Nanomechanical behavior, adhesion and wear resistance of tin oxide coatings for biomedical applications

Abstract

Abstract This study investigates the properties of tin oxide coatings employed in biomedical applications. The films were deposited on a clean glass substrate, preheated at 450 °C, applying the spray pyrolysis technique as the latter produces crystallized thin films without the need for further heat treatment. X‐ray diffraction analysis showed that tin oxide films had a tetragonal structure characterized by a preferential orientation (111). The measurements of reflectance and transmittance revealed a wide optical band gap of 4.0 eV. Nanoindentation tests showed that the tin oxide coating, with a hardness of 5.9 GPa and a Young's modulus of 78 GPa, exhibited elastic‐plastic behavior. In addition, tribological tests indicated that tin oxide coating had a very low coefficient of friction (μ=0.06), high wear resistance (wear rate 2.10 −5 mm 3 N −1 m −1 ) and good adhesion to the substrate (critical adhesion load of 5.55 N). It was also noticed that tin oxide thin films had antibacterial activity due to their nanocrystalline impurities. These properties make tin oxide perfectly acceptable for biomedical applications.