Characterization of UHMWPE- HAp coating produced by dip coating method on Ti6Al4V alloy

In the present study, the surface of Ti6Al4V alloy was coated with UHMWPE-HAp composite film by dip coating for hip joint material. Ti6Al4V alloy surfaces were firstly roughened by anodic oxidation to provide adhesion of the polymer coating on it. Scanning Electron Microscope (SEM) and Field Emission Scanning Electron Microscope (FE-SEM) results showed that the UHMWPE-HAp composite film was coated homogenously on the substrate and HAp particles were well bonded to the matrix. Functional groups and bond types of the composite coatings were detected by Fourier-transform Infrared Spectroscopy (FTIR). The melting temperature T m and the enthalpy of fusion (Delta H-f) of the UHMWPE and UHMWPE-HAp composite coatings were measured by differential scanning calorimetry (DSC). The crystallinities were calculated as 24.5% for pure UHMWPE and increased to 54.2% by addition of 1 wt%HAp particles into the UHMWPE matrix. Dry sliding wear properties of coatings against alumina ball were tested by a ball-on-disc tribometer in linear mode. Wear results revealed that UHMWPE-HAp composite coating on anodic oxidized Ti6Al4V alloy has an ultra-low friction coefficient of 0.06 compared to the friction coefficient of anodic oxidized Ti6AlV4 alloy at of 0.8 and with a favorable wear resistance 84% higher than oxide coated ones. This newly developed composite coating material shows potential use for artificial hip joint replacements.