Effect of thermal treatment on mechanical and tribological properties of hybrid coatings deposited by sol–gel route on stainless steel

This paper deals with the effect of thermal treatment on the mechanical and tribological properties of an organic–inorganic hybrid coating deposited on stainless steel 430. Organic–inorganic coating derived from glycidoxypropyltrimethoxysilane (GPTMS) and aluminum tri-sec-butoxide Al(OsBu)3 were prepared via sol–gel route and deposited by dip-coating process with various thicknesses. A preliminary thermal analysis (DTA, TGA) of xerogel obtained by hydrolysis and condensation reaction of sols, highlighted three characteristic domains of temperature (110–200 °C, 250–300 °C, 400–500 °C). When thermal treatments were applied to the coated stainless steel in these temperature domains, the tribological behavior (wear and friction) underwent strong changes, analyzed from linear ball/plane tribometry. The tribological tests showed a lower friction coefficient and wear after thermal treatment at a temperature in the domain 250–300 °C. In order to explain this phenomenon, xerogel structure was studied from XRD and Raman spectroscopy and correlated to the mechanical and adhesive properties and to the tribological behavior.