Composition and hardness of mullite coatings formed with direct current power supply on LY12 aluminum alloy surface

摘要

The surface modification of aluminum and its alloys using plasma technology is increasingly being investigated.Thick ceramic coalings with high hardness on aluminum alloys can be prepared successfully using a micro-plasma oxidation(MPO)technique.In this work,the composition,microstructure and elemental distribution of ceramic coatings formed by MPO on LY 12 aluminum alloy and its hardness are investigated using XRD,EPMA and microhardness instruments.The results show that the ceramic coatings consist of mullite,gamma - Al_2O_3 and a lot of amorphous matter.The content of silicon in the coatings increases from interface to the coatings,however,the content of aluminum decreases along this direction.The maximum hardness of ceramic coatings is up to 9.2 GPa.