New ceramic coating will make flying at hypersonic speeds one step closer to reality
The idea of flying at hypersonic speeds has been in the scientific and technological world for a long time. But creating an aircraft that can travel at Mach 5 (6,125 kilometers per hour) or faster requires new materials, some of which are still under development. Such materials can be safely attributed to the protective coating of devices, a material that, without destruction and degradation, must withstand prolonged heating to a temperature of 3 thousand degrees Celsius, arising from friction against air.
And even if the high temperature does not melt or deform the edges of the planes, the nose cone, turbine blades and other structural elements of the hypersonic aircraft, this will cause the material from which the elements are made to become thinner and brittle, prone to pitting due to its intense oxidation during high temperature.
A group of researchers from the University of Manchester, UK, and Central Southern University, China, have long been working on the search for new types of high-temperature ceramics that are not susceptible to oxidation at high temperatures, have high strength and some elasticity. Long-term searches for such ceramics have yielded a result – a new type of carbide coating, which, according to the results of the tests carried out, is 12 times superior in all main parameters to all types of known high-temperature ceramics, such as zirconium carbide (ZrC).
Samples of the new ceramics were made at the Powder Metallurgy Institute of Central South University, and further processing and testing of these samples were carried out at the laboratories of the University of Manchester. Additional processing was carried out using the Reactive Melt Infiltration (RMI) installation, which bombards material samples with a stream of ions of zirconium, boron, titanium and other elements heated to a high temperature. Typically, exposure to high temperatures “expels” from the composition of ceramics those elements that give it high protective properties, which creates the prerequisites for its degradation. The processing of the ceramics on the RMI installation made it possible to “saturate” it with additional elements, which made it somewhat heavier and more resistant to high temperatures.
“The high-temperature ceramics we have found do not yet reach the ideal, they still cannot withstand a long stay in extreme conditions and are expensive to manufacture by themselves. However, this is all a demonstration of the potential of a new type of ceramics in terms of reduced evaporation and improved resistance to oxidation at high temperatures, “says Ping Xiao, professor of materials science at the University of Manchester.” In addition, we have shown that implementation in The ceramic composition of a carbon fiber framework is an effective way to improve a material’s resistance to thermal damage. “S
ource: http://dailytechinfo.org