(source: uva official website)
Compared with gasoline, natural gas burns cleaner and more efficiently, produces about 25% less carbon dioxide, and has lower refining and processing costs. Therefore, natural gas powered vehicles are increasingly concerned. However, due to the high combustion temperature of natural gas, the requirements for metal engine parts are much higher.
According to foreign media reports, researchers at the University of Virginia developed a new high temperature resistant low-cost alloy by combining nickel powder and graphene sheet, and applied for a patent. This new metal matrix composite can maintain integrity at 1000 ℃, or it will become a good choice for natural gas engine materials.
These lightweight materials are known as graphene superalloys. Because of the use of light graphene material, it is lighter than other nickel superalloys, but more durable than other metal mixtures. Chris Li, a professor at the school of mechanical and aerospace engineering who led the research, said: "this material is very light, and has a perfect combination of strength and toughness, which could become an ideal material for key components of natural gas engines such as fuel nozzles."
When designing materials, researchers draw inspiration from nature, such as mother of pearl shells. "They have layers of structure." Mother of pearl is composed of hexagonal aragonite sheets, and its strength and toughness are very rare in engineering materials. In the manufacture of most composite materials, the combination of the two alloys will lead to the loss of ductility or toughness of most composite materials. However, with the structure similar to aragonite, the strength of graphene and nickel composite can be increased by 73%, and the tensile strength can only be reduced by 28%. The composite can even maintain high hardness at 1000 ℃.
Replacing battery and engine materials with graphene reinforced materials will help to reduce energy consumption. The challenge is that graphene can cost hundreds of dollars per gram. "When applied to vehicles, cost needs to be considered," said Zhang, a leading researcher. Cost always comes first. If we can't reduce the cost of graphene, we can't use graphene in a large number of cars. "
Researchers predict that in the next five years or so, natural gas engines may be widely used, especially for commercial trucks. Trucking companies are looking for ways to reduce fuel costs and carbon emissions. Currently, the U.S. Department of energy and transportation is supporting innovative materials research to adapt to alternative fuels and reduce costs and greenhouse gas emissions. Graphene can be used to improve common technology on a smaller scale and at a lower cost. For example, it can be used to make flexible screens, even flexible batteries for mobile phones, or 3D printing.
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