Structure and electrical potential of calcium phosphate coatings modified with aluminum oxyhydroxide nanoparticles

Abstract

The effect of the introduction of charged aluminum oxyhydroxide (AO) nanoparticles into the porous coatings from calcium phosphate formed by micro-arc oxidation on their electrical potential and structure was studied. The modification resulted in changes in the morphology and elemental composition of the coatings. The selection of coating functionalization parameters resulted in obtaining homogeneously distributed aluminum oxyhydroxide nanoparticles in the form of agglomerates, providing the maximum change in the electrical potential of the coatings. An increase in the duration of ultrasonic dispersion (USD) of initial AlN powder suspension from 10 to 60 min and an increase in the surface roughness of the coatings, parameter Ra, from 3.5 to 5.5 µm led to an increase in the surface electrical potential from −85 to −35 mV. At the same time, the aluminum content in the coating decreased from 3 to 1 at.% with an increase in the duration of USD of the AlN powder suspension from 10 to 60 minutes. The introduction of aluminum oxyhydroxide nanoparticles into the coating contributed to an improvement in corrosion properties, namely, an increase in the corrosion potential from 0.1 to 0.2 mV and a decrease in the corrosion current from 2.5 ∙10−9 to 1.1·10−9 A ∙ cm2.