结构-反应协同调控强化纳米WC-Co粉体制备过程及其机理

超细/纳米晶WC-Co类硬质合金具有优异的力学性能，是该领域开发的重点和热点。粒径、组分分布均匀的纳米/超细WC-Co粉体是获得超细/纳米硬质合金的首要关键因素。然而，现有技术存在高温形成不利于烧结的η相及纳米Co颗粒熔融粘结引起组分分布不均匀，而低温扩散传质-反应速率慢的关键技术问题。因此，本项目拟通过结构-反应协同调控强化其低温制备过程，避免形成η相及Co颗粒粘结，结合流态化技术的优势和氧化钨反应过程中的结构变化特性，提出流态化预还原造孔-融合流态化化学气相沉积钴的深还原碳化新思路。以WO3为原料，通过预还原调控结构建立其多孔结构调控机制，分析深还原碳化-沉积钴过程颗粒结构演化规律与流化性能的关系，以及各因素对产物结构、物相、成分的影响规律，揭示反应过程路径机理，建立纳米WC-Co制备过程调控机制，最终获得粒径、组分分布均匀无η相纳米WC-Co粉体，从而形成其制备过程强化的理论方法。

Ultrafine/nanocrystalline WC-Co cemented carbide has excellent mechanical properties, which is the focus and hot spot of the development in this field. Ultrafine/nano-sized WC-Co powder with uniform particle size and component distribution is the primary key factor to obtain ultrafine/nano-sized cemented carbide. However, there are some key technical problems in the prior art, such as the formation of η phase which is not conducive to sintering and non-uniform distribution of the components caused by the adhesion of nano-sized Co particles at high temperature, the slow diffusion mass transfer reaction rate at low temperature. Therefore, the aim of this project is to intensify the low-temperature preparation process through the structure-reaction coordinated control to avoid the formation of η phase and the adhesion of Co particles, combine with the advantages of fluidization technology and the structural change characteristics in the reaction process of tungsten oxide, put forward a new idea about making pores by fluidization pre-reduction and deep reduction-carbonization of pre-reduced particles combined with fluidization chemical vapor deposition cobalt. By using WO3 as raw material, its porous structure regulation mechanism will be established by pre-reduction. The relationship between particle structure evolution and fluidization performance in the process of deep reduction- carbonization and cobalt deposition will be analyzed, as well as the influence of various factors on the product structure, phase and composition. The reaction path and mechanism will be revealed and the regulatory mechanism of nano-sized WC-Co powder preparation will be established. Finally, the nano-sized WC-Co powder with uniform particle size and component distribution without η phase can be obtained. Accordingly, the theory and method of strengthening the preparation process of nano-sized WC-Co powder can be developed.