微波電子迴旋共振電漿浸入法在金屬基材上佈植氮離子及其性質分析

Abstract

摘要 本研究以電子迴旋共振微波電漿浸入離子佈植法分別對鈦、鋁、銅、七三黃銅、AISI D2模具鋼、AISI H13 模具鋼及AISI 304不□鋼等七種不同金屬基材施以離子佈植，藉由不同佈植能量及不同的佈植時間來探討各種不同基材表面佈植難易度及離子佈植後性質的變化。 在佈植能量方面，其加速電壓有15 kV和30 kV兩種條件，其電流值有1~2 mA和10mA兩種條件，就15 kV、1~2 mA佈植5小時而言，由RBS量測結果顯示，其佈植劑量約為1015 ions/cm2。此時之劑量略低於工業上常用之工具鋼硬化處理之劑量(約為1017 ions/cm2) ，因此預計硬化效果並不十分顯著，但在薄膜工程上可做為表面應變調節之作用。 對於基材佈植難易度而言，在15 kV、1~2 mA佈植5小時條件下，以表面層0.1□m以內之平均氮離子濃度作比較，結果顯示鋁、銅、七三黃銅、AISI D2模具鋼、AISI H13模具鋼、AISI 304不□鋼及鈦其濃度分別為7.30、1.44、2.38、9.99、13.35、7.06及12.89 at.% 。結果顯示銅系較不易佈植而AISI D2模具鋼和AISI H13模具鋼佈植後，其表面顏色無明顯變化，在空氣中一段時間以後其表面有明顯氧化現象而AISI 304不□鋼及鈦金屬其表面顏色在佈植後變成淡黃色，顯示可能有FexNy及TixNy膜形成。 在鈦金屬奈米機械性質方面，結果顯示經氮佈植後，其表面奈米硬度從原來的3.9 ~ 8.4 GPa提高至14.2 ~ 20.6 GPa，推導模數則由140 ~ 180 GPa提高至228 ~ 245 GPa表面各部磨潤性質之變化由平緩變成較陡峭佈植後之摩擦係數約為0.24 ~ 0.26之間。 在AISI-304不□鋼奈米機械性質方面，結果顯示經氮佈植後，其表面奈米硬度從原來的6.5 ~ 8.4 GPa提高至12.0 ~ 15.1 GPa，推導模數則由170 ~ 200 GPa提高至140 ~ 367 GPa表面各部磨潤性質則較無明顯之變化佈植後之摩擦係數約為0.41 ~ 0.56之間。 就電漿氣氛的影響，比較經N和N-H佈植後之成份及性質，AISI-304不□鋼之表面氮成份由7 at.%提升至34 at.%，奈米硬度變為12.4~15.8 GPa，推導模數為210~226 GPa，摩擦係數為0.34~0.38之間顯示添加H-電漿對機械性質沒有顯著影響。對鈦金屬之表面氮成份由7 at.%降至5 at.%，奈米硬度變為12.9~16.7 GPa，推導模數為120~145 GPa，摩擦係數為0.21~0.25之間顯示添加H-電漿對硬化效果有負面影響。添加Ar-電漿使表面氮含量明顯下降約7 at.%，此現象可能是Ar取代N之佈植效果，所以對鈦和AISI-304之機械性質無顯著影響。

ABSTRACT In this study, the ECR microwave plasma immersion ion implantation method was used to implant nitrogen ions on seven different substrate materials: Ti, Al, Cu, 70-30 Cu-Zn, AISI-D2, AISI-H13 and AISI-304. Effects of ion energy and implantation time on the extend of implantation and property variations of each substrates were examined. On ion energy of nitrogen, two different ion acceleration voltages ( 15 kV or 30 kV), and currents ( 1~2 mA or 10 mA) were adopted in this study. For the implantation conditions of 15 kV, 1~2 mA and 5 hr, the corresponding dosage of nitrogen ions is about 1015 ions/cm2 from RBS analyses. This value is lower than the minimum dosage of 1017 ions/cm2 for hardening of cutting tools in industrial applications. Therefore, a significant hardening effect is not expected. However, the process is intended to tune the strain states in thin film engineering applications. On the extend of implantation of each substrate, under the conditions of 15 kV, 1~2 mA and 5hr, the nitrogen concentrations of the layer within 0.1□m under surface are 7.30, 1.44, 2.38, 9.99, 13.35, 7.06 and 12.89 at.% for the substrates of Al, Cu, 70-30 Cu-Zn, AISI-D2, AISI-H13, AISI-304 and Ti, respectively. It signifies that nitrogen implantation on copper and copper alloys is more difficult. There are no significant color change after implantation for AISI-D2 and AISI-H13 substrates, but an obvious oxidation phenomenon can be observed within a short period of time. The surfaces of the implanted AISI-304 and Ti substrates are light yellow in color, probably implying formations of FexNy or TixNy films. On nano-mechanical properties of the implanted Ti, the nano-hardness is promoted from 3.9 ~ 8.4 GPa to 14.2 ~ 20.6 GPa; the reduced modulus from 140~180 GPa to 228~245 GPa; the distribution of tribological properties is varied from gradual to steep; and the friction coefficient is about 0.24 ~ 0.26 after implantation. On nano-mechanical properties of the implanted AISI-304,, the nano-hardness is promoted from 6.5 ~ 8.4 GPa to 12.0 ~ 15.1 GPa; the reduced modulus from 170 ~ 200 GPa to 140 ~ 367 GPa; but the distribution of tribological properties is not varied significantly; and the friction coefficient is about 0.41 ~ 0.56 after implantation. On effects of adding additional plasma sources, for AISI-304 substrate under N + H plasma, the concentration of surface nitrogen is increased from 7 at.% to 34 at.%; the nano-hardness becomes 12.4 ~ 15.8 GPa; the reduced modulus 210 ~ 226 GPa. The friction coefficient is about 0.34 ~ 0.38. It indicates that adding additional H-plasma has no significant effect on mechanical properties. For Ti substrate, the concentration of surface nitrogen is decreased from 7 at.% to 5 at.%; the nano-hardness becomes 12.9 ~ 16.7 GPa and the reduced modulus 120 ~ 145 GPa. The friction coefficient is about 0.21 ~ 0.25 after implantation. This shows that adding additional H-plasma has a detrimental effect on mechanical properties of the implanted Ti substrate. On effect of adding additional Ar-plasma, the surface concentration of nitrogen can be significantly reduced about 7 at.%. This may be due to substitution of N-effect by Ar ions, therefore, it causes no significant effects on mechanical properties of both the implanted Ti and AISI-304 substrates.