In this research, the effect of multi-walled carbon nanotubes (MWCNTs) on the alumina/chromia (Al2O3/Cr2O3) nanocomposites has been investigated. Al2O3/Cr2O3-MWCNTs nanocomposites with variable contents of Cr2O3 and MWCNTs were fabricated using coprecipitation process and followed by spark plasma sintering. XRD analysis revealed a good crystallinity of sintered nanocomposites samples and there was only one phase presence of Al2O3-Cr2O3 solid solution. Density, Vickers microhardness, fracture toughness and fracture strength have been measured in the sintered samples. The results show that the relative density, microhardness and fracture strength of nanocomposites are significantly improved at low contents of Cr2O3 and MWCNTs. The increase of MWCNT’s content in the nanocomposites has adversely affected due to increasing the tangle and interaction of MWCNTs with each other, which leads to agglomeration in the nanocomposites. Increasing of Cr2O3 content in nanocomposites increases formation of Al2O3-Cr2O3 solid solution that actually requires the high sintering temperature to achieve good densification. The fracture toughness of Al2O3/Cr2O3-MWCNTs nanocomposites was enhanced by increasing the carbon nanotube content.
عملية صناعة واتخاذ القرار في السياسة الخارجية للرئيس جورج والكر بوش
The Decision Making Process (DMP) is considered the vital from the point of view intellectuals. That is because of its effect on performance and the level of productivity of the workers in any organization. In the educational organization in particular, it plays a pivotal role in the technical, managerial and supervision fields. In addition to the productivity there was a great effect on the moral of the workers in all part of the organization, self respect and the problem solving approach to all work difficulties and challenges. All that leads to a better working environment where goals are achieved in a collaborative effort.
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... Show MoreCorncob is an agricultural biomass waste that was widely investigated as an adsorbent of contaminants after transforming it into activated carbon. In this research carbonization and chemical activation processes were achieved to synthesize corncob-activated carbon (CAC). Many pretreatment steps including crushing, grinding, and drying to obtain corncob powder were performed before the carbonization step. The carbonization of corncob powder has occurred in the absence of air at a temperature of 500 °C. The chemical activation was accomplished by using HCl as an acidic activation agent. Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), X-ray diffraction (XRD), and Brunauer–Emmett–Teller (BET) facilitate
... Show MoreABSTRACT The isolation and characterization of (27) isolate of extreme halophilic bacteria was performed ninteen isolate belonged to the genus Halobacterium which included Hb.halobium. Hb. salinarium, Hb. volcanii. Growth curve and generation time in logarthmic phase was measured and found to be (12.8hr±0.32), (11.2hr±0.2), (9.8hr±0.87), respectivaly. Effect of various concentrations of NaCl, KCI, NH4Cl and MgSO4.7H2O was studied, NaCl was essential for the rod shape rapid growth Rat and pigmentation. Less than 1% concentration caused lysis of bacteria. Yeast extract was the best carbone source as compared with glucose and casamino acid.
Abstract
The aim of this paper is to model and optimize the fatigue life and hardness of medium carbon steel CK35 subjected to dynamic buckling. Different ranges of shot peening time (STP) and critical points of slenderness ratio which is between the long and intermediate columns, as input factors, were used to obtain their influences on the fatigue life and hardness, as main responses. Experimental measurements of shot peening time and buckling were taken and analyzed using (DESIGN EXPERT 8) experimental design software which was used for modeling and optimization purposes. Mathematical models of responses were obtained and analyzed by ANOVA variance to verify the adequacy of the models. The resul
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