Impact of different alloying additives and pre-treatments on the anodising behaviour of AA2007
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- 作者：C. M. Schlö ; gl and H. Antrekowitsch
- 刊名：Surface and Interface Analysis
- 出版年：2016
- 出版时间：August 2016
- 年：2016
- 卷：48
- 期：8
- 页码：939-945
- 全文大小：437K
- ISSN：1096-9918
文摘
Most of the common alloying additives in wrought aluminium alloys have a strong impact on the anodising process and the aluminium oxide surface layer produced. Depending on their concentration, appearance in the aluminium matrix and electrochemical behaviour, they lead to different colouring and optical appearance of the aluminium oxide, respectively. These elements could also have an impact on the layer thickness and affect their regularity of them. In most cases, the influence of corrosion resistance and surface hardness is unavoidable. Therefore, the aim of this work is to analyse and illustrate the impact of different aluminium grain refiners (like TiB2 and Zr) and chip breaking additives (like Bi, Sn and Pb) on the anodising behaviour of AA2007 aluminium. Hence, several AlCuMg alloys with varied amount of these substitutes were produced and heat treated. To avoid and discover interdependencies of alloying elements, materials with only one alloying element (like Al-1%Ti) were also produced. Additionally, different chemical and mechanical pre-treatments were compared. Variations in current densities during the anodising processes completed the investigation. In the experimental part, the different materials were mechanically (e.g. turning, milling and polishing) and chemically pre-treated (in NaOH and/or HNO3), anodised in sulphuric acid and hot sealed in a pilot plant. After the whole anodising process, cross-section preparations in combination with scanning electron microscopy/energy dispersive X-ray spectroscopy analysis helped to investigate the impact of single alloying additives, reflect the effects of different pre-treatments and show the results of variation in anodising conditions. Copyright