Turbine blades repaired with a coating process developed by Japan's Ishikawajima-Harima Heavy Industries' (IHI) have been cleared to enter service in February 2007. The MSCoating process improves resistance to abrasion, oxidation and erosion.
MSCoating uses an energy discharge to transfer a coating material, either sintered metal or ceramic powder, through a dielectric fluid on to the surface to be coated. The coatings can be up to 0.7mm (0.027in) thick.
The process has been tested on IHI-produced low-pressure turbine blades for the General Electric CF34 engine. After four months of operation the repaired blade showed no signs of wear. "We are preparing for mass production now. The plan is to start in October [for a 2007 entry into service]," says IHI's aeroengines and space operations division.
The distance from the coating material, which is in the form of a block, to the target surface is about 50 microns. The electric discharges are generated about 10,000 times a second. These discharges melt the coating block's surface and the target surface, enabling the coating material to be transferred and mixed with the molten target surface. With repeated discharges, the company claims a thick cladding can be produced.
Source: Flight International
