Surface modification process performed on steels by electrolytic plasma technology

SUMMARYKey Words: Electrolytic Plasma, Surface Modification, Wear, HardnessIn this thesis, an attempt has been made to develop the surface properties of conventional AISI 1040, AISI 4140, EU 1.2333 and AISI 316 L steels using electrolytic plasma technic. During study, the electrolytic plasma technology is one of the innovative technologies that have been investigated extensively at both of academic and industrial levels. After optimization of electrolytic plasma technology, surface of AISI 1040, AISI 4140, EU 1.2333 and AISI 316L steel has modified. It is observed that layer thickness and structure change with different parameter settings using optical microscopy. Also, transformation of modification layer and grain structure was investigated by using scanning electron microscopy with attached energy dispersive spectrometry (SEM-EDS).XRD results revealed that Fe2O3, Fe3O4, FeO phases were found in the modified surfaces. According to micro-hardness test results, it is observed that the value of micro-hardness of the samples changes with different distance and parameter. While the value of micro-hardness of the samples was found approximately 180HV without modification treatment, this value was raised up to 950 HV within very short time from 12 to 36 second after the treatment. Furthermore, the amount of macro-hardness on the surface of the samples was increased from 10 HRC to approximately 60 HRC. Dry sliding wear tests were performed using a linear wear machine. The wear tests were carried out at the sliding speed of 0.1 ms-1 using applied load of 5N, 10N, 20N and 30N for various distances (180, 360, 540 and 720 m). The wear results have shown that wear resistance of modified samples increased approximately five times, while friction coefficient decreased slightly. Furthermore, in this study, the utilization of electrolytic plasma treatment in the industry discusses and compares with conventional treatments.Also, using different electrolytic solutions, electrolytic plasma diffusion treatment was performed on polished 316 L stainless steel substrates. The electrolytes were chosen from inorganic salts for their soluble diffusion elements such as O, N and B. The first electrolyte was consisting H2N-CO-NH2, the second one was NH4NO3 and the last one was H3BO3. The plasma diffusion duration was chosen in the range of 5 sec. to 30 min. Dry sliding wear tests were performed using 1N and 3N applied load for 100 m and 1200 m distance. The wear results have shown that wear resistance of diffused samples increased, while friction coefficient decreased.Key Words: Electrolytic Plasma, Surface Modification, Wear, Hardness