碳热还原燃烧前驱物合成纳米碳化钨(WC)基粉末的研究

Aiming at the need of high-quality powder in the field of nano-crystalline or untrafine-crystalline tungsten carbide（WC）based composite material, this project puts forward the idea of preparing WC based nanopowder by combining low temperature combustion synthesis and carbothermal reduction. The thermodynamics and kinetics of the combustion synthesis process are investigated in order to reveal the combustion mechanisms and major influence factors. The influences of the raw materials ratio, ignition condition, combustion atmosphere and the other factors on the phase constituent, homogeneity, particle size and morphology of the obtained precursor are investigated. The reaction mechanisms and thermodynamics of the carbothermal reduction reaction of the combustion synthesized precursor are studied in details. The control rules about the size, structure and dispersion of WC, metal binders, and grain growth inhibitors are understood. This project is expected to broaden the application of low temperature combustion synthesis method, to enrich the theory and practice of combustion synthesis field, and to provide guidance to fabricate high performance non-oxide powder with several compositions.

本项目针对纳米或超细晶碳化钨（WC）基复合材料对高质量原料粉末的需求，提出将碳热还原与湿化学低温燃烧合成相结合制备纳米WC基粉末的研究思路。研究燃烧合成热力学和动力学，揭示燃烧合成前驱物的机理及控制因素，确立原料配比、点燃条件和燃烧环境等因素对前驱物物相、成分、粒子粒度和形貌的影响机制；研究燃烧前驱体各组分碳热还原反应机制与热力学，揭示碳化钨相、金属粘结相以及晶粒长大抑制剂等组分的粒度、结构和分布均匀性控制机制，建立碳热还原燃烧前驱物合成粒子细小、结构可控、分布均匀的纳米WC基粉末的工艺原理和技术基础。该研究拓展了低温燃烧合成的应用，丰富了燃烧合成领域的理论与实践，并将为发展新型多组分高性能非氧化物陶瓷粉末制备方法提供借鉴。

具有优异性能的纳米晶WC硬质合金在电子信息、计算机、汽车工业、航空航天、国防军工等众多领域有着巨大的应用潜力。纳米WC粉末的制备是生产纳米晶WC硬质合金的基础和关键。本项目以低价、易得的WO3和碳黑为原料，采用简便、短流程的碳热还原工艺合成了粒径小(≤100 nm)，分散性好、粒度分布窄、纯度高(＞99.9 wt.%)、化合碳含量(6.10 wt.%)接近理论值且游离碳含量低（0.09 wt.%)的纳米WC粉末，并详细研究了纳米WC粉末的合成过程、成核和生长机制。本方法不仅显著降低了加工温度(1100 °C)，缩短了保温时间(3 h)，还厘清了各要素的耦合作用机制，实现了对WC粉末特性的精确控制，并提供工艺技术和理论依据。