Research Information System
Thesis Type: Postgraduate
Institution Of The Thesis: Ataturk University, Fen Bilimleri Enstitüsü, Makine Mühendisliği Anabilim Dalı, Turkey
Approval Date: 2019
Thesis Language: Turkish
Student: Yeşim Seçer
Supervisor: Halim Kovacı
Abstract:
Metallic materials used in many engineering applications are exposed to undesirable effects such as wear, fatigue and corrosion throughout their lifetime. Different processes are applied to reduce these effects to which metallic materials are exposed and to extend their service life. One of the most preferred of these processes is surface treatments. Surface pattern/ texture design is an important part of surface engineering, especially in terms of improving tribological properties. The aim of this study is to investigate the effects of different surface patterns / textures on tribological properties of metallic materials. For this purpose, samples with different surface patterns (hexagonal, scattered, ellipse, square, triangular and new model) were produced by using 316L stainless steel powder together with selective laser melting (SLM) production method, which is one of the additive manufacturing methods. The production was carried out in two stages: Group 1 samples were produced to determine the optimum value of field density and group 2 samples were produced to observe the effect of the shape of the geometric pattern on tribological properties. In addition, plasma nitriding process was applied to the samples produced as group 2 and the surface patterns and the synergistic effect of this plasma nitriding process on the mechanical properties were investigated. XRD, SEM, three dimensional profilometer and micro hardness tester were used to examine the morphological, structural and mechanical properties of the samples. The samples were subjected to a circular (pin-on-disk) wear test in a dry and simulated body fluid (SBF) medium. The ellipse geometric pattern showed the best tribological feature due to the absence of sharp corners and the ability to trap wear in the geometric pattern in dry experiments, and that the positive net hydrodynamic benefit was obtained in the liquid environment. The increase in hardness as a result of plasma nitriding resulted in a reduction in wear rate and the lowest wear rate after plasma nitriding was achieved for all sample groups.