Browsing by Author "Buytoz S."

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Effect of sintering temperature on electrical and microstructure properties of hot pressed Cu-TiC composites
(2014-01-01) Islak S.; Kir D.; Buytoz S.
In this study, Cu-TiC composites were successfully produced using hot pressing method. Cu-TiC powder mixtures were hot-pressed for 4 min at 600, 700 and 800 °C under an applied pressure of 50 MPa. Phase composition and microstructure of the composites hot pressed at different temperatures were characterized by X-ray diffraction, scanning electron microscope, and optic microscope techniques. Microstructure studies revealed that TiC particles were distributed uniformly in the Cu matrix. With the increasing sintering temperature, hardness of composites changed between 64.5 HV0.1 and 85.2 HV0.1. The highest electrical conductivity for Cu-10 wt.% TiC composites was obtained for the sintering temperature of 800 °C, with approximately 68.1% IACS.
Effect of the TiC content on microstructure and thermal properties of Cu-TiC composites prepared by powder metallurgy
(2014-01-01) Buytoz S.; Dagdelen F.; Islak S.; Kok M.; Kir D.; Ercan E.
Copper matrix with an individual addition of TiC particles was prepared by means of powder metallurgy and hot pressing process, and the effect of TiC addition on microstructure, thermal properties, and electrical conductivity of Cu-TiC composites was investigated. The TiC quantity was changed as 1, 3, 5, 10, and 15 Cu (in mass%), and Cu-TiC powder mixtures were hot-pressed for 4 min at 700 °C under an applied pressure of 50 MPa. Microstructure studies revealed that TiC particles were distributed uniformly in the Cu matrix. Thermal Analysis result showed that there were two exothermic peaks and with rising TiC rate, oxidation amount of Cu composite decreased. With the increasing addition of TiC, hardness of composites changed between 58.6 HV0.1 and 87.8 HV 0.1. The highest electrical conductivity for Cu-TiC composites was obtained in the Cu-1 mass% TiC composite, with approximately 81.2 % IACS. © 2014 Akadémiai Kiadó, Budapest, Hungary.
Effect on microstructure of TiO2 rate in Al2O3-TiO2 composite coating produced using plasma spray method
(2012-01-01) Islak S.; Buytoz S.; Ersoz E.; Orhan N.; Stokes J.; Hashmi M.S.; Somunkiran I.; Tosun N.
In this study, Al2O3-TiO2 composite coatings were thermally sprayed on the SAE 1040 steel using atmospheric plasma spray (APS) process of mixed different rates micron-sized TiO2 and micron-sized Al2O3 powders. The effects of TiO2 addition on the microstructure, phase compositions and microhardness of the coatings were investigated by using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffractometry (XRD) and microhardness tester. The results show that the Al2O3-TiO2 composite coatings consists of both fully melted regions and partially melted regions, and the fully melted region has a lamellar-like structure. Phase transformations from mainly stable a-Al2O3 and anatase-TiO2 in the powders to predominant rnetastable y-Al2O3, rutile-TiO2 and Al2TiO5 phase in the Al2O3-TiO2 composite coatings were observed. It was determined that the pore content decreased with the increased in the TiO2 powder rate. The microhardness of the coating layers was 3-4.5 times higher than substrate material. The average microhardness values of the coatings were found to reach 650-860 HV.
Effects of TiC content on transverse rupture strength (TRS) of Cu-TiC composites produced using powder metallurgy (PM) technique
(2015-01-01) Islak S.; Buytoz S.; Eski
Cu-TiC composites have been produced by powder metallurgy technique. Mixtures of Cu-TiC powders corresponding to weight fractions of 1, 3, 5, 10 and 15 wt.% TiC were hot-pressed for 4 min at 700 °C under an applied pressure of 50 MPa. The transverse rupture strength (TRS) of the composites was evaluated by a three-point bending test. SEM were used to analyze the resulting fracture surfaces from the bending test. The TRS decreased rapidly in the 0-5 wt.% TiC contents, while it decreased slowly in the 5-15 wt.% TiC contents. SEM results showed that with the increase in the addition of titanium carbide to copper matrix, pores and gaps were present in the structure.
Microstructural and Wear Characteristics of High Velocity Oxygen Fuel (HVOF) Sprayed NiCrBSi-SiC Composite Coating on SAE 1030 Steel
(2013-01-01) Buytoz S.; Ulutan M.; Islak S.; Kurt B.; Nuri Çelik O.
In this paper, wear properties of NiCrBSi-SiC coatings were investigated using the ball-on-disk wear test. In experimental study, NiCrBSi-SiC powders were sprayed using a high-velocity oxygen fuel technique on an SAE 1030 steel substrate. Powder mixtures with different weight mixing ratios, NiCrBSi + 10 wt% SiC, NiCrBSi + 20 wt% SiC and NiCrBSi + 40 wt% SiC coatings were prepared. The deposited coatings are compared in terms of their phase composition, microstructure and hardness. It is proved that the degree of mixing of the NiCrBSi and SiC components in the powder has a massive effect on the phase composition, microstructure and hardness of the coatings. Wear tests were conducted on both the uncoated and coated substrates at same normal load, speed, and wear distance. It has been determined that the coated substrates exhibit a very good tribological performance in comparison to the uncoated substrate. The increase in the adhesive wear resistance provided by the coating has been attributed to the presence of a large amount of dispersed Ni and Cr carbide and/or borides in the Ni matrix. © 2013 The Author(s).
Microstructural development on AISI 1060 steel by FeW/B4C composite coating produced by using tungsten inert gas (TIG) process
(2012-08-01) Islak S.; Buytoz S.; Karagöz M.
This study discusses the effects of B4C addition on the morphologies of primary carbides and eutectic colonies in FeW weld-surfacing alloys. Results reveal that a series of FeW weld-surfacing alloys with different B4C contents are successfully fabricated onto AISI 1060 steel by using tungsten inert gas (TIG) arc welding. SEM observations show that the obtained coating sheet has a smooth and uniform surface, as well as a metallurgical combination with the AISI 1060 steel substrate without cracks and pores at the interface. Fe23(C,B)6, Fe3(C,B), FeW2B2 and FeW3C boride and carbides are determined in the microstructure. The microhardness values of the coating results show a difference depending on the rate of B4C and coating conditions. The maximum microhardness value of the coating is about 1095 HV.
Microstructure and wear properties of FeW-SiC based composite coating produced with tungsten inert gas (TIG) surfacing method
(2011-01-01) Islak S.; Eski O.; Buytoz S.
In this study, SiC reinforced and FeW based metal matrix composite (MMC) was produced on substrate of AISI 304 stainless steel using tungsten inert gas (TIG) surfacing process. In order to examine the effect of SiC on microstructure, hardness and abrasive wear properties inside FeW matrix, SiC was changed by ratios of 10, 25, and 50% by weight. Phase compound and microstructure of coating layers were examined using X-ray diffractometer (XRD) and scanning electron microscope (SEM). Wear behaviours of samples were evaluated using pin-on disc sliding wear tests. It was found that Fe2C, Cr7C3, W2C carbide and Fe2Si, CrSi2 silica were formed in the microstructure. The studies conducted concluded that FeW-25 wt. % SiC composite coating was the most appropriate combination in terms of hardness and wear performance.
Microstructure and Wear Properties of Hot-Pressed NiCrBSi/TiC Composite Materials
(2020-09-01) Islak S.; Ulutan M.; Buytoz S.
Abstract: In this study, TiC-reinforced NiCrBSi matrix composite materials were produced using the hot pressing powder metallurgy (PM) technique. The effect of the addition of titanium carbide to NiCrBSi powder in different proportions (5, 10, and 20 wt %) on the microstructure, hardness, relative density, and wear properties of composites was investigated experimentally. NiCrBSi–TiC composites were produced for 10 min at 1000°C with an applied pressure of 45 MPa using a vacuum-assisted automatic hot-pressing machine. The wear behaviors of the composites were compared through dry sliding wear tests. Wear rates and coefficient of friction (COF) values were observed of composites. In addition, the main wear mechanisms are investigated by using SEM and EDS analyses of the worn surfaces. The wear rates of the composites were decreased by increasing the TiC content.
Microstructure properties of HVOF-sprayed NiCrBSi/WCCo-based composite coatings on AISI 1040 steel
(2013-01-01) Islak S.; Buytoz S.
NiCrBSi/WCCo-based composite coatings were produced on the surface of AISI 1040 steel using high velocity oxygen fuel (HVOF) thermal spraying technique. In the coatings produced, the WCCo quantity added to the NiCrBSi was chosen as 10, 30 and 50 wt. % percentages. The coatings were compared in terms of their phase composition, microstructure, and hardness. Phase composition and microstructure of the coatings were characterised using X-ray diffraction and scanning electron microscopy. The results indicated that the as-prepared NiCrBSi/WCCo-based composite coatings were mainly composed of γ-Ni, WC, W2C, Cr23C6, Cr7C3, CrB2, CrSi, and Co phases. Microhardness values of coating layer varied according to the addition of the powder. The highest microhardness value of the coating was measured as 1300 HV0.2.