– Carbon powder transformed into graphite in a microwave oven – Design Merchandise & Functions
January 08, 2021
Researchers at the University of Wyoming have shown that using copper foil, glass containers, and a conventional household microwave oven, powdered carbon powder can be converted to higher quality nano-graphite.
The discovery is another step forward in efforts to find alternative uses for Wyoming’s Powder River Basin coal at a time when the demand for coal for power generation is declining due to climate change concerns.
In an article published in the journal Nano-Structures & Nano-Objects, the UW researchers report that they created an environment in a microwave oven in which raw coal powder can be successfully converted into nano-graphite, which is used as a lubricant, and into Articles of fire extinguishers for lithium-ion batteries. This “one-step, metal-assisted microwave treatment” approach is a new approach that could be a simple and relatively inexpensive technology for converting coal.
“This method offers a new way to convert abundant carbon sources into high quality materials with ecological and economic benefits,” wrote the research team, led by Associate Professor TeYu Chien at the UW Institute of Physics and Astronomy.
While previous research has shown that microwaves can be used to reduce the moisture content of coal and remove sulfur and other minerals, most of these processes require specific chemical pretreatment of the coal. In their experiment, the UW researchers simply grind raw Powder River Basin coal into powder.
This powder was then placed on copper foil and sealed in glass containers with a gas mixture of argon and hydrogen before it was placed in a microwave oven. A conventional microwave oven was chosen for convenience and because it provided the desired levels of radiation.
“By cutting the copper foil into a fork shape, the sparks were induced by the microwave radiation and generated an extremely high temperature of more than 1,800 degrees Fahrenheit within a few seconds,” says Masi, lead author of the paper. “That’s why you shouldn’t put a metal fork in a microwave oven.”
The sparks caused by the microwaves created the high temperatures required to convert the carbon powder to polycrystalline graphite, with the copper foil and hydrogen gas also contributing to the process.
While the experiment included microwave durations ranging from 3 to 45 minutes, an optimal duration of 15 minutes was found.
The researchers say that this new method of carbon conversion could be refined and performed on a larger scale to obtain both higher quality and higher amounts of nano-graphite materials.
“Finite graphite reserves and environmental concerns with graphite extraction processes make this method of converting carbon to graphite a great alternative source for graphite production,” the scientists wrote.