US Patent 7653996 - Nanoparticles for crack repair in gas turbine

http://www.freepatentsonline.com/7653996.html

Turbine engines undergo high thermal and mechanical stress during operation which can produce cracks and limit their life expectancy. This patent from Siemens AG teaches the benefits of using nanoparticles to improve life expectancy such as the low melting point of nanoparticles and penetration into smaller cracks. Claim 1 reads:

1. A method of repairing a crack in a gas turbine component having a base material characterized by an annealing temperature, comprising:

forming a suspension comprising a carrier liquid and nanoparticles which are not soluble in the carrier liquid;

applying the suspension to penetrate into the crack to be repaired;

heating the suspension at a first temperature to evaporate carrier liquid with the nanoparticles being compacted; and

further heating the component to a more elevated temperature below the annealing temperature, wherein the elevated temperature is approximately 50 K above the first temperature and below the melting temperature of the base material, to melt the nanoparticles and form a bond between the nanoparticles and the base material, the further heating at the more elevated temperature having a duration of less than 30 minutes.