Functional properties of the novel hybrid coatings combined of the oxide and DLC layer as a protective coating for AZ91E magnesium alloy

[摘要] Magnesium alloys are essential materials for aircraft applications however their corrosion protection is still a challenge and restriction from the spread of the applications. Owing to there is still need to search a new way to protect magnesium alloys from corrosion in replacement of currently used chromate coatings which manufacturing process is dangerous and harmful for living organism and will be soon forbidden by law restrictions. In this work, the novel surface modification of magnesium alloy AZ91E was realized. A novel hybrid coating made by combining of the oxide and Diamond-Like Carbon (DLC) layer were elaborated and explored to find out is there any improvements in functional properties when compared to chromate coatings. The corrosion testing in 3.5% NaCl solution and salt fog condition revealed the clear improvements in corrosion protection of AZ91E alloy. Additionally, It was found that oxide coating has lower microhardness and young modulus when compared to DLC and thus it decreases internals stress within the hybrid coating. The wear test revealed that DLC coating significantly improves abrasion resistance when compared to raw, unmodified AZ91 or AZ91E covered with chromate coating.

[发布日期] 2019-12-25

[关键词] Coating;Plasma electrolytic oxidation;Diamond-like carbon;Corrosion;Wear;Magnesium alloy