Synthesis of ultrafine zirconium carbide particles by SHS in an Al–Zr–C system: Microstructural evaluation and formation mode

Abstract

Due to exhibiting the desirable mechanical and chemical properties, ZrC is widely applied as the multifunctional materials related to reinforced-particulates, engineering structures and electrical devices. Using self-propagating reaction technique, the ultrafine even nanosized ZrC particles were in situ fabricated in an Al–Zr–C powders with 30 and 40wt.% Al contents, but the ZrC-forming reaction failed to be triggered at 50wt.% Al content. The Microstructural characteristics of synthesized as-products, coupled with the formation mode of ZrC phase, was considered together. The results reveal that the ZrC particles size is highly influenced by Al content in the compact. For 30wt.% Al content, the size is about 150nm, while for 40wt.% Al content, the clean ZrC nanoparticles with well-developed morphology is about 60nm. The reaction–precipitation mechanism is responsible for the formation of ultrafine ZrC particles. DTA analysis, combined with the water-quenched treatment during SHS, strictly demonstrated the reaction habit of Al–Zr–C system. It is accepted that the reaction between Al and Zr to form ZrAl3 phase initially take place, and then the reaction between molten ZrAl3 phase and C to synthesize ZrC phase is followed. Al has been playing an important role in controlling the reaction habit of Al–Zr–C system, not only serving as a diluent to inhibit the ZrC particles from coarsening, but also as an intermediate reactant to participate in the total reaction process.