Preparation of Spraying Powders and Microstructureof MolybdenumDisilicide Coating

With the size of 1―2μm MoSi2powder as raw material, MoSi2 powderideal for air plasma spraying was prepared by spray drying and vacuumsintering. By using MoSi2 powders (9.68μm ) and agglomeration powders (38―72μm) as the spray feedstock, MoSi2 coatings weresuccessfully prepared using air plasma spraying. The phase composition and microstructure of the coatingwere studied.The results show that the mobility and loosedensity of theagglomeration powders sintered at 1300 for 1h are 17.1s/50g and 2.1g/cm3, respectively. Compared with the unsintered powders, the mobility and loose density of the sintered agglomeration powders increaseby 57.0% and 46%, respectively. XRD patterns shows the main phasesare Mo and Mo5Si3 phases in the coating prepared by thepowders with the size of 9.68 μm.In case of spraying withagglomeration powders, the main phase of the dense coating is MoSi2. The meshmicrostructure of molybdenum―rich phase is produced in the coatingprepared by the agglomeration powders.