Wetting and Interactions Between Selected Ceramics and Ni-Base Braze Alloys
Wetting tests were performed with two commercial Ni-base braze alloys on a selection of ceramic materials in vacuum between 1000 and 1150°C. The two alloys were Ni-5Si-3B and Ni-7Cr-5Si-3Fe-3B(wt%). The ceramic substrates included Al2O3, Si3N4, TiC/TiN coated Si3N4, SiC, a SiC/SiC CVI composite and a TiC/TiN coated SiC/SiC CVI composite. In one experiment a thin foil of Ti was placed between the braze alloy and the ceramic in an attempt to promote wetting. With Al2O3, Si3N4 and TiC/TiN coated Si3N4 there were no observable reactions between braze and substrate, the wetting was poor (contact angles Θ ≥ 110°) and the braze drops detached themselves after solidifying. With a thin foil of Ti between the braze alloy and the Si3N4 ceramic a restricted reaction was noticed and wetting occurred (Θ≈70°). The braze detached itself but in this case this was due to fracture through a brittle reaction product. The bulk SiC substrate exhibited a strong chemical reaction with the braze. The SiC/SiC composite exhibited “good” wetting but this could be explained by the open porosity of the material and a penetration of the braze alloy. On the two SiC/SiC materials the braze alloy adhered to the ceramic and reaction could be observed. Wetting tests were also performed on the superalloys, Hastelloy X and Incoloy 909; both exhibited satisfactory wetting behaviour.
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- 1.Knotek, O., Lugscheider, E., Brazing Filler Metals Based on Reacting Ni-Cr-B-Si Alloys. Welding Journal, 1976, 10, 314s–318sGoogle Scholar
- 2.Nicholas, M.G., Peteves, S.D., this conferenceGoogle Scholar
- 4.Weitzer, F., Schuster, J.C., Phase Diagrams of the Ternary Systems Mn, Fe, Co, Ni-Si-N, J. Solid State Chemistry, 1978, 178–184Google Scholar
- 5.Rühle, M., Mader, W., Structure and Chemistry of Metal/Ceramic Interfaces, In Designing Interfaces for Technological Applications, ed. S.D. Peteves, Elsevier Applied Science, London, 1986, pp 145–195Google Scholar