Laser power influence on Raman spectra of ZnO(Co) nanoparticles
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To get CaTiO3catalyst with high photocatalytic properties,the effect of calcination conditions,on the photocatalytic activity of CaTiO3 was investigated.The calcination conditions included heating rate of calcination precursors,calcination temperature,calcination time and cooling rate of calcination products,The catalyst was synthesized by solid-state reaction method with Ca(NO3)2and TiO(OH)2as raw materials and NaOH as mineralizer.The physical properties of the catalyst were characterized using XRD and SEM.The experimental results showed that the activity increased until reached a maximum,and then decreased with the increasing heating rate of calcination precursors;the photocatalytic activity decreased drastically with the fast cooling rate of calcination products.Moreover,the optimal values of calcination temperature and calcination time were obtained.As a result,the CaTiO3catalysts with high photocatalytic activity can be obtained under an optimized calcination conditions after loading CoO(0.2 wt%)co-catalyst.
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Abstract GH5188 high-temperature alloy specimens were fabricated by selective laser melting (SLM) and influencing laws of laser power, laser velocity and laser energy density on density of specimens were researched. The results shows that along with the laser energy density increases from 73.02 J/mm 3 to 88.18 J/mm 3 , porosity in specimens decrease and relative density increases from 98.86% to 99.75%. However, as the laser energy density increase further, the density begins to decrease continuously. The main causes that effects relatively density including: the powder is not fused at low energy density, as well as the powder splash and gasification at higher energy density. Neither inadequate nor excessive laser energy density is conducive to improvement of density of specimens. As the increase of laser velocity and laser power, density of specimens increases firstly and then decreases. The variation trend of relative density is similar with that of laser energy density and there are reasonable ranges of laser velocity and laser power. However, influencing laws of laser velocity and laser power on density of specimens are different.
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Selective Laser Melting
Energy density
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In order to improve the activation effect of deactivation catalysts, calcination of V2O5-WO3-MoO3/TiO2 catalysts were investigated. The experimental results demonstrate that calcination time have an effect for recovering the activity of V2O5-WO3-MoO3/TiO2 catalyst. Calcination not only ensures the better mechanical strength and integrity of the catalyst, but also plays an important role in the denigration activity of the catalyst. However, the particles of the catalyst surface enlarged with the increase of the calcination temperature. The suitable calcination time can improve the denigration efficiency and increase the mechanical strength of the catalyst. In addition, the calcination time mainly affects the formation of MoO3. These findings can provide reference for the activation of SCR-Den Ox catalyst.
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Calcination rectorite(CREC) was obtained using the rectorite from Hubei Zhongxiang Mine.And setting the white degree and the residual sulfur content as the indices,the calcination conditions of rectorite were systematically seeked.Then CREC was characterized and thermally analyzed by XRD,SEM and TG-DTA,etc.The results suggested the optimum calcination condition was that the material granularity was less than 0.050 mm,the calcination temperature was 850 ℃,the rising temperature time was 4 h,the holding temperature time was 4 h.
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We calcined six kinds of limestone from various localities up to 900, 1000, 1100, 1200, 1300 and 1400°C with or without NaCl, and observed the growth of CaO crystals in their thin sections. The CaO crystals occurring in the specimens calcined with NaCl are, as usual, better grown than those without NaCl, and it is more evident at lower temperature calcination. In the case of higher temperature calcination, the formers are hardly over-burnt.With regard to the limestones, those of cryptcrystalline make finer CaO crystals. Especially it is evident at higher temperature calcination. This may show to have larger range for optimum calcination, that is easy to work with.
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Atmospheric temperature range
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Abstract In selective laser melting (SLM) the variation of process parameters significantly impacts the resulting workpiece characteristics. In this study, AISI 316L was manufactured by SLM with varying laser power, layer thickness, and hatch spacing. Contrary to most studies, the input energy density was kept constant for all variations by adjusting the scanning speed. The varied parameters were evaluated at two different input energy densities. The investigations reveal that a constant energy density with varying laser parameters results into considerable differences of the workpieces’ roughness, density, and microhardness. The density and the microhardness of the manufactured components can be improved by selecting appropriate parameters of the laser power, the layer thickness, and the hatch spacing. For this reason, the input energy density alone is no indicator for the resulting workpiece characteristics, but rather the ratio of scanning speed, layer thickness, or hatch spacing to laser power. Furthermore, it was found that the microhardness of an additively manufactured material correlates with its relative density. In the parameter study presented in this paper, relative densities of the additively manufactured workpieces of up to 99.9% were achieved.
Selective Laser Melting
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Mg was extracted from boron mud through calcining method. The technological process is that the boron mud was calcined at 700 °C for 3 h then uniformly mixed with (NH 4 ) 2 SO 4 in proportion and calcined. The reaction process was studied by TG-DTA and XRD, which is that MgO in calcined boron mud reacts with (NH 4 ) 2 SO 4 to produce (NH 4 ) 2 Mg 2 (SO 4 ) 3 at low temperature, then with increasing the temperature, (NH 4 ) 2 Mg 2 (SO 4 ) 3 decomposes into MgSO 4 . The effects of calcination temperature, mol ratio of reaction substrates and calcination time on conversion rate of Mg were studied. The results indicate that the conversion rate of Mg increases with the increasing of calcination temperature first then decreases, increases with the increasing of calcination time and mol ratio of (NH 4 ) 2 SO 4 and MgO. When the calcination temperature is 500 °C, the calcination time is 3 h, the mol ratio of (NH 4 ) 2 SO 4 and MgO is 0.9:1, the conversion rate of Mg is 81.9 %.
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Power density
Microcrystalline
Pulsed Laser Deposition
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