Microstructure And Properties Of Mo₂FeB₂-based Cermets Prepared By Liquid Phase Sintering

Mo₂Fe B₂-based cermet is a high-performance composite material with high hardness,high wear resistance,good high temperature stability,and excellent electrical conductivity.It has broad application prospects in the field of high hardness and high wear resistance.In this paper,low-cost ferromolybdenum powder,boron carbide powder,and iron powder are used as raw materials to prepare Mo₂Fe B₂-based cermets by in-situ reaction sintering.X-ray diffraction?XRD?,scanning electron microscope?SEM?,X-ray energy Spectroscopy?EDS?and mechanical property analysis have systematically analyzed the relationship between the sintering process,microstructure and mechanical properties of Mo₂Fe B₂ based cermets.This research mainly did the following work and obtained the following results:The phase transition process of Mo₂Fe B₂-based cermets,and the effects of sintering temperature and holding time on the structure and properties of Mo₂Fe B₂-based cermets were studied.The results show that when Mo₂Fe B₂ is prepared using ferromolybdenum powder,boron carbide powder and iron powder as the basic components,a solid phase reaction occurs at a temperature of 896?.The reaction process is Fe and B₄C to form Fe₂B,and Mo reacts with Fe₂B to obtain Mo₂Fe B₂.When the sintering temperature is 1280?,the temperature is kept for 30 minutes.The sample shrinks uniformly and has a dense structure.The overall mechanical properties are good.The hardness is 84.1HRA and the bending strength is 670MPa.The Mo₂Fe B₂-based cermet prepared by this method has structural defects and the causes of formation.The results show that the defect phase is the combination of B₄C particles and impurities,which makes it unable to continue to participate in the reaction to synthesize Mo₂Fe B₂.With the increase of the sintering temperature and the extension of the holding time,significant changes occur.The effect of the additive La B₆ on the structure and properties of Mo₂Fe B₂-based cermets was studied.The results show that La B₆ acts on the Mo₂Fe B₂ hard phase to prevent the abnormal growth of Mo₂Fe B₂grains,and also acts as a defect phase and has a certain elimination effect on it.When the addition amount of La B₆ is 6%,the effect of eliminating the defect phase is the best,the grain structure is evenly distributed,the mechanical properties of the cermet are the best,the bending strength of638MPa,and the hardness of 90.5HRA.