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1.
This paper presents the importance and usage of natural zeolites, which was recently recognized in the industry. Therefore, the grinding properties of natural zeolite were studied with the emphasis on a kinetic study in a ball mill. The experimental mill employed was laboratory sized, 200 mm diameter, 191 mm length, providing a total mill volume of 6000 cm3, with a total mass of 5.62 kg of steel balls of 25 mm diameter with a charge of 20% of the mill volume and with a rotation speed of 76 rpm. The breakage parameters were determined by using single sized feed fractions of ?850+600 μm, ?600+425 μm, and ?425+300 μm for the zeolite samples. The Si (specific rate of breakage) and Bi, j (primary breakage distribution) values were obtained for those feed size fractions in order to predict the product size distributions by simulation for comparison to the experimental data. From the experimental results, Si values increased as the feed sizes became coarser, i.e., the highest Si value was 0.85 min?1 for ?850+600 μm, while the lowest Si value was 0.65 min?1 for ?425+300 μm feed ground in the mill. The Bi, j values obtained for the zeolite sample were γ=0.84, ?=0.61, and β=4.25. The breakage parameters obtained showed that the zeolite is broken faster than quartz and slower than calcite and barite in terms of the aT values reported previously at the same experimental conditions. The simulations of the product size distributions of zeolite were in good agreement with the experimental data using a standard ball mill simulation program. The slowing‐down effect was also seen in the mill after 4 min. of grinding. 相似文献
2.
3.
Karla J. Moreno Miroslaw Maczka Ulises Amador 《Journal of solid state chemistry》2006,179(12):3805-3813
The structural and microstructural characteristics of metastable Gd2(Ti1−yZry)2O7 powders prepared by mechanical milling have been studied by a combination of XRD and Raman spectroscopy. Irrespective of their Zr content, as-prepared powder phases present an anion-deficient fluorite-type of structure as opposed to the pyrochlore equilibrium configuration obtained for the same solid solution by other synthetic routes. These fluorites are stable versus thermal activation, at least up to temperatures of 800 °C. For the Ti-rich compositions, thermal treatments at higher temperatures facilitate the rearrangement of the cation and anion substructures and the relaxation of mechanochemically induced defects whereas for compositions with high Zr content, the fluorite crystal structure is retained even at temperatures as high as 1200 °C. Interestingly enough, transient pyrochlores showing a very unusual cation distribution were observed during the thermally induced defect-recovery process. 相似文献
4.
X.P. Zhu Tomiyuki Yukawa Hisayuki Suematsu Kiyoshi Yatsui Y. Inoue 《Applied Surface Science》2006,252(16):5776-5782
X-ray photoelectron spectroscopy (XPS) is used to probe oxidation states of Si species in particles deposited using a pulsed ion-beam evaporation method. The effects of He ambient gas, ion beam intensity and post-treatments on the oxides composition and oxygen content have been studied. It is found that presence of He ambient gas led to a profound oxidation of Si species as compared to that prepared in vacuum at the same ion-beam ablation energy, i.e. both increase of SiO2 component and oxygen concentration in the oxides coverage. The deposition in He also resulted in an increase of oxygen concentration even under lower ablation intensity, but a higher Si suboxides concentration. It is revealed that the reaction between Si and O was controlled by the ion beam intensity (temperature of Si plasma) and the gas ambient (collision probability of Si and O species). The difference in structure of oxide layers for samples obtained under various conditions is discussed based on the results of XPS analyses. 相似文献
5.
Based on scalar diffraction theory, 8-phase-level 256×256 elements diffractive microlens array with element dimension of 50×33 μm2 have been fabricated on the back-side of PtSi(3~5 μm) infrared CCD. The measurement results indicated that the ratio of the signal-to-noise of the infrared CCD with microlens was increased by a factor of 2.8. 相似文献
6.
Wieczorek-Ciurowa K. Gamrat K. Paryło M. Shirokov Ju. G. 《Journal of Thermal Analysis and Calorimetry》2002,70(1):165-172
The physical mixtures of hydroxocarbonates of Cu and Ni with aluminium were activated using a laboratory planetary mill. The
chemical reactions and alloy formations as the effects of grinding were followed by the phase analysis of solid products based
on the thermogravimetry and X-ray diffractometry. Experimental evidence indicates that the nature of reactions and products
of mechanical activation was dependent on the amount of aluminium and time of grinding.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
7.
8.
机械球磨与反应烧结合成Sr2CeO4发光体的研究 总被引:10,自引:0,他引:10
Sr2CeO4 phosphor was synthesized by mechanical milling and reactive sintering in this work. The solid state reaction of SrCO3and CeO2 (2∶1) started at about 850 ℃ and completed at 1 000 ℃ for about 4 h. Two types of formation mechanism of Sr2CeO4 were proposed. When the starting powder mixture was fired above 1 000 ℃, the unstable intermediate phase SrCeO3was developed, which then reacted with SrCO3to form the final product Sr2CeO4, however, SrCO3and CeO2 converted directly to Sr2CeO4 at a lower temperature. The XRD results showed the crystal structure of Sr2CeO4 was orthorhombic. The emission spectra displayed a broad band with maximum at about 465 nm. The mechanical milling of starting power mixture and the sintering temperature had no effect on this emission spectra. 相似文献
9.
Josef Janča 《Mikrochimica acta》1994,112(5-6):197-215
The primary field forces can generate spatially oriented gradient of the effective property of a continuum or pseudo-continuum fluid (carrier liquid). When this gradient is coupled with the action of a secondary field of identical or different nature the isoperichoric focused zones of the dispersed species can appear. Consequently, they can be separated according to differences responding to the property gradient of the carrier liquid. This concept can be applied under static (non-flow) conditions in thin layer focusing as well as under dynamic conditions with the elution due to the carrier liquid flow in focusing field-flow fractionation. The gradient established by the action of the primary field and the concentration distribution of the isoperichoric focused zone formed by the coupled effect of the gradient and of the primary or secondary field are described theoretically. The rigorous relationship describing the shape of the focused zone is compared with the approximate solutions. The performances of the proposed principle were evaluated by model calculations. Potential experimental configurations considering the implementation of the static and dynamic conditions are discussed. The generalized isoperichoric focusing theory can be applied to describe the particular processes operating in analytical and preparative focusing separations of the particles of various, but especially of biological origin. 相似文献
10.
Philip Wormald Kristina Wickholm Per Tomas Larsson Tommy Iversen 《Cellulose (London, England)》1996,3(1):141-152
An investigation into the effects of mechanical treatment and hydration on the order of cellulose substrates (microcrystalline cellulose and Cladophora cellulose) was performed by the use of ball milling followed by cyclic wetting and drying. The results, monitored by13C-CP/MAS NMR-spectroscopy, were evaluated by calculation of the crystallinity indices and principal component analysis of the NMR data acquired. The results showed that a large part of the disorder induced by the mechanical treatment of cellulose by ball milling is reversible and reordering upon hydration leads to the cellulose I form initially present. The C4 signals corresponding to the reversibly disordered cellulose chains are observed in the amorphous region between 79 and 86 ppm in the13C-CP/MAS NMR-spectra together with signals from cellulose chains on the surface of ordered regions. The peak cluster which contains the C2, C3 and C5 ring carbons can be divided into two specific spectral regions; one between 74 and 77 ppm largely originates from ring carbons within disordered cellulose structures, and one between 70 and 74 ppm contains larger contributions from ordered cellulose. The behaviour of the celluloses upon milling is in accordance with a concept of ordered cellulose fibrils containing amorphous cellulose mainly as surface layers and induced reversible lattice distortions. 相似文献