Effect of coating thickness on the cutting sharpness and durability of Zr-based metallic glass thin film coated surgical blades

The cutting sharpness and durability of commercial blades without and with 200-500 nm thicknesses of Zr-Cu-Al-Ag-Si and Zr-Cu-Ni-Al-Si metallic glass thin film (MGTF) coating were systematically characterized and evaluated. The amorphous states of all MGTF coatings were examined by grazing incident X-ray diffraction analysis. The observation of scanning electron microscopy reveals that MGTF coated blades own much smoother surface than the commercial one which indicates smaller friction force during cutting process. Results of sharpness test in the beginning reveal that all MGTF-coated blades possess smaller value of blade sharpness index (BSI) than the commercial one. The cutting durability of the MGTF-coated and commercial blades was evaluated by the variation of BSI values by 25 cm cutting test. The commercial blade was blunted (BSI = 0.49) after 20 cm cutting path. Conversely, the 300 nm-thick MGTF-coated blades present the smallest BSI value after 20 cm cutting path in comparison with other thicknesses MGTF-coated blades and commercial blade. As a result, the cutting durability of surgical blade can be significant improved by Zr-based MGTF-coating, can keep the BSI value less than 0.45 after 20 cm cutting test.