Composite metal foam (CMF). North Carolina State University
A new material, called Composite Metal Foam (CMF), could advance the automotive and nuclear power industries.
Interestingly, the material is both light and strong, capable of withstanding repeated heavy loads at scorching temperatures
The North Carolina State University researchers have designed this cutting-edge, strong material.
In extensive testing, CMF was found to maintain its integrity even when subjected to millions of stress cycles at up to 1,112 degrees Fahrenheit (600 degrees Celsius).
It could be used in anything from car engines and jet parts to specialized nuclear reactor technology (reactor fuel cladding).
“CMF has many attractive properties, which make it appealing for a wide range of applications,” said Afsaneh Rabiei, corresponding author and a mechanical and aerospace engineering professor, in the press release on October 7.
CMF is made of steel spheres
CMFs are created by embedding hollow spheres (made of metals like stainless steel or nickel) within a solid metallic matrix.
This unique composition makes CMF remarkably strong at absorbing crushing forces and provides superior insulation against high heat compared to conventional metals like steel.
In this new work, researchers used CMF made of steel spheres in a steel matrix to test the performance under extreme conditions. The design offers a high strength-to-weight ratio.
These samples were then subjected to repeated compression-compression loading at three different temperatures: room temperature 73.4 degrees Fahrenheit (23°C), 752°F (400°C), and blistering 1,112°F (600°C).
The CMF demonstrated exceptional fatigue resistance at 752°F (400°C).
The material endured over 1.3 million repeated stress cycles during testing, where the load alternated between 6 and 60 megapascals (MPa).
Even at the extreme temperature of 1,112°F (600°C), the material withstood a load cycle between 4.6 and 46 MPa for more than 1.2 million cycles without any sign of failure.
In both high-temperature tests, the researchers halted the tests due to time constraints, meaning the CMF’s true fatigue limit was even higher.
“Knowing that in a compression-compression fatigue setting, the fatigue life of solid stainless-steel decreases significantly as temperature increases from room temperature to 400°C and 600°C, these results were remarkable,” Rabiei said.
“Our findings indicate the fatigue life of the steel-steel CMF is not diminished and that this lightweight material performs tremendously well in the extreme environment of high temperature cyclic loading,” the author added.
The reliability of CMF under extreme conditions is crucial for applications where equipment failure could impact public health and safety.
The performance of metal foam surpasses that of solid stainless steel under high-temperature settings.
The initial impetus for this research was to develop a material for improved safety and efficiency in shipping hazardous materials.
The testing showcases the material’s potential in demanding applications where equipment is subjected to high stress and heat over a long operational lifespan.
The researchers plan to partner with industry to explore and develop the numerous potential applications for CMF.
The combination of lightness, strength, and thermal resistance makes CMF highly promising for diverse applications, from aircraft wings and vehicle armor to the safe storage and transportation of nuclear, hazardous, and other heat-sensitive materials.
The study findings have been published in the Journal of Materials Science.
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