初始沉积行为对ZK60和ME20镁合金化学镀Ni-P镀层性能的影响

Effect of initial deposition behavior on properties of electroless Ni-P coating on ZK60 and ME20 magnesium alloys

镁合金材料组分与化学镀Ni-P合金镀层初始沉积行为密切相关。研究ZK60和ME20镁合金化学镀Ni-P镀层的初始沉积行为。研究结果显示,镁合金组分差异显著影响镀层初始沉积过程以及镀层的结合强度、耐蚀性能和晶体结构。镀层初始沉积均优先发生在两种镁合金基体表面沉淀颗粒上。而ZK60镁合金沉淀颗粒经HF活化后具有更高的化学活性,控制镀层的初始沉积速率。ME20镁合金的初始沉积速率与基体表面Mg F2膜层的致密性有关,而非沉淀颗粒。由于初始沉积行为的差异,ZK60镁合金镀层较ME20镁合金镀层具有更高的结合强度和更好的耐蚀性能。ZK60和ME20镁合金表面镀层主要是晶体结构,且ME20镁合金镀层中混有少量的微晶结构。

The composition of magnesium alloys is greatly associated with initial deposition behavior of electroless Ni-P coatings.Thus,the initial deposition behavior of electroless Ni–P coatings on ZK60 and ME20 alloys was investigated.The results indicated that differences in the alloy compositions significantly influenced the initial deposition process and the adhesive strength,corrosion resistance,and crystal structure.The initial deposition of coatings on ZK60 and ME20 alloys preferentially occurred on the precipitates.The precipitates in ZK60 alloy had higher chemical activity after HF activation and controlled the initial deposition rate of the coating.The initial deposition rate of the coating on ME20 alloy mainly depended on the density of the Mg F2 film formed by HF activation rather than on the precipitates.Owing to differences in the initial deposition process,the coating on ZK60 alloy had higher adhesive strength and better corrosion resistance than that on ME20 alloy.The coatings on ZK60 and ME20 alloys mainly had crystalline structures,and the coating on ME20 alloy had also a slight microcrystalline structure.