Co-Mn3O4复合镀层转化为（Co,Mn）3O4尖晶石涂层的研究

Research on Conversion from Co-Mn3O4 Composite Plating Coating to（ Co,Mn）3O4 Spinel Coating

为了制得满足铁素体不锈钢连接体实际需求的(Co,Mn)3O4尖晶石涂层,采用复合电镀法在E-brite表面涂覆Co-Mn3O4先导层,在空气中以5℃/min的速率升温至800℃进行氧化。用扫描电镜(SEM)分别观察热转化前后涂层的表面及截面形貌,用能谱(EDS)和X射线衍射仪(XRD)分析转化后涂层的元素分布及物相变化。结果表明:沉积10 min后得到厚度约8μm、弥散均匀且与基底结合良好的Co-Mn3O4复合镀层;氧化10 min后,形成内部为CoO、外部为Co3O4的双层氧化物且Mn3O4未与镀层基质完全融合;氧化60 min后,复合镀层完全转化为(Co,Mn)3O4尖晶石涂层;基底与涂层存在元素的互扩散现象,界面处形成致密的厚约2~3μm的Cr2O3氧化层,涂层能够有效阻隔Cr进一步向外挥发。

The Co-Mn3O4 precursor layer on ferritic stainless steel E-brite was prepared by electrolytic codeposition,and then the obtained plated samples were exposed at 800℃in air with a heating rate of 5℃/min for thermal conversion.The surface and cross-section morphologies of deposited layer were observed with scanning electron microscopy(SEM).Moreover,the element composition and phase change of converted coating were analyzed with energy-dispersive spectroscopy(EDS)and X-ray diffraction(XRD).Results showed that after electrolytic codeposition for 10 min,the Co-Mn3O4 composite layer with 8μm of thickness and uniform dispersed property were prepared and combined well with E-brite.After oxidation treatment for 10 min,the plated layer converted into a double-layer microstructure with an inner Co O layer and outer Co3O4 layer,while the Mn3O4 particles was not completely dissolved into the oxide layer.After oxidation treatment for 60 min,the surface layer was fully converted into the(Co,Mn)3O4 spinel coating.There was element inter-diffusion between coating and substrate,while a dense Cr2O3 oxide layer with a thickness of 2-3μm was formed at the interface,and the coating could block Cr volatilization outwards effectively.