Fig. 4a and b shows the hardness behavior as function of the indentation relative depth for the two coating system thickness under investigation in this project. These plots were built by indenting the coating system with loads that ranged from 0.245 N (0.025 kg) to 0.49 N (0.5 kg). According to the hardness versus the reciprocal of the indentation diagonal plot, the indention size effect (ISE) at small loads is negligible. Because the hardness behaves linearly with the reciprocal of the indentation diagonal in which fitting parameter (R) is 0.9968 [16]. According to the up to date theory the hardness behavior