Diffusion Bonding of Si3N4/TiN and Si3N4/TiB2 Composites to Incology 909
Reduction of thermo-mechanical stresses in ideal-elastic diffusion joints between silicon nitride and superalloys can be accomplished by ceramic joint pieces of graded compositions made of Si3N4 and a supplementary ceramic phase.
In this work, TiN and TiB2 were chosen as supplementary ceramic phases in particulate composites with Si3N4 due to their suitable properties and the availability of such materials. Diffusion bonding of the composites to Incoloy ® 909 was performed by Hot Isostatic Pressing (HIP) at 1200 K (927°C) and 200 MPa for 4 h. The influences of the TiN phase or TiB2 phase on diffusion reactions between the Si3N4 phase and the superalloy constituents (Fe, Ni, Co, Nb, Ti, Si) were compared by examination with TEM/STEM/EDS.
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