Effect of mechanical activation of reagents’ mixture on the high-temperature synthesis of Al2O3–TiB2 composite powder

A three-step synthesis process of submicron boron carbide powders using microwave energy

“…Figure 9a shows the DSC/TG analysis of as-mixed powders of sample S 1 , which were exposed to heating up to 1000°C. As can be seen, two successive endothermic peaks were revealed below 300°C, which are related to the thermal decomposition and dehydration of boric acid [26,27] and TG analysis shows that this occurrence led to an about 20 % mass loss. In fact, this shows that about 20 % mass increase might be occurred due to the moisture sorption during mixing and before TG analysis.…”

“…This means that acid leaching that removed the MgO phase, which seems to behave like cement toward B 4 C particles, led to the formation of pure B 4 C phase with a lower average particle size. High-energy collisions between the reactant powders and balls inside a ball mill could lead to the mechanical activation of the powders, which may enhance the kinetic of the reactions as a result of the mixing and refining of the microstructure and increase the energy level of the starting powders, allowing the reaction to occur at much lower temperatures than normally required [26,30,[43][44][45][46]. Figure 9a shows the DSC/TG analysis of as-mixed powders of sample S 1 , which were exposed to heating up to 1000°C.…”

“…Thus, the drawbacks of this process lie in high-energy consumption and low product purity [19][20][21][22]. SHS process has been used so far as an inexpensive process, in which highly exothermic reactions between the constituents become self-sustaining and proceed via a combustion propagation wave through an entire sample, providing an attractive low cost alternative to conventional methods of producing advanced materials [23][24][25][26][27]. It should be noted that these exothermic reactions could be simply confined using diluents, etc., to avoid damaging the combustion chamber.…”

One-Pot Synthesis of Alumina-Titanium Diboride Composite Powder at Low Temperature

“…To eliminate Al18B4O33, the excess Al was further increased to 30 wt%. Unfortunately, some Al3Ti was formed instead (Figure 3d), implying that there was no sufficient supply of B in the system, due to probably evaporation loss of B2O3 at such a relatively high temperature [43,44]. To eliminate Al 18 B 4 O 33 , the excess Al was further increased to 30 wt%.…”

“…Nevertheless, the formation of phase-pure Al 2 O 3 -TiB 2 was still not achieved.To eliminate Al 18 B 4 O 33 , the excess Al was further increased to 30 wt%. Unfortunately, some Al 3 Ti was formed instead (Figure3d), implying that there was no sufficient supply of B in the system, due to probably evaporation loss of B 2 O 3 at such a relatively high temperature[43,44].…”