The effect of complexing agent on Ti alloy micro-arc oxidation(MAO) coatings in Ca-P electrolyte

Abstract

Three new microarc (MAO) ceramic coatings were fabricated in the Ca-P electrolyte with three eco-friendly easily degradable complexing agent GA, TEA and EDTMPS and compared to that fabricated with the current common agent EDTA–2Na. A 3-Dimensional video microscope and scanning electro microscope were utilized to observe surface and cross-sectional morphology; the statistics of the coating surface were measured by the image software Image J × 2.0. Compositions of elements and phases were detected by the energy-dispersive X-ray spectroscopy and X-ray diffraction, respectively; X-ray photoelectron spectroscopy was further applied to provide more information about the components of the four complexing agents for MAO coatings surfaces. The surface morphologies show difference, which is a result of different quantity of melting metal during the treatment. The EDS results indicate that the elements compositions of the four MAO ceramic coatings are similar. The phases show little difference which is a result of the crystal transformation of TiO₂ in different physical characteristic electrolytes. The biocative tests of four complexing agent MAO coatings shows good bioactive performance. The surface morphology of MAO coatings could meet the demand of biological implanting. Corrosion resistance properties are improved effectively in simulated body fluid (SBF). The wetting angles are less than 90 degrees, which indicates better solid-liquid affinity. After 28 days of sedimentation experiments in SBF, the white substance-carboxyl apatite (HA) generate on the surface of the coatings. The biological activities of the four MAO coating samples are demonstrated.