| Popis: |
This study provides effects of bonding temperature conditions on practical strength in ceramic to metal joint system made by two stages bonding process. Ceramic to metal joint system is required to reduce the residual stress near the edge of the interface and to improve bonding strength. The two stages bonding process, which was proposed in PVP2015-45822, can be a useful method to prevent the residual stress from increasing. This process consists of two stages, the first bonding process defined as a ceramic is bonded to thin metal layer at high temperature and the secondary process defined as a thick metal is bonded to the thin metal layer of the joint at lower temperature. It is necessary to provide effects of thickness of thin metal layer on the practical bonding strength in various combinations of the first and the secondary bonding temperature conditions. Past experimental results showed the practical bonding strength would be dominated by the residual stress near the edge of the interface between the thin metal layer and the ceramic. The residual stress can be associated with the first and/or the secondary bonding temperature conditions. Setting the optimum metal thickness improves the bonding strength independent of the bonding temperature conditions in the limited conditions. This paper provided dependence of the optimum metal layer thickness on the first and the secondary bonding temperature conditions was clarified experimentally. It also found effective metal thickness, which is capable of strengthening the siliconnitride to nickel joint system, in the combination of the first bonding temperature ranged over from 880°C to 980°C and the secondary bonding temperature ranged over from 600°C to 700°C. It appeared the first bonding temperature and the secondary one are set at the higher, the optimum metal thickness becomes smaller. The result showed that decreasing metal thickness possesses similar effect to decreasing bonding temperature for reducing the thermal residual stress. Reducing the residual stress is capable of strengthening the part of the edge of the interface on the ceramic side. Setting the metal layer thinner should be applied for producing the high strength ceramic to metal joint system. The two stages bonding process can contribute to achieve the high strength bonded dissimilar materials by setting the optimum thin metal thickness. |
