POWDER-METALLURGY REPAIR OF TURBINE-COMPONENTS

An advanced powder metallurgy repair process called Liburdi Powder Metallurgy (LPM)(1) has been developed for the repair, overlay or joining of nickel and cobalt-based high-temperature alloys. This process involves mechanical cleaning, followed by the application and consolidation of a filler metal powder, which has substantially the same composition as the base metal, and produces joint with mechanical properties similar to those of the parent material. While previously activated braze or ''wide-gap'' repair processes have been limited to clearances of approximately 1 mm, the LPM technique has the ability to bridge larger gaps of over 5 mm. In addition, the LPM joints contain significantly lower concentrations of melting point depressants such as silicon and boron than conventional wide-gap repair techniques and exhibit superior microstructural features. The characteristics and typical applications of the LPM process for blade and vane repairs are highlighted and the results of laboratory and engine tests are discussed.