A versatile thin polysiloxane composite coating targeting for threads endowed with properties of anti-corrosion and friction reduction

Threads play an essential role of connecting pipes, but they are still faced with an enormous challenge of corrosion and gluing. Herein, the thin polysiloxane composite coating filled with MoS2 modified by γ-(2, 3-epoxypropoxy) propytrimethoxysilane (MK) and nano-SiO2 was prepared. MK prolongs the corrosion path and possesses lubrication property while nano-SiO2 fills the micropores during the solvent evaporation and provides rolling friction simultaneously. The synergistic effect of MK and nano-SiO2 endows coatings with unique properties of anti-corrosion and friction reduction, catering for the demands of thread coatings. Specifically, electrochemical impedance spectroscopy (EIS) manifested that the impedance at 0.01 Hz of the optimal ~30-μm-thick coating still maintained at 3.16 × 1010 Ω·cm2 after the immersion in 3.5 wt% NaCl solution for 30 days. The average coefficient of friction (COF) of the final product was 0.2769, decreasing by 27.69 % compared with that of the pure 818C coating, which could lower the risk of thread gluing. The composite coating prepared in this work could become a potential candidate of protecting threads.