沉没辊表面抗液态锌腐蚀材料的研究

着重介绍了液态锌液对金属的腐蚀机制,对耐锌蚀材料及表面改性方法研究进行比较分析,并对耐液态锌腐蚀材料的发展趋势进行展望.结果表明热喷涂WC/Co、Al2O3、ZrO2-Y2O3、MoB/CoCr等涂层材料能有效提高抗锌液腐蚀能力,其中超音速喷涂MoB/CoCr涂层的性能最为突出,抗锌液腐蚀能力达600多小时,是有望成为提高沉没辊使用寿命的涂层材料.     

沉没辊表面抗锌液腐蚀材料的研究

采用钼粉、硼铁粉、铬粉为原料烧结制备了一种三元硼化物陶瓷复合粉末,并采用超音速喷涂制备了致密的热喷涂涂层,研究发现涂层的力学性能和FUJIMI公司CoCr/MoB涂层相近,经过两周的高铝锌液腐蚀试验,发现涂层在高铝锌液中具有良好的耐腐蚀能力,作为耐锌腐蚀涂层材料具有非常好的应用前景。     

熔融锌对热镀锌沉没辊的浸蚀机理及对策

简要综述了热镀锌带钢生产线沉没辊的工作情况及腐蚀机理,对国内外耐液锌腐蚀的材料以及表面防护技术作了较为详细的介绍,指出热喷涂涂层可以有效地减缓锌的腐蚀,并且耐高温无机封孔剂可大大提高热喷涂层耐液锌腐蚀性能,并提出了未来沉没辊耐液锌腐蚀的研究方向。     

热喷涂制备ZnAl涂层防腐性能研究

以锌粉和铝粉为原料,采用热喷涂工艺在A3钢板上制备TJPTZA1、TJPTZA2、TJPTZA3和TJPTZA4涂层.研究了不同涂层以及纯锌、纯铝抵抗海水的腐蚀能力.采用盐雾分析法分析不同涂层的耐腐蚀程度,采用高倍显微镜观察不同腐蚀时间的薄膜表面形貌.结果表明:TJPTZA2、TJPTZA3的耐腐蚀性好于Al和Zn,认为是锌铝合金热喷涂层中的锌铝原子相互作用减缓了氯离子等物质的腐蚀.     

防高温锌液腐蚀涂层的研究

防锌腐蚀涂层的工业试验表明：研制的热喷涂保护层具有耐高温锌液浸渍腐蚀、耐急冷急热的特点。在锌液冷却管上应用可提高冷却管的使用寿命７～ｌ０倍。该项技术可推广应用于锌冶金和热镀锌行业。     

高铁接触网零部件超细片状锌铝防腐涂层应用研究

目前接触网典型金属件表面防腐技术各具优势的同时也各有弊端。本文主要对电弧喷涂超细片状锌铝涂层防腐新技术的保护膜形成与耐腐蚀机理进行阐述，并根据实际应用情况提出目前常用的金属表面防腐方法的不足。后续应用该防腐方法分别对材质为铝合金、碳钢和铜合金的典型高铁接触网零部件进行多种腐蚀试验。通过试验验证了电弧喷涂超细片状锌铝涂层具有优异的金属表面防腐性能，并且证明该技术在金属表面防腐领域具有一定的优势，为高铁接触网零部件表面防腐提供了更好的选择。     

用于海洋环境下活化腐蚀防护的高性能电弧喷涂层

采用铝或锌涂层的活性腐蚀防护是热喷涂技术应用最多的领域.每年大约要消耗20,000吨的喷涂线材,并且未来需求还在增加.热喷涂技术及材料无论是单独还是一起在海洋环境下使用,都有一定的标准.海上风力发电机（OWET）要求维护间隔时间尽可能长,这可以通过使用长寿命的表面涂层来满足使用要求.目前,金属喷涂涂层主要用于OWET的高应力部件,如法兰、框架和安装面.在实验室测试的过程中,研究了多种用于OWET的双涂层体系的抗腐蚀效果,其中金属涂层关注最多.制备了不同厚度和特性的Zn/A1和Al涂层,对部分涂层进行封孔处理,并制备有机涂层形成多层涂层体系.其目的之一是制备地氧含量的防护涂层,并和目前标准的工艺进行对比.依照ISO20340标准[5]对涂层和标样涂层的抗腐蚀性能进行了25周的循环老化测试评价,评估标准为：涂层划痕处的腐蚀和渗透、涂层起泡和锈蚀程度,以及涂层与基材的结合力.测试结果表明,喷涂金属涂层是一种有效的改善材料的抗腐蚀性能方法.采用活性气体作雾化气体的电弧喷涂或冷喷涂制备Zn/A115涂层能够提升涂层的防护效果,并且可以降低涂层的厚度,具有较好的经济前景.     

热喷涂锌、铝长效防腐蚀涂层及其在钢铁构件上的应用

介绍了热喷涂锌、铝长效防腐蚀涂层的防蚀机理和应用实例,及以不同防蚀方案的长期经济效益比较。指出：热喷涂锌、铝长效涂层是目前保护钢铁构件使用安全的最为科学、经济的方法。     

面向垃圾焚烧炉应用的抗高温氯腐蚀涂层技术

焚烧是市政垃圾最为有效的处置方式。然而,垃圾焚烧气氛产生的腐蚀及磨损对锅炉安全运行存在极大的风险。采用功能涂层技术隔绝锅炉管与腐蚀气氛,从而实现对管壁的保护,是可行方案。本文对比了熔覆、耐火材料及热喷涂等防护方案,最终采用电弧喷涂制备耐氯腐蚀涂层,通过分析涂层的基本性能、锅炉内现场施工及实际焚烧环境运行等多方面,验证了采用电弧喷涂对垃圾焚烧炉管防护的可行性。     

热喷涂涂层封孔处理及其耐蚀性能研究

研制了一种主要针对钢铁企业镀锌生产线沉没辊和稳定辊热喷涂层的复合封孔剂,其具有良好的耐高温腐蚀性能和抗粘锌性能。采用刷涂方法,对热喷涂涂层进行封孔处理,并对封孔处理的涂层进行酸腐蚀、锌腐蚀和抗粘锌试验。研究结果表明,涂层中的孔隙基本已经被封孔剂所填充,降低了涂层的孔隙率。封孔涂层可以屏蔽或减缓外部腐蚀介质对涂层及基体的渗透作用,从而起到有效的防护作用。并且该复合封孔剂具有很好的抗粘锌性能。     

热喷涂制备非晶合金涂层性能的研究进展

首先介绍了非晶合金的理论基础,然后从耐磨性和耐蚀性两个方面入手,详细地阐述了国内外对于热喷涂非晶合金涂层性能研究进展情况,并系统地总结了非金合金涂层在耐磨性和耐蚀性上的本质联系和根本矛盾,最后指出热喷涂非晶合金涂层性能研究上的局限性,提出三点问题:对于非晶合金基础理论的研究还处在起步阶段、热喷涂制备非晶合金涂层的合金体系种类少、制备非晶合金涂层的热喷涂技术有待开发,并针对以上三点问题提出热喷涂制备非晶合金涂层性能研究的未来发展方向。      

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。     

锌和镀锌钢的稀土表面改性

通过在Ce(NO_3)_3水溶液中对锌和电镀锌钢进行化学转化(钝化)处理,在试样表面形成了铈转化膜。利用电子探针显微分析(EPMA)、X射线光电子能谱(XPS)和X射线衍射(XRD)等研究了转化膜的形貌、成分和结构,探讨了锌表面铈转化膜的形成机理。在氯化钠溶液中测定了试样的腐蚀率、极化曲线和电化学交流阻抗谱(EIS)等腐蚀性能参量,并与未钝化和普通铬酸盐钝化试样的情况作了对比。结果表明,本实验得到的锌表面稀土转化膜主要是由CeO_2、Ce_2O_3和ZnO组成的复合氧化物膜,铈转化膜的存在阻碍了锌在电化学腐蚀过程中的阴极反应和阳极反应,导致电荷传递电阻增大,腐蚀率降低。在一定条件下,铈转化膜对锌和镀锌钢的肪蚀效果优于铬酸盐转化膜。     

超音速火焰喷涂鉄基粉末涂层取代硬镀铬在印刷行业的应用

目前,在印刷行业采用HVOF喷涂铁基合金涂层取代硬镀铬处理印刷辊成为必然的趋势。首先,采用喷涂AISI316L材料在此应用领域基本上可满足其抗腐蚀条件。不过,AISI316L材料的耐磨损性能却不能满足其应用环境。采用GTV公司的K2喷涂系统,使用两种不同的高铬含量和高硼含量硬合金材料可以达到更高的耐腐蚀性能和同等的抗磨损效果。当然,喷涂参数以及喷涂颗粒的状况和涂层的显微组织结构都需要进行优化。下文中对本涂层的耐磨和抗腐蚀性能与AISI316L材料和硬质合金材料进行了比较。新开发的铁基硬合金材料涂层的平均硬度可达850HV0.3。与传统的AISI316L涂层相比,在进行盐雾试验和摩擦磨损试验中,铁基合金材料涂层的耐腐蚀和抗磨损性能要高得多。试验结果得到证实,并且在目前全球顶尖的印刷设备生产商开始正式的投用。     

Comparative High-Temperature Corrosion Behavior of Ni-20Cr Coatings on T22 Boiler Steel Produced by HVOF, D-Gun, and Cold Spraying

To protect materials from surface degradations such as wear, corrosion, and thermal flux, a wide variety of materials can be deposited on the materials by several spraying processes. This paper examines and compares the microstructure and high-temperature corrosion of Ni-20Cr coatings deposited on T22 boiler steel by high velocity oxy-fuel (HVOF), detonation gun spray, and cold spraying techniques. The coatings’ microstructural features were characterized by means of XRD and FE-SEM/EDS analyses. Based upon the results of mass gain, XRD, and FE-SEM/EDS analyses it may be concluded that the Ni-20Cr coating sprayed by all the three techniques was effective in reducing the corrosion rate of the steel. Among the three coatings, D-gun spray coating proved to be better than HVOF-spray and cold-spray coatings.     

Surface Modification With Zinc and Zn-Ni Alloy Compositionally Modulated Multilayer Coatings

Zinc and Zn-Ni alloy compositionally modulated multilayer （CMM） coatings were electrodeposited on to a steel substrate by the successive deposition of zinc and Zn-Ni alloy sublayers from dual baths. The coated samples were evaluated in terms of the surface appearance, surface and cross-sectional morphologies, as well as corrosion resistance. The microstructural characteristics that were examined using the field emission gun scanning electron microscopy （FEGSEM） confirmed the layered structure, grain refinement of the zinc and Zn-Ni alloy CMM coatings, and revealed the existence of microcracks caused by the internal stress in the thick Zn-Ni alloy sublayers. The corrosion resistance that was evaluated by means of the salt spray test shows that the zinc and Zn-Ni alloy CMM coatings were more corrosion-resistant than the monolithic coatings of zinc or Zn-Ni alloy of the same thickness. The possible reasons for the better protective performance of Zn-Ni/Zn CMM coatings were given on the basis of the analysis on the micrographic features of zinc and Zn-Ni alloy CMM eoatings after the corrosion test. A probable corrosion mechanism of zinc and Zn-Ni alloy CMM coatings was also proposed.     

Understanding the Corrosion and Remedial Measures to Control the Deterioration of Reinforcement Steel Bars by Modification in Their Chemistry and Application of Surface Coatings

Corrosion of reinforcement bars embedded in structures near coastal areas is a serious problem and has been attributed to many premature distresses of structures. The passivity imparted by the alkalinity of the cement to reinforcement steel surface becomes ineffective when chloride concentration at the steel surface exceeds a critical threshold value. Under such a situation, the total loss of the steel thickness per unit area is negligibly small in comparison to penetration rate at certain susceptible part of the reinforcement bars. As a result of increase in stress intensity factor at the tip of localized pits formed on the surface of rebars, the tensile strength of the concrete structures which is mainly imparted by the steel reinforcement bars, is adversely affected and results in collapse of structures. Many techniques have been developed to control the corrosion problems associated with rebars. These include use of corrosion resistant alloys, corrosion inhibitors, cathodic protection and use of organic/metallic coatings on surface of steel bars. Amongst these techniques, the applications of surface coatings appear an effective and economical method to control corrosion of steel rebars. However, the efficacy and mechanism of their protective action are still matter of controversy and subject matter of studies all over the world. The present work is in continuation of our earlier studies published in different scientific journals where the above aspects had been addressed. This paper incorporates experimental results and literature review in understanding the corrosion and remedial measures to control the deterioration of reinforcement steel bars by modification in their chemistry and application of surface coatings. A brief historical background is given on development of reinforcement concrete structures. Various types of reinforcement bars used in construction industries and their merits and demerits are described. It has been established by the experimental proofs that the current scenario of protecting steel rebars used in chloride contaminated concrete, is not at all satisfactory. Amongst the protective coatings, metallic coated rebars appear to be more effective than organic based coatings. Causes and mechanism of deterioration of coated and bare steel rebars are discussed by providing experimental evidences.     

海港工程钢筋混凝土结构热喷涂阳极防护涂层技术

介绍了一种海港工程钢筋混凝土结构采用热喷涂阳极防护涂层技术来进行腐蚀防护的方法,就热喷涂防护原理、阳极涂层材料、施工工艺和质量控制等方面进行了分析和总结,也同时介绍了钢筋混凝土表面上热喷涂阳极涂层的修补技术和国外的应用实例。     

Effects of zinc coatings on the stress corrosion cracking and hydrogen embrittlement of low-alloy steel

The effects of electroplated and hot-dip zinc coatings on the fracture of low-alloy steel AISI 4140 bars tempered to hardnesses in the range Rc 33 to 49 were studied. Either electroplated or hot-dip zinc coatings decrease resistance to stress corrosion cracking,i.e., they reduceK _sc, the threshold stress intensity for stress corrosion cracking in 3.5 wt pct NaCl solution. AboveK _scelectroplated-zinc coatings do not appear to affect the crack-growth rate, although the incubation period prior to the onset of crack growth is reduced. Hot-dip zinc coatings increase stress corrosion crack growth rates slightly because of the additive effect of internal dissolved hydrogen. Hot-dip zinc coatings reduce the critical stress intensity for fracture in the absence of a corrosive environment because of embrittlement by internal hydrogen which is released from traps during hot-dip coating and confined by the inter metallic coatings which form on the steel surface in the hot dip bath. A simple fracture mechanics analysis indicates that either increasing diameter or the presence of a zinc coating lowers the critical hardness at which the stress corrosion cracking of structural bolts can occur.