Effect of micro-oxidation and Cu modification of C/C composite on microstructure and mechanical properties of C/C|Ti3Al joints

Abstract

In order to form the strong mechanical interlocking and improve the compatibility between interlayer and C/C composite, a porous structure with a series of annular gaps and Cu coating on C/C composite surface were designed and prepared by micro oxidation in the muffle furnace and magnetron sputtering, respectively. The C/C composite |Ti3Al joints were prepared by transient liquid phase (TLP) diffusion bonding. During the bonding process, the liquid phase flowed into the gaps, and the infiltration layer is formed between C/C composite and core interlayer. The infiltration layer mainly consists of C/C matrix, TiC and Ag (s, s), and the CTE of infiltration layer between that of C/C composite and interlayer. Therefore, the mismatch of thermal deformation between C/C composite and interlayer can be reduced, which can avoid high stress in the joint. After surface modification of C/C composite with micro-oxidation at 630 °C for 30min and Cu film, the wettability of liquid phase on C/C composite increased, and Ti–Cu phase formed in the core interlayer of the corresponded joints, which consumes the Ti atoms in liquid phase and causes a thin TiC layer. The shear strength of the joints increases from 34.58 MPa (the original joints) to 44.23 MPa (the pretreated C/C|Ti3Al joints) under optimized process (i.e. 880 °C, 10min), and the fracture not occurs in C/C composite but in joint area after pretreatment of C/C composite.