Laser Coating of HAp/Ti Nanoparticles on Metal Implants: Interfacial Bonding Strength, Chemical Analysis and Biocompatibility

In this paper, laser coating of hydroxyapatite (HAp) and Ti nanoparticles on Ti-6Al-4V implants was developed. An Nd:YAG laser was used to coat multilayers of HAp and Ti nanoparticles on implants. This coating process has the following advantages: (1) low temperature coating of nanoscale HAp is realized due to good sinterability of titanium nanoparticles; (2) high interfacial strength between layer and substrate because of the functional multilayer coating; (3) HAp nanoparticles provide better biocompability than micro-particles; (4) biphasic calcium phosphate (BCP) could be introduced, which has been reported to have excellent biocompatibility. In order to achieve these goals, careful selection of laser processing parameters is required. A multiphysics model is built and validated with experiments. This model is employed to determine the appropriate laser processing conditions. After laser processing, the features of the coated samples were characterized, including microstructures, chemical compositions, surface roughness, structure porosity and interfacial bonding strength. Qualitative cell culture studies with osteoblast-like UMR-105 cells were carried out to reveal the biocompatibility of so-coated implants. It is found that multilayer laser coated nanoHAp/Ti implants has beneficial biocompatibility, surface roughness, maintained chemical composition, porous microstructure and strong coating/substrate interfacial strength.