| dc.description.abstract | Electrochemical machining (ECM) is one of the non-traditional manufacturing process which works on the low voltage and high current to dissolve materials rapidly in ion states. It has advantages such as inexpensive machining equipment, little or no tool wear, no residual stress on the work piece surface, and competence for machining complex geometries. In previous studies, it had not enough information about electrochemical characteristics of materials, so the aim of thesis is to establish the electrochemical characteristics for common metallic materials. It can be used as reference for industry in the future.
This article can be divided into three parts, namely, (1) Using autolab to measure current-voltage curves (I-V curves), and investigated electrochemical characteristics of materials. (2) Static electrochemical machining measurement: discharged for 5 minutes and recorded the current, material removal amounts and calculated the corresponding current density. The electrolyte flows into the machining area in the side direction. (3) After machining the work piece surface condition was measured, including surface structure and elements contained. The electrochemical characteristics and machining work database were established. Different kind of materials were performed, including stainless steels, pattern die steels, high speed steels, chromium molybdenum steels, titanium alloy, nickel alloy, Hastelloy alloy, phosphor bronze, and tungsten carbide alloy. They were manufactured in NaNO3 and NaCl electrolytes.
Experimental results show that, most of the materials in the NaCl electrolyte, the current density and material removal amount are larger than that in the NaNO3 electrolyte. However, the surface precision and roughness are poor in NaCl electrolyte. The materials contained copper or tungsten are high hardness and the passivation layer will be formed on the surface. The black film, also formed on the surface in NaCl electrolyte and materials contained carbon steels, will cause machining difficult. The materials contained titanium have poor machining quality in the neutral electrolytes, where the particles will be dissolved during the machining process and result in pitting phenomenon on the work piece surface. | en_US |