Plasma electrolytic oxidation(PEO)is considered as a cost effective and environmentally friendly surface treatmentprocess for improving surface properties of light alloys.The formation of ceramic coatings on Ti6Al4V a...Plasma electrolytic oxidation(PEO)is considered as a cost effective and environmentally friendly surface treatmentprocess for improving surface properties of light alloys.The formation of ceramic coatings on Ti6Al4V alloy was reported bytwo-step PEO process and its structural,electrochemical and mechanical properties with the coated samples were compared byone-step PEO process in an alkaline electrolyte.The structural properties were studied using field-emission scanning microscope(FESEM)and X-ray diffraction(XRD).Electrochemical studies were carried out using linear polarization method and in additionmechanical behaviors were investigated by means of Knoop microhardness and nanoindentation method.Results showed that thesecond step process resulted in an increase of both porosity percentage and average pore diameter on the surface.The two-stepprocess resulted in a small increase of thickness from about12.5to13.0μm.Electrochemical test results showed that applying thesecond step resulted in the decrease of both polarization resistance from1800.2to412.5kΩ/cm2and protection efficiency from97.8%to90.5%.Finally,the nanoindentation results indicated that the PEO coatings became softer but more ductile after applyingthe second processing step in acidic electrolyte.展开更多
基金International affairs department of University of Tehran and Sarkhoon & Qeshm Gas Treating Company for the financial support of this study
文摘Plasma electrolytic oxidation(PEO)is considered as a cost effective and environmentally friendly surface treatmentprocess for improving surface properties of light alloys.The formation of ceramic coatings on Ti6Al4V alloy was reported bytwo-step PEO process and its structural,electrochemical and mechanical properties with the coated samples were compared byone-step PEO process in an alkaline electrolyte.The structural properties were studied using field-emission scanning microscope(FESEM)and X-ray diffraction(XRD).Electrochemical studies were carried out using linear polarization method and in additionmechanical behaviors were investigated by means of Knoop microhardness and nanoindentation method.Results showed that thesecond step process resulted in an increase of both porosity percentage and average pore diameter on the surface.The two-stepprocess resulted in a small increase of thickness from about12.5to13.0μm.Electrochemical test results showed that applying thesecond step resulted in the decrease of both polarization resistance from1800.2to412.5kΩ/cm2and protection efficiency from97.8%to90.5%.Finally,the nanoindentation results indicated that the PEO coatings became softer but more ductile after applyingthe second processing step in acidic electrolyte.
