SEE MORE MAKE MORE: Secondary Electron Energy Measurement Optimisation for Reliable Manufacturing of Key Materials

Lead Research Organisation: University of Sheffield
Department Name: Materials Science and Engineering

Abstract

Additive manufacturing (AM), or 3D printing, is an exciting new form of industrial production that promises to revolutionise sectors as diverse as healthcare, energy, aerospace, and transport. By allowing stronger, lighter, and more complex components to be formed from a variety of materials, AM will play a critical role in meeting emerging technological needs over the coming decades. One area in which AM is already generating huge excitement is in bone tissue engineering for the production of implants for patients who have degenerative diseases or who need, for example, facial reconstruction following an accident or cancer. However, making large and load-bearing implants reproducibly is still a significant challenge. AM theoretically allows the reproduction of extremely complex geometries while also accounting for variation in the structural, mechanical, and cellular properties of bone tissue. Such flexibility will be essential to produce load-bearing 3D printed bones that have the strength to replace metal-based implants but which also mimic intricate vascular networks.

Much of the flexibility of AM arises from its use of composites which combine the desirable properties of several different materials. Increasingly, in a form of AM that uses a laser to continually melt (sinter) the composite material, polymers are mixed with nano-carbon to make materials stronger and more conductive. However, an outstanding challenge in the field is to ensure that the carbon is evenly distributed throughout the matrix polymer to produce printed components with reliable properties. We also need to be able to monitor nanocarbon distribution in real time during AM which will require new, innovative methods of advanced metrology.

Using the unique facilities and experience of our team, we will address these engineering challenges to provide the AM community with a step-change in their ability to produce bespoke high-quality components. To do this, we will build on significant breakthroughs we have recently made in developing new methods of hyperspectral imaging, that is, techniques that allow us to map the chemical and structural properties of a material and how these change under different conditions. Using electrons as a probe provides information on how nanocarbon particles interact with each other and their environment, for example, when heated with a laser. Such information is critical to optimise AM processes but, because this technique operates at the nanometer level, it is not practical for monitoring whole components whilst they are printed. For this, we will use another method of hyperspectral imaging based on thermal emission, similar to how we can measure temperature from the familiar glow emitted by hot coal in a fire. By combining these methods of electron imaging and thermal emission detection, we will be able to control how nanocarbon is distributed throughout a composite material and how this affects critical macroscale properties such as porosity, conductivity, strength, and surface finish. Together, this new hyperspectral imaging framework will benefit researchers and industry using AM for various applications leading to gains in cost, yield, energy efficiency, and lifetime.

Once our framework is established, we will demonstrate its effectiveness by applying it to AM of bone tissue scaffolds from a novel composite we will develop containing nanocarbon mixed with a biocompatible polymer. By optimizing the laser heating process and controlling nanocarbon distribution and state, we will make scaffolds that are fit for clinical use, as validated through tests with our industry partner Lucideon. Other partners include NPL, ASTeC, YPS, Spintex, and FBK who will enhance the impact of our project through applications in Li ion batteries, pharmaceuticals, energy materials, and accelerator technologies.

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