The ultrasonic nanocrystalline surface modification (UNSM) was applied to disk specimens made of Cu-Zn alloy in order to investigate the UNSM effects under five various conditions on wear of deformation twinning. In this paper, ball-on-disk test was conducted, and the results of UNSM-treated specimens showed that surface layer dislocation density and multi-directional twins were abruptly increased, and the grain size was altered into nano scale. UNSM delivers force onto the workpiece surface 20,000 times per second with 1,000 to 4,000 contact counts per square millimeter. The UNSM technology creates nanocrystalline and deformation twinning on the workpiece surface. One of the main concepts of this study is that defined phenomena of the UNSM technology, and the results revealed that nanocrystalline and deformation twinning depth might be controlled by means of impact energy of UNSM technology. EBSD and TEM analyses showed that deformation layer was increased up to 268 microm, and initial twin density was 0.001 x 10(6) cm(-2) and increased up to 0.343 x 10(6) cm(-2). Wear volume loss was also decreased from 703 x 10(3) mm3 to 387 x 10(3) mm3. Wear behavior according to deformation depth was observed under three different combinations. This is related to deformation depth which was created by UNSM technology.
NiO/Al2O3, known as one of the most efficient oxygen carrier, has been fabricated by spray-drying method and calcinated at 1100 °C and 1300°C, and the structural characteristics are investigated using XRD, SEM, TEM and XPS. For the characterization of surface and bulk microstructure of the fabricated NiO/Al2O3oxygen carrier particle, investigated were 1) as-fabricated powders, 2) internal structure of the crumbled particles, and 3) cross-sectional specimens. The results showed that the fabricated oxygen carrier formed well distributed NiAl2O4with NiO particles of 100~500 nm via reaction keeping on the mole ratio. The oxygen carriers developed in this study showed pertinent characteristics for chemical-looping combustion, and good effect on the strength, indicating a potential for wide application in the future. The calcination at 1100 °C was good enough and as efficient as that at 1300 °C.
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