鮑魚珍珠層是一種有機無機混成的天然複合材料，有95%以上是由碳酸鈣組成以及少量的生物高分子，具有高強度及高破裂韌性。碳酸鈣本身具有高硬度但破裂韌性低，而其韌性強度主要歸功於特殊的多層結構。當鮑魚殼受到外力作用時，由於多層結構的關係，裂縫並不會一次性的破裂，而會被層狀結構偏折甚至阻擋。此外，層狀微結構間的粗糙界面使其受外力作用時不易產生形變。有鑑於此，本研究利用磁控濺鍍以及脈衝雷射沉積來合成仿鮑魚珍珠層結構的有機及無機複合材料之高韌性多層薄膜，所選用的材料為氧化鋯以及聚醯亞胺。氧化鋯本身具有不俗的破裂韌性，在引入有機的聚醯亞胺界面後，其破裂韌性相較於氧化鋯單層模獲得六倍的大幅的提升。氧化鋯以及聚醯亞胺的厚度比固定為十比一，並改變其週期厚度來探討機械性質的改變，如硬度及破裂韌性。本研究內容指出，多層膜的結構能夠使薄膜的破裂韌性提升；多層膜的層數會與薄膜的機械性質有關，層數越多韌性越佳，相對地硬度會下降。由電子顯微鏡的觀察驗證仿生多層膜之韌化機制主要為有機層與無機層界面造成裂縫偏折，無法直接斷裂。多層膜的介面粗糙度是另一影響機械性質的因素，在提升介面粗糙度之後，某些情況下薄膜的硬度與破裂韌性會有所提升，其機制於本研究深入地分析討論。

Abalone nacre is a natural ceramic-based composite consists of 95 wt% stacked CaCO3 tiles and 5 wt% organic layers organized into a unique multilayer structure, which leads to exceptional fracture toughness. The major toughening mechanism is the crack deflection at the organic/inorganic interfaces so that the crack cannot propagate through the shell directly. Furthermore, interfacial roughness and interconnected mineral bridges between tiles can further prevent plastic deformation. Inspired from abalone nacre, multilayer films of zirconia and polyimide layers are synthesized by the hybrid PVD system combining sputtering and pulsed laser deposition. Zirconia is an intrinsically tough ceramic material. By introducing the polyimide interlayer, the fracture toughness of multilayer films can be significantly enhanced, six times higher than that of zirconia monolayer. The thickness ratio of zirconia and polyimide is kept 10:1, and the period thickness is altered to investigate effect the interfaces on the mechanical properties. Results show that multilayer structure can enhance the fracture toughness of thin film: fracture toughness increases with increasing number of interlayers yet the hardness decreases. SEM observation verifies that the major toughening mechanism of bio-inspired multilayer films is crack deflection at organic/inorganic interfaces, which prevent crack from direct propagation. The interfacial roughness can also enhance mechanical properties in certain situations and the mechanisms are discussed.

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