SEARCH RESULT

The aim of the study is searching for the best parameters for St-37 steel surface by Electro Spark Deposition (ESD) method with using Inconel 718 alloy electrode. ESD process was carried out in different voltages (30-62 volt), different frequents (75-130 Hz) and different atmosphere (in air and in silicon oil pool). For varying electrical and ambient conditions, samples were prepared and their coating thickness (9,30 µm - 14,39 µm) and surface roughness (2,043 µm - 5,891 µm) values were measured. The coating thickness was determined higher in the air experiments. Also, thickness and roughness values were increased with the increased voltage, but there were not certain effect of the frequent on thickness and roughness. In addition, SEM images, linear and local EDX analysis, cross-sectional hardness test and XRD analysis were also obtained. It was detected that all coatings have iron-nickel based alloys and CrFe alloy were found in silicon oil pool experiments. Moreover, the cross-sectional hardness tests presented that the coating is two times harder than the steel substrate. By the SEM experiments, it was determine that coating layer had micro pores and good bonding with substrate.

International Iron & Steel Symposium
UDCS

Mustafa Safa YILMAZ Kemal Korkmaz ALİ ÇAKIR Cengiz DOGRU

Electro-spark Deposition (ESD) technique is a surface treatment process to produce hard and wear resistant coating on metallic materials [1,2]. Micro-arc Oxidation (MAO) process; also called as Plasma Electrolyte Oxidation (PEO) is a promising surface modification technique to produce a ceramic based coating on the valve metals in a suitable electrolyte [3,4]. In this study, to develop a hard and wear resistant coating on the Ti6Al4V alloy, firstly Al electrode material was deposited on the substrate by using ESD technique and then MAO process was applied in the electrolyte (NaAlO2 and KOH). In the previous work [5], the ESD process was employed in the air while the duplex coating was fabricated on the Ti6Al4V alloy by using ESD and MAO process. However, the present ESD was employed in a shielding gas (argon). Thus, the only aluminium-based phases were obtained in the ESD coating. Then, the MAO process was applied to improve phase structure and tribological properties of the aluminium alloyed. Phase structure, elemental composition, hardness and wear resistance of the duplex coating were analysed by using an X-Ray Diffractometer (XRD), Scanning Electron Microscopy (SEM), EDX, micro Vickers tester and tribometer. The results indicated that the outer layer consists of the -Al2O3 (Corundum) and - Al2O3 phases, while Al and Al3Ti phases were detected in the ESD coated layer. So, hardness and wear resistance of the duplex coating were improved with an increasing the present -Al2O3 (Corundum) phase.

International Symposium on Light Alloys and Composite Materials
UHAKS

Serhat Cıbır Metin Usta Salim Levent Aktuğ Kemal Korkmaz