Protective Coatings on Heat-Resistant Nickel Alloys (Review)

The literature on materials for protective coatings on heat-resistant nickel alloys and methods for their production is reviewed in order to generalize the results and determine the principal directions for solution of the problem under consideration. It is shown that a promising approach is the development of layered composite ceramic coatings which, thanks to a graded variation of properties, are able to provide an optimal combination of adherence, mechanical strength, and corrosion and heat resistance. The methods of physical vapor deposition, plasma spraying, and electron-beam deposition remain the principal industrial processes for coating deposition.     

Industrial Electron-Beam Equipment for Deposition of Protective Coatings: Overview

Powder Metallurgy and Metal Ceramics - The current development of industrial electron-beam equipment for the deposition of protective coatings on gas turbine blades by high-speed electron-beam...     

新一代连续带钢真空镀膜技术的发展现状与展望

介绍了新一代连续带钢镀膜技术--真空镀膜的工艺特点及应用现状.热蒸发喷射、磁控溅射、电子束蒸发和等离子增强型电子束蒸发是目前最接近工业化的连续带钢真空镀膜工艺, 并在多家钢铁公司的真空镀膜中试线上得到了应用.其工艺特点是环保、良好的薄膜综合性能和可沉积材料的多样性及工艺组合的多样性,其镀层系统主要包括现有产品表面改性、极端环境应用镀层、环保高效的中间层系统以及新型多功能薄膜和复合薄膜.该技术目前正在走向工业化.工业化应用面临的主要问题是产品和市场定位问题.     

低压冷喷涂铸造缺陷修复涂层性能研究

低压冷喷涂(LPCS)是一种拥有便携式冷喷涂系统的涂层技术。例如DYMET304K系统就应用于这项涂层技术中。通常情况下,压缩空气作为冷喷涂工艺中的运载气体。低压冷喷涂适用于喷涂金属基陶瓷复合粉末,如Cu基、Ni基、Zn基、Al基添加Al2O3粉的复合粉。硬质陶瓷相主要起到清洁喷嘴、增加表面活性和喷丸强化的作用,该方法在尺寸修复领域中具有优势。在这个领域里,修复铸造加工中的缺陷和气孔是一个很热门的应用。例如,Zn基复合材料就适用于防止电化学腐蚀和修复机械损伤造成的尺寸差异。本文对Zn+Al+Al2O3,Zn+Cu+Al2O3和Zn+Ni+Al2O3等复合材料做了实验研究。Zn和Al在腐蚀环境中起到阴极保护的作用,而Cu和Ni也有助于提高材料的机械性能。经过对微观孔蚀电位反应和力学性能(硬度和结合强度)的研究发现,涂层具有相对致密的结构和耐蚀性能。Zn在复合涂层中对其它金属起到阴极保护的作用。此外,在Fe52型铁基材料上的涂层有着足够的力学性能,硬度和结合强度较高。这一类涂层在修复宏观的铸造缺陷上具有很高的潜在应用价值。     

碳化硅复合镍磷合金涂层的组织结构、显微硬度及腐蚀性能研究

镍基复合涂层是一项有望替代电镀铬涂层的先进绿色环保表面处理技术。 本文在铝合金表面制备了纯 Ni、 NiP及其与SiC复合涂层, 利用SEM、 EDS和XRD研究了Ni、 NiP及其复合涂层的微观形貌、 成分与组织结构, 利用显微硬度计与电化学工作站研究了其硬度与耐腐蚀性能。 研究结果表明： SiC 复合电镀纯镍涂层的表面较为 粗糙, SiC 复合电镀镍磷合金涂层中晶粒轮廓明显; 电沉积镍磷合金涂层的相结构包括晶体 Ni2P、 Ni12P5 和非晶 NiP。 铝合金基体表面 Ni-P 合金涂层的显微硬度显著高于纯 Ni 涂层, 引入 SiC 纳米颗粒形成复合涂层可提高其 显微硬度; SiC 颗粒有助于提高复合涂层在氯化钠溶液中的腐蚀电位, 降低腐蚀电流密度, 提高其耐蚀性能。     

The use of self-propagating high-temperature synthesis and argon-arc overlaying when strengthening the surface of products made of titanium alloys

A new method for the deposition of protective coatings (wear-resistant overlaying) that are 2 to 10 mm thick and more on the surface of titanium articles is suggested, developed, approved, and patented. The method, called “SHS-arc overlaying,” combines the exothermic synthesis of adding material (AM) and argon-arc overlaying, which proceed simultaneously with the deposition of the coating. AMs made of exothermic mixtures are developed. Using this new method, protective composite coatings for titanium articles are obtained. The physicochemical, microstructural, and exploitation properties of the overlaying are investigated. Its operational characteristics exceed the characteristics of standard samples by a factor of 1.5–2.0. This new technology can be recommended for the deposition of protective coatings on products of wide indentation made of titanium alloys.     

连铸机结晶器铜板失效分析及改进措施

为了提高结晶器的使用寿命,从分析铜板及表面涂镀层失效原因出发,对结晶器的设计、铜板材质的选择和表面强化技术等方面进行了研究和总结,针对结晶器铜板在使用中出现的问题提出了改进措施。对比银铜和铬锆铜金相组织并通过实验发现：铜晶界之间析出的富铬金属化合物是铬锆铜基体结晶器的热裂纹来源。研究各种合金电镀层、热喷涂层以及纳米复合镀层的内应力分布特点,优化了铜板涂镀层的生产技术,不依靠任何有机添加剂生成压应力的涂镀层,在国内外多个钢厂实际应用并取得良好效果。     

Powder metallurgy industry and managerial economics

The phase composition and structure of two-layer thermal-barrier metal-ceramic coatings applied by electron-beam vapor deposition in one process cycle are investigated. It is shown that the outer ceramic layer has a two-phase (monoclinic-tetragonal) structure and is characterized by an axial growth texture of columnar crystallites with prevailing <001> orientation. High-temperature isothermal annealing in an oxidizing medium increases the amount of the tetragonal constituent in the outer ceramic layer of the thermal-barrier coating. __________ Translated from Poroshkovaya Metallurgiya, Vol. 46, No. 7–8 (456), pp. 100–106, 2007.     

Structure of the molybdenum–carbon–copper composite coatings produced by electroexplosive spraying followed by electron-beam treatment

Electroexplosive Mo–C–Cu composite coatings are modified by a high-energy electron beam for the first time. Our studies demonstrate that the electron-beam treatment of the electroexplosive spraying layer that is performed under melting conditions leads to the formation of a structurally and concentration homogeneous surface layer.     

Effect of Production Parameters on the Structure of the Outer Ceramic Layer in Two-Layer Metal - Ceramic Coatings Prepared by Electron-Beam Deposition in One Production Cycle

The effect of production parameters for electron-beam deposition of two-layer metal - ceramic coatings in one production cycle on the structure and phase composition of the outer ceramic layer based on zirconium oxide stabilized with yttrium oxide is studied. It is shown that it is possible to obtain metal - ceramic coatings with the required functional properties in one production cycle.__________Translated from Poroshkovaya Metallurgiya, Nos. 3–4(442), pp. 41–48, March–April, 2005.     

Study on Anticorrosive Cerium Conversion Coating of Cf/6061Al Composite Surface

The optimum chemical passivation process of the rare earth metal (REM) conversion coating on the Cf/6061Al composite surface was introduced in this paper and its polarization curves properties were investigated. Ridge-like coatings were found by scanning electro microscope (SEM) observations, and the Al matrix and carbon fibre reinforcement were both coated with Ce conversion coatings, with some minor cracks. The energy dispersive spectroscopy (EDS) plane scan analysis indicates that the major elements in the coating are Ce, O, Si, Al and the Ce content reaches 47.48%(mass fraction). The Ce conversion coatings increase the corrosion resisting properties of Cf/6061Al composite, with a higher free corrosion potential (Ecorr) and a lower free corrosion current density (icorr) for the coated composite than those of the bare composite. And the Boehmite-treatment would enhance the corrosion resistance of the REM conversion coating. The cathodic polarization and anodic polarization were retarded by REM conversion coating, resulting in an improved corrosion resistance.     

Development of CeO2 nanorods reinforced electrodeposited nickel nanocomposite coating and its tribological and corrosion resistance properties

A simple electrodeposition technique was used to prepare Ni-CeO_2 nanorods composite coating(Ni-CeO_2 NRs) using Watt's nickel plating bath containing CeO_2 nanorods(NRs) as the reinforcement phase under optimized process conditions. The X-ray diffraction analysis(XRD) was used for the structural analysis of Ni-CeO_2 NRs composite coatings and their average crystalline size is ～22 nm for pure Ni and ～18 nm,respectively. The crystalline structure is fcc for the Ni-CeO_2 nanocomposite coatings. The surface morphology of the electrodeposited Ni-CeO_2 NRs composite coatings was analyzed by scanning electron microscopy(SEM). Microhardness of pure Ni and Ni-CeO_2 NRs composite coatings are found to be 253 HV and 824 HV, respectively. The inclusion of CeO_2 NRs increases the microhardness of Ni-CeO_2 NRs composite coatings. The corrosion resistance behavior of Ni-CeO_2 NRs composite coating was evaluated by Tafel polarization and AC impedance methods. It is revealed that CeO_2 NRs reinforced Ni matrix shows higher microhardness and corrosion resistance than existing reported electrodeposited pure Ni and CeO_2 nanoparticles reinforced Ni coatings.     

铝基TiC–TiB2自蔓延高温合成复合涂层的组织性能研究

以Ti粉、石墨粉、B₄C粉、聚四氟乙烯粉(polytetrafluoroethylene, PTFE)为原料, 采用反应熔覆技术, 结合自蔓延高温合成与真空消失模鋳造法, 在ZL205A铝合金表面制备出TiC-TiB₂复合涂层, 研究了固溶温度对基体和TiC-TiB₂涂层显微组织、硬度和热稳定性的影响, 为制备高耐磨性铝合金提供新的研究方向。结果表明: Ti-C-B₄C-PTFE体系的绝热温度的远大于1800 K, 自蔓延高温合成反应可自发进行; 通过真空消失模铸造ZL205A铝合金, 引发自蔓延高温合成反应, 在基体表面可形成TiC-TiB 2复合涂层。固溶热处理后TiC-TiB₂复合涂层表现出良好的热稳定性, 硬度为HB 285, 20 N载荷作用下的质量损失量为49.7 mg, 相对减少了90%, 大大提高了ZL205A铝合金表面的耐磨性。     

Properties of Cu–Mo Materials Produced by Physical Vapor Deposition for Electrical Contacts

Powder Metallurgy and Metal Ceramics - New Cu–Mo composite materials were produced by physical vapor deposition (PVD) using an L5 electron-beam unit. They were proposed as an alternative to...     

搅拌方式对镍磷基碳纳米管复合镀层减摩性能的影响

以碳纳米管作为增强相,通过化学复合镀方法制备了镍磷基碳纳米管复合镀层。在制备过程中采用三种不同的搅拌工艺,并对相应镀层的减摩性能进行比较。结果表明：与单一的超声波搅拌或机械搅拌相比,采用混合搅拌工艺能够得到减摩效果更好的复合镀层,在对偶件为GCr15钢的干摩擦条件下,其摩擦因数仅为0．05。     

Characterization and In Vitro Corrosion Investigations of Thermal Sprayed Hydroxyapatite and Hydroxyapatite-Titania Coatings on Ti Alloy

In the current investigation, hydroxyapatite (HA) powder was mixed with titania (TiO₂) in 50:50?wt?pct for depositing composite coatings on a Ti-alloy substrate using a thermal-spray coating technique. The coatings were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM)/energy-dispersive X-ray spectroscopy (EDS) analyses. The corrosion behavior of the coatings was studied by electrochemical corrosion testing in simulated human body fluid. After the corrosion testing, the samples were analyzed by XRD and SEM/EDS analyses. HA and TiO₂ (rutile) were the main phases observed in the developed coatings. Bulk HA coating was amorphous; however, the addition of TiO₂ effectively improved the crystallinity of HA in HA-TiO₂ coating. The SEM analysis confirmed the formation of a well-formed HA-TiO₂ composite coating. HA coating exhibited higher bond strength (67.8?MPa) compared with HA-TiO₂ composite coating (37.6?MPa). The electrochemical study showed a significant improvement in the corrosion resistance of the Ti alloy after the deposition of the coatings.     

组元粒度对AlSi包覆BN涂层组织性能的影响

本文制备三种不同粒度配比的AlSi包覆BN复合粉末,通过大气等离子喷涂制备AlSi/BN可磨耗封严涂层,对涂层的硬度,结合强度及涂层组织进行了研究,并通过试验研究了不同形态颗粒在喷涂沉积过程中的演变行为,试验表明,较细的AlSi包覆较小粒径的BN颗粒在喷涂过程中具有最好的沉积效果,BN损失最少,核心BN颗粒粗大的粉末沉积效果差,BN损失严重。     

Industrial operation of vacuum aluminum evaporators made in refractory compound alloys

Conclusions Vaporizing elements of various types and sizes are being produced from a TiB₂-TiC alloy in the Special Design and Technology Department of the Institute of Materials Science, Academy of Sciences of the Ukrainian SSR, and widely used in vacuum deposition plants for the application of aluminum coatings to glass, plastics, fabrics, paper, metals, and film and other coiling materials. The operating life of these VE's, which depends on the aluminum deposition process parameters, is 5–7 h with resistance heating, 10–18 h with electron-beam heating, and more than 100 h with indirect heating. The resultant condensate is free from impurities capable of affecting the electrophysical properties of films.Translated from Poroshkovaya Metallurgiya, No. 1(157), pp.40–47, January, 1976.     

SiCp/Al复合材料的研究方法现状

SiC颗粒（SiCp）增强铝基复合材料因其制备工艺灵活，热物理性能优异及可设计性等许多独特的优点而具有很好的应用前景。本文综述了SiCp增强铝基复合材料的研究和进展，阐述并比较了几种该复合材料的制备工艺，包括搅拌铸造法、压力铸造法、无压渗透法、喷雾沉积法、离心铸造法和粉末冶金法等。     

Effect of Electron-Beam Treatment on Wear-Resistant Coatings Applied by Electroexplosive Sputtering

TiC–Mo, TiC–Ni, TiB₂–Mo, and TiB₂–Ni coatings applied to the surface of Hardox 450 steel by electroexplosive sputtering are subjected to electron-beam treatment, After electroexplosive application, the surface relief of the coatings includes features such as deformed solidifying microglobules, buildup, microcraters, microcracks, and peeling. After electron-beam treatment, the microglobules, buildup, microcraters, and microcracks disappear from the coating surface. A polycrystalline structure containing cellular elements is formed. After electron-beam treatment, the surface roughness is 1.1–1.2 μm. The thickness of the layers modified by the electron beam in the electroexplosive coatings depends linearly on the surface energy density. The greatest coating thickness is observed when using the TiB₂–Mo system; the coating thickness is least for the TiC–Ni system. That may be attributed to the thermophysical properties of the coatings. The following substructures are observed in the coatings: cellular, striated, fragmented, and subgranular. Grains with chaotically distributed dislocations and reticular dislocations are also observed. Electron-beam treatment leads to the formation of composite filled structure over the whole cross section of the remelted layer. The structure formed in this layer is more disperse and uniform than in coatings formed without electron-beam treatment. The inclusions of titanium carbide or titanium diboride in the molybdenum or nickel matrix are 2–4 times smaller than immediately after electroexplosive sputtering. Within the molybdenum or nickel grains and at their boundaries, rounded particles of secondary phase (titanium carbide or titanium diboride) are observed. They may be divided into two classes by size: particles of the initial powder (80–150 nm) that have not dissolved on irradiation; and particles formed on solidification of the melt (10–15 nm). In the electroexplosive powder coatings, the structure is mainly formed by dynamic rotation of the sprayed particles, which form a vertical structure both in the coating and in the upper layers of the substrate. The coatings have excellent operational properties: nano- and microhardness, elastic modulus of the first kind, and wear resistance in dry slipping friction.