Scientists improve properties of nano hydroxyapatite coatings in implants

Iranian materials engineering experts studied the mechanism to increase the stability of hydroxyapatite nanoparticles’ suspension by using triethanolamine (TEA) additive, its effect on the electrophoretic deposition process and the properties of the obtained coatings. Results of the research can be used in the cost-effective production of nanostructured hydroxyapatite (HA) coatings on metallic implants. Among other applications of the research, mention can be made of the creation of colloid suspensions of HA nanoparticles with high stability in processes, including slurry casting or tape and pressure casting. The research consisted of the following steps; HA nanopowder was firstly synthesized through wet chemistry method and the suspensions of the nanoparticles in isopropanol were prepared at various concentrations of TEA. Zeta potential of the particles were measured in the prepared suspensions and the in-situ kinetics of deposition formation in the suspensions were measured by using a scale with accuracy of 0.1 mg at 60 V. Wet density of the produced coatings were measured through Archimedes method. The microstructure of the coatings was investigated by using optic and electron microscopes. Finally, the resistance against corrosion in the produced coatings was calculated through electrochemical polarization method. The use of nanoparticles in electrophoretic process creates more homogenous coatings that agglomerate at lower sintering temperature. The suspension made of nanoparticles has higher stability but lower rate of sedimentation in comparison with micrometric particles, which is a result of the lower weight of nanoparticles compared to that of microparticles. Results of the research have been published in Ceramics International, vol. 39, February 2013, pp. 7007-7013.