Characterization of ZrC coatings deposited on biomedical 316L stainless steel by magnetron sputtering method

Abstract

ZrC coatings were fabricated on 316L stainless steel (316L SS) by radio-frequency (RF) magnetron sputtering at different substrate temperatures (Ts). The phase configuration, microstructure and mechanical properties of ZrC coatings were investigated by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), atomic force microscopy (AFM), TriboIndenter hardness tester and scratch tester. The corrosion resistance in phosphate buffered saline (PBS) and the hemocompatibility of ZrC coatings were evaluated by potentiodynamic polarization and platelet adhesion test. The XRD results indicated that the microstructure of ZrC coatings was affected by Ts. The ZrC phase with (111) preferred orientation was formed when Ts was 400°C, which exhibited in the form of particulates with the crystallite sizes of about 5nm. AFM results showed that with the increase of Ts, the root-mean-square (Sq) values of the ZrC coatings decreased and the distribution of the particle size became narrower. The results of nano-indentation tests indicated that Ts has no effect on the hardness and elastic modulus of ZrC coatings. The scratch test results demonstrated that ZrC coatings deposited above 200°C exhibited good adhesion performance. The potentiodynamic polarization and platelet adhesion test results showed that the ZrC coatings deposited at Ts of 200°C and 400°C possessed better corrosion resistance and hemocompatibility than those deposited at Ts of 25°C. It is indicated that the hemocompatibility of ZrC coatings deposited on the 316L SS was influenced by the surface roughness, hydrophilicity and the surface energy of the coating.