Bonding mechanism between alumina and niobium

Morozümi, Shotaro; Kikuchi, Masae; Nishino, Tatsuya

doi:10.1007/bf00542374

Cited by 91 publications

(33 citation statements)

References 3 publications

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“…The copper-oxygen phase 8 Morozumi et al [27] report ≈50% bonded area after 1 h, 8.8 MPa, hv bonding at 1600°C. Turwitt et al [37] report that after a 2 h, 10 MPa hv bonding cycle at 1700°C, ≈10-20% of the interface remains unbonded, suggesting that porosity removal is slow even at substantially higher temperature.…”

Section: Brazing Using Copper-cuprous Oxide Eutectic and Joint Propermentioning

confidence: 99%

“…Generally, for conventional high vacuum (hv; ≈10 -3 Pa) diffusion bonding, studies have focussed on the temperature range 1500-1950°C, with bonding times of several hours, and a bonding load typically of the order of 10 MPa [27][28][29][30][31]. Bonding temperature reductions of up to 500°C relative to hv bonding can be achieved by the use of ultrahigh vacuum (uhv; ≈10 -8 Pa) conditions coupled with sputter cleaning of the bonding surfaces [32].…”

Section: Diffusion Bonding Conditions and Joint Propertiesmentioning

confidence: 99%

“…Bonds involving polycrystals typically undergo interfacial failure, and exhibit either lower fracture energies [37], or fracture energies nearer to the lower bicrystal values [36]. A limited number of strength measurements indicate that joints processed at 1600°C under hv conditions fail at stresses of the order of 100-150 MPa [27,29].…”

Section: Diffusion Bonding Conditions and Joint Propertiesmentioning

confidence: 99%

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Joining of alumina via copper/niobium/copper interlayers

et al. 2000

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Alumina has been joined at 1150°C and 1400°C using multilayer copper/niobium/copper interlayers. Four-point bend strengths are sensitive to processing temperature, bonding pressure, and furnace environment (ambient oxygen partial pressure). Under optimum conditions, joints with reproducibly high room temperature strengths (≈240 ± 20 MPa) can be produced; most failures occur within the ceramic. Joints made with sapphire show that during bonding an initially continuous copper film undergoes a morphological instability, resulting in the formation of isolated copper-rich droplets/particles at the sapphire/interlayer interface, and extensive regions of direct bonding between sapphire and niobium. For optimized alumina bonds, bend tests at 800°C-1100°C indicate significant strength is retained; even at the highest test temperature, ceramic failure is observed. Postbonding anneals at 1000°C in vacuum or in gettered argon were used to assess joint stability and to probe the effect of ambient oxygen partial pressure on joint characteristics. Annealing in vacuum for up to 200 h causes no significant decrease in room temperature bend strength or change in fracture path. With increasing anneal time in a lower oxygen partial pressure environment, the fracture strength decreases only slightly, but the fracture path shifts from the ceramic to the interface. Cu/Nb/Cu Interlayers R. A. Marks et al. Joining of Alumina via

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Section: Brazing Using Copper-cuprous Oxide Eutectic and Joint Propermentioning

confidence: 99%

Section: Diffusion Bonding Conditions and Joint Propertiesmentioning

confidence: 99%

Section: Diffusion Bonding Conditions and Joint Propertiesmentioning

confidence: 99%

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Joining of alumina via copper/niobium/copper interlayers

et al. 2000

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“…Joints between polycrystalline niobium and polycrystalline alumina typically exhibited either lower fracture energies [34] or fracture energies nearer to the lower bicrystal values [55]. A limited number of strength measurements indicated that joints processed at 1600°C under hv conditions failed at tensile stresses of the order of 100-150 MPa [28,32].…”

Section: Alumina/niobium Diffusion Bondingmentioning

confidence: 99%

“…Generally, for conventional high-vacuum (hv; ≈10 -3 Pa) diffusion bonding, bonding temperatures were 1500-1950°C, bonding times were typically several hours, and the applied load was generally of the order of 10 MPa [28,32,36,37,54]. The use of ultrahigh-vacuum (uhv; ≈10 -8 Pa)…”

Section: Alumina/niobium Diffusion Bondingmentioning

confidence: 99%

Liquid‐Film‐Assisted Formation of Alumina/Niobium Interfaces

Sugar

McKeown

Marks

et al. 2002

Journal of the American Ceramic Society

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Alumina has been joined at 1400°C using niobium-based interlayers. Two different joining approaches were compared: solid-state diffusion bonding using a niobium foil as an interlayer, and liquid-film assisted bonding using a multilayer copper/niobium/copper interlayer. In both cases, a 127-µm thick niobium foil was used; ≈1.4-µm or ≈3-µm thick copper films flanked the niobium. Room-temperature four-point bend tests showed that the introduction of a copper film had a significant beneficial effect on the average strength and the strength distribution. Experiments using sapphire substrates indicated that during bonding the initially continuous copper film evolved into isolated copper-rich droplets/particles at the sapphire/interlayer interface, and extensive regions of direct bonding between sapphire and niobium. Film breakup appeared to initiate at either niobium grain boundary ridges, or at asperities or irregularities on the niobium surface that caused localized contact with the sapphire.

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