On the deposition of cold-sprayed hydroxyapatite coatings

Cold spraying is a well-established coating fabrication method for metals onto metallic substrates. Over the past decade, there has been a growing interest in its application as a deposition technique for hydroxyapatite (HAp) coatings due to its lower processing temperatures compared to conventional coating manufacturing techniques. HAp coatings are ceramic coatings employed in biomedicine for their biocompatibility and osteoconductive properties. The deposition of ceramic coatings using cold spraying remains a challenge due to the brittle nature of these materials when subjected to high-velocity solid-state impacts. In the present study, HAp deposits were produced via low-pressure cold spraying onto 316 stainless steel under various processing conditions to induce different energy states upon impact and elicit distinct responses in the deposited material. The morphology of the deposited HAp particles was examined after single-track experiments to comprehend the characteristics of the particles adhering to the substrate surface after each experiment. The study was supplemented with impact energy calculations, which allowed the establishment of processing windows to form HAp deposits and coatings. A cold-sprayed HAp coating was successfully obtained within the suggested range of experimental conditions based on energy calculations.