Growth characteristics of micro-plasma oxidation ceramic coatings on Ti alloy by inductively coupled plasma-atomic emission spectrometer technique

The aim of this work was to study the growth characteristics of micro-plasma oxidation ceramic coatings on Ti–6Al–4V alloy. Compound ceramic coatings were prepared on Ti–6Al–4V alloy by pulsed micro-plasma oxidation (MPO) in NaAlO2 solution. The phase composition and surface morphology of the coating were investigated by X-ray diffractometry and scanning electron microscopy. The solution of Ti from the substrate and the content of Al in the electrolyte were studied by inductively coupled plasma-atomic emission spectrometer (ICP-AES) technique. Ti from the substrate dissolved and came into the coating and the electrolyte during MPO process. The content of Ti in the electrolyte under the pulsed bi-polar mode was more than that of the pulsed single-polar mode. The phase composition and structure of the coating was attributable to the space steric hindrance of Al congregated on the electrode surface due to the effect of the electric field and the electrolyte characters. For the pulsed single-polar mode, the coating was mainly composed of a large amount of a-Al2O3 and a small amount of g-Al2O3. And the coating was mainly structured by Al from the electrolyte. However, the coating was composed of a large amount of Al2TiO5 and a little a-Al2O3 and rutile TiO2 for the pulsed bi-polar mode. And the coating was structured both by Ti from the substrate and Al from the electrolyte