Effects Of Electrical Parameters On Local Arc Ablation Of Magnesium Alloy By Micro-arc Oxidation

In the Micro-arc oxidation of magnesium alloy,voltage,frequency and duty ratio of electrical parameters are important factors affecting local sustained arc ablation phenomenon,different load characteristics will affect the power output characteristics,local continuous arc erosion tendency will be different.This paper is based on the AZ31 B magnesium alloy as matrix material,by self-developed high power pulse power supply unipolar pulse output mode.changing the pulse frequency and duty ratio,A,B sample surface area of different experimental Micro-arc oxidation,voltage waveform and ablation voltage data recorded during experiment,to study the effect of different electrical parameters and different load characteristics on the ablation phenomenon.The same duty ratio,frequency in the range of 100Hz~1000Hz,at the ends of the frequency ablation phenomenon is more likely to occur,the ablation voltage is near the ends of the lower and intermediate frequency samples less prone to erosion phenomenon.At the same frequency,with the increase of duty cycle,more cooling time is needed for the increase of arcing time,while the duty cycle increases cooling time and ablation at lower voltage.The Micro-arc oxidation of magnesium alloy specimens with different surface areas has different load capacitance characteristics,and the larger the surface area of the sample is,the stronger the load capacitance characteristics are.The load characteristics of the same sample during the Micro-arc oxidation process will change at any time.With the increase of the film thickness,the discharge constant of the load is larger,and the tendency of local continuous arc ablation will be greater.It is found that the local sustained arc ablation is not only related to the duration of arcing time and cooling time,but also to the relative proportion of them.The strong capacitive capacity is the fundamental cause of local sustained arc erosion,and the load with different surface areas has different capacitance characteristics.The appropriate electric parameters can be selected according to the surface area of the load to avoid the occurrence of local continuous arc ablation and to guide the setting of the electrical parameter process.