Wetting and interfacial reactivity of graphite by liquid TiCuNi

Understanding the wetting and interfacial reactivity of graphite in contact with molten alloys is important to optimize brazing or to prepare carbon-based composites and coatings. In this work, the isothermal wetting of graphite substrates by a molten Ti-based alloy, namely TiCuNi (Ti: 70 wt.%), was tested at 1000 °C at different holding times by the sessile drop method with the aim to understand the interfacial reactivity. A final contact angle of 15° was achieved after 60 min of liquid-solid contact as a result of spreading kinetics. A thorough microstructural characterization by SEM and TEM was performed and evaluated with the help of the relevant phase diagrams: a limited interfacial reactivity to form TiC particles at the metal/graphite interface occurred. The interfacial compounds grew with time and determined the spreading of the liquid on the graphite substrate which resulted to be reaction-limited.