SiO_2の環境助長割れ進展挙動の原子レベルシミュレーション(<小特集>電子機器の熱・機械信頼性と機械工学)

概要

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A modified extended Tersoff interatomic potential function is proposed in order to simulate the environment-assisted crack propagation behavior. Firstly, the physical properties of Si, O_2, H_2, SiO_2, and H_2O are calculated by this modified function. It is confirmed that these calculated values agree with the measured values very well. Next, the potential surface of H_2O molecular transporting process to the crack tip of SiO_2 material is calculated by the same function. The relationship between the velocity of crack propagation "v" and stress intensity factor "K" is calculated based on this surface. The results agree with the experimental results well. From this simulation, it is clarified that the crack velocity is controlled by H_2O transporting process in the both region I and II of "v-K curve". In the region I, H_2O molecules have physically limited access to the crack tip due to the small opening of the crack. This works as energy barrier in transporting H_2O molecules. Due to the relatively large crack opening, in the region II, H_2O molecules have free access to the crack tip without energy barrier. This difference makes a bend in "v-K curve" between region I and II.
一般社団法人日本機械学会の論文
2009-07-25