Mechanical Engineering / Makina Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/4129
Browse
5 results
Search Results
Now showing 1 - 5 of 5
Article Citation - WoS: 15Citation - Scopus: 14Development of Electrically Conductive and Anisotropic Gel-Coat Systems Using Cnts(Elsevier Ltd., 2013) İnce Yardımcı, Atike; Tanoğlu, Metin; Selamet, YusufElectrical conductivity of an unsaturated thermoset polyester based gel-coat system containing 0.05 wt.% of carbon nanotubes (CNTs) was investigated. The CNTs used were synthesized by chemical vapor deposition method by methane decomposition and Raman characterization showed that they were mostly single walled and high quality. To disperse CNTs in the gel-coat resin, 3-roll milling technique was used. It was found that as the CNTs are added to gel-coat system, resistivity value decreases significantly while neat gel-coat showed a high resistivity. By the application of an AC electrical field during curing process, it was attempted to align CNTs in the gel-coat resin and an electrically anisotropic polymer was obtained. © 2012 Elsevier B.V. All rights reserved.Article Citation - WoS: 8Citation - Scopus: 12A Microstructural Study of Surface Hydration on a Magnesia Refractory(Elsevier Ltd., 2010) Sütçü, Mücahit; Akkurt, Sedat; Okur, SalihHydration of the surface of a periclase refractory was studied in a controlled humidity atmosphere (92% relative humidity) at 26 °C for up to 92 h. The effect of humidity on the specimens was examined using a scanning probe microscope (SPM) and a scanning electron microscope (SEM), which showed that the degree of hydration was noticeably less in the intergranular bond phase compared to the periclase crystallites. The SPM study indicated significant growth of hydrates on the refractory grain surface. Growth rate of the hydrate layer was least on (0 0 1) orientation, higher for the (1 0 3) orientation, and highest for the (1 0 1) oriented grain. The rate of loss of refractory phases by hydration on a (1 0 1) oriented grain was 4.53 nm/h. This material loss may be insignificant for a bulk brick, but is a serious threat for a magnesia castable consisting of fine magnesia powder due to large surface area exposed to humidity or water itself. © 2010 Elsevier Ltd and Techna Group S.r.l. All rights reserved.Article Citation - WoS: 15Citation - Scopus: 17Influence of Crystallographic Orientation on Hydration of Mgo Single Crystals(Elsevier Ltd., 2009) Sütçü, Mücahit; Akkurt, Sedat; Okur, SalihThis study has been performed in order to find out the influence of crystallographic orientation on hydration of MgO single crystal substrates with (1 0 0)-, (1 1 0)-, and (1 1 1)-orientations. The samples were left in a hydration chamber with an 88% relative humidity for 18 h at room temperature. The effect of humidity on the samples was examined by scanning probe microscope (SPM) and scanning electron microscope (SEM) which showed that the degree of hydration was noticeably influenced by the crystallographic orientation. It was found that the MgO with (1 1 1)-orientation has the highest tendency to hydrate than the other orientations. Second most affected sample was (1 1 0) crystal. Loss of MgO on the surface by hydration is most severe when the crystal is oriented in (1 1 1) plane with the maximum hydrate layer thickness of 174 nm after 18 h of exposure.Article Citation - WoS: 3Citation - Scopus: 3Thermostable Tensoresistors of Co Doped Gasb-Fega1.3 Eutectic Composites(Elsevier Ltd., 2008) Rahimov, R. N.; Khalilova, A. A.; Arasly, D. H.; Aliyev, M. I.; Tanoğlu, Metin; Özyüzer, LütfiThe microstructure and tensoresistive properties of GaSb-FeGa1.3 eutectic composites doped with 0.1% Co have been investigated. It was found that the Co impurity atoms mainly accumulate in the metallic inclusions. The length of the inclusions in GaSb-FeGa1.3〈Co〉 was measured to be about half of those in undoped GaSb-FeGa1.3 eutectics. The tensometric characteristics of gauges based on GaSb-FeGa1.3〈Co〉 have been found to be more thermostable than undoped samples. © 2008 Elsevier B.V. All rights reserved.Conference Object Citation - WoS: 39Citation - Scopus: 48Temperature Dependence of Electrical Conductivity in Double-Wall and Multi-Wall Carbon Nanotube/Polyester Nanocomposites(Springer Verlag, 2007) Şimşek, Yılmaz; Özyüzer, Lütfi; Seyhan, Abdullah Tuğrul; Tanoğlu, Metin; Schulte, KarlThe aim of this study is to investigate temperature dependence of electrical conductivity of carbon nanotube (CNT)/polyester nanocomposites from room temperature to 77 K using four-point probe test method. To produce nanocomposites, various types and amounts of CNTs (0.1, 0.3 and 0.5 wt.%) were dispersed via 3-roll mill technique within a specially formulized resin blend of thermoset polyesters. CNTs used in the study include multi walled carbon nanotubes (MWCNT) and double-walled carbon nanotubes (DWCNT) with and without amine functional groups (-NH2). It was observed that the incorporation of carbon nanotubes into resin blend yields electrically percolating networks and electrical conductivity of the resulting nanocomposites increases with increasing amount of nanotubes. However, nanocomposites containing amino functionalized carbon nanotubes exhibit relatively lower electrical conductivity compared to those with non-functionalized carbon nanotubes. To get better interpretation of the mechanism leading to conductive network via CNTs with and without amine functional groups, the experimental results were fitted to fluctuation-induced tunneling through the barriers between the metallic regions model. It was found that the results are in good agreement with prediction of proposed model.