不锈钢上离子镀硬铬层的性能研究

采用离子镀硬铬技术在不锈钢上制备了不锈钢色硬铬镀层。介绍了其原理和工艺,研究了不锈钢上离子镀硬铬层的表面形貌、硬度、耐蚀性、耐磨性以及结合力。结果表明,不锈钢上离子镀硬铬层表面呈多孔状结构,镀层组成元素为98.02%的Cr及微量(1.13%)的Si。Si元素的掺杂极大地提高了镀层的硬度(可达1 200 HV);硬铬层与不锈钢间的金属扩散层厚度达300 nm,使得硬铬层与不锈钢基体间结合力良好。不锈钢上离子镀硬铬工艺技术环境友好,制备的硬铬层硬度高,具有优良的耐蚀、耐磨性能和强的结合力,是传统镀铬工艺技术的理想替代技术。     

JD电镀黑铬溶液添加剂作用的研究

本文对含有JD-1型添加剂的黑铬电镀溶液的分散能力、深镀能力、阴极极化曲线、镀层的硬度、耐磨性、耐蚀性、光学性能、镀层应力及其与基体材料的结合力作了测定,还研究了镀层的表面形貌。阐明了该添加剂的含量与镀液性能和镀层性能的关系,展示了JD型黑铬电镀工艺在生产上获得应用的原因及广泛的应用前景。     

硬铬电镀技术的发展

从硬铬电镀技术发展史，介绍了新一代ＨＥＥＦ－２５硬铬新工艺。新工艺提供了高质量镀层，硬度高，耐磨性好，耐蚀性能高。为镀硬铬产品提供了最佳工艺。同时又研究了主要技术参数对工艺的影响。     

TC2钛合金表面电镀双层铬工艺

介绍了一种TC2钛合金表面电镀乳白/硬铬双层铬工艺,主要工序有喷砂、除油、活化、氢化、镀乳白铬、真空热扩散退火、喷砂、乳白铬活化和镀硬铬。对乳白铬中间层进行热处理后再电镀硬铬可提高中间层与基体和后续硬铬层之间的结合强度,显著提高钛合金的表面硬度和耐磨性。     

不同类型工件电镀硬铬

硬铬也称耐磨铬.由于铬层硬度高,耐磨性好,成为在磨擦环境下使用的工件表面上常见的镀覆层,电镀硬铬是经常使用的功能性电镀工艺之一.传统的电镀硬铬其最大弱点是阴极电流效率太低,一般只有8%～16%,镀速低,耗能高.     

硬铬在发动机零部件上的应用

1　前言随着世界汽车工业的发展 ,柴油机在车用动力中的应用范围逐渐扩大。现代柴油机更多采用性能良好的铝合金汽缸和薄壁钢质汽缸套。对于这种汽缸、汽缸套的耐磨性能的改善 ,通常采用电镀硬铬工艺。2　硬铬镀层的特性2 .1　硬铬镀层的性能硬铬镀层具有独特的综合性能 ,极高的硬度、优良的结合力和耐蚀性及其耐擦伤和低摩擦系数。2 .1.1　硬度、耐磨性及其相应关系镀铬层具有最高的硬度 ,通常镀铬层维氏硬度可达Ｈｖ75 0～ 10 5 0 ,比铸造铬的硬度更高。这是由于它的组织成分决定的。实验表明 ,随着镀层中氧含量增加 ,镀铬层的硬度也相应…     

不锈钢电镀硬铬的研究

在不锈钢上电镀硬铬,研究了温度与电流密度对镀速、电流效率及磨损失重的影响,确定了各工艺因素对镀层性能的影响程度,得到了具有最佳耐磨性和较高电流效率的电镀硬铬工艺。实验结果表明:当温度为48~50℃,电流密度为25.0A/dm2时,镀层的外观良好、结构致密,镀速为14.8~15.4mg/(cm2·h),电流效率为18.3%~19.0%,镀层具有最高的耐磨性,且与不锈钢基体结合良好。降低温度或增加电流密度,有利于提高耐磨性和电流效率。     

日本表面处理技术近期动向第三部分硬铬电镀取代技术

分别介绍了日本的各种硬铬电镀取代技术——包括三价铬镀铬工艺规范及其镀液分析方法和存在的问题,各种耐磨合金电镀工艺规范、热处理前后镀层硬度以及Ni-W,Fe-W合金电镀工艺配方,复合电镀工艺规范和火焰喷涂涂层性能、喷枪结构等。     

铍青铜零件电镀硬铬

分析了铍青铜材料的特殊性能，在铍青铜零件表面电镀硬铬必须做特殊的活化处理，提供了几种活化处理的溶液组成及操作条件，电镀硬铬工艺操作也与钢铁零件电镀硬铬有所不同，铍青铜零件电镀硬铬后，在200－250摄氏度下除氢处理2－4h，对磷保零件的综合性能十分有利。     

三价铬镀铬工艺对铬镀层耐蚀性的影响

通过极化曲线、交流阻抗图谱和铜加速醋酸盐雾试验,研究了镀液主要组分及工艺条件对三价铬镀液铬镀层耐蚀性的影响,并与六价铬镀液镀层进行了比较。试验结果表明:随主盐含量增加,镀层的耐蚀性有所下降;电镀工艺条件的影响是:pH增大,电镀时间过长,镀层耐蚀性下降。     

W-Ni-Fe合金镀层与硬铬镀层耐磨性的对比试验

国内煤矿机械设备常采用镀铬的方法来提高工件表面的耐磨性,本文在27SiMn钢基体上制备了W-Ni-Fe合金镀层和硬铬镀层,利用显微硬度计、厚度仪等测试了硬铬和镍-铁-钨合金两种镀层的硬度、厚度,并用摩擦磨损试验机测试了两种镀层的耐磨性能并分析了实验结果。实验结果表明:在相同环境和试验条件下,热处理后的W-Ni-Fe合金镀层硬度不亚于硬铬镀层,且在一定载荷范围内,其耐磨性能优于硬铬镀层。     

Polyetheretherketone,hexagonal boron nitride,and tungsten carbide cobalt chromium composite coatings: Mechanical and tribological properties

Composite powder coatings consisting of polyetheretherketone (PEEK), hexagonal boron nitride (hBN), and tungsten carbide cobalt chromium (WC-CoCr) particles were prepared by mechanical grinding and applied on steel substrates by thermal fusion of the thermoplastic polymer. The coatings contained about 20–60 vol% of hBN and WC-CoCr, and were designed to maximize modulus and hardness and minimize friction coefficient and wear rate. The mechanical and tribological properties of single- and double-layered coatings were characterized using nanoindentation and sliding friction and wear measurements. When the hBN concentration was about 30 vol%, the PEEK–hBN composite modulus was lower than that of neat PEEK, which is attributed to the disruption of PEEK crystallization by the filler particles. Upon the inclusion of WC-CoCr particles, the composite's modulus, and hardness showed a substantial increase beyond PEEK values. Elastic moduli of the mixed-filler systems were closer to the Reuss bound than the Voigt bound and could be correlated well with the coating composition using volume-fraction-weighted powers of component properties. Fitted values of the exponent (called the microstructural coefficient) were consistent with the expected continuity and connectivity of the composite's hard and soft phases. Viscoplastic energy dissipation increased with an increase in the polymer-filler interfacial area but decreased with the soft-phase volume fraction. The plasticity index was found to increase logarithmically with the coating modulus. The specific wear rate increased sharply beyond a composition-dependent critical value of the plasticity index. Mechanical polishing of the coating surfaces using abrasive slurries lowered the friction coefficient but increased the wear rate.     

Corrosive wear behavior of HVOF-sprayed micro-nano-structured Cr3C2–NiCr cermet coatings under aqueous media

A novel micro-nano-structured Cr₃C₂–NiCr cermet coating was prepared on 316L stainless steel by high-velocity oxygen fuel spraying technology (HVOF). Cermet coatings with different contents of micro-and nano-sized Cr₃C₂ particles as the hard phase and a NiCr alloy matrix as the bonding phase were prepared and characterized in terms of porosity, microhardness, and corrosive wear resistance in a 3.5% NaCl solution and artificial seawater. Compared to nanostructured coatings, micro-nano-structured coatings avoid decarburization and reduce nanoparticle agglomeration during the spray process, and mechanical and electrochemical properties were improved in comparison with those of conventional coatings. The micro-nano-structured Cr₃C₂–NiCr coating rendered low porosity (≤0.34%) and high microhardness (≥1105.0HV_0.3). The coating comprising 50% nano-sized Cr₃C₂ grains exhibited the best corrosive wear resistance owing to its densest microstructure and highest microhardness. Furthermore, compared to static corrosion, the dynamic corrosion of the coatings led to more severe mechanical wear, because corrosion destroyed the coating surface and ions promoted corrosion to invade coatings through the pores during corrosion wear.     

代硬铬镍基合金镀层的研究进展

为了实现清洁生产,改善生态环境,针对电镀行业中严重污染环境的六价硬铬电镀工艺,广大电镀工作者致力于代硬铬工艺的开发,其中电沉积合金镀层技术将是未来比较理想的代铬工艺.文中综述了近几年来国内外代铬镀层的最新研究进展.重点探讨了几类代铬合金镀层的工艺及耐磨、耐蚀等性能,并指出了目前存在的问题及今后的研究方向.     

高效镀铬工艺镀层性能的研究

了高效镀铬工艺的镀层性能,包括硬度、耐磨性、结合力、耐蚀性、镀层晶体结构和底层微裂纹数目等。实验发现,此种镀层具有较高硬度的原因主要为表面较高的氧化物含量及镀层含有有机碳化物,通过ＸＰＳ分析的方法测定了碳含量与测射深度的关系。     

超音速火焰喷涂316L不锈钢涂层在零件尺寸修复中的应用

为了解决装备核心零部件因磨损、消除腐蚀等带来的尺寸超差问题,制作超音速火焰喷涂316L不锈钢涂层性能试样,对试样涂层的形貌、硬度、耐蚀性开展试验检测研究。结果表明,涂层具有与25Cr3MoA接近的硬度和比30CrMnSiNi2A更好的耐蚀性能。由此,提出采用超音速火焰喷涂316L不锈钢涂层进行零件尺寸修复,制定了可行的修理方案和技术路线,确定了修理工序和参数,形成了相关技术文件,用于指导零件尺寸修复,并在油泵轴和肩轴两类零件上成功应用和装机验证,其性能良好,质量安全。     

Tribochemical behavior of alumina coatings deposited by high-velocity oxy fuel spraying

Alumina is one of the most versatile coatings applied on tools whose working life is reduced due to high wear rate, high temperature, and highly corrosive environments. High-velocity oxy fuel (HVOF) methods are industrially used to deposit this type of coatings. In this study, the effect of the hydrochloric acid concentration on the wear behavior of an HVOF alumina coating was investigated through room-temperature and 60 °C pin-on-disk wear experiments. The results showed that the corrosive environments up to 5% acid did not meaningfully affect the wear damage rate, as compared to the dry condition, due to a contest between friction coefficient and corrosion damage. Nevertheless, the wear rate significantly increased at higher acid concentrations and higher temperatures, since the corrosion effect prevailed over the friction coefficient effect. Also, the predominant wear mechanism was recognized to be adhesive.     

脉冲电沉积工艺参数对Ni-W-P合金镀层性能的影响

针对传统镀硬铬沉积速率低、污染环境等问题,采用脉冲电沉积方法在碳钢表面制备Ni-W-P代铬镀层。采用显微硬度计、扫描电子显微镜、X射线衍射仪和电化学工作站研究了脉冲频率、平均电流密度和占空比对镀层性能的影响。结果表明:随着脉冲频率、平均电流密度和占空比的增加,镀层的硬度和耐蚀性均呈现出先增大后减小的变化规律;当脉冲频率为250Hz,平均电流密度为4.0A/dm2,占空比为30%时,镀层为非晶态结构,表面光滑、平整,结构致密,硬度可达5 140MPa,耐蚀性较好。     

Comparative study on the corrosion and wear behavior of plasma-sprayed vs. high velocity oxygen fuel-sprayed Al8Si20BN ceramic coatings

Corrosion and wear are common problems encountered in the oil and gas industry. These entail the gradual destruction of materials by mechanical action on the opposite surface, and the chemical and/or electrochemical reaction with their environment. In this research, Al8Si20BN ceramic powder with specific properties against corrosion and wear was selected, and it was sprayed with high velocity oxygen fuel (HVOF) and plasma spray methods onto carbon steel substrates. The coatings were characterized with respect to phase composition, microstructure, microhardness and adhesion strength. Their wear behavior was inspected by applying 5, 10, 15 and 20?N loads by pin-on-disc machine, after which the results of both methods were compared. According to the results, the HVOF-coated models were more durable than the plasma-coated models under different loads in the same condition. In addition, the corrosion deterioration of the coated specimens in both brine (3.5% NaCl) and fossil oil were tested for one month (30 days). Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) assessment in 3.5% NaCl solution indicated that the HVOF-sprayed specimens had better corrosion protection than the plasma-sprayed specimens. Generally, the HVOF technique facilitated more durable coats with greater corrosion and tribological resistance compared to the plasma coating technique.     

The effect of spraying temperature on the corrosion and wear behavior of HVOF thermal sprayed WC-Co coatings

Cobalt matrix carbides are favorite cases of wear and corrosion-resistant coatings. Among thermal spray processes the high-velocity oxy-fuel (HVOF) spraying is a popular choice because of its unique properties. In this paper the effect of particles’ temperature on the porosity, corrosion as well as wear behavior of high-velocity oxy-fuel (HVOF) thermally sprayed WC-12Co coating has been studied. The temperature of particles was measured using a Spray-Watch diagnostic system. Also the scanning electron microscopy (SEM), image analysis, and X-ray diffraction (XRD) were used for examining the powder and the coating. The corrosion potential and corrosion current density was evaluated using potentio-dynamic polarization test. Results show that the porosity is affected by thermal flow on the coating surface. Besides, a higher particle temperature resulted in achieving more amorphous phases and eventually the higher corrosion resistance. Sample A was coated with an impact temperature of 2012.4 °C. Although the porosity was higher than other sprayed samples (1.7%), the higher content of amorphous phase led to recording a higher corrosion resistance (64.3E-6A). Sample B was coated with an impact temperature of 1880 °C for which the Jcorr was 67.2E-6 A. Sample C was sprayed with a low impact temperature of 1702 °C for which a surface porosity of 1% and the low corrosion resistance of 79.5E-6A were recorded. Based on the experiments it was concluded that for the WC-12Co coating the corrosion resistant phases have the dominant influences on the corrosion resistance.