- 學位論文
中空陰極放電離子覆膜製備之摻氮氧化鋯薄膜其相變化與防蝕性研究
The Phase Transition and Corrosion Resistance of N-doped ZrO2 Thin Films Deposited by HCD-IP
摘要
本論文利用中空陰極放電離子覆膜系統沉積摻氮之氧化鋯薄膜，並分別鍍著於Si基材及AISI 304不鏽鋼基材。鍍膜過程中固定氧氣流量在10 sccm，並控制氮氣流量從0 sccm增加至12 sccm以產生不同含氮量及結晶相比例的摻氮之氧化鋯薄膜。利用X光光電子能譜以及X光繞射圖確認薄膜中成分以及結晶相比例。結果顯示，隨著氧化鋯薄膜中含氮量增加，X光繞射圖顯示m-ZrO2逐漸減少，而c-ZrO2隨之增加；當氧化鋯薄膜中含氮量高於固溶限時，將會產生ZrN，其中氮的固溶限在不鏽鋼基材與Si基材分別是8.8 at%與8.3 at%。試片經真空熱處理後，發現鍍著於不同基材上摻氮之氧化鋯薄膜產生不同的相變化。在含氮量較高的不鏽鋼系列試片中發現，c-ZrO2發生相分離並產生較多ZrN，但在Si基材試片中的c-ZrO2卻直接轉變為Zr2ON2。深入研究基材對於相變化的影響後，發現摻入的氮扮演重要角色。不同相變化也連帶影響到試片顏色以及成分的均勻性。對於鍍著摻氮氧化鋯薄膜之不鏽鋼試片，使用動態極化掃描分別在鹽水(5% NaCl)與硫酸(1N H2SO4)中測試其抗腐蝕能力，並利用鹽霧測試來檢驗鍍層對於鹽霧的耐受性。結果顯示抗腐蝕能力主要受到薄膜堆積密度以及主要結晶相的影響，同時發現摻氮之氧化鋯薄膜伴隨著適量的ZrN，有較優良的抗腐蝕能力及鹽霧耐受性。其中含有14.4 % ZrN的摻氮之氧化鋯薄膜在抗腐蝕能力上展現絕佳的熱穩定性，在熱處理前後都維持著極佳的抗腐蝕性。在腐蝕測試之後，薄膜並沒有發生脫落現象，因此中空陰極放電離子覆膜製程可以用於克服表面潤濕性障礙並顯著提升氧化鋯薄膜在不鏽鋼基材的附著性。
並列摘要
N-doped ZrO2 thin films were deposited respectively on Si (Si-series) and 304 stainless steel (SS-series) substrates using hallow cathode discharge ion-planting (HCD-IP). The objectives of the present study were to understand the effect of substrate materials on phase transition and to provide a feasible approach to manufacture N-doped ZrO2 coatings with excellent corrosion resistance and good adhesion. By maintaining oxygen flow rate at 10 sccm and adjusting nitrogen flow rate, ranging from 0 to 12 sccm, the compositions and phase ratios of the N-doped ZrO2 thin films can be controlled. With increasing nitrogen flow rate, the XRD patterns showed that the phase content of c-ZrO2 increased while that of m-ZrO2 decreased, and then ZrN phase increased. The N solubility limit in ZrO2 for the formation of ZrN was 8.8 and 8.3 at% for the as-deposited thin film on SS and Si, respectively. After annealing in vacuum, different phase transitions were found for the specimens of different substrates. At higher nitrogen content, phase separation of ZrN from c-ZrO2 occurred in the SS-series specimens, while the main phase transformed from c-ZrO2 into Zr2ON2 in the Si-series specimens. The difference in defects between SSAD and SiAD-series specimens may be derived from the substrate effect, leading to different phase transitions after annealing. The corrosion resistance of SS-series specimens was evaluated by potentiodynamic scan in both 5% NaCl and in 1N H2SO4 solutions, and salt spray test was employed to access the durability of the films. Corrosion resistance was associated with film packing density and major phases. The HCD-IP method can effectively overcome the surface wetting problem of ZrO2 on stainless steel, and hence N-doped ZrO2 coating on stainless steel possesses excellent adhesion and corrosion resistance. N-doped ZrO2 thin films containing from 14.4 % to 28.8 % ZrN were found to have better corrosion resistance than pure ZrO2 thin films.