Mughal Muhammad Zeeshan, Amanieu Hugues-Yanis, Moscatelli Riccardo, Sebastiani Marco
Engineering Department, University of Rome "ROMA TRE", Via della Vasca Navale 79, 00146 Rome, Italy.
Institute for Materials Science and Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, Universitätsstr. 15, 45141 Essen, Germany.
Materials (Basel). 2017 Apr 12;10(4):403. doi: 10.3390/ma10040403.
Accurate estimation of fracture behavior of commercial LiMn₂O₄ particles is of great importance to predict the performance and lifetime of a battery. The present study compares two different microscale techniques to quantify the fracture toughness of LiMn₂O₄ particles embedded in an epoxy matrix. The first technique uses focused ion beam (FIB) milled micro pillars that are subsequently tested using the nanoindentation technique. The pillar geometry, critical load at pillar failure, and cohesive FEM simulations are then used to compute the fracture toughness. The second technique relies on the use of atomic force microscopy (AFM) to measure the crack opening displacement (COD) and subsequent application of Irwin's near field theory to measure the mode-I crack tip toughness of the material. Results show pillar splitting method provides a fracture toughness value of ~0.24 MPa.m, while COD measurements give a crack tip toughness of ~0.81 MPa.m. The comparison of fracture toughness values with the estimated value on the reference LiMn₂O₄ wafer reveals that micro pillar technique provides measurements that are more reliable than the COD method. The difference is associated with ease of experimental setup, calculation simplicity, and little or no influence of external factors as associated with the COD measurements.
准确估计商用LiMn₂O₄颗粒的断裂行为对于预测电池的性能和寿命至关重要。本研究比较了两种不同的微观尺度技术，以量化嵌入环氧树脂基体中的LiMn₂O₄颗粒的断裂韧性。第一种技术使用聚焦离子束（FIB）铣削的微柱，随后使用纳米压痕技术进行测试。然后利用柱体几何形状、柱体失效时的临界载荷以及内聚有限元模拟来计算断裂韧性。第二种技术依靠使用原子力显微镜（AFM）来测量裂纹开口位移（COD），并随后应用欧文近场理论来测量材料的I型裂纹尖端韧性。结果表明，柱体劈裂法提供的断裂韧性值约为0.24MPa·m，而COD测量给出的裂纹尖端韧性约为0.81MPa·m。将断裂韧性值与参考LiMn₂O₄晶片上的估计值进行比较，结果表明微柱技术提供的测量结果比COD方法更可靠。这种差异与实验设置的简易性、计算的简便性以及与COD测量相关的外部因素影响很小或没有影响有关。
