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91.
The potential of industrial porous concrete for using as a template for the synthesis of porous carbon materials has been investigated. Carbon replicas of porous concrete have been prepared by carbonization of sucrose. The pores of the resulting carbon materials range from the macropore to the micropore region, pointing to a hierarchy. 相似文献
92.
In recent years the beveloid gear, also known as conical involute gear, is shifting more and more into the spotlight. The beveloid gear has been an important part of marine transmissions for years and is nowadays used to transmit the torque of the output shaft of the gearbox onto the front axle in a four wheel drive vehicle. The small need of design space and the reduced amount of design parts necessary in comparison to conventional transfer gearboxes, distinguish the beveloid gear. The conjugate flank of beveloid gears promises the best operational behavior. However because of its geometry the conjugate flank cannot be manufactured with standard manufacturing processes. Standard modification such as crowning offer a possibility to enhance the operational behavior of involute beveloid gears but cannot reach the whole potential given by conjugated beveloid gears. Therefore, the objective of the following report is to investigate the potential of free flank modifications of beveloid gears regarding the operational behavior. After a brief overview on existing geometry optimization methods for beveloid gears, the method for free flank modifications by means of a weighted objective function is defined and applied to an example gear. The results of the investigation show that free flank modifications offer a high level of improvement of the operational behavior. The comparison with a non-modified gear, a gear with standard modifications and a gear with free flank modifications for three different load steps proves that free flank modifications offer a higher durability and lower noise excitation. 相似文献
93.
Co-doping effects of (Al,Ti, Mg) on the microstructure and electrical behavior of ZnO-based ceramics
Qianying Sun Guorong Li Tian Tian Jiangtao Zeng Kunyu Zhao Liaoying Zheng Maud Barré Jens Dittmer Francois Gouttenoire Anthony Rousseau Abdel Hadi Kassiba 《Journal of the American Ceramic Society》2020,103(5):3194-3204
Co-doped ZnO-based ceramics using Al, Ti, and Mg ions in different ratios were synthesized with the objective to investigate the doping effects on the crystalline features, microstructure and the electrical behavior. For Al and Ti doping, a coexistence of crystalline phases was shown with a major wurtzite ZnO structure and secondary spinel phases (ZnAl2O4, Zn2TiO4, or ZnaTibAlcOd), while Mg doping did not alter significantly the structural features of the wurtzite ZnO phase. The electrical behavior induced by Al, Ti, and Mg co-doping in different ratios was investigated using Raman, electron paramagnetic resonance (EPR) and 27Al and 67Zn solid-state nuclear magnetic resonance (NMR). Al doping induces a high electrical conductivity compared to other doping elements. In particular, shallow donors from Zni-AlZn defect structures are inferred from the characteristic NMR signal at about 185 ppm; that is, quite far from the usual oxygen coordinated Al. The Knight shift effect emanating from a highly conducting Al-doped ZnO ceramics was considered as the origin of this observation. Oppositely, as Ti doping leads to the formation of secondary spinel phases, EPR analysis shows a high concentration of Ti3+ ions which limit the electrical conductivity. The correlation between the structural features at the local order, the involved defects and the electrical behavior as function of the doping process are discussed. 相似文献
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Norgauer Philipp Grunewald Laura Priester Lena Heilemann Jens Hein Michael Stahl Karsten 《Forschung im Ingenieurwesen》2020,84(2):141-150
Forschung im Ingenieurwesen - Schneckengetriebe finden sich in verschiedenen Anwendungen als Stell- und Leistungsgetriebe. Aufgrund der Realisierbarkeit einer hohen Übersetzung bei kleinem... 相似文献
99.
Profile accuracy, no burning and residual compressive stresses at the tooth root fillet are required for the durability of highly stressed gears. This paper reveals the challenges for continuous generating grinding with corundum and CBN. For this purpose, material removal simulations and experimental investigations were carried out to gain knowledge of the tool–workpiece contact conditions. The potential of CBN tools was analysed due to the fact that the mechanical loads at the grinding worm tip result in high profile wear of the corundum tools. In this context, especially the interrelationship between the dressing strategy and the workpiece quality was investigated in detail. 相似文献
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