Formation of Cr (C, B, N) based coatings on the steel surface using the termo-reactive diffusion (trd) method and investigation of their properties

Steel materials have been the most important helpers of human beings in a wide range of sectors such as automobile, defense, aviation, maritime and construction. Although the expectations from steels vary according to the usage sectors, some problems may arise depending on the usage conditions of the steels. These problems are mostly caused by repetitive loads, the effects of chemical reactions and mechanical interactions. In this academic study, it is aimed to form Cr (C, B, N) based coating layers by using thermo reactive diffusion method on steel surfaces made of AISI D2 tool steel. This thesis study consists of two stages. In the first stage, nitriding processes and boronizing processes of metallographically prepared materials were carried out. In the second stage, nitrided steel surfaces, boronized steel surfaces and samples of AISI D2 steel were subjected to the coating process by thermo reactive diffusion method in the coating bath containing ferro-chromium, alumina, sal ammoniac and naphthalene. Characterization processes have been carried out to reveal coating efficiencies. The properties of Cr (C, B, N) based coating layers by boronizing and nitriding obtained on the surface of AISI D2 steel material have been analyzed in a wide frame. While the microstructure and elemental analysis of the obtained coatings were examined by optical microscope, scanning electron microscope and elemental structure analysis, x-ray diffraction (XRD) assay was used for phase analysis. The mechanical functions of the obtained Cr (C, B, N) based coating layers were revealed by micro-vickers hardness measurement method and also the corrosion behavior of the coating layers was investigated in the simulated body fluid (SBF) environment.