Abstract
Zr-based thin film metallic glass (TFMG) exhibiting the unique properties of good glass forming ability (GFA), corrosion resistance, and biocompatibility can be applied in various novel fields of industries. In addition, an ultra smooth surface is obtained with the TFMG coatings, which is beneficial to modify the surface condition of stainless steel and can be extended to medical appliances such as surgical blades and micro-surgery scissors. Since the thin film materials are customarily employed to biomedical applications and micro-electro-mechanical system (MEMS), the improvement of mechanical properties and functionality of thin film metallic glass is imperative. The aims of this study are to fabricate the antimicrobial TFMG coatings onto SUS304 plates and to investigate the characteristics of coatings with various substrate temperatures. The amorphous matrix and cluster structure are slightly affected by the processing temperatures due to high cooling rate during deposition and superior glass-forming ability (GFA). All the coatings exhibit similar structural and thermal properties, yet the hardness and elastic modulus can significantly increase to 7.1 GPa and 135 GPa, respectively, with increasing the processing temperature up to 400 oC, well above the values of 4.7 GPa and 109 GPa at room temperature. The enhancement of mechanical properties are attributed to the shortening of average atomic distance, the increase of the short range ordered clusters and the vanish of free volumes. Liquid culture methods and plate counting methods are used to assess the antimicrobial performance of specimens. The antimicrobial rate against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) under JIS standard is over 99%. The results show that the surface of SUS 304 stainless steel substrate can be modified with deposited Zr-Cu-Ni-Al TFMG, and their improved antimicrobial efficacy against those bacteria is attributed to their amorphous rough surface, hydrophobic properties and released copper ion. In addition, the phenomenon of interaction between TFMG and bacteria has also been discussed. The TFMG developed in this study with adequate hardness, good glass forming ability and antimicrobial efficiencies can be used as a promising candidate to improve the surface properties of the medical appliances and also to reduce the possibility of nosocomial infection.