Preparation Of Spherical Cast Tungsten Carbide Composite Powder And Research Of Its Applicability For 3D Printing

Tungsten carbide matrix composites are widely used in industrial fields because of their high hardness and strength.Among various forming technologies,selective laser melting?3D printing?is expected to be one of the technologies to achieve the requirements of complex morphology,so it is of great significance to the research on the technology of 3D printing tungsten carbide matrix composites.Due to the difference in appearance and uniformity between the raw powder needed for 3D printing and the traditional raw material,it is an urgent problem to prepare composite powder suitable for 3D printing.This thesis uses the electroless plating method for 3D printing high sphericity high uniformity of WC-W₂C-Ni composite powder,constituency of composite powder and laser melt forming research.Analyzes the WC-W₂C activation mechanism of electroless composite powder and metal layer growth mechanism,and discusses the various reagents and experimental environment influence on it,was prepared by optimum seeking method is suitable for the selection of laser molten compound powder,comparison and analysis the different 3D printing parameters on the influence law of forming material density,and the phase composition and microstructure of the composite material for the corresponding analysis,the conclusions are as follows:?1?The tungsten carbide particles treated with organic activation have good activity,and the activated tungsten carbide powder can obtain good coating and maintain good sphericity in the plating solution with different components through certain optimization and adjustment.The final optimization parameters:PH of 12.5,temperature of 85?,concentration of nickel sulfate of 360g/L,reducing agent sodium hypoxophosphate of 360g/L,and complexing agent sodium citrate of240g/L.?2?It is found that the laser power and scanning speed have a decisive influence on the energy input,which has a great influence on the density,bending strength and impact toughness of the material.The WC-W₂C-Cu-Ni composite material with good comprehensive properties can be obtained after the optimized treatment,and the properties of the composite material prepared by the traditional non-pressure impregnation method are improved by about 5-15%.?3?The mechanism of mechanical reinforcement was studied by means of TEM microanalysis.It was found that the strengthening methods were mainly composed of nanometer strengthening and nail-like tissue strengthening.Nanometer tungsten carbide particles are uniformly distributed in the matrix,which improves the hardness of the material to a certain extent,and creates an obvious interface with the matrix to preserve the toughness of the material to a certain extent.The tungsten carbide nailing structure firmly fixed the unmelted tungsten carbide particles in the matrix through the phenomenon of"rooting",which enhanced the skeleton function of tungsten carbide.