Thermal oxidation of titanium-based cold spray coatings for biological and wear-related applications ; Biyolojik ve aşınmaya yönelik uygulamalar için soğuk dinamik gaz püskürtme tekniği ile üretilmiş titanyum bazlı kaplamaların termal oksidasyonu

Thesis(Ph.D.) -- Istanbul Technical University, Graduate School, 2022 ; The combination of strength, toughness and ductility makes metallic materials more preferable for engineering applications than ceramics and polymers. But the surface properties of metallic materials are insufficient for some of these applications. Thus, surface modification of metallic materials enables the keeping bulk properties with better surface facilities. In this thesis, the aim is the surface modification of metallic materials (Co-Cr alloy and 316L stainless steel) via cold gas dynamic spraying (CS) system. CS enables the spraying of feedstock powders to the substrate with supersonic velocities. The collusion of powders with the substrate leads to plastic deformation of powders and generates the coating formation over the substrate. Via the CS process, it is possible to deposit metallic, ceramic, polymer and composite coatings on different kinds of substrates. The application of the CS process on metallic materials generally purposes to improve the wear, corrosion and biological performance of these materials. In the scope of the thesis, the surface modification of Co-Cr alloy and S316L Stainless steel handled by Titanium-based CS coatings. With the native oxide film forming on the Titanium and its alloys, these metals show high corrosion resistance and biocompatibility. Nevertheless, the thickness of the native oxide film is approximately 10nm and bad at wear applications. Thus, there is a need for a second treatment to make the oxide film more mechanically and chemically more stable. Thermal oxidation (TO) is a very cheap and practical method for Titanium-based materials' surface modification. TO enables the formation of relatively thick and protective oxide layers on Titanium-based materials. In the scope of the thesis, the feasibility of TO on CS'ed Titanium-based coatings is examined. Microstructural and mechanical characterisation and biological tests carried on the coatings manufactured the sequential application of CS and TO ...