Defining ceramics
Dr Ian Brown, a senior research scientist with Industrial Research Limited, explains how the term ‘ceramics’ now has a more expansive meaning. Traditional ceramics are clay-based, but high-performance or advanced ceramics are being developed from a far wider range of inorganic non-metal materials. Advanced ceramics have the properties of high strength, high hardness, high durability and high toughness.
Point of interest Will ceramic car engines replace the current metal-based ones?
Acknowledgements: Charlie Pfeifler Natalija Luketic NASA Rich Kaszeta
Transcript
DR IAN BROWN Ceramics as we knew them were very much aligned to cups, bricks and saucers materials, and a particular definition applied, which was that they were derived from inorganic clay-based materials and they were shaped and hardened by firing. But we are aware now that the definition of ceramics covers materials like high-performance or advanced ceramics, so it’s really any inorganic non-metal material that you can shape and harden by firing at some temperature, and this ends up with a hard, strong and durable body.
Traditional ceramics are made of materials from the earth, such as clay minerals that have been around and used by people way back to Roman and pre-history times and often blended or mixed with silica sands or feldspars, and these 2 or 3-component mixes were blended together to make pottery.
A clay-derived ceramic is typically constructed of a whole pile of linkages of oxygen and aluminium and silicon, maybe some calcium, maybe some magnesium. Advanced ceramic doesn't necessary have to have oxygen in its structure – it may have materials like nitrogen – and advanced or high-performance ceramics don't necessarily need to be earth-derived. They are actually fabricated by chemical synthesis roots, and they may actually be blended with traditional clays or silicas.
Advanced ceramics have particular advantages compared to traditional ceramics. I'm sure you are all familiar with traditional ceramics – they can be a bit fragile, a bit brittle – but some of these high-performance ceramics have extreme hardness and extreme strength. They have got little chemical and microstructural crack-stoppers in them, and these things absorb the energy in the crack, and we call these materials tough.
