Germany. Researchers at the Fraunhofer Institute for Chemical Technology (ICT) have developed a coating technique that they plan to use to protect turbine engines and waste incinerator components against heat and oxidation.
A finishing layer of micro-scale hollow aluminum oxide spheres provides thermal insulation, in the laboratory scientists have already shown that it is more economical than conventional techniques.
According to the report, gases do not conduct heat, as solids do. Cellular or gaseous concrete takes advantage of this effect, which experts call "gas phase isolation." The heat barrier is obtained by the air enclosed in the cavities of the concrete. But gas-phase insulation has much greater potential than keeping homes warm. It can also be used to protect turbine engine components from waste incinerators and when subjected to intense heat. All that is needed is to transfer this effect to a layer that is only a few hundred micrometers thick.
In addition, the researchers confirmed that this development has been done in an especially economical way. They have designed a coating consisting of an outer finishing layer of the bonded aluminum oxide spheres. "These spheres are hollow and full of gas," explained Dr. Vladislav Kolarik, from ICT's Energy Systems department.
When the outer side of a part is exposed to temperatures of 1000°C, these gas-filled spheres reduce temperatures in the inner side parts below 600°C – as ICT scientists have shown in their laboratories. From gas and steam turbines used for power generation, to combustion chambers, waste incinerator generators and temperature sensors, and reactors in the chemical and petrochemical industries, all are subjected to temperatures of up to 1,000°C, there is a considerable demand for thermal protection.
