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Advances in Materials Science and Engineering
Volume 2017, Article ID 2416821, 12 pages
https://doi.org/10.1155/2017/2416821
Research Article

Investigation of the Scanning Microarc Oxidation Process

1School of Mechanical, Electronic and Control Engineering, Beijing Jiaotong University, Beijing 100044, China
2Mechanical Engineering Department, Marquette University, 1515 West Wisconsin Avenue, Milwaukee, WI 53201 1881, USA

Correspondence should be addressed to Jianmin Han; nc.ude.utjb@nahmj

Received 24 January 2017; Revised 21 May 2017; Accepted 28 May 2017; Published 20 June 2017

Academic Editor: Ming-Xing Zhang

Copyright © 2017 Lingqin Xia et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Scanning microarc oxidation (SMAO) is a coating process which is based on conventional microarc oxidation (MAO). The key difference is that deposition in SMAO is achieved by using a stainless steel nozzle to spray an electrolyte stream on the substrate surface as opposed to immersing the workpiece in an electrolyzer. In the present study, SMAO discharge characteristics, coating morphology, and properties are analyzed and compared to results obtained from MAO under similar conditions. Results show that MAO and SMAO have comparable spark and microarc lifetimes and sizes, though significant differences in incubation time and discharge distribution were evident. Results also showed that the voltage and current density for MAO and SMAO demonstrate similar behavior but have markedly different transient and steady-state values. Results obtained from coating A356 aluminum sheet show that oxide thickness and growth rate in SMAO are strongly dependent on interelectrode spacing and travel speed. Analysis of the SMAO coating morphology and structure showed that a denser and slightly harder layer was deposited in comparison to MAO and is attributed to reduced porosity and increased formation of α-Al2O3. Preliminary results indicate that SMAO represents a viable process for coating of aluminum surfaces.