Mechanical Properties of Strontium–Hardystonite–Gahnite Coating Formed by Atmospheric Plasma Spray

In this work, we measured the mechanical properties and tested the cell viability of a bioceramic coating, strontium–hardystonite–gahnite (Sr–HT–G, Sr–Ca2ZnSi2O7–ZnAl2O4), to evaluate potential use of this novel bioceramic for bone regeneration applications. The evaluation of Sr–HT–G coatings deposited via atmospheric plasma spray (APS) onto Ti–6Al–4V substrates have been contrasted to the properties of the well-known commercial standard coating of hydroxyapatite (HAp: Ca10(PO4)6(OH)2). The Sr–HT–G coating exhibited uniform distribution of hardness and elastic moduli across its cross-section; whereas the HAp coating presented large statistical variations of these distributions. The Sr–HT–G coating also revealed higher results of microhardness, nanohardness and elastic moduli than those shown for the HAp coating. The nanoscratch tests for the Sr–HT–G coating presented a low volume of material removal without high plastic deformation, while the HAp coating revealed ploughing behaviour with a large pileup of materials and plastic deformation along the scratch direction. Furthermore, nanoscanning wear tests indicated that Sr–HT–G had a lower wear volume than the HAp coating. The Sr–HT–G coating had slightly higher cell attachment density and spreading area compared to the HAp coating indicating that both coatings have good biocompatibility for bone marrow mesenchymal stem cells (BMSCs).