Infrared brazing of Ti-6Al-4V and 17-4PH S.S. or Al2O3 using Ag-based braze alloys
Date Issued
2005
Date
2005
Author(s)
Huang, Chun-Shien
DOI
zh-TW
Abstract
本研究利用紅外線快速加熱的特性，研究Ag-Cu-Ti-Zr活性硬銲填料與99.5wt.% Al2O3與95wt.% Al2O3基材間的動態潤濕角以及顯微組織之變化。實驗結果得知Ag-Cu-6Ti-6Zr(wt.%)的填料比Ag-Cu-1.5Ti-1.5Zr(wt.%)者有較佳的潤濕性，此因後者易於氧化鋁表面產生Zr的氧化物。利用Ambrose所提出的預測方程式，並將特性時間τ取一適當的修正係數R，即為τ×R，實驗結果得知潤濕接觸角與時間之變化關係再現性優良。由界面顯微組織之觀察可知，Ag-Cu-6Ti-6Zr與Al2O3界面處形成Ti3.3Cu2.7O反應層，Ag-Cu-1.5Ti-1.5Zr與Al2O3界面處則形成ZrO2反應層。本研究並利用銀基填料BAg-8來硬銲接合Ti-6Al-4V與17-4PH不鏽鋼。接合前先對17-4PH不鏽鋼進行表面鍍膜，以作為擴散阻隔層，來阻擋填料與基材間相互擴散以避免硬脆之介金屬形成，並能得最佳之剪力強度。實驗結果可知，於17-4PH不鏽鋼表面化學鍍鎳有較佳的剪力強度，比較化學鍍鎳與電鍍鉻於17-4PH不鏽鋼上兩者的接合界面顯微組織，前者所生成的脆性Ti-Cu相較少，而變為TiNiCu與NiPTi兩相。在17-4PH不鏽鋼表面化學鍍鎳與電鍍鉻中，皆沒有發現TiFe相的存在。在硬銲溫度為800℃與850℃時，破斷發生在Ti-6Al-4V與填料之間的Ti-Cu相。
Dynamic wetting angles and microstructures of Ag-Cu-Ti-Zr active filler alloys on 99.5wt.% and 95wt.% Al2O3 substrates using infrared heating has been performed in the study. Experimental results show that Ag-Cu-6Ti-6Zr (wt.%) has better wettability than Ag-Cu-1.5Ti-1.5Zr (wt.%) due to Zr oxidation of the latter filler on Al2O3 substrate. The relationship between the wetting angle and time can be fitted well by the equation proposed by Ambrose et al. in which the characteristic time τis modified by τ×R, where R is a correction constant. Microstructural observations show that the interface between Ag-Cu-6Ti-6Zr and Al2O3 forms Ti3.3Cu2.7O layer. In contrast, the interface of Ag-Cu-1.5Ti-1.5Zr and Al2O3 forms ZrO2 layer. In this study, the joining of Ti-6Al-4V and 17-4 PH S.S. using the BAg-8 filler alloy is also performed. A diffusion barrier coated on the 17-4 PH S.S. is introduced prior to infrared brazing. The aim of introducing the diffusion barrier(s) is to prevent interdiffusion between two dissimilar alloys from forming intermetallics, so better bonding strength can be expected. Experimental results show that the best shear strength can be obtained from electroless-plating the Ni film on the 17-4PH S.S. Compared with the going of electroless-plating Ni film on 17-4PH S.S. and that of electroplating Cr film on 17-4PH S.S., the former has less Ti-Cu intermetallics and replaced by TiNiCu and NiPTi phases in the infrared brazed joint. Both joints do not have the interfacial TiFe compound and the fractures occur at the Ti-Cu intermetallics in between Ti-6Al-4V and filler for the joints brazed at 800℃ and 850℃.
Subjects
紅外線硬銲接合
Ag-Cu共晶活性硬銲填料
動態潤濕
擴散阻隔層Cr及Ni層
Infrared brazing
Ag-Cu active brazing fillers
Dynamic wetting
Diffusion barriers
Type
thesis
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