Study On Laser Cutting Quality Of Zirconia Ceramic Sheet

Low thermal conductivity, low coefficient of friction, excellent corrosion and wear resistance, high fracture toughness, and good thermal shock resistance make zirconia suitable for use in automobile and biomedicine field. The micro adhering slag, recast layer and striations on the kerf surface are the problems during laser cutting. At present, some achievements in laser cutting zirconia have already made. However, the conclusions are all focusing on optimization of parameters. This thesis carries on laser cutting experiments on zirconia, which thickness are 0.8mm,1.0mm,1.5mm and 3mm, and also explains the relationship between vapor-melt ratio, thickness, melt particles and cutting quality.Melt and vapor are the two basic forms of material removal during pulsed laser cutting zirconia ceramic. A laser precision cutting method based on vapor-melt ratios controlled was used, systematically study the fluence of vapor-melt ratio and thickness on the cutting quality, that is the effects on kerf quality, kerf surface striation formation and roughness. Through observing on samples of different vapor-melt ratios(0.099,0.160,0.184,0.202), the observation result shows that high vapor-melt ratio can improve the kerf quality, enlarge the length of smooth zone of kerf surface and the striation wavelength, decrease the kerf surface roughness. Meanwhile the observation on samples of different thickness (0.8mm,1.0mm, 1.5mm,3mm) show that with the increasing of thickness, the vapor-melt ratio reduced, the kerf quality and roughness also decreased, the surface striation also presents different morphology. When the thickness is 0.8mm and 1.0mm, the surface presents smoothly periodic striation; When the thickness is 1.5mm, the surface presents two zones, which are smooth zone and rough zone; When the thickness is 3mm, the surface presents three zones, which are smooth zone, rough zone and scaled stack zone. The research on vapor-melt ratio and thickness can lead a deeper comprehension on the mechanism of laser cutting, provide theoretical and experimental basis for improving the laser cutting quality of zirconia ceramic.The removal of melt material has great effect on cutting quality during laser cutting, in order to understand the material removal mechanism profoundly, a set of processing device is designed to collect the melt particles. Imagine-Pro Pluse (IPP) is adopted to analyze the form(number, shape, mean and standard deviation and distribution) of particles. Laser cutting of zirconia ceramic with thickness of 0.8mm,1.0mm,1.5mm and 3mm, is carried out based on the vapor-melt ratio controlled. The results show that:under different thickness parameters, the percentage of spherical melt particles varies from 99.21% to 89.81%; the percentage of caky melt particles varies from 0.79% to 7.44%; the percentage of dumbbell melt particles varies from 0.79% to 7.44%. As the thickness increased, the percentage of spherical melt particles reduces, the percentage of caky and dumbbell melt particles increases, the mean and standard deviation of spherical melt particles diameter also goes up, the roughness of kerf surface adds from 2.287?m to 5.946?m. A geometric model of removal melt is established. The relation of melt particles and cutting quality is elaborated, which is the cutting quality improves with aggrandizement of spherical melt particles percentage and decrease of mean and standard deviation of spherical melt particles diameter.