电沉积Ni-P非晶纳米SiC复合镀层的工艺研究

为了提高非晶镀层的硬度,在Ni-P镀液中加入高硬度、高耐磨性的纳米微粒SiC,采用电沉积方法制备了Ni-P非晶纳米SiC复合镀层.研究了工艺温度、电流密度和镀液中SiC浓度对非晶纳米复合镀层中P含量和SiC纳米颗粒分布的影响,并用扫描电镜对镀层表面进行了观察,通过纳米显微力学探针测量了镀层硬度.结果表明:随电流密度增大和镀液中SiC含量的增加,镀层中纳米SiC的复合量增加;镀液温度在60℃时,镀层中SiC含量最大,复合镀层的硬度显著提高,可达到7.4 GPa,比普通的Ni-P非晶镀层大为提高.     

Mg2B2O5晶须增强AZ91D镁基复合材料表面Ni-P-SiC化学镀层的耐蚀性与SiC含量的关系

有关Ni-P-SiC复合镀层耐蚀性的研究不多.为此,在Mg2B2O5晶须增强AZ91D镁基复合材料表面化学镀Ni-P-SiC层.采用扫描电镜(SEM)、电子探针(EPMA)、电化学方法研究了镀液中纳米SiC含量对镀层表面形貌、成分、耐蚀性、结合力的影响.结果表明:纳米SiC颗粒的加入细化了镀层晶粒,造成了镀层疏松,随着镀液中SiC浓度的增加,复合镀层的耐蚀性逐渐降低,但对基体仍有保护作用,SiC浓度为2g/L时耐蚀性较佳,且镀层与基体结合良好.     

电刷镀纳米Ni-P-SiC复合镀层性能的研究

纳米微粒加入镀液可提高镀层的性能,用电刷镀方法制备了纳米SiC/ Ni-P复合镀层,测试了纳米SiC微粒添加量对复合镀层的硬度、耐磨性的影响,探讨了纳米SiC微粒复合镀层的强化机制及Ni-P晶化过程中的强化作用.结果表明,采用电刷镀制备工艺,能在一定程度上改善纳米微粒在镀液中的分散均匀性并能提高复合镀层性能.在Ni-P合金镀液中适量添加纳米SiC微粒(7～10 g/L),纳米SiC微粒在形成复合镀层时能起到硬质点的强化作用,同时在Ni-P晶化过程中还能在细化晶粒中起到再强化作用.不仅能使镀层硬度提高1.5～1.8倍,还能提高其耐磨性.     

纳米SiC浓度对Ni/纳米MoS_2基复合镀层结构和耐磨性能的影响

采用双脉冲复合电镀技术,在瓦特型镀液中,制备含纳米SiC的Ni/MoS2基复合镀层。研究纳米SiC浓度对复合镀层微观形貌、组织结构、显微硬度和摩擦性能的影响。结果表明:镀液中添加纳米SiC后,Ni/MoS2复合镀层的微观形貌产生明显的变化,随镀液中SiC浓度的增加,复合镀层表面致密度提高;镀液中纳米SiC浓度在1.0~1.5g/L时,组织由Ni+MoS2+SiC组成;纳米SiC为1.5g/L时,显微硬度达到最大,为505HV,摩擦因数为0.28,分别为纯Ni/MoS2的1.6倍和1/2。复合镀层的磨损机制以磨料磨损为主。     

脉冲电沉积Ni-P/纳米Al2O3复合镀层的性能

Ni-P/纳米Al2O3复合镀层具有良好的耐磨、耐腐蚀性能,但有关脉冲电沉积Ni-P/纳米Al2O3复合镀层的报道较少.采用脉冲电沉积方法制备了Ni-P/纳米Al2O3复合镀层,研究了复合镀层的表面形貌、结构及其在5%NaCl溶液中的耐腐蚀性能,并对300,400,500℃热处理后的复合镀层的显微硬度进行了测试.结果表明:Ni-P/纳米Al2O3复合镀层的耐蚀性优于1Cr18Ni9Ti不锈钢,但比Ni-P合金镀层差;随镀液中纳米Al2O3浓度增大,复合镀层的显微硬度提高,镀液中纳米Al2O3浓度为25.0 g/L时制得的复合镀层的硬度为685.5 HV;Ni-P/纳米Al2O3复合镀层经400℃热处理后硬度最高.     

镁合金表面Ni-P-纳米SiC复合化学镀层的耐腐蚀性能

为了提高AZ91D镁合金的应用性能,将纳米SiC引入Ni-P镀液,采用化学镀的方法制备了Ni-P-纳米SiC复合镀层,研究了Ni-P-纳米SiC镀层的孔隙率、盐雾性能以及阳极极化曲线,并与Ni-P化学镀层的耐蚀性进行了对比.结果表明:Ni-P-纳米SiC镀层均匀、致密,纳米SiC在镀层表面呈弥散分布;当纳米SiC浓度为4 g/L时,复合镀层的孔隙率最小,为1个/cm,耐蚀时间(90 h)明显长于Ni-P镀层(60 h),腐蚀电位为-0.58 V,略高于Ni-P镀层(-0.59 V).     

添加PVDF粒子的Ni-P化学复合镀层的耐腐蚀性能

单一镀层难以满足实际要求,复合镀层则可以在较苛刻的条件下服役.在化学镀Ni-P合金镀液中添加聚偏象二乙烯(PVDF)粒子制得了Ni-P/PVDF复合镀层,研究了复合镀层的形貌,并探讨了PVDF的添加量对镀层耐腐蚀性能的影响.结果表明:基拙镀液中加入PVDF粒子后,获得的Ni-P/PVDF复合镀层表面均匀、致密,耐蚀性优于基材和Ni-P合金镀层;随着PVDF添加量的增加,Ni-P/PVDF复合镀层的耐蚀性先增强后减弱,当PVDF的添加量为3.0g/L时,复合镀层的耐蚀性最好.     

电刷镀Ni-P／纳米WC复合镀层工艺及性能研究

为了改善电刷镀Ni-P镀层的硬度和耐磨性,通过在电刷镀Ni-P镀液中加入纳米WC微粒制备Ni-P/纳米WC复合镀层,研究了镀液中纳米WC含量与镀层中纳米WC含量的关系;测定了不同WC含量对镀层硬度和镀层结构的影响.考察了试样在1 mol/L H2SO4,1 moL/L HCl及3%NaCl介质中的耐蚀性.采用扫描电子显微镜(SEM)及X射线衍射(XRD)研究了Ni-P/纳米WC镀层的性能.结果表明,Ni-P/纳米WC电刷镀复合镀层耐蚀性能与原电刷镀Ni-P镀层相当,耐磨性优于电刷镀Ni-P镀层.镀液含25 g/L纳米WC时,电刷镀复合镀层的显微硬度为918 HV.     

α-Al2O3含量对Ni-P复合化学镀层结构及性能的影响

为改善镍磷复合化学镀层的性能,利用X射线荧光光谱、X射线衍射等分析方法研究了α-Al2O3在镀层中的含量对镀层硬度、耐磨性、孔隙率及镀层结构的影响.结果表明:镀液中α-Al2O3加入量小于1 g/L时,随镀液中α-Al2O3浓度的增大,镀层中α-Al2O3的含量提高,镀层硬度与耐磨性增大,孔隙率略有增加;当镀液中α-Al2O3含量为1 g/L时,镀层中α-Al2O3的含量达到最大值4.8%,镀态硬度达到750 HV,约为Ni-P镀层的1.5倍,耐磨性约是Ni-P镀层的5.0倍;镀态镀层为Ni-P非晶与α-Al2O3晶体组成的复合镀层,经400℃热处理1 h后,镀层晶化为Ni3P晶体、Ni基固溶体,表面生成NiO晶体,镀层中α-Al2O3的结构不变.     

Ni-P/Ag纳米复合化学镀层的耐磨损性能

Ni-P/非金属纳米化学镀溶液中纳米粒子容易团聚,镀液难以保持稳定性.在化学镀Ni-P溶液中添加纳米银粒子,在钢铁基体上制备了Ni-P/Ag纳米复合镀层.用显微硬度计、金相显微镜等技术分析了镀层的厚度、硬度和表面形貌,用磨损试验机研究了镀层的耐磨损性能.结果表明:银纳米粒子在镀液中的含量为1.0×10-7mol/,L,银纳米粒子加快了镀层的沉积速度,使纳米复合镀层厚度增加;在相同的施镀条件下,Ni-P/Ag纳米复合镀层比Ni-P镀层具有更高的硬度和更好的耐磨损性能.     

激光熔覆原位自生TiC颗粒增强镍基复合涂层的组织与耐磨性

采用预置粉末法在45钢表面进行激光熔覆镍基Ni60A+x%(SiC+Ti)(质量分数,下同)复合粉末涂层的实验研究。使用往复式磨损试验机对不同涂层材料的熔覆层进行干摩擦磨损实验,利用金相显微镜、扫描电镜(SEM)观察和分析熔覆层的显微组织与磨损形貌。结果表明:复合粉末通过原位反应生成弥散分布的TiC颗粒增强复合涂层,随着(SiC+Ti)含量的增加,颗粒状TiC的尺寸和数目逐渐增加;复合粉(SiC+Ti)含量达到60%时,微观组织有气孔和夹杂缺陷;复合粉(SiC+Ti)含量为48%时,熔覆层耐磨性最佳;复合涂层的磨损主要为磨粒磨损,机理为微观切削和挤压剥落。     

Ni-P-(Ni/SiC)P镀层及其工艺条件的研究

为解决Ni-P-(SiC)P镀层中基体的金属键与增强体的共价键间相容性差,增强体颗粒易脱落,镀层性能降低等问题.采用简单的化学镀方法实现了(SiC)P表面修饰、改性,得到了涂覆型改性(Ni/SiC)P,以(Ni/SiC)P为第二相粒子制备了Ni-P-(Ni/SiC)P化学复合镀层,并初步分析了复合镀机理.实验结果表明:温度、pH值、搅拌速率及(Ni/SiC)P加入量对Ni-P-(Ni/SiC)P镀层的沉积速率及沉积量有较大的影响,本实验条件下的最佳温度为82~86℃;最佳pH值为4.2~4.6;最佳搅拌速率为200 r/mim;最佳粒子加入量10 g/L.SEM、EDS分析显示Ni-P-(Ni/SiC)P镀层均匀、致密,Ni、P、Si沉积量大,耐磨性实验证明Ni-P-(Ni/SiC)P化学复合镀层硬度、耐磨性优于常见的Ni-P、Ni-P-(SiC)P镀层.经表面修饰、改性后得到的(Ni/SiC)P可以进一步提高Ni-P-(SiC)P镀层的使用性能.     

Electrodeposition and mechanical and corrosion resistance properties of Ni-W/SiC nanocomposite coatings

Ni-W/SiC nanocomposite coatings with various contents of SiC nano-particulates were prepared by electrodeposition in Ni-W plating bath containing SiC particulates. The influences of the SiC nano-particulates concentration, current density and stirring rate of the plating bath on the composition of the nanocomposite coatings were investigated. The surface morphologies of the Ni-W alloy and Ni-W/SiC nanocomposite coating were observed using a scanning electron microscope (SEM). The morphology of Ni-W/SiC nanocomposite coating is smoother than that of Ni-W alloy coating. The microhardness of composite coatings increases with the increasing content of the SiC nano-particulates in the coatings. The corrosion behavior of Ni-W alloy and Ni-W/SiC nanocomposite coatings was evaluated by the anodic polarization curves in 0.5 mol/L NaCl solution at room temperature. It shows that Ni-W/SiC nanocomposite coating has better corrosion resistance than the Ni-W alloy coating.     

In-situ TiC Reinforced Composite Coating Produced by Powder Feeding Laser Cladding

A Ni-base alloy composite coating reinforced with TiC particles of various shapes and sizes on medium carbon steel substrate was produced by multilayer laser cladding. The chemical compositions, microstructures and surface morphology of the cladded layer were analyzed using energy dispersive X-ray spectroscopy （EDX）, scanning electron microscope （SEM）, and X-ray diffractometry （XRD）. The experimental results showed that an excellent metallurgical bonding between the coating and the substrate was obtained. The microstructure of the coating was mainly composed of γ-Ni dendrites, a small amount of CrB, Ni3B, M23C6 and dispersed TiC particles. Much more and larger TiC particles formed in the overlapping zone, which led to a slightly higher microhardness of this zone. The maximum microhardness of the coating was about HV0.21200. The effects of the laser processing parameters on the microstructures and properties of coating were also investigated.     

Electrodeposited composite coating of Ni-W-P with nano-sized rod- and spherical-shaped SiC particles

In this research, Ni-W-P-SiC nanocomposite coatings are electrodeposited from the plating solution containing suspension of nano-sized spherical- and rod-shaped SiC particles. The influence of SiC particle charge, applied current density, surfactant addition and the particle shape on the SiC incorporation rate has been studied. The phase structure, microhardness and wear resistance of Ni-W-P-SiC nanocomposite coatings were evaluated using X-ray diffraction (XRD), microhardness tester and wear test apparatus. The surface morphology of the produced coatings and worn surfaces has been investigated using scanning electron microscope (SEM). Additionally, the composite coating exhibited higher hardness and wear resistance than the pure Ni-W-P alloy. Regardless the particle shape, the mechanical characteristics of composite coatings are improved with increasing of SiC wt.% into the matrix. The corrosion behavior of the produced coatings was studied using anodic polarization measurements. The nanocomposite coating incorporating SiC rods exhibited higher mechanical and corrosion performance compared with deposits with spherical SiC nano-particles.     

Characteristics of electrocodeposited Ni-Co-SiC composite coating

Electrodeposited composites are gaining importance for their advantages including low cost, ease and simplicity of operation to tailor made coatings for tribological applications. Generally, composites containing carbides (like SiC) are preferred for high wear resistance along with increased hardness, improved corrosion resistance, and high temperature oxidation resistance as compared to alloy and pure metal electroplating. In the present work, electrolytic codeposition technique was adopted in the deposition of Ni-Co-SiC composite coating on mild steel substrate, using nickel alloyed with cobalt as the binder phase with SiC as dispersed particles. To improve the properties of coating further, Cr plating was also performed. Since the particle size and volume percent variation of dispersoid have great importance in codeposition, so the effect of these two variables on the process of codeposition and properties was observed. Morphological studies of Ni-Co-SiC coating were carried out with scanning electron microscopy and X-ray diffraction analysis to correlate the mechanical and corrosion behaviour of the coating.     

碳化硅增强铝基复合材料界面改善对力学性能的影响

用粉末冶金法制备了致密度较好的镀铜碳化硅增强铝基复合材料,并对碳化硅的表面化学镀工艺进行了分析.通过化学镀前后复合材料力学性能的对比研究表明,碳化硅表面镀铜较好地解决了碳化硅与基体的相容性问题,使复合材料的力学性能得到明显提高.     

聚邻氯苯胺-纳米SiC/环氧树脂复合材料的制备与防腐性能

导电聚合物在金属腐蚀领域存在着潜在的应用前景。为获得防腐性能良好的聚邻氯苯胺(POCl)-nano SiC/环氧树脂复合材料,利用原位聚合法制备了盐酸掺杂态POCl-nano SiC复合改性材料。通过FTIR、UV-vis、XRD、TGA、XPS和SEM等分析手段对其结构、组成和形貌进行了表征。以POCl-nano SiC复合改性材料为填料,环氧树脂为成膜物质,在碳钢表面制备了POCl-nano SiC含量为3wt%、5wt%和8wt%的POCl-nano SiC/环氧树脂复合涂层,并通过SEM对涂层的断面形貌进行了观察。利用Tafel极化曲线和电化学交流阻抗谱研究了涂层在3.5%NaCl溶液中的防腐性能。结果表明,POCl-nano SiC填充量为5wt%的POCl-nano SiC/环氧树脂复合涂层表现出较好的抗腐蚀性能,其腐蚀速率为2.78×10-3 mm/y,腐蚀保护效率高达90.45%。表明适量的POClnano SiC作为环氧树脂涂层的增强相,降低了涂层的孔隙缺陷,在腐蚀介质刺激下,能够在碳钢表面形成钝化保护层。Nano SiC粒子在涂层中充当着类似栅栏结构的屏障,从空间结构上阻止了气体分子和腐蚀溶液向金属基底的渗透。