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  • 學位論文

藉由鉬之添加以改善鉻鋁矽氮奈米複合晶薄膜的高溫磨耗性質

Improving high-temperature tribological characteristics in CrAlSiN nanocomposite coating by Mo doping

指導教授 : 杜正恭

摘要


表面工程乃係利用鍍覆薄膜於基材表面,以賦予和改善機件所需之特性,包括機械強度、抗氧化性、耐腐蝕性與耐磨耗性等等之性質,藉此提升其經濟價值或延長使用壽命,現已廣泛運用在各種工業領域中。在交通工具之渦輪系統中,零組件長時間在約攝氏540度之高溫中相互摩擦與磨損,為了降低摩擦所產生的熱量消耗以及增加各式零件的使用壽命,一個在高溫中具有良好抗磨耗與潤滑性質之薄膜正在被廣泛開發著。有鑑於此,本研究之目的乃是藉由不同成分之鉬元素的添加於鉻鋁矽氮奈米複合晶薄膜中,以製備出一擁有優秀高溫磨潤性質之薄膜。 本研究係利用磁控射頻濺鍍系統鍍製多元合金氮化物薄膜於特定基材,並以鉻鋁、矽以及鉬三靶槍共鍍之方法,藉由固定鉻鋁靶槍之功率以及控制矽把槍與鉬靶槍之功率比例,再透過通入氮氣進行反應,製備不同鉬含量之多元合金氮化物薄膜。由微結構鑑定中可發現,薄膜之晶體結構不會隨鉬含量的增加而改變,仍維持著原先鉻鋁矽氮奈米複合晶之緻密結構,同時在機械性質的表現上,仍舊保持原先良好的硬度與彈性係數,甚至在抗塑性變形率有著一定程度的提升。 本研究為了模擬機件在渦輪系統環境中之磨耗行為,以ball-on-disk之方式,在攝氏600度高溫中進行磨耗測試。結果顯示,添加之鉬含量越多,由於鉬之氧化物在高溫中的層狀結構提供的潤滑效果,使得薄膜之摩擦係數下降,但也因鉬氮相較弱的機械性質,導致磨耗率的些微上升。藉由電子能譜儀、掃描式及穿透式電子顯微鏡分析,可進一步整合不同鉬含量之薄膜,在高溫中抗磨耗之行為與特性。 總結上述,本研究結合鉬元素在高溫中特殊的潤滑效果,以及鉻鋁矽氮奈米複合晶薄膜優秀的機械和抗氧化性質,發展出在高溫中,一具有優良抗磨耗性質與自潤滑效果之薄膜系統。

並列摘要


Nanocomposite coatings have been widely used for protective coatings at high temperature owing to the superior mechanical strength over a broad operating temperature. However, there is still room for improvement on lubricating behavior of the coatings. Molybdenum is a promising candidate to further enhance the lubricating properties because of the layer crystal feature oxide. Therefore, this study attempts to investigate the influence of Mo in assisting mechanical and tribological properties. The Mo doped CrAlSiN coatings were deposited onto Inconel alloy 718 by radio frequency reactive magnetron co-sputtering. The tribological properties of CrAlSiN and CrAlMoSiN coatings were evaluated at 600 °C by ball-on-disc wear test. The reduced friction coefficient of coatings with increasing Mo content was revealed. The improvement of wear resistance was correlated with incorporating the formation of oxide into high-temperature tribological motion. Additionally, the parameter of the H3/E*2 regarded as the indicator of plastic deformation resistance was utilized to estimate the anti-wear property. The wear rate of CrAlMoxSiN coatings was roughly inversely related to the H3/E*2 ratio and the lowest wear rate existed in the coating with Mo of 14.5 at. % contents. It was demonstrated that anti-wear and lubricating capability of the coatings at elevated temperature could be improved by doping Mo. The merit could be used to provide feasibility for designing advanced high-temperature coatings via adjusting both of mechanical strengthening and oxide modifying by beneficial elements tuning in connection with properties of interest.

參考文獻


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