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41.
《Ceramics International》2015,41(7):8742-8747
The polyaluminium chloride (PACl) precursor was used for a simple and scaled-up mechanochemical-molten salt synthesis of α-Al2O3 platelets. PACl, as a low temperature α-Al2O3 precursor, was firstly mechanically activated by high-energy ball milling for 5 min, followed by a next 5 min ball milling in the presence of a NaCl–KCl salt mixture. The starting formation temperature of the α-Al2O3 phase was 600 °C. In the subsequent annealing in the temperature range of 660–1000 °C, the α-Al2O3 phase with a well developed plate-like morphology was obtained. The products were characterized by X-ray powder diffractometry, scanning electron microscopy (SEM), and thermal analysis (DTA, TG) and solution 27Al NMR spectroscopy. 相似文献
42.
基于工程粗糙表面的微观形貌具有统计自相似分形特征,将分形几何学运用于金属材料表面形貌研究。粗糙表面的分形参数与加工条件密切相关。铣削加工过程中,切削参数会影响表面分形维数和表面粗糙度,考察了分形维数和传统表面粗糙度参数之间的关系,分别建立铣削参数与表面分形维数和表面粗糙度之间关系模型,并采用实验进行验证。实验结果表明,铣削加工表面具有分形特征;铣削表面分形维数D基本不随切削速度增加而变化,但表面粗糙度Ra会随切削速度的增加而减小;表面粗糙度与加工进给量成正相关,分形维数先增大后减小,并存在临界点;分形维数D与表面粗糙度Ra呈幂指数关系;所建立模型合理。相关研究结果可以为提高工程表面的使用性能及降低成本提供参考。 相似文献
43.
《应用陶瓷进展》2013,112(2):117-122
AbstractThis paper presents a dry mechanochemical process to produce hydroxyapatite (HAp) nanoparticles. Two distinct chemical reactions are introduced to prepare HAp powders using milling process. Structural and morphological properties of the obtained materials are studied by X-ray diffraction and transmission electron microscopy. The results reveal that the single crystal HAp nanoparticles have been successfully produced in metallic and polymeric vials through two different experimental procedures. Tempered chrome steel and polyamide-6 materials are adopted as the metallic and polymeric vials respectively. Nanoellipse, nanorod and nanosphere powders are obtained in these experimental procedures. Moreover, the obtained HAp powders through two distinct reactions exhibit average sizes about 12 and 15?nm using the tempered chrome steel vials, and about 16 and 17?nm using the polyamide-6 vials. The results indicate that single crystal HAp nanoparticles produced in polyamide-6 vials have suitable morphology and high production efficiency without any chemically stable contaminations. 相似文献
44.
45.
《Machining Science and Technology》2013,17(3):377-397
Abstract This article describes the development of three-dimensional stability surfaces, or maps, that combine the traditional dependence of allowable (chatter-free) chip width on spindle speed with the inherent dependence on tool overhang length, due to the corresponding changes in the system dynamics with overhang. The tool point frequency response, which is required as input to existing stability lobe calculations, is determined analytically using Receptance Coupling Substructure Analysis (RCSA). In this method, a model of the tool, which includes overhang length as a variable, is coupled to an experimental measurement of the holder/spindle substructure through empirical connection parameters. The assembly frequency response at the tool point can then be predicted for variations in tool overhang length. Using the graphs developed in this study, the technique of tool tuning, described previously in the literature, can then be carried out to select a tool overhang length for maximized material removal rate. Experimental results for both frequency response predictions and milling stability are presented. 相似文献
46.
Chidambaram Narayanan Reto BalzDaniel A. Weiss Kurt C. Heiniger 《Journal of Materials Processing Technology》2013,213(12):2201-2210
A phenomenological model of the three-phase flow inside an abrasive water jet machining cutting head has been developed. Several improvements over previously presented models such as taking into account the abrasive particle size distribution, and the effect of breakage of particles on the energy flux have been made. The model has been validated using an extensive set of experimental data with wide variations in cutting-head geometry, operating pressure, and abrasive mass flow rates. The cross-sectional averaged abrasive particle velocity at the exit of the focussing tube has been predicted with good accuracy over the whole range of experiments. In particular, the Pearson correlation between the model and the experimental results is found to be more than 95%, implying the utility of this model in design. 相似文献
47.
Design,refinement, implementation and prototype testing of a reconfigurable lathe-mill 总被引:1,自引:0,他引:1
This article documents the design, refinement, and implementation of a reconfigurable machine tool that provides a flexible platform for turning and milling. Advances in the design and capabilities of machine tools drive modern industry. In fact, the expanding capabilities of the machines permit novel and economic changes in the manufacturing and design of products. After the flexible manufacturing (FMS) boom, a more recent, but no less significant, area of machine development involves the reconfiguration of milling machines. This reconfigurability can also be applied to lathe-mills. The present work demonstrates satisfactorily the reconfiguration characteristics of modularity, integrability, and convertibility. We prototype and test a completely functional bench top reconfigurable lathe mill machine implemented using a $10,000 USD budget and developed following a synthesized machine tool product development methodology that begins with concept design and cutting forces to end in prototyping. In addition to reasonable results in runout, positioning, and surface roughness, the machine demonstrates the capability to produce parts with a Cpk of 1.009, thereby demonstrating the ability to fabricate this type of machine in Mexico for the local jewelry industry. 相似文献
48.
汪洋 《机电产品开发与创新》2011,24(4):177-178
通过研究风电增速箱齿圈的几个工艺难点,分析工艺方法,通过几年的实践,解决了齿圈难以上批量的工艺瓶颈问题. 相似文献
49.
P.J. Wilson S. BlackburnR.W. Greenwood B. PrajaptiK. Smalley 《Journal of the European Ceramic Society》2011,31(6):977-981
The amount of alumina contamination present in ball-milled silica powders has been shown to increase with increased mill time for materials manufactured during the same time period. This alumina contamination level has also been observed to vary depending on the date, and possibly the state of repair, of the ball mill itself. The associated alumina level has been shown to significantly influence the high temperature properties (at 1475 °C) of the materials, with high contamination levels not only resulting in increased flexural strength and creep resistance, but also increasing the thermal contraction of the materials when dilatometer measurements were performed to 1600 °C. 相似文献
50.