Enhanced Adhesion and Corrosion Properties of Boron Doped Bioceramic Coated 316L Implants

Abstract: In order to provide an effective prevention to 316L implants, a synthesized bioceramic was coated by using electrophoretic deposition (EPD). The effect of boron addition into hydroxyapatite (HA) on surface morphology, adhesion and corrosion resistance of the implant has been examined. Boron doped HA (B–HA) was synthesized by a simple chemical acid-base method with 5, 10, and 15 wt % boron additions to coat on 316L implants. The synthesized B-HA was coated on the substrates and the coated surfaces with and without B additions. Sintering took place at different temperatures and sintering rates. The coatings were characterized by X-ray diffractometer (XRD), Fourier transform infrared spectroscopy (FT–IR) and scanning electron microscope (SEM). Furthermore, adhesion and in vitro corrosion tests were conducted. The influence of boron additons on adhesion and corrosion resistance of 316L have been revealed for the coated substrates at different B additions. It was shown that boron addition increased the adhesion and corrosion resistance of the bioceramic coatings. Furthermore, the sintering effect on adhesion was also evaluated and the highest adhesion as 25.8 MPa has been reached at 750°C for 90 s and 5°C min–1 sintering conditions. It was found that using iodine as EPD dispersant has increased the charging ability of the B–HA powders in the suspension and hence eased deposition rate. The study revealed that boron-containing hydroxyapatite coatings can provide crack-free surfaces that providing high adhesion and hence increase the corrosion resistance of metallic implants. Through the results, it was also shown that the network between powders was improved and hence adhesion was increased with increasing B addition.