Hakan Gökmeşe

Fabrication and characterization of nanoparticle MgO/B4C composite by mechanochemical method:

In this study, nanoparticle boron carbide was produced after the reduction of boron oxide with magnesium under the presence of carbon by using mechanochemical synthesis method. During the synthesis processing, microstructure and phase transformations of powders were performed by using X-ray diffraction (XRD), Fourier-transform infrared spectrum (FT-IR), scanning electron microscope (SEM), and high-resolution transmission electron microscopy (HRTEM). At the end of 2 h, reaction products (MgO, B4C) were determined by XRD and FT-IR examinations. Nanoparticle B4C single-phase crystalline structure from the MgO/B4C composite powder mixture, which was the reaction product, was obtained by leaching process. With the increase in the synthesis period, starting material peaks diminished and Fe peak intensity became evident. After the HRTEM examinations, it was determined that synthesized B4C particles were within range of 10–200 nm especially in the activation of leaching process. Additionally, by using spot pattern analysis method, planes represented by B4C particles were calculated.

Fabrication and characterization of nanoceramic particle Al2O3/B4C composite by mechanochemical approach

ABSTRACT Al2O3/B4C ceramic phase composite structure was produced by solid-state method. Transformations of ceramic phases, micromorphology were determined by employing X-ray diffraction, FT-IR, scanning electron microscopy and transmission electron microscopy (TEM). Transformation of ceramic phases was completed in a short time (6 h). Formation of Al2O3/B4C ceramic-phase powder mixtures was specified after leaching. As a result of the increase of mechanical energy and the amount of ceramic phase, reduction in powder particle size (50–350 nm) and increase in agglomeration tendency were observed. The impurities were removed after leaching and the distribution in which the ceramic phases are effective was obtained with the TEM study.

Improvements of dry sliding wear behaviour and mechanical properties in 2014 Al alloy by age-hardening

In this study AA 2014 powder metal alloy was produced by using the vertical gas atomization method. In the post-production stage, by unidirectional pressure in the steel mould, the powders were converted into powder metal samples. The derived powder metal particles from the micro structural point were subjected to sintering process for 1 h at the temperature range of 550 and 620°C. Next, the samples were exposed to heat treatment at the temperature interval of 2 to 192 h in 500 and 600°C. For aging heat treatment, water quenching process post-solution treatment at 520˚C was applied to these samples. Afterwards, these samples were applied to aging process at 150°C on the condition of the range of 4 to 24 h, and up to 70% increase in hardness was determined. Finally, through an examination of dry fictional wear behaviours of samples processed at 550 and 600°C, oxide occurrence with increasing heat was observed to effect wear loss and wear loss was identified not to be linear as the distance raised. Key words: Wear, age-hardening, 2014 Al alloy.