Investigate the effect of C coating on the wetting and reaction mechanism of Sc₂W₃O₁₂ and AgCuTi filler

Mitigating the interface reaction between negative thermal expansion materials and filler metals is crucial for enhancing the functionality of negative thermal expansion materials. However, the general approach to mitigate interface reaction, such as minimizing both reaction time and temperature, will result in insufficient metallurgical reactions necessary to establish reliable connections during the brazing process. Through wetting process analysis and first-principles calculations, the effect of C coating on the wetting and reaction mechanism of Sc₂W₃O₁₂ and AgCuTi filler is revealed. The wetting experiment indicates that the C coating not only improves the wettability but also mitigates the interface reaction. According to the interfacial microstructure, 18 kinds of Ti/Ti₃O₅ (001) and 3 kinds of Ti/TiC (100) adsorption systems are constructed to calculate the adsorption characteristics. According to the calculations, the Ti/TiC (100) system has lower adsorption energy than Ti/Ti₃O₅ (001) system, indicating that Ti atoms are more easily adsorbed on the TiC surface. The charge density difference contour shows that the charge repulsion on the TiC surface restricts the entry of Ti atoms. This work provides new insights into the mechanism of how the C coating to reduce interfacial consumption of the negative thermal expansion materials.