Study On The Preparation And Properties Of Micro-arc Oxide Film Of Titanium Alloy Plating

In this paper,multi arc ion plating and micro-arc oxidation technology were applied on TC4 titanium alloy to produce a composite ceramic layer with Al₂O₃ in order to enhance the wear resistance and micro-hardness of TC4 titanium alloy.By changing the thickness of multi arc ion plating aluminum layer so as to select appropriate thickness of aluminized layer thickness for subsequent process of micro-arc oxidation,then keep the thickness of aluminized layer and change the micro-arc oxidation time to determine the optimum micro-arc oxidation time by compare the combination property.The microstructure morphology of ceramic layer were observed by scanning electron microscope?SEM?,the composition of ceramic layer were analyzed by energy dispersive spectrometer?EDS?,the phase composition of ceramic layer were measure by X-ray diffraction?XRD?,the wear resistance of ceramic layer were tested by friction and wear tester,the adhesive strength of ceramic layer were measure by tensile test,and the corrosion resistant performance of ceramic layer were compared by salt spray test and electrochemical experiments.The results showed that when the thickness of multi arc ion plating aluminum film were20?m,30?m,40?m,50?m respectively,the micro-arc oxidation time fixed for 4h,the optimum thickness of multi arc ion plating was 40?m while the electrolyte formula of micro-arc oxidation were 10g/L Na₂SiO₃ with 5g/L KOH.In this condition,the aluminized layer just completely oxided,the structure of membrane surface was density with less membrane layer defect,and the film hardness was high.Under the same electrolyte formula,the aluminized layer thickness maintain 40?m,the time of micro-arc oxidation set for 2h,3h,4h respectively,the optimal micro-arc oxidation time is 3h.By using the scanning electron microscope,there was 10?m aluminum plating residual without oxided,while the aluminum plating layer is metallurgical combination with matrix,there was less surface defects,with less perfoliate crack,and almost none large pore,the sintered micro-porous were closed distribution,just like the shape of the crater.At the same time,when MAO time is 3h,the ceramic layer obtain the highest micro-hardness,which is about 1261 HV.Through XRD,the composite of ceramic oxide film were mostly alpha A1₂O₃,while the composite of porous layer were almost?-A1₂O₃.Under the same optimal parameters,compared the properties of micro-arc oxide film and untreated TC4 titanium alloys by micro-hardness and friction and wear test,it can be concluded that the hardness increased 5 times or so and the friction coefficient reduced from 0.82 to 0.63,the wear quantity is reduced 2 orders of magnitude compared to TC4 titanium matrix.Through salt spray test,the corrosion resistance of titanium alloy aluminum plating layer under different time micro-arc oxidation can be ordered:3 h>2 h>4 h.