甲殼類外殼之仿生啟發:以濺鍍與脈衝雷射蒸鍍複合系統合成氧化鋯與氧化鈦/聚亞醯胺多層鍍膜之研究

Bio-inspirations from Crustacean Exoskeletons: Investigations on the ZrO2 and TiO2/PI Multilayer Coatings Synthesized by a Hybrid Sputtering and Pulsed Laser Deposition Technique

徐宗豪(Tsung-Hao Hsu)

指導教授 ： 陳柏宇

國立清華大學/工學院/材料科學工程學系/碩士(2015年)

摘要

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。

關鍵字

仿生 ； 外骨骼 ； 多層薄膜 ； 濺鍍 ； 脈衝雷射沉積 ； 機械性質 ； 韌性強化機制

並列摘要

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.

並列關鍵字

bio-inspiration ； exoskeleton ； multilayer coatings ； sputtering ； pulsed laser deposition ； mechanical properties ； toughening mechanisms

參考文獻

[6] M. A. Meyers, P.-Y. Chen, A. Y.-M. Lin, and Y. Seki, "Biological materials: Structure and mechanical properties," Progress in Materials Science, vol. 53, pp. 1-206, 2008.

[1] Z. Burghard, L. Zini, V. Srot, P. Bellina, P. A. van Aken, and J. Bill, "Toughening through Nature-Adapted Nanoscale Design," Nano Letters, vol. 9, pp. 4103-4108, Dec 2009.

[2] P.-Y. Chen, J. McKittrick, and M. A. Meyers, "Biological materials: Functional adaptations and bioinspired designs," Progress in Materials Science, vol. 57, pp. 1492-1704, 2012.

[3] M. A. Meyers, J. McKittrick, and P. Y. Chen, "Structural biological materials: critical mechanics-materials connections," Science, vol. 339, pp. 773-9, Feb 15 2013.

[4] J. Shigley, C. Mischke, and T. Brown, “Standard Handbook of Machine Design.” McGraw-Hill, 2004.