Single- and Two-Layer Coatings of Metal Blends onto Carbon Steel: Mechanical, Wear, and Friction Characterizations

Single- and two-layer coatings were deposited onto carbon steel using a high-velocity oxy-fuel deposition gun. The two-layer coating consisted of a top layer of tungsten carbide cobalt/nickel alloy blend that provides wear resistance and a bottom layer of iron/molybdenum blend that provides corrosion resistance. The morphological changes in the single- and two-layer coatings were examined using scanning electron microscopy. The residual stresses formed on the surface of various coatings were determined from x-ray diffraction data. Nanomechanical properties were measured using the nanoindentation technique. Microhardness and fracture toughness were measured incorporating the microindentation tests. Macrowear and macrofriction characteristics were measured using the pin-on-disk testing apparatus. The goal of this study was to ensure that the mechanical properties, friction, and wear resistance of the two-layer coating are similar to that of the single-layer coating.     

Conversion Coatings on Composite Metal Articles

The usual phosphating and chromating methods employed for individual steel, zinc and aluminium differ from one another with regard to treatment time, temperature and specific bath composition. Thus they cannot be used for treating composite metal articles. Zinc phosphate solutions containing only minor amounts of fluoride ions can be used for treating articles where the proportion of aluminium surface, based on the total area, is not greater than about 5%. By increasing the fluoride content a new solution has been developed which permits the production of fine-grained, dense, homogeneous and strongly corrosion-resistant coatings on work-pieces comprising any arbitrary proportion of the total surface area in the form of steel, zinc or aluminium.     

Plasma Sprayed PMMA Coatings on Steel

PMMA coatings have been applied to steel by plasma spraying. The work shows that the polymer decomposition temperature is a function of the particle residence time in the plasma and is much higher than in conventional polymer processing. The analysis indicates that realistic prediction of the temperature profiles of in-flight polymer particles can only be obtained by using this dynamic decomposition temperature. The process model predicts that only the surface layers of the polymer feedstock particles undergo significant decomposition under optimized spraying conditions.     

New Protective Coatings for Replacing Cadmium Coatings on Steel Parts

Works aimed at solving the problem of replacing toxic cadmium coatings used for protection of aircraft steel parts are reviewed. Numerous electrolytic alloys based on zinc and zinc-bearing coatings of the Colsil and Dacromet types are suggested for the purpose. A VIAM-designed coating based on a Zn – Sn alloy in combination with a modified phosphate coating is considered. It is shown that the protective properties of the combined coating are close to those of a cadmium coating, and the former is recommended for commercial use.     

钛的锻造

综述了增强相涂层种类、涂层制备方法及其对金属基复合材料界面和性能的影响。根据涂层的功能将涂层分为润湿涂层、阻挡涂层和调节界面涂层。对化学镀、化学气相沉积、溶胶－凝胶法及其它涂层制备方法作了扼要讨论。也介绍了单涂层、双涂层及复合涂层对金属基复合材料界面及性能的影响。     

Metal Coatings for Corrosion Prevention

Abstract

In order to obtain well-defined Mössbauer spectra of oxide films on low-carbon steel, it is beneficial to separate the films from the substrate. Chemical stripping in a solution of iodine in methanol in dry and oxygen-free conditions enables the oxide films to be separated without changing their composition and structure. The only by-product is cementite extracted from the low-carbon steel substrate during stripping. The Mössbauer transmission spectra obtained from the stripped oxide films yield information on the phase composition of the films and on deviations from stoichiometry of iron oxides present in the films.     

金属橡胶表面沉积镍基纳米TiN复合镀层的研究

采用超声一电沉积的方法,在金属橡胶上制备镍基纳米TiN复合镀层.利用平磨机、扫描电镜SEM)和能谱仪(EDS)研究复合镀液中TiN粒子的悬浮量、电流密度以及超声波功率等参数对镍基纳米TiN复合镀层耐磨性能的影响规律,并对金属橡胶和复合镀层进行成分分析.结果表明:复合镀液中TiN粒子的悬浮量、阴极电流密度和超声功率对复合...     

用于燃气锅炉低碳钢耐冲蚀—腐蚀磨损的双层热喷涂层

为防护发电厂锅炉的热交换器管道的腐蚀冲蚀磨损,研究开发了一种热喷涂层涂层（高速火焰喷涂Cr3C2/TiC-25NiCr涂层＋电弧喷Ni21Cr9Mo35Nb涂层）,在锅炉管道上实际应用两年后,对这种双涂层进行冲蚀试验和金相分析,并对其性能进行讨论。结果发现,燃烧电弧喷涂Ni21Cr9Mo3.5Nb涂层在高硫及环境中是一种良好的防护涂层。     

低成本制备铁基金属表面防腐蚀无机涂层

研究了碱(水玻璃)激发高纯度的偏高岭土作为金属表面的防腐蚀水性涂层的可行性,初步确定了水玻璃的模数、总固含量、适用环境以及固定剂和增强剂的种类.当水玻璃的模数n=1.5,固定剂为ZnO,总固含量在67%～71%时,涂膜在适宜养护环境下养护5d后的硬度可达8H铅笔硬度,用划格法测量粘着力可达1级.在自来水、海水、稀酸、稀碱和硫酸钠溶液中存放40d没有明显腐蚀.用SEM观察涂膜,发现涂膜中有硅铝酸网状结构的产物组成,外加剂分散在网格中,形成了致密的膜.     

Protective Bauxite-Based Coatings and Their Anti-decarburization Performance in Spring Steel at High Temperatures

A decarburization protective coating was fabricated onto spring steel by using bauxite with functional additives. Metalloscope, XRD, and TG-DTA thermal analysis revealed that, at <1050 °C, the depth of the ferrite layer of the coated specimen decreased because of the shield effect and carbon concentration of the coating. The protective effect increased to 100% above 1050 °C, because Na₂Al₆P₂O₁₅ formed by the sintering process pulled the solid phase closer and filled the void through wetting power and surface tension between the liquid and solid phases and made the coating more compact.     

合金钢热障涂层等离子喷涂及高温力学特性研究

目的研究等离子喷涂热障涂层微观组织与高温力学性能,为热障涂层在合金钢的应用及其失效机制提供理论支撑。方法采用等离子喷涂技术在30Cr Mn Si A钢基体上制备Ni Co Cr Al Y/YSZ热障涂层,利用扫描电镜显微观察、物相分析、热震试验、拉伸试验等技术方法,考察涂层在高温条件下的失效行为。结果合金钢等离子喷涂热障涂层为典型双层层片状结构,YSZ涂层仅含有稳定四方相。800℃时,涂层试样拉伸试验后的断裂载荷与无涂层试样相比高10%。热障涂层的抗热震性良好,经900℃热震循环试验10次后,涂层完好;经1000℃热震循环6次后,涂层剥落失效,剥落面位于粘结层与基体之间。热震循环过程中,钢基体被氧化甚至腐蚀。涂层试样边缘产生应力集中,随着热震次数的增加,裂纹逐渐扩展,最终导致涂层成块剥落。温度由700℃升至900℃,Ni Co Cr Al Y涂层硬度下降幅度大于YSZ涂层和30Cr Mn Si基体。结论粘结层与钢合金基体的热膨胀不匹配是导致热震试验涂层剥落的主要原因。热障涂层的隔热作用使涂层试样的基体温度较低,导致其断裂载荷与无涂层试样相比较高。     

Aluminide Coatings Formed on Fe–13Cr Steel at Low Temperature and its Oxidation Resistance

A novel aluminizing process has been developed to produce aluminide coatings on Fe–13Cr stainless steel at a much lower temperature (520–600 °C) and with a shorter time (60–240 min) compared to the conventional pack-aluminizing processes. In this process, chemical reaction and atomic diffusion were accelerated by ball impact generated by mechanical vibration. The effects of operation temperature and duration on the coating thickness were studied. Scanning-electron microscopy (SEM and EDS) showed that the coatings appeared to be dense, homogeneous, free of porosity and with excellent adherence to the substrate. X-ray diffraction (XRD) analyses indicated that the coatings consisted mainly of η-Fe₂Al₅ and θ-FeAl₃. High-temperature oxidation tests were carried out in air at 900 °C. The results indicated that the aluminide coatings obtained from this process have significantly improved high-temperature oxidation resistance.     

New Tool Coatings for Light Metal Cutting

REDUCTION of fabrication costs and more and moreextended regulations for environmental protection arethe main reasons for going to dry machining in metalcutting applications.For example costs forcooling/cutting liquids may rise to8-16%of themachining costs[1].Dry machining of al-alloys is especially difficultbecause of the tendency of aluminium to stick to thecutting tools.This results in formation of built up edge(BUE)and makes removal of aluminium chips from theflute of the cutting tool …     

抗磨性非晶和纳米晶钢合金

美国爱达荷州国家工程和环境实验室的科学家们研究了非晶态和纳米晶钢合金的制取及其特性。研究用的非晶、纳米晶钢合金的成分 ,是根据能够以较低的冷却速度 (10 4 Ｋ/ｓ)形成金属玻璃的基本原理来设计的Ｆｅ6 3Ｃｒ8Ｍｏ2 Ｂ17Ｃ5Ｓｉ1Ａｌ4 。采用了两种方法来制备这一钢合金     

耐火粉料对金属型涂料性能的影响

研究了硅藻土、莫来石、滑石粉、白刚玉4种不同耐火粉料对金属型涂料悬浮率、强度、条件粘度、发气量、触变性的影响。实验结果表明:硅藻土是影响涂料悬浮率、发气量和强度的最显著因素;莫来石可以有效提高涂料的悬浮率及粘度;滑石粉是影响涂料条件粘度的最显著因素;不同的粉料组成对涂料的流体形态及条件粘度影响较大。     

Deposition and Properties of Phosphate Coatings on Galvanized Steel

It is shown that protective films on galvanized steel can be obtained from alkaline phosphate solutions in the presence of phosphorus-containing ligands. The samples are suggested to be treated in these solutions prior to application of crystalline phosphate coatings. The films obtained are compared with crystalline phosphate coatings by using scanning electron microscopy (SEM) and x-ray diffraction (XRD) methods.     

防止呋喃树脂砂厚大铸钢件粘砂缺陷的新型涂料和面砂研制

新研制的水基锆英粉涂料包括底涂料和面涂料。底涂料具有较好的涂渗性，涂渗深度达到2．6mm，它既有填隙作用，又可减缓砂型的激热膨胀，面涂料具有较好的厚涂性，单次刷涂的干厚度达到1．1mm，具有较好的抗金属液冲刷和侵蚀特点，新开发的Z－1砂是1种粒形圆整，表面光洁的铝硅系耐火材料，具有热膨胀率小，树脂耗量低和能适度烧结的特点，生产试验表明，配合使用上述Z－1砂和新型双层涂料，能有效防止呋喃树脂砂厚大铸钢件的金属渗透。     

金属表面耐高温防腐涂料的研究进展

长时间处于高温环境中,金属易发生氧化腐蚀,从而丧失机械性能直至破坏,严重影响了使用效能的发挥。在金属表面涂覆耐高温涂层,因施工简便、成本较低、耐热性能好等优点而获得广泛应用,对于防止材料高温腐蚀、节约资源等具有重要的经济意义。对目前常用的耐高温涂料进行分类,包括有机耐高温涂料和无机耐高温涂料两大类,重点介绍了有机硅树脂耐高温涂料和无机耐高温涂料,并简单描述了有机-无机复合耐高温涂料的有关情况。对不同类别耐高温涂料的化学组成、物理性能和耐热机理等进行了阐述,并结合涂料的结构特点对各自优缺点进行了分析与比较。根据耐高温涂料在现代工业发展中的重要作用,介绍了国内外关于耐高温涂料的研究进展和应用情况,指出了不同类别耐高温涂料在使用过程中存在的问题。最后结合当前工业社会向信息化社会转变的时代背景以及研究耐高温涂层的技术意义,对耐高温涂料的发展趋势进行了展望。     

Organic Protective and Decorative Coatings for Metal Containers

The adhesion of paint to metal is affected by the nature and condition of the metal surface at least as much as by the nature of the paint. Paints of all types appear to adhere well to most very clean metals but the adhesion of some paints is sensitive to extremely low levels of contamination—for example, by stearic acid. Non-polar hydrocarbon contaminants do not reduce adhesion seriously unless they are present in amounts sufficient to weaken the cohesion of an interfacial layer. The surfaces of almost all commercial metal sheets are contaminated and require pretreatment before painting. The nature of the contaminants present are discussed and laboratory techniques for obtaining cleaning surfaces are reviewed.