I would recommend a preheat treatment of the metal surface before coating.. Then a post-heat treatment sometimes is necessarily after coating of the sample.
Thank you for your recommendation will try it. I treated the surface with multi-stage treatment. Also, I note that thickness plays a crucial part in line with heat treatment. The annealing time and temperature affect the coating; in the end, I tried three passes spry method with leaving samples hanged for ten minutes before starting annealing. so I got some non-cracked coated samples.