Preparation of phosphate conversion coating on laser surface textured surface to improve corrosion performance of magnesium alloy

Highlights: • Multimodal surface roughness and high specific area generated by LST facilitate the deposition of PCC. • LST pretreatment reduce the defects and increase the adhesion of PCC. • The PCCs with the LST pretreatment exhibit excellent corrosion resistance. -- Abstract: In this work, we proposed a surface modification strategy to improve corrosion resistance of magnesium alloy by combining laser surface texturing (LST) with phosphate conversion coating (PCC). The surface and section morphologies, adhesive performance and electrochemical corrosion properties of the coated samples were investigated. Results demonstrate that the multimodal surface roughness and high specific area generated by LST facilitate the deposition of coating, increase the adhesion of coating and reduce the shedding rate of coating in the scratch test. Electrochemical analyses reveal that the coated sample with LST pretreatment shows superior corrosion properties, and fewer areas were damaged by corrosive medium compared with the coated sample without LST. Immersion test results reveal that LTC sample shows the best long-term corrosion resistance among all samples.The underlying mechanisms of the PCC with LST pretreatment to improve the anticorrosive performance of Mg alloys are proposed.