| Summary: | 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.
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