reaction of Ti–C and fuse the reinforcement phase onto the substrate
surface.
As we known, the term thermite reaction is used to describe a
much broader class of exothermic reactions. There are a number
of factors involved in the selection of a reducing agent for a particular
oxide. The tendency for a metal to reduce an oxide depends
on the free energy of formation of its oxide. Element Si as a common
reducing agent shows negative Gibbs free energies of oxide
formation over a wide temperature range. Goldschmidt used intermetallic
reactants (Ca–Si, Ca–Al, and Mg–Si) instead of aluminium
as reducing agents in order to form lower melting compounds [10].
In this work, we employed this approach by using Si partly instead
of aluminium as reducing agents to lower the melting point of aluminium
oxide. In addition, our previous study showed that adding
some slagging medium composed of boron oxide into the thermites
could facilitated the separation process of aluminium oxide
product from molten metal [11]. The binary Al2O3–B2O3 equilibrium
diagram shows that B2O3 can reduce the melting point of
Al2O3 significantly by forming Al18B4O33 or Al4B2O9 phases with
low melting points. Because of low melting points, those phases
could rapidly separate from molten metal products and lift to the
top owing to its lower density. Therefore, the pure molten metal