Development of corrosion-resistance metal additively manufactured materials

• Main Author: Choo, Jing Yi
• Other Authors: Ho Jin Yao
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2024
• Subjects: Engineering; Corrosion
• Online Access: https://hdl.handle.net/10356/176433
• Institution: Nanyang Technological University

This final year project focuses on the investigation of the anti-corrosion performance of pristine additively manufactured (AM) aluminium alloy, AlSi10Mg, and the development of the surface coating to enhance its corrosion resistance. To enhance the corrosion resistance performance, the surface morphology of AlSi10Mg is modified by chemical etching, and its surface is coated with a low surface energy material to achieve superhydrophobicity. Such superhydrophobic surfaces (SHP) are known for their ‘highly non-wetting’ characteristics, enabled by the micro and nanostructures generated on the metal surfaces. To investigate the corrosion performance of different surface morphology of AlSi10Mg, a combination of different coating development methods was used. The microstructures are altered by varying heat treatment temperature and chemical etching duration to differ the depth of material removal to create microstructures. To obtain an SHP surface, a layer of Heptadecafluoro-1,1,2,2-Tetrahydrodecyl silane (HTMS) is selected as the low surface energy material coated on the surface. Some samples are coated with a layer of mineral oil to create slippery liquid-infused porous surfaces (SLIPSs). A total of 50 samples were prepared and investigated. Each surface underwent a series of corrosion tests to determine its anti-corrosion performance. The series of tests include Electrochemical Frequency Modulation (EFM), Linear Polarization Resistance (LPR), Electrochemical Impedance Spectroscopy (EIS), and Potentiodynamic Polarization (Tafel). Characterisation of the corrosion resistance performance of each surface was performed through a scanning electron microscope (SEM) to assess the changes in micro and nanostructures, water contact angle (WCA) analysis to determine the hydrophobicity, and surface roughness analysis. This study has shown that SLIP surfaces are generally more well-performing in corrosion resistance than SHP surfaces, especially for Al6061 and non heat-treated superhydrophobic AM surfaces. Among all the samples, the best anti corrosion surface is determined to be the AM HT 300 sample which undergoes chemical etching using 5M hydrochloric acid over one minute duration.