Laser repeat drilling of alumina ceramics in static water

The drilling of ceramic pores with a YAG laser beam raises some problems such as a big taper angle, accumulation of slag, and a recast layer. Three sets of experiments are conducted to verify that repeat drilling in static water can effectively reduce these problems by drilling once in air, repeat drilling in air, and repeat drilling in water. A mist-blowing method is adopted to blow over the water mist caused by laser heating. The effect of water on the alumina ceramics pores was studied under different laser electric currents and processing environments. The results show that the taper angle of repeat drilling is obviously reduced from 4 to 2.5A degrees, whether in the air or in static water. The slag, recast layer, and microcracking of the pore walls are also remarkably reduced under the condition of static water without a visible ablation phenomenon. The roundness of the pore is obviously improved from 0.9 to 0.98 with the mist-blowing method. The pore quality can be dramatically improved by using the method of repeat drilling in water with electric current of 160 A.