Aston University receives EPSRC grant to improve liquid metal casting

The mathematical method aims to help prevent lightweight aluminium alloys corroding - or oxidating - very quickly when first exposed to air.

The researchers said that, within the transportation sector, steel is gradually being replaced by ‘functionalised energy-efficient lighter alloys’, with the aim of lessening the CO2 emissions of the metallurgy industry, as less fossil fuel is burnt when moving a lighter product.

However, although these replacement lighter parts do not rust like steel, they oxidise very quickly when first exposed to external ambient conditions.

A thin oxide film develops on the surface of the metal once exposed, which under regular usage conditions, ensures the metal will not corrode. However, during the casting process, when the aluminium is still in a molten state, this thin oxide film can be encapsulated into the bulk of the liquid metal flow.

It has been shown that this encapsulation process, which can happen many times over, necessarily leads to the embedding of these oxide films within the main body of the finished product, thus diminishing their quality and lifespan.

In a statement, Dr Paul Griffiths, senior lecturer in applied mathematics at Aston University, said: “The aim of this investigation is to develop a mathematical model that accurately captures the two-way coupling between a liquid metal flow and the oxide layer above, with the latter behaving as a non-Newtonian liquid/gas interface.

“The objective of this project is to describe both the surface characteristics - velocity and shear profiles - as well as the important effects of surface curvature.

“The benefit of a more appropriate mechanical model for the oxidised surface of a melted metal flow would lead to a better understanding of the encapsulation process which affects the alloy.”

Aston University said the model will be validated and verified against current experimental observations, with the aim for the results to provide new insights as to how this oxidisation process can be controlled in a practical setting.

A better knowledge of this could specifically improve the emerging processes of 3D printing and additive manufacturing (AM) of lighter metals.

The research, beginning in April 2024, will be partnered by the Grenoble Institute of Technology (INP).