Preparation And Mechanism Of Micro-nano Fe-Co-Cu Prealloyed Powder

Pre-alloyed powder is widely used in diamond tool manufacturing and powder metallurgy industry.This paper prepares a kind of Co pre-alloyed powder by mechanochemical alloying method.The main research is the mechanochemical alloying method to prepare micro-nano Fe-Co-Cu pre-alloy.Production process and experimental mechanism of powder.The production methods of pre-alloyed powder mainly include co-precipitation method,atomization method and mechanical alloying method.In contrast,the mechanochemical alloying method has a simple production process and a short production cycle.Using metal oxides as raw materials can effectively reduce production costs,and the entire production process is pollution-free,which is suitable for large-scale production.This paper first calculates the hydrogen reduction kinetics of three metal oxides,Fe₂O₃,Co₃O₄ and CuO,and calculates the reduction temperature of the prealloy powder.Secondly,a precursor powder is prepared by ball milling a mixture of three metal oxides by a high-energy ball milling method.The precursor powder is obtained by controlling the ball-material ratio and the ball milling time with a uniform particle size distribution and a uniform chemical composition.Finally,the precursor powder is reduced by hydrogen to obtain a pre-alloyed powder,and the optimal process conditions for producing the pre-alloyed powder are obtained by controlling the reduction temperature and the reduction time.According to the thermodynamic analysis of the reduction reaction,it can be known that the hydrogen reduction metal oxide powder follows the unreacted nuclear model.The reaction starts from some active points of the powder particles and can be carried out at a lower temperature,but the reaction speed is slower.The minimum reduction temperature of the three metal oxides was obtained by kinetic calculation as a reference for the reduction temperature of the pre-alloy powder.High-energy ball milling not only refines the particle size of the powder,but also increases the distortion energy of the powder,so that the reduction reaction can be carried out at a lower temperature.At the same time,the Cu0.27Co2.7₃O₄ phase is formed after ball milling,which further reduces the reduction temperature.The reduction temperature and time are the most important factors in the reduction process.Both the reduction temperature and the reduction time increase the reduction rate of the precursor powder,but the particle size of the powder also increases.Therefore,it is very important to control the reduction time and temperature.The size of the hydrogen flow during the reduction process has little effect on the pre-alloy powder,so no further research has been done.Through theoretical analysis and experiments,the optimal preparation conditions for preparing micro-nano Fe-Co-Cu pre-alloyed powders are obtained,namely,the ball-to-material ratio is 15: 1,and the precursor powder prepared by ball milling for 2 h can be reduced at 650 ? for 60 min.A prealloy powder having a particle size of 0.55 ?m was obtained.The pre-alloy powder obtained under this process condition has high alloying degree,low oxygen content,uniform composition and particle size,lower production cost,no pollution during production process,and is suitable for large-scale industrial production.