Plasma sprayed alumina coatings on the surface of metals change greatly the corrosion law of metals in strong acid solutions and enhance effectively their corrosion resistance property. In this study, the plasma spray process was employed on substrate of AISI 304 stainless steel with deposition of AL2O3 ceramic coatings with and without Ni- 5%AL as bond layer. In order to enhance the corrosion resistance, a post-treatment has been carried out using polyester sealant. The porosity of the coating was measured by optical methods before and after sealing. The effectiveness of the type of coatings, bond layer, and sealing treatment on the corrosion behavior of the coatings were determined through static immersion test in 5%HCL. High corrosion resistance was obtained in the sealed condition where minimum porosity was occurred.