原位形成氧氮玻璃中间层连接Si_3N_4陶瓷

Joining of Si_3N_4 Ceramics with In-situ Formed Oxynitride Glass Interlayer

用Si3N4–Al2O3–Y2O3–SiO2混合粉制备用于连接氮化硅陶瓷的焊料,原位形成以氧氮玻璃为中间层的氮化硅陶瓷接头。研究了连接过程中温度、压力及气氛对陶瓷接头微观组织及性能的影响。结果表明:在0.1MPa氩气条件下,接头内含有一定量气孔,氮化硅母材有少量分解;氮气气氛、0.1 MPa条件下可保证陶瓷母材稳定、接头致密,在氧氮玻璃中间层均匀分布有β-SiAlON陶瓷相;当氮气气压增大到0.5 MPa时,陶瓷接头无法实现有效连接。在较低温度下,当连接压力由0.6 MPa增大到1.5 MPa时,接头弯曲强度提高;升高温度,接头强度出现峰值,在1 550℃时达到最高,连接压力对接头的影响减小;继续增大压力将使液相焊料流出,甚至母材自身发生变形。

The Si3N4-AI203-Y203-SiO2 powder mixture was used to join Si3N4 to itself by in-situ formed oxynitride glass interlayer. Effects of temperature, pressure and atmosphere on bonding strength and microstructure of joints were investigated. Under 0.1 MPa argon, a few holes can be found in the joint and slight decomposition of Si3N4 matrix occurred. Under 0.1 MPa nitrogen, the stability of Si3N4 matrix can be preserved, and no pores appear in the joint. Amount offl-sialon phases can be observed, which distribute uniformly in the oxynitride glass interlayer. While under 0.5 MPa nitrogen, Si3N4 ceramics cannot be joined. The influence of bonding pressure on joints is bounded by joining temperature. When temperature is low, the bonding strength of joints can be improved with the increase of pressure from 0.6 to 1.5 MPa. When increasing temperature, the strength presents peak value at 1 550 ℃. Moreover, the influence of pressure on joint is weakened. At higher joining temperature, liquid solder is ready to flow out of the seam under higher pressure, and ceramic matrix also tends to deform.