Pre-infiltration and brazing behaviors of Cf/C composites with high temperature Ti[sbnd]Si eutectic alloy

Abstract

A novel method is developed to join carbon fiber reinforced carbon composites (Cf/C composites) via a two-step approach using Ti14Si86 metal foil as the joining material. The infiltration behavior, joint microstructure, interface reaction, fracture characteristics and joining mechanism are investigated. The preparation of the almost compact deposit layer and the infiltration carbide can immediately heal the pores of Cf/C composites and form the gradient composite structure, which can effectively minimize the impact of the coefficient of thermal expansion (CTE) mismatch between the outer reaction layer and the carbon matrix and avoid the excessive filler infiltration in the brazing step. The brazing process reveals that the growing SiC interface and TiSi eutectic structure in the seam also behave as a graded CTE composite structure, which is beneficial for strengthening the joint. Compared with direct brazing, this method can obtain more reliable Cf/C composites joints due to strong interfacial bonding and the gradient structure. As a result, a favorable shear strength of 26 MPa is achieved within 10 min at a brazing temperature of 1400 °C.