Light-based multi-material 3D printing of ceramic composites

About the Project

This project is part of cohort 3 of the EPSRC CDT in Developing National Capability for Materials 4.0, with the Henry Royce Institute.

A number of key technologies are locked behind ceramic materials innovation. Nuclear fusion require plasma facing shields that needs to be strong and tough, but also temperature resistant and good neutron attenuator, while solid state battery electrolytes must be fast ionic conductors and resistant to crack induced by lithium dendrite. While we are actively searching for compositions that present all these requirements, we can also leverage a material’s microstructure to solve some of them. Ceramic composites are now being developed for these applications and more. We have at our disposal architectures based on reinforcements such as long-fibres and particulates, and their fabrication relies on first producing the reinforcements and then surrounding/mixing them with a different material. Other architectures, based on metamaterials or natural materials design, rely on more complex and regular architectures that cannot be achieved by conventional methods. These designs hold the key to combination of toughness, stiffness and strength beyond the more established composite microstructures, for instance strut/shell-based architecture for lightweight and strong components, or interlocking geometry for their resistance to fracture and impact. In theory, composites with interlocking elements can be used to add a strain hardening effect in brittle materials, reaching toughness and strain at failure beyond any other concepts. They will remain theoretical until we can develop a process capable of making these with a high spatial resolution. Indeed, ceramic strengths are highly size-dependent so making strong composites demand controlling their microstructure and composition at the smallest scale to exploit this effect.

Our fabrication design space remains limited and so is our exploration of microstructure-properties relationships, a limitation multi-material 3D printing can start solving. Digital Light Processing (DLP) specifically controls the curing of light-sensitive inks with a spatial accuracy in the tens of micron range within centimetre-sized 3D shapes for the best printer. Adding the capacity to have multiple inks unlock the possibility to make and study rapidly a series of composite architectures, with different level of regularity and 3D complexity.

Our group is currently building a DLP printer, using a UV-projector reaching 18µm/pixel and two robotic platforms capable of linear movement micron-level accuracy, one platform being responsible for switching between inks. These capabilities, once improved in the first part of this project, will allow us to explore microstructure/properties relationship so far out of reach. We will start with simple brick-and-mortar architectures and expand to more complex design with elements that can interlock during fracture or impact.

The goal of this project will thus be first to: (i) to develop the printer capabilities further, (ii) to use colloidal processing to develop ceramic inks that can be printed and (iii) explore the microstructure to strength/toughness relationships in interlocking composites microstructures.

The first part will be to add a sensor to the printing platform to measure the peeling forces and add a feedback loop to the printing program to limit them, as well as adding a cleaning station to avoid the mixing of the inks during printing. The second goal will be centred on using model ceramic inks that allows for an easy final processing (debinding and co-sintering) and visualisation of the microstructure after printing. The final goal will be to design composites microstructure and study their toughness using mechanical testing, comparing them with more traditional composite microstructures. The fidelity with which we can design these microstructures will be monitored and we will use different minimisation algorithms to adapt iteratively the printing and converge to the desired microstructure, with the possibility of adding an image-based machine learning model to learn from these results and expand to other design/inks.

This new manufacturing method will not be limited to structural materials and the designs targeted by this project but will instead be used in the future to help fabricate and explore rapidly a large design space of complex architectures for multiple applications.

Funding Notes

This is a fully-funded project, part of cohort 3 of the EPSRC CDT in Developing National Capabilities in Materials 4.0. The studentship covers home fees, a tax-free stipend of at least £20,780 plus London allowance if applicable, and a research training support grant.

Enquiries

For general enquiries, please contact doctoral-training@royce.ac.uk.

For application-related queries, please contact a.neri14@imperial.ac.uk.

If you have specific technical or scientific queries about this PhD, we encourage you to contact the lead supervisor, Dr Florian Bouville (f.bouville@imperial.ac.uk).

Application Process

Please note that each partner of the CDT in Materials 4.0 will have its own application process.

The Materials 4.0 CDT is committed to Equality, Diversity and Inclusion. We strongly encourage applications from underrepresented groups.

Application Web Page

https://myimperial.powerappsportals.com/

Click on 'Make a new application', and then type 'Materials 4.0' in the search box.