Ersin Arslan

CHARACTERIZATION OF TiB2 COATING ADHERENCE BY A MULTI-PASS SCRATCH TESTING

TiB2 films deposited using various deposition techniques are used to increase the wear lifetime of industrial components. The performance of TiB2 films is dependent on the coating–substrate adhesion. In this study, the fatigue behavior of TiB2 films was investigated using the multi-mode scratch method. Films of TiB2 were deposited on silicon wafers and AISI M2 steel substrates at different frequencies by pulsed-dc closed field unbalanced magnetron sputtering (CFUBMS). The microstructures of the films were investigated using SEM techniques, and the hardness was measured using a microhardness tester. A multi-mode operation was used for sliding-fatigue, like multi-pass scratching in the same track at different fractions of critical load (bidirectional sliding) and a standard mode using progressive load operation. It was observed that the films deposited at low frequencies had higher adhesion strength and microhardness, and a denser microstructure.

The effect of plasma electrolytic oxidation process parameters on the tribocorrosion properties of TiO2 coatings

Abstract Despite the fact that Titanium and its alloys are materials which have excellent corrosion-resistant properties, they have poor wear and friction performance under tribological conditions. The aim of this study is to find suitable parameters for the surface treatment of Cp-Ti substrates which are used under saline environment. In this study, TiO2 coatings were grown on Cp-Ti substrates at different frequencies which are parameters of the coating process. Due to its low cost and ability to achieve high thicknesses, The Plasma Electrolytic Oxidation (PEO) method was applied to grow TiO2 coatings. The microstructures, morphology, and crystallographic structure were analyzed using SEM and XRD. Tribocorrosion properties of the coatings were investigated using a combination of the pin-on-disk wear test and potentiodynamic polarization test units. The frequency is known to have a strong impact on the PEO process. The impacts of frequency changes on the PEO coating performance were examined under a constant voltage. As result, the increase of the frequency caused smaller pores and cracks in the surface morphology of the coating and at the same time this yielded an increment on the tribocorrosion behavior of the coating.

Analysis of Tribo-corrosion Properties of MAO/DLC Coatings Using a Duplex Process on Ti6Al4V Alloys

In recent years, various technologies have been increasingly investigated for the surface modification of Ti and Ti alloys. Microarc oxidation (MAO) is one of the effective techniques to improve surface properties. However, it has some disadvantages for sliding wear applications and/or aggressive environments. In this study, the combined MAO and closed field unbalanced magnetron sputtering process was used to deposit duplex MAO/diamond-like carbon (DLC) coatings on Ti6Al4V alloy. Analysis of the microstructures, morphology, and crystallographic structure were performed by using a SEM, Raman, and XRD. The wear, corrosion, and tribo-corrosion properties of the coatings were investigated using the pin-on-disk wear test, potentiodynamic polarization test, and combining tribo-corrosion test unit, respectively. The results of this study have shown that duplex MAO/DLC coatings exhibit better wear, corrosion, and tribo-corrosion properties than the DLC or MAO monolayer on Ti6Al4V alloy substrate. MAO/DLC coatings exhibited dense structure, lower coefficient of friction and corrosion current density, and higher tribo-corrosion resistance. The results have also shown that MAO/DLC duplex coatings on Ti6Al4V substrates increased the tribo-corrosion resistance by acting as a barrier layer.

The effect of TiO2 coating on biological NiTi alloys after micro-arc oxidation treatment for corrosion resistance

NiTi alloys exhibit good properties, such as shape memory behavior, high corrosion resistant, having the closest elasticity modulus of a human bone and superior biocompatibility properties. However, the surface problems that arise during the use of this alloy limit the usage in the industry and health sector. In recent years, micro-arc oxidation method is used to improve the surface properties and increase the usage of these alloys. In this study, the TiO2 coatings were deposited on the NiTi substrates. The surface topography, morphology, crystallographic structure, and thickness of the coatings were determined using scanning electron microscopy and X-ray diffraction. The corrosion properties were investigated using potentiostat test unit in two different media such as NaCl solution and simulated body fluid. The results show that the coated samples have higher corrosion resistance than uncoated samples in the two different media.