【作者】 车淳山；

【导师】 卢锦堂；

【作者基本信息】 华南理工大学 ， 材料物理与化学， 2005， 博士

【摘要】 钢中的硅对常规热浸镀锌层的作用(即Sandelin效应)严重影响着镀锌层的质量,成为热镀锌行业亟待解决的难题。一定含硅量的钢(通常在0.1%Si附近和0.3%Si以上,这类钢在热镀锌行业通常被称为活性钢)在热镀锌时铁锌反应剧烈,生成超厚、表面灰暗且粘附力差的镀层,并导致锌耗增加。目前,对Sandelin效应还没有统一而令人信服的解释,现有的新技术如Technigalva(热浸锌镍合金镀层技术)等仍不能解决含硅量大于0.25%钢镀锌层过厚生长问题。为了解决这一长期困扰热镀锌行业的难题,本文研究了钢中的硅对热镀锌层生长的影响机理,探讨了解决活性钢(特别是Si%>0.25%)镀层过厚生长的新方法。本文炼制了五种典型含硅量的钢(0.04%、0.09%、0.14%、0.28%和0.36%Si),通过一系列的热浸镀锌试验,利用金相显微镜、扫描电镜及电子探针成分分析等测试技术,对五种钢在450℃不同条件下热浸镀锌层的生长动力学及组织变化进行了系统研究,探讨了钢中的硅对热浸镀层组织的影响,提出了一个新的较完整解释Sandelin效应的理论模型,并解释了Sebisty现象的形成原因;在此基础上研究了三种有效抑制Sandelin效应的方法,即预镀铁法、预镀镍法和Zn-Sn-Ni合金浴法,并通过系统研究这三种方法对热镀锌镀层生长动力学的影响及镀层生长过程中的组织变化,分别提出了这三种方法抑制活性钢镀层快速生长的机理。主要取得了如下研究成果:对五种含硅钢在纯锌浴中热镀锌层生长动力学及组织研究表明:镀锌层的生长呈现出典型的Sandelin效应,且镀锌时间越长,Sandelin效应越明显;亚Sandelin钢和Sebisty钢的镀层组织连续而致密,Sandelin钢的镀层组织由稳定区和活性区组成,稳定区组织与亚Sandeiln钢类似,活性区组织由薄而连续的δ层和疏松的(ζ+η)构成,过Sandelin钢组织由薄而不连续的δ层和疏松的(ζ+η)构成;钢中的硅造成热浸镀锌层出现异常生长最明显的变化就是ζ相以疏松块状粒子的形式生长;钢中的硅对镀锌层中的Г相的影响不同,亚Sandelin钢和Sandelin钢镀锌层稳定区具有连续Г层,Sebisty钢镀锌层的Г层不连续,Sandelin钢活性区和过Sandelin钢镀锌层不存在Г层; Sebisty钢镀锌层保持连续致密的原因是具有较厚的δ层。对预镀铁含硅钢在纯锌浴中的热镀锌层生长动力学及组织研究表明:含硅钢在预电镀一定厚度(≤10μm)的铁层后再热镀锌时均可以得到符合要求的热浸镀锌层,镀层致密连续,表面光亮;预镀铁法延缓并减弱了硅对热镀层组织的影响,故能抑制活性钢热浸镀锌层的快速生长,且抑制效果随镀铁层厚度的增加而增强;更多还原

【Abstract】 The role of silicon in steels to common hot dip galvanized coating, known as Sandelin effect, brings a detrimental influence on the quality of the coating. This has been an oppressive and difficult problem to galvanizing industry. The presence of silicon at certain levels (in the vicinity of 0.1wt% and above 0.3wt%) in steels,known as reactive steels in galvanizing industry, can result in the rapid growth of the Fe-Zn alloy layer, producing a coating of excessive thickness, having gray appearance and poor adherenc. Up to now, there is still lack of uniform and convincing knowledge about Sandelin effect. The present technologies such as‘Technigalva’have only effect on the over-growing coating of the steel with less than 0.25%Si. For solving the proplem which has disturbed galvanizers for a long time, the influence of silicon in steels on galvanized coating was sysmetically studied and new solutions of restraining the quick growth of the coatings of high-silicon (especially over 0.25%Si) steels were discussed.In this thesis, five types of silcon-containing steels(0.04%, 0.09%, 0.14%, 0.28% and 0.36%Si) were especially smelted and the growth dynamics and microstructure of hot dip galvanized coatings of those steels under different circumstances at 450℃were studied systmetically by a series of galvanizing experiments and by various of testing methods such as OM, SEM, and EPMA; the effect of silicon on the galvanized coating was discussed; a new and relatively complete interpretation model about Sandelin effect was establised; the Sebisty phenomenon was interpreted. Based on the results above, three solutions to Sandelin effect were brought forward, which were the iron-electroplated method, the nickel-electroplated method and the Zn-Sn-Ni alloy bath method. By systmetically studing the growth dynamics and microstructure of the coatings obtained by the three solutions, their mechanism of inhibiting the abnormal coating of silicon-containing steels were proposed.The study on the hot dip galvanized coatings of the steels in pure zinc bath reveals that the growth of the coatings displays a typical Sandelin effect and the longer the immersion time is, the more distinct the Sandelin effect is. The galvanized coatings of hypo-Sandelin steel and Sebisty steel are continuous and compact. The coating of Sandelin steel consists of stable region and reactive region. The microstructure in stable region is similar to the one of the coating of hypo-Sandelin steel while the microstructure in reactive region is composed of thin and continuousδ更多还原