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An approach to optimize the processing parameters to get superior ridging resistance and mechanical properties in commercial production of 430 ferritic stainless steel has been studied. Attention was also paid to improve productivity and energy saving without hampering the surface and mechanical property aspects of the material. Hot rolled coils annealed by slow cooling under insulated cover exhibit better ridging resistance than bell annealing treatment with a minor decrease in ductility. Soaking temperature prior to hot rolling has a significant effect on ridging resistance.
Yttrium iron garnet, Y3Fe5O12 (YIG) powders were synthesized by mechanochemical processing (MCP) from
different iron sources (FeO, Fe2O3 and Fe3O4)
mixed with Y2O3, followed by a heat treatment. The aim of
this work is to demonstrate that MCP followed by annealing at very low
temperatures (as compared with the classic solid state reaction) can induce the
formation of nanostructured YIG. The effect of iron source on final structure
was also studied. X-ray diffraction (XRD) and scanning electron microscopy
(SEM) were used to characterize the synthesized powders. The precursors
mixed in a stoichiometric ratio to obtain YIG were milled at room temperature
in a shaker mixer mill with a ball:powder weight ratio of 10:1. A partial
synthesis of YIG was achieved after 9 h of milling time by using the three
sources of iron; however, a significant fraction of the product was the perovskite
YFeO3. The largest yield of YIG was obtained by using FeO. In all
cases a single garnet phase could only be completely obtained after an
annealing process at 900?C, around 400?C lower than the typical temperatures to
prepare the material by solid state reaction. An analysis of the microstrain
and lattice parameters associated with peak displacements is discussed.
Cobalt nanoparticles on the surface of highly oriented pyrolytic graphite have been studied by atomic force microscopy. Thermal annealing in ultrahigh vacuum was used to change the size of cobalt nanoparticles and their surface distribution. The effect of two key parameters, annealing time and temperature, on the size and the surface distribution of nanoparticles has been studied. The dependence of the particle size on these parameters has been obtained. It has been shown that the main mechanism of the nanoparticle growth is Ostwald ripening.