脉冲激光作用Al2O3的表面形貌演变过程

激光表面加工是一种能够有效降低陶瓷材料表面粗糙度的方法，为了研究脉冲激光与陶瓷材料作用后表面形貌演变过程及激光工艺参数对表面粗糙度的影响，本文通过有限元法建立了瞬态二维轴对称数值模型，研究了单脉冲、多脉冲激光作用于氧化陶瓷表面形貌的演变过程及激光工艺参数对表面粗糙度的影响。结果表明：单脉冲激光对材料表面具有显著的平滑效果；多脉冲激光加工在脉冲2～3次时具有最好的平滑效果，继续增加脉冲数量，熔池内的表面轮廓开始向下凹陷，表面平滑效果减弱；采用不同工艺参数加工时，过大的频率、脉宽、激光功率都会导致材料表面粗糙度增加。当表面温度处于熔化温度与蒸发温度之间，熔池内流体以毛细力为主要驱动力，促使表面逐渐平滑；当表面温度超过蒸发温度时，熔池内流体受反冲压力挤压，促使表面粗糙。实验与模拟结果对比表明，该模型具有较高的准确性。

Surface morphology evolution of Al2O3 irradiated by pulsed laser

Laser surface processing is an effective method to reduce the surface roughness of ceramic materials. In order to study the evolution of surface morphology and the influence of laser process parameters on the surface roughness after the interaction of pulsed laser on ceramic materials, a transient two-dimensional axisymmetric numerical model is established by finite element method to study the evolution of surface morphology of single-pulse and multi-pulse laser on oxide ceramics and the influence of different laser process parameters on the surface roughness. The effects of single-pulse and multi-pulse lasers on the surface morphology of oxide ceramics and the effects of different laser process parameters on the surface roughness were studied. The results show that single-pulse laser has a significant smoothing effect on the material surface; multi-pulse laser processing has the best smoothing effect at two to three pulses, and when the number of pulses continues to increase, the surface profile in the melt pool starts to sink down and the surface smoothing effect is weakened; when different process parameters are used, excessive frequency, pulse width and laser power will lead to the increase of material surface roughness. When the surface temperature is between the melting temperature and the evaporation temperature, the fluid in the melt pool is driven by the capillary force, which makes the surface smooth gradually; when the surface temperature exceeds the evaporation temperature, the fluid in the melt pool is squeezed by the recoil pressure, resulting in surface roughness. The comparison of experimental and simulation results shows that the model has high accuracy.