Mon, 22 July, 2024
NSIRC PhD student, Francesco Careri has had a paper published in the journal of Surface and Coatings Technology.
The paper, ‘Plasma Electrolytic Oxidation (PEO) as Surface Treatment for High Strength Al Alloys Produced by L-PBF: Microstructure, Performance, and Effect of Substrate Surface Roughness,’ was co-written with input from TWI’s Dr Raja Khan and Dr Alessandro Sergi as well as Dr Pavel Shashkov from Cambridge Nanolitic Ltd and Prof Moataz Attallah from the University of Birmingham.
Additive manufacturing of aluminium alloys has developed to the point whereby it is replacing the use of cast and wrought components in industries such as space, aerospace and automotive. However, these alloys suffer from poor corrosion and wear resistance when operated at high temperatures or in critical environments.
This paper discusses research into the use of the surface treatment, plasma electrolytic oxidation (PEO) also known as micro arc oxidation (MAO) and electro chemical oxidation (ECO) on two high strength aluminium alloys, i.e., AlSi10Mg and A205 (also known as A20X) processed via laser powder bed fusion (L-PBF) additive manufacturing technique in order to enhance corrosion resistance and wear performance of the materials.
The PEO coating was produced on two different surface conditions (as-fabricated and polished) and characterised in terms of morphology and composition through scanning electron microscopy (SEM) and digital microscope analysis.
Once the coating had been applied, it was tested for porosity and hardness to assess the difference between the coated materials and the virgin material. Friction and corrosion tests were also undertaken and evaluated against the results for the non-coated aluminium materials.
The results showed an increase in hardness with the PEO coating as well as large increases in the materials’ wear and corrosion resistance performance when coated. It was also demonstrated that the presence of the oxidised layer improved the mechanical properties of the surface and, accordingly, the general performance of the material. Furthermore, performing a surface polishing treatment before PEO treatment helped to further increase the corrosion resistance and tribological properties of the L-PBF aluminium alloys.
To find out more, you can read the paper, in full, here.