共查询到20条相似文献,搜索用时 218 毫秒
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《中国有色金属学报》2015,(6)
采用凝胶注模成型技术制备ZnO陶瓷坯体,并在较低温度下常压烧结后获得相对密度达98.6%、晶粒尺寸为1.35μm的陶瓷靶材,研究工艺参数对ZnO陶瓷靶材的相对密度、晶粒生长和电阻率的影响。结果表明:ZnO陶瓷靶材的相对密度随烧结温度升高而增大,在1050℃时达到最大值。适当增大升温速率或延长保温时间都有利于提高其相对密度。晶粒尺寸随升温速率的升高而减小,随保温时间的延长而增大。提高烧结温度和增加保温时间都可降低ZnO陶瓷靶材的电阻率。ZnO陶瓷靶材经1400℃烧结3 h后,获得的电阻率最小(为1.75×10-2?·cm)。 相似文献
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采用电火花电解(EDM/ECM)复合加工方法进行割缝加工时,加工效率和割缝宽度作为评价复合加工割缝的两个重要指标,但在实际加工过程中往往难以同时达到要求。使用自行研制的水包油工作液,利用单因素法探究电火花电解复合加工时工艺参数(电流、脉冲宽度、脉冲间隙、电极盘转速)对复合加工效果的影响规律,并通过正交实验分析不同工艺参数对电火花电解复合加工的影响程度,确定最佳工艺参数组合。最终通过正交试验,综合考虑加工效率及缝宽这两个评价指标选择缝宽最优1 (A_1B_1C_3D_1),即确定工艺参数组合电流40 A,脉冲间隙10μs,电极盘转速400 r/min,脉冲宽度44μs为水包油工作液复合加工的最优参数。 相似文献
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通过对TiN/Si3N4复相陶瓷电火花线切割加工电参数的优化试验,找出影响加工效率的主要因素和较优的参数组合,为进一步开发TiN/Si3N4复相陶瓷材料的加工及应用提供依据. 相似文献
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Hyun-Seok TAK Chang-Seung HA Ho-Jun LEE Hyung-Woo LEE Young-Keun JEONG Myung-Chang KANG 《中国有色金属学会会刊》2011,(Z1)
The characteristic evaluation of aluminum oxide (Al2O3)/carbon nanotubes (CNTs) hybrid composites for micro-electrical discharge machining (EDM) was described. Alumina matrix composites reinforced with CNTs were fabricated by a catalytic chemical vapor deposition method. Al2O3 composites with different CNT concentrations were synthesized. The electrical characteristic of Al2O3/CNTs composites was examined. These composites were machined by the EDM process according to the various EDM parameters, and the cha... 相似文献
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A. Muttamara Y. Fukuzawa N. Mohri T. Tani 《Journal of Materials Processing Technology》2009,209(5):2545-2552
Technologies for machining advanced insulating ceramics are demanded in many industrial fields. Recently, several insulating ceramics, such as Si3N4, SiC and ZrO2, have been successfully machined by electrical discharge machining (EDM). As unstable discharges occur during the machining of Al2O3 ceramics, inferior machining properties have been obtained. The formation mechanism of the electrical conductive layer on the EDMed surface is much different as compared to other ceramics. In addition to this, the electrically conductive layers are not formed sufficiently to adhere to the EDMed workpiece surface and keep a stable and continuous discharge generation on the ceramics. Graphite is widely used as electrode material in EDM. It is expected that carbon from graphite electrode implant and generate a conductive layer. Copper, graphite (Poco EDM-3) and copper-infiltrated-graphite (Poco EDM-C3) electrodes were used to compare the effects of generation of a conductive layer on alumina corresponding to EDM properties. The electrical discharge machining of 95% pure alumina shows that the EDM-C3 performs very well, giving significantly higher material removal rate (MRR) and lower electrode wear ratio than the EDM-3 and copper electrodes. The value of MRR was found to increase by 60% for EDM-3 with positive electrode polarity. As for EDM-C3, MRR was increased by 80% under the same condition. When the results were investigated with energy dispersive spectroscopy (EDS), no element of copper was observed on the conductive layer with both EDM-3 and EDM-C3. However, surface resistivity of a conductive layer created with EDM-C3 is less than with EDM-3. Surface roughness was improved to 25 μm with positive polarity of EDM-C3. 相似文献
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Lin Gu Lei LiWansheng Zhao K.P. Rajurkar 《International Journal of Machine Tools and Manufacture》2012,53(1):100-106
The aim of this study is to investigate an efficient Ti6Al4V electrical discharge machining (EDM) process with a bundled die-sinking electrode. The feasibility of machining Ti6Al4V with a bundled electrode was studied and its effect on EDM performance was compared experimentally using a solid die-sinking electrode. The simulation results explain the high performance of the EDM process with a bundled electrode by through the use of multi-hole inner flushing to efficiently remove molten material from the inter-electrode gap and through the improved ability to apply a higher peak current. A 3-factor, 3-level experimental design was used to study the relationships between 2 machining performance parameters (material removal rate: MRR, tool wear ratio: TWR) and 3 machining parameters (fluid flow rate, peak current and pulse duration). The main effects and influences of the 2-factor interactions of these parameters on the performances of the EDM process with the bundled electrode are discussed. 相似文献
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SeongMin Son HanSeok Lim A.S. Kumar M. Rahman 《Journal of Materials Processing Technology》2007,190(1-3):73-76
Micro EDM is one of the most powerful technologies which are capable of fabricating micro-structure. However, there are many operating parameters that affect the micro EDM process. Since the EDM is basically a thermal process, the supplying electrical condition can be an important factor. The conditions generally consist of several parameters such as electrical current, voltage, pulse duration, spark gap, and others. Those are decisive in removal rate, wear rate, and machining accuracy, which are characteristics of EDM. In this study, the influences of EDM pulse condition on the micro EDM properties were investigated. Voltage, current, and on/off time of the pulse were selected as experimental parameters based on a simple equation for the material removal rate. The pulse condition is particularly focused on the pulse duration and the ratio of off-time to on-time, and the machining properties are reported on tool wear, material removal rate, and machining accuracy. The experimental results show that the voltage and current of the pulse exert strongly to the machining properties and the shorter EDM pulse is more efficient to make a precision part with a higher material removal rate. 相似文献
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针对SiCp/Al的加工,提出一种超声振动磨削放电复合加工的方法.从加工效率、加工稳定性及表面质量等方面与电火花加工进行了对比试验研究。分析了两种加工方法的脉冲宽度和峰值电流对加工速度和表面粗糙度的影响,结果表明:电火花加工的表面粗糙度平均值为尺04.5μm,超声振动磨削放电复合加工的表面粗糙度平均值为Ra2μm:超声振动磨削放电复合加工的稳定性比电火花加工好,但加工速度较低。通过扫描电镜对两种加工方法下零件表面形貌和重熔层进行了观测,对试件表面进行了X射线衍射分析,表明采用超声振动磨削放电复合加工SiCp/Al复合材料可获得较好的表面质量。 相似文献
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Apiwat Muttamara Yasushi Fukuzawa Naotake Mohri Takayuki Tani 《Journal of Materials Processing Technology》2003,140(1-3):243-247
Electrical discharge machining (EDM) is used as a precision machining method for the electrically conductive hard materials with a soft electrode material. But recently we succeeded to machine on insulating material by EDM. The technology is named as an assisting electrode method. The EDMed surface is covered with the electrical conductive layer during discharge. The layer holds the electrical conductivity during discharge. For micro-EDM, the wear of tool electrode becomes lager ratio than the normal machining. So the micro-machining is extremely difficult to get the precision sample.
In this paper to obtain a fine and precise ceramics sample, some trials were carried out considering the EDM conditions, tool electrodes material and assisting electrode materials. Insulating Si3N4 ceramics were used for workpiece. The machining properties were estimated by the removal rate and tool wear ratio. To confirm the change of micro-machining process, the discharge waveforms were observed. The micro-machining of the Ø0.05 mm hole could be machined with the commercial sinking electrical discharge machine. 相似文献
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Biing Hwa Yan Che Chung Wang Han Ming Chow Yan Cherng Lin 《International Journal of Machine Tools and Manufacture》2000,40(10):1403
This study investigates the feasibility and optimization of a rotary EDM with ball burnishing for inspecting the machinability of Al2O3/6061Al composite using the Taguchi method. Three ZrO2 balls attached as additional components behind the electrode tool offer immediate burnishing following EDM. Three observed values (machining rate, surface roughness and improvement of surface roughness) are adopted to verify the optimization of the machining technique. In addition, six independent parameters are chosen as variables for evaluating the Taguchi method; these variables are categorized into two groups: (1) electrical parameters, i.e. peak current, pulse duration and non-load voltage; and (2) non-electrical parameters, i.e. flushing pressure of dielectric, rotational speed of electrode and residual height of hump. Experimental results indicated a feasible technique for applying rotary EDM with ball burnishing in machining the Al2O3/6061 composite. Optimization of this technique is also discussed. 相似文献
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《CIRP Annals》1988,37(2):623-631
As a thermal machining process, Electro-Discharge Machining (EDM) provides a means of machining ceramic materials, irrespective of their hardness and strength, provided that their electrical conductivity values are of the order of 0.01 S/cm (100 Ω*cm), as is sometimes the case with engineering ceramics.EDM achieves high removal rates as compared with traditional techniques for the machining of these materials. The lack of correlation between the cutting rate, the surface roughness and the physical material parameters confirms that the removal mechanisms for machining conductive ceramics differ from those involved in metal machining. In order to ensure process stability, the grain structure evinced by the ceramic must be as fine and homogeneous as possible. The complex workpiece geometries and high accuracy to shape and size attainable with electro-discharge machining particularly favour its use in toolmaking. 相似文献
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工程陶瓷材料硬脆、导电率低,难以获得高效精密的电加工效果.本文针对工程陶瓷电火花加工特点,在分析国内外工程陶瓷电火花加工技术的基础上,提出了基于遗传算法的工程陶瓷电火花加工方法.该方法结合遗传算法、神经网络及模糊控制理论构造了多环式自适应控制系统,在线对加工过程进行断丝预防、加工工艺自适应和加工参数自适应监测与控制,从而为难加工材料实现高效精密的电火花加工提供理论与技术指导. 相似文献