基于数值仿真和实验研究了Al₂O₃陶瓷激光选区熔化(SLM)成形表面凝固组织的形成机理。结果表明:Al₂O₃陶瓷SLM成形具备发生贝纳德-马兰戈尼表面失稳的条件,随着激光能量减小,对流接近稳态;基板预热能够改变贝纳德-马兰戈尼对流状态;低激光功率、快扫描速度、低预热温度有助于形成稳态液体表面的层流流动。

On the basis of numerical simulation and experiments, the formation mechanism of solidification microstructures on the alumina ceramic surface by selective laser melting (SLM) is clarified. The research results show that as for the SLM of alumina ceramic, the forming condition of Bénard-Marangoni surface instability is satisfied. As laser energy decreases, the convection is close to its steady state. The preheating of substrate can change the Bénard-Marangoni convection state. Low laser power,fast scanning speed and low preheating temperature are all beneficial to the formation of a steady laminar flow on the liquid surface.