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排序方式: 共有1776条查询结果,搜索用时 15 毫秒
991.
A thermomechanical process(TMP) consisting of three cycles of cold pressing at 154 MPa and liquid-phase sintering at 600 ℃ for 30 min in each cycle was applied to modify the microstructure of nanostructured Al-Zn-Mg alloy.The alloy powders were produced by mechanical alloying.Also,solid-state sintering at 550 ℃ for 90 min was done to compare the results with those obtained from the TMP.The powders and the thermomechanically(TM) processed samples were analyzed by XRD to reveal the present phases in addition to calculating the crystallite size changes by the Williamson-Hall method.Moreover,scanning electron microscope was employed to observe the morphology of the powder and the microstructures of the sintered and the TM processed samples.The results revealed that the TMP affected the microstructure noticeably as well as the microhardness by removing the continuous grain boundary porosities and uniform distribution of the intermetallic phase particles as well as obtaining a near globular microstructure after the second cycle.Also,the average grain sizes in the first and the second cycles of the TMP were lower than those of the sintered sample.Furthermore,nanocrystalline grains were stable up to the second cycle of the TMP. 相似文献
992.
Mohsen Mahmoudysepehr Vahak K. Marghussian 《Journal of the American Ceramic Society》2009,92(7):1540-1546
Zirconolite (CaZrTi2 O7 ) is a mineral that has a high containment capacity for actinides and lanthanides and is considered to be a good candidate for the immobilization of radioactive wastes. The glass–ceramic technique seems to be a very suitable and convenient method to produce zirconolite crystals by precipitating them in a specific glass matrix. In this study, development of a new zirconolite-based glass–ceramic belonging to SiO2 –PbO–CaO–ZrO2 –TiO2 –(B2 O3 –K2 O) system was investigated. The presence of PbO, together with B2 O3 and K2 O, allowed the preparation of a X-ray diffraction (XRD) amorphous glass with a relatively high concentration of ZrO2 and TiO2 , which was successfully converted to a glass–ceramic containing 34 wt% of zirconolite after heating at 770°C for 4 h. Differential thermal analysis, XRD, scanning electron microscope, and energy dispersive X-ray spectroscopy were used to determine the crystallization conditions, identify the crystallized phases, determine their compositions and quantities and observe and analyze the microstructures. The zirconolite crystals showed a platelet morphology with a monoclinic structure characterized by a =1.246 nm, b =0.7193 nm, c =1.128 nm, and β=100.508°. 相似文献
993.
Flame‐retardant polyvinylchloride (FRPVC),typically used in cable insulation and jacketing construction for multi‐purpose reactor (MPR) at Atomic Energy Authority of Egypt, as well as carbon‐black FRPVC (CB‐FRPVC) and nonflame‐retardant PVC and CB‐PVC materials produced by Egyptian Electrical Cable Company (EECC), have been irradiated up to 160 KGy, at room temperature with a 60Co gamma source. Free‐volumes and thermal stability of irradiated and nonirradiated PVC samples have been examined using positron annihilation Lifetime Spectroscopy (PALS) and thermogravimetric analysis (TGA). In addition, the mechanical properties: tensile strength and elongation at break were examined. Considerable presence of flame‐retardant and carbon black additives in CB‐FRPVC sample led to both quenching and inhibition of Ps formation. The mechanical and thermal characterization showed that irradiation of PVC samples up to 80 KGy effectively induced cross‐linking to maxima. Higher doses then after results in degradation and thus a decrease in mechanical strength. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 相似文献
994.
Zohrab Ahmadi Mohsen Ashjari Rahil Hosseini Jaefar Rahman Nia 《Journal of Inorganic and Organometallic Polymers and Materials》2009,19(3):322-327
Antibacterial ceramic consisting silver nanoparticles in TiO2 (rutile phase) particles were prepared via the chemical deposition route. Structure of synthesized ceramic was characterized
using different methods of spectroscopies including; X-ray diffraction (XRD), TEM, and scanning probe microscopy (SPM). The
results show that very fine silver particles were loaded on the titania dispersedly and also no crystalline change happened
in the TiO2 structure. In order to preparation of antibacterial composite, ceramic was compounded into polypropylene using a Hakke internal
mixer in optimized conditions. Morphology of composite was confirmed by AFM images. Finally, antibacterial activity of composite
was studied against Staphylococcus aureus. Results show that the bactericidal effect of this composite is significant and suggesting the composite to be promising
candidate for applications in fields. 相似文献
995.
996.
Achillea millefolium L. comprises several relevant species for the food, cosmetic, perfumery, and pharmaceutical industries. Gas chromatography/mass spectrometry analysis revealed borneol to be a major component of A. millefolium, with its contribution to the essential oil being 36.35%. Borneol exhibited significant lipid peroxidation inhibition and antimicrobial activity against all tested bacterial strains. In addition, borneol had the highest antioxidant activity in all conducted assays. The borneol had significantly greater radical scavenging activity than other component essential oil and the reference antioxidant Trolox. In addition, a correlation between antioxidant activity and the total phenolic content was found. The borneol significantly inhibited nitric oxide production in lipopolysaccharide-activated macrophages (an in vitro model of inflammation). These results clearly show the antimicrobial, antioxidant, and anti-inflammatory effects of the plant essential oils. 相似文献
997.
Rahnama Hassan Nikmard Mahdi Abolhasani Mohsen Osfoori Rahim Sanjarian Forough Habashi Ali Akbar 《Food science and biotechnology》2017,26(5):1437-1445
Food Science and Biotechnology - The safety of feeding transgenic potato (Solanum tuberosum), resistant to the potato tuber moth, to Wistar rats was examined from an immunological perspective. The... 相似文献
998.
999.
Mehdi Mahmoudiniya Shahram Kheirandish Mohsen Asadiasadabad 《Transactions of the Indian Institute of Metals》2017,70(5):1251-1259
In the present study the effect of room temperature rolling on microstructure and mechanical properties of a new Cr–Mn austenitic stainless steel (containing 12 %Cr, 23 %Mn and 0.13 %C) and AISI 316 steel was investigated. The specimens of these steels were cold rolled at various thickness reductions of 0, 12, 25, 37 and 50 %. Microstructural investigations were carried out using optical microscopy, magnetic field test and X-ray diffraction technique. Hardness and tensile test methods were also done to evaluate the mechanical properties. Results showed that some of austenite phase transformed to martensite during cold rolling in the 316 steel, while there was no strain induced transformation in the Cr–Mn steel. It was also found that the newly developed steel had higher strength and higher specific strength than those of the 316 steel, while its ductility was the same as that of the 316. 相似文献
1000.
Fatemeh Sadat HOSEINIAN Aliakbar ABDOLLAHZADE Saeed Soltani MOHAMADI Mohsen HASHEMZADEH 《中国有色金属学会会刊》2017,27(3):686-693
The artificial neural network (ANN) and hybrid of artificial neural network and genetic algorithm (GANN) were applied to predict the optimized conditions of column leaching of copper oxide ore with relations of input and output data. The leaching experiments were performed in three columns with the heights of 2, 4 and 6 m and in particle size of <25.4 and <50.8 mm. The effects of different operating parameters such as column height, particle size, acid flow rate and leaching time were studied to optimize the conditions to achieve the maximum recovery of copper using column leaching in pilot scale. It was found that the recovery increased with increasing the acid flow rate and leaching time and decreasing particle size and column height. The efficiency of GANN and ANN algorithms was compared with each other. The results showed that GANN is more efficient than ANN in predicting copper recovery. The proposed model can be used to predict the Cu recovery with a reasonable error. 相似文献