甲殼類的外骨骼是由天然的幾丁質及蛋白質複合材料所構成，藉由機械性質的梯度變化來提供其優越的強度以及破裂韌性。其主要的韌性強化機制為裂縫在堅硬外表皮與強韌內表皮之間的介面偏折，使得裂縫不易直接擴散進整個外骨骼中。此外，內表皮擁有旋轉的夾板結構(Bouligand structure)以形成週期性的彈性模數變化來阻擋裂縫前進並進一步強化其破裂韌性。有鑑於此，本研究利用射頻磁控濺鍍以及雷射蒸鍍沉積複合系統來鍍製陶瓷及高分子多層仿生薄膜。為了模仿甲殼類外骨骼中的上表皮與下表皮的性質，利用氧化鋯堅硬外層以及週期性堆疊氧化鈦與聚醯亞胺強韌內層來製備高韌性複合薄膜。其中，氧化鈦與聚醯亞胺多層膜的厚度比例固定在10比1 (100 nm:10 nm)，並藉由改變氧化鋯的厚度，從100 nm到500 nm來探討彈性模數梯度變化對薄膜機械性質的影響。量測方面，奈米壓痕儀被使用來量測多層膜的機械性質。而仿生薄膜的破裂韌性量測則是由壓痕法來製造裂縫並藉由能量計算來得到薄膜破裂韌性。研究結果顯示，特定厚度比例的氧化鋯外層可以有效地提升薄膜破裂韌性，其韌性強化機制以及仿生設計會在此研究中分析討論。

Crustacean exoskeleton, a natural composite consisting of chitin, proteins and minerals, has gradient constituent and microstructure which provide excellent hardness and fracture toughness. The major toughening mechanism is the crack deflection at the interface between the hard exocuticle and tough endocuticle so that the crack cannot propagate through the exoskeleton directly. The twisted plywood (or Bouligand) structure which possesses elastic modulus mismatch and oscillation could further prevent cracks from propagation. A novel hybrid system combining reactive RF sputtering and pulsed laser deposition is designed and utilized to synthesize bio-inspired ceramic/polymer multilayer coatings. In order to mimic the exocuticle and endocuticle in crustacean exoskeleton, multilayer coatings composed of hard ZrO2 outer layers and tough TiO2/polyimide inner layers were synthesized. The thickness ratio of TiO2/polyimide layers is kept 10 to 1 (100 nm/10 nm), and the thickness of ZrO2 was altered from 100 nm to 500 nm to investigate the effect of the elastic modulus gradient on the mechanical properties. Nanoindentation was conducted to evaluate the mechanical performance of multilayer films. The fracture toughness of bio-inspired coatings was further evaluated by the energy-based indentation method. Results show that the multilayer film with specific thickness ratio of ZrO2 has the highest fracture toughness. Toughening mechanisms were elucidated and optimal bio-inspired designs were proposed in this study.

中文摘要 I
Abstract II
Contents III
Figure Caption VII
Chapter 1 Introduction 1
Chapter 2 Literature Review 4
2.1 Overview – Nature Armors 4
2.2 Characteristics of Biological Materials 5
2.3 Functional Adaptation and Mechanical Properties of Biomaterials 8
2.4 Crustacean Exoskeletons 10
2.4.1 Hierarchical Structure 11
2.4.2 Mechanical Properties 12
2.5 Thin Film Technique 13
2.5.1 Reactive Sputtering 13
2.5.2 Pulsed Laser Deposition 15
2.5.3 Hybrid PVD System 17
2.5.4 Hard Coatings 18
2.5.5 Multilayer Coatings 19
2.6 Fracture Toughness 21
2.6.1 Indentation Plasticity 22
2.6.2 Scratch Toughness 23
2.6.3 Toughness Evaluation from Radial Crack 24
2.6.4 Substrate Indentation Method 25
2.6.5 Circumferential Cracking and Spallation 26
2.6.6 Micro-tensile Testing for Standalone Thin Films 27
2.7 Impact Resistance 28
Chapter 3 Experimental Procedure 54
3.1 Hybrid Physical Vapor Deposition System 54
3.2 Substrate Preparation 55
3.3 Sputtering 55
3.4 Pulsed Laser Deposition 56
3.5 Microstructural Characterization 57
3.6 Phase Identification 57
3.7 Mechanical Properties Evaluation 58
3.7.1 Hardness and Elastic Modulus 58
3.7.2 Fracture Toughness 58
3.7.3 Impact Resistance 60
Chapter 4 Results and Discussion 71
4.1 Optimization of Hybrid PVD System 72
4.1.1 Monolayer Films 73
4.1.2 Multilayer Films 75
4.1.3 Summary 77
4.2 Phase Identification and Composition Analysis of Monolayer Films 78
4.2.1 Zirconia Film and Titania Films 78
4.2.2 Polyimide Film 79
4.3 Microstructural Design and Synthesis of Multilayer Films 80
4.4 Hardness Evaluation 82
4.5 Elastic Modulus Evaluation 83
4.6 Impact Resistance Evaluation 83
4.6.1 Impact Resistance of ZrO2/TiO2 Bilayer Films 84
4.6.2 Impact Resistance of TiO2/PI Multilayer Films 86
4.6.3 Impact Resistance of Exoskeleton-inspired Multilayer Film 87
4.7 Fracture Toughness Measurement and Toughening Mechanism 89
4.7.1 Microindentation 90
4.7.2 Fracture Toughness Evaluation 90
Chapter 5 Conclusions 108
Chapter 6 Future Work 110
6.1 Improvement of Film Qualities 110
6.2 Enhancement of Corrosion Resistance 111
6.3 Modification of Fracture Toughness Evaluation 111
References 113

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