Highly Efficient and Low-Temperature Preparation of Plate-Like ZrB₂-SiC Powders by a Molten-Salt and Microwave-Modified Boro/Carbothermal Reduction Method.

To address the various shortcomings of a high material cost, energy-intensive temperature conditions and ultra-low efficiency of the conventional boro/carbothermal reduction method for the industrial preparation of ZrB₂-SiC powders, a novel molten-salt and microwave-modified boro/carbothermal reduction method (MSM-BCTR) was developed to synthesize ZrB₂-SiC powders. As a result, phase pure ZrB₂-SiC powders can be obtained by firing low-cost zircon (ZrSiO₄), amorphous carbon (C), and boron carbide (B₄C) at a reduced temperature of 1200 °C for only 20 min. Such processing conditions are remarkably milder than not only that required for conventional boro/carbothermal reduction method to prepare phase pure ZrB₂ or ZrB₂-SiC powders (firing temperature of above 1500 °C and dwelling time of at least several hours), but also that even with costly active metals (e.g., Mg and Al). More importantly, the as-obtained ZrB₂ particles had a single crystalline nature and well-defined plate-like morphology, which is believed to be favorable for enhancing the mechanical properties, especially toughness of their bulk counterpart. The achievement of a highly-efficient preparation of such high-quality ZrB₂-SiC powders at a reduced temperature should be mainly attributed to the specific molten-salt and microwave-modified boro/carbothermal reduction method.