Cailiao gongcheng (Jul 2024)
Effect of pore characteristics on corrosion behavior of Al-based amorphous alloy coatings
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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