Hi Arturas
Bond coat thickness ~ 0.1 - 0.15 mm (0.004-0.006") for optimum bond. 13Cr steel top coats are normally low shrink, low stressed, high thickness capable coatings - so little point building up bond coat as a thick buffer layer. In fact 13Cr steel is often used as an intermediate buffer layer (extension layer) for more highly stress coatings like austenitic stainless steel 316 type coatings and others that have limited thickness capability.
Quote:Also You wrote that sealing must be done for 13Cr coating. Coating porosity will secure oil in pores and sealing..... why we should do it?
I did not say "must be done". In some applications like crankshaft journals sealing is said to be important for maintaining oil film pressure and reducing hydraulic jacking stresses within the coating. In other less stressed conditions I would tend to agree that not sealing may be beneficial.