| 摘要: | 電化學加工是屬於非傳統加工的一種，利用低電壓、高電流使材料以離子狀態快速溶解，而達到加工目的的加工方法，其優點為設備成本低廉、刀具不易損壞、工件表面不含殘留應力等，且複雜的工件也能輕易地加工。在過去文獻當中，對於材料的電化學特性資訊較不足，因此本文旨在建立常用金屬材料的電化學特性資料庫，以供未來業界做參考。
本實驗分成三個部分：（一）利用恆電位儀量測電流-電壓曲線圖（I-V Curve），探討材料的電化學特性。（二）靜態電化學加工量測，利用電解液側向流場，通電5分鐘，紀錄電流、移除量並計算出電流密度。（三）加工後工件表面量測，包括工件表面結構狀況以及表面元素。並建立常用金屬電化學特性資料庫。探討的金屬工件包括不鏽鋼、模具鋼、高速鋼、構造用合金鋼、鈦合金、鎳合金、哈氏合金、磷青銅以及碳化鎢等等。本研究採用兩種中性的電解液硝酸鈉（NaNO3）與氯化鈉（NaCl）進行電化學加工。
由實驗結果顯示，在氯化鈉電解液中加工，電流密度比在硝酸鈉電解液中高，陽極工件移除量也較多，但是表面精度與粗糙度方面，利用氯化鈉電解液加工卻比較差。含鎢或銅的材料，因材料硬度較硬且表面易有鈍化層生，碳鋼類的材料在氯化鈉電解液中易有黑層（黑色鬆散的粒子層），皆會阻礙加工。鈦金屬材料在中性電解液中，加工品質均不佳，加工過程會有雜質稀出而造成金屬表面有許多孔洞。;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. |
