Investigations of mechanical properties of SiO₂ coatings deposited by sol-gel method on cpTi and Ti-6Al-7Nb alloy

One of the methods used to improve the hemocompatibility of titanium-based biomaterials is to apply sol-gel method to form thin oxide films. Such films have increased hemocompatibility, which greatly reduces the risk of complications related to intravascular coagulation. Another important issue related to the generation of surface films is providing the proper set of mechanical properties. For this reason, mechanical properties of SiO₂ films deposited on the surfaces of titanium Grade4 and Ti-6Al-7Nb titanium alloy test pieces were studied. In order to assess the mechanical properties of films generated using the sol-gel method, hardness and adhesion of these layers to the metal substrate were tested. First, the Oliver Pharr method was used to measure the instrumental hardness. Subsequently, scratch tests were performed to study film adhesion to the surface. Both tests, hardness and scratch strength, were performed using an open platform equipped with CSM Microcombi Tester. Based on the obtained data, it was found that thickness of the studied surface films varied depending on the process parameters of their formation, and their mechanical properties changed accordingly. The obtained results have direct impact on the optimisation of SiO₂ layer generation using the sol-gel method on surfaces of titanium-based implants used for contact with blood, and consequently on improvement of their functional properties.