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61.
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
62.
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
63.
Dinesh K. Patel Bathula Vishwanadh Vasanthakumaran Sudarsan Shailendra K. Kulshreshtha 《Journal of the American Ceramic Society》2013,96(12):3857-3861
BaTiO3 and BaSnO3 samples doped with Eu3+ ions were prepared using glycine‐nitrate gel combustion method. Relative intensities and line shapes of magnetic dipole allowed 5D0 → 7F1 and electric dipole allowed 5D0 → 7F2 transitions of Eu3+ from the hosts, BaTiO3 and BaSnO3, are significantly different. Based on detailed structural investigations, it is confirmed that synthesizedBaTiO3 sample is tetragonal with no center of symmetry around Ba2+ ions. Unlike this BaSnO3 is cubic with centrosymmetric Ba2+ site. From X‐ray diffraction and experimentally obtained Judd–Ofelt parameters (Ω2 and Ω4 values), it is confirmed that in BaTiO3 there is a decrease in the average Ba–O and Ba–Ba distances compared with that in BaSnO3. This leads to higher Eu–O bond polarizability and adds to the distortion in its environment around Eu3+ in BaTiO3:Eu compared with BaSnO3:Eu. This is responsible for the observed difference in the luminescence properties. 相似文献
64.
Sarbjit Kaur Dinesh K. Shetty Raymond A. Cutler 《Journal of the American Ceramic Society》2007,90(11):3554-3558
The concept of a crack-stability map is developed by considering the interaction between the crack-driving force and the rising crack-growth resistance of a toughened ceramic. The map plots normalized transition crack length as function of the ratio of the crack-initiation fracture toughness and the plateau toughness to delineate regimes of stable and unstable crack growth. The plot is used to analyze R curves and fracture stresses of a transformation-toughened Ce-TZP/Al2 O3 . It is shown that the fracture stress and the small scatter measured for this ceramic are consistent with its R- curve behavior, which enables stable growth of surface cracks from flaws (pores and second-phase particles), leading to a flaw-insensitive ceramic. 相似文献
65.
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
66.
This paper presents the steady state behaviour and maintenance planning of the desulphurization process in the fertilizer industry. The process consists of four subsystems, A, B, C and D in series with three states; good, reduced and failed. One standby unit is provided for each pump. Taking constant failure and repair rates for each subsystem, mathematical modelling is done using the Chapman-Kolmogorov birth-death process. An expression for steady state availability is given. Based on the data available from a medium sized ammonia production process, the behaviour of each working unit in the process has been analysed. The computed results are discussed with the concerned plant personnel which is helpful to the management for implementing any future plan regarding design modification of the system/processes. 相似文献
67.
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
68.
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
69.
Artak Heboyan Mikayel Manrikyan Muhammad Sohail Zafar Dinesh Rokaya Ruzan Nushikyan Izabella Vardanyan Anna Vardanyan Zohaib Khurshid 《International journal of molecular sciences》2021,22(11)
The present in vivo study determined the microbiological counts of the gingival crevicular fluid (GCF) among patients with fixed dental prostheses fabricated using three different techniques. A total of 129 subjects were divided into three study groups: first, cobalt-chrome-based, metal-ceramic prostheses fabricated by the conventional method (MC, n = 35); the second group consisted of cobalt-chrome-based, metal-ceramic prostheses fabricated by the computer-aided design and computer-aided manufacturing (CAD/CAM) technique (CC-MC, n = 35); the third group comprised zirconia-based ceramic prostheses fabricated using the CAD/CAM technique (CC-Zr, n = 35). The control consisted of 24 patients using prostheses fabricated with either MC, CC-MC, or CC-Zr. The GCF was obtained from the subjects before treatment, and 6 and 12 months after the prosthetic treatment. Bacteriological and bacterioscopic analysis of the GCF was performed to analyze the patients’ GCF. The data were analyzed using SPSS V20 (IBM Company, Chicago, IL, USA). The number of microorganisms of the gingival crevicular fluid in all groups at 12 months of prosthetic treatment reduced dramatically compared with the data obtained before prosthetic treatment. Inflammatory processes in the periodontium occurred slowly in the case of zirconium oxide-based ceramic constructions due to their biocompatibility with the mucous membranes and tissues of the oral cavity as well as a reduced risk of dental biofilm formation. This should be considered by dentists and prosthodontists when choosing restoration materials for subjects with periodontal pathology. 相似文献
70.
Dinesh C. Agrawal R. Gopalakrishnan Dipankar Chakravorty 《Journal of the American Ceramic Society》1989,72(6):912-915
Two cubic phases of differing compositions and lattice parameters and a monoclinic phase are found in samples of zirconia with 8 mol% calcia and 4 to 10 mol% titania. Increasing amounts of titania reduce the amounts of the cubic phases. The monoclinic phase dissolves small amounts (∼1 mol%) of calcia and up to 4.7 mol% titania; these amounts for the cubic phases are much larger. The cubic lattices contract linearly with increasing amounts of titaia and a contraction in the monoclinic lattice is also evident. 相似文献