热喷涂技术制备耐液锌腐蚀涂层研究现状

介绍了热喷涂技术在制备耐锌液腐蚀涂层中的研究和发展状况,分析了热喷涂方法原理和特点,综述了主要的热喷涂工艺方法,展望了热喷涂技术制备耐液锌腐蚀涂层的应用和发展趋势。     

沉没辊基础件的熔融锌液腐蚀研究现状

根据近些年国内外耐锌腐蚀的研究成果,将耐锌腐蚀方法分为两大类:自身耐锌腐蚀材料和表面改性处理。自身耐锌腐蚀材料主要集中在Fe-Cr-Mn、Fe-B、Ti Al Nb等材料上,表面处理主要集中在WC-Co、Mo B-Co Cr、陶瓷等涂层上。两种方法都获得一定的研究成果,但也有一些不足。自身耐锌腐蚀材料的耐熔锌腐蚀虽有改善,但在液锌中也只是延缓了腐蚀速度,最终仍然会腐蚀失效。表面涂层耐蚀性相对较好,但是在锌液中仍然会发生裂纹腐蚀,并且涂层和基体之间的物理匹配性较差,脆性较大,工件的轻微碰撞很容易造成涂层的脱落,加速工件的腐蚀,不宜用于实际生产。充分利用陶瓷耐腐蚀、耐高温、硬度高的优点,以及金属室温强度好、延展性好的优点,开发陶瓷金属复合涂层,可能会成为下一步沉没辊基础件熔融锌液腐蚀研究的主要方向。     

耐液锌腐蚀涂层的研究现状

工业连续热浸镀锌生产线上,沉没辊、轴承等部件受到锌液的强烈腐蚀.耐液锌腐蚀涂层能够保护其免受液锌腐蚀的破坏.现有的耐液锌腐蚀涂层如金属涂层、金属陶瓷涂层、氧化物陶瓷涂层等耐液锌腐蚀寿命短、材质脆、易脱落,无法为部件提供有效保护.本文回顾了液锌对铁基合金的腐蚀机理,综述了耐液锌腐蚀涂层的研究现状.同时,文章指出了发展新型涂层材料和制备技术是未来耐液锌腐蚀涂层发展的一个必然趋势.     

热喷涂技术在锌锅部件中的应用

连续热镀锌生产线锌锅部件受到锌液腐蚀、磨蚀、锌渣粘附等影响,提高锌锅部件的使用寿命既能提高镀锌板产品质量,又能降低成本,提高效率.本文介绍了热喷涂技术在制备锌锅辊涂层、轴承/轴瓦涂层中的研究和发展状况,分析了各种热喷涂方法的技术和工艺要点,综述了锌锅部件涂层材料的发展过程,展望了热喷涂技术制备锌锅部件涂层的应用和发展趋势.     

304不锈钢/Ti-45Al-8Nb电火花沉积涂层在熔锌中的腐蚀行为

以304不锈钢为基材,Ti-45Al-8Nb金属间化合物为电极,制备电火花沉积涂层,并研究其在锌液中的腐蚀行为。结果表明,涂层与基体呈冶金结合,是电极材料与基体材料剧烈重熔扩散的产物。相比304不锈钢,涂层样品的耐熔锌腐蚀性能显著提升,表现为孕育型腐蚀,孕育期为15天。涂层的腐蚀最初发生于样品的棱角处,属于典型的裂纹-瓦解机制。涂层碎片与锌液发生少量元素扩散,生成富Fe、Al的腐蚀产物。依据润湿的相关理论,讨论了涂层中原生裂纹对涂层耐熔锌腐蚀性能的影响。如果适当改善沉积工艺,减少涂层裂纹,有望延长涂层的使用寿命。     

热喷涂WC-12Co涂层在锌液中腐蚀失效过程分析

为了分析热喷涂WC-12Co涂层对热镀锌沉没辊的保护效果,利用超音速火焰喷涂设备制备了WC-12Co涂层试件,并浸入460 ℃的熔融锌液中,分析腐蚀时间对涂层的影响. 通过SEM和X-Ray分析腐蚀后涂层的组织形貌和相组成. 结果表明,WC颗粒与锌液不润湿,不发生反应,钴与锌液反应生成脆性的化合物,导致涂层开裂-剥落失效. 涂层中原始孔隙并不会造成锌液的侵入,但随着腐蚀时间的增加,锌在涂层中扩散并与钴化合,导致了横向裂纹出现,造成涂层的失效.     

超音速火焰喷涂制备的WC-WCoB涂层在熔锌中的腐蚀行为及其耐蚀机理

目的揭示新型WC-WCoB涂层在锌液中的腐蚀行为及耐蚀机理,从而提高WC基涂层的耐熔锌腐蚀性能。方法以WC、Co和WB粉末为原料,结合离心喷雾干燥和真空热处理,制备得到具有高球形度、结构致密的WC-WCoB热喷涂粉末喂料,并利用超音速火焰喷涂工艺进行涂层的制备。将涂层浸泡于熔融锌液中不同时间,观察其截面组织,以评价涂层的耐熔锌腐蚀性能,并通过X射线衍射仪、热重/差热分析仪、扫描电子显微镜、能谱分析仪对涂层进行结构、性能表征。结果 WCoB相与熔锌间不发生化学反应,制备的WC-WCoB涂层在锌液中浸泡达600 h时,仍未观察到Zn向涂层内的扩散,但在锌液中氧的缓慢作用下,涂层边缘处易产生微裂纹并逐步向内扩展,最终导致涂层材料逐层剥落。WC-WCo B涂层在腐蚀600 h后,完好区域面积占试验涂层总面积的56.3%。结论在传统WC-Co涂层中添加一定量的WB,可使Co相完全转化为WCoB相,与目前广泛使用的WC-η涂层相比,该研究制备的WC-WCoB涂层具有更突出的抗氧化性能,使其在锌液中由于氧化引起的裂纹形成扩展速率显著降低,宏观上表现出更强的耐熔锌腐蚀性能。     

双涂层汽车钢板的耐蚀性研究

通过对冷轧含铌钛高强度汽车钢板进行超音速火焰喷涂单一涂层和双涂层,并进行了中性盐雾腐蚀和电化学腐蚀试验与对比分析。结果表明:热喷涂单质锌层后再热喷涂锌铝钇复合涂层的双涂层,使中性盐雾腐蚀240 h后的质量损失率较单质锌单一涂层减少10.98%,较锌铝钇单一涂层减少5.02%;使其在室温的6%NaCl电解液的腐蚀电位较单质锌单一涂层正移23.38%,较锌铝钇单一涂层正移15.02%,汽车钢板的耐蚀性得到显著提高。     

电弧喷涂锌涂层的酸雨腐蚀性能

热镀锌涂层因具有优越的耐腐蚀性、涂装性能等被广泛应用于工业生产众多领域,成为金属材料在户外工作环境下防腐蚀的有效措施之一。为研究热喷涂锌涂层在酸雨中的腐蚀行为,采用电弧喷涂技术在Q235碳素结构钢表面喷涂锌涂层,模拟酸雨腐蚀环境,在腐蚀液pH值改变的情况下,采用SEM,XRD,硬度测试及失重分析等手段,分析不同pH值溶液腐蚀后涂层的表面形貌和腐蚀产物,及试样的硬度变化和腐蚀速率情况。结果表明,锌涂层的表面腐蚀会随着模拟酸雨溶液pH值的降低而加重,其表面腐蚀产物逐渐增多,腐蚀产物的形貌由小块状逐渐变成羽针状和岛状,主要成分为Zn(OH)2,ZnSO4和Zn4SO4(OH)6·3H2O;涂层表面硬度最高为23.4 HV、最小腐蚀速率为0.21×10-4g/(m2·h),但当模拟酸雨溶液pH值由7降至2.8时,涂层表面硬度降低约12%,腐蚀速率约增大至最小值的26倍;模拟酸雨溶液pH值在5～2.8时,溶液对锌涂层的腐蚀比较严重。     

硅镇静钢热浸镀Zn－Ni合金

研究了硅镇静钢在Ｚｎ－０．０９％Ｎｉ合金镀液热镀后镀层的组织结构、耐盐雾腐蚀性能，并研究Ｚｎ－０．０９％Ｎｉ合金镀液对锌锅材料的腐蚀作用。结果表明，镀液中加入０．０９％Ｎｉ以后，镀层中的ζ相层减簿，晶粒细化，Ｎｉ富集在ζ相柱状晶的晶界上；Ｚｎ－Ｎｉ合金镀层的耐盐雾腐蚀寿命是纯锌镀层的２倍；Ｚｎ－Ｎｉ合金镀液能减缓对锌锅的腐蚀作用。     

The Structure and Protective Properties of Zinc and Nickel Alternate Electrodeposits

A NEW TYPE of coatings consisting of a large numberof laminar deposits has been the keen subject of muchresearch,because these layered-structure coatingspossess improved properties or novel phenomenon suchas increased mechanical strength,micro-hardness,giantmagnetoresistance and corrosion resistance[1"6'.Thesecoating systems with individual layers making upoverall structure are also called compositionallymodulated multilayer(CMM)coatings'3"5'.In view ofthe plating historical use of surface…     

Corrosion resistance of hot‐dipped zinc and zinc alloy coated sheet steels under offshore atmospheric environment

The application of hot‐dipped zinc and zinc‐aluminum alloy coatings were introduced. Exposure tests of the steels with these coatings were conducted in the offshore atmosphere in Qingdao and Xiamen for 12 years separately. Effects of the coating thickness, alloy composition and atmospheric environment on the corrosion performance were studied. Results of the onsite exposure tests were compared with the results of a previous indoor salt spray accelerated corrosion tests. The study supports that zinc‐aluminum alloy coatings are useful in providing better corrosion resistance and can be further developed for future applications.     

机械镀的镀层形貌及耐蚀性

分别用325、800目颗粒状锌粉或325目锌粉 10%铝粉球磨成的片状复合粉,在促进剂作用下,形成三种机械镀层。用SEM法测定了金属原料粉及镀层的SEM形貌;用盐雾试验测定了镀层的耐蚀性。试验结果表明:片状锌-铝复合粉形成的镀层综合性能优于800目粒状锌粉形成的镀层。另外,随着金属粉粒度的减小、铝粉的添加及片状化处理,使镀层的光亮度、密实度和耐腐蚀性明显提高。     

锌粉粒度对机械镀锌层耐腐蚀性能的影响

分别采用325目、800目和325目+800目等质量混合的球形锌粉,在活化剂的作用下进行机械镀锌,得到三种机械镀锌层。观察了三种镀锌层的表面形貌和断面结构,分析了不同粒径锌粉所得镀层的结构特点,通过中性盐雾试验测试了镀层的耐腐蚀性能。结果表明:325目锌粉镀层的耐腐蚀性能最差,800目锌粉镀层的耐腐蚀性能最好,325目与800目等质量混合的锌粉镀层耐腐蚀性能介于两者之间,接近800目锌粉镀层。     

磷化/硅酸盐溶胶封闭后处理复合膜的自愈机理(英文)

通过磷化/硅酸盐溶胶封闭后处理技术,在镀锌钢表面生成完整的复合膜。采用X射线光电子能谱研究复合膜的化学组成。将复合膜用刀片划伤至露出锌层,经中性盐雾(NSS)腐蚀若干时间后,采用SEM和EDS研究划痕表面腐蚀产物的显微组织和化学成分,并与未划伤的腐蚀试样进行对比。探讨复合膜的自愈机理。结果表明,在腐蚀过程中,复合膜溶解出的自愈性离子扩散迁移至划痕表面或缺陷处,与Zn2+重新结合生成不溶性化合物,覆盖划痕或缺陷表面。腐蚀产物中含有Si、P、O、Cl和Zn五种元素,为致密细小的针片状,能较好阻滞裸露锌层腐蚀的形成和扩展。复合膜具有良好的自愈性能。     

Enhanced corrosion protection by powder coatings on hot rolled steel (HRS) for high-temperature applications

Hot rolled steel (HRS) has long been a major product to the motor industry for bodywork, as galvanised steel (zinc coatings), and it is widely used in building and as tinplate (including tin and chrome oxide coatings) for food, etc. can-making. Among more specialist uses its moderate production costs makes it suitable for the manufacturing process. In this study, newly developed corrosion protection enhanced silicone based powder coating was evaluated on hot rolled steel (HRS). The powder coating in this study was developed to withstand high temperatures up to 550°C without any degradation. In the study silicone resin was incorporated with fillers, corrosion inhibitors and fibres at various compositions to achieve maximum heat resistance and improved corrosion resistance. Protective behaviours of the differently formulated powder paints were investigated before and after heat exposure. The developed paint system was evaluated using various test methods such as heat resistance, salt spray, Electrochemical Impedance Spectroscopy (EIS), adhesion test and microstructure study using SEM. The evaluation of test results revealed that powder coating combining zinc dust particles and mineral fibres have better performance due to better corrosion and adhesion stability in the corrosive environment before and after heat exposure up to 550°C.     

镀锌板在不同加速腐蚀环境下的腐蚀行为研究

目的研究中性盐雾环境、中性盐雾加周浸环境和中性盐雾加湿热环境下镀锌板的腐蚀行为,明确不同加速腐蚀试验环境对镀锌板腐蚀行为的影响。方法对镀锌板进行中性盐雾、中性盐雾加周浸、中性盐雾加湿热等不同类型的加速腐蚀试验,通过失重法、SEM、XRD以及极化曲线等方法,对比不同加速腐蚀试验类型对镀锌板腐蚀行为的影响。结果在三种加速腐蚀试验环境下,镀锌板的腐蚀过程基本相同:镀锌层及白色锌锈腐蚀、锌层破裂、锌层完全脱落、基体碳钢腐蚀。腐蚀产物都以Zn(OH)_2、γ-FeOOH、ZnO、Fe_2O_3等为主。三种环境下镀锌板的腐蚀都不均匀,不同位置的腐蚀情况存在一定差异。其中,中性盐雾环境下材料腐蚀情况最为严重,中性盐雾加周浸环境次之,中性盐雾加湿热环境下最轻。结论三种加速环境都是主要通过Cl~-在锌表面的沉降和溶解作用增强介质的导电性能,加剧锌层的腐蚀。在中性盐雾环境中,Cl~-浓度最高,试样腐蚀最严重。在中性盐雾加周浸环境中,SO_4~(2-)与Cl~-协同作用,腐蚀也较严重。而中性盐雾加湿热环境中,Cl~-被稀释,腐蚀情况最轻微。     

Fe/Cr涂层抗热腐蚀性能研究

设计制造出Fe/Cr粉芯丝材,利用电弧喷涂技术制备出耐高温腐蚀的工作涂层。运用光学显微镜、扫描电子显微镜(SEM)、X射线衍射仪(XRD)等研究了电弧喷涂Fe/Cr合金涂层的微观结构、腐蚀动力学和高温下的腐蚀性能。结果表明,该涂层组织致密,涂层中形成Cr2O3或尖晶石型氧化物是其具有优异的抗高温腐蚀性能的主要原因,涂层抗高温腐蚀性能较好。     

The Corrosion Behavior of Cold Sprayed Zinc Coatings on Mild Steel Substrate

Zinc and its alloy coatings have been used extensively for the cathodic protection of steel. Zinc coating corrodes in preference to the steel substrate due to its negative corrosion potential. Numerous studies have been conducted on the corrosion behavior of zinc and its alloy coatings deposited using several techniques viz., hot dip galvanizing, electrodeposition, metalizing or thermal spray etc. Cold spray is an emerging low temperature variant of thermal spray family which enables deposition of thick, dense, and pure coatings at a rapid rate with an added advantage of on-site coating of steel structures. In the present study, the corrosion characteristics of cold sprayed zinc coatings have been investigated for the first time. In addition, the influence of heat treatment of zinc coating at a temperature of 150 °C on its corrosion behavior has also been addressed.     

Effect of silicate pretreatment, post-sealing and additives on corrosion resistance of phosphated galvanized steel

Sodium silicate （water glass） pretreatment before phosphating, silicate post-sealing after phosphating and adding silicate to a traditional phosphating solution were respectively carried out to obtain the improved phosphate coatings with high corrosion resistance and coverage on hot-dip galvanized（HDG） steel. The corrosion resistance, morphology and chemical composition of the coatings were investigated using neutral salt spray（NSS） tests, scanning electron microscopy（SEM） and energy dispersive spectroscopy（EDS）. The results show that pretreatment HDG steel with silicate solutions, phosphate coatings with finer crystals and higher coverage are formed and the corrosion resistance is enhanced. Adding silicate to a traditional phosphating solution, the surface morphology of the coatings is nearly unchanged. The corrosion resistance of the coatings is mainly dependent on phosphating time. Phosphating for a longer time （such as 5 min）, the corrosion resistance, increasing with concentration of silicate, is improved significantly. Post-sealing the phosphated HDG steel with silicate solutions, the pores among the zinc phosphate crystals are sealed with the films containing Si, P, O and Zn and the continuous composite coatings are formed. The corrosion resistance of the composite coatings, related to the pH value, contents of hydrated gel of silica and Si2O^2- 5 and post-sealing time, is increased markedly. The improved coatings with optimal corrosion resistance are obtained for phosphating 5 min and post-sealing with 5 g/L silicate solution for 10 min.