New brazing alloys to improve thermal barrier in jet engines
The aerospace industry is looking for new options to run gas turbine engines longer and hotter in order to save operating costs by reducing the use of compressor air.
Ceramics component manufacturers have been working on developing new alloys that can be combined with the parent metals in the engine to enable them to run hotter, according to an article by Morgan Technical Ceramics, which produces braze alloy compositions for use in the compressors.
Morgan manufactures some 15 braze alloy compositions, including Nioro, a gold/nickel alloy for vacuum brazing.
The ceramic industry is developing various grades of braze alloys to bind ceramics with metal in military aircraft and commercial aerospace engine components.
The air from the compressor cools the turbine vanes and blades and the amount of air needed to cool them depends on the temperature of the turbine as well as that of materials.
Excessive heat damages the vanes, which are repaired using pre-sintered preforms (PSPs).
Mixing of braze alloys in the original metals and the PSP will improve the endurance of the vanes, thus reducing the maintenance costs.
If the turbine materials can withstand higher temperature, they will require lesser air for cooling, making more air available for propulsion.
Nickel braze alloys are used in compressor and turbine section brazing, and in its foil form, it can be used for brazing honeycomb and metal seal strips. They demonstrate effective corrosion resistance.
Another area of growing interest in the industry is active metal brazing, which allows metal to be bonded directly to ceramic without metallisation.
Image: Common locations for use of alloys in turbofan engine. Photo: courtesy of the Morgan Crucible Company.