本研究的目的是研究使用高功率脈衝磁控濺鍍法於D2鋼基材製備γ-氮化鉬/鉬雙層鍍層中鉬金屬介層之功能。介層厚度控制在50到150奈米之間，氮化鉬鍍層的厚度控制在1000奈米。實驗結果表明鉬金屬介層的添加對於氮化鉬薄膜的化學成分、微結構以及機械性質都沒有顯著影響。
本實驗使用兩種不同方法量測雙層鍍層的殘餘應力。雷射光學曲率法用以量測矽基材上薄膜的整體應力，平均X光應變法用以量測各層內的應力。對於鍍著於矽基板上的試片，其介層內的壓應力要高於上層的氮化鉬薄膜，同時也超過了鉬的降伏強度（σy,Mo），這不同於預期的金屬介層通過塑性變形釋放應力的功能。對鍍著於D2鋼基材的試片，量測結果顯示鉬介層的應力非常高，超過其六倍的降伏強度，這表示鉬介層已經無法通過塑性變形釋放應力。鉬介層反而是作為氮化鉬與D2鋼基材之間的過渡層，將氮化鉬的應力傳遞到D2鋼基材中，再由介面附近的D2鋼通過塑性變形釋放應力。應力釋放的程度則與鉬介層的厚度相關。鉬的高強度係數與應變硬化指數可能是導致鉬介層無法作為緩衝層，而是成為過渡層的原因。
所有試片的磨耗率都很低，其主要原因可能是Magnéli氧化相的生成。實驗結果顯示鉬金屬介層的加入可以強化氮化鉬在D2鋼基材上的附著強度，但由於其附著強度在磨耗測試中顯示本身就已足夠，因此添加介層的實用性不大。再者，加入厚度不足的鉬介層也無益於氮化鉬薄膜的應力釋放。

The purpose of this study was to investigate the function of Mo metal interlayer in the γ-Mo2N/Mo bilayer coatings deposited by high power pulsed magnetron sputtering (HPPMS) on D2 steel substrate. The interlayer thickness was designed from 50 to 150 nm, and the thickness of γ-Mo2N was controlled at 1000 nm. The results indicated no significant change in chemical compositions, microstructure, and mechanical properties of the Mo2N coatings by adding a Mo interlayer. The residual stress of the bilayer coatings was measured by two methods. Laser curvature method was applied to measure the overall stress of the bilayer samples on Si substrate. The stress in individual layers was measured by the average X-ray strain method. For samples on Si substrate, the compressive stress in Mo interlayer was higher than that of the Mo2N coating, which was also far higher than the yield strength of Mo (σy,Mo). This is quite different from the expected function that the interlayer can relieve stress by plastic deformation. The stress measurements on samples on D2 steel substrate showed that the Mo interlayer is under a very high compressive stress (> 6σy,Mo), indicating that the interlayer cannot relieve stress by plastic deformation. Instead, the interlayer serves as a transitional layer that transfers the stress in Mo2N to D2 steel substrate, where the D2 steel near the interface relieve the stress by plastic deformation, and the extent of stress relief is related to the interlayer thickness. The high strength coefficient and strain hardening exponent may be the reason that Mo cannot serve as a buffer layer but become a transitional layer. All samples show quite low wear rate, where the formation of the self-lubricating Magnéli oxides may be the major factor. Although the Mo interlayer can increase the adhesion strength of Mo2N coating on D2 steel substrate, it is not necessary to add a Mo interlayer because the adhesion strength of Mo2N on D2 steel substrate is sufficient for the wear test. Moreover, adding a Mo interlayer with inadequate thickness (50 nm) may not be beneficial to the stress relief of the Mo2N coatings.

Abstract i
摘要. ii
致謝. iii
Content v
List of Figures viii
List of Tables x
Chapter 1 Introduction 1
Chapter 2 Literature Review 3
2.1 Characteristic of Molybdenum Nitride 3
2.2 Crystal Structure of Molybdenum Nitride 4
2.3 Effects of Metal Interlayer on Coatings 5
2.4 High Power Pulsed Magnetron Sputtering (HPPMS) 7
2.5 Effects of Process Parameters 9
2.5.1 Duty Cycle 9
2.5.2 Working Pressure 10
2.5.3 Nitrogen Flow Rate 11
2.6 Tribological Behavior 11
2.6.4 Wear Resistance 11
2.6.5 Adhesion Strength 13
2.6.6 Self-lubrication of Molybdenum nitride 13
Chapter 3 Experimental Details 15
3.1 Experimental design 15
3.2 Substrate Preparation 15
3.3 Deposition Procedures 16
3.4 Characterization of Composition and Structure 20
3.4.1 Chemical Compositions 20
3.4.2 Compositional Depth Profile 20
3.4.3 Compositions in the Wear Track 20
3.4.4 Crystal Structure 21
3.4.5 Surface Morphology and Cross-sectional Microstructure 22
3.4.6 Surface Roughness 22
3.5 Characterization of Properties 23
3.5.1 Hardness and Young’s Modulus 23
3.5.2 Residual Stress 24
3.5.2.1 Laser Curvature Method (LCM) 24
3.5.2.2 Average X-ray Strain (AXS) Method 25
3.5.3 Thermal Stress 26
3.5.4 Electrical Resistivity 26
3.5.5 Wear Resistance 28
3.5.6 Adhesion Strength 29
Chapter 4 Results 31
4.1 Plasma Compositions and Peak Power Density 31
4.1.1 Plasma Compositions 31
4.1.2 Peak Power Density 33
4.2 Chemical Compositions and Structure 34
4.2.1 Chemical Compositions 34
4.2.2 Crystal Structure 35
4.2.3 Microstructure 35
4.2.4 Surface Roughness 36
4.3 Mechanical Properties 41
4.3.1 Hardness, Young’s Modulus and Electrical Resistivity 41
4.3.2 Residual Stress 41
4.3.3 Wear Resistance 46
4.3.4 Adhesion Strength 50
Chapter 5 Discussion 53
5.1 Effects of Mo Interlayer on Residual Stress 53
5.1.1 Residual Stress of the Samples on Si Substrate 53
5.1.2 Residual Stress of the Samples on D2 Steel Substrate 54
5.2 Effects of Mo Interlayer on Tribological Behavior 57
Chapter 6 Conclusions 59
References 60
Appendix A 68
Appendix B 69

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