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61.
Pramod S. Dobal Rasmi R. Das Ram S. Katiyar Dinesh C. Agrawal 《Journal of the American Ceramic Society》2000,83(8):1953-1956
Powder compacts of TiO2 and ZrO2 were prepared from their suspensions in water at different pH values, and micro-Raman spectroscopy was used to reveal the degree of mixing in each of them, with different sizes of the focused laser spot. The change in laser intensity and particle-size distributions led to a slight variation in the average composition, as determined using three different probe sizes. The Raman-estimated volume fractions of each constituent indicated that the aqueous suspensions in which the powders were well dispersed produced the most-uniform mixing. Powders that were flocculated in suspensions before mixing also resulted in a good mixture. The most-nonuniform mixing was observed when, in the individual suspensions, one of the constituents was dispersed and the other was flocculated. These results indicated that Raman spectroscopy can be useful for the rapid determination of the degree of mixing in powder mixtures. 相似文献
62.
Effects of carbon nanofibers on cell morphology, thermal conductivity and crush strength of carbon foam 总被引:1,自引:0,他引:1
The effects of low volume fractions of carbon nanofibers on the structure, thermal conductivity and crush strength of carbon foam were examined. Bulk density of the foam increased linearly with the fiber fraction reflecting the morphological changes in the cells. Thermal conductivity increased at low fiber fractions, but dropped at higher fiber fractions. Crush strength increased linearly with fiber fraction for short length fibers, but decreased for the longer length fibers. Scanning electron microscopy, petrography, and X-ray diffraction illustrated the complex effects of the carbon nanofibers on the foam. Available models for thermal conductivity and crush strength have been extended to accommodate these effects incorporating cell structure and morphology (macroeffect), presence of fibers (microeffect), and graphite crystal d-spacing (nanoeffect). This research has shown that the nanofibers have a complex role in the macro, micro, and nanoproperties of the composite foam. 相似文献
63.
Ghanshyam S. Chauhan Baljit Singh Sandeep Chauhan Surya K. Dhiman Dinesh Kumar 《应用聚合物科学杂志》2006,100(2):1522-1530
In continuation to our earlier work to use bioresource for developing alternate materials for use at the interface of biotechnology and polymer science, we have utilized pine needles as a renewable stock of cellulose to synthesize graft copolymers of vinyl imidazole. Kinetics of N‐VIm by simultaneous γ‐irradiation method has been investigated as a function of total dose, monomer concentration, and amount of water. Effect of water–methanol solvent composition on graft yields and polymerization kinetics has also been studied at the optimum grafting conditions of the total dose and monomer concentration. Effect of some additives such as ZnCl2, Mohr salt, tetramethylethylene diamine, potassium persulfate, ammonium persulfate as grafting accelerators and promoters has also been studied. Graft copolymers have been characterized by elemental analysis, FTIR, and swelling studies. The graft copolymers have been used as supports for metal ions sorption, enzyme immobilization, and as potential biomimicking catalysts. Sorption behavior of Fe2+ ions and Cu2+ ions and the immobilization of bovine serum albumin and protease as a function of graft yield has been reported. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1522–1530, 2006 相似文献
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66.
The present work is an attempt to improve some of the mechanical properties of cemented tungsten carbide (WC) cutting tool by subjecting it to different post treatments. The different post treatments that are tried out to the tungsten carbide-cobalt (WC-Co) inserts are a) controlled cryogenic treatment, b) heating and forced air cooling and c) heating and quenching in oil bath. The response of WC-Co inserts to such different post treatments has been evaluated in terms of microhardness, microstructural changes, scanning electron microscope (SEM) micrograph and Co metal phase changes through XRD. The experimental result indicate a remarkable response to all the above mentioned post treatments and the analysis of the same are presented in this paper. 相似文献
67.
Avijit Mondal Anish Upadhyaya Dinesh Agrawal 《International Journal of Refractory Metals and Hard Materials》2010
Microwave heating is recognized for its various advantages, such as time and energy saving, very rapid heating rates, considerably reduced processing cycle time and temperature, fine microstructures and improved properties. The present paper investigates the feasibility of consolidating tungsten powders through microwave sintering. A comparative analysis has also been attempted between the sintering response of pure tungsten powder compact in a microwave and conventional furnace. 相似文献
68.
Dinesh Kumar Misra Sung Woo Sohn Won Tae Kim Do Hyang Kim 《Science and Technology of Advanced Materials》2008,9(4)
The plastic deformation of Ti45Zr16Be20Cu10Ni9 bulk metallic glass has been investigated by nanoindentation performed with loads ranging from 10 to 200 mN in a wide range of loading rates. The plastic flow in the alloy exhibited conspicuous serrations at low loading rates. The serrations, however, became less prominent as the rate of indentation increased. Atomic force microscopy showed a significant pile-up of materials around the indents, indicating that a highly localized plastic deformation occurred under nanoindentation. The possible mechanism governing the plastic deformation in bulk metallic glass specimens is tentatively discussed in terms of strain-induced free volume. 相似文献
69.
This paper discusses stochastic analysis of the ash handling system in a thermal power plant. The system consists of four subsystems Ai, Bj, C and Dk in series, with three possible states: good, reduced and failed. Failure and repair rates for each subsystem are taken to be constants. Using a probabilistic approach, the differential equations are generated and the expression for steady state availability is computed. Taking data from the thermal power plant, situated in North India, the behaviour of each working unit is analysed. Problems and remedies with appropriate maintenance schedules have been discussed. The results are discussed with the plant personnel and are helpful to the management in predicting the behaviour of each operating unit, so that timely decisions can be taken for maintaining the system in upstate for a long duration. 相似文献
70.
Characterization of influence zones of simulated droughts and floods of water bodies in a floodplain
S. Dinesh 《Computers & Geosciences》2008,34(12):1791-1797
During flooding processes, randomly situated water bodies of varying sizes and shapes in a floodplain tend to self-organize. At high degrees of flooding intensity, water bodies contact together to form influence zones, which indicate the self-organized criticality of the flooding of water bodies. The characterization of water bodies and their influence zones provides useful insight into the geomorphic properties of floodplain terrains. In this paper, characterization of the influence zones of simulated droughts and floods of water bodies in a floodplain is performed. First, drought and flood simulations are implemented by performing morphological erosion and dilation, respectively, on water bodies using square kernels of increasing sizes. The level of droughting/flooding is indicated by the kernel size. The average areas of the influence zones of the generated simulated droughts and floods of water bodies are computed. It is observed that as the droughting level increases from 1 to 5, the average area of the influence zones of water bodies reduces due to the shrinking of water bodies. As the droughting level increases from 5 to 15, the average area of the influence zones of water bodies increases due the vanishing of small water bodies. Flooding causes an increase in the average area of the influence zones of water bodies due to the merging of adjacent water bodies. A power law relationship is observed between the average area of the influence zones of the simulated droughts/floods and the level of droughting/flooding. The scaling exponent of this power law, which is named as a fractal dimension, indicates the rate of change of average area of the influence zones of simulated droughts/floods of water bodies in a floodplain over varying levels of droughting/flooding. 相似文献