MECHANICAL-PROPERTIES OF JOINED SILICON-NITRIDE

A technique is described to join Si//3N//4 ceramics using oxide glasses. The technique involves a glazing step, followed by a pressureless reaction treatment of 30 to 60 min at 1575 degree to 1650 degree C. Reactions between the glasses and Si//3N//4 are reported. Important events are dissolution of Si//3N//4 and the growth of Si//2N//2O crystals into the joint. The strength of joined bars depends on joint thickness. Two strength regimes are identified, and two corresponding fracture mechanisms are described.