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).