Effect of Sintering Temperatures on Mechanical and Electrochemical Properties of Sol- Gel Alumina Coatings Applied on Carbon Steel

Abstract In this research alumina sol-gel coating was applied on St44 steel by dipping, that sintered at temperatures of 300, 400 and 500?? after drying. Phase and micro structure analysis, corrosion resistance, adhesive strength and wear resistance were evaluated by XRD, SEM, electrochemical tests in 3.5% NaCl solution, pull off test and wear tester respectively. The results of DTA and XRD indicate that coating structure was amorphous at sintering temperature of 300?? and transformed to ?-Al2O3 completely at 500?? and transformed to ?-Al2O3 completely up to 1200??. Microscopic observation indicate minimum defects and maximum compaction for interface of sample sintered at 400??. The best wear and corrosion resistance obtained at 400?? and the decrease properties of sample sintered at 500?? could be due to cracks and holes caused by the phase transformation from amorphous to crystalline structure.