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CO₂ 레이저 조사에 의한 질화규소 세라믹의 표면 변화 연구
김선원(S. W. Kim),이제훈(J. H. Lee),서정(J. Seo),조해용(H. Y. Cho),김관우(K. W. Kim) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.6
Silicon Nitride (Si₃N₄), which is widely used in a variety of applications, is hard-to-machine due to its high hardness. At high temperature (e.g. above 1000℃), however, the machinability can be greatly improved. In this work, we used a CO₂ laser with a high absorptivity to Si₃N₄ of 0.9 to locally heat the surface of a rotating Si3N4 rod on a lathe. In order to examine the effects of the laser-assisted heating on hardness, an Si₃N₄ rod is heated to temperatures from 900 to 1800℃ and is rotated at speeds from 440-900 rpm in experiments. When the rod is naturally cooled to room temperature, we measured the Vickers hardness (Hv); and observed the surface of HAZ using a scanning electron microscopy (SEM). Results showed that when heated at 1600 ℃, the hardness of Si₃N₄ decreased from 1500 Hv to 1000 Hv. Also, in order to predict the depth of HAZ, we numerically analyzed the laser-assisted heating of Si₃N₄.