热喷涂钴基合金涂层的耐气蚀性能

评价了用于耐蚀涂层的热喷涂钴基合金涂层的抗气蚀性能。钴基合金涂层分别用低压等离子喷涂(LPS)和高速氧燃料气火焰喷涂(HVOF)喷涂在AISI304不锈钢基体上,其中每种涂覆试样的一半试样进行了1073K×1h的后续加热处理。在本试验中,为了进行评价而测量了试样的重量损失。由气蚀试验得到如下结果:1)用LPS喷涂的两种涂层(喷后加热处理的和喷涂态的)比HVOF涂层具有更优越的抗气蚀性能;2)对于LPS喷涂层,喷后加热处理过的涂层与喷涂态的涂层具有相同的重量损失;3)对HVOF涂层喷后热处理非常有效地改善了抗气蚀性能。     

材料及防护涂层在淡水环境中的腐蚀试验研究

在三门峡水库和“635”水库中投放涂层和材料试样进行试验,考察了金属涂层、封闭涂层、复合涂层系统在两种淡水环境下的腐蚀情况,比较了喷锌、喷铝、锌铝合金、稀土铝等金属涂层和封闭涂层在淡水环境中的保护效果;取得了部分碳钢、不锈钢、有色金属材料在淡水环境中的自然腐蚀数据。     

树脂基复合材料用陶瓷涂层防护性能分析

采用等离子喷涂铝粉作为打底材料在碳纤维增强聚酰亚胺复合材料（PMC）基体上制备了Al2O3和ZrO2轻质陶瓷防护涂层，测试了涂层的剪切结合强度、耐热循环性能、抗冲蚀性能、隔热性能。结果表明，等离子喷涂铝粉作打底层的涂层系统，性能优于电弧喷铝或电弧喷锌作打底层的涂层系统。带有Al2O3涂层的试样失重不到基体材料失重的1／3，Al2O3和ZrO2陶瓷涂层都可以为聚酰亚胺复合材料基体提供有效的冲蚀防护。Al2O3和ZrO2陶瓷涂层都可以为聚酰亚胺复合材料基体提供有效的隔热防护，ZrO2涂层隔热性能优于Al2O3涂层。     

喷涂金属层长效防腐蚀机理的证明

40多年前,我国开始在淮河闸门上使用喷锌保护钢结构,以后几十年中,喷铝层、先喷锌后喷铝双层工艺均获得应用,最近用大功率二次风喷涂,得到高含铝量的锌铝伪合金长效防腐蚀涂层。中外合作进行了长周期(16000h)中性盐雾加速试验,证明了该防蚀涂层的长效性能。针对美国学者提出的三氧化二铝在涂层背面形成网络,氧化锌颗粒填塞网格,形成耐腐蚀氧化物层,通过扫描电镜试验,分别测出涂层背面的铝、锌和氧化物的含量,证明在背面化学成分中铝和氧化物总原子含量达到70%,因而解释了为什么大功率二次风喷涂的锌铝伪合金耐腐蚀层能够长效。     

Fe04基一次喷涂粉等离子喷涂层的形成特征与性能

制备了由FeO4粉、Ni／Al粉和超细铝粉组成的FeO4基一次喷涂粉末，用抛光至镜面的试样研究了喷涂层的形成特征，用XRD、SEM对其等离子喷涂层的组织与相结构进行了分析。结果表明：FeO4基一次喷涂层中出现FeO4高温生成相Fe13Mo2B5，涂层与基体的结合为机械、微冶金结合；其结合强度比FeO4等离子喷涂层提高了93.2％，耐磨性比FeO4喷涂层提高了84％。     

AZ91D镁合金电弧喷涂铝锌工艺的研究

选择不同的喷涂工艺参数,在镁合金表面喷涂铝锌丝材。采用中性盐雾试验,对不同工艺参数得到的涂层的耐腐蚀性进行了比较。结果表明电弧喷涂铝锌工艺参数对涂层质量有一定影响。试验确定的最佳喷铝锌工艺参数:电压27V,喷涂电流100A,空气压力0.5MPa,喷涂距离100mm。     

含稀土元素的耐海水腐蚀涂层研究

研制了含稀土元素的铝、锌、铝锌合金热喷涂金属线材，采用火焰喷涂后，喷涂层的结合强度、耐腐蚀性大大提高，孔隙率降低，尤其是铝稀土涂层值得大力推广。     

含稀土元素的耐海水腐蚀涂层研究

研制了含稀土元素的铝、锌、铝锌合金热喷涂金属线材．采用火焰喷涂后，喷涂层的结合强度、耐腐蚀性大大提高，孔隙率降低，尤其是铝稀土涂层值得大力推广。     

热镀锌沉没辊的耐锌腐蚀失效过程

采用超音速火焰喷涂技术在316L不锈钢基体上制备WC-12Co涂层,并测试其在430℃锌液中的耐腐蚀性,分析沉没辊的腐蚀机理以及失效过程。采用SEM、EDS和XRD分析了腐蚀前、后涂层表面显微结构、化学成分及其相组成的变化。结果表明,WC-12Co粒子之间通过高速碰撞发生强烈的塑性变形而结合在一起,涂层内部致密性很好,喷涂过程中没发生明显氧化现象;涂层的显微硬度平均为1 215HV0.2,结合强度达到85MPa;无涂层试样在腐蚀59h后直径减少20%;经过10天的浸锌试验后,涂层开始产生均匀性腐蚀,涂层中的Co基体受液锌腐蚀生成Co5Zn21化合物,涂层开始遭到破坏;经过15天浸锌试验后,部分锌液穿过涂层与基体中的Fe化合生成FeZn13(即锌渣),涂层局部开始脱落,涂层失效开始。     

电弧喷涂长效防腐技术在煤矿钢结构上的应用

正中国矿业大学的电弧喷涂长效防腐技术在煤矿井筒装备和钢井架长效防腐领域已得到大力推广应用。电弧喷涂防腐原理是利用电弧喷涂设备,对2根带电金属铝丝或锌丝进行加热、熔融、雾化、喷向钢构件表面形成金属防腐涂层。该涂层与其他传统防腐涂层相比具有以下突出优点:①与金属基体结合牢固,电弧喷铝涂层平均结合力达15MPa以上,金属喷涂层以机械镶嵌和微冶金方式与基体金属相结合     

Protecting stainless steel by glass coating during slab reheating

A glass coating was prepared onto AISI 304 stainless steel by a slurry-spraying technique and its effects on oxidation behavior of this steel was investigated at 1250 °C in air. Results were compared with those for bare specimens. The glass coating decreased the weight gain by 98% after oxidation for 9 h, and oxidation kinetics of 304 stainless steel was changed to linear behavior due to the coating. Steel loss of the coated specimens was reduced by 1-2 orders of magnitude. Hot stage microscopic, optical, XRD and SEM-EDX analyses revealed that the as-received coating melted at high temperature, to form self-healing, homogeneous glass coating which acted as a perfect oxygen diffusion barrier and prevented the breakaway oxidation of 304 stainless steel. During cooling, the glass coating spalled because of CTE mismatch between coating and the steel. This glass coating by low-cost and easy handling method is potentially applicable during slab reheating of stainless steel.     

Sintered Cu Alloyed Stainless Steels and Their Corrosion Behavior

Copper is an effective element to activate the sintering process of stainless steels and to enhance corrosion resistance of the sintered specimens. Ways of introducing Cu into stainless steel powders lead to different consequence in the microstructure and corrosion behavior of sintered Cu alloyed stainless steel. In the present work, two methods, mixing Cu with stainless steel powder and coating stainless steel powder with Cu by electroless plating, were introduced in order to investigate their influence on the sintered specimens. It was found that the sintered specimens from Cu-coated stainless steel powders (1-5 wt.%Cu) produce less porous surfaces with isolated pores than the specimens from mixed powders and the former have obviously high density and relatively even Cu distribution. Potentiodynamic polarization measurements indicate that Cu-electroless plating of 1-5 wt.%Cu improves the corrosion resistance of sintered stainless steel due to the lowering of passivation current density.     

A study of corrosion of welded steel specimens in a marine atmosphere,with and without protective coatings

The corrosion of mild steel and stainless steels of the Type AISI 304 and 316 with and without welding has been studied in a marine atmosphere together with some samples of mild steel with a magnetite coating. The corrosion rate has been determined in each case by loss in weight of the specimens and the nature of corrosion has been examined by X-ray diffraction and microscopy. The corrosion rate of mild steel is much more than that of stainless steel. Gas-welded specimens were found to corrode more quickly than arc-welded samples. Magnetite coatings properly bonded to the metal surfaces reduce the rate of corrosion considerably.     

A study of zinc phosphate coatings on 12·5Cr–21·0Ni stainless steel

Abstract

12·5Cr–21·0Ni stainless steel was chemically treated with zinc phosphate in order to find the most suitable phosphate solution and its operating parameters. The phosphate coatings were tested for their corrosion protection of stainless steel using three methods: the salt spray test, the humidity cabinet test and the brine immersion test. The phosphate coatings were also mechanically tested using a tensile test for determining their mechanical properties. Results clearly show that phosphate coatings with a uniform appearance and full coverage can give high corrosion protection to 12·5Cr–21·0Ni stainless steel by forming a physical barrier against the corrosive environment. The 12·5Cr–21·0Ni stainless steel after coating with zinc phosphate still retains reliable mechanical properties, thereby providing valuable applications in the engineering field.     

Effect of current density on DC electrochemical phosphating of stainless steel 316

In this study, tri-cation phosphate coating of zinc, calcium and iron was applied electrochemically to stainless steel 316 substrates. Cathodic current was used as an accelerator for the phosphating process. The effects of current density on the microstructures of the coatings and the time necessary for the reduction of the oxide layer have been established. For this purpose, analyses such as chronopotentiometery, SEM, EDS and linear polarization were carried out. Results indicated that higher electrophosphating current densities result in finer crystal size of the coating. This effect is detrimental to the quality of the layer. In addition, chemical analyses of the layer revealed that the use of current for electrophosphating of stainless steel 316 substrates imparted better corrosion resistance to the substrate as a result of zinc rich crystal deposition in the phosphate layer.     

Hydrogen entry behaviour of newly developed Al–Mg–Si coating produced by physical vapour deposition

A ternary Al–Mg–Si alloy was prepared by co-evaporation technique and tested with respect to hydrogen entry behaviour as an alternative to conventional zinc coating on steel. Hydrogen entry behaviour evaluated using Devanathan cell showed a smaller hydrogen entry for this new coating than conventional zinc coating. Compared to an unscratched surface, hydrogen entry increased by more than 100 times in the scratched surface, but it was lower than that for the zinc coating with a scratched surface owing to the moderate galvanic corrosion potential of the new coating. This new coating is proposed especially for high-strength steel application.     

Resonant-based identification of the elastic properties of layered materials: Application to air-plasma sprayed thermal barrier coatings

This work introduces a resonant-based, mixed numerical–experimental method for the determination of the in-plane elastic properties of the constituent materials of laminates. This non-destructive method identifies elastic properties from the resonant frequencies of beam-shaped layered specimens, using a set of finite element models. The method is demonstrated on a thermal barrier coating system made of NiCoCrAlY bondcoat and yttria-stabilised zirconia topcoat deposited by air-plasma spraying on stainless steel. The stainless steel was found to be elastically anisotropic, while both bondcoat and topcoat exhibited in-plane isotropy. Moreover, the topcoat Poisson's ratio approached zero, and the bondcoat properties varied with the coating thickness. Scanning electron microscopy was used to correlate the identified elastic properties with the coating microstructure.     

The Effect of NiAl Coatings on Oxidation Behavior of AISI 403 Stainless Steel

STAINLESS STEEL TYPE AISI403possess a highdegree of resistance to atmospheric corrosion becauseof its ability to form a dense adherent oxide film,whichprotects the material from further attack[1].Thiscomposition was developed to meet the requirementsfor some gas turbine components.The alloy is notparticularly recommended for use in hot corrosion andoxidation environments.Therefore,a protective coatinglayer is essential for such applications as hot sectioncomponents in gas turbine[2].A…     

复合电镀法制备Ni-WC纳米涂层的组织与性能研究

为了制得高硬度、高耐腐蚀的纳米复合涂层,采用复合电镀法在18-8不锈钢基体上制备了Ni-WC纳米镀层,并对镀层的表面形貌、显微硬度及耐蚀性进行了观察和检测.试验结果表明:复合镀层表面均匀,其显微硬度较不锈钢和纯镍镀层都有显著提高,耐蚀性约为不锈钢的4倍,却比纯镍镀层略低.     

表面抗菌不锈钢的研究进展

抗菌不锈钢是一种新型的抗菌材料,拥有抗菌性强、耐高温塑性好、自身无菌等良好的特性,在医疗、食品、公共卫生等领域有很好的应用前景.在实际应用中,抗菌不锈钢主要应用其表面的抗菌性能,因此,表面抗菌不锈钢较之其他产品有更高的研究价值.综述了表面抗菌不锈钢的研究进展,主要包括表面涂层型抗菌不锈钢和表面改性型抗菌不锈钢的制备工艺,以及不同类产品的抗菌能力.结果表明,目前表面抗菌不锈钢在制备及使用过程中所面临的问题主要是对生产设备和技术要求高,产品耐磨性差,当前的技术难以达到大量制备表面抗菌不锈钢的要求.结合电沉积法的特点及扩散特性,以及利用电沉积扩散法在制备抗菌不锈钢方面的应用情况,指出利用电沉积扩散法在不锈钢基体表面制备抗菌镀层将是未来制备表面抗菌不锈钢的主要发展方向.