Composite materials made of technical ceramics are becoming a major ingredient in jet engine and power-generation technology components.
Think of a material that is as tough as a metal, not as brittle as a ceramic and that can survive a temperature of 1316 degrees Celsius. The answer is silicon carbide – not the compound on its own, but embedded as a fibre that is almost six times thinner than a human hair in a ceramic matrix.
This combination of silicon carbide fibres within matrices – ceramic matrix composites – is one of group of super Technical ceramics that was created by NASA’s Glenn Research Center. The resulting material can be used to make components for gas turbines in power-generation plants as well as engines in the aerospace sector.
This silicon carbide/silicon carbide matrix mix is a super technical ceramic that has all of the strength advantages of metals, with a higher temperature tolerance and chemical resistance, but only two-thirds of the weight.
Whether in power-generation turbines or jet engines, these ceramics can potentially create greater thermal efficiency in any process and so generate more power but save on fuel at the same time.
It also means that any components made from these materials are not only lighter but will require far less cooling by air, water or other means.
Engineers at General Electric are hoping to mass-produce these ceramics. The company’s engineers believe that when used as components in jet engines they will be able to increase the engine’s thrust by at least 25% and even decrease fuel consumption by 10%. But this is not expected to happen until 2020.
The downside here is the same for all technical ceramics. They are not always easy to mass-produce, and so it will take some years for companies like General Electric to build up an efficient supply chain that is equivalent to its metals supplies.
For this reason, super ceramic components have been really limited in application to the space sector and in fighter jets for the military.
Work on a commercial jet application started in 2015, when ceramic matrix composites were tested in General Electric’s GEnx engine. This engine is used in many versions of the Boeing Dreamliner.
The company also wants to use this material for fabricating fans and even compressor blades on its GE9x engine, which is currently being developed. Once in production, this will be the world’s largest ever jet engine in a commercial aircraft. It will have a fan with a 3.4 metre diameter.
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