Researchers at University West in Sweden have started using nanoparticles in the heat-insulating surface layer that protects aircraft engines from heat. In tests, this increased the service life of the coating by 300%. The new layer could be used in both aircraft engines and gas turbines within two years.
To increase the service life of aircraft engines, a heat-insulating surface layer is sprayed on top of the metal components. This extra layer shields the engine from heat. The temperature can also be raised, which leads to increased efficiency, reduced emissions, and decreased fuel consumption.
The goal of the University West research group is to be able to control the structure of the surface layer in order to increase its service life and insulating capability. They have used different materials in their work. The base is a ceramic powder, but the researchers have also tested adding plastic to generate pores that make the material more elastic, said Dr. Nicholas Curry, who presented his doctoral thesis on the subject.
The ceramic layer is subjected to great stress when the enormous changes in temperature make the material alternately expand and contract; elasticity of the layer is therefore important. Over the last few years, the researchers have focused on further refining the microstructure.
The nanoparticles are so fine that direct spraying of the powder onto a surface is not possible; the team first mixes the powder with a liquid that is then sprayed is a process called suspension plasma spray application.
The ceramic powder mixture is sprayed onto a surface at a very high temperature—7,000 to 8,000 degrees C—using a plasma stream. The ceramic particles melt and strike the surface, where they form a protective layer that is approximately half a millimeter thick.
Dr. Curry and his colleagues have since tested the new layer thousands of times in thermal shock tests to simulate the temperature changes in an aircraft engine. The new coating layer lasts at least three times as long as a conventional layer while it has low heat-conduction abilities.
Research at University West is conducted in close collaboration with aircraft engine manufacturer GKN Aerospace (formerly Volvo Aero) and Siemens Industrial Turbomachinery, which makes gas turbines.