Preparation And Properties Of Ceramic Coating By Plasma Electrolytic Deposition On Metal Surface

Plasma electrolytic deposition?PED?is a kind of novel and effective surface engineering technique that can be used to prepare metallurgically bonded ceramic coatings on metals,and it has the advantages of simple process,short processing time,environment friendly and wide application scope.In recent years,this technology has been given a wide attention by researchers in material field and enterprisers in metal product manufacturing field and made some development and breakthrough in the process and mechanism.However,there are still plenty of projects to research no matter in theory and engineering technology.Main research aspects included in this dissertation are 1)preparation and properties of blue ceramic coating by micro-arc oxidation on aluminum alloy;2)synthesis of Al₂O₃-Y₂O₃ ceramic coatings on FeCrAl wire via cathodic plasma electrolysis.At the same time,the microstructure,composition and formation mechanism of coatings were tested and analyzed by XRD,SEM,EDS and other means.Blue ceramic coating was prepared on 5052 aluminum alloy by micro-arc oxidation in the paper.We systematically investigated the effects of the Co?OH?₂ concentration and the applied voltage on the microstructure and the corrosion resistance.The results show that the phase structure is mainly?-Al₂O₃.As the Co?OH?₂ concentration and voltage increased,the blueness degree of coatings gradually deepen,and the color is the darkest during Co?OH?₂ additive 3.0 g/L.Meanwhile,the surface tends to close and becomes denser.The corrosion resistance of ceramic coating is best during Co?OH?₂ additive 1.0g/L when the voltage was140V.Al₂O₃-Y₂O₃ coatings were prepared by cathodic plasma electrolysis on FeCrAl wire.The influences of solution composition and electrical parameters on structure and insulation property of Al₂O₃-Y₂O₃ coatings were studied.The result of XRD indicates that the coating is composed of Al₂O₃ and Y₂O₃.And the thickness of the coating gradually increases with the increase of working voltage,while the bonding becomes poor.As the increasing of reaction time,the thickness and resistance value of Al₂O₃-Y₂O₃ coating increase.Experimental results showed that the bonding state between Al₂O₃-Y₂O₃ coating and substrate was metallurgical and the coating microstructure was dense,continuous and uniform at 110V with deposition for 60?90s,while the resistance value reached 40 M?.