Confinement of the Removal in Jet-Electrochemical Machining of Solid-state Sintered Silicon Carbide

Solid-state sintered ceramics of silicon carbide (SSiC) offer excellent wear and corrosion-resistance for numerous applications in harsh environments with high temperatures, in aggressive chemicals or at high mechanical loads with strong abrasive impacts. Specific material characteristics such as its extremely high hardness and high heat conductivity, which represent positive or aspired application properties, however, interfere with machining characteristics. Particularly, surface structuring of SSiC in a micro-scaled is challenging due to extremely high tool wear in mechanical milling, drilling and grinding. Ablation techniques such as electrical discharge machining and laser-beam machining require excessive machining times or cause negative thermal impacts. Electrochemical machining (ECM) using a continuous jet of electrolyte (Jet-ECM) is therefore analyzed in this study to create removal shapes with micro-scaled lateral expansions. According to previous analyses, that indicated successful removals with Jet-ECM in millimeter-scale, a planar sample surface of SSiC was successfully machined with a NaOH-electrolyte at voltages exceeding 230 V. The reduction of the nozzle diameter offered micro-scaled removals with diameters significantly below 300 µm. However, a reduction of the working gap to a critical value of 300 µm was necessary, which caused electrical discharges, even if the dielectric strength of the surrounding air was not achieved. The successful achievements also reveal the need for further investigations, which are required to keep the dissolution process ongoing for continuous micro-shaping with controllable results.