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  • 學位論文

氮化鈦硬膜破裂韌性量測

Fracture Toughness Measurement on TiN Hard Coating

指導教授 : 黃嘉宏 喻冀平
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摘要


許多研究團隊致力於建構量測薄膜破裂韌性規範,然而至今仍未有一套標準量測機制。現有的方法主要為基於應力計算或能量差兩類;但是這些方法都需要外加應力,因此必須設計特殊幾何形狀之基材,或精細的微米尺寸薄膜應變計,或需要製造原子等級銳利的預裂縫。其中多數方法都難以避免基材效應,且必須事先量測殘留應力分布,或是在外加應力的環境之下,即時量測薄膜內應力分布。這些需求條件都成為建立量測方法的困難所在,因此本研究目的是嘗試建立一個無需外加應力的破裂韌性量測方法,此法可以適用於具有殘餘應力之硬膜。由於氮化鈦薄膜有相當良好的機械性質與等向性,因此本研究選擇氮化鈦薄膜作為模式材料。 依據Griffith’s 能量理論,裂縫前進由薄膜內之應變能釋放而驅動。利用裂縫生成前後之應力變化量即可計算膜內平均儲存能(Gs),當此儲存能足以產生裂縫時,其數值即為破裂韌性。本研究所提出之破裂韌性量測方法包含X光繞射之應力與應變量測,雷射曲率應力量測,並以奈米壓印量測楊氏係數。應力梯度的量測中,彈性常數使用平均有效X光彈性常數(AEXEC),以減少因統計造成的應力梯度誤差。本實驗成功的量測氮化鈦鍍膜之破裂韌性,16.7 J/m2,與前人研究結果相較,本實驗之數值落在一合理的範圍內。本研究並結合cos2αsin2ψ X光繞射應力量測法與分層(layer by layer)應力解析,得到一積分儲存能(GIS)。此積分儲存能可代表局部能量分布並與裂縫成長形式相關。本實驗提出兩個能量參數:GS與GIS,GS可用於量測硬膜之破裂韌性,而GIS分布則可用於預測裂縫成長的趨勢。薄膜厚度也可應用破裂韌性與GS的公式控制。此外,本實驗中所提出一個新的X光彈性常數結合楊式常數與普松比,AEXEC成功的改善了X光量測中的統計誤差,以增加樣本總量的觀念,減低來自X光應變量測的誤差,並提供了一個簡單可靠的X光彈性常數用於殘留應力梯度量測

關鍵字

破裂韌性 硬膜 氮化鈦

並列摘要


In last two decades, extensive studies have been dedicated in establishing a standard method on toughness measurement for thin film materials. However, there has no standard methodology or test procedure up to now. Stress based or energy based methods have been proposed on this subject, where the externally applying stress is usually required, and therefore special substrate geometry is designed, or micro-scaled strain gauge or atomically sharp cracks need to be fabricated. In addition, the stress distribution in the specimen should be monitored during the measurement. These requirements may introduce the complicated substrate effect and thereby increasing the difficulty of fracture toughness measurement. This research was in an attempt to develop a new method without applying external stress for measuring fracture toughness of hard coatings. TiN was selected as a model material, owing to its well-established mechanical properties and nearly elastic isotropy. The proposed method involved residual stress measurements by XRD and laser curvature methods, and Young’s modulus obtained from nanoindentation. The difference of stress before and after crack initiation was used to evaluate the average storage energy (Gs), from which fracture toughness was derived. The results showed that the fracture toughness of random-textured TiN coatings was 16.7J/m2, which is comparable to previous reported data. The integrated stored energy (GIS) was assessed from Gs by considering the stress gradient measured from cos2αsin2ψ XRD method accompanying with layer-by-layer analysis. GIS can be regarded as the local energy distribution and is a guidance of local fracture location. GIS distribution was found to be consistent with the fracture morphologies of the coatings. Furthermore, the fracture toughness can be used to determine the critical thickness which is useful in thickness control. A new elastic constant named AEXEC (average effective X-ray elastic constant) was suggested, which can reduce the statistical fluctuation in stress measurement. The AEXEC also provides a simple and nondestructive way to acquire reliable XECs that are comparable to those determined by nanoindentation.

並列關鍵字

fracture toughness hard coatings TiN

參考文獻


[97] 陳威戎, 黃嘉宏, 喻冀平, 磁控濺鍍鈦-矽-氮奈米複合膜之機械性質研究 = The Mechanical Properties of Ti-Si-N Nanocomposite Films Deposited by Magnetron Sputtering, 新竹市, 國立清華大學.
[82] J.M. Pureza, M.M. Lacerda, A.L. De Oliveira, J.F. Fragalli, R.A.S. Zanon, Enhancing accuracy to Stoney equation, Applied Surface Science 255 (2009) 6426-6428.
[1] S. Zhang, D. Sun, Y. Fu, H. Du, Toughness measurement of thin films: a critical review, Surface and Coatings Technology 198 (2005) 74-84.
[2] G. Gille, Investigations on Mechanical-Behavior of Brittle Wear-Resistant Coatings .2. Theory, Thin Solid Films 111 (1984) 201-218.
[3] G. Gille, K. Wetzig, Investigations on Mechanical-Behavior of Brittle Wear-Resistant Coatings .1. Experimental Results, Thin Solid Films 110 (1983) 37-54.

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