Microstructures and interfacial behavior of Ag-CuO/AlN system by air wetting and brazing: Experiments and first-principles calculations
Qinhan Guo, Shunjian Xu, Xiangzhao Zhang, Xinyi Gui, Yudi Qiu, Ziyi Guo, Yin Zhou, Hao Wan, Guanjun Qiao, Guiwu Liu
Abstract
Reactive air wetting and brazing of AlN ceramic were performed using Ag-(0 20)at%CuO fillers. The wettability , joint mechanical properties and microstructural evolution were investigated, and the related surface energies, interfacial stability and electronic properties of Ag-CuO/AlN system were evaluated comprehensively by density functional theory (DFT) calculations. With the CuO content increasing, the contact angle of Ag-CuO/AlN system reduces significantly from over 120° to <10°. The variation of joint strength is closely related to the formation of interfacial Al 2 O 3 layer and the thickness of Ag layer, and the average shear strength of AlN/AlN joint arrives at the maximum of 57.5 MPa. Moreover, the DFT calculations demonstrate that the Ag(111)/Al 2 O 3 (001) and Ag(111)/CuO(001) interfaces present stronger and more stable interfacial bonding than the Ag(111)/AlN(001) interface owing to the formation of O-Ag ionic bond , suggesting that the Ag/AlN interface can be effectively strengthened due to the addition of CuO and in-situ oxidation of AlN substrate.