Figure 1.  Nozzle with LPM® repair of cracks in airfoils and fillets - after 24,000 hours of service,  no return of cracking damage.

Blade Repairs

LPM® uses powder alloys of matching composition, where applicable, to provide high strength and fatigue resistance. Repair limits can now be extended to higher stressed areas which were not previously repairable. For the latest advanced engines, the LPM® process is being used to manufacture blade tips with superior oxidation and wear resistance.

Vane Repairs

Structural areas can now be repaired with LPM® alloys exceeding the vane material strength and without the distortion caused by welding. LPM® can also be used to build-up and restore thin airfoil and shroud seal surfaces that have eroded in service. Many vanes experience major cracking in the high stress fillet areas which are not effectively repaired using conventional weld repair. These same parts after repair with higher strength LPM® are providing reliable service, and out-performing conventional weld repairs. The process is approved by OEMs for both aeroderivative and heavy duty frame components.
 
New Component Manufacture

Engine manufacturers are currently using the LPM® process to join high strength materials and close cavities in new castings for turbine blades and vanes. Special LPM® compounds are also being used to apply an oxidation resistant, abrasive tip to the new generation of high pressure turbine blades.

Superior Strength and Metallurgical Structure

The unique LPM® powder metallurgy process produces a dense deposit with little or no porosity and a metallurgically inter-diffused interface with the substrate alloy. The microstructure is typical of fine grained powder metallurgy alloys and exhibits excellent strength and fatigue properties.

Liburdi Powder Metallurgy (LPM ® )

Liburdi Powder Metallurgy, LPM®, is a patented high strength process used in the manufacture and repair of blades, vanes and other superalloy turbine components. LPM® offers superior strength and performance compared to conventional diffusion braze and weld repair methods. The LPM® powder metallurgy compositions can be formulated from a wide range of alloys depending upon the properties required, including IN738, Mar M247, Rene80, X40, MCrAlY’s and Chrome Carbide. The LPM® alloys can be manufactured and applied as either flexible tapes of varying thickness or as a moldable putty for cavities or fillets.

LPM® employs advanced metallurgy to achieve high strength repair joints, in conjunction with reliable mechanical preparation of the surfaces. Damaged areas are first removed by grinding similar to preparation for welding. Then new LPM® material in putty or tape form is applied to fill the area; the part is then processed through specialized vacuum heat treatments and machined or blended to the final dimensions.

RB211 IPT Nozzle Guide Vane with LPM® repair material applied to oxidized metal damage to shrouds and to the leading edge to restore original wall thickness - next step is to machine to final dimensions.