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Materials Science

Improving Performance and Turbine Longevity

Materials science applications may reduce the cost of deploying new hydropower or extend the lifespan of existing hydropower projects. These state-of-the-art techniques can reduce the number and duration of outages and replace dated techniques that risk damage to ancillary systems.

Cold Spray

PNNL is researching alternative ways to repair cavitation damage on hydropower turbines in an effort to reduce outages and keep service and maintenance costs down. Cold spray is one alternative method which works by shooting metal particles at very high speeds into the damaged area. The impact energy created by these high speeds produces a solid-state weld between the particle and the turbine surface. With this method, melting and material degradation common in current welding repair techniques does not occur and hydropower turbine blades are left in their original shape. Even better, cold spray repair is capable of depositing materials with hardness and wear resistance that match or exceed that of the turbine base metal—meaning cold spray repairs should produce superior performance in repaired turbines.

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Friction Stir Welding

Friction Stir Welding

Solid state joining processes like the friction stir welding processes developed at PNNL enable welding of many materials otherwise considered unweldable. These processes allow not only the joining of metals with very different melting temperatures, but also chemically different materials such as polymers to metals or composites. Friction stir processes may be used for a number of hydropower applications. Sensors could be embedded into turbines to monitor those very difficult to observe environments. Hydropower components could be given new life or even be made of cheaper base materials with harder materials welded on in damaged or high wear areas.

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Water Power Research