Preparation of Ni-coated TiC particles using potential hydrogen (pH) for dispersion into a molten metal

Titanium carbide (TiC) particles have been coated with nickel (Ni) particles to increase compatibility between the TiC particles and the metal matrix based on Ni, leading to the improvement in the dispersion of TiC particles into a molten matrix, as functions of the potential hydrogen (pH) of TiC suspension, and the heat-treatment condition. The TiC particles were dispersed into the aqueous solution with various pH values, and then nickel nitrate (Ni(NO3)2) as a Ni precursor was added at the TiC suspension. As the pH is increased the content of Ni phase on the surface of TiC particle is increased, due to the increment of attractive force between the TiC particle and the Ni ion by the augmentation of negative value on the surface of TiC particle. The Ni-coated TiC particles heat treated at 500 °C under H2 atmosphere indicate the TiC and Ni phases only, whereas those heat treated at 1000 °C under Ar atmosphere show a titanium oxide (TiO2) with the TiC and Ni phases, which is resulted from the oxidation of TiC particle by oxygen contained in Ar gas. The dispersibility of TiC particles into a molten metal would be improved through the coating of Ni particles (or phase), inducing the improvement and reliability of mechanical properties.

Research highlights▶ TiC particles coated by Ni particles have been prepared using surface charge. ▶ The pH control is a very effective and successful technique for coating Ni phase. ▶ The coating efficiency of Ni particles onto TiC particles is maximized at the pH 12. ▶ The best heat treatment condition for the particles is 500 °C and H2 atmosphere.