Silver/calcium phosphate composite coating on gold substrate by occlusion electrodeposition technique

Calcium Phosphate (CaP) is a double salt of tricalcium. phosphate and calcium hydroxide is the principal inorganic constituent of human bones and teeth, HA for load bearing applications is not feasible because of its brittleness and relatively low strength. HA or similar CaP surface result in earlier stabilization of the implant in surrounding bone and can be used as a coating on a stronger metallic material. There are several coating techniques that can be used for coating CaP on substrates, they include Dip Coating, Immersion Coating, Hot Isostatic Pressing (HIP), Ion Beam Sputter Coating, Plasma Coating, Electrophoretic deposition etc. Among these processes plasma spraying is the most commonly used to coat implants with HA, however, there are some disadvantages of plasma coating process. The coatings are not 100% crystalline, it is a line of sight process, there is poor mechanical bond strength between coating and substrate etc. Electrochemical methods offer a low cost, precise method of coating irregular surfaces. In this current study a new electrodeposition technique is used to coat the implant material. The Occlusion electrodeposition technique is a recent development in which inert particles are codeposited with a metal ion. In this technique an electrolytic bath of Ag+ is chosen, where the silver ion is an effective antimicrobial metal ion and has a remarkably low human toxicity. In addition silver is inert and there is no chemical reaction with CaP and it helps bind the CaP on to the substrate resulting in the formation of a composite coating. In this study the effect of various process variables (applied potential, concentration of electrolyte, concentration of CaP, time of deposition) on the coating thickness is studied. In vitro studies of the coated sample were conducted to examine the behavior in simulated body fluid (SBF).