Study on selective laser melting 316L stainless steel parts with superhydrophobic surface

An inverted trapezoidal structure was designed, and parts with such structure were fabricated with selective laser melting (SLM) technique. We comparatively studied the contact and sliding angles of water droplets of untreated, natural aging, heat treated and chemically modified parts, to characterize the superhydrophobic characteristics and analyze the wettability transition mechanism. We conducted the electrochemical corrosion test to analyze the anti-corrosion and corrosion resistance mechanism of the parts. We did wear test to study the wear performance of parts and analyze the wear mechanism. The experimental results show that the contact angles of water droplets of parts after aging treatment, heat treatment and chemical modification are 156 degrees, 155 degrees and 160.2 degrees, respectively, only the sliding angle of water droplets of chemical modification is 10 degrees, the rest are over 10 degrees, which implies that chemical composition of surface affects hydrophobicity of parts. Electrochemical corrosion tests show that micro texture can improve the material's anti-corrosion properties, and the chemically modified parts have strong corrosion resistance. Wear tests show that the micro texture can reduce the material's friction coefficient. At the load of 500 g, parts with chemical modification was observed superhydrophobicity disappearance after 40 min of wear. The friction coefficient of the chemically modified material is the smallest, 0.2228. After wear process, the surface is covered with fluoride and appears secondary structures. The wear methods are mainly abrasive wear and oxidative wear. The inverted trapezoidal structure has excellent superhydrophobicity, corrosion resistance and abrasion resistance by selective laser melting, providing a new method for manufacturing superhydrophobic parts.