Machining of Molybdenum by EDM-EP and EDC Processes

[摘要] Molybdenum metal (Mo) can be machined with conventional tools and equipment, however, its refractory propertytends to chip when being machined. In this study, the nonconventional processes of electrical discharge machining (EDM) and electro-polishing (EP) have been conducted to investigate the machining of Mo metal and fabrication of Mo grid. Satisfactory surface quality was obtained using appropriate EDM parameters of Ip 3A and Tonmax= 8.51μm) to 0.23μm (Rmax= 1.48μm). Machined Mo metal surface, when used as grid component in electron gun, needs to be modified by coating materials with high work function, such as silicon carbide (SiC). The main purpose of this study is to explore the electrical discharge coating (EDC) process for coating the SiC layer on EDMed Mo metal. Experimental results proved that the appropriate parameters of Ip= 5A and Ton= 50μs at Toff= 10μs can obtain the deposit with about 60μm thickness. The major phase of deposit on machined Mo surface was SiC ceramic, while the minor phases included MoSi2and/or SiO2with the presence of free Si due to improper discharging parameters and the use of silicone oil as the dielectric fluid.

[发布机构] Department of Mechanical Engineering, Tungnan University, New Taipei City; 222, Taiwan^1;Department of Mechanical Engineering, National Central University, Jhong-Li City; 320, Taiwan^2;Department of Mechanical Engineering, Army Academy, Taoyuan City; 32093, Taiwan^3;Department of Mechanical Engineering, National United University, Miaoli; 36003, Taiwan^4

[效力级别] 机械制造 [学科分类] 材料科学（综合）

[关键词] Coating material;Electrical discharge machining;Electrical discharges;Electrolyte flow rates;High work function;Molybdenum metals;Nonconventional process;Silicon carbides (SiC)