Effect of DC Mode Current Density on Properties of Micro-Arc Oxidation Film on Aluminum Lithium Alloy

Abstract

In order to study the influence of electrical parameters on the film formation mechanism and film properties of aluminum-lithium alloy micro-arc oxidation in DC mode，2195 aluminum lithium alloy was used as the research object to prepare micro-arc oxidation ceramic film in a silicate phosphate alkaline electrolyte system under different current densities in a DC steady current mode.The surface and cross-sectional morphology， elemental composition and phase composition of micro-arc oxidation film were analyzed by scanning electron microscopy (SEM)，energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD).The corrosion resistance and wear resistance of different ceramic film were measured by using an electrochemical workstation and a friction and wear tester.Results showed that the ceramic film mainly contained O，Al， Si， and P elements， and the phase composition of the film layer was mainly γ-Al2O3 and a small amount of α-Al2O3.In the range of current density 4～16 A/dm2， with the increase of current density，the corrosion resistance and wear resistance of the film layer first increased and then decreased.When the current density was 8 A/dm2， the as-prepared film possessed the optimal corrosion resistance， with the self-corrosion current density of 5.171 8×10-7 A/cm2 and the dense layer resistance Rb of 3.323×104 Ω·cm2.When the current density was 8 A/dm2，the as-prepared film had the best wear resistance， and the wear mechanism was a mixture of fatigue wear and abrasive wear， with a wear rate of 0.343 75×10-6 cm3/(N·m).

Keywords

• aluminum lithium alloy|dc power supply|micro-arc oxidation|abrasion resistance|corrosion resistance