Recently, Northwestern Polytechnical University (NPU) in China announced the successful development of a new type of ultra-high-temperature alloy material that can withstand temperatures of up to 2400 degrees Celsius. This material exhibits the same stability at both high and normal temperatures and possesses excellent oxidation resistance. This breakthrough is expected to play a crucial role in the research and development of China’s new generation of aviation engines.
Engines are one of the key factors in aerospace technology. Historically, China has lagged in this area, lacking a “big heart” to drive the development of various aircraft.
The alloy developed by NPU will accelerate the development of Chinese engines, directly impacting the research and development of China’s sixth-generation fighter jets. What are the specifics of this alloy material, and how did NPU develop it?
The Rigorous Requirements of Materials for Aviation Engines
The most critical part of an aviation engine is the high-pressure turbine. Current turbines can reach speeds of over 10,000 revolutions per minute, generating temperatures up to 1800 degrees Celsius. For China’s developing sixth-generation fighter jets, such engines still fall short.
Ideally, China’s sixth-generation fighter jet is expected to reach a flight speed of 20 Mach, 20 times the speed of sound, flying over 6800 meters per second. Using a turbofan engine means the high-pressure turbine would have to withstand intake temperatures exceeding 2100 degrees Celsius. Such high temperatures are beyond the capabilities of ordinary alloy materials.
High temperatures are just the first hurdle. As part of an aircraft, the engine must remain sturdy and unchanged under high temperatures and retain stability when returning to normal temperatures, a property known as room temperature toughness. For example, while ceramics can withstand high temperatures, they shatter easily at room temperature and thus are not suitable.
Additionally, the material must resist oxidation at high temperatures. Many metals react with oxygen in the air at high temperatures, forming a layer of oxides on the surface that continuously peels off, causing severe deformation of the material. An engine using such materials would be unreliable.
Meeting just one of these conditions would yield many suitable materials, but finding one that meets all these stringent requirements is challenging.
The ultra-high-temperature alloy material developed by NPU satisfies all these conditions. The primary component of this alloy is niobium alloy. Niobium (Nb) is a metal with a melting point of over 2400 degrees Celsius, inherently resistant to high temperatures. The alloy made from it combines high-temperature resistance, corrosion resistance, oxidation resistance, and toughness.
Processing Niobium Alloy
While the material is available, producing the corresponding parts requires processing. For the blades of a high-pressure turbine, specific dimensions and shapes must conform to standard airfoil curves, and the blades must have precise internal channels with no room for error.
This necessitates smelting the niobium alloy, which requires temperatures above 2000 degrees Celsius during research and testing. Finding a container that can withstand such high temperatures is challenging, and any contamination during the smelting process renders the materials unusable.
On Earth, these problems are difficult to solve, but what about in space?
In the space environment, all substances are weightless. For example, during smelting or experimental mixing, niobium alloy can be suspended in space and heated using microwaves or electromagnetism to reach its melting point. Researchers can then manipulate it freely.
China’s Tiangong Space Station has already established a “National Space Laboratory” with a “High-Temperature Materials Science Experiment Cabinet” and a “Containerless Materials Experiment Cabinet” specifically for materials science research, providing an excellent space research environment for developing various materials.
NPU has been researching this ultra-high-temperature alloy material since 2021. Through the Tianzhou-3, Tianzhou-4, and Tianzhou-5 cargo spacecraft, batches of experimental materials were sent to the space station for extensive testing of various alloy formulas, ultimately determining the optimal composition for niobium alloy.
In the future, to process special materials like niobium alloy, China may move “factories” to space. In a microgravity environment, efficiency will significantly increase, and reliability will be ensured.