International. An engineering research team from Canada's University of Alberta has identified a new material for coatings for high-temperature applications such as hydrogen combustion engines.
The newly developed alloy, AlCrTiVNi5, has superior thermomechanical properties. It includes high stability, low expansion, fracture tolerance, and a valuable combination of strength and ductility. This makes it capable of withstanding environments with high heat and high pressure.
The coating is made from a new alloy composed of metals such as aluminum and nickel. The new material is known as a complex concentrated alloy. It is ideal for coating surfaces that must withstand high temperatures. It includes, for example, gas turbines, power plants, vehicle and aircraft engines.
After identifying AlCrTiVNi5, the team subjected the new alloy to the same high-temperature tests used in existing commercially available alloys. All existing alloys failed after 24 hours or less in the hot, corrosive environment, but the new complex concentrated alloy stood up to the challenge.
Although the new alloy promises to withstand the heat of a hydrogen combustion engine with a high percentage, Liu, the project's supervisor, notes that more studies are needed before it can be widely adopted. Nonetheless, he remains optimistic about its potential.
Compared to commercially available alloys used as coatings in high-temperature applications, the new coating material holds up better than anything else, according to project supervisor Jing Liu, an assistant professor in the Department of Chemical and Materials Engineering. It could prove important for use in hydrogen engines.
Hydrogen is considered one of the cleanest energy sources. It only produces water when it is burned or used in a fuel cell. It plays an important role in Canada and Alberta's emissions reduction targets, for a variety of uses including transportation, home heating, and heavy industry.
One of the challenges of hydrogen adoption is the high temperature at which it burns, which ranges from 600 to 1500 degrees Celsius. These extreme temperatures mean that any mechanical components involved in hydrogen combustion must be able to withstand high temperatures and resist steam corrosion.
Hao Zhang, Jing Liu, Meifeng Li, Xuehai Tan and Haofei Sun.
Currently, most hydrogen combustion engines in commercial applications run on a combination of fuels: natural gas and hydrogen, or diesel and hydrogen. But as more industries work to adopt hydrogen as a primary fuel source, Liu sees the need to prepare for the ultra-high temperature conditions of an engine powered exclusively by hydrogen.
"If you want to use a 100 percent hydrogen combustion engine, the flame temperature is extremely high," says Liu, one of the researchers. "Until now, none of the existing metal coatings have been able to work in a 100 percent hydrogen combustion engine. " As we move toward a 100 percent hydrogen combustion engine, we want to know which alloys can withstand the conditions. None of the existing ones did, but we learn valuable insights from these failures."
