CO_2レ-ザ-によるセラミックスの穴あけ加工

概要

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The hole drilling of Si\_3_N\_4_ by CO\_2_ laser is studied with and without assist gas flow and the thermal analysis of the process is carried out by FEM. The evaporated volume of Si\_3_N\_4_ by laser is proportional to the irradiation time and has small dependence on the flow rate of the assist gas. The increase of flow rate of assist gas makes deeper the depth of the drilled hole slightly, and also decreases its diameter. Cracks are observed on side walls, and on the bottom of the hole. The clacks grows longer with the increase of flow rate of the assist gas. Thermal analysis is applied to estimate the thermal stress caused by the laser irradiation. In the analysis the effect of mass evaporation is taken into account by taking the thrmal conduction coefficient larger in the hole. The predicted depth and the diameter of the drilled hole with time are shown to have good correspondence with experimental results. The thermal stress is estimated by the temperature predicted in the specimen by FEM. It predicts that the area, where cracks are experimentary observed, corresponds to the one where the stress is predicted higher than the critical stress of fracture.
長岡技術科学大学の論文