Wetting behavior of graphite and CFC composites by Cu-Ti compacts

The wetting behavior of Cu-Ti powder compacts with 22 wt % Ti and 50 wt % Ti on carbon materials, including graphite and carbon fiber reinforced carbon composites (CFC), has been investigated in a vacuum using the sessile drop method. The equilibrium contact angles of Cu-22Ti (containing 22 wt% Ti) on the graphite and the CFC substrates at 1 253 K are 32° and 26°, respectively, whereas the equilibrium contact angle of 9° is obtained for Cu-50Ti (containing 50 wt% Ti) on both the graphite and the CFC substrates at 1 303 K. Microstructural analysis of the wetting samples shows that a thin TiC reaction layer is developed at the interfacial area and Ti-Cu intermetallic compounds are formed over the reaction layer. The investigation on the spreading kinetics of Cu-Ti compacts on carbon materials substrates at fixed temperatures reveals that the spreading is controlled by the interfacial reactions in the first stage and then by the diffusion of the active Ti from the drop bulk to the triple line in the later stage. The spreading is promoted by the intense reaction at higher Ti concentrations.