LASER DRILLING OF AIR-FILM COOLING HOLES IN AIR AND WITH COAXIAL WATERJET ASSISTANCE

Air-film cooling holes were drilled into a turbine blade with 532-nm Nd:YVO4 nanosecond laser in air and coaxial waterjet assistance. The drilling quality of the sidewalls was investigated comparatively by means 3D confocal scanning microscope, electron microscopy, transmission X-ray diffraction energy-dispersive spectroscopy. Results have shown that maximum thickness processing-induced defects around air-film is up to 100 µm, while obtained asynchronous operation assistance indicate no spatter, oxide layer, recast layer or cracks. Compared air, minimum size heat-affected zone induced processing decreased down sub-micrometer scale. main phases are α-Al2O3, γ-Ni, β-NiAl, respectively. Asynchronous can help us achieve high position precision it will wide application.
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