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Wetting and Joining of Mullite Ceramics by Active‐Metal Braze Alloys
Author(s) -
Loehman Ronald E.,
Tomsia Antoni P.
Publication year - 1994
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1994.tb06989.x
Subject(s) - mullite , materials science , brazing , eutectic system , wetting , ceramic , sessile drop technique , metallurgy , alloy , oxide , composite material
Mullite and ZrO 2 ‐toughened mullite (ZTM) were joined with Ag─Cu eutectic braze alloys that contain Ti or Zr as active elements. Although neither the alloy compositions nor the processing conditions were optimized, four‐point bend strengths of joined bars were as high as 108 MPa. Joining reactions were studied by conducting separate sessile drop experiments with molten Ti─Ag─Cu and Zr─Ag─Cu alloys on mullite for times and temperatures that were similar those used for joining. Detailed compositional and microstructural analyses of those metal–ceramic interfaces revealed a complex reaction zone in which the oxide of the active element was a principal reaction product. Compared with the Ti‐containing alloys, those with Zr were more refractory, they were less reactive with the mullite, and the Zr did not segregate as completely to the interface during heating.