氮化硅陶瓷连接工艺及结合强度研究

STUDY ON JOINING PROCESSES AND BOND STRENGTH OF SILICON NITRIDE CERAMICS

采用由Ｙ２Ｏ３，Ａｌ２Ｏ３，ＳｉＯ２和Ｓｉ３Ｎ４粉料配制的焊料对氮化硅陶瓷进行连接试验，探讨了组分、焊接温度、压力和保温时间对结合强度的影响规律．结果表明，结合层致密化程度是影响结合强度的关键因素．随着焊料中α－Ｓｉ３Ｎ４含量的增加，结合强度先升后降．在较高的温度下纯液态玻璃焊料容易从结合层流失，而对于氮化硅－玻璃复合焊料，高温加速了α－Ｓｉ３Ｎ４向β－Ｓｉ３Ｎ４转变的动力．合适的压力可以保证焊料具有良好的流动性，随着保温时间的延长，结合层的厚度减小，这有助于结合层的致密化．用ｎ（α－Ｓｉ３Ｎ４）／ｎ（Ｙ２Ｏ３＋Ａｌ２Ｏ３）＝０．７０的焊料在Ｎ２气氛、５ＭＰａ和１６００℃保温３０ｍｉｎ的条件下连接氮化硅，所获得的最大结合强度为５５０ＭＰａ．

Pressureless sintered Si 3N 4 ceramics were joined using adhesives consisting of mixed Y 2O 3, SiO 2, Al 2O 3 and Si 3N 4 powders. The effects of joining conditions such as adhesive composition, temperature, pressure and holding time on bond strength were investigated. The results show that the bond strength depends mainly on the densification extent of the joint. The bond strength increases at first then decreases with increase of silicon nitride content in the adhesive. The liquid_forming components are reduced by the addition of α -Si 3N 4 to glass solders which restricted the amount of densification in the joint layer. The pure liquid_state glass adhesive flows out easily from the joint at higher temperature, but the kinetics of α -Si 3N 4 to β -Si 3N 4 phase transformation are accelerated for Si 3N 4-galss composite adhesives at higher temperature. Good fluidity can be assured for the adhensive under appropriate pressures. Thickness of the joint decreases with the increase of the holding time which is helpful for densification of the joint. The maximum bond strength of 550 MPa, i.e., about 80% of that of unbonded materials, is obtained at 1 600 ℃ for 30 min under an external pressure of 5 MPa in N 2 atmosphere.