Wetting and bonding characteristics of selected liquid metals with a high–power diode–laser–treated alumina bioceramic

Abstract

Changes in the wettability characteristics of an alumina bioceramic occasioned by high–power diode–laser (HPDL) surface treatment were apparent from the observed reduction in the contact angle. Such changes were due to the HPDL bringing about reductions in the surface roughness, increases in the surface O2 content and increases in the polar component of the surface energy. Additionally, HPDL treatment of the alumina–bioceramic surface was found to effect an improvement in the bonding characteristics by increasing the work of adhesion. An electronic approach was used to elucidate the bonding characteristics of the alumina bioceramic before and after HPDL treatment. It is postulated that HPDL–induced changes to the alumina bioceramic produced a surface with a reduced band–gap energy, which consequently increased the work of adhesion by increasing the electron transfer at the metal–oxide interface and thus the metal–oxide interactions. Furthermore, it is suggested that the increase in the work of adhesion of the alumina bioceramic after HPDL treatment was due to a correlation existing between the wettability and ionicity of the alumina bioceramic, for it is believed that the HPDL–treated surface is less ionic in nature than the untreated surface and therefore exhibits better wettability characteristics.