Abstract:

To address the poor wettability and insufficient interfacial activity of active components in brazing silicon nitride (Si₃N₄) ceramics to metals, we proposed replacing the traditional Ti active component with Sc. Using a modified sessile drop method, we systematically investigated the wetting behavior of Sn-xSc [x=1%, 2%, 2.5% and 3%(atomic fraction)] alloys on Si₃N₄ ceramics over the temperature range of 700—800℃. The experimental findings demonstrated that the incorporation of the active element Sc substantially decreased the contact angle of the Sn-xSc/Si₃N₄ system. The wetting performance exhibited a pronounced dependence on both temperature and Sc concentration. At 800℃, the contact angle of the Sn-3% Sc/Si₃N₄ system reduced to 0°, achieving complete wetting. Interfacial microstructural analysis revealed that a reaction layer approximately 1.3 μm thick formed at the Sn-3% Sc/Si₃N₄ interface at 800℃, primarily composed of ScN and ScSi compounds. Furthermore, the formation mechanism of the precursor film was identified as conforming to the rapid adsorption-thin layer diffusion mechanism. Thermodynamic and kinetic analyses indicated that the wetting behavior of the system was governed by the formation of ScN and ScSi. This investigation provides a theoretical foundation for enhancing the wetting and interfacial bonding of Sn-Sc alloys on Si₃N₄ ceramics.

Key words: interface, reactive wetting, rare earth element, kinetics, thermodynamics

摘要：

针对氮化硅（Si₃N₄）陶瓷与金属钎焊中润湿性差，活性组元界面活性不足的问题，提出以Sc替代传统Ti活性组元，采用改良座滴法，系统地研究了Sn-xSc［x=1%，2%，2.5%，3%（原子分数）］合金在700~800℃范围内对Si₃N₄陶瓷的润湿行为。实验结果表明，随着活性元素Sc的引入，Sn-xSc/Si₃N₄体系的接触角显著降低，并且表现出对温度和Sc浓度的强烈依赖性。在800℃时，Sn-3%Sc/Si₃N₄体系的接触角降至0°，实现了完全润湿。通过界面微观结构分析发现，在800℃下Sn-3%Sc/Si₃N₄体系界面处形成了约1.3 μm厚的反应层，主要由ScN和ScSi化合物组成。此外，还发现前驱膜的形成机制符合快速吸附-薄层漫流机制。热力学和动力学分析表明，体系润湿性是由生成的ScN和ScSi决定的。这一发现为优化Sn-Sc合金在Si₃N₄陶瓷上的润湿性和界面结合提供了理论依据。

关键词: 界面, 反应润湿, 稀土元素, 动力学, 热力学