Shattering a 10000-Year-Old Ceramic Recipe

Claire Dancer says ceramics get overlooked because people think they are brittle, yet we use them all the time, from mugs and plates to light fittings and plug sockets. Making them traditionally means firing a powder in a furnace well above 1,000 °C for a long time. Her group works on new ways to make ceramics at much lower temperatures and with far less energy.

About the guest

Claire Dancer is a Reader at WMG, University of Warwick, in the UK, where she has led a ceramic processing group since 2013. She grew up near Cardiff, studied natural sciences and materials science at Cambridge, and did her PhD at Oxford on magnesium diboride, a superconductor. Postdocs on ceramic armour and on metamaterials followed. According to her Warwick profile, she also leads outreach and engagement for the UK Metamaterials Network.

Claire Dancer curated the Real Scientists Nano Twitter account (@RealSci_Nano) from December 5 to December 12 2022. Read all of Claire’s tweets from that week.

Key highlights in this episode

• 06:07 Ceramics are everywhere. From mugs and plug sockets to batteries, ceramics do jobs metals and polymers can’t. But 90% of the energy in a ceramic’s lifetime goes into making it.
• 12:08 Armour, bricks and knives. Soldiers’ body armour is ceramic, your house is built from ceramic bricks, and a zirconia knife stays sharp for years. Ceramics are extremely strong under compression.
• 19:43 Materials scientist from day one. Physics was the plan, until four weeks into a materials course at Cambridge. Then a superconductor PhD at Oxford, ceramic armour, metamaterials, and her own group at Warwick.
• 35:25 The best moment of her life. An industrial project to make one tube that was aluminium oxide at one end and silicon carbide at the other. It took 19 graded layers and months of broken samples before it finally came out of the press in one piece.
• 45:49 New recipes, lower temperatures. Flash sintering focuses the energy into the sample with an electric field, and cold sintering uses a little liquid and pressure at 100 to 300 °C.

Listen on

Why it matters

Claire explains that 90% of the energy in a ceramic’s lifetime goes into making it, and that without new processes the ceramics industry can’t hit its emissions targets. Switching old gas kilns to electricity and renewables helps, but on its own it doesn’t bring the energy use down enough. Lower temperatures also matter for devices. Solid-state batteries need dense ceramic layers, but sintering temperatures are so high that people glue ceramic particles together with polymer and lose the properties they wanted. Her group pushes temperatures below the melting points of metals and even polymers. The next challenge is scale: cold sintering needs pressure, and the goal is making pouch cells on a production line, not one coin cell at a time.

Terms explained

In the guest’s own words, with a link to the moment they explain it.

• Conventional ceramic processing: shape a powder into a pellet, then fire it in a furnace well above 1,000 °C (around 1,600 °C for aluminium oxide) so it densifies by solid-state diffusion. (Claire at 07:07)
• Flash sintering: connecting electrodes to the ceramic and passing an electric field through it while heating the furnace to a more modest temperature, so the energy goes straight into the sample. It often gives a flash of light. (Claire at 46:33)
• Cold sintering: adding a small amount of liquid and applying pressure at 100 to 300 °C, so a little material dissolves and the particles rearrange and fuse. (Claire at 48:52)

Related episodes

• Thermodynamics Doesn’t Care about You: Jose Ocaña-Pujol on metamaterials at high temperatures
• Cutting Through the Hype about 3D Printing: Candice Majewski on manufacturing
• Nature Inspired Additive Manufacturing: Hortense Le Ferrand on processing materials