1993 年 11 巻 4 号 p. 525-530
Formation of defects such as porous zone and crack in the reaction layer of Si3N4 to molybdenum joints was investigated using pressureless sintered (PLS-) and hot-pressed (HP-) Si3N4 with Cu-5%Cr, Cu-1%Nb and Cu-3%V insert metals.The obvious porous zone occurred in the reaction layer of PLS-Si3N4 to molybdenum joints when the reaction layer was relatively thick, while the porous zone did not occur in the reaction layer of HP-Si3N4 to molybdenum joints. The volume change with interfacial reaction between Si3N4 and the reaction layer was estimated from the analytical results of silicon content in the reaction layers. The volume after reaction was seemed to decrease to that before reaction in case that any insert metals were employed during bonding of PLS- and HP-Si3N4 to molybdenum. It was deduced that the porosity in Si3N4 substrate and the volume change before and after interfacial reaction were the important causes of the porous zone formation.
The cracking in the reaction layer was appeared to be affected basically by the thermal stress generated during cooling process, and also to be promoted by the porous zone in the reaction layer which could be the stress concentration sources.