Magnesium alloy, as an absorbable and implantable biomaterial, has been greatly developed in the application field of biomaterials in recent years due to its excellent biocompatibility and biomechanics. However, due to the poor corrosion resistance of magnesium alloy in the physiological environment, the degradation rate will be unbalanced, which seriously affects the clinical use. There are two main ways to improve the corrosion resistance of magnesium alloy: one is by adding alloying elements, the other is by surface modification technology. Compared with adding alloy elements, the surface coating modification has the following advantages: (1) The surface coating modification is carried out without changing the matrix elements of magnesium alloy, avoiding the introduction of other elements; (2) The corrosion resistance of magnesium alloy can be improved by relatively simple physical, chemical, or electrochemical improvement. From the perspective of corrosion resistance and biocompatibility of biomedical magnesium alloy materials, this paper summarizes the application and characteristics of six different surface coating modifications in the biomedical magnesium alloy field, including chemical conversion method, micro-arc oxidation method, sol-gel method, electrophoretic deposition, hydrothermal method, and thermal spraying method. In the last section, it looks forward to the development prospect of surface coating modification and points out that preparing modified coatings on the implant surface combined with various modification post-treatment technologies is the main direction to improve biocompatibility and realize clinical functionalization.

Magnesium alloy has great potential as a new medical metal material because of its good biocompatibility and biodegradability. However, because of the active chemical properties of magnesium alloy, it is easy to react with oxygen and cutting fluid to release hydrogen. In this paper, by cutting magnesium alloys prepared under different cooling conditions, the phase composition of the machined surface was studied. Tensile strength and elongation were studied through tensile experiments at different temperatures. The effect of cryogenic milling on the service performance of a magnesium alloy machined surface was studied by the friction and wear test and electrochemical corrosion test. The results show that cryogenic milling contributes to the formation of the second phase of magnesium alloy, which has the effect of corrosion resistance, and has better tensile strength and elongation. Through the friction and wear test, it is found that the average friction coefficient decreases by about 7.4%, and the wear amount decreases by about 10% in the liquid nitrogen cooling environment. Through the electrochemical corrosion test, it was found that the oxide film formed in the liquid nitrogen cooling environment was more compact and uniform, and the crystal refinement of the surface layer was better.