Chunshan CHE
,
Jintang LU
,
Gang KONG
,
Qiaoyu XU
金属学报(英文版)
doi:DOI: 10.1016/S1006-7191(08)60
In this article, five kinds of silicon-containing steel sheets have been electrodeposited, and then immersed in a pure molten zinc bath at 450℃ for various periods of time. The results by scanning electron microscopy (SEM) show that the coating of the sample (0.09 wt pct Si) with iron-electrodeposited pretreatment eliminates the reactive zones which are found in the coating without iron-electrodeposited pretreatment. The galvanized sample (0.28 wt pct Si) with iron-electrodeposited pretreatment exhibits a compact and coherent coating. The coating of the sample (0.37 wt pct Si) with the iron-electrodeposited pretreatment experiences a transition from a compact and coherent coating to a reactive one. The energy dispersive spectrum (EDS) results reveal that for the galvanized samples with iron-electrodeposited pretreatment, excessive silicon accumulates on the surface of the substrate due to the low solubility of silicon in the τ, after the iron layer is depleted by the increasing growth of the Fe-Zn intermetallics. With the movement of the substrate/τ interface toward the substrate, silicon-enriched α-Fe peels off from the substrate and breaks into the particles. The particles move toward the δ layer through the τ layer because silicon-enriched α-Fe cannot be absorbed in the τ layer. When the particles reach the δ/τ interface, they are dissolved in the δ layer, making the τlayer thin or even vanish.
关键词:
Zn coating
,
null
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null
,
null
,
null
C.S. Che
,
J.T. Lu
,
G. Kong
,
null
,
null
,
null
,
null
,
null
,
null
金属学报(英文版)
After steel sheets (0.37wt％Si) pre-electroplated with a thin layer of pure Fe were immersed in molten zinc for various time, the change in the microstructure of the galvanized coating on the steel and the change of α-Fe/ Γ interface were studied. The EDS (energy dispersive sepectroscopy) results show that excessive silicon accumulates on the surface of the steel substrate due to the low solubility of silicon in the Γ layer after the Fe layer is depleted by the increasing growth of the compound layers. With the movement of α-Fe/ Γ interface towards the substrate by the Fe/ Zn reaction, silicon-rich α-Fe peels off from the substrate and breaks into particles. The particles, much like an inert marker in a Kirkendall effect experiment, move towards the δ layer through the Γ layer because silicon-rich α-Fe can not be adsorbed in the Γ layer. On reaching the δ/ Γ interface, the particles quickly dissolve in the δ layer, and accelerate its growth, resulting in the gradual disappearance of the Γ layer. At the same time, the normal coating is quickly changed into coatings typical of reactive steels as silicon dissolved in the δ layer soon diffuses toward the ζ layer. A similar process may happen in the initial stage of galvanizing reactive steels on a small scale, although it is hard to be observed.
关键词:
Zn coating
,
钢
,
锌镀层
,
中间化合物
苑振涛
,
彭增华
,
王胜民
,
赵晓军
,
何明奕
材料保护
为了掌握机械镀锌中强化时间对镀锌层的影响,分别设置了4种机械镀锌的强化时间(0,5,15,60 min),制备了4种镀层.采用体视显微镜、表面洛氏硬度计研究了强化时间对锌镀层平整度、硬度的影响,采用重量法和铁试剂法分析了强化时间对锌镀层致密度和孔隙率的影响,采用XRD技术研究了强化时间对锌镀层物相组成的影响,采用中性盐雾试验研究了强化时间对锌镀层耐腐蚀性的影响.结果表明:在机械镀锌中随着强化时间的增加,锌镀层的平整度、致密度有所提高,硬度有所增加;强化时间对锌镀层的孔隙率、物相组成和耐蚀性没有影响.
关键词:
机械镀锌
,
强化时间
,
镀锌层
,
平整度
,
致密度
,
硬度
,
孔隙率
,
物相组成
,
耐蚀性
王友彬
,
曾建民
机械工程材料
采用热浸镀技术在Q235钢板表面制备了镀锌层,研究了浸镀时间对镀锌钢板拉伸性能的影响,通过扫描电镜观察了拉伸断裂后镀层表面、截面和断口处的形貌,分析了镀层的断裂机理.结果表明:与基体相比,Q235钢板热浸镀锌后的抗拉强度和塑性变形能力均下降;镀件抗拉强度的下降是由表面镀锌层强度低于基体的强度造成的;而塑性的下降则是由热浸镀时在基体表面形成的微裂纹造成的;由于残余应力的存在,微裂纹首先在σ-FeZn10层中形成,在受到拉应力时,裂纹沿晶界在σ-FeZn10层中向上扩展,然后在℃-FeZn13层中裂纹沿着FeZn13/Zn的相界面扩展,最后在η-Zn层沿晶界扩展直至镀层发生完全断裂.
关键词:
镀锌层
,
拉伸性能
,
断裂机理
