New Carbide Ceramics Aid Supersonic Air Travel
Posted by Cathie Montanez on September 5, 2019 5:45 AM EDT
A civilian supersonic jet, which can travel across the globe in a matter of hours, would drastically cut global travel time.
In general, we call aircraft with Mach number less than 1 subsonic aircraft, aircraft with Mach number greater than 1.2 supersonic aircraft, and aircraft with Mach number greater than 5 ultra-sonic aircraft. Flying at Mach 5 will create temperatures of up to 2,000 to 3,000 degrees Celsius on the surface of the aircraft, where the coating material can be easily broken down. The development of supersonic aircraft must solve the problem of accumulated heat on the surface of aircraft. A team of Chinese and British scientists has discovered a new carbide ceramic the coating that could speed up supersonic aircraft.
Carbides are currently one of the most heat-resistant materials, expressed in general formula MxCy. According to the different properties of M, carbides are roughly divided into metal carbides and metal-like carbides. Carbide ceramics is one of the most commonly used high-temperature resistant structure ceramics, common high-temperature resistant ceramics are silicon carbide, zirconium carbide, boron carbide, tungsten carbide and so on, all of these ceramic materials generally have a high melting point, high hardness and chemical stability.
Any material exposed to a high enough temperature will lose its molecular chains and become ablated if it is washed with high-speed particles. Zirconium carbide, for example, a traditional ceramic coating material, is effective in heat resistance but is easily degraded. Zirconium diboride is the new hope for high-temperature coating materials for aircraft because it can resist oxidation at high temperatures and is low in density and cost. But the fatal drawback is that the boron in zirconium diboride further facilitates ablation when boron atoms oxidize.
The newly the developed carbide coating material can endow the coating with super strong and oxidation-resistant structure and can resist the ablation and oxidation in high temperature environment.
The new coating is a ternary alloy mixture made of zirconium, titanium, carbon, and boron. It is deposited into a carbon composite by a process called reactive melt penetration. Although it has similar properties to other carbide ceramics, its relatively low boron concentration makes it less likely to be melted. The results show that the carbide coating has better ablation resistance than the existing candidate UHTC (such as zirconium carbide and diboride) at 2000 ~ 3000℃.
At present, civil aviation aircraft usually fly at subsonic speed. A civilian supersonic jet, which can travel across the globe in a matter of hours, would drastically cut global travel time. The coating is favored by Boeing, which plans to fly supersonic passenger planes within a decade. Although supersonic airliners are still a long way from our lives, the discovery of the coating material could help make supersonic airliners commercially viable.
Stanford Advanced Materials supplies high-quality carbides products to meet our customers' R&D and production needs. Please visit https://www.samaterials.com/ for more information.