Preparation of micro-nano Mo(C, N) powders by low temperature carbothermal and micro-positive pressure of nitrogen

The carbonitride of Mo (Mo₂C or MoN) is important to improve the structural properties of metal matrix composites. The solid solution of Mo(C, N) combined the characteristics of metal and carbonitride of Mo shows the better structural properties of metal matrix composites. The micro-nano Mo(C, N) spherical solid solution powders were prepared by mechanical alloying technique and carbothermal method at low temperature and low-pressure of nitriding in this study. The effects of mechanical force and nitriding conditions on the structures and particle sizes of powders were studied by thermogravimetric analysis-differential scanning calorimetry (TG-DSC), X-ray diffraction (XRD), and scanning electron microscope (SEM).The results show that, after high-energy ball mill for 9 h, enough mechanical force can refine the mixture powders of MoO₂ and carbon, improve the interface energy, and increase the defects, which can provide the activation energy of MoC-N chemical adsorption to transform to the micro-nano Mo (C, N) solid solution powders. Moreover, it can change the unsaturation of electrons on the surface of Mo atoms and promote the Mo-N bonding when the mixture powders are carbothermal at the condition of micro-positive pressure of nitrogen. Finally, the micro-nano Mo(C, N) spherical solid solution powders are prepared at the N₂ pressure of 0.2 MPa and the temperature of 850 ℃; it can effectively reduce the energy consumption and save cost at this low carbothermal temperature, showing the important prospects of industrial applications.