臺灣博碩士論文加值系統

本文目的為探討多脈衝式Nd-YAG雷射輔助金屬粉末/樹脂披覆系統的效果，以數值模擬與實驗方法進行研究。數值模擬部份使用數值分析軟體FLUENT，在不同的輸送高度與時間下，計算樹脂輸出的情形，進而得到複合層高度的趨勢。在實驗部份先觀察複合層的分佈情形，接著進行單點與連續的脈衝式雷射披覆加工，並量測披覆試件的表面形貌，探討不同的送膠參數對披覆層高度的影響，最後將披覆試件進行微拉伸試驗與金相組織觀察。
實驗與數值模擬結果皆顯示，複合層的高度會隨著送膠參數改變，但須在適當的複合層高度下，才可獲得較高的披覆層高度，而經由多脈衝式雷射加工，可得到連續單點披覆組成的線披覆。由微拉伸實驗結果可發現連續披覆層的強度高於母材，而觀察金相顯微組織得知其結構與雷射燒結現象相似，且點與點之間結合效果良好。

The purpose of this thesis is to characterize the metal powder/resin cladding system with the Nd-YAG laser numerically and experimentally. In the numerical simulation, the FLUENT software was applied to simulate the flow field of the resin output from a feeder nozzle on a substrate with various outlet heights and output times.

In the experiment, the distribution of the metal powder/resin composite layer has been visualized. The multi-pulse cladding was made by the pulsed Nd-YAG laser. Furthermore the cladding specimen was verified by micro tensile test and metallurgical observation.

Both the numerical simulation and experimental results show that an optimum cladding profile could be obtained with proper selection of the composite outlet height. According to the micro tensile test, the strength of the multi-pulse cladding layer is higher than the base material. It can be found the cladding microstructure is similar to that of the conventional laser cladding but with fine bonding structure.

摘要……………………………………………………………………... I
Abstract…………………………………………………………………. II
誌謝……………………………………………………………………... III
目錄……………………………………………………………………... IV
表目錄…………………………………………………………………... VIII
圖目錄…………………………………………………………………... X
符號說明………………………………………………………………... XIII

第一章 緒論……………………………………………………………. 1
1-1研究目的………………………………………………………... 1
1-2文獻回顧………………………………………………………... 3
1-2.1連續式雷射作用預置複合層之披覆製程相關研究…….. 3
1-2.2脈衝式雷射作用預置複合層之披覆製程相關研究…….. 7
1-3本文架構………………………………………………………... 12

第二章 脈衝雷射現象與製程原理……………………………………. 13
2-1雷射披覆機制…………………………………………………... 13
2-1.1雷射披覆加工參數……………………………………….. 14
2-1.2披覆品質………………………………………………….. 16
2-2 流場理論與複合材料性質…………………………………...... 18
2-2.1多相流流體力學………………………………………...... 18
2-2.1.1多相流的自由表面………………………………..... 18
2-2.1.2多相流的連續、動量和能量方程式……….……….. 19
2-2.2複合材料性質…………………………………………...... 20
2-3表面張力………………………………………………………... 22

第三章 數值模擬及分析……………………………………................. 27
3-1數值模擬軟體FLUENT分析流程……………………………... 27
3-2物理性質及模擬模型…………………………………………... 28
3-2.1物理性質………………………………………………...... 28
3-2.2複合層流動模擬假設與設計…………………………...... 30
3-3複合層流動之模擬結果………………………………………... 33
3-4結果與討論……………………………………………………... 42

第四章 實驗……………………………………………………………. 43
4-1實驗設備及流程………………………………………………... 43
4-1.1實驗設備………………………………………………...... 43
4-1.2實驗流程………………………………………………...... 47
4-2實驗參數與控制步驟…………………………………………... 48
4-3複合層成形與流動觀察………………………………………… 50
4-3.1複合層成形結果………………………………………...... 50
4-3.2複合層流動之實驗結果與數值模擬結果比較………...... 52
4-4粉末遮蔽效應…………………………………………………... 59
4-5 披覆層表面形貌量測…………………………………..…...... 60
4-5.1單點披覆………………………………………………...... 60
4-5.2連續披覆………………………………………………...... 65
4-6披覆層微拉伸實驗與斷面金相組織觀察……………………... 72
4-6.1披覆層微拉伸實驗……………………………………...... 72
4-6.2斷面金相組織觀察……………………………………...... 74
4-7 結果與討論…………………………………………………...... 76

第五章 綜合討論與建議…………………………………………......... 78
5-1綜合討論………………………………………………………... 78
5-2未來發展與相關建議…………………………………………... 81

參考文獻………………………………………………………………... 82
附錄……………………………………………………………………... 85
自述……………………………………………………………………... 88

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