Ian Sheppard/LONDON
GE Aircraft Engines is pioneering use of a laser surface treatment technology to increase significantly the crack resistance, fatigue life and impact strength of turbine engine blades.
The technique, known as laser peening, introduces compressive stresses in metals to four times the depth achieved with traditional shot peening, the current de facto standard for surface hardening of engine components.
GE confirms that it has a customer which is putting funding into the technology but declines to give further details. The company is reported to be using the process to treat the blades of its F101 engines for the US Air Force's Rockwell B-1B bomber fleet, and is preparing to use it on the F110-100B engine upgrade for the Lockheed Martin F-16C/D.
Traditional shot peening involves blasting beads at the component at very high speed, helping to introduce compressive stresses and therefore prevent crack propagation to a depth of around 10mm. It may, however, damage the aerodynamic effectiveness of a surface. By contrast, a laser does not affect the finish and has been found to reach a depth of 40mm.
Meanwhile, Lawrence Livermore National Laboratories, based at the University of California, and Curtis Wright's Metal Improvement Company (MIC), based in New Jersey, are working together to commercialise the technology as "Lasershot" peening.
The companies are developing a $1 million next-generation pulsed solid-state laser, which MIC says has become available thanks to advances in laser cooling. It will be up to 50 times more powerful and have a frequency 20 times faster than anything in commercial use today, says MIC, which expects to spend around two years experimenting on components such as gas turbine blades and shafts.
Source: Flight International