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研究生: 王玠龍
Jie-Long Wang
論文名稱: 常壓電漿噴射束於沃斯田體系不鏽鋼電漿輔助氮化之研究
Plasma-Assisted Nitriding of Austenitic Stainless Steel by Atmospheric Pressure Plasma Jet
指導教授: 郭俞麟
Yu-Lin Kuo
口試委員: 邱六合
Liu-ho Chiu
張銀祐
Yin-Yu Chang
林長華
Chang-Hua Lin
學位類別: 碩士
Master
系所名稱: 工程學院 - 機械工程系
Department of Mechanical Engineering
論文出版年: 2020
畢業學年度: 108
語文別: 中文
論文頁數: 137
中文關鍵詞: 常壓電漿噴射束電漿氮化快速氮化AISI 304不鏽鋼氮化沃斯田體系不銹鋼氮化
外文關鍵詞: Atmospheric pressure plasma jet, Plasma Nitriding, AISI 304 stainless steel nitriding, Austenitic stainless steel nitriding, Rapid nitriding
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摘要
AISI 304 不鏽鋼目前廣泛運用於各種領域中,包括汽車、食品、醫療器具及民生用具等。儘管不鏽鋼因著表面之氧化鉻而有著良好的抗腐蝕性,但其表面硬度並不高,因此需要經過硬化處理。表面滲氮處理為化學表面硬化技術之領域,藉由表面滲入氮原子而改變材料之機械性質,不僅提升硬度、磨耗及抗衝擊性能,更能增加材料於高負載、惡劣環境下使用之壽命。本實驗利用常壓電漿噴射束針對AISI 304不鏽鋼進行表面滲氮處理,以便獲得良好硬度之表面。相較於傳統電漿滲氮製程,常壓電漿滲氮大幅降低氮化過程所耗費之時間,縮短整道製程的複雜度,同時具備綠色製程之環保特性。
本實驗利用氮氣、氫氣混合氣作為工作氣體,並且固定電漿之瓦數、頻率、距離等條件,僅僅改變處理時間為3、5、7、9、11分鐘,用以研究不同時間條件下所獲得的相對應研究結果。本實驗利用維克氏硬度計測量表面及剖面之硬度,並且藉由X光繞射儀器檢測氮化後之試片成份。隨後利用OES光譜儀搜集電漿於氮化過程中所產出之物種及自由基,再以場發射掃描電子顯微鏡(FE-SEM)及光學顯微鏡(OM)觀察表面形貌及橫截面之組織結構,並利用EDS-Line scan及Mapping針對剖面進行掃描,以便觀察其中之組成元素,後續利用電化學分析儀探討經氮化處理後之抗腐蝕性能。由分析結果可得知,AISI 304不鏽鋼經過常壓電漿氮化處理後之表面硬度數值成功提升,由原本192 HV0.1之原始硬度於經過3至11 min之常壓電漿處理後分別提升至937 HV0.1、972 HV0.1、1156 HV0.1、1192 HV0.1與1195 HV0.1,經由觀察其剖面金相組織可得知其深度會隨著處理時間拉長而增加。另於XRD分析中可觀測到γN、Fe4N、Fe3N、CrN、α等峰值之生成,但於抗腐蝕性能則因著CrN之析出而導致整體抗蝕性下降。從OES光譜中,我們推測常壓電漿氮化機制主要還是以NH基為成功氮化關鍵因素,因此由研究之結果可得知常壓電漿可成功針對沃斯田體系不鏽鋼進行氮化處理。


AISI 304 Stainless Steel is widely used both industrially and non-industrially. Although composed of highly protective chromium oxide and thus possessing high corrosion resistance, Austenitic type stainless steel lacks surface hardness and must therefore be nitrided. The nitriding treatment could significantly increase not only surface hardness but also impact resistance, which improving the durability of service life when used in harsh environments or under conditions of harsh resistance. In this research, we proposed using the heat treatment process afforded by an Atmospheric Pressure Plasma Jet (APPJ) to modify on AISI 304 Stainless Steel to make it harder. In comparison to the conventional nitriding process, this process simultaneously minimizes our processing time while maximizing overall production line efficiency. The N2/H2 is utilized as a working gas in our experiment. With respect to parameters, there is but variable processing time (3/5/7/9/11 minutes), which are used to investigate the relationship between different processing times and corresponding results. Subsequently, these treated samples are analyzed with various instruments.
We utilize Vickers hardness tester to measure the surface hardening and Cross-section hardness. The X-ray Diffractometer (XRD) was used to observe the crystalline structure on the treated sample surface. The plasma species and radicals generated by N2/H2 working gases in an APPJ system are detected by using Optical Emission Spectroscopy (OES). Cross-section morphologies and constituent elements of nitriding layers are observed by Field Emission Scanning Electron Microscopy (FE-SEM), Optical Microscope (OM), elemental mapping, and EDS line-scan. Finally, surface impact resistance is detected using the Dynamic Fatigue Testing Machine.
The results of our research indicate that the surface hardness of AISI Stainless Steel was successfully changed into higher value. As such, the depth of the nitriding layer rose gradually with the increasing time; nevertheless, the corrosion resistance decreased significantly due to the formation of the CrN compound, which precipitated under a high processing temperature. We found that γN, Fe4N, Fe3N, CrN, α generated from the treated sample. From OES observation, we conclude that NH radical plays the definitive role in both controlling the hardening mechanism and in determining the formation of the nitriding layer.

目錄 第一章 緒論 1 1.1 前言 1 1.2 研究背景與目的 2 第二章 文獻回顧 3 2.1 AISI 304不鏽鋼 3 2.1.1 AISI不鏽鋼基本介紹 3 2.1.2 合金元素於鋼材之影響 5 2.2 表面硬化處理 8 2.2.1 化學表面硬化技術 9 2.2.2 物理表面硬化技術 10 2.3 滲氮處理 12 2.3.1 氮化法介紹 12 2.3.2 滲氮前處理 13 2.3.3 合金元素對滲氮之影響 15 2.3.4 氮化層之組織與性質 18 2.3.5 滲氮機制 21 2.4 電漿介紹 25 2.4.1 電漿基本介紹 25 2.4.2 電漿原理及機制 26 2.4.3 熱平衡、非熱平衡電漿 29 2.4.4 電漿之生成分類 31 2.4.5 崩潰電壓 34 2.4.6 常壓電漿放電方式 35 2.4.7 常壓電漿之應用 39 第三章 實驗流程與設備 46 3.1 實驗設計 46 3.2 實驗材料 48 3.3 實驗步驟 49 3.3.1 不鏽鋼滲氮前處理 49 3.3.2 常壓電漿噴射束滲氮處理流程 49 3.4 實驗設備 51 3.4.1 常壓電漿噴射束(APPJ)原理介紹 51 3.5 材料分析儀器 53 3.5.1 光學放射光譜儀(OES) 53 3.5.2 維克氏硬度機(Vickers Hardness Test) 55 3.5.3 X光繞射儀(XRD) 56 3.5.4 場發射掃描式電子顯微鏡(FE-SEM) 58 3.5.5 電化學測試(Electrochemical Test) 60 3.5.6 光學顯微鏡(OM) 62 3.5.7 動態衝擊疲勞試驗機(Cyclic Loading Device) 63 第四章 結果與討論 64 4.1 溫度分析 64 4.2 光學放射光譜儀分析 66 4.3 表面硬度分析 68 4.4 剖面硬度分析 72 4.5 EDS line scan分析 75 4.6 Mapping分析 79 4.7 X光繞射分析 85 4.8 光學顯微鏡(OM) 90 4.9 FE-SEM 93 4.10 EDS 分析 97 4.11 電化學動電位極化曲線分析 99 4.12 動態衝擊疲勞試驗分析 101 4.13 常壓電漿滲氮機制探討 108 第五章 結論 111 第六章 未來展望 113 第七章 參考文獻 114

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