组分调制Ni/Cr多层膜合金化制备Ni-Cr合金覆盖层的耐腐蚀特性

Corrosion Performance of Ni-Cr Alloy Coatings Prepared by Alloying Ni/Cr Multilayered Films of Thickness Modulation

利用双槽电沉积法制备组分调制Ni/Cr多层膜,探讨了Ni/Cr多层膜的合金化特性。借助SEM和EDS对Ni-Cr合金覆盖层的表面形貌、微观结构以及化学组成进行了表征。结果表明,减小周期厚度,提高热处理温度,延长保温时间有助于提高多层膜的合金化程度。经高温处理后,Ni-Cr合金覆盖层化学组分均一,与理论值基本吻合;其微观形貌由原来的结节状或颗粒状结构转变为块状结构,并且未产生热应力开裂等现象。与相同厚度的镍镀层和铬镀层比较,Ni-Cr合金覆盖层具有更好的耐腐蚀性能。

Ni-Cr alloy coatings were prepared via a two-step process,namely Ni/Cr multilayered films of thickness modulation were firstly prepared by dual bath technique,which then subjected to alloying treatment at proper elevated temperature.The microstructure and chemical composition of Ni-Cr alloy coatings were characterized by means of SEM and EDS.The results show that with the decreasing period of modulation as well as the increasing heat-treatment temperature and time,the alloying process for Ni/Cr multilayered films could be expediently realized.After high temperature treatment,the chemical composition of the Ni-Cr alloy coatings is homogeneous on average,which is basically consistent with the theoretical value.Of which the surface morphology changes from the original nodular-or granular-like structure to block-like structure,while no thermal stress cracking is observed.Besides,their corrosion resistance was evaluated in comparison with nickel coating and chromium coating of the same thickness.It is found that the Ni-Cr alloy coatings have better corrosion resistance.