Characterization of alumina–alumina/graphite/monel superalloy brazed joints

Ghosh, Sumana; Chakraborty, Riya; Dandapat, Nandadulal; Pal, Kalyan Sundar; Datta, Someswar; Basu, Debabrata

doi:10.1016/j.ceramint.2011.07.054

Cited by 25 publications

(14 citation statements)

References 38 publications

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“…This was in good agreement with our earlier reported data and other published data. 21,22,26) SEM images of the conventional and microwave-assisted brazed joints of alumina ceramics (Fig. 3) showed that the interfacial regions were devoid of any crack or other defects.…”

Section: Resultsmentioning

confidence: 99%

“…According to our earlier paper 22) heating and cooling rate was maintained. The total processing time for the conventional brazing operation was ³9 h. The microwave-assisted joining was conducted in a multimode microwave furnace with a magnetron having frequency of 2.45 GHz and maximum output power in the range of 0.3 to 3 kW (Enerzi Microwave Systems Pvt.…”

Section: Methodsmentioning

confidence: 99%

“…We have already carried out investigations on the alumina-alumina, alumina-graphite and alumina monel super alloy conventionally brazed joints for electron tube applications. 21,22) Joining of alumina ceramics using TICUSIL filler alloy has been widely investigated. 2325) In the present work, microwave hybrid heating (MHH) principle was utilized to produce reliable joints of alumina ceramics for suitable use in electron tube and rapid cycle proton synchrotron machine.…”

Section: Introductionmentioning

confidence: 99%

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Fabrication of Reliable Joints of Alumina Ceramics by Microwave-Assisted Reactive Brazing Technique

et al. 2016

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Microwave-assisted reactive brazing technique was utilized for joining of alumina ceramics at 950°C and 1050°C for 20 min in argon atmosphere using .5Ti in mass%) paste as the braze alloy. Conventional heating technique was also employed for comparison purpose only. The microwave and conventionally brazed joints were characterized by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray analysis and Vickers microhardness measurement. X-ray diffraction data showed that the Ti-based compounds were formed at the substrate-filler alloy interfaces of the microwave and conventionally brazed joints. Scanning electron microscopy exhibited the formation of thicker reaction region in the case of joints microwave brazed at higher temperature. Energy dispersive X-ray analysis determined the elemental compositions across the joint cross-section. Vickers microhardness measurements indicated more reliable performance of the joints microwave brazed at lower temperature. Hermiticity of the microwave and conventionally brazed joints was evaluated by Helium leak test and found to be acceptable for actual applications.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Fabrication of Reliable Joints of Alumina Ceramics by Microwave-Assisted Reactive Brazing Technique

et al. 2016

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“…Ghosh et al . (2012) 61 – 99.99 % pure alumina powder sintered at 1600 °C for 2.0 hours. Lin et al .…”

Section: Introductionmentioning

confidence: 99%

Secondary Phase Interaction at Interfaces of High-Strength Brazed Joints made using Liquid Phase Sintered Alumina Ceramics and Ag-Cu-Ti Braze Alloys

Kassam

Babu

Ludford

et al. 2018

Sci Rep

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Alumina-to-alumina brazed joints were formed using 96.0 and 99.7 wt.% Al2O3 ceramics using 150 µm thick Ticusil® (68.8Ag-26.7Cu-4.7 wt.% Ti) braze preforms. Brazing was conducted in a vacuum of 1 × 10−5 mbar at 850 °C for 10 minutes. Joint strengths were evaluated using four-point bend testing and were compared to the monolithic flexural strengths of standard alumina test bars according to ASTM C1161-13. Brazed joints made using 96.0 wt.% Al2O3 consistently outperformed brazed joints made using 99.7 wt.% Al2O3, despite similarities in both the flexural strengths of the standard alumina test bars and the microstructures of brazed joints. Secondary phase interaction led to the formation of Ti5Si3 reaction products at locations where the triple pocket grain boundaries of the 96.0 wt.% Al2O3 surface intersected the Ti-rich reaction layers. It is proposed that due to this interaction, brazed joints made using 96.0 wt.% Al2O3, which were relatively cost-effective to produce, achieved higher strengths than brazed joints made using 99.7 wt.% Al2O3.

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“…[1][2][3][4] It is difficult to manufacture alumina into complex-shaped products due to the high hardness and brittleness of the material. [6][7][8][9][10][11] In addition, the application of these methods is limited due to the necessary vacuum or inert gas atmosphere during processing and the high cost and low efficiency of such complicated processes. Brazing and diffusion bonding can be used to join alumina ceramics, but the joints suffer from poor high-temperature strength, poor toughness, and high residual stress.…”

Section: Introductionmentioning

confidence: 99%

Epitaxial growth of aluminum borate whiskers and simultaneous joining of alumina ceramics via a sol–gel method

et al. 2016

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Aluminum borate whiskers were epitaxially grown on alumina by a sol-gel method. The morphology of the whiskers was investigated via scanning electron microscopy, X-ray diffraction and transmission electron microscopy. As the holding time and growth temperature increased, the length of the whiskers first increased and then decreased. The whiskers (Al 4 B 2 O 9 and Al 18 B 4 O 33 ) were 5-20 mm in length and hundreds of nanometres in diameter under all growth parameters. In addition, the whiskers synthesized by the sol-gel method were successfully used to join alumina in air. SEM images showed that the whiskers grew across the seam, and the width of the joint was consistently less than 10 mm. The shear test results showed that the highest strength of the joints reached 84.5 MPa at a bonding temperature of 950 C maintained for 8 h. Fracturing consistently occurred within the network structure in the seam.

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Characterization of alumina–alumina/graphite/monel superalloy brazed joints

Cited by 25 publications

References 38 publications

Fabrication of Reliable Joints of Alumina Ceramics by Microwave-Assisted Reactive Brazing Technique

Fabrication of Reliable Joints of Alumina Ceramics by Microwave-Assisted Reactive Brazing Technique

Secondary Phase Interaction at Interfaces of High-Strength Brazed Joints made using Liquid Phase Sintered Alumina Ceramics and Ag-Cu-Ti Braze Alloys

Epitaxial growth of aluminum borate whiskers and simultaneous joining of alumina ceramics via a sol–gel method

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