Enhanced adhesion and anticorrosion of silk fibroin coated biodegradable Mg-Zn-Ca alloy via a two-step plasma activation

[Display omitted] •Silk fibroin coated MgZnCa alloy structure without conversion layer was achieved via a two-step plasma activation.•The two-step activation contributed to the significantly increased adhesion force compared to other coating strategies.•The corrosion resistance of coated sample by two-step activation was significantly improved, retarding pitting corrosion. Based on a two-step plasma surface activation process (O2 followed by N2 plasma), silk fibroin coating was prepared on Mg-Zn-Ca alloy without conversion layer to retard the corrosion. This method achieved homogenized surfaces with better hydrophilicity and increased functional groups, significantly improving the adhesion force. The corrosion resistance of coated magnesium alloy was significantly enhanced compared to that of bare samples. Nanoscratch combined with corrosion behavior indicated that the remarkably improvement of anticorrosion ability attributed to the protective layer and the increased adhesion force. Our findings provided more possibilities for corrosion protection of degradable metals.