热浸镀锌助镀剂及其助镀工艺的研究进展

综述了近年来热浸镀锌助镀剂及其助镀工艺的发展现状,给出了热浸镀锌常用助镀剂及其选择标准和作用机理,分析了助镀剂浓度、温度、铁盐含量和pH值等因素对热浸镀效果的影响,介绍了热浸镀中Zn-Al合金助镀剂、无铵助镀剂和电解活化助镀剂等新型助镀剂及其助镀工艺,指出了热浸镀助镀技术存在的问题和未来的发展方向。     

热浸镀锌性能及质量要求

根据镀锌层的防腐蚀作用及国家标准中对热镀锌层质量的规定,参照美、英、日等国及ＩＳＯ热镀锌标准中的有关规定和说明,对热镀锌层的质量要求问题进行了探讨。     

彩色热浸镀锌的研究

系统研究了彩色热镀锌工艺和耐蚀性能，通过镀液成分和工艺试验，筛选出Ｚｎ－Ｍｎ－Ｃｕ和Ｚｎ－Ｔｉ－Ｎｉ两种成分镀液，在一定的浸镀 冷却方式下，可以获得表面光滑、色泽均匀的彩虹、金黄、紫、蓝等彩色镀层。盐雾腐蚀试验表明，彩色热镀锌层比常规热镀锌层的耐蚀性能约提高一倍。通过俄歇能谱检验及理论分析，认为Ｚｎ－Ｔｉ－ＮＩ热镀锌镀层表面产生颜色是由于氧化膜使光发生了干涉，表面颜色决定于氧化膜厚度；Ｚｎ－Ｍｎ－     

热浸镀锌合金的研究现状以及发展趋势

热浸镀锌液中添加合金元素,将对镀层厚度、显微组织、耐蚀性和外观质量等产生重要的影响.本文重点介绍了含有Ni、Mg、Ti、Mn、Bi 5种合金镀层技术,探讨了这几种合金元素对热浸镀层组织、性能的影响,并展望了其发展趋势.     

钢基热浸镀锌铝合金的研究

为进一步提高镀锌层质量和耐腐蚀能力,通过在传统热浸镀锌中添加少量铝,获得了钢基热镀锌铝合金层。研究了钢基热浸镀锌铝合金镀过程中,助镀剂的组成,镀液温度、浸镀时间、钢基硅含量等因素对镀层厚度的影响,获得了一种耐腐蚀性好,结合力强和光滑的热镀锌铝合金层,该锌铝合金镀层与镀锌层相比,在二氧化硫气氛中的耐腐蚀能力有很大的提高。     

热浸镀锌铁损的研究

研究热镀锌过程中，助镀剂的组成，镀液和浸镀时间对钢铁基体损耗的影响。获得了一种对钢铁稳定、缓蚀的助镀剂及量佳镀锌和浸镀时间、大大提高钢铁基体热镀锌的质量，减少了损耗，提高了助镀和镀锌液的使用寿命。     

热浸镀锌合金镀层的研究进展

热浸镀锌液中添加合金元素,将对镀层厚度、显微组织、耐蚀性和外观质量等产生重要的影响.重点介绍了含有镍、镬、钛、锰、铋的5种合金镀层技术,探讨了这几种合金元素对热浸镀层组织、性能的影响,并展望了其前景.     

锌浴中Sb、Co、Ni对热浸镀锌合金层组织的影响

为了研究Q235钢热浸镀锌浴中Sb,Co,Ni元素的添加对合金镀层组织的影响,配制了 19种不同的锌浴对Q235钢进行3 min热浸镀.利用光学显微镜、扫描电镜、能谱仪等测试方法研究了锌浴中Sb,Co,Ni单组元的添加和多组元同时添加对合金镀层厚度的影响以及组织形貌的变化.结果表明:单独向锌浴添加Sb不能有效降低镀层厚...     

热浸Zn-Al合金镀层的研究进展

综述了近年来国内外对热浸Zn-Al合金镀层的研究,包括含Al量不同时镀层的组织与性能特点以及添加元素RE,Mg,Si的作用.介绍了Zn-5Al-RE、Zn-5Al-Mg、Zn-55%Al-1.6Si镀层和Zn-23%Al-Si镀层的组织结构、性能和防腐蚀机理及其应用场合以及Zn-Al合金镀层应用于批量热镀锌的研究与进展.     

热浸镀锌助镀工艺的研究与应用

热镀锌层质量及热镀锌过程中的锌耗成本与热镀锌的助镀工艺密切相关.通过对热镀锌助镀工艺的研究,阐述了热镀锌助镀作用机理,给出了钢铁制件热镀锌时助镀液的有效成分范围及工艺参数为:氯化锌铵200～400 g/L,铵锌比1.2～1.6,w(氯化亚铁)＜1%,pH值4～5,温度60～80 ℃,并分析了助镀液浓度、成分配比、铁盐含量、pH值和温度等因素对热镀锌的影响.结果表明,要获得良好镀锌质量及较低的生产成本,必须对热镀锌助镀液成分及工艺条件进行严格控制.     

连续冷镀锌卷取塔形产生原因及防范措施

主要从设备和工艺方面分析了镀锌带钢卷取塔形产生的原因。通过调整皮带助卷器各导辊（主要是弧形辊）来保证皮带运行轨迹,从而保证带钢穿带时两侧张力均匀,避免形成塔形。卷取区设备维护等方面进行改进后,卷取塔形问题也有了很大改善。     

低碳钢热浸Zn-0.15%Ni合金镀层组织及第二相粒子

采用热浸Zn-Ni合金镀锌方法,在含0.03%-0.36%Si的低碳钢上获得Zn-Ni合金镀层,研究了镀浴中Ni含量和钢中Si含量对镀层中δ相和ζ相生长速率的影响,以及Zn-Ni合金镀层η相中的第二相粒子即Zn-Fe-Ni三元化合物Γ2相粒子的形成和长大过程,结果表明,在Zn-0.15%Ni镀浴中,含硅0.03%-0.215%钢镀层的ζ相明显受到抑制,δ相厚度略有增加,Γ2相粒子的形成和长大过程包括ζ相的溶解,Γ2相的形核和成比例吸收铁,镍而长大。     

Modelling of iron dissolution during hot dip galvanising of strip steel

Abstract

During hot dip galvanising, the metal strip passes into the zinc bath at a temperature of ~460°C. Iron from the strip dissolves into the bath during this operation, leading to problems such as dross formation and pickup. The model described in the present paper has been created in an attempt to quantify and understand the amount of iron dissolving from the strip as it passes through the zinc bath. This is a mathematical model based on well defined first principles of nucleation, growth and diffusion. The effect of process parameters on the amount of iron dissolving from the strip has been analysed, showing possible actions that may help to reduce the amount of dissolution.     

含硅钢表面因素对热浸镀锌反应活性的影响

综述了含硅钢材表面状态因素对热浸镀锌反应活性的影响,这些因素包括亚表面氧化、表面粗糙度、表面残余应力、表面晶粒位向及表面组织结构等.结果表明,对于热轧状态的含硅钢材,亚表面氧化和表面粗糙度对热浸镀锌有明显的影响.对于其它因素的影响,目前尚无统一看法.     

Metallurgical investigations into the genesis of bare spots,exfoliation, and matte coating appearance in hot dip galvanized steel sheets

Continuously processed hot dip galvanized steel sheets that exhibited bare spots, exfoliation/peel-off, and matte coating appearance were investigated to gain an insight into the genesis of such defects. Scanning electron microscopy coupled with energy-dispersive X-ray spectrometry (SEM/EDS) and electron probe microanalysis (EPMA) were employed in conjunction with analysis of the galvanizing bath. Analyses revealed a bath condition sensitive to surface cleanliness of the steel substrate and showed significant levels of carbonaceous residues and rolling debris on the annealed steel substrates. This improper steel surface condition has been attributed to excess oil carry-over on the cold rolled strip surface and poor burnoff in the annealing furnace.     

Corrosion behaviour of hot dip zinc and zinc-aluminium coatings on steel in seawater

A comparative investigation of hot dip Zn-25Al alloy, Zn-55Al-Si and Zn coatings on steel was performed with attention to their corrosion performance in seawater. The results of 2-year exposure testing of these at Zhoushan test site are reported here. In tidal and immersion environments, Zn-25Al alloy coating is several times more durable than zinc coating of double thickness. At long exposure times, corrosion rate for the Zn-25Al alloy coating remains indistinguishable from that for the Zn-55Al-Si coating of similar thickness in tidal zone, and is two to three times lower than the latter in immersion zone. The decrease in tensile strength suggested that galvanized and Zn-55Al-Si coated steel suffer intense pitting corrosion in immersion zone. The electrochemical tests showed that all these coatings provide cathodic protection to the substrate metal; the galvanic potentials are equal to −1,050, −1,025 and −880 mV (SCE) for zinc, Zn-25Al alloy and Zn-55Al-Si coating, respectively, which are adequate to keep the steel inside the immunity region. It is believed that the superior performance of the Zn-25Al alloy coating is due to its optimal combination of the uniform corrosion resistance and pitting corrosion resistance. The inferior corrosion performance by comparison of the Zn coating mainly results from its larger dissolution rate, while the failure of the Zn-55Al-Si coating is probably related to its higher susceptibility to pitting corrosion in seawater.     

Fine structures in Fe3Al alloy layer of a new hot dip aluminized steel

The fine structure in the Fe-Al alloy layer of a new hot dip aluminized steel (HDA) was examined by means of X-ray diffractometry (XRD), electron diffraction technique, etc. The test results indicated that the Fe-Al alloy layer of the new aluminized steel mainly composed of Fe₃Al, FeAl and α-Fe (Al) solid solution. There was no brittle phase containing higher aluminum content, such as FeAl₃ (59.18% Al) and Fe2Al7 (62–93% Al). The tiny cracks and embrittlement, formerly caused by these brittle phases in the conventional aluminum-coated steel, were effectively eliminated. There was no microscopic defect (such as tiny cracks, pores or loose layer) in the coating. This is favourable to resist high temperature oxidation and corrosion of the aluminized steel.     

活性钢热浸锌镍合金镀层工艺与性能

热浸锌镍合金镀层技术是解决活性钢热镀锌问题的有效方法。分析了在常规热镀锌浴中加镍后,镍在镀层形成过程中的作用,以及对镀层工艺、性能的影响。结果表明,热浸锌镍合金镀层具有良好的粘附性能和耐腐蚀性能,表面光亮、均匀,减少了超厚现象,硬度和耐磨性有所提高。     

热镀锌中圣德林效应微观机理的解释模型

钢中Si含量对热镀锌反应的影响即圣德林(Sandelin)效应的微观机理尚无较完整而统一的解释.为此,汇集了主要的3种模型,即:Г失稳模型,J.Foct模型和析氢模型.Г失稳模型把含Si钢镀层的异常生长与相的失稳联系,认为Г相的失稳为Si提供了载体,Si进入ζ层中造成ζ层失稳而导致异常须状组织形成.J.Foct模型认为,含Si钢出现异常组织是由于浸锌时钢基体表面存在含饱和Si的液态锌层.析氢模型认为,钢中的Si不是直接影响热镀锌过程的,而是通过影响氢在钢中的扩散而间接影响热镀锌过程的.从效果方面看,这3种模型都能部分解释Sendelin效应的一些现象.最后对3种模型的优缺点进行了分析、归纳.