Politecnico di Milano researchers work on new materials for space engines

The ATLAS project gets underway, its aim being to develop new materials that perform in extreme environmental conditions, enabling important progress in design and construction of space propulsion systems.

ATLAS (Advanced Design of High Entropy Alloys Based Materials for Space Propulsion) is coordinated by the Politecnico di Milano as part of the Horizon 2020-SPACE programme and it has received three million euro in funds. Prof. Mario Guagliano is the project manager.

One of the biggest problems linked to space missions is the need to build systems that will function without failure in extreme environments, at temperatures varying from way below zero to peaks of hundreds of degrees.

Propulsion systems in particular are subject to severe stress and have to be big enough to adequately resist in these conditions, a factor that clashes with a parallel need for minimum weight. The solution this problem is the development of ad hoc materials that combine all the properties requested and maintain them in extreme environments, such as those in which space missions take place.

The ATLAS project aims to develop new materials based on High Entropy Alloys, (HEAs), able to simultaneously guarantee low density, high strength and ductility, oxidation resistance, and good stress and deformation properties in extreme conditions. High entropy alloys are a relatively new class of materials identified as a possible replacement for superalloys in extreme applications. However, they are not yet widely used due to unresolved aspects that ATLAS intends to address.

Adopting a multidisciplinary approach, ATLAS will design and realise composite materials, using high entropy alloys as the matrix and ceramics to strengthen. This will produce materials able to optimise the properties required for use in the combustion chambers of space propulsion systems.

For construction of coverings and components in these materials, two different yet complementary additive manufacturing techniques will be used, one thermal (PBF, Powder Bed Fusion), the other dynamic, Cold Spray.

Specifically the latter, a high-pressure cold-spray unit has been installed in the Department of Mechanical Engineering laboratories at the Politecnico di Milano.

Cold spray is a powder coating deposition technique that, unlike other technologies, exploits kinetic energy and does not required the powders to be melted.

The cold spray process is based on the acceleration of metal powders to supersonic velocities, a mechanism that causes the powders to adhere to the surface on impact with the substrate, gradually forming an increasingly thicker coating. The only property required to ensure this adhesion is plastic deformation of the material, which must therefore be ductile. This makes the cold spray process a particularly attractive solution as it is applicable to most metals, as well as making possible the development of new materials based on mixtures of different powders.

In addition to the Politecnico di Milano, the ATLAS consortium includes the Deutsches Zentrum für Luft und Raumfahrt (DLR), the German aerospace research centre, the University of Derby (UK), and the hi-tech SMEs Arceon (NL), Dawn Aerospace (NL), Questek Europe (SE), Tisics (UK), and YourscienceBC (UK).

This article was first published on May 31 by Politecnico di Milano.