In this study, lateritic nickel ore from Manisa-Çaldağ, Turkey was subjected to sulfation roasting. Experimental parameters were as follows, acid concentration (10-90 wt.%), roasting temperature (200-900°C) and time (15-90 min). Effect of sodium sulfate addition (1-9 wt.%) on dissolutions of nickel and cobalt was also investigated. It was concluded that iron dissolution has increased with increased acid concentration. Dissolutions of nickel and cobalt increased with increasing roasting temperature and time below the decomposition temperature of related metal sulfates. It was concluded that addition of sodium sulfate in roasting stage has no significant effect on dissolutions of related metals.
In this study, the wear behaviors of curvilinear involute-profile gears, which were intended to be used in the industry and manufactured successfully, have been identified. For this purpose, the gears have been manufactured and attached to a FZG gear analysis bench; then, they were compared with spur gears by examining the behaviors of curvilinear involute-profile gears under different loads at different speeds, certain cycles. As a result of these analyses conducted, it has been determined that the wear behaviors of these newly manufactured curvilinear involute-profile gears are better than the behaviors of the spur gears, and in the increasing number of cycles, the curvilinear involute-profile gears had less wear than the spur gears have.
Smithsonite, ZnCO₃, from Zamantı-Kayseri, Turkey, was subjected to high-energy milling. X-ray diffraction analysis was performed to study amorphisation in the structure and the alterations of bands in the structure were investigated by Fourier transform infrared spectroscopy. Characterization of milled smithsonite by X-ray diffraction analysis has shown that disappearance, decrease and/or shifting of the patterns occurred with mechanical activation, which means that amorphisation was taking place. Amorphisation was also demonstrated by Fourier transform infrared spectroscopy analysis, where shifting of band centers was observed.
We studied cracks in two different In_{x}Ga_{1-x}As/GaAs(001) multi-quantum-well structures by electron microscopy. Transmission and scanning electron microscopy analyses of the sample-1 revealed that the epilayers associated with cracks. Detailed experimental works on the cracks were carried out by conventional and high-resolution electron microscopy. It was found that the epilayers were very effective on stopping the cracks in sample-1. Many dislocations were observed around the cracks and cracks tips. SEM images showed that the cracks formed an orthogonal set array accompanying with slits and pits. However, there were not observed any cracks in the sample-2.
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