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Tribological and mechanical properties of carbon nitride films on WC-Co substrates by RF-PECVD
|Authors: ||Yao-Chia Chu|
|Contributors: ||NTOU:Department of Mechanical and Mechatronic Engineering|
Carbon nitride films;PECVD;WC-Co;oxidation
|Issue Date: ||2011-11-23T03:16:15Z
|Abstract: ||本論文以射頻電漿輔助化學氣相沉積系統研究在具有非晶矽中間層之燒結碳化鎢底材上被覆含氮碳膜的機械性質與氧化特性。實驗參數固定射頻功率，調整CH4與N2比例，以及工作壓力製備含碳氮膜。接著將實驗對象分成原始參數以及經過低氧分壓實驗後之試片。之後由表面輪廓儀量測其膜厚，可發現工作壓力與沉積速率成正比，而拉曼光譜儀、傅立葉轉換紅外光譜儀、X光光電子能譜儀與場發射電子微探儀則分析在不同參數與不同溫度下之薄膜結構、官能基與元素之變化。隨著溫度上升，可觀察到薄膜內部之sp2鍵結增加，氧化效應越大。再以原子力顯微鏡觀察在不同溫度下之試片表面粗糙度，結果顯示溫度越高，薄膜表面因氧化而會使粗糙度上升，但膜厚對其結果有一定的影響；由奈米壓痕試驗結果則顯示，氧化溫度越高則薄膜硬度就越低，這是因為薄膜之石墨相增多之緣故。而在刮痕試驗中則是發現CH4比例越高時，薄膜之臨界負載越大，N2比例越高則摩擦係數越低。綜合結果可看出，含氮碳膜內部N2之含量對其結構與性質有很大的影響，在氧化溫度200~400 ℃為一轉折點；薄膜厚度越厚，則抗氧化之能力越好， 即使經過高溫氧化，表面仍能保持良好的粗糙度，適合當作抗氧化之犧牲層。|
Carbon nitride films (CNx films) were deposited on WC-Co substrates by radio frequency plasma enhanced chemical vapor deposition (RF-PECVD) using a CH4/N2 mixture. A 100 nm amorphous silicon interlayer was coated by physical vapor deposition (PVD). The CNx thin films were prepared by various pressures and ratios of CH4 and N2. According to the measurement of α-stepper, the deposition rate increased under a higher working pressure. The microstructures, morphologies, and composition of the CNx films were analyzed by means of atomic force microscopy (AFM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), Fourier transformation infred spectroscopy (FTIR), and electron probe micro-analyer (EPMA). The mechanical properties of CNx films were examined by nano-indentation and nano-scrath test. As the temperature promoted, the sp2 content in the CNx films increased. The oxidation and surface roughness were also increased. CNx film’s thickness was found to be an important factor. Furthermore, from the results of nano-indentation system, the hardness decreased due to the richer graphite of CNx films as the temperature increased. The critical load increased with CH4 content, while the friction coefficient decreased with the increased nitrogen content. As a summary, the microstructure of CNx films were affected by the content of nitrogen. During 200 ℃ and 400 ℃, the structure changed suddenly. The anti-oxidation capability and surface roughness increased with the film’s thickness. CNx films can be considered as kind of an anti-oxidation layer.
|Appears in Collections:||[機械與機電工程學系] 博碩士論文|
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