Synthesis and corrosion behavior of a hybrid bioceramic-biopolymer coating on biodegradable Mg alloy for orthopaedic implants

A composite coating composed of octacalcium phosphate (OCP) and hydroxyapatite (HA) as an underlayer and polycaprolactone (PCL) as an overlayer was fabricated on an Mg-1.2Ca-2Zn alloy via combination of chemical solution deposition and dip coating methods. The overlayer was composed of a pore network structure with thickness around 38 mu m but the underlayer consisted of plate-like crystals with inner dense layer (1.2 mu m) and an outer coarse layer (6 mu m). The corrosion current densities of Mg alloy significantly decreased after composite coating from 211.6 to 0.059 mu A/cm(2). Hence, the PCL/OCP/HA composite coating can effectively protect the Mg-1.2Ca-2Zn alloy when used as degradable orthopaedic implants. (C) 2015 Elsevier B.V. All rights reserved.