Title: Cell compatibility of Co-Cr-Mo alloy treated with electrolytic in-process dressing grinding/thermal oxidation hybrid process

Authors: Ihori Hiraga; Mihoshi Hamada; Jun Komotori; Masayoshi Mizutani

Addresses: Graduate School of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama-shi, Kanagawa 223-8522, Japan ' Graduate School of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama-shi, Kanagawa 223-8522, Japan ' Department of Mechanical Engineering, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama-shi, Kanagawa 223-8522, Japan ' Department of Mechanical Systems and Design, Tohoku University, 6-6-01 Aramaki-Aza-Aoba, Aoba-ku, Sendai, Miyagi 980-8579, Japan

Abstract: In order to improve cell compatibility of the Co-Cr-Mo alloys, an electrolytic in-process dressing (ELID) grinding and thermal oxidation (TO) hybrid process was performed. Surface roughness of specimens was measured by a non-contact type three-dimensional profilometer, and the elemental analysis of the treated surface was performed by a glow discharge optical emission spectrometer (GD-OES). To evaluate cell compatibility, a cell culturing assay was carried out. The surface roughness of all treated specimens was lower than that of the sliding parts of commercially applied artificial hip joints. Elemental analysis showed that the oxygen content from the surface of specimens treated with TO increased significantly with the increase in treating temperature. In particular, a region with a lower content of cobalt was observed at the ELID/TO hybrid-treated specimens with treated temperatures higher than 500°C. Moreover, the ELID/TO hybrid-treated specimens showed better cell compatibility than other specimens. This was because the levels of cobalt ions released from ELID/TO hybrid-treated specimens was lower than that of the others.

Keywords: biomaterials; artificial hip joints; Co-Cr-Mo alloys; cobalt; chromium; molybdenum; electrolytic in-process dressing; ELID; grinding; thermal oxidation; cell compatibility; surface modification; metallic ions; surface roughness; surface hardness.

DOI: 10.1504/IJNM.2013.057592

International Journal of Nanomanufacturing, 2013 Vol.9 No.5/6, pp.486 - 495

Available online: 13 Nov 2013

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