G1301-1-1 単結晶ダイヤモンドのレーザ加工メカニズムに関する研究(生産加工・工作機械一般)

概要

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When a Nd : YAG laser, the wavelength of which is permeable for diamond, is focused on the surface of a diamond sample, a layer of surface material is ablated. Therefore, diamond can be cut by repetitive irradiation. In this study, the processing mechanism of ablation for a single crystal diamond was examined using a heat conduction analysis, considering laser absorption at the surface or the temperature dependence of absorption coefficient. When the laser beam is absorbed at the surface layer, the surface layer is ablated during an early period in the laser pulse. Once the absorption surface layer is ablated, the laser beam penetrates the base material and ablation stops. On the other hand, if we assume single crystal diamond has the temperature dependence of absorption coefficient which is about equal to that of CVD diamond, the temperature rise is not enough to ablate the material. However, it became clear that the diamond is ablated deeply when we consider both absorption at the surface layer and the temperature dependence of the absorption coefficient. It can be considered that the surface is transformed to graphite and becomes the absorption layer during the repetitive irradiation. It is estimated that the phase change to graphite is very small and its volume fraction is about one percent.
社団法人日本機械学会の論文
2009-09-12