POWDER-METALLURGY REPAIR OF TURBINE-COMPONENTS

An advanced powder metallurgy repair process called Liburdi Powder Met allurgy (LPM)(1) has been developed for the repair, overlay or joining of nickel and cobalt-based high-temperature alloys. This process invo lves mechanical cleaning, followed by the application and consolidatio n of a filler metal powder, which has substantially the same compositi on as the base metal, and produces joint with mechanical properties si milar to those of the parent material. While previously activated braz e 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 superio r microstructural features. The characteristics and typical applicatio ns of the LPM process for blade and vane repairs are highlighted and t he results of laboratory and engine tests are discussed.