Porous Stainless-Steel Coatings Produced by HVOF and Chemical Leaching

Abstract

Chemical leaching is proposed as a method to control porosity in stainless steel HVOF coatings. The leaching behavior is evaluated as a function of the stainless steel 444 and the pore former (Fe3Al) volume fractions and particle size distributions. The resulting porous structures are evaluated by optical microscopy. It was observed that the melting degree of the stainless steel splats was an important factor to retain some mechanical integrity after leaching. A discussion is presented to point out possible routes for the improvement of chemical leaching as a methodology for pore control in thermal spray coatings.