%,表面较光整,晶粒尺寸在15 nm左右,显微硬度达到6 000 MPa,与纯镍纳米镀层的相近,但抗拉强度明显高于纯镍纳米镀层的.由其制得的工具平均寿命比纯镍纳米胎体材料工具高15.5%.     

激光重熔纳米晶镍镀层的研究

介绍了喷射电镀的基本原理,采用自行设计制造的喷射电镀设备制备纳米晶镍镀层,并对镀层进行激光重熔处理.重点研究了在直流电源和脉冲电源作用下,电流密度对镀层金属的微观结构的影响,以及采用激光重熔处理对直流纳米晶镍镀层形貌的影响;考察了金属基体、喷射电镀层以及激光重熔后的镀层的显微硬度的变化.研究结果表明:与基体金属相比,喷射电镀层的显微硬度有明显提高;经过激光重熔处理后镀层的显微硬度得到进一步提高.     

氨基磺酸盐镀镍的微观织构与硬度

采用氨基磺酸盐镀液电沉积镍层,通过WLI,SEM,XRD和MHT对镀层的三维形貌、微观织构及硬度进行分析。结果表明:在镀液中不含添加剂的情况下,随着阴极电流密度的增加,镀层晶粒细化,但镀层致密性变差且硬度呈近似线性关系降低;镀液中加入适量添加剂后,镀层衍射谱特征和各晶面的择优取向度无明显改变,但在相同阴极电流密度下所得镀层的晶粒更加细小且硬度有所提高。     

峰值电流密度对脉冲电沉积Ni-Co-CNTs复合镀层机械性能的影响

研究了峰值电流密度对脉冲电沉积Ni-Co-CNTs复合镀层机械性能的影响。结果表明:当峰值电流密度升高时,镀层表面变得粗糙;随着峰值电流密度的增加,镀层中碳的质量分数先增加后下降,当峰值电流密度为80 A/dm~2时,镀层中碳的质量分数达到最大值;镀层的显微硬度和抗拉强度均在峰值电流密度为100 A/dm~2附近时达到其最大值,且高于直流电沉积时所得镀层的显微硬度值和抗拉强度值。说明采用脉冲电沉积工艺可以提高镀层的机械性能。     

脉冲喷射电沉积镍工艺的研究

由于直流电沉积镍使用极限电流密度下,沉积速度低。本文介绍脉冲喷射电沉积的方法制备镍镀层。研究了脉冲频率、占空比、电流密度及糖精对镀层晶粒尺寸的影响。结果表明：镀层晶粒尺寸随脉冲频率、平均电流密度的增大而减小;随空比的增大而增大。少量糖精的加入能有效降低镀层晶粒尺寸。     

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.     

电沉积法制备纳米晶Ni-Co合金镀层

在氨基磺酸盐镀液体系中,采用电沉积法制备了纳米晶镍镀层和四种纳米晶Ni-Co合金镀层,采用FESEM、EDS和XRD表征了镀层的表面形貌、成分和晶体结构。结果表明,镍镀层和四种Ni-Co镀层的晶体结构都是简单面心立方结构;与镍镀层相比,Ni-Co合金镀层的平均晶粒尺寸减小,且当镀层钴含量为41.3%时,Ni-Co合金的平均晶粒尺寸最小为14.6 nm。在一定范围内,钴含量的增加有利于改善Ni-Co合金镀层的表面质量以及实现晶粒细化。     

Hardening effect induced by incorporation of SiC particles in nickel electrodeposits

Pure Ni and nickel matrix composite electrocoatings containing micron- and nano-SiC particles (1 μm and 20 nm respectively) were produced under direct and pulse current conditions from an additive-free Watts type bath. The effect of the particle size, codeposition percentage of SiC and type of imposed current on the microhardness as well as on the microstructure of the electrodeposits were investigated. Ni/SiC composite deposits prepared under either direct or pulse current conditions exhibited a considerable strengthening effect with respect to pure Ni coatings. The improved hardness of composite coatings was associated to specific structural modifications of Ni crystallites provoked by the adsorption of H⁺ on the surface of SiC particles, thus leading to a (211) texture mode of Ni crystal growth. Pulse electrodeposition significantly improved the hardness of the Ni/SiC composite coatings, especially at low duty cycles, in which grain refinement and higher SiC incorporation (vol. %) was achieved. The enhanced hardness of Ni/nano-SiC deposits, as compared to Ni/micron-SiC composites, was attributed to the increasing values of the number density of embedded SiC particles in the nickel matrix with decreasing particle size. In addition, the observed hardening effects of the SiC particles might be associated to the different embedding mechanisms of the particles, which could be characterized as inter-crystalline for micron-SiC and partially intra-crystalline for nano-SiC particles.     

Influence of pulse plating parameters on the synthesis and preferred orientation of nanocrystalline zinc from zinc sulfate electrolytes

The influence of pulse electrodeposition parameters (current on-time T_on, current off-time T_off, and pulse current density J_p) was investigated on the surface morphology and grain size of zinc electrodeposited from a sulfate bath containing polyacrylamide and thiourea additives. The grain size and surface morphology of zinc deposits were studied by field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM), and the preferred orientation of the deposits was studied by X-ray diffraction. At constant current off-time and pulse current density, the grain size decreased asymptotically with increasing current on-time. In contrast, increase in the current off-time at constant current on-time and pulse current density resulted in grain growth. A progressive decrease of the grain size was observed with increasing pulse current density at constant current on-time and off-time. Nanocrystalline zinc with an average grain size of 38 nm was obtained at a pulse current density of 1200 mA/cm². The crystallographic orientations developed were correlated with the change in the cathodic overpotential, the angle between the preferred oriented plane and the lowest energy of formation plane (0 0 0 2), and the pulse electrodeposition parameters.     

脉冲频率对Ni-WC纳米复合镀层耐蚀性及硬度的影响

采用脉冲电沉积法在304不锈钢基体上制备出Ni-WC纳米复合镀层,并研究了脉冲频率对Ni-WC纳米复合镀层的耐蚀性及硬度的影响。结果表明:随着脉冲频率的增大,Ni-WC纳米复合镀层的平均晶粒尺寸先减小后增大,硬度先增大后减小。当脉冲频率为1 000Hz时,制备的NiWC纳米复合镀层耐蚀性最佳,具有最正的自腐蚀电位和最小的自腐蚀电流密度。     

脉冲电流密度对Ni-WC纳米复合镀层耐蚀性及硬度的影响

采用脉冲电沉积法在304不锈钢基体上制备出Ni-WC纳米复合镀层,并研究了脉冲电流密度对Ni-WC纳米复合镀层耐蚀性及硬度的影响。结果表明:随着脉冲电流密度的增大,Ni-WC纳米复合镀层的织构呈现规律性变化,晶粒尺寸先减小后增大,硬度先增大后减小。当脉冲电流密度为10A/dm2时,Ni-WC纳米复合镀层的耐蚀性最好,硬度最高。     

Pulse plating of Zn-Ni alloy coatings

In this work the electrodeposition of Zn-Ni alloy coatings from a chloride-based electrolyte using a square-wave current pulse-plating technique was investigated. The effects of the pulse plating variables (peak current density, on-time and off-time) and some important bath conditions (ZnC1₂ and NiCl₂.6H₂O concentrations in the bath as well as bath temperature) on the chemical composition, surface morphology, grain size, phase distribution and preferred orientation of the deposits were studied. The bath temperature had a very strong effect on the composition of the deposits which, in turn, had very strong effects on the phases present, surface morphology and grain size. The peak current density was found to have little effect on the composition and phases present, but had considerable effect on grain size. The on-time and off-time had no significant influence on the characteristics of the deposits, except for slight grain refinement observed with increasing off-time. Only the , and crystal phases were found in the deposits while other intermediate phases such as and were not found in any of the deposits produced in this work. Grain refinement of the deposits down to the nanocrystalline range can be achieved by increasing the Ni content of the deposits.     

任意可调Zn-Co合金镀层的电沉积

The effects of pulse parameters on the cobalt content, surface morphologies and grain size of Zn-Co alloy deposits were studied using a pulse plating technique with a square-wave current containing reverse pulse. Average current density and reverse anodic current density amongst the variables investigated have very strong effects on the cobalt content in the Zn-Co alloy deposits. Grain size, surface appearance and internal stress in the deposit were improved significantly by introducing the reverse current. Varieties of Zn-Co alloy compositionally modulated multilayer (CMM) coatings with large differences in cobalt contents for different sublayers were electrodeposited by designing corresponding waveforms using a computer-aided pulse plater and characterized in terms of surface morphologies. Cross-sectional morphologies of the Zn-Co alloy CMM coatings, examined using field emission gun scanning electron microscopy (FEGSEM), confirmed the layered structure.     

离心高速电镀镍工艺研究

为提高电镀镍的沉积速率以提高劳动生产率 ,采用自行研制的离心高速电镀镍装置。研究了电流密度与沉积速率、晶粒尺寸及镀层硬度的关系 ,结果表明 :采用此装置 ,镀液在阴极表面切向流速、极限电流密度及沉积速率均增大 ,使得镀层晶粒更细致 ,硬度更高。