SiO2溶胶和Al(H2PO4)3封孔处理对等离子喷涂Fe基合金涂层性能的影响

为降低热喷涂涂层孔隙率,提高涂层耐蚀性,分别采用SiO_2溶胶和Al(H_2PO_4)_3对等离子喷涂层Fe基合金涂层进行封孔处理。采用扫描电镜对比考察了封孔处理前后涂层微观形貌的变化,利用能谱仪分析了封孔处理后涂层内部封孔剂的分布状态,用X射线应力测定仪测试了涂层封孔前后残余应力的变化,使用电化学工作站获得了封孔处理前后涂层的极化曲线并对比考察了涂层的耐蚀性。结果表明,SiO_2溶胶和Al(H_2PO_4)_3均可在Fe基合金涂层表面形成一层封闭膜层,并通过毛细作用以涂层孔隙为通道进入涂层内部,从而显著降低孔隙,对涂层起到密封作用,并改善涂层致密性。经SiO_2溶胶和Al(H_2PO_4)_3封孔处理后,涂层表层拉应力由291 MPa分别降到45 MPa和105 MPa,自腐蚀电流密度分别降低2.9%和72.3%。

Effect of SiO2 Sol and Al(H2PO4)3 Sealed Treatment on Property of Plasma Sprayed Fe-based Coatings

SiO₂ sol and Al(H₂PO₄)₃ were used separately to seal the plasma-sprayed Fe-based coatings, in order to reduce porosity of thermal spray coatings and improve the corrosion resisting property of coatings. The morphologies of sealed coatings were observed by scanning electron microscopy (SEM), distribution of sealant inside sealed coatings was analysed by energy-dispersive spectrometry (EDS), the residual stress of sealed coatings was characterized by X-ray residual stress meter, and polarization curves of sealed coatings were made by electrochemical workstation to compare their corrosion resisting property. The results claim that both sealents could form dense film on coatings, and flow into the coatings through pores which acts as a channel under capillary force, reducing the porosity and improving the compactness of the coatings.The tensile stress of SiO₂ and Al(H₂PO₄)₃ sealed coa-tings reduce from 291 MP to 45 MPa and 105 MPa separately, and the corrosions current density reduced by 2.9% and 72.3% separately.