Tribocorrosion and corrosion behavior of AISI 4140 steel with ceramic Al2O3 coating developed by sandblasting

This study investigates the effects of varying sandblasting pressures on the adhesion, corrosion, and tribocorrosion resistance of Al2O3 films deposited on AISI 4140 steel via Physical Vapor Deposition (PVD). Sandblasting at pressures of 4, 6, and 8 bars was applied prior to Al2O3 coating to enhance the surface properties of the steel. Results indicated that increasing sandblasting pressure led to enhanced adhesion strength, with critical load (Lc) values rising from 18 N (untreated) to 25 N (8-bar sandblasted). However, corrosion resistance initially decreased due to increased surface roughness and microcrack formation from sandblasting, as shown by Ecorr values. Subsequent Al2O3 coating improved corrosion resistance, attributed to the protective oxide layer. Tribocorrosion tests revealed that Al2O3 coated samples exhibited lower wear rates and coefficients of friction, especially for the 8-bar sandblasted sample, due to enhanced surface hardness and reduced friction. This study demonstrates that the combination of sandblasting and Al2O3 PVD coating significantly improves adhesion, corrosion resistance, and tribocorrosion performance, with optimal results at an 8-bar sandblasting pressure. These findings underscore the effectiveness of this surface treatment for enhancing the durability of AISI 4140 steel in high-stress, corrosive environments. © 2025