Preparation and characterization of diamond-like carbon (DLC) film on 316L stainless steel by microwave plasma chemical vapor deposition (MPCVD)

The 316L stainless steel was widely used in medical, surgical instruments and human implant medical materials. The diamond-like carbon (DLC) films were deposited on 316L stainless steel by varying temperature, CH4:H2 flow rate, and deposition time in a microwave plasma chemical vapor deposition (MPCVD) system to improve their biocompatibility. The morphology and composition of deposited films were investigated using a scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), and Raman spectroscope. The results showed that with the increase in deposition temperature and the decrease in gas flow ratio, the structure of the film gradually became compact and smooth, and the graphite phase structure of the film tended to change to diamond phase. In addition, the island-like structure gradually grew into a sheet, and the defects in the films were reduced with the enhanced bonding force between the films and the stainless steel matrix. The optimum temperature and gas flow ratios were 900 °C and 10:190, respectively. Medical stainless steels containing DLC films had better bone-forming ability and biocompatibility than untreated.