Browsing by Author "Guler, Onur"

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Determination of Selective Laser Melting Process Parameters of Tungsten Carbide Powders Coated with Nickel Via Electroless Plating for Improved Interface Properties
(Elsevier Sci Ltd, 2024) Erguder, T. Oguzhan; Guler, Onur; Yildiz, Fatih
Tungsten carbide powders are commonly used at various industrial applications due to their high hardness. However, these powders may exhibit low binding and processing challenges without a binder. Therefore, various binding methods such as electroless Ni coating are used to hold WC powders together, increase their processability and improve the mechanical properties of the final product. Electroless Ni plating plays an important role in the use of WC powders, especially in processes such as selective laser melting. The structural, tribological, and mechanical properties of parts manufactured by SLM method are significantly influenced by the parameters employed in the process. Hence, optimizing process variables is essential to unlock the full potential of this advanced manufacturing technique. The main objective of this study was to identify the optimum process parameters for the SLM method of WC-Ni composite powders, which were prepared by coating WC powder materials with electroless Ni. Experimental investigations focused on analyzing the laser power, scanning speed, and hatch spacing parameters. The effects of these parameters on the mechanical and tribological properties of WCNi composite material were investigated using microhardness tester, tribometer device, optical microscope, 3D optical profilometer and scanning electron microscope. Eventually, it was determined that the manufacturing parameters employed in the SLM method had a significant impact on relative density, microstructure, surface roughness, hardness, and tribological properties. Samples exhibited a relative density of nearly 99%, and the highest observed hardness value was 1962 HV. This article supports a specialized SLM manufacturing process developed specifically to enhance durability and performance across a broad spectrum of industrial applications through interface improvement and the optimization of manufacturing parameters.
Development of Cutting Tools with Selective Laser Melting from Electroless Nickel-Coated Tungsten Carbide Powder Material
(Elsevier Sci Ltd, 2025) Erguder, Tevfik Oguzhan; Yildiz, Fatih; Guler, Onur; Sevim, Murat Ibrahim; Varol, Temel
This study was on whether cemented carbide tools could be produced using cheaper and more readily available Ni binder instead of expensive Co binder using selective laser melting, which is a new generation production method that can be easily produced in the desired design without losing scrap. The study determined the optimum laser manufacturing parameters for the production of Ni coated WC powder by electroless deposition using the selective laser melting (SLM) method and produced turning inserts with those parameters. Production of SLM-based turning inserts, including Ni-coated WC powder (WC-Ni), encountered some problems due to lack of binder. Pure Ni powders were added to Ni-coated WC powders (WC-Ni + Ni) to improve bonding which increased relative density, reduced surface roughness and resulted in similar to 95 % reduced wear rate. For optimum SLM conditions, the microhardness value was measured as 1879 +/- 130 HV0.3. The surfaces of the turning inserts produced by SLM were then ground. TiN coating was applied and the microhardness after coating was as 2002 +/- 174 HV0.3. After turning, the TiN-coated SLM insert had the lowest surface wear and performed very close to the conventionally manufactured insert.
The Effect of Selective Laser Melting Process on the Microstructure, Density, and Electrical Conductivity of Silver-Coated Copper Cores
(Springer, 2021) Varol, Temel; Hacisalihoglu, Ilyas; Kaya, Gurkan; Guler, Onur; Yildiz, Fatih; Aksa, Huseyin Can; Akcay, Serhatcan Berk
In this study, compact materials were fabricated by selective laser melting (SLM) method using copper-silver core-shell particles obtained by electroless coating method. The effect of SLM parameters such as laser power, scanning speed and hatch spacing on the important properties such as microstructure, density and electrical conductivity of compacts produced from core-shell particles was investigated. This study significantly contributes to the fact that the parameters used in the fabrication of copper-silver-based materials with the SLM method directly affect the properties of the compacts. The results showed that the silver shell thickness obtained on the core of copper powders by electroless plating method varied between 1 and 3 mu m and was distributed homogeneously. It was also found that the highest apparent density value among all samples was obtained above about 99% from the sample where 100 W power, 250 mm/s scanning speed and 45% hatch spacing values were used. In addition the highest electrical conductivity value was obtained for these conditions.
Effects of Fabrication Parameters and Post-Processing Treatments on the Mechanical and Tribological Behavior of Surface-Enhanced Copper Based Materials by Selective Laser Melting
(Elsevier Science Sa, 2022) Aksa, Huseyin Can; Hacisalihoglu, Ilyas; Yildiz, Fatih; Varol, Temel; Guler, Onur; Kaya, Gurkan; Akcay, Serhatcan Berk
Selective laser melting (SLM), which is an advanced manufacturing method developed in recent years, produces parts with complex shapes and critical dimensions using metallic powder and laser beam. In this study, copper based conductive materials with silver networks were fabricated by electroless silver coating and SLM. The effects of laser power, scanning speed, hatch spacing, build orientation and post treatments on the mechanical and tribological properties of SLM compacts manufactured from core-shell particles were investigated. After the mechanical tests, higher stress and elongation values were obtained in the sample positioned horizontally on the build platform with a laser power of 100 W, scanning speed of 250 mm/s and hatch spacing value of 45%. After that SLM process, the post-processes were applied to the samples and the physical and mechanical properties improved significantly. The highest density value was obtained by the rolling process at 900 ?, and an increase of approximately 35.6% was obtained compared to the sample without post-processing. The lowest wear rate among all samples was obtained in the hot-pressing process at 750 ?.
Microstructure and Wear Characterization of Al2O3 Reinforced Silver Coated Copper Matrix Composites by Electroless Plating and Hot Pressing Methods
(Elsevier, 2021) Guler, Onur; Varol, Temel; Alver, Umit; Kaya, Gurkan; Yildiz, Fatih
Copper-based composites are frequently used in areas such as contacts, contactors, switches etc. where electrical conductivity and tribological properties play a critical. In this work, the microstructure, electrical and wear properties of silver plated copper powder matrix and Al2O3 reinforced composites fabricated by electroless silver plating (ESP) and hot pressing were investigated. Copper powders with different morphologies fabricated by mechanical milling (MM) were used as matrix while different Al2O3 contents (0.5 %, 1 %, 2 %, 3 % and 5 wt. %) were used as reinforcement materials for the production of composites. The results showed that the ESP layer on milled copper powders for 2 h was quite uniform and the Al2O3 distribution was better in these composites than others. The highest hardness value (similar to 125 HB) and the lowest wear rate (1.5E-04 mm(3)/Nm) were observed in composites including silver plated copper matrix powders and Al2O3 (3 wt. %). Although the electrical conductivity values decrease with increasing Al2O3 ratio for all composites, the decrease in electrical conductivity was only up to about 86 %IACS in composites where the highest hardness value was obtained. Besides, the dominant wear mechanism was abrasive wear with grooves and scratches while the lowest wear scar width (about 557 mu m) was observed in these composites.