脉冲参数对等离子电沉积镍镀层结构和性能的影响

采用高频脉冲电源在纯铜基材上以等离子电沉积技术制备出了金属镍镀层,研究了高频脉冲频率以及占空比变化对等离子镀镍层结构和性能的影响。对镀层进行了SEM,显微硬度以及划痕结合力的表征。结果表明,随着高频脉冲频率和占空比的增加,镀层表面的熔融态形貌逐渐减少,镀层逐渐变得致密,表面硬度与结合力值也相应提高。通过讨论脉冲电源的能量作用方式,分析了频率及占空比对等离子电沉积镍层表面结构及性能的影响规律。     

全氢聚硅氮烷用于塑料表面硬化涂层的研究进展

塑料制品应用面广阔,但高分子聚合物自身结构的特点导致塑料制品表面在外力作用下易产生划痕,这既影响了美观,又降低了材料的性能和使用寿命。目前对其进行硬化处理得到了广泛的开发和使用,其中,表面涂覆硬化涂层是解决这一问题较为方便的方法。主要介绍了基于全氢聚硅氮烷制备塑料表面硬化涂层的国内外研究进展,并对不同的塑料基材已取得的研究结果进行了分类。全氢聚硅氮烷应用于PS表面,通过PHPS改性PS衍生物,在保证两种聚合物相容性良好的前提下,获得了高硬度的有机无机杂化涂层;应用于PC表面,通过控制PHPS/PMMA接枝聚合物结构,获得了透明、附着力优异、硬度高的有机无机杂化涂层,PHPS/有机硅氮烷转化后的涂层也极大地提高了PC表面的硬度;应用于PET和PMMA表面,将PHPS直接涂覆在基材表面即可获得致密、透明、附着力优异的高硬度涂层;应用于其他塑料表面,还可以提高基材的水蒸气阻隔性能、热稳定性等。最后指出随着涂层材料应用领域的不断扩大及对防护性能要求的不断提高,PHPS转化涂层未来在塑料基材表面增硬方面发展潜力巨大,应用前景广阔。     

Mg合金的腐蚀与防护

介绍了Mg合金的腐蚀原理、腐蚀类型以及合金元素在镁合金中的作用。综述了Mg合金的化学转化膜、阳极氧化、微弧氧化、化学镀等经典的表面处理方法 ,以及快速凝固工艺和表面改性技术对Mg合金表面耐蚀性能的影响。Mg合金易发生全面腐蚀、电偶腐蚀、点蚀、应力腐蚀和高温氧化。解决Mg合金腐蚀的方法有 :一是研究新合金 ,提高Mg合金自身的热力学稳定性 ,稀土Mg合金是最有前途的耐蚀合金 ;二是通过表面处理使Mg合金表面富SiO2 和Al2 O3 、含SiC和F-等物质或获得的非晶态的涂层结构能有效地提高Mg合金的耐蚀耐磨性能 ;三是改进加工工艺 ,快速凝固和激光退火不仅能获得力学性能优秀的Mg合金产品 ,还能获得纳米结构的表面涂层防护膜 ,提高Mg合金的耐蚀耐磨性能。使镁合金表面涂层结构纳米化、玻璃化是表面处理工艺的发展趋势。     

镁合金微弧氧化过程中电源模式对颗粒掺杂的影响

目的采用含颗粒电解液是目前最常用制备具有更佳性能微弧氧化膜层的方法之一,主要研究微弧氧化过程中颗粒掺杂与电源模式的关系。方法在Y2O3颗粒质量浓度为0~10 g/L的电解液中,分别以单极脉冲和双极脉冲电源模式制备一系列微弧氧化膜层,并从表面形貌、表面元素组成、截面形貌及耐蚀性能等方面对膜层进行综合评价。结果分散在电解液中的颗粒带有负电荷,在微弧氧化过程中发生电泳现象。在单极脉冲电源模式下,颗粒受正电吸引而发生定向迁移,在试样附近聚集并且吸附至表面,从而参与下一步的微弧氧化膜层形成过程。随着电解液中颗粒浓度的提高,分散在微弧氧化膜层表面的Y2O3颗粒数量增多,膜层表面的Y元素含量增加,膜层变得致密,耐蚀性能因而提高。在双极脉冲电源作用下,由于电场的交替变化,颗粒难以聚集在试样周围,颗粒的掺杂只能通过随机熔融包覆进行,因而参与到微弧氧化过程中的颗粒数量较少。结论颗粒掺杂受电场力影响,在单极脉冲模式下,颗粒的掺杂浓度对膜层的性能影响明显;在双极脉冲电源模式下,负向电流的引入不利于颗粒掺杂至氧化膜层,颗粒的掺杂浓度对膜层的性能影响不明显。     

Observations on the uniformity of immersion tin coatings on copper

The development of chemical tin coatings by a replacement reaction Cu+Sn²⁺Cu²⁺+Sn from hydrochloric acid based and methanesulphonic acid based baths on the inner surface of a copper tube was studied by transmission electron microscopy and scanning electron microscopy in order to explore the factors influencing the uniformity of tin coatings. Despite the fact that tin coatings develop in different ways in studied baths, uniform coatings are equally plated from both these baths when the substrate surface is clean and smooth. However, differences in the surface-sensitivity, i.e. the dependence of coating uniformity on the substrate surface condition, of plating baths materialise when plated on irregular or improperly cleaned substrate. A hydrochloric acid based bath may yield non-uniform coatings on irregular or improperly cleaned substrate, since large-sized grains develop immediately after coating initiation. These large grains are suggested to orientate to follow the contours of impurity particles or surface irregularities introducing misalignment in grain columns and, thus, non-uniformity into coatings. In contrast, a methanesulphonic acid based bath is still able to produce uniform tin coatings on contaminated or rough surfaces, as the coating is proposed to accommodate to substrate surface irregularities by the build-up of a nanocrystalline zone at the early stages of tin coating deposition. Sulfur-containing elements in this methanesulphonic acid based plating bath play the central role in the nanocrystalline layer formation.     

脉冲偏压占空比对电弧离子镀TiAlN涂层的影响

通过优化电弧离子镀工艺参数改善TiAlN涂层结构及性能对TiAlN涂层应用具有重要的实用价值。本文利用脉冲偏压电弧离子镀制备了TiAlN涂层,研究了偏压占空比对TiAlN涂层结构及性能的影响,结果发现：随着占空比增加,涂层表面缺陷密度和表面粗糙度先降低后增大,占空比为70%时,制备的涂层表面缺陷密度和表面粗糙度最低。随着占空比增加,涂层的硬度和耐磨性得到明显改善,但占空比超过50%后继续增加占空比反而降低了涂层的硬度和耐磨性。TiAlN涂层与Si3N4球对磨时的主要磨损机制为黏着磨损和氧化磨损。     

AZ31镁合金表面含纳米SiC氟化镁膜层的制备及耐腐蚀性能

为了提高 MgF2 膜层的耐腐蚀性能,利用微弧氧化工艺,通过在 NH4F-EG 电解液中添加纳米 SiC 颗粒,在 AZ31 镁合金表面制备含 SiC 的 MgF2 -SiC 膜层,并探究纳米 SiC 颗粒的浓度对 MgF2 膜层组成、结构和耐腐蚀性能的影响。 采用 SEM、EDS、XRD、XPS 等测试方法对含 SiC 的 MgF2 膜层的微观组织、元素含量和物相组成进行分析,利用电化学工作站对膜层的耐腐蚀性能进行测试。 结果表明:电解液中的纳米 SiC 颗粒成功进入 MgF2 膜层中。 随着电解液中纳米 SiC 浓度的增加,膜层中的 Si、C 元素含量增加,Mg、F 元素含量减少,膜层变得致密平整,孔隙率减少,膜层缺陷得到有效改善,膜层厚度减小;MgF2 膜层的耐腐蚀性能先增大后减小,当电解液中纳米 SiC 的浓度为 5 g / L 时,膜层的耐腐蚀性能最优。 因此,在 NH4F-EG 电解液中添加纳米 SiC 颗粒,可以在 AZ31 镁合金表面制备出含 SiC 的 MgF2 -SiC 膜层, 且耐腐蚀性能优于不含 SiC 的 MgF2 膜层。     

电流密度和施镀温度对铝合金表面Ni-SiC-MoS2复合镀层显微组织的影响

目的研究电镀工艺参数中的电流密度和施镀温度对铝合金表面Ni-Si C-MoS_2复合镀层组织形貌及成分的影响。方法利用复合电镀的方法在铝合金上制备Ni-Si C-MoS_2复合镀层。通过扫描电子显微镜、能谱仪以及显微硬度仪,分析不同电流密度和施镀温度下复合镀层的组织结构、成分、界面之间的结合情况以及显微硬度。结果电流密度为4 A/dm2时,镀层与基体的结合差,镀层表面粗糙不平;当电流密度增加到5 A/dm2时,镀层与基体结合紧密,并且镀层表面平整;当电流密度增大到6 A/dm2时,镀层表面平整度变差。施镀温度为40℃时,镀层厚度较薄;施镀温度为50℃时,镀层与基体结合良好,镀层表面平整;当施镀温度上升到60℃时,镀层与基体结合处出现裂纹,镀层质量下降。随电流密度和施镀温度的升高,镀层中Si C和MoS_2摩尔分数先增加后减小,显微硬度先增大后减小。结论采用复合电镀的方法在铝合金表面可以制备出Ni-Si C-MoS_2复合镀层,当电流密度为5 A/dm2、施镀温度为50℃时,制备出的Ni-Si C-MoS_2复合镀层表面平整,厚度均匀,Si C与MoS_2摩尔分数可分别达到10.40%和0.77%。复合镀层的显微硬度与其Si C含量成正比,最高可达357.7HV0.01,是基体合金硬度的3.7倍。     

Novel processing in inert atmosphere and in air to manufacture high‐activity slurry aluminide coatings modified by Pt and Pt/Ir

Slurry‐derived coatings are an interesting alternative method to pack aluminization of nickel‐base superalloys, which provide similar properties and protection at high temperatures. For highest performance, these aluminide coatings are modified by the addition of Pt or, as recent research suggests, with Pt/Ir. While the combination of Pt and Pt/Ir with an out‐of‐pack process is state of the art, slurry coatings are of special interest as a repair method for turbine blades. In this study, the microstructural evolution of slurry‐derived coatings manufactured on CM 247 in inert atmosphere as well as in air was investigated. Layers of Ni, Pt, and Pt/Ir mixtures were electrodeposited. After annealing, a diffusion heat‐treatment with a slurry containing aluminum or aluminum–silicon powder was applied on the samples. The addition of silicon is well known to be beneficial for hot corrosion environments. The reaction and interdiffusion behavior of aluminum/aluminum–silicon determines the microstructural evolution of the coatings. Depending on the initial electroplated layer on the surface, different microstructures can be obtained, such as the Pt/Ir‐modified beta phase (Ni,Pt)Al or two‐phase layers of PtAl₂ and NiAl. Additionally, the reactivity between the elements at the surface and those from the slurry was shown to determine homogeneity and surface roughness of the diffusion coating, also depending on the atmosphere used during slurry aluminization. Finally, it was demonstrated that iridium has a high influence on the diffusion behavior and especially the distribution of platinum in the coatings. Such new coatings have the potential to overcome some disadvantages of conventionally manufactured high‐activity aluminide coatings, as the combination of Pt/Ir‐electroplating with the slurry process results in less detrimental substrate elements like molybdenum or tungsten close to the surface.     

汽车表面达克罗防腐涂层的组织和性能

介绍了达克罗技术在汽车工业中的应用情况，对达克罗防腐涂层表面组织形貌和耐腐蚀性能进行了研究，并和镀锌、镀铝涂层的耐腐蚀性能进行对比。结果表明，锌、铝、铬等元素在达克罗涂层中分布均匀，片状的锌粉和铝粉层叠，而无定形的铬酸盐聚合物分布在锌、铝之间。涂层覆盖在被保护工件表面，形成牢固的防腐蚀保护涂层。     

绿色海洋防污材料的表面构筑研究进展

海洋生物污损已成为影响船只与装备在海洋环境中服役性能的全球性问题。因此,发展高效、广谱、环境友好的防污材料势在必行。借鉴海洋生物表皮具有的天然防污特性,人们通过对材料的表界面组分、形貌设计,获得了一系列环境友好型防污材料。文中系统归纳和评述了低表面能材料、表面亲水性材料、表面织构化材料和表面植绒材料等依靠表面物化性能调控来获得具有优异防污表现的绿色防污材料的研究进展,最后指出当前绿色防污材料存在的问题及未来的发展方向。     

液氮辅助冷却激光熔覆Al基非晶涂层的组织与耐蚀性

采用激光熔覆加液氮辅助冷却技术在S355海洋钢表面制备Al基非晶涂层,运用SEM、XRD、电化学工作站等技术分析了涂层腐蚀前后表界面形貌及物相组成,研究了液氮辅助冷却对涂层性能的影响以及涂层在5%NaCl溶液中浸泡10、20、40和80 d后的腐蚀性能。结果表明:经过液氮辅助冷却后涂层中存在少量的非晶AlFeNi相;涂层与基体形成了良好的冶金结合;表面组织细小,增强相TiC均匀弥散分布,且裂纹气孔较少。涂层表面显微硬度增加15%;残余应力与自然冷却时基本持平,均为拉应力;其耐蚀性也得到了显著提升。     

石油储罐几种外防护涂层性能的评价

涂层保护是石油储罐腐蚀防护的主要措施。为此,国内曾先后开发了醇酸银粉漆、氯磺化聚乙烯涂料、高氯化聚乙烯涂料、丙烯酸聚氨酯防腐蚀涂料、常温固化型氟碳涂料等,并在不同时期的工程建设中得到应用。不同的涂料具有不同的表面性能,设计部门和使用单位往往根据涂料性能和实际需求选择涂料。醇酸银粉漆和氯磺化聚乙烯涂料因其使用寿命短而被淘汰。对高氯化聚乙烯涂层、丙烯酸聚氨酯涂层、常温固化型氟碳涂层进行了光老化、盐雾、酸碱浸泡、表面能、耐沾污性等多种表面性能的测试评价。结果表明:常温固化型氟碳涂层综合性能优于高氯化聚乙烯涂层和丙烯酸聚氨酯涂层。     

Effect of surface condition on the oxidation behaviour of MCrAlY coatings

Coatings of the MCrAlY type (M = Ni, Co) are commonly used as overlay coatings and as bond coats (BC's) for ceramic thermal barrier coatings (TBC's) in industrial gas turbines. During high temperature service the MCrAlY coatings form aluminium based surface oxide scales. The technologically most relevant properties of the oxide scales, growth rate and adherence do not only depend on the exact MCrAlY composition but also on the surface condition after coating manufacturing. Depending on the coating manufacturing process, the MCrAlY surfaces may substantially differ in roughness. In addition the coatings may be subjected to surface treatments (e.g. shot peening, grinding or smoothening prior to deposition of TBC). In the present work the effect of the surface roughness commonly prevailing in the case of vacuum plasma sprayed MCrAlY coatings on the morphology and composition of the alumina scales formed during high-temperature oxidation was studied. For this purpose free standing coatings with rough and polished surfaces were oxidised in the temperature range from 800 to 1100 °C with exposure times up to 1000 h. The surface scale composition and morphology were analysed by optical metallography and SEM. Fluorescence spectroscopy was used for stress measurements in the oxide scales. It has been found that the oxide scales formed on rough surfaces of MCrAlY coatings have an intrinsically different morphology and growth rate compared to those formed on the flat ground surfaces.     

双镀层对A3钢在硫酸溶液中腐蚀速率的影响

尝试在A3钢表面施镀镍 铅双镀层,以提高其在硫酸溶液中的耐蚀性能.利用腐蚀失重方法分别测定了镀铅层与镀镍 铅双镀层的A3钢在硫酸中的腐蚀速率,并借助扫描电镜对双镀层的形态进行了观察与分析.试验表明:施镀镍 铅双镀层能明显提高A3钢的耐蚀性能.认为:镍层遮盖了A3钢表面,使阳极电位提高,腐蚀驱动力减小;铅在硫酸中析氢超电压大,且容易生成致密的硫酸铅膜,这些因素是材料耐蚀性得到明显提高的重要原因.     

Obtaining composite oxidic coatings on the surface of aluminum and alloys thereof

We have obtained and investigated manganese-containing oxide-ceramic coatings on the surface of D16 aluminum alloy. It is shown that such coatings are promising as electrode materials in electrolytic systems and when the protective properties of the substrate are enhanced.     

Wear and erosion behavior of plasma-sprayed WC-Co coatings

Wear mechanisms of air plasma-sprayed WC-12%Co coatings were studied by using a dry sand rubber wheel (DSRW) abrasive, ring-on-square adhesive wear, and alumina particle erosion tests. Coating properties such as intersplat cohesive strength, porosity, surface roughness, hardness, and retained carbide as well as microstructures were characterized to assess their relationship on wear performance. Porosity, hardness, surface roughness, and retained carbide of the coatings are not the principal factors affecting wear performance. Intersplat cohesive strength of coatings, measured by a simple bonding test, is the most significant factor that relates to the wear rate of thermal spray coatings.     

KF-KCl熔体中电沉积TiB2镀层

在铝工业中TiB2是一种非常有前途的阴极内衬取代材料.本研究首先通过热力学分析验证了在Ti-B-C体系生成TiB2的可能性,然后在K2TiF6和KBF4作为活性物质的KF-KCl熔体中以石墨为基体通过直流电沉积(CCP)和周期断开电流电沉积(PIC)技术制备了TiB2镀层,并且研究了电流密度和电镀技术对镀层表面平整度、致密度和晶粒尺寸的影响.结果表明,当电流密度为0.8 A/cm2时,能够得到厚度均匀且和基体具有良好附着的TiB2镀层;和CCP相比,采用PIC技术制备的TiB2镀层表面平整度和致密度都得到明显改善,并且晶粒也更为细小.XRD分析表明镀层由相对纯净的TiB2组成,并且镀层择优取向均为(001)面,这和二维晶核理论的预测相吻合.     

热喷涂Ni基复合涂层重熔处理的研究现状

热喷涂Ni基复合涂层因具有耐磨、耐腐蚀及耐高温等特点,被广泛应用于机械零件的表面修复和保护。但是,热喷涂层为典型的层状结构,具有微缺陷含量较高、与基体结合强度低等特点,难以适应苛刻的工作环境,其应用和发展受限。重熔处理可以消除热喷涂层的层状结构,消除或部分消除孔隙、裂纹等微缺陷,使涂层与基体形成冶金结合,提高涂层的使用性能。本文首先介绍了几种适用Ni基复合涂层的重熔技术(即激光重熔、火焰重熔、感应重熔等),随后介绍了重熔处理对Ni基复合涂层表面完整性(即微缺陷、结合强度和硬度)的影响,接着分析了重熔处理对Ni基复合涂层两种服役性能(即耐磨性、耐腐蚀性能)的影响,最后总结了目前在关于Ni基复合涂层重熔技术研究中存在的问题,进而探讨了相应的解决方案,并指出挖掘新的表面重熔技术和对不同的材料体系进行针对性研究是未来重点发展的方向。     

Influence of post-treatment on the corrosion resistance of PEO coated AM50B and AM60B Mg alloys

Magnesium alloys are highly reactive and require protection for their successful applications. In this work, coatings of 10 μm and 25 μm nominal thicknesses were prepared by Plasma Electrolytic Oxidation on AM50B and AM60B alloys. The effect of subsequent post-PEO treatments such as alkaline phosphate, alkaline silicate and sol-gel sealing was studied on coatings with 10 μm thickness. The microstructure and composition of the PEO coatings and post-treated coatings were analysed by Scanning Electron Microscope and Energy Dispersive X-ray Spectroscopy. Phase analysis of the coatings was carried out using X-ray Diffraction method. Potentiodynamic polarization method was used to evaluate the corrosion behaviour of these coatings in 3.5% NaCl solution. Electrochemical corrosion results indicated that the sealed PEO coatings of 10 μm thickness showed better corrosion resistance than the unsealed PEO coatings of 25 μm thickness. The structural surface defects of the PEO coatings were sealed by post-treatments resulting in decreases in surface roughness and open pores. Sol-gel post-treatment provided the most effective sealing to the PEO coatings.