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High vacuum active brazing of cBN with improved composite filler: Microstructure, interfaces and performance evaluation
Simhan D.R.,
Published in Elsevier
Volume: 183
In this work, ceramic reinforcement of soft Ag–Cu–Ti filler alloy has been attempted to produce a superior filler alloy to braze cBN to steel in high vacuum conditions without compromising wettability and joint strength. 2 and 5 wt% of micro-alumina (μAl2O3) particles of average particle size (APS) 10 μm were added to Ti-activated (2 wt%) eutectic (72Ag28Cu) filler alloy as reinforcements for brazing Cubic Boron Nitride (cBN) particles (APS: 427 μm) to steel substrate. The alloy-matrix wetted μAl2O3 particles appreciably. Cu3Ti3O phase formed (confirmed through TEM/SAED-pattern analyses) and grew surrounding the μAl2O3 particles with a very thin interlayer of γ-TiO. Nano-hardness of Cu3Ti3O was measured to be 17.6±2.42 GPa. Cu3Ti3O together with μAl2O3 particles resulted in substantially enhanced (63–76%) abrasion-resistance characteristics of the primary alloy. 5 wt% addition of μAl2O3 to Ag–Cu–2Ti alloy displayed superior performance to 2 wt% addition. However, with higher proportion (5 wt%), wettability of the reinforced filler on cBN part got slightly impaired. Few micro-voids also surfaced on cBN-encapsulating bonding layer. Considering joint strength and wettability, 2 wt% of μAl2O3 is recommended to produce brazed cBN tools for high-impact load applications. © 2020 Elsevier Ltd
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PublisherData powered by TypesetElsevier
Open AccessNo