Polymer-assisted deposition of hydroxyapatite coatings using electrophoretic technique

Hydroxyapatite (HA) finds use as powder, scaffold, paste, and coatings for orthopedic and dental applications. Plasma spraying is the most commonly used technique to coat HA on metallic implants. However, undesirable phase changes at high temperatures encourage to adopt ambient temperature deposition techniques such as dip coating, electrophoretic, and physical vapor deposition (PVD). Electrophoretic technique is being used extensively to deposit HA, however sintering is required after the deposition to enhance adhesion of coatings to the substrate. In the present work, polyethylene glycol (PEG) modified HA was deposited on 316L Stainless Steel plates using electrophoretic deposition (EPD), which improved the binding strength of the HA to the substrate with increased packing density of HA particles without the need of sintering. PEG is a biocompatible and soluble polymer that helps HA to bond well with the substrate and in addition, prevents the agglomeration and precipitation of HA. Phase identification and crystal structure of the coatings were determined using X-ray diffraction (XRD). The stability of the coatings was assessed by Fourier transform infrared spectroscopy (FTIR), whereas scanning electron microscopy (SEM) was utilized in order to investigate the morphological properties of the deposited coatings. The mechanical properties of the coatings were investigated using the indentation testing that depicted an enhanced level of adhesion of coatings to the substrate. © 2014 National Taiwan University