Formation and Characterisation of Duplex Anodic Layers

There is a significant movement within many large industries such as automotive, aerospace, architectural, marine etc to replace chromate based surface treatments with an environmentally friendly alternative. Chromates are currently being targeted for elimination from manufacturing practices due to their carcinogenic nature. In order to navigate impending restrictions from the European chemicals agency on chromate based compounds, a new surface treatment is required for aluminium alloys to replace chromic acid anodising (CAA).
Anodising processes for aluminium involve the electrochemical formation of nanoporous oxide layers in usually acidic electrolytes and is used extensively for aluminium to impart elevated corrosion and mechanical properties to the surface. A potential replacement for CAA is based on duplex anodising processes. The duplex anodising process involves a double anodisation to achieve a surface layer that exhibits optimised adhesion properties with a second base layer that provides corrosion resistance. The use of duplex anodic layers is growing in industry with patents filed by companies such as Airbus and Bombardier. CREST researchers have also patented a duplex anodising process that offers unique features over the state of the art. This PhD programme proposes to further develop, optimise and characterise the pre-treatment steps and duplex anodising process for various aluminium alloys. The electrochemical formation of the duplex anodic layers will be monitored and tailored. The processing parameters will studied to determine the effect on final film properties such as nanoporous structure, corrosion resistance, adhesion properties, fatigue resistance and surface hardness.
The candidate will utilise a range of electrochemical and accelerated corrosion and weathering tests to analyse the performance of the layers produced. High resolution electron microscopy and advanced spectroscopic techniques will be used to analyse the layers formed during the body of work.


Student requirements for this project
2.1 BSc in Chemical Sciences, Materials Science or related