成份對於氮化鈦鋯硬膜之破裂靭性的影響

本研究的目的是利用自身能量誘發破裂方法來量測氮化鈦鋯硬膜的破裂靭性並研究成份對破裂靭性的影響，且藉此找到最佳靭性的成分區間。本研究選用三元氮化鈦鋯硬膜為模式材料，由於其在不同氮鈦比例下仍能保持單相的晶體結構。利用非平衡磁控濺鍍法沉積三種不同比例的氮化鈦鋯硬膜，分別為鋯/(鋯+鈦)=0.25、0.55、0.85，來探討成分對破裂靭性的影響。在自身能量誘發破裂方法中，殘留應力由光學曲率法測量、薄膜楊氏係數由奈米壓印獲得，而薄膜厚度由掃描式電子顯微鏡量測。由破裂前的殘留應力與膜厚可以計算出薄膜中的儲存能，當此儲存能足以產生裂縫時，其數值即為破裂靭性。實驗結果顯示氮化鈦鋯薄膜的破裂靭性隨鋯成分變化，其範圍在26.0 J/m2 到 48.7 J/m2；在鋯/(鋯+鈦)達0.85時，破裂靭性達最大值48.7 J/m2。添加鋯原子進入氮化鈦中有利增加破裂靭性，而鈦與鋯原子的大小差異在增加破裂靭性上扮演重要的角色。再者發現在富鋯端的氮化鈦鋯薄膜增加破裂靭性的程度大於富鈦端，其成因可能是由於薄膜可以儲存應變能的能力不同。自身能量誘發破裂方法可以適用於破裂發生於薄膜之中，但若裂縫延伸到基板，則基板破裂的能量須納入破裂靭性的考慮。

關鍵字

破裂靭性；氮化鈦鋯硬膜

並列摘要

The objectives of this study were to measure the fracture toughness of Ti1-xZrxN hard coatings using the internal energy induced cracking (IEIC) method and investigate the effect of composition on the fracture toughness, from which the optimum composition for fracture toughness could be attained. Ti1-xZrxN was selected to be the model system, because Ti1-xZrxN remained single phase structure in the entire compositional range when deposited at temperatures below 500 C. Three compositions of Ti1-xZrxN, x=0.25, 0.55 and 0.85, were deposited by unbalance magnetron sputtering (UBMS). The IEIC method involved the residual stress measured by the laser curvature method, Young’s modulus obtained from nanoindentation and the film thickness from SEM cross-sectional image. The residual stress and film thickness before specimen fracture were used to determine the elastic stored energy (Gs), from which the fracture toughness could be derived. The resultant fracture toughness of Ti1-xZrxN varied with Zr fraction, ranging from 26.0 to 48.7 J/m2, and reaching a maximum for Ti0.15Zr0.85N. Adding Zr atoms into TiN could effectively increase the fracture toughness. The atomic size difference of Zr and Ti may play an important role on increase of fracture toughness. The increase of fracture toughness for Ti0.15Zr0.85N was higher than that for Ti0.75Zr0.25N. This asymmetrical behavior could be attributed to the difference in lattice constants between Ti-rich and Zr-rich compounds, in which the capability of increasing elastic stored energy may be higher for a smaller Ti atom incorporate into a larger ZrN lattice. It is also found that IEIC method can be applied as long as the cracking occurs inside the film. If the cracks penetrate into the substrate, the contribution of substrate cracking should be considered.

並列關鍵字

Fracture toughness ； Ti1-xZrxN hard coating

參考文獻

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國際替代計量

成份對於氮化鈦鋯硬膜之破裂靭性的影響

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