【摘要】 无压烧结SiC(SSiC)陶瓷是重要的高温结构材料,连接技术是扩大其应用范围的关键技术之一。将纳米Si粉添加到聚硅氧烷(SR355)中制成连接材料,通过反应成形连接工艺连接SSiC。结果表明,纳米Si粉的加入对SR355的交联固化以及裂解和结晶化过程有一定的抑制作用,并能增加其陶瓷产率,因而可减少中间层的气孔率和收缩率,有利于连接强度的提高。纳米Si粉的最佳添加量为2%(质量分数)。连接温度对接头强度有显著影响,在纳米Si粉添加量为2%、连接压力为40 kPa、保温时间为30 min的条件下,当连接温度为1 100℃时,连接强度达到最大值64.7 MPa。微观结构研究显示,该试样中间层由C、O和Si元素组成,界面结合较好,Si和O元素在界面区域发生扩散,有利于提高连接强度。更多还原

【Abstract】 Pressureless sintered SiC(SSiC) is an important high temperature structural material,and the joining technique is one of the key techniques to extend its application.Joining of SSiC was carried out by the reaction joining process using polysiloxane SR355 with additive Si nanopowder as joining materials.The results show that the additive Si nanopowder restrains the SR355 from cross-linking,curing,pyrolyzing and crystallizing to some extent.The addition of Si nanopowder also results in the increase of the ceramic output of the SR355 after pyrolysis,which leads to the decrease of the porosity and shrinkage of the interlayer,contributing to the increase of the join strength.The maximum join strength was obtained when mass fraction of the additive Si nanopowder is 2%.The join strength is strongly affected by the joining temperature.The join strength reaches its maximum of 64.7 MPa at the joining temperature of 1 100 ℃ under the conditions that the content of the additive Si nanopowder is 2%,the joining pressure is 40 kPa and the holding time is 30 min.Microstructural study of the sample reveals that the interlayer is composed of C,O and Si,and the contact at the interfaces is basically intact.The diffusions of Si and O take place at the interfacial area in the joining process,contributing to the increase of the join strength of the joint.更多还原