Black cement is a solid, lightweight cement that can hold heat and pressure for years, says new research from the University of California, Berkeley.
A team led by Michael A. H. Schaffer of UC Berkeley’s Department of Materials Science and Engineering, has discovered that this type of cement is stable for years in a furnace with no oxygen.
“When you use a black concrete floor to hold a flame, you don’t have any other choice,” says Schaffer.
“You have to use it.
You cannot make a good product out of this stuff.”
It turns out that even when the material is heated to temperatures above 1,000°C, the cement retains heat and can remain stable even at temperatures that are hundreds of degrees above absolute zero.
“That’s very unusual,” says David A. Osterman, a materials scientist at Cornell University in Ithaca, New York, who wasn’t involved in the research.
“It’s a bit of a paradox.
If you’re using black cement to keep heat in the furnace, you’re going to have to keep a furnace running for a long time.”
The research, which appears online this week in the journal Science Advances, used a type of furnace known as a carbon-fiber-carbon (CFCC) heat exchanger.
These heat exchangers are used to remove heat from carbon-based materials, like concrete.
Carbon-fibre-carbon heat exchangs are widely used in buildings and other structures, and are also commonly used to heat water.
They also produce steam, and this heat is converted to electricity that can be used to cool cooling systems.
The carbon-carbon heater in the UC Berkeley research was designed to remove carbon dioxide, and to work well in a low-oxygen furnace.
But in a high-oxygene furnace, the carbon-fatigue-resistant CFCC heater would be unable to operate.
In other words, the researchers had to design a heat exchange that could handle the high temperatures required to operate the CFCC heat exchang.
“I have to admit, it was a bit daunting,” says Ostermans team leader Paul A. Schaeffer, a chemical engineer at the University in Washington.
“But it was really satisfying to get to the end of the design and make it work.”
The researchers measured the thermal performance of the carbon fiber-carbon-futuristic heat exchanging device in a carbon furnace that is cooled to about 3,000 °C, which is roughly half the temperature of a normal carbon-fueled furnace.
The team found that even after cooling to temperatures below 1,200 °C and using the carbon fibre-carbon furnace for about 10 days, the CFCFHC heater remained stable.
The temperature of the furnace itself was also stable at these temperatures, the team found.
“We’re not doing any real testing yet,” says Hillett.
“Our goal was to figure out what happens in the future.
The goal was always to have a thermal solution that could be scaled up to work in a normal furnace.”
The team then applied a heat-treatment system to the CFFC heater.
The researchers found that the temperature at which the heat exchilters were working was about 50 °C lower than when they were cooled to a higher temperature, and the temperature in the boiler was about 30 °C colder than when the heat-exchanger was cooling to a lower temperature.
In the end, the heat treatment system reduced the temperature by about 30%.
This allowed the heat to flow through the carbon furnace, and also reduced the CO 2 emissions that would normally occur when the furnace was operating at a low temperature.
The cooling process was similar to how it would work in other carbon furnaces, says Schaeff.
The heat-temperature reduction was significant, and not simply because the CFHC heat exchillators would have to be cooled to operate in a CFCC furnace.
“The effect is very dramatic,” says the UC professor.
“If you look at the carbon fibres, it’s quite significant.”
“What it says is, it can be made from the same material, but the temperature difference is quite large,” says Mark A. Dallam, a professor of chemistry at the Ohio State University in Columbus, Ohio.
“These kinds of structures are the basis of all of our plastics, all of the glass and all of these materials that we use.”
This research builds on the work of other researchers who have used carbon-cobalt and carbon-steel materials in high-temperatures furnaces to increase the efficiency of a heat source.
The new research builds off work by researchers at MIT and Stanford, and it is the first to show that a CFHC heater can be cooled using carbon fibre and carbon steel, says Dallams co-author Jason R. Laughlin.
“This is a new way to make a heat transfer system,” he says.