Effect Of Different Salt Content On Purity And Particle Size Of Salt-assisted Combustion Boron Powder And Its Mechanism

The application of B powder in the fields of aerospace,defense,military,chemistry and metallurgy is very promising,playing an increasingly important role.The performance of B powder is mainly related to its purity and particle size.High purity and small particle size are of great significance to further improve its performance.The purity and particle size of B powder are related to the preparation method,and its performance can also be affected by changing the parameters of the preparation method.This paper mainly uses the salt-assisted combustion synthesis method to prepare amorphous B powder on a large scale under the premise of?fixed material amount 1kg,Mg excess 10wt.%,Material molding pressure are 45MPa?,add and change the diluent The added amount of KCl,MgCl2 and NaCl,the salt-assisted combustion synthesis method is used to prepare B powder with higher purity and finer particle size.The prepared B powder was characterized by XRD,EDS,ICP,chemical analysis method,SEM,laser particle size analyzer,DSC and TEM,etc.The optimal technology was prepared by studying the preparation of B powder with different molding pressure of reactive materials and different Mg content in excess;Then study the influence of different diluents KCl,MgCl₂and NaCl on the phase,micro-morphology,purity and particle size of the prepared B powder and the mechanism of action.The main content and results of this article are as follows:1.In the Mg-KCl-B2O3 reaction system:the product after leaching contains the target product B powder and a small amount of Mg3B2O6 impurities that cannot be washed away.Powder B is amorphous.With the addition of 10%of KCl to 50%,the purity of the product B powder first increases and then decreases.When the KCl content is 30%,The highest purity is94.58wt.%.The addition of diluent KCl effectively reduced the particle size of B powder and weakened the agglomeration between B powder.As the amount of KCl added increases,the particle size of B powder gradually decreases.When the KCl content reaches 50%,The particle size reaches the minimum value of 0.73?m.2.In the Mg-MgCl₂-B₂O₃ reaction system:the product after leaching is also the target product B powder and a small amount of Mg₃B₂O₆ impurities that cannot be washed away.Powder B is also amorphous.With the addition of 10%of MgCl2 to 50%,the purity of the product B powder gradually decreases.When the MgCl₂ content is 10%,The purity reaches the highest value of 94.48 wt.%.The effect of adding diluent MgCl₂ on the particle size of B powder is more significant than that of KCl.The amount of MgCl₂ continues to increase,and the particle size of powder B gradually decreases.When the MgCl₂ content reaches 50%,The particle size reaches the minimum value,which is 0.69?m3.In the Mg-NaCl-B2O3 reaction system:The product after leaching contains the target product B powder and a small amount of Mg3B2O6 impurities that cannot be washed away.Powder B is amorphous.With the addition of 30%of NaCl to 50%,the purity of the product B powder is increased first and then decreased.When the NaCl content is 30%,The highest purity is 94.36wt.%.The addition of diluent NaCl effectively reduces the particle size of B powder and weakens the agglomeration between B powder.With the addition of 30%NaCl and 50%,The particle size of B powder gradually decreased.When the NaCl content reaches50%,The particle size reaches the minimum value of 0.72?m.By changing different preparation parameters,it is possible to control the purity and particle size of B powder.Under the optimal conditions of adding KCl,MgCl₂ and NaCl,the B powder prepared on a large scale has reached the standard of 92B,very close to 95B.