- 學位論文
水溶性介電液於鈦合金放電發色
Coloring Titanium Alloy during EDM Process with Water-Based Dielectric
摘要
本研究是利用去離子水為加工液，並添加不同種類的水溶性化合物對Ti-6V-4Al 鈦合金進行放電加工。在加工進行時，不僅產生高溫的放電火花將工件熔融去除外，還會伴隨著電解反應的發生，使得加工液解離而析出氧分子，與工件表面的鈦分子產生反應形成氧化鈦。此氧化層會造成光的相互干涉而發色，增加美觀之附加價值，且隨著放電電流、放電脈衝時間、工作因子的調變而有所變化。 研究結果顯示不同水溶性化合物的添加不僅能改善工件表面粗糙度外，還會影響表面顏色之變化趨勢。以導電度較低的去離子水與過氧化氫溶液為加工液時，在放電脈衝時間為1μs下，表面有較明顯的色彩且隨著電流的改變而有所不同。以電流1安培之條件所加工的試片呈現紅色，當電流逐漸增加至8安培時，其色彩則轉變為黃色，而當放電脈衝時間拉長時，表面色彩則逐漸混濁不清楚。導電度較高之碳酸氫鈉與氫氧化鈉溶液則有相反地趨勢，在較短的放電脈衝時間下，工件表面的顏色反而呈現灰暗、模糊，而當放電脈衝時間拉長至1000μs時，表面顏色才會呈現黃色。 此方法可在加工中同時進行表面發色處理，不僅可改善工件表面的性質並可提升製程之效率。
並列摘要
In this research, titanium alloy is machined by electric discharge machining (EDM) with different kinds of aqueous solutions addition in deioned water. During the EDM process, the oxygen is produced from the working fluid due to electrolysis phenomenon and then combined with Ti. As the result of this reaction, titanium oxide is generated on the surface of the workpiece. Besides, the machined zone shows different color tone, which can be influenced by the peak current, pulse duration, and duty factor. The experimental results revealed that aqueous solutions addition can not only improve the surface roughness but also affect the color tone. The workpiece machined in deioned water or hydrogen peroxide solution has evident color which changes with the peak current under the pulse duration 1μs. The color tone turn red to yellow when the peak current is increased from 1A to 8A. However, if the pulse duration is enlarged, color become muddy even in the case of small peak current. On the contrary, when using sodium bicarbonate or sodium hydroxide solution as working fluid, the color tone of the workpiece shows muddy without any color tone until 1000μs. By mean of this novel method, the surface coloring treatment could be carried out during the machining process, therefore the efficiency of procedure would be enhanced greatly.