A chrome carbide applied by an hvof process would probably work. The coating is about 98% porosity free if applied correctly and will not allow an attack on the base material.
I'm not sure of the conditions. The application is oil-well drilling. The customer has most of his tools chrome plated, but for the sour wells the calcium chloride eats them away. It's an inner surface of a narrow bore tube that needs to be coated, so HVOF is out. We're looking to use a unique inner diameter coating process, but need to determine the best material to deposit.
