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直流电热冲击辅助多组分氧化物钎焊SiC陶瓷的工艺及性能

Process and properties of SiC brazing through multicomponent oxide assisted by electrothermal shock

  • 摘要: 开发了一种直流电热冲击辅助高温钎焊新技术,成功实现了18.77Gd2O3−4.83Y2O3−28.22TiO2−8.75ZrO2−39.43Al2O3多组分氧化物钎料与SiC陶瓷母材之间的钎焊连接. 加热元件采用碳纤维编织体,在20 A直流电流及800 W截断功率下,实现了最佳剪切强度为136.27 MPa的SiC钎焊接头. 多组分氧化物钎料中Al2O3及TiO2组分对实现良好的SiC陶瓷钎焊接头至关重要,其中TiO2组分与SiC在高温下发生反应从而在界面处生成厚度约为10 μm的富Ti界面反应层,Al2O3相向母材中渗入而形成的枝状通道起到钉扎效果,有利于提升钎焊接头整体强度. 热输入过大时,SiC母材严重分解,大量C元素向钎缝区扩散,导致钎缝区出现明显裂纹缺陷,剪切强度降低至约60 MPa,断裂完全发生于钎缝区.

     

    Abstract: An electrothermal shock-assisted high-temperature brazing technology was proposed in this work, which successfully achieved the joining of 18.77Gd2O3-4.83Y2O3-28.22TiO2-8.75ZrO2-39.43Al2O3 multicomponent oxide filler and SiC ceramics. The SiC brazed joint with an optimal shear strength of 136.27 MPa was achieved under 20 A DC current and 800 W cut-off power by using carbon fiber as the heating element. The Al2O3 and TiO2 components in the multi-component oxide filler metal were very important to achieve a good SiC ceramic brazing joint. TiO2 reacted with SiC at high temperature to generate a Ti-rich interfacial reaction layer with a thickness of ~10 μm at the interface, and Al2O3 penetrated into the base metal to form a pinning effect, which was beneficial to improve the brazed joint strength. However, when the heat input was too large, the SiC base metal would decompose seriously, and a large amount of C element would diffuse to the brazing seam, resulting in obvious crack defects. The shear strength would be reduced to ~60 MPa, and the fracture completely occurred in the brazing seam.

     

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