Engineers create super alloy for high-temperature hydrogen engines

Engineering researcher Meifeng Li is part of a U of A team that identified a new super alloy composed of aluminum, nickel and other metals that shows potential for high-temperature coatings. Credit: University of Alberta

An engineering research team at the University of Alberta has discovered a new material that could revolutionize coatings for high-temperature applications, particularly in hydrogen combustion engines.

This innovative coating is made from a new super alloy composed of metals such as aluminum and nickel.

Known as a complex concentrated alloy, this new material is ideal for protecting surfaces that must endure extremely high temperatures, such as those found in gas turbines, power stations, and vehicle and airplane engines.

The newly developed alloy, called AlCrTiVNi5, boasts superior thermomechanical properties. These properties include high stability, low expansion, fracture tolerance, and a valuable combination of strength and ductility.

This means it can withstand high-heat and high-pressure environments better than current materials.

The study detailing this new alloy, titled “A novel entropy-stabilized oxide coating thermally grown from a valve metal-based complex concentrated alloy,” was published in the journal Materials Today.

When compared with existing commercially available alloys used as coatings in high-temperature applications, the new material outperforms them all, according to Jing Liu, the project supervisor and assistant professor in the Department of Chemical and Materials Engineering.

This new coating material could be particularly important for hydrogen engines.

Hydrogen is considered one of the cleanest sources of energy because it only produces water when burned or used in a fuel cell.

It plays a significant role in Canada and Alberta’s emissions reduction goals, with applications ranging from transportation and home heating to heavy industry.

However, one of the challenges of using hydrogen as a fuel is the high temperature at which it burns, ranging from 600°C to 1500°C. These extreme temperatures mean that any mechanical components involved in hydrogen combustion must be able to withstand high heat and resist corrosion from steam.

“If you want to use a 100% hydrogen fuel combustion engine, the flame temperature is extremely high,” says Liu. “Until now, none of the existing metallic coatings have been able to work in a 100% hydrogen combustion engine.”

Currently, most hydrogen combustion engines in commercial applications run on a mix of fuels, such as natural gas and hydrogen or diesel and hydrogen. However, as industries move toward adopting hydrogen as a primary fuel source, Liu sees a need to prepare for the ultra-high temperature conditions of a fully hydrogen-fueled engine.

“As we move toward a 100% 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,” she says.

The research team identified the strengths and weaknesses of each existing commercially available alloy. They then used theoretical simulations to identify potential new combinations that might offer the strength and durability needed.

Working with colleagues like Hao Zhang from the Faculty of Engineering, the team employed computer modeling to understand the properties of each potential new alloy.

This research could significantly impact the future of hydrogen engines and high-temperature applications. The new super alloy, AlCrTiVNi5, provides a promising solution to the challenges posed by hydrogen combustion, potentially making hydrogen a more viable and widely used clean energy source.

Source: University of Alberta.