Characteristics and Surface Serviceability for Cryogenic Milling Mg-1.6Ca-2.0Zn Medical Magnesium Alloy

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.