Chen Jung-Hsuan, Luo Wen-Shiang
Department of Industrial Education, National Taiwan Normal University, 162, Sec.1, Heping E. Rd., Taipei 106, Taiwan.
Passive BU Department, Cyntec Company, 2, Yanfa 2nd Rd., Hsinchu 300, Taiwan.
Micromachines (Basel). 2017 Jun 27;8(7):206. doi: 10.3390/mi8070206.
This study investigated the influence of porosity on the flexural property of a nanoporous alumina film. When the porosity of the alumina film increased, both bending strength and modulus declined. The results from the bending test revealed that the setting of the film during the bending test had significant influence on the flexural property. Fracture only occurred when the porous side of the alumina film suffered tensile stress. The ability to resist fracture in the barrier layer was higher than in the porous side; the magnitude of the bending strength was amplified when the barrier layer sustained tensile stress. When the porous layer suffered a tensile stress, the bending strength decreased from 182.4 MPa to 47.7 Mpa as the porosity increased from 22.7% to 51.7%; meanwhile, the modulus reduced from 82.7 GPa to 17.9 GPa. In this study, the most important finding from fractographic analysis suggested that there were a localized plastic deformations and layered ruptures at the porous side of the alumina film when a load was applied. The fracture behavior of the nanoporous alumina film observed in the present work was notably different from general ceramic materials and might be related to its asymmetric nanostructure.
本研究调查了孔隙率对纳米多孔氧化铝薄膜弯曲性能的影响。当氧化铝薄膜的孔隙率增加时，弯曲强度和模量均下降。弯曲试验结果表明，薄膜在弯曲试验中的设置对弯曲性能有显著影响。仅当氧化铝薄膜的多孔侧承受拉应力时才会发生断裂。阻挡层的抗断裂能力高于多孔侧；当阻挡层承受拉应力时，弯曲强度的幅度会增大。当多孔层承受拉应力时，随着孔隙率从22.7%增加到51.7%，弯曲强度从182.4 MPa降至47.7 Mpa；同时，模量从82.7 GPa降至17.9 GPa。在本研究中，断口分析最重要的发现表明，施加负载时，氧化铝薄膜的多孔侧存在局部塑性变形和分层破裂。在本工作中观察到的纳米多孔氧化铝薄膜的断裂行为与一般陶瓷材料明显不同，可能与其不对称纳米结构有关。
