[Hydroxyapatite coating on metal plates using an aerosol jet printing system]

The purpose of the present study was to investigate the properties of the hydroxyapatite (HA) layer formed by an aerosol jet printing system, aimed at application to the field of dentistry. The HA particle was adhered to the metal substrate. The particles of HA were 1 micron or less in size and were packed closely. When the composition of the formed HA layer was compared to that of the raw material powder, oxygen was increased, but Ca was decreased. Moreover, Ca and P were almost evenly distributed in the layer, but oxygen was not. Dynamic hardness of HA coatings was 31.5 +/- 1.1. The peel strength of HA coating was the highest, at 58.7-39.6 MPa, in 10 microns layer thickness. Interface fractures were observed at 10 microns layer thickness, and cohesive fractures were observed for all other layer thicknesses. The wear amount of HA coating by tooth brush abrasion was significantly large at 100 degrees C heating (p < 0.05), compared with at 250 degrees C and 500 degrees C. At any substrate temperatures, the wear amount of stainless steel substrate tended to be smaller than that of titanium substrate.