The formation of cracks in single crystal (SX) turbine blades is a common problem for aero-engines. To repair cracks, which are located under the tip-area, a new method is to clad with single-crystal-technology. This technology use multi-layer cladding to replace the single crystal material. To regenerate cracked material it is necessary to remove the crack affected material. The used notch geometries to remove the crackaffected area must be weldable and also permit the material solidification in the same oriented plane as the original microstructure. To solidify in the original structure a thermal gradient has to be introduced in order to guide the grain growth. This required gradient can be established by inductive heating. To reduce the thermal effected zone, a laser source is used. In addition, it is also an efficient process to fill the notch. Also the small local heat input and controlled material supply support the epitaxial growth. However, there are requirements to achieve a SX structure without cracks and pores. Current achievements and further challenges are presented in this paper.
Current laser cladding technologies have limited resolutions of about 50 μm. A new solution has been developed within the project ‘Nanomicro’ to improve the spatial resolution. The ‘micro hollow laser beam system’ and a deposition system for highly focused metal micropowders are innovative parts within a high-precision 3D micromanufacturing laser cladding platform. We demonstrate, here, a new hollow laser sintering concept that is aiming on more efficient laser cladding and manufacturing of highly precise and functional parts in the range of a few microns.
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