Browsing by Author "Guler, Ebru Saraloglu"

Now showing 1 - 8 of 8

The effects of coating conditions on the friction and corrosion resistance of carbon steel
(2020) Guler, Ebru Saraloglu; Buyukluoglu, Berkay; 0000-0002-3732-1268; AAD-1956-2020
Coatings are applied by using several methods to ensure low friction with high corrosion and wear resistance, particularly in gear applications. The friction and corrosion performance of black-phosphate-coated carbon steel at different temperatures and operating times were studied in this study. Moreover, comparison of the black phosphate coating and traditional manganese coating was conducted in terms of friction coefficient and corrosion resistance. The optimum temperature and time for black-phosphate-coated steels were 70 degrees C and 20 min, respectively. The coating temperature showed a significant effect, whereas time displayed a minor effect on friction, but both of the results favor a lower energy cost. The average friction coefficient of black-phosphate-coated sample was calculated as half of the one obtained by manganese phosphate coating under the same coating conditions.
Enhancing Carbon Fiber Reinforced Aluminum Laminates With Cellulose Paper Interlayers: Experimental Characterization Of Tensile, Flexural, And Interlaminar Fracture Toughness
(Başkent Üniversitesi Mühendislik Fakültesi, 2024-03-30) Ustun, Tugay; Guler, Ebru Saraloglu
The mechanical properties of fiber metal laminates (FML) are influenced by several various factors. Interface adhesion plays a particularly crucial role in interlaminar strength. Enhancing the interlaminar strength of carbon fiber reinforced aluminum laminate (CARALL) composites present a persistent challenge due to inherent weaknesses between metal and composite elements. Therefore, this study focuses on improving the interlaminar performance of CARALL composites by introducing cellulose paper interlayer at the metal/composite interface. The cellulose paper interlayer offers the advantage of being cost-effective and sustainable. Cellulose paper-interleaved CARALL composites were fabricated by vacuum bagging method and exhibited noteworthy improvements in mechanical properties. Comparative analysis with pristine samples revealed substantial enhancements, including a 15% increase in tensile strength, a remarkable 42% improvement in flexural strength, and a significant enhancement in mode-I fracture toughness by 65%. Furthermore, the cellulose paper interleaving played a crucial role in stabilizing fracture formation at the fiber-matrix interface, with mode II fracture toughness witnessing a 3% increase. Visual examination revealed the underlying toughening processes occurring in the interfacial area. This innovative approach of interleaving laminated composites with cellulose paper emerges as a sustainable and effective strategy, demonstrating the potential to fortify and toughen the interlaminar zones of CARALL composites. [GRAPHICS]
Investigation of the Tribological Behaviour of Electrocodeposited Ni-Mos2 Composite Coatings
(2017) Guler, Ebru Saraloglu; Konca, Erkan; Karakaya, Ishak; 0000-0002-3732-1268; 0000-0001-8943-091X; 0000-0002-4646-6207; AAD-1956-2020; N-6390-2017
Composite electroplating of solid lubricants in a metal matrix is an effective way to lower coefficient of friction (COF) and improve wear resistance of surfaces in sliding contact. In this work, Ni-MoS2 composite coatings were deposited on AISI 304 stainless steel substrates by electroplating from Watts bath containing suspended MoS2 particles and their tribological behaviour was studied. The effects of MoS2 particle concentration (5, 10 and 30 g/l), MoS2 particle size (1.440 and 5.156 mu m), pH (2, 3 and 4), current density (3.8, 4.8 and 5.8 A/dm(2)) and the surfactant (sodium lignosulfonate, SLS) concentration (0.3 and 1 g/l) on the tribological behaviour were investigated using a ball-on-disc tribometer at ambient conditions. Lower current density, smaller particle size and higher concentration of MoS2 decreased COF. While increasing the surfactant concentration decreased the COF, its friction lowering effect was much more pronounced at relatively lower concentrations of MoS2 in the electrolyte.
Maximizing Electromagnetic Interference Shielding Through Carbon Fiber Plating with Nickel: A Parameter-Based Approach
(Başkent Üniversitesi Mühendislik Fakültesi, 2024-03-02) Guler, Ebru Saraloglu; Irgin, Dilara
Electromagnetic interference (EMI) poses significant challenges to modern electronic systems and devices, garnering increasing attention as technology advances. EMI shielding methods have emerged as a crucial solution to mitigate the associated problems. The primary objective of shielding is to deflect or absorb electromagnetic waves emitted from a source. Traditionally, metals have been used for shielding materials due to their excellent conductivity. However, the high weight and cost of metals have spurred research into alternative materials. Carbon fiber materials have gained prominence in recent years due to their exceptional mechanical and electrical properties. These materials find diverse applications across industries, including defense, automotive, aviation and space. One approach to enhance the conductivity of carbon fibers is the application of metallic coatings. This study investigates the electromagnetic shielding properties of nickel-coated and uncoated polyacrylonitrile-based (PAN-based) carbon fiber fabrics at the frequency ranges of "300-1500 MHz," "2170-3300 MHz" and "3300-4900 MHz" offering valuable insights into their applications. Additionally, microstructure analysis and energy-dispersive X-ray spectroscopy (EDS) were conducted. The results demonstrated that nickel coating significantly improves EMI shielding effectiveness within the specified frequency ranges. Notably, the Ni-electroplated sample, treated at a current density of 8.7 A/dm2 for 30 min, exhibited the highest shielding effectiveness at "300-1500 MHz." Moreover, the most noteworthy performance was observed in electroless nickel-coated carbon and nickel-electroplated (at a current density of 7.3 A/dm2 for 45 min) fiber specimens within the "2170-3300 MHz" and "3300-4900 MHz" frequency ranges. Absorption and reflection values were calculated to clarify the underlying mechanisms governing EMI shielding behavior. The findings reveal that absorption mechanisms predominantly contribute to the observed EMI shielding behavior.
Mechanical and Tribological Evaluation of Zinc/Zinc-Zirconia Composite Coatings on Ti6Al4V Alloys
(PROTECTION OF METALS AND PHYSICAL CHEMISTRY OF SURFACES, 2024-06) Kustepe, Kaan; Guler, Ebru Saraloglu
Zinc plays a vital role in supporting prenatal and postnatal growth and development. Moreover, for over a century, zinc and its alloys have been extensively used as coatings to enhance the surface properties of various metals. However, zinc coatings alone exhibit limited resistance to frictional loads, which necessitates their combination with ceramic particles. Particle reinforced composite coatings have emerged as a promising solution to further enhance the mechanical and tribological properties of metals. This study focuses on the electroplating of zinc and zinc reinforced with ZrO2 onto Ti6Al4V alloys, exploring the impact of coating parameters on the thickness and mechanical behavior of the coatings. Through a comprehensive analysis, including electron microscope examination (SEM) of the microstructure, tribometer measurements, scratch resistance test, adhesion strength analysis and atomic force microscope (AFM) assessment of surface roughness, the performance of the coated Ti6Al4V alloys is investigated. The results demonstrate that the Zn-ZrO2 composite coated specimen exhibits the lowest minimum wear rate. Additionally, an increase in the incorporation of ZrO2 particles correlates with a decrease in the wear rate.
Optimisation of Cutting Parameters for Minimizing Carbon Emission and Maximising Cutting Quality in Turning Process
(2018) Ic, Yusuf Tansel; Guler, Ebru Saraloglu; Cabbaroglu, Ceren; Yuksel, Ezgi Dilan; Saglam, Huri Maide; https://orcid.org/0000-0002-3732-1268; AAD-1956-2020
Modern manufacturing systems are faced with the challenge of reducing the carbon emission related to manufacturing technologies. Machining centres consume large amounts of energy and as a consequence; carbon emissions are generated owing to this consumption. This paper presents a design of experiment work related to the optimisation of machining factors in the turning process of aluminium alloys. Carbon emission and surface quality were concurrently optimised. A set of experimental scenarios was set using a Box-Behnken design and the response surface methodology was applied to get the regression model for the carbon emission and surface roughness during turning process. The relationship between factors and the responses (carbon emission and surface quality) was investigated using surface plots. Furthermore, the desirability function method using the Response Optimizer tool in MINITAB and goal programming methodology was used to obtain the values of the parameters that achieved minimum surface roughness and a minimum quantity of carbon emission.
Optimization Of Processing Parameters For Minimum Residual Stress And Maximum Wear Resistance During Gas Nitration Of 4140 Steel
(2022) Tuzuner, Sibel; Metin, Ali Baran; Guler, Ebru Saraloglu; Sahin, Tugce
Several surface treatments has been applied to the 4140 specimens which are exposed to frictional conditions like eears in order to increase the wear resistance and hardness. Nitration is a common method to improve the hardness 0( the surfaces. However, the parameters must be chosen wisely. The parameters of temperature, time, flow rate during nitration of SA I 4140 steels were optimized in this study. The ranges for the parameters are selected as 470 degrees C - 520 degrees C - 570 degrees C. 7h - 9h - 12h and 6m(3)/h - 7.5m(3)/h - 9m(3)/h for temperature, time and flow rate respectively. Residual stress, hardness and wear resistance were measured for the specific experiments together with microscopic observations. The nitration process of the threaded part was completed using the optimized parameters. As a result of the study, it was observed that the maximum wear resistance and minimum residual stress values was obtained by the parameters of 470 degrees C, 12h, 9m(3)/h.
Reducing Uncertainty in a Type J Thermocouple Calibration Process
(2019) Ic, Yusuf Tansel; Guler, Ebru Saraloglu; Cakir, Zeynep Erbil; AAI-1081-2020
Thermocouples are used in many manufacturing processes in order to read the actual temperature of the product. Calibration of thermocouples is critical wherever they are used. However, the uncertainties must be considered and the factors that affect the uncertainty value must be regarded during the calibration of thermocouples. In this study, design of experiments by Taguchi method has been performed in order to reduce uncertainty during calibration of Type J thermocouples. Within the scope of this study, parameters which are assumed to effect temperature oscillations have been determined and necessary experiments have been conducted using temperature well and proper inserts. The parameters were selected as insert material, thermocouple immersion depth and type. It can be concluded that the immersion type has the highest effect, whereas immersion depth has minimum effect on the uncertainty value. As a result of the study, a value for parameters which results in best possible temperature uniformity of the well is achieved.