不銹鋼表面電解拋光技術研究

The Investigation of Electropolishing Technique for stainless Steel Surface

賴建璋(Jian-Jang Lai)

指導教授 ： 李碩仁

元智大學/工程學院/機械工程學系/碩士(2002年)

摘要

隨著在半導體與生醫產業的發展，對工件表面平滑、潔淨與高抗腐蝕能力的需求越來越顯得重要。電解拋光技術的重要性顯得與日俱增，目前電解拋光技術所使用的電解液以Sulfuric acid和Phosphoric acid為主，但是電解液和抗蝕效果兩者之間的關係尚未完整被掌握，由相關文獻可知，目前的電解液須採用CrO3為添加劑，對環境和操作人員影響很大，上述的問題形成發展電解拋光技術的瓶頸。所以本研究旨在探討抗蝕性和電解液間的關係並開發出替代性添加劑的電解液，探討鈍化膜成份和厚度，討論電解液的組成、抗蝕效果和鈍化膜成份、厚度三者間的關係。
本研究以316L不鏽鋼板為陰極和陽極的電極材料，電解液由Sulfuric acid、Phosphoric acid、Glycerin和DI water所組成，依序探討Sulfuric acid、Phosphoric acid比例和Glycerin、DI water的比例對鈍化膜生成的影響，並探討鈍化膜和抗蝕性之關係。首先對電解液組成進行I-V曲線的實驗，找出電解拋光所須的 〝plateau〞區，再對〝plateau〞區內的電流密度和電壓範圍討論，選擇出〝plateau〞區內最適當的電流密度和電壓參數組合。完成上述實驗後，以各組電解液最佳拋光參數進行全因子實驗，完成實驗後，首先進行表面粗糙度和表面金相的量測，再進行抗蝕性和鈍化膜的分析實驗，由上述實驗結果分析拋光後試片表面機械性質和表面化學、電化學性質的改變，並探討電解液組成對表面粗糙度、表面金相的作用及鈍化膜成份和抗蝕性能變化的影響，建立鈍化膜、抗蝕性能和電解液組成間的關係。
除此之外配合SEMI所訂定的規範作為參考標準，發展出低操作溫度且無CrO3添加劑的環保電解液，並且能達到SEMI所訂立之規範。

關鍵字

電解拋光 ； 電化學拋光 ； 316L不銹鋼 ； 鈍化膜

並列摘要

The ElectroPolishing(EP) process is emerging as one of the key technology for the manufacturing of components of the semi-conductor and bio-medical industries due to the requirement of highly smooth, clean and corrosion resistance on the component surfaces. At present, the major compositions of the electrolyte used in the EP process are sulfuric acid and phosphoric acid. However, the mechanisms between the electrolytic constituents and the anti-corrosion capability of the component surface after processed are not fully understood. It has been one of the technological bottlenecks to proliferate this technology. Therefore, it is the focus of this paper to perform a systematic study on the relationship between electrolytic constituents and its anti-corrosion capability to the component surface.
SS 316 stainless steel plates were employed as both anode and cathode metal plates. The electrolyte was composed of sulfuric acid, phosphoric acid, additive and DI water. They were formed into two groups to study the ratios of concentration level between sulfuric acid and phosphoric acid and that between additive and DI water on the forming mechanism of passive film. It was also to study the effect of passive film on corrosion resistance. Experiments were first conducted to investigate I-V curves of various concentration levels of the electrolyte to find out the “plateau” areas that are conditions suited for electropolishing. Detailed experiments were followed using current density as control parameter in order to find out the optimum operating current density and voltage. Finally, time-history experiments were conducted for various electrolyte components to record thickness of passive films vs. time. The test specimens were analyzed for its anti-corrosion capability and compositions of the passive film. ESCA instrument was employed to analyze the composition of the passive film and to estimate its thickness. From these results, the relationship of the electrolytic constituents, vs. under the optimum operating conditions, the composition and thickness of the passive film and the anti-corrosion capability can be established.
Using the SEMI standards as guidelines, an electrolyte that uses much lower concentration level of the sulfuric acid and operates under lower temperature was derived from the experimental results. It is saved to operate and meets all the SEMI specification requirements.

並列關鍵字

Electropolishing ； EP ； Electrochemical Polishing ； SS316L Stainless steel ； Passive films

參考文獻

3.R. S. Treseder, R. Baboian, and C. G. Munger, NACE Corrosion Engineer’s Reference Book, 2nd ed., NACE, 1991.

4.M. Pourbaix, Atlas of Electrochemical Equilibria in Aqueous Solutions, 2nd ed., NACE, Houston, 1974.

5.D. Briggs and M.P. seah, Practical Surface Analysis, Second Edition, Volume1, Wiley, 1992.

9.Charles L. Faust, “Electropolishing — Stainless Steel Part I, ” Metal Finishing, pp.53–56, febreary, 1983.

10.Charles L. Faust, “Electropolishing — Stainless Steel Part II, ” Metal Finishing, pp.35–37, march, 1983.