Spark erosion

Eor drilling, the discharge action occurs at the leading edge of the tool, whereas ECM takes place on the side walls between the tool and the workpiece. The combined spark erosion and ECM action yields fast rates of metal removal. Because ECM is stiU possible, any metallurgical damage to the components caused by the sparking action can be removed by a short period (eg, 15 s) of ECM after the main ECAM action. Currents of 250 A at 30 V are typically used in the process. 

Tips of platinum, platinum—nickel alloy, or iridium can be resistance-welded to spark-plug electrodes for improved reHabiHty and increased lifetime. These electrodes are exposed to extremely hostile environments involving spark erosion, high temperature corrosion, thermal shock, and thermal fatigue. 

Electro discharge (spark erosion) techniques rely heavily on the ability of EDM oil to act as an electrical insu-lant, to dissipate heat from the electrode, and to flush away erosion debris from the workpiece. EDM oils also are suitable for all die-sinking spark erosion operations. They should have low aromatic levels, good filterability, low fuming, high dielectric strength, excellent oxidation resistance and low color level. 

The cellular reaction product consisted of alternating plates of C03W lamellae in a solute-depleted Co matrix (eCo). Ffomogenized ingots were cut into slices 1 mm thick and then heat-treated. Spark erosion was used to trepan 3 mm diameter discs which were then jet electropolished to form thin foils for TEM examination in a Philips EM 430 STEM instrument operating at 300 kV in the nanoprobe mode with a probe size of 5 to 10 nm. 

Mo bicrystal slices of 1 mm thickness were cut by spark erosion, then mechanically thinned to a thickness of 0.1mm. Discs of 3 mm diameter were then prepared and placed in the experimental assembly illustrated in Figure 5.44. 

The nickel-chrome alloy is available from the Dunlop Aviation Group and has the trade name of Retimet . Retimet is suitable, although its affinity for the organic phase is greater than for the aqueous phase. In order to produce approximately equal affinity for each phase the discs were gold plated for 10 min using a current of 300 mA. It is preferable that the alloy is shaped so that the pore structure is maintained on the surface after machining. Spark erosion is used to shape the material. 

Fig. 8. Spark erosion technique and drag reduction equipment.

At this point we want to thank Dr. Drews from the PTB, Braunschweig for his generous support in applying the spark erosion technique. 

The procedures for sample preparation, mounting and cleaning have been described previously (26). Briefly, the rhodium single crystal rod was oriented to 1/2° using X-ray back reflection and a 1 mm. thick disc was cut by spark erosion. After mechanical... 

Fig. 8. Integrated microreaction system containing mixing units and heat exchangers a Integrated system in photoetchable glass made by photolithography and wet etching, b Detail of an integrated system in a special alloy made by micro spark erosion (EDM-grinding)...

In addition, standard methods of precision mechanical engineering like micromilling [61] and micro spark erosion [62] can be applied for fabricating components of microreactors. In order to achieve low-cost mass fabrication... 

The range of surface quality reached with the different techniques is widespread depending on the material as well as on the machining parameters. Spark erosion techniques lead to a considerably rough surface. The surface quality obtained with laser ablation heavily depends on the material to be structured and on the correct parameter settings. Values between some 10 pm and about 1 pm are common. In... 

Keywords carbon nanomaterials, exploding wires, spark erosion, fullerene-like clusters, ferromagnetic nanomaterials... 

There were developed two new technologies for manufacturing of novel carbon nanomaterials (fullerenes, nanotubes, carbonic nanoclusters) based on the idea of high-energy plasmochemistry synthesis with the use of the methods of electrical wire explosion and spark erosion of graphite and metallic materials (nickel, iron, copper) in organic medium. 

An important role of the catalysts (Ni, Cu, Fe) for the spectral composition, structural state and physical properties of the carbon nanomaterials produced with the electrical wire explosion and spark erosion methods was established. 

Berkowitz A.E., Hansen M.F., Parker F.T. et al. (2003) Amorphous soft magnetic particles produced by spark erosion, J. Magn. Mater. 254-255, 1-6. 

Chuistov K.V., Perekos A.E., Zalutskiy V.P., Efimova T.V., Glavatskaya N.I. The effect of production conditions on the structural state, phase composition and fineness of iron and iron-based powders made by electric-spark erosion. Metal Physics and Advanced Technologies 1997 16(8) 865-75. 

Table 3. Parameters of aluminium hydroxide received by electric spark erosion.

A. A. Shcherba, A. D. Podoltsev, and I. N. Kucherjavaya, Spark erosion of conducting granules in a liquid analysis of electromagnetic, thermal and hydrodynamic processes, Technical Electrodynamics, No. 6, 4-17 (2004). 

Although most work related to pore formation in silicon has involved electrochemical etching of silicon in HF solutions, porous silicon layers have also been formed by chemical etching and by spark erosion in vacuum. 

Hummel and Chang have shown that porous films can also been formed by a spark erosion technique [110]. The morphologies of these porous films exhibit less anisotropy than electrochemically formed porous structures although the pores propagate perpendicular to the surface. The growth rates of about 0.3 nm s are much slower than those of electrochemically formed porous layers. Porous layers formed in air and under nitrogen exhibited visible photoluminescence similar to the emission spectra obtained from electrochemically grown porous layers. 

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