Nanosecond‐Laser Postprocessing of Millisecond‐ Laser‐Machined Zirconia (Y‐TZP) Surfaces

Abstract

Millisecond‐pulsed Nd:YAG laser systems can be used for high‐speed cutting of ceramics, due to the high average power available. However, due to the relatively long pulse duration (0.3–5 ms), millisecond laser‐machining is predominantly a thermal, melt‐eject process. The quality of the finished surface is limited by a redeposited melt and a heat‐affected zone, in particular surface cracking. Shorter pulse duration lasers can provide a better surface finish but with a significantly longer processing time. This paper presents a method of improving the finish of millisecond‐machined yttria‐stabilized tetragonal zirconia polycrystal surfaces by postprocessing with a nanosecond‐pulsed laser. Nanosecond machining was carried out directly onto the as‐cut surface produced after millisecond processing, yielding a dramatic improvement of the surface finish in a relatively short time.