管电极电解加工工艺过程稳定性研究

为提高管电极电解加工的稳定性,对管电极电解加工的极间流场进行建模仿真,分析底面流场分布与加工稳定性的关系。仿真所得到的底面压强分布变化规律表明,侧面间隙、底面间隙以及电解液流速均对底面流场分布有重大影响,从而影响管电极电解加工的过程稳定性。结合仿真分析,通过对影响加工稳定性的主要工艺参数,如绝缘层的涂覆厚度、工具进给速度、电解液供液压力进行优化,减少深小孔加工中火花、短路等现象的发生。采用优化的参数,利用群电极成功加工出深宽比为2的7×7小孔阵列,加工过程稳定,孔径均匀。     

线电极微幅振动电解线切割研究

通过线电极叠加轴向微振动促进加工间隙中的电解产物排除,改善线电极电解线切割的稳定性,提高加工效率。自行研制线电极微幅振动电解加工系统,阐述线电极微幅振动电解加工原理,建立加工间隙产物排除的数学模型,揭示线电极叠加轴向微幅振动是排除电解产物、更新电解液的有效途径之一,分析线电极叠加轴向微幅振动对加工稳定性、加工效率和加工精度的影响。针对线电极叠加轴向微幅振动和不叠加振动两种情况进行了对比试验,试验结果表明,振幅8μm、频率10Hz的振动参数有利于改善线电极电解线切割稳定性,提高加工效率。与不叠加振动相比,线电极叠加轴向微幅振动情况下,线电极电解线切割可以在较小的电压、脉冲宽度和较大的脉冲周期下稳定进行,有效地缩小切缝宽度,提高了加工精度。采用优化后的振动参数和加工参数,在不锈钢工件(0Cr18Ni9)上加工出12μm的微缝以及形状复杂的微渐开线齿轮和微螺旋结构。     

表面修饰CuS纳米颗粒的合成及其摩擦学性能研究

在无水乙醇与蒸馏水混合溶剂中合成了油酸修饰的CuS纳米颗粒,根据表面修饰剂与产物CuS的摩尔比不同,分别制备出了油酸与CuS纳米颗粒的摩尔比为0.5∶1,1∶1,2∶1,3∶1的产物。在FALEX-6型四球试验机上考察了其作为润滑油添加剂在液体石蜡中的摩擦学性能,并用透射电子显微镜(TEM)对磨斑表面形貌进行分析。结果表明:在添加剂质量分数都为0.5%时,当油酸与CuS纳米颗粒的摩尔比为2∶1时,磨斑直径下降最大,抗磨效果达到最好;当油酸与CuS的摩尔比为1∶1,摩擦因数为最小值,减摩效果达到最好。     

聚电解质原位生长CuS纳米粒子分子沉积膜的制备及表征

采用分子沉积技术制备了基础聚二烯丙基二甲基氯化铵/聚丙烯酸分子沉积(MD)膜,然后在基础MD膜中原位反应生长了CuS粒子;利用紫外一可见分光光度计、X射线光电子能谱仪及原子力显微镜对此膜进行了表征.结果表明:在膜中原位生长的CuS颗粒为纳米粒子,且纳米粒子在膜中分布均匀,无明显团聚现象;随着反应时间的增加,纳米粒子的粒径明显增大;随着循环反应次数的增加,除纳米粒子的粒径略有增大外,纳米粒子的数量也明显增多.     

螺旋电极电解扩孔工艺研究

介绍了螺旋电极电解扩孔，该方法兼有小间隙电解加工和脉冲电流电解加工的优点，用于硬质金属材料导孔的加工是一种行之有效的新的工艺方法，文对其中原理。加工实验研究和基本工艺规律作了综述。     

带双极电极的电解加工

如何降低加工间隙中气体密集度的问题,目前已引起电解加工行业的极大关注。这是因为加工过程中析出的气体,对于加工精度、生产率、耗电量以及表面质量等电解加工工艺特性,都将产生不良的影响。而加工间隙中气体浓度不均匀以及阴极附近的超高浓度乃是导致这种不良影响的主要原因。这样将使电解液的导电率降低和电流密度沿加工间隙通道长度的相应分配。当加工长尺寸     

盘研究电极接实地的双恒电位仪

研制了一种盘研究电极接实地的双研究电极恒电位仪。采用集成电位跟随器作盘电极电流测试.这种双恒克服了零阻电流计的固有缺点,具有控制精确、线路简单、稳定性好、使用方便等优点.     

新型碳纤维海洋电场电极的制备及性能研究

针对传统碳纤维电极易受电容容抗效应影响而无法响应低频信号的问题,采用浓硝酸氧化+硅溶胶涂覆的改性方法,制备了一种新型的碳纤维海洋电场电极。实验结果证明,改性后碳纤维表面引入了大量氮氧官能团,使得电极比表面积和亲水性得到大大提高,同时电极受容抗效应的影响减小。在电场响应性能方面,改性后电极能够正确响应低至1 m Hz的低频信号,相较于改性前,响应的准确性和灵敏度也得到大大提高,改性后电极对10和1 m Hz信号响应的线性度分别为3. 3%、2. 1%,灵敏度分别为0. 048 2,0. 050 3。     

二氧化钌薄膜电极的制备及其性能研究

用热分解Ru(OC2H5)3的方法,在金属钽板上制备二氧化钌薄膜,作为超级电容器的电极.通过循环伏安、交流阻抗和恒流充放电等测试方法,得出二氧化钌薄膜电极的比电容为362F/g,内电阻为1.08Ω,且若干次循环充放电后,内电阻和电容量保持不变,具有良好的电化学稳定性、长寿命和快速充放电的能力,是一种理想的超级电容器电极.     

超细活性炭与电极的制备和性能

用自制振动磨对商业用活性炭进行研磨，分析了活性炭的结构（比表面积、孔径分布）和制成电极后的电化学及充放电性能。结果表明：经过研磨后的活性炭，比表面积从原1739．8m^2／g增加到2215m^2／g，增幅为27%；微孔容积增加25％，中孔容积增加30％，研磨后活性炭电极的比容量达到213．4F／g。     

电火花加工多材质电极制备方法及试验研究

随着电火花加工技术的不断发展,利用多材质电极来实现微小复杂曲面的电火花成形加工,具有加工速度快、一次成形等特点而被广泛应用.针对多材质电极的制备,以黄铜、紫铜、铁、钼及铜钨合金等材质电极在模具钢上进行了加工试验,以研究的电极损耗及形状变化规律为基础,根据复杂曲面加工需求设计多材质电极,运用热镀法制备多材质电极,通过扫描...     

电火花加工中电极材料对加工性能影响的试验研究

以电火花多电极加工3Cr13模具型腔为研究对象,以提高材料去除率和降低电极损耗为目标,对负极性标准切入加工时不同电极材料的电火花加工性能(加工效率、电极损耗)进行研究,设计并进行了不同工艺参数下紫铜电极和Cu50W铜钨合金电极加工试验,获得了不同条件下的材料去除率和电极相对损耗参数,并对多电极电火花加工工艺及经济性进行了分析,结果表明:相同工艺参数下,加工性能因电极材料热学性能不同而不同,Cu50W铜钨合金的材料去除率约为紫铜的85.7％,而电极相对损耗约为紫铜的42.9％,从而为电火花加工不锈钢模具材料的电极选择提供了理论依据.     

Workpiece and electrode influence on micro-EDM drilling performance

In recent years, the need for products containing micro-features has shown a pronounced and steady growth in several fields of application. For the development of micro-holed devices, one of the most important technologies is micro-EDM (Electro Discharge Machining). Micro-EDM can be considered as an ideal process to obtain burr-free micron-size features with high aspect ratios. In particular, micro-EDM is a non-contact material removal process in which rapid electric spark discharges remove the material composing the workpiece by means of melting and vaporizing phenomena. The present work deals with the fabrication of micro holes using micro-EDM technology. The investigation focuses on the influence of different electrodes and workpiece materials on the process performance, expressed in terms of tool wear ratio. In particular, the influence of four different workpiece materials (stainless steel, titanium, magnesium and brass), three electrode materials (copper, brass and tungsten carbide) and two different electrode shapes (cylindrical and tubular) was investigated. Moreover, an analysis of the geometrical characteristics of the micro holes in terms of conicity and diametrical overcut was carried out. An influence of electrode geometries, electrode material and workpiece material on the final output was found.     

球形镍金基体真空镀汞膜电极的研制及性能测试

研制了一种球形镍金基体真空镀汞膜电极。采用2．5次微分极语法对电极性能进行了考查,在0.1MKCl中,镉的线性范围为4×10~(－8)－6×10~(－11)M,证明该电极性能稳定,灵敏度高,重视性好。     

Influence of flushing on performance of EDM with bunched electrode

The existing applications of electrical discharge machining (EDM) for bulk material removal are restricted by their comparatively low material removal rates. The bunched-electrode EDM proposed in this study, using the powerful multi-hole inner flushing, is an effective way of being released from this restriction. This paper investigates the mechanism by which flushing (flushing modes and flushing parameters) influences machining performance indices, i.e., material removal rate and tool wear rate, using experiments and simulations. Based on an investigation conducted, compared with traditional solid electrode with mono-hole inner flushing, a bunched electrode with multi-hole inner flushing endures higher peak current and results in larger material removal rate and higher relative tool wear ratio because of a more effective flushing process. By properly choosing inlet velocity and electrode effective-area ratio, a higher material removal rate is achieved and relative tool wear ratio is kept at a lower level.     

水溶性富勒烯C60的制备及其血液相容性研究

目的 ：制备γ环糊精-C60超分子化合物,改善C60的水溶性和血液相容性。方法：采用研磨法制备γ环糊精-C60超分子化合物,利用红外光谱对其结构进行表征,通过溶血实验及血浆复钙实验对C60、γ环糊精-C60的血液相容性进行评价。结果：红外光谱结果表明γ环糊精与C60发生包埋,γ环糊精-C60在双蒸水中放置24h无聚沉,样品浓度为512μg/mL、102.4μg/mL、25.6μg/mL时,C60的溶血率分别为13.75%±0.26%、6.02±0.12%、3.21±0.19%,γ环糊精-C60的溶血率分别为3.74%±0.39%、1.13%±0.12%、0.55%±0.19%;阳性对照、C60、γ环糊精-C60的复钙时间分别为10min、15min、20min,对应吸光度值分别为1.09、0.68、0.51。结论：经γ环糊精修饰后C60的水溶性和血液相容性得到改善。     

A study of electrochemical deburring using a moving electrode

The electrochemical deburring process with graphite balls was investigated using turned aluminium specimens. Three different types of electrolyte were compared for quality of deburring and metal dissolution rate. Micrographs of deburred samples were analysed to evaluate deburring quality.     

An experimental study on the performance and emission characteristics of a CI engine fuelled with Jatropha biodiesel and its blends with diesel

The performance and emission characteristics of a compression ignition engine using mixture of jatropha biodiesel and mineral diesel have been experimentally investigated. It is observed that brake specific fuel consumption increases with higher percentage of biodiesel in the blends. Brake thermal efficiency decreases with the increased percentage of biodiesel in the blends. The maximum efficiency is found to be 29.6% with pure diesel and 21.2% with pure biodiesel. Carbon mono-oxide and hydrocarbon emissions are improved with the addition of biodiesel to diesel. NO_x emission is found to be increased with pure biodiesel by 24% compared to mineral diesel.     

A free-jet experimental study on the performance of a cavity-type ramjet

Free jet experiments have been conducted to evaluate the performance of a cavity-type ramjet. To prevent uncertainty of combustion parameters, a method to calculate internal thrust from cold flow parameters is brought forward. According to this analysis method, the internal thrust of the cavity-type ramjet increases linearly with the stoichiometric ratio while the specific impulse decreases squarely. The aero-propulsive balance of a conceptive missile is also examined, focusing on the effect of attack angle. Considering both efficiency and performance, an attack angle of 3∼6 degrees is recommended. And the free-jet experimental results show that the cavity-type ramjet can supply sufficient thrust for the missile under cruise conditions.