Nanosecond-laser postprocessing of millisecond-laser-machined zirconia (Y-TZP) surfaces

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. © 2008 American Ceramic Society.