Formation and corrosion behavior of calcium phosphate coating layers on ZK60 alloy coated at various pH conditions by chemical conversion method
Formation and corrosion behavior of calcium phosphate coating layers on ZK60 alloy coated at various pH conditions by chemical conversion method
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DOI：
10.1016/j.surfcoat.2022.128639
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发表时间：
2022-06
影响因子：
5.4
通讯作者：
Le Thi Trang;Cao Quang Nguyen;S. Hiromoto;O. Minho;E. Kobayashi
中科院分区：
文献类型：
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作者：
Le Thi Trang;Cao Quang Nguyen;S. Hiromoto;O. Minho;E. Kobayashi
磷酸钙涂层的形成和防腐性能取决于涂层条件和镁(Mg)基材的类型。因此，本研究旨在研究在较宽的pH范围内(pH=6.5~10.2)，在镁-6质量%锌-0.5质量%锆(ZK60)合金表面形成的钙磷涂层。采用镁离子定量浸泡实验研究了不同类型的磷酸钙涂层对ZK60的降解行为。结果表明，钙磷涂层的形态和类型受pH条件的控制。在pH=6.5时，形成磷酸八钙(OCP)单相层。在pH=7.0时，形成了OCP+羟基磷灰石(HAP)混合层。在pH=7.8和10.2时，分别形成了HAP单层和带有中间层的HAP层。涂层具有良好的防腐性能，但防腐程度不同。PH为7.8的涂层具有最好的耐腐蚀性。在该标本上，生物相容的羟基磷灰石(HAP)在浸泡后作为腐蚀产物沉积。结果表明，pH值为7.8的涂层标本是一种合适的骨科植入物。
The formation and corrosion protectiveness of calcium phosphate coating layers depend on the coating conditions and the type of magnesium (Mg) substrate. Therefore, this study aimed to investigate the formation of the calcium phosphate coating layers on Mg-6mass% Zn-0.5mass%Zr (ZK60) alloy over a wide pH range of pH 6.5 to 10.2. Immersion tests with Mg2+ion quantification were performed to study the degradation behavior of ZK60 coated with different types of calcium phosphate. It was found that the morphology and types of the calcium phosphate coating layers were controlled by pH conditions. At pH 6.5, an octacalcium phosphate (OCP) single phase layer was formed. At pH 7.0, an OCP + hydroxyapatite (HAp) mixture layer was formed. A HAp single layer and a HAp layer with an intermediate Mg(OH)2layer were formed at pH 7.8 and 10.2, respectively. The coating layers provided good corrosion protection but at different levels. The specimen coated at pH 7.8 possessed the best corrosion resistance. On this specimen, biocompatible hydroxyapatite (HAp) was deposited as a corrosion product after the immersion. The results suggest that the specimen coated at pH 7.8 serves as a suitable orthopedic implant.