Electropolishing of medical-grade stainless steel in preparation for surface nano-texturing

Abstract

The purpose of this work is to investigate the electropolishing of medical-grade 316 L stainless steel to obtain a clean, smooth, and defect-free surface in preparation for surface nano-texturing. Electropolishing of steel was conducted under stationary conditions in four electrolyte mixtures: (A) 4.5 M H 2 SO 4 + 11 M H 3 PO 4 , (B) 7.2 M H 2 SO 4 + 6.5 M H 3 PO 4 , (C) 6.4 M glycerol + 6.1 M H 3 PO 4 , and (D) 6.1 M H 3 PO 4 . The influence of electrolyte composition and concentration, temperature, and electropolishing time, in conjunction with linear sweep voltammetry and chronoamperometry, on the stainless steel surface was studied. The resulting surfaces of unpolished and optimally polished stainless steel were characterized in terms of contamination, defects, topography, roughness, hydrophilicity, and chemical composition by optical and atomic force microscopies, contact angle goniometry, and X-ray photoelectron spectroscopy. It was found that the optimally polished surfaces were obtained with the following parameters: electrolyte mixture A at 2.1 V of applied potential at 80°C for 10 min. This corresponded to the diffusion-limited dissolution of the surface. The root mean square surface roughness of the electropolished surface achieved was 0.4 nm over 2×2 μm 2 . Surface analysis showed that electropolishing led to ultraclean surfaces with reduced roughness and contamination thickness and with Cr, P, S, Mo, Ni, and O enrichment compared to untreated surfaces.

Electrochemical polishing as a 316L stainless steel surface treatment method: Towards the improvement of biocompatibility

“…On the other hand, surface brightening (i.e., micro-smoothing) refers to the exclusion of surface roughness height lower than 1 µm, which is comparable to the wavelength of visible light, thus leading to a reflective mirror-like surface [16,22,23]. Surface brightening occurs due to the suppression of the influence of the metal/alloy microstructure, surface defects and crystallographic factors on the dissolution process [13,24]. As a result, random removal of atoms from the metal results in a quite smooth surface topography.…”

Electropolishing Characteristics of Stainless Steel for Industrial Application

“…전해연마는 금속 표면의 마무리 공정으로 주로 사용된다. 전해연마는 기계연마와 달리 가공변질 층 이나 버(burr), 미세한 연마 홈과 파티클이 발생하 지 않아 의료용 기구, 반도체 장비, 식품위생용품, 정밀화학 장치 등 많은 분야에서 사용되고 있다 [2][3][4]. 전해연마는 표면을 매끄럽고 광택이 나게 하는 효과 외에도 내식성 향상, 표면 응력 제거, 디버링 등이 있다.…”

“…전해연마는 표면을 매끄럽고 광택이 나게 하는 효과 외에도 내식성 향상, 표면 응력 제거, 디버링 등이 있다. 특히 전해연마에 사용되는 스테인레스 스틸은 전해연마에 의해 크롬산화층 형성으로 내식 성이 필요한 식품 및 의료용 제품, 반도체 및 화학 약품 제조 장치 등에 많이 사용된다 [3][4][5]. 전해연마 와 관련한 다양한 연구가 진행되어 오고 있으며, 이 러한 연구들은 주로 금속종류, 전해액 조성이나 전 류밀도 변경에 따른 특성과 표면 변화에 관한 것이 다 [2,3,5,6].…”

“…전해연마 와 관련한 다양한 연구가 진행되어 오고 있으며, 이 러한 연구들은 주로 금속종류, 전해액 조성이나 전 류밀도 변경에 따른 특성과 표면 변화에 관한 것이 다 [2,3,5,6]. 또한 전해연마 특성 연구 시 사용하는 양극 평판 시편 크기는 가로, 세로가 1 cm × 1 cm나 직경이 1 cm 이내이고, 극간거리는 0.5 mm, 1 mm, 2 mm 등 1 cm 이내가 대부분이었다 [3][4][5][6][7][8] …”

Anti-Corrosion Application of Poly(indole-5-carboxylic Acid) Coating on Low Nickel Stainless Steel in Acidic Medium

“…The largest part of stainless steel equipment failure are caused by chloride ions, particularly in cooling water systems the pitting and crevice corrosion are still the serious problems of stainless steel 3 . Surface treatment procedures such as electro polishing, low temperature nitridization and passivation have been used to enhance the resistivity of the metals [4][5][6][7] .The increasing application of the RESEARCH ARTICLE stainless steel to improve efficient and environmentally complicated method, corrosion and either inhibitors or conducting polymer coating [8][9][10][11][12] . In recent times, conducting polymers have received considerable attention as corrosion protective coatings for oxidizable metals.…”