Fabrication of tungsten micro-rods using electrolyte jet turning method

摘要

The electrolyte jet turning (EJT) method was used to fabricate tungsten micro-rods with the neutral sodium nitrate (NaNO_3) aqueous solution as electrolyte. Since the non-conductive oxide film generated on the surface of tungsten interrupts the electrochemical dissolution process, a bipolar current was needed to remove the oxide film during machining. With the bipolar current, sodium hydroxide (NaOH) is generated, when the polarity of the tungsten electrode is negative, enabling the removal of oxide film. A cylindrical nozzle was used for the EJT to jet electrolyte to the surface of workpiece which was rotated with a rotation speed of 3000 rpm. The inner diameter of the cylindrical nozzle determined the diameter of the electrolyte jet, and its influence on the machining characteristics was investigated first. Then, the influences of the duty factor and frequency of pulse voltage on the machining process were investigated to improve the machining accuracy. Finally, tungsten micro-rods with high aspect ratio were fabricated by translating the electrolyte jet on the surface of rod workpiece.