Studying Crack Generation Mechanism in Single-Crystal Sapphire During Ultra-precision Machining by MD Simulation-Based Slip/Fracture Activation Model
Studying Crack Generation Mechanism in Single-Crystal Sapphire During Ultra-precision Machining by MD Simulation-Based Slip/Fracture Activation Model
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DOI：
10.1007/s12541-023-00776-w
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发表时间：
2023-03
影响因子：
1.9
通讯作者：
S. Kwon;A. Nagaraj;Dalei Xi;Yiyang Du;Dae Nyoung Kim;Woo Kyun Kim;S. Min
中科院分区：
文献类型：
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作者：
S. Kwon;A. Nagaraj;Dalei Xi;Yiyang Du;Dae Nyoung Kim;Woo Kyun Kim;S. Min
单晶蓝宝石由于其上级的机械、光学和化学性质而用于工业的各个领域，但是由于其高硬度和脆性，制造蓝宝石具有挑战性。超精密加工（UPM）已被研究作为解决这些问题的解决方案之一，因为它有助于以韧性的方式切割脆性陶瓷。然而，在单晶蓝宝石的UPM过程中的材料去除机制尚未完全理解。本文研究了单晶蓝宝石在超微细加工过程中裂纹的形成机理，并与切割方向对蓝宝石晶体学性质的影响进行了对比。通过将分子动力学模拟得到的应力分布投影到不同的滑移面和断裂面上，计算了塑性变形和解理断裂的可能性，并确定了各自的裂纹萌生机制。通过沿着相同晶向的超精密正交插削实验验证了所提出的分子动力学模拟模型和分析。
Single-crystal sapphire is used in various fields of industry due to its superior mechanical, optical, and chemical properties, but fabricating sapphire is challenging because of its high hardness and brittleness. Ultra-precision machining (UPM) has been studied as one of the solutions to overcome these issues as it facilitates cutting of brittle ceramics in a ductile manner. However, the material removal mechanisms during UPM of single-crystal sapphire is not yet fully understood. This paper studied the crack initiation mechanism in single-crystal sapphire during UPM with relation to the crystallographic properties of sapphire depending on the cutting direction. By projecting a given stress distribution from molecular dynamics simulation on to different slip and fracture planes, the likelihood of plastic deformation and cleavage fracture was calculated, and respective crack initiation mechanisms were identified. The proposed MD simulation model and analysis were verified through ultra-precision orthogonal plunge cut experiments along the same crystallographic directions as the simulations.