Al-Si 도금강의 Mg 및 Zn 함량 변화에 따른 부식 거동 조사
Corrosion Behavior of Al-Si Coatings with Different Mg and Zn Contents
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This study aimed to enhance the corrosion resistance of Al–10Si-based plated steel by incorporating Mg and Zn—elements known for their low corrosion potentials—into the plating layer. We analyzed the effects of varying the content of these elements on both the microstructure and corrosion behavior. Using a Central Composite Design method, we developed nine plating compositions that combined Zn (0, 7.5, 15 wt%) and Mg (0, 2.5, 5 wt%). We evaluated the electrochemical properties of the plating layers through potentiodynamic polarization tests in a 3.5 wt% NaCl aqueous solution and examined the microstructures before and after corrosion using optical microscopy and SEM-EDS. The results of the potentiodynamic polarization tests revealed corrosion potentials ranging from -0.93 V to -0.56 V. Corrosion rates increased with Mg content, ranging from 2.36 × 10-6 A/cm to 2.9 × 10-5 A/cm . Statistical analysis indicated that Zn content primarily influenced corrosion potential, while Mg content affected the corrosion rate. Cross-sectional observations post-corrosion testing confirmed micro-galvanic corrosion behavior, characterized by the selective dissolution of eutectic Al-Si phases surrounding Si-rich phases within the plating layer.
Abstract
This study aimed to enhance the corrosion resistance of Al–10Si-based plated steel by incorporating Mg and Zn—elements known for their low corrosion potentials—into the plating layer. We analyzed the effects of varying the content of these elements on both the microstructure and corrosion behavior. Using a Central Composite Design method, we developed nine plating compositions that combined Zn (0, 7.5, 15 wt%) and Mg (0, 2.5, 5 wt%). We evaluated the electrochemical properties of the plating layers through potentiodynamic polarization tests in a 3.5 wt% NaCl aqueous solution and examined the microstructures before and after corrosion using optical microscopy and SEM-EDS. The results of the potentiodynamic polarization tests revealed corrosion potentials ranging from -0.93 V to -0.56 V. Corrosion rates increased with Mg content, ranging from 2.36 × 10-6 A/cm to 2.9 × 10-5 A/cm . Statistical analysis indicated that Zn content primarily influenced corrosion potential, while Mg content affected the corrosion rate. Cross-sectional observations post-corrosion testing confirmed micro-galvanic corrosion behavior, characterized by the selective dissolution of eutectic Al-Si phases surrounding Si-rich phases within the plating layer.