ABSTRACTIndia does not possess any soluble potassium (K) sources but an abundant resource of alumino-silicate rock such as feldspar is available. In the present work, an attempt has been made to unlock the potassium values from feldspar sample by mechanical milling, roasting and leaching and delineating the underlying mineral phase changes. CaCl2 was found to be effective flux for K release with valuable by-products such as quartz and anorthite. The roasting kinetics follows the product layer diffusion model with an activation energy of 49.50 kJ/mol. It is found that the planetary ball milling has a significant effect on enhancing K-dissolution. With the combination of different treatments, it is possible to recover more than 95% K from feldspar. 相似文献
Selenium, along with mercury and halides, represents one of the most volatile trace metallic emissions from coal‐fired combustors and utility boilers. This study investigates the potential of activated carbon in capturing gas phase selenium species in the low temperature range (125°C to 250°C) and elucidates the mechanism of interaction between selenium species and activated carbon. Selenium dioxide is chosen as the representative selenium species and experimental investigations are carried out in a differential bed reactor to illustrate the mechanism of SeO2 and carbon Interaction, Activated carbons with different structural properties are studied as adsorbents for selenium dioxide capture at low temperature. The capture mechanism is found to involve both physical and chemical adsorption in the low temperature range. At 125°C, about 1.5 wt% of selenium is captured at equillbrium. Carbon surface analyses and XPS studies confirm the presence of both elemental and oxide forms of selenium on the surface suggesting partial reduction of selenium dioxide to elemental selenium at carbon surface. 相似文献
Multiple voids and cracks were generated during material processing techniques, which interact with each other and affects the service performance of piezoelectric components. This work aims to study the behavior of piezoelectric components in presence of multiple cracks under thermo-electro-mechanical loading environment. Extended finite element method has been implemented to model geometrical discontinuities with crack interaction phenomenon. In this work, thermo-electro- mechanical problem has been decoupled into thermal and electro-elastic problems. Temperature distribution has been obtained by solving heat conduction equation and then used as an input to the electro-elastic problem. In post processing phase, interaction integral method and generalized Stroh formalism were used to predict the stress intensity factors. The methodology has been implemented with in-house developed MATLAB code. Set of cases for crack interaction studies were presented using the proposed approach.
We report the effects of the thermal annealing and dopant concentration on the optical properties of Se or S-doped hydrogenated amorphous silicon thin films. The Se and S-doped a-Si:H (a-Si,Se:H and a-Si,S:H) thin films were prepared by glow discharge plasma enhanced chemical vapor deposition (GD-PECVD) on 7059 corning glass. The films were subsequently annealed in vacuum in the temperature range from 100 to 500 °C. Influence of doping and annealing was examined by means of optical transmission spectroscopy of the films in the wavelength range of 300-1100 nm taken at room temperature. The absorption coefficients and refractive indices decreased as the annealing temperature increased from 100 to 300 °C and then increased again as the annealing temperature further increased to 500 °C, while the highest bandgap was observed at 300 °C for all of the samples. For a given dopant concentration bandgap was observed to be higher in a-Si,S:H than a-Si,Se:H thin films. 相似文献
Mixture of cobalt ferrite and strontium hexaferrite nanocrystals i.e. SrFe12O19/CoFe2O4 exhibiting super paramagnetic nature were synthesized by modified flux method. The resulting precursors were heat treated
(HT) at 900 and 1200°C for 4 h in nitrogen atmosphere. During heat treatment, transformation proceeds as instantaneous rate
of nucleation and three dimensional growth with activation energy of 135.835 kJ/mole. The hysteresis loops showed a hike in
saturation magnetization from 1.045 to 84.362 emu/g with an increase in HT temperature. The ‘as synthesized’ particles have
size in the range of 10–20 nm with spherical shape. Further, these spherical shape particles tend to change their morphology
to hexagonal plates with increase in HT temperatures. The relative complex permittivity and permeability of the composite
powder are investigated. The minimum reflection loss of the composite powder reaches to −27.6 dB at 10.8 GHz which suits its
application in RADAR absorbing materials. 相似文献