The microstructure and specific properties of La/HAP composite powder and its coating

La/HAP composite powder, a novel bioactive material, was prepared using co-precipitation method. The La/HAP coating was obtained for the first time through the dip-coating method, starting from the sols of La/HAP and TiO2 particles. The compositions and coating of as-produced La/HAP composite powder sintered at temperatures from 300 to 750 °C were analyzed by means of X-ray diffraction (XRD). The changes of the ion groups in as-prepared La/HAP composite powder were characterized by using Fourier transform infrared (FTIR) spectroscopy. Their surface morphologies were observed by means of scanning electron microscope (SEM). The results show that the La/HAP composite powder has higher thermostability than pure HAP powder and La can refine HAP particle and restrain the decomposition of HAP. Consequently, in coating process the heat-treatment temperature is lower (750 °C) using the synthesized La/HAP powder than that using pure HAP (900 °C). The La/HAP coating mainly contains HAP, TiP or Ti3P5 and TiO2 phases as well as a little CaTiO3 crystal, a very ideal composition to enhance bioactivity of biomaterials. These unique properties of the La/HAP composite powder are beneficial to enhance the strength and bioactivity of coating when it is used as a starting material in coating process.