脈衝電流對電解拋光之影響

The Effects of Pulse Current on ElectroPolishing

施博中(Po-Chung Shih)

指導教授 ： 李碩仁

元智大學/工程學院/機械工程學系/碩士(2004年)

摘要

電解拋光反應時，電極會有氣體產生，因而形成許多氣泡附著於電極表面，如未能即時將之排除，將會造成工件表面有孔蝕，形成表面品質的缺陷。
本研究使用的電源為脈衝電流，藉由間歇電流的作用，通電時電極附近的離子將進行反應使得溶液間出現濃度差；在time-off的週期中，電解液中的離子會藉由擴散作用補充所消耗之離子，間隙通道內的電解產物、析氣也藉此充分排出，電解液獲得充分可靠的更新，在time-on時反應可以更順暢進行，使得加工品質得以改善。
經由定性分析之結果，再用統計學變異數分析的方式，將Ra、Rmax和阻抗當作應變數，脈衝參數當自變數作定量分析，找出各參數對於結果的影響。最後用迴歸分析的方式分別找出Ra、Rmax和阻抗的迴歸方程式，期能藉由這三條方程式預測設定範圍內的結果和趨勢走向。
實驗後粗糙度不管定性分析或定量分析均是脈衝電流優於連續電流，此結果和理論的推論相符合。腐蝕測試並沒有很明顯的差異性。迴歸方程式的預測能力在設定預測的範圍內，越接近中間部分所預測出來的結果誤差越小，但就整體來看，可在範圍內預測出整體的趨勢走向。
總括來說，脈衝電流的應用確實可以得到比較好的拋光品質。

關鍵字

電解拋光 ； 脈衝電流 ； 統計 ； 變異數分析 ； 迴歸分析

並列摘要

ElectroPolishing is an electrochemical anodic dissolution process. Many process parameters may affect the final quality. The bubbles of hydrogen and oxygen on the electrodes, especially on the anode, have the most impact on surface quality of the specimen. Bubbles on the anode may tick to the anode resulting surface defects such pitting hole and flow marks. The bubbles in the electrolyte may also create electrical resistance and non-uniform electric field distribution.
In this research, the effects of pulse current supply on electropolishing process were studied. During the time-on period of the pulse current, electrochemical reaction took place near the electrodes creating ionic concentration difference. During the time-off period, the ions in the electrolyte may replenish by diffusion and convection. The reactant and bubbles may also have time to escape. The process may be more stable.
The specimen material was SS316L stainless steel. The experimental variables were pulse width, duty cycle, electrode gap and polishing time. Surface indices such as surface roughness and microscopy photo were used to evaluate their effects.
Summing up the results, the application of pulse current can get the good surface qualitiy than direct current indeed.

並列關鍵字

electropolishing ； pulse current ； statistics ； ANOVA ； regression analysis

參考文獻

25.田昭武，「電化學研究方法」，科學出版社，1984。

2.Charles L. Faust, “Electropolishing II: The practical side,” Metal Finishing, pp.59—63, August 1982.

3.J. E. Labarga; J. M. Bastidas and S. Feliu, “A Contribution to the Study on Electropolishing of Mild Steel and Aluminium Using Alternating Current,” Electrochimica Acta, Vol. 36, No. 1, pp. 93-95, 1991.

4.N. S. Qu; K. C. Chan and D. Zhu, “Surface roughening in pulse current and pulse reverse current electroforming of nickel,” Surface and coatings technology, Volume: 91, pp. 220-224, 1997.

5.Gerhard Ett; Pessine, Elisabete J., “Pulse current plating of TiB2 in molten fluoride,” Electrochimica Acta, Volume 44, Issue 17, April 15, 1999, pp. 2859-2870.