On the role of microstructure form and dimension in surface energy changes in a magnesia partially stabilized zirconia bioceramic following CO₂ laser irradiation

This work elucidates the basic mechanisms active in microstructure and the associated surface energy for a widely used bioinert ceramic, magnesia partially stabilized zirconia (MgO-PSZ) following CO₂ laser treatment. CO₂ laser irradiation results in rapid heating of the surface and consequently leads to the surface densification and crystal growth in the melted layer of the MgO-PSZ. There was an increase in the tetragonal phase after CO₂ laser treatment and columnar crystal structure in the upper-most layer and irregular grain in the heat affected zone. Various power densities of laser treatment brought about different microstructures on the modified MgO-PSZ. Contact angle measurement of a set of test liquids was used to estimate the surface energy of the MgO-PSZ before and after CO₂ laser treatment. It was found that the surface energy of MgO-PSZ had been enhanced after CO₂ laser treatment and its increase was related to the phase change (represented by microstructure) and crystal size of MgO-PSZ.