This paper aims to evaluate the effect of bond coat oxidation on the coating life of three TBC systems graded, duplex, and triplex. It investigates the hot corrosion resistance of the TBC's over nickel base alloys namely inconel 617 and IN738. Thermal plasma spraying is a flexible and versatile powder consolidation method. Plasma spraying is used to deposit thermal barrier coatings (TBCs). TBC's often faces the problems of spallation and cracking in service, due to the mismatch of thermal expansion coefficient between YSZ and the nickel alloy bond coat. Hot corrosion is a potential problem in many industrial applications including gas turbines, fuel conversion and combustion units, fuel cells, incinerators, and oil refinery equipment. The TBC's were deposited over two Ni-base alloys, namely Inconel 617and IN 738 with vacuum plasma spraying machine, from plasma - technique AG, Switzerland. Paper includes a German-language abstract.