New ceramic composites that could potentially greatly improve the fuel efficiency of jet engines and reduce pollution are now being tested thanks to a new testing facility, the first of its kind, created by the Department of Energy (DOE)’s Lawrence Berkeley National Laboratory (Berkeley Lab). Because of how light they are, and their ability to withstand extremely high temperatures, they could be a great boon to the development of hypersonic jets and next-generation gas turbine engines. It had been difficult to do a truly in-depth analysis of these space-age materials until now, but thanks to the new lab, CT-scanning of different ceramic composites while “under controlled loads at ultrahigh temperatures and in real-time” is now possible.
Ceramics have long been a valuable construction material. Their ability to withstand water, chemicals, oxidation, and extreme heat, while remaining essentially unchanged, makes them a very useful material. They are also generally much lighter than their main rival material, metals, potentially leading to great increases in efficiency in many moving technologies. They have remained somewhat underused because of their brittleness, though. And while the ceramic fiber-reinforced advanced ceramics of today are much stronger than regular ceramics, their structural complexity has limited their use in engines, and elsewhere, because of questions that remain about their safety. The new testing laboratory should go a long way to improve the material’s safety and performance.
“Working at Berkeley Lab’s Advanced Light Source (ALS), a premier source of X-ray and ultraviolet light beams, the scientists created a mechanical testing rig for performing X-ray computed microtomography that reveals the growth of microcrack damage under loads at temperatures up to 1,750 degrees Celsius,” Berkeley Lab reports. “This allows engineers to compute a ceramic composite material’s risk of structural or mechanical failure under extreme operating conditions, which in turn should enable the material’s performance and safety to be improved.”
“Like bone and shells, ceramic composites achieve robustness through complexity, with their hierarchical, hybrid microstructures impeding the growth of local damage and preventing the large fatal cracks that are characteristic of brittle materials,” Ritchie says. “However, complexity in composition brings complexity in safe use. For ceramic composites in ultrahigh temperature applications, especially where corrosive species in the environment must be kept out of the material, relatively small cracks, on the order of a single micron, can be unacceptable.
“The capacity for validating virtual testing models through direct, real-time, non-invasive experimental observations should greatly advance our understanding and help promote the technological innovation of ceramic composites.”
Source: DOE/Lawrence Berkeley National Laboratory
Image Credit: DOE/Lawrence Berkeley National Laboratory
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