Hi ahmadsahid
Quote:1. How much the thickness per pass for Ni-base, Al-base, and Steel base?
Generally the metal based coatings are a bit more tolerant to being applied in thicker layers than ceramics and cermets. There are a few materials which seem to benefit from relatively thick coating per pass, particularly the exothermic bond coats and so called "one step coatings". NiAl bond coat is usual recommended to be applied to its final thickness (0.004 - 0.006" or 0.1 -0.15 mm) in just one single pass.
Heat transfer to the component being sprayed is significantly greater from material deposition than from the flame or heated gas stream. So the coating deposition rate/thickness per pass is a major consideration for controlling heat/temperature distribution in coating and substrate. So as general rule of thumb go for the minimum thickness per pass (high rotation and traverse speeds) practical for your set-up.
First look to see if there is any advice/guidance in the technical data sheets for application rates/speeds and feeds for specific the product. There are a few that like that extra heat abuse from heavy build ups per pass
Quote:2. How do you calculate traverse distance per revolution?
This depends on the width of your spray foot print which may vary depending on equipment/process/materials and parameters used. You want to set the traverse distance per revolution so that you get just enough overlap of coating to produce even coverage ie avoiding the point where you get a barber pole effect.