Analysis of the effect of MTMS-based silica powder as top coat on multi-layer coating on hydrophobicity of steel

A hydrophobic silica layer on the steel surface has been successfully fabricated. This layer with modified silica aims to determine the effect of silica powder as a filler in the topcoat in increasing the hydrophobicity of steel. Silica was obtained from the synthesis of methyltrimethoxysilane (MTMS) precursor using the sol-gel method. Silica was mixed with steel marine paint and coated as a topcoat on the steel surface. Coating paint on steel used a multi-layer coating with a spray coating method. The topcoat layer was varied with silica concentrations of 0 wt.%, 3 wt.%, 6 wt.%, 9 wt.%, and 12 wt.%. The characterization of the layers was done using WCA (Water Contact Angle) and AFM (Atomic Force Microscope). The characterization results revealed that the addition of MTMS-based silica concentration on the topcoat increased surface roughness and water contact angle to become hydrophobic. Layers with a silica concentration of 12 wt.% had the highest water contact angle values of 102˚ by fresh water and 104˚ by seawater.