Papers by Author: G. Stergioudis

Abstract: The paper aims to compare the hardness and corrosion behavior of carburized and borided Iron-Based Austenitic Steels (IBAS) which were treated at the same temperature and time under vacuum conditions. Boronizing was performed by pack cementation in Ekabor II powder and carburization was carried out by annealing under vacuum conditions using glucose as a carburizing medium. Both boronizing and carburizing procedures were performed at 900°C for 3h. The characterization of the treated materials was assessed by using X-Ray Diffraction (XRD) analysis, optical observations, Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray Spectroscopy (EDS) measurements and micro-Vickers hardness tests. Potentiodynamic polarization curves were also used to determine electrochemical characteristics such as the corrosion potential (mV), corrosion current density (μΑ/cm²) and corrosion rate (μm/year). The results showed that borided samples with a single phase layer, exclusively Fe₂B strongly toothed, exhibited better hardness behavior towards carburized samples but lesser corrosion resistance instead.

Abstract: In this research, efforts were made to study the modification of microstructure of pure Ni matrices. Modification was attempted using glucose as carburizing medium under a control of heat treatment conditions. Nickel plates were carburized under vacuum conditions at 380°C and 650°C for 3 hours. In order to determine the parameters of the carburizing, thermal properties of glucose along with the thermochemical behavior were examined by Thermogravimetric Analysis (TGA) and Differential Thermal Analysis (DTA). The characterization of the microstructure of the carburized specimens was investigated by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Energy-Dispersive X-ray Spectroscopy (EDS). For analyzing the effect of temperature treatment on corrosion resistance, electrochemical corrosion tests were conducted. It was observed that the polarization curves for carburized samples at 380°C were shifted to lower corrosion current densities. Consequently, lower corrosion rates were achieved for these samples preventing the formation of extensive corrosion over their surfaces comparing with carburized Nickel substrates at 650°C.