STRENGTH AND MICROSTRUCTURE OF SILICON-NITRIDE CERAMICS BRAZED WITH NICKEL-CHROMIUM-SILICON ALLOYS

Joining of sintered Si3N4 was performed using a high-temperature brazi ng technique. Ni-based brazing alloys having the same Ni:Cr ratio as A WS BNi-5 (Ni . 18Cr . 19Si (at.%)) but different Si content were used as the brazing filler metals. Joining experiments were performed at 12 20 degrees C under a N-2 partial pressure of 15 Pa for different times between 5 to 15 min. The highest room-temperature four-point bend str ength of the joints was 115 MPa, whereas 220 MPa was achieved when the joints were tested at 900 degrees C. The high strength of the experim ental joints was attributed to the reduction in residual stresses and formation of a CrN reaction layer at the ceramic/filler metal interfac e.