Browsing by Author "Calik, A."

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Citation - WoS: 9
Citation - Scopus: 11
Boriding Kinetics and Mechanical Properties of Borided Commercial-Purity Nickel
(Natl inst Science Communication-niscair, 2017) Uçar, Nuri; Calik, A.; Ucar, N.; Delikanli, K.; Carkci, M.; Karakas, S.; Bankacılık ve Finans; 03.01. Bankacılık ve Finans; 03. İktisadi ve İdari Birimler Fakültesi; 01. Çankaya Üniversitesi
Kinetics of boride layer growth and tensile behaviour in bonded commercial-purity nickel was investigated. Bonding was carried out in a solid medium consisting of Ekabor-II powders at 1173, 1223 and 1273 K for periods of 3, 5 and 8 h. Scanning electron microscopy (SEM) and optical microscopy showed column morphology in the boride layer. X-ray diffraction (XRD) analyses indicated that the boride layer formed on the surface consisted mainly of Ni2B, with precipitates of Ni6Si2B. A parabolic relationship between layer thickness and processing temperature was observed. The obtained results showed that although the boride layer thickness increased with increasing boriding temperature and time, boriding parameters had no significant effect on the hardness of the boride layer or the matrix. Tensile properties were negatively influenced by the bonding treatment; both yield and tensile strength values decreased due to the presence of the hard yet brittle surface coating. In addition, the growth kinetics of boride layers was also analysed. The results showed a nearly parabolic relationship between the layer thickness and the process temperature, with activation energy of 47.3 kJ mol(-1).
Diffusion Kinetics of Binary Ti-Ni Shape Memory Alloys
(Polish Acad Sciences inst Physics, 2017) Dogan, S.; Ozdemir, A. F.; Karakas, S.; Calik, A.; Ucar, N.; 48915; 03.01. Bankacılık ve Finans; 03. İktisadi ve İdari Birimler Fakültesi; 01. Çankaya Üniversitesi
In this work, the boriding of binary Ti-Ni shape memory alloys was carried out in a solid medium at 1173 and 1273 K for 2, 4, and 8 h using the powder pack method with Ekabor-Ni powders. The boride layer was characterized by optical microscopy and scanning electron microscopy. The obtained results show that boride layer thickness increases with the increasing boriding temperature and time. Depending on temperature and boride layer thickness, the diffusion process is thermally activated, with the mean value of the activation energy being close to 67 kJ/mol.
Citation - WoS: 1
Effect of Nickel Content on the Boronising Behaviour of Permalloys
(Scibulcom Ltd, 2015) Ucar, N.; Karakaş, Mustafa Serdar; Iyi, O.; Uçar, Nuri; Calik, A.; Karakas, M. S.; 48915; Malzeme Bilimi ve Mühendisliği; Bankacılık ve Finans; 06.07. Malzeme Bilimi ve Mühendisliği; 03.01. Bankacılık ve Finans; 03. İktisadi ve İdari Birimler Fakültesi; 06. Mühendislik Fakültesi; 01. Çankaya Üniversitesi
Permalloys with nickel contents ranging from 60 to 90% were boronised in a solid medium using the powder pack method. In this method, commercial Ekabor-II powders were thoroughly mixed with ferro-silicon powders to form the boronising medium. The samples were boronised in an electrical resistance furnace for 5 h at 1173 K under atmospheric pressure. The results showed that borosilicide and boride layers were formed on the surface of boronised permalloys, with average hardness of 900-1000 HV0.1. The average thickness of the multilayer coating was 90 mu m, and did not show significant change with Ni content within the range studied. The saw-tooth morphology of the boride layers were smoothened with increasing nickel content.
Citation - WoS: 5
Citation - Scopus: 5
Investigation of the Erosive Wear Resistance of Boronized Ash-Blowing Nozzles
(Polish Acad Sciences inst Physics, 2017) Calik, A.; Ozbakir, O.; Karakas, S.; Ucar, N.; 48915; 03.01. Bankacılık ve Finans; 03. İktisadi ve İdari Birimler Fakültesi; 01. Çankaya Üniversitesi
In this study, pack boronizing was applied to ash-blowing nozzles manufactured from AISI 1040 steels using Ekabor II powders as the boronizing source at a temperature of 1273 K for a duration of 8 h. Erosive wear tests of boride ash-blowing nozzles were carried out in ash delivery line of thermal reactor under actual working conditions. It was observed that erosive wear resistance of borided ash-blowing nozzles were increased 3 times as a result of the boronizing process. The improved wear resistance of the borided samples can be explained by increased surface hardness and higher work hardening.