Design Of Scanning Micro-arc Oxidation Injection System And Research On Film Formation Process

Immersion micro-arc oxidation technology is a relatively mature green surface treatment technology for in-situ formation of ceramic layers on the surface of valve metal such as aluminum-magnesium-titanium and its alloys.However,the power supply and the part protection technology during the process limit the application of this technology in the micro-arc oxidation treatment of large-area parts and the local repair of ceramic layers.The purpose of this paper is to design a small-sized,portable micro-arc oxidation spray device,and based on the system,the scanning micro-arc oxidation process is completed.Based on Solidworks software,the design of portable scanning micro-arc oxidation device was completed.The device is mainly composed of a power supply system,an electrolyte circulating cooling system and a hand-held scanning injection system.The research on the processing technology of the portable scanning micro-arc oxidation device was carried out.For the silicate electrolyte system,the effects of power supply parameters on thickness,hardness,roughness and surface properties were analyzed.The results show that the performance of the ceramic layer is better when the voltage is 525V,the pulse frequency is 300Hz,and the duty ratio is 40%.The microstructure and phase composition of the ceramic layer was characterized by SEM and XRD.There are a large number of discharge holes,particle deposition and small micro-cracks on the surface of the ceramic layer.The layer is mainly composed of?-Al₂O₃ and a-Al₂O₃.The loose layer is more likely to form ?-Al₂O₃ phase.The ?-Al₂O₃ phase begins to appear and increases with the extension of oxidation time.The proportion of thea-Al₂O₃ phase in the dense layer was largerThrough the combination of experiment and simulation,the effect of electrode spacing on the formation of ceramic layer was studied.The electric field strength and voltage simulation results are consistent with the analysis results based on the test data,that is,the smaller the electrode spacing,the smaller the partial pressure of the electrolyte,the stronger the electric field between the electrodes,the stronger the discharge on the surface of the substrate,and the more obvious the discharge spark.