Heat treatment condition of EN AW-7075 influencing the anodic oxidation process and coating properties

20th Chemnitz Seminar on Materials Engineering - 20. Werkstofftechnisches Kolloquium

Morgenstern, R.^1 ; Scharf, I.^1 ; Lampke, T.^1

Institute of Materials Science and Engineering, Chemnitz University of Technology, Chemnitz

09125, Germany^1

关键词: Age-hardenable aluminium alloys;    Anodic oxide layers;    Field emission electron microscopy;    Heat treatment conditions;    Instrumented indentation;    Light-weight constructions;    Microstructure and properties;    Oxalic acid solution;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/373/1/012021/pdf
DOI  :  10.1088/1757-899X/373/1/012021

来源: IOP

【 摘 要 】

The age-hardenable aluminium alloy EN AW-7075 exhibits outstanding specific mechanical properties and therefore offers a high potential for lightweight construction. Anodising in aqueous oxalic acid solutions is suitable to produce a protective oxide ceramic conversion layer on this alloy. This study examines the influence of the precipitation state of the substrate alloy on microstructure and properties of anodic oxide layers. Therefore, EN AW-7075 sheets in the heat treatment conditions T4, T6 and T73 were anodized in 0.8 M oxalic acid solution at constant voltage. The current efficiency was determined on the basis of the electrical charge quantity, coating thickness and coating mass. Instrumented indentation tests were applied in order to evaluate the coating hardness. The microstructure of the anodic oxide layer was illustrated using field emission electron microscopy. It was shown that the current efficiency strongly depends on the heat treatment condition.