MSCA - Postdoctoral Fellowships (PF) on "Optimization of extrusion-based additive manufacturing of metal and ceramic parts for biomedical and aerospace applications"

Research project description

Additive Manufacturing (AM) is an increasingly widespread production technology used to directly create a product from its Computer-Aided Design (CAD) model through layer-by-layer material addition. Currently, many AM materials are available. The application range of AM products is highly related to the materials adopted. Even if polymers are the most used AM materials, industrial and academic efforts are increasingly oriented towards the investigation of metal and ceramic AM technologies due to the superior mechanical and thermal properties of the manufactured products.

The most familiar AM processes for metal and ceramic parts are high-energy consuming, expensive to install and maintain and often require an inert gas environment and cooling system during operation. On the other hand, material extrusion additive manufacturing (MEAM) technologies, which are conventionally used to produce polymeric parts, are less commonly used to process metallic and ceramic materials. Nevertheless, among the AM techniques, MEAM promises to be the most cost-effective solution because of the smaller investment costs, the faster building rates, and the greater production flexibility. Up to date, MEAM cannot be used to directly fabricate metallic or ceramic materials characterized by high melting temperatures. However, polymers filled with metal or ceramic particles can be extruded at a temperature higher than the melting point of the binder polymer. The 3D printed part obtained is the so-called green part, from which the polymer binder is removed by a thermal and/or chemical debinding process. The remaining metal or ceramic powders are then joined together through a sintering step to define the brown part, which is characterized by superior mechanical and thermal properties. However, it is only in the very last few years that the use of highly-filled (HF) metal and ceramic filaments has begun to be extensively studied to fabricate parts with significant mechanical and thermal properties. The main materials that can be experimented are: bronze, stainless steel, copper, inconel, zirconia and alumina. These materials are of great interest because of their outstanding resistance to high temperatures, mechanical stresses and wear. The challenge of this research project is to define optimal printing, debinding and sintering parameters to improve the properties of the final parts in terms of porosity, shrinkage, and warping caused by the thermal post-processing, enhancing, at the same time, mechanical behaviour and repeatability of the process. In particular, the project aims at optimizing the 3D printing of some of the above-mentioned HF metal and ceramic filaments by MEAM technologies as well as their post-processing steps. Particularly, the work will be focused on the application of MEAM technology for industrial fields such as biomedical and aerospace. Currently, the most familiar processes used for metal AM are Selective Laser Melting (SLM), Electron Beam Melting (EBM), and Direct Energy Deposition (DED). The most familiar, instead, for ceramic parts are Binder Jetting (BJ) and VAT photopolymerization. The use of MEAM technology would allow a higher degree of flexibility in terms of material selection. In this regard, it will be possible to produce different materials such as metals and ceramics with a single manufacturing technology. However, to support the potential of the MEAM process and its greater flexibility compared to other AM technologies, a great effort is still required for the various materials in the identification, development and fine-tuning of specific printing profiles and tailored heat treatments. At present, most of the studies evidence the potential of the MEAM process applied to metallic materials but few to ceramics. Also, the results are still characterized by low quality and inferior properties from those obtained for the same materials with different fabrication technologies. The working group promoting this proposal has already experimented MEAM technology with some materials, including bronze, stainless steel, Inconel 718 and alumina with very promising results.

The goal will be to extend the technology to other materials that may be of interest for the above mentioned biomedical and aerospace fields. These fields of application, although very different from each other, share the need to use advanced materials (e.g., zirconia, alumina, inconel), inert and capable of resisting in the presence of aggressive environments. However, additional industry sectors can be also included in the potential fields of application.

The feasibility of the 3D printing process and post-processing will be assessed for each of the selected materials. Also, the key parameters with a significant impact on the quality of both the process and the manufactured parts will be identified. Different sets of parameters will be tested and evaluated in terms of density, porosity, tensile properties, and shrinkage after sintering of the parts. Finally, some case studies will be analyzed and the related physical demonstrators will be produced.

Research activities will be supervised by Francesco Tamburrino. He is Assistant Professor at the Department of Civil and Industrial Engineering of the University of Pisa and teaches the following subjects: Material for Design and Physical and Virtual Prototyping. His research activities are mainly focused on additive manufacturing, design for additive manufacturing, post-processing treatments for additively manufactured parts, industrial design, lattice structures, materials science and technology, dental materials. He participated in several academic and industrial research projects and his research activity has been disseminated in international refereed journals and conferences (SCOPUS ID: 57192316209).

The activities will be carried out in the Additive Manufacturing and Rapid Prototyping, and Materials Characterization laboratories. Among the main equipment available there will be different types of additive techniques, 3D scanners, two furnaces for heat treatments, machines for the mechanical characterization of materials, for hardness and roughness testing, a thermal imaging camera, microscopes, etc.

Eligibility criteria

Applicants must have a PhD degree at the time of the deadline for applications (13^th September 2023). Applicants who have successfully defended their doctoral thesis but who have not yet formally been awarded the doctoral degree will also be considered eligible to apply.

At the call deadline, the applicant must have a maximum of 8 years experience in research, from the date of the award of their PhD degree. Years of experience outside research and career breaks will not count towards the above maximum, nor will years of experience in research in third countries, for nationals or long-term residents of EU Member States or Horizon Europe Associated Countries who wish to reintegrate to Europe.

Mobility Rule: The applicant may be of any nationality but must not have resided or carried out their main activity (work, studies, etc.) in Italy (for European Fellowships) or the host organisation for the outgoing phase (in case of Global Fellowship) for more than 12 months in the 3 years immediately before 13^th September 2023.

Application procedure

Expressions of interest must be sent by email to “francesco.tamburrino@unipi.it” no later than June 10^th, 2023 and must consist of two pdf files:

1. Complete and updated CV, clearly demonstrating all eligibility requirements.
2. Motivation letter, maximum one page.