ArcHIDep, the possible future of “impossible materials”

The European Research Council (ERC), the body of the European Union that rewards talented scholars engaged in cutting-edge research, has awarded an ERC Consolidator Grant 2022 to Sara Bagherifard, a researcher in the Department of Mechanics, for the research project ArcHIDep. The project was selected from over 2600 presented at ERC. An excellent result, considering that only 11.8 percent of the projects presented were funded this year. We met Sara Bagherifard to talk with her about finding her.

Sara Bagherifard
Sara Bagherifard, researcher of the Mechanics department of the Politecnico di Milano, winner of the ERC Consolidator Grant 2022 with the ArchiDep project.

ArcHIDep: a revolutionary solid state deposition system to obtain heterogeneous materials. So, I would like to start with a general question: What is cold spray and how does it work? 

Cold spray is an emerging solid state deposition technique that accelerates small powder particles to supersonic velocities using a compressed gas. Upon impact to a substrate, the high kinetic energy of the particles will dissipate into plastic deformation providing the condition for bonding of the particles to the substrate and eventually to each other to form a build-up. The intrinsic characteristic that distinguishes cold spray from the other deposition techniques is its low working temperature, that offers a unique flexibility for depositing materials that are sensitive to temperature and oxidation. Cold spray has been traditionally used for protection coating in non-load-bearing applications, but our recent research has confirmed its high potential not only for coatings but also for additive manufacturing of structural components.

With your project ArcHIDep, you are one step ahead of the state of the art on cold spray; what elements or steps does it add? What limits does it transcend? 

ArcHIDep takes advantage of the unique opportunities offered by cold spray including the high deposition rate, the high deposition efficiency, and most importantly, the possibility of mixing materials with different chemical, microstructural or thermo-mechanical properties. By establishing a design framework based on analytical, experimental, and numerical approaches, ArcHIDep will make it possible to implement multiscale heterogeneity and exploit the synergy between the heterogeneity indexes designed at multiple length scales to tailor the continuum-level behavior of the integrated structure towards unprecedented functionalities.

What is the goal of your research looking 5 years ahead?

Using heterogeneity as an extra Degree of Freedom, by the completion of this project I envision to have a framework that potentially fills the gaps in Ashby design space and can offer new material properties and functions that go beyond the rule of mixture. Manufacturing is a multibillion industry relying on use of materials, transportation and energy. The new design and manufacturing scheme that will be developed in ArcHIDep will have notable impact in terms of sustainability through a more intelligent use of raw materials and increased service lifetime, besides enhancing the ability to obtain highly customized structures.

What could be an example of an actual object achievable with this project?

Spatial regulation of composition and architecture in one single component can efficiently generate a variety of unique site-specific properties potentially in every branch of technology. This can be especially an ideal solution when we are dealing with multiple conflicting requisites in a component subjected to heterogeneous states of stress, strain or temperature. For instance, customized arrangement of dissimilar lightweight materials architected in a way to offer modulated thermal expansion and thermal conductivity can minimize thermal stresses (caused by a gradient of 1000 K over few mm thickness) in space propulsion thrusters and thus substantially expand their max burn and lifetime.

The European Research Council (ERC) funded his project, chosen from over 2600 proposals received. A great result. What does this recognition mean for you and your work? 

The importance of ERC funding is the freedom and flexibility it offers for exploring high risk-high gain ideas that would be normally more difficult to explore, using the other funding programmes. This grant gives me the opportunity to expand my research area and get access to resources that otherwise would have been inaccessible. Apart from that, this grant for me is a meaningful recognition of the scientific achievements and the efforts made in my career.

Sara Bagherifard - Politecnico di Milano
Sara Bagherifard – Politecnico di Milano

What is the motivation behind your work on innovation in materials?

Continued increase in demand for superior performance while seeking sustainable and material-efficient solutions in many different sectors, have brought significant attention to the need for structures with distinctively customized qualities. However, implementation of tailored design to address these contrasting requisites is still out of our reach. Despite the great promise and expectations, current additive manufacturing technologies are not yet offering the flexibility required to gain the desired control on composition, inner arrangement and outer shape. Offering a design and manufacturing framework that can bridge these gaps have urged me to develop the idea of this project.

Was this the job you imagined doing as a child? How did you get involved in STEM subjects and research?

When I was a child, I liked to pursue my mum’s job, that is teaching. As I grew older, I changed my mind and got more interested in Math and Science. When it was time for me to select a major at University, I started to narrow in on engineering specifically mechanical engineering since it allowed me to use and develop math, science, and problem-solving skills. I was passionate about the idea of designing and constructing functional structures and systems that people can use even in every-day life. The attitude towards girls in STEM can be intimidating but, in that case, I must acknowledge the impact of STEM activities sponsored by the educational system at the time, which helped me with my choice at the university. Well, now I can say I selected a career that is combining design and development, with my passion for research.

There is a lot of talk about the gender gap in many areas, including research: do you feel this “gap”?

Unfortunately, yes! Female scientists are underrepresented, often not taken seriously or stereotyped in STEM departments in academia. It is harder for us to reach higher academic ranks, despite performing just as well as male colleagues. For my personal case, add being a foreigner on top of that bringing in multiple other issues requiring extra energy and effort. Despite the increased awareness of the lack of gender equity and any type of diversity in academia, implicit bias still exists. Changes will need real effort on educating against any diversity biases and improving academic climate.

What would you recommend to a young researcher who wants to move in the direction of this type of research? 

Shaping a novel hypothesis-driven idea and preparing the ERC proposal require considerable time and effort and can be quite overwhelming. This tough competition requires an extensive and carefully planned long-term preparation. You need to build up solid knowledge and expertise in your field and demonstrate a proven track-record of research and management abilities; this continuing preparation paired with dedication and determination will increase your chances to be recognized among the high-quality candidates.