本研究是以鎢極惰氣遮護電弧銲覆方式，將預混摻之鐵、鉬金屬粉末及碳粉末，銲覆於SC45 中碳鋼基材上。由先前實驗室的研究結果得知，高溫450℃下進行磨耗測試，其環對盤滑動摩擦係數約0.3，每百萬牛頓-米之耗損量為0.67 毫克，得到了較基材甚佳的硬度及抗磨耗性質。藉由X 光繞射、金相組織觀察、電子微探針掃瞄儀、穿透式電子顯微鏡的分析比對銲覆層凝固組織，並利用電子繞射來鑑定各相成分的分佈行為。
實驗結果顯示：經鎢極惰氣遮護電弧銲覆後之銲覆層，是以枝狀晶為主的共晶凝固組織。X 組試樣中，β-Mo2C 乃是位於未熔融鉬顆粒旁形成的樹枝狀；γ 相（分散相）是以圓柱的形狀凝固在樹枝晶中；而η-Fe3Mo3C（連續相）則是在樹枝晶內的圓柱間凝固下來。Z 組試樣中，η-Fe3Mo3C 首先凝固成枝狀晶，接著才是γ 相在枝間晶部位凝固。凝固路徑為：α + L → α + γ + L → α + γ + L+ η → γ + η。
γ 相及η-Fe3Mo3C，均為面心立方結構，呈有序排列，晶格一致性良好，且二者具有完美的晶向關係。

This research is based on “GTAW” mode, toweld the premixedferrite, molybdenum, and carbon powders on SC45 carbon steel substrate.
Learning from the previous experiments, a wear test under a high temperature of 450℃, was employed to get the Ring-disk coefficients of
sliding friction about 0.3, the depletion amounts to 0.67 mg Nm per million, that exhibited a better hardness and anti-wear property than the
substrate.
The welding layer’s solidification structure was examined by XRD,SEM, EPMA and TEM.
The experimental results revealed that in the layer welded with GTAW, primary dendritic arms are of eutectic solidification structures.
In X sample, β-Mo2C is located in the dendrite closed to the un-melted zone. We can see that γ phase (dispersed phase) with the rod shape solidified in the dendrite. And then η-Fe3Mo3C (continuous phase) solidified between the rod spacing.
In Z sample, η-Fe3Mo3C solidified as dendrite first, and then the γ phase solidified between the inter-dendrite. The solidification path is “α + L → α + γ + L → α + γ + L+ η → γ + η”.
γ phase and η-Fe3Mo3C are both FCC structures in an ordered phase, and the coherence of lattice is good, with a perfect orientation
relationship.

目錄
1.1 研究背景………………………………………………………...1
1.2 研究動機與目的………………………………………………...5
2.1 鉬對銲覆層組織和性質的影響………………………...………7
2.2 銲覆後的麻田散鐵變態對銲覆層組織和性質的影響………...8
2.3 凝固組織對銲覆層組織和性質的影響……………………….10
3.1 實驗材料及處理……………………………………….............12
3.2 氬銲銲覆處理………………………………………………….12
3.3 X 光繞射實驗…………………………………………………..13
3.4 金相實驗……………………………………………………….13
3.5 電子微探儀觀察…………………...…………………..………13
3.6 電子顯微鏡試片的製備……………………………………….14
3.7 穿透式電子顯微鏡觀察…………………...…………………..14
3.8 實驗流程圖………………………………………………….....15
4.1 X 光繞射分析………………………….…………….…………16
4.2 金相組織觀察………………………………….………………17
4.3 微結構觀察………………………………………………….....20
伍. 結論………………………………………………………………...24
陸. 參考文獻…………………………………………………………...26
柒. 表………………………………………………………...................29
捌. 圖…………………………………………………………………...32
玖. 附錄…………………………………………………………….......71
表目錄
表1 銲接方式的特性比較………………………………………......29
表2 碳化鉬的種類及堆疊方式……………………………………..29
表3 樹突之生長方向和晶體構造之關係…………………………..30
表4 各組預塗佈層含有Mo、C、Fe 重量與其莫爾百分比…………30
表5 經銲覆後各組生成成份及硬度表……………………………..30
表6 X 組中以EPMA做WDS定量所得之結果……………………31
表7 Z 組中以EPMA 做WDS定量所得之結果……………………31
圖目錄
圖1 惰氣鎢極遮護電弧銲接基本設備與電弧產生原理示意圖…..32
圖2 (a)各組在室溫與450℃下之磨耗重量損失……......................33
(b) X 組摩擦係數與時間關係………………………………...33
(c) Z 組摩擦係數與時間關係…………………………………34
(d) SKD61 熱作工具鋼摩擦係數與時間關係………………..34
圖3 Mo-C系統之二元相圖…………………………………………35
圖4 Fe-Mo 系統之二元相圖(a)MoC (b)α-Mo2C (c)β-Mo2C……...35
圖5 碳化鉬的堆疊示意圖…………………………………………..36
圖6 η-Fe3Mo3C 相的結構示意圖……..…………………………….37
圖7 就相同的成長速率而言，溫度梯度對於凝固組織的影響……38
圖8 單一相合金中，不同的凝固組織……………………….……..39
圖9 預佈塗粉末0.5mm 於試片示意圖…………………………….39
圖10 實驗流程圖………………………………………………….….40
圖11 X組X光繞射圖………………………………………………...41
圖12 Z 組X 光繞射圖………………………………………………..42
圖13 X 組俯視面在SEM下之BEI 影像…………………………….43
圖14 X 組凝固組織top view 之mapping 結果………………………46
圖15 X 組凝固組織cross-section 之mapping 結果………………….48
圖16 Z 組俯視面在SEM下之BEI 影像……………………………..52
圖17 Z 組凝固組織top view之mapping 結果………………….……55
圖18 Z 組凝固組織cross-section 之mapping 結果…………………..57
圖19 X 組經TIG 銲覆後，凝固組織的TEM照片…………..……….61
圖20 X 組經TIG 銲覆後，凝固組織的TEM照片………….….…….64
圖21 Z 組經TIG銲覆後，凝固組織的TEM照片……….….….…….66
圖22 η-Fe3Mo3C之crystal graphic………………………….………..69
圖23 X 組凝固組織示意圖…………………………………………..70
圖24 Z 組凝固組織示意圖…………………………………………..70
附錄目錄
附錄A. Fe-Mo-C 三元相圖
A-1. Isothermal section at 1273℃……………………….……………71
A-2. Isothermal section at 1000℃……………………….……………72
A-3. Isothermal section at 800℃………………………...……………73
A-4. Isopleths at constant 55 at.% Fe………………………………....74
A-5. Isopleths at constant 85 at.% Fe………………………………....75
附錄B. Fe-Mo-C 相關JCPDS Files
B-1. Mo………………………………………………………………..76
B-2. γ-Fe……………………………………………………………....77
B-3. β-Mo2C…………………………………………………………..78
B-4. η-Fe3Mo3C……………………………………………………….79
附錄C. Calibration of TEM
C-1. Calibration of JEOL 3010AEM……………………………….....80
C-2. Calibration of JEOL 200CX………………………………..........81

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