Coating Methods for Hydroxyapatite—A Bioceramic Material

Abstract

Hydroxyapatite (HAP), an apatite of calcium phosphate with the chemical formula (Ca 10 (PO4) 6(OH) 2) is one of the most valuable bioceramic materials with excellent bone-type composition. It is the best-suited material for orthopedic artificial human implants. Due to its high level of feasible characteristics like biocompatibility, osteointegration, non-toxicity, cytocompatibility, high thermal stability, anti-fungal and antibacterial etc., it is being highly researched for optimized composition based on applications. HAP as a coating material on biomedical substrates is effective for material upgradation. Enhancement in the surface morphology and characteristics of advanced biocomposite materials can be accomplished using a coating of HAP with different commercial methods including sol–gel, dip coating, spin coating, thermal spray, pulsed deposition, sputter, electrophoretic deposition, thermal, biomimetic, microarc oxidation and the combination of two or more coating methods. Various thin film deposition techniques like solution-based deposition technique, vapors-based deposition technique (VDT) and physical vapors deposition techniques are employed as and when desired based on applications and requirements. Further, Solution-based deposition techniques includes sol–gel coating, spin coating, dip coating, screen coating and combined coating technique. Vapor-based deposition technique includes metal–organic, low-pressure, atmospheric pressure and plasma-enhanced VDT. Physical vapor deposition techniques include thermal evaporation, pulsed laser deposition, molecular beam and sputtering deposition. The current chapter outlines various coating methods used for coating hydroxyapatite material on polymer, ceramic, metallic, non-metallic, alloy and composite material substrates. Also, applications of HAP and its coating in the biomedical field are briefly discussed. © 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.