摘要
采用超音速火焰喷涂(HVAF)技术制备1.36%高孔隙率(high porosity,HP)和0.86%低孔隙率(low porosity,LP)两种铝基非晶合金涂层,研究孔隙率对铝基非晶合金涂层腐蚀行为的影响.通过扫描电子显微镜(SEM),X射线衍射仪(XRD)并结合3D高分辨X射线衍射形貌(3D XRT)分析涂层孔隙率以及微观组织结构,利用电化学测试系统和接触角测量仪研究涂层的腐蚀行为,采用X射线光电子谱(XPS)分析两种涂层钝化膜成分.结果表明:LP涂层的自腐蚀电流密度(Icorr)为3.0×10-6 A/cm2,点蚀电位(Epit)为-0.40 V,而HP涂层的Icorr为6.0×10-6 A/cm2,Epit为-0.47 V,LP涂层具有更好的耐局部点蚀能力;LP涂层的电荷转移电阻(Rct)约为HP涂层的2倍;LP涂层具有更大的接触角,疏水性更好;LP涂层形成的钝化膜中RE2O3的含量大于HP涂层,进一步说明LP涂层具有更优异的耐蚀性.
Abstract
High-velocity air-fuel spray(HVAF)technology was used to prepare two kinds of Al-based amorphous alloy coatings with high porosity(HP)of 1.36%and low porosity(LP)of 0.86%.The effects of porosities on the corrosion behavior of Al-based amorphous alloy coatings were studied.The porosities and microstructures of the coatings were analyzed by scanning electron microscope(SEM)and X-ray diffraction(XRD)combined with three-dimensional X-ray tomography(3D XRT).The corrosion properties of the coatings were studied by electrochemical testing system and contact angle measuring instrument.The passive film components of the two coatings were analyzed by X-ray photoelectron spectroscopy(XPS).The results show that the self-corrosion current density(Icorr)and pitting potential(Epit)of the LP coatings are 3.0×10-6 A/cm2 and-0.40 V,respectively.The Icorr and Epit for HP coatings are 6.0×10-6 A/cm2 and-0.47 V,respectively,signifying that the LP coating has better resistance to the localized corrosion;the charge transfer resistance(Rct)of LP coatings is about twice than that of HP coating;the LP coating has a larger contact angle,which proves that LP coating has better hydrophobicity and stronger corrosion resistance;the contents of RE2O3 in the passive film formed on the LP coating are larger,which further indicates that LP coating has better corrosion resistance.
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