Effect of UV irradiation and diffuse plasma on surface properties of micro-arc calcium phosphate coatings

摘要

The influence of UV irradiation or plasma of runaway electron preionized diffuse discharge (REP DD) post-modification on the surface properties of the calcium phosphate (CaP) coatings formed by the micro-arc oxidation (MAO) method was investigated. The formed MAO-coatings had porous structure and rough surface morphology with incorporation of spheroidal structural elements with inner pores. It was showed that the UV irradiation or REP DD post-treatment of the MAO-coatings led to the decrease of the coating contact angels with water from 20 to 0 or to 7 degrees, respectively. However, the free surface energy of the coatings did not change after post-treatments and equalled to 74±1 mJ·m~(-2). The polar component of the free surface energy of the all types of the coatings exceeded almost 5-6 times the dispersion component that indicated the presence of strong polar bonds on the coating surface, e. g. OH- and PO_4-groups.