Pulsed Laser Ablation of Reparable Erosion-Resistant Coatings for Aerospace

摘要

The lifetime of titanium-alloy aerospace parts can be greatly enhanced by the application of erosion resistant coating (ERC). After many hours in service, the coating will inevitably begin to deteriorate. In order to re-coat and repair the parts, the coating should be removed. We present here a first attempt to strip TiN-based ERCs with a Ti:sapphire femtosecond pulsed laser emitting at 800 nm. Following initial testing, we optimized four critical laser parameters: power, beam diameter, stage speed and step distance. The optimal etch was obtained with a power of 300 mW, a 0.16 mm beam diameter, a stage velocity of 0.65 mm/s, and a step distance of 35 μm. This process exhibits high surface quality, but a rather slow etch rate. Nonetheless, EDX measurements confirmed full removal of the coating. To increase selectivity, plume emission spectroscopy has also been investigated in order to help control, in real time, the material removal in regions where the coating thickness varies.