Control of Surface Degradation on Biodegradable Magnesium Alloys by Plasma-Based Technology

Despite the tremendous potential of biodegradable magnesium alloys in surgical implants, the intrinsic degradation rates of Mg-based biomedical implants may be too fast in the physiological environment, particularly in the early stage after surgery. This shortcoming has been hampering wider clinical applications. In this respect, surface modification by plasma-based techniques is a good means to tailor the surface structure and degradation rate of magnesium alloys. The work conducted in the Plasma Laboratory of the City University of Hong Kong in the past two to three years in this area is summarized and discussed in a chronological order in this paper. Different physiologically important elements such as aluminum, titanium, oxygen, zinc, and chromium have been plasma implanted into various biomedical magnesium alloys to alter the surface chemistry and corrosion behavior. This paper discusses the roles played by these plasma-implanted elements and the subsequent effects pertaining to the control of surface degradation from the perspective of orthopedic and cardiovascular applications.