Experiments of drilling micro-holes on superalloy with thermal barrier coatings by using femtosecond laser

A femtosecond laser was used to process micro-holes on the nickel-based superalloy with thermal barrier coatings. Scanning electron microscope (SEM) was used to observe the morphology of micro-holes inlet, outlet and the side wall. The changes of morphology with laser focusing position and laser power were analyzed. The results showed that the micro-holes processed by femtosecond laser required a certain amount of focus position to optimize the processing quality. The entrance was not round sometimes and the micro-holes outlet was irregular with high power laser machining. A further repair of micro-hole by using low power femtosecond laser was presented. Low laser power modification can improve the quality of micro-holes.