Degradation Behavior of a Fe-based Amorphous Coating Prepared by Cold Spraying

Although magnesium and magnesium alloys are known as biodegradable medical metals with proper mechanical properties and bio-compatibility, the rapid degradation rate limits their clinical applications. In this paper, Fe78Si9B13 amorphous coatings were prepared on the surface of ZK60A magnesium alloy by using the cold gas dynamic spraying (CGDS) technology. Microstructure, mechanical properties, corrosion resistance, and the degradation behavior of the coatings were investigated. Results show that the coating prepared at 5 MPa and 1073 K has the maximum coating thickness, the lowest porosity, the highest microhardness and contact angle, the most positive corrosion potential, the smallest corrosion current density, and a relatively high volume fraction of amorphous phase. Immersion corrosion experiments show that the degradation rate of the optimal coating is 0.15 mm/a, meeting the requirement of the bone implant material. Degradation behavior analysis shows that bone-like apatite nucleates and rapidly grows into bone-like hydroxyapatite when the sample is immersed in simulated body fluids solution for several days, demonstrating strong biological activity and osteoinductivity of the coating. Furthermore, although pits occurred, electrochemical impedance spectra shows that the coating still keeps a good corrosion resistance immersed in SBF for 15 days.