A new study has found that a lightweight type of metal foam can efficiently block X-ray, neutron radiation and gamma rays. The said research was also able to discover that these foams can take in the energy of collisions, which exhibit significantly high forces. According to the authors, the findings of their study may pave the way for improved research on nuclear safety, space studies and healthcare applications.
The researchers from the North Carolina State University conducted the study by performing a series of tests that identify the performance of several materials against gamma rays. Various objects emit gamma rays with different levels of energies such as the high-energy produced by cesium and cobalt and the low-energy produced by americium and barium.
The results of the study, published in the journal Radiation Physics and Chemistry, show that a metal foam called "high-Z steel-steel" exhibited the most effective shielding performance against the three types of radiation. This foam is composed primarily of stainless steel with subtle amounts of tungsten. The entire composition of the high-Z foam was altered so that the effect of tungsten on the density of the foam would not deviate from the metal foam made of pure stainless steel.
"However, we are working to modify the composition of the metal foam to be even more effective than lead at blocking X-rays—and our early results are promising," said Afsaneh Rabiei, corresponding author and professor of mechanical and aerospace engineering at North Carolina State University. The modified foams are potentially less hazardous or toxic; hence, it is more conducive for recycling and manufacturing, she added.
The researchers also found that the high-Z foam and bulk objects have similar blocking capabilities against high-energy gamma rays. However, when low-energy gamma rays were emitted, the high-Z foam manifested far better shielding power than bulk objects, including bulk steel. Neutron radiation was also blocked by the high-Z foam better than any other objects. Although lead still tops the list for blocking the most amounts of X-ray, the high-Z foam was also nearly effective.
Rabiei initially created the lightweight metal foam for transportation and military purposes; however, she also wanted to know if the said foam could also be beneficial for nuclear and space research purposes. With the results of this new study, Rabiei is positive that composite lightweight metal foam may help to move nuclear wastes more safely and provide more effective shielding equipment for diagnostic imaging studies such as CT scans.
