Effect of prior electro or electroless Ni plating layer in galvanizing and galvannealing behavior of high strength steel sheet
Effect of prior electro or electroless Ni plating layer in galvanizing and galvannealing behavior of high strength steel sheet
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DOI：
10.1016/j.surfcoat.2016.12.067
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发表时间：
2017-04
影响因子：
5.4
通讯作者：
M. Manna;M. Dutta
中科院分区：
文献类型：
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作者：
M. Manna;M. Dutta
高强度钢在镀锌和合金化过程中极易产生镀层斑点。有时，GA涂层可能导致比GI涂层差的机械性能，因为在涂层中形成不同的脆性（Zn-Fe）金属间相。在这项研究中，一个创新的前镍电镀，然后热浸镀锌和镀锌合金化工艺被认为是获得良好的合金涂层质量。在高强度钢板表面预镀镍，可显著提高锌液在钢板表面的附着力。使用SEM-EDS和XRD技术对所有涂层进行深度分析。当在没有任何先前金属涂层的HS钢基底上形成GI涂层时，证实了纯锌相的存在，而当在具有先前Ni涂层的HS钢表面上获得GI涂层时，证实了合金相的存在，直到涂层的某个深度。具有先前Ni电镀的GA涂层主要由所需的Ni5.225Zn41.8相组成。Ni层控制了Zn和Fe的互扩散，得到了理想的合金镀层。具有先前Ni镀层的GI涂层提供了更好的抗氯化物侵蚀性，并且GA涂层确保了比GI涂层性能的显著改善。采用电沉积工艺在镀Ni的钢基体上获得了最佳的GA镀层。相对于在钢基材上没有任何先前Ni镀覆的GA涂层，该GA涂层在抵抗侵蚀性氯化物侵蚀的性能方面显示出3-4倍的改进、最低的粉化和优异的磷化性。
Galvanization (GI) and galvannealing (GA) of high strength (HS) steel surface is very prone to develop uncoated spots in coating. Sometimes, GA coating may lead to inferior mechanical performance than GI coating as different brittle (Zn-Fe) intermetallic phases are formed in the coating. In this study an innovative prior Ni plating followed by hot dip galvanization and galvannealing process was thought of to obtain good quality of alloy coating. Adherence of molten zinc on the surface of high strength steel sheet improved significantly by prior Ni coating. SEM-EDS and XRD techniques were used for depth analysis of all coatings. The presence of pure zinc phase was confirmed almost entire depth of the coating when GI coating was formed on HS steel substrate without any prior metallic coating whereas the presence of alloy phase was confirmed up to some depth of the coating when GI coating was obtained on HS steel surface with prior Ni coating. The GA coatings with prior Ni plating primarily compose of the desirable Ni5.225Zn41.8phase. Interdiffusion of Zn and Fe is controlled by Ni layer to get desirable alloy coating. The GI coatings with prior Ni plating layer provides better resistance against chloride attack and GA coating ensured significance improvement in performance than GI coating. The best GA coating was formed on the steel substrate with prior Ni coating by electrodeposition process. This GA coating showed 3–4 times improvement in performance against aggressive chloride attack, lowest powdering and excellent phosphatability with respect to the GA coating on the steel substrate without any prior Ni plating.