Research On Preparation Technology And Performance Of Wear-resistant And Corrosion-resistant Coating For Magnetic Pump

The magnetic drive pump is a liquid transportation equipment that transmits torque through magnetic force.In practical engineering applications,the parts in the pump will be corroded by strong acid and strong alkaline liquids and excessive wear during highspeed rotation.At present,the most used method is to die-cast cemented carbide with high performance on pump parts,but cemented carbide is brittle,has poor impact resistance,and has low bonding force with parts,so it is easy to break and fall off.In this paper,the composite alloy cladding layer is obtained by cladding Ni and Co-Crbased alloy cladding layers on the surface of Fe316L matrix,and adding different mass fractions of WC hard phases to them respectively.Explore the influence of WC hardness on the microstructure of the cladding layer and the enhancement mechanism of wear resistance and corrosion resistance,so as to determine the optimal Ni-WC,CoCr-WC composite powder ratio to meet the requirements of magnetic pump parts in the Material performance requirements in engineering applications.The specific research content and main conclusions are as follows:(1)The Ni,Co-Cr-based alloy powder with high performance in the self-fluxing alloy powder is used as the material,and the optimal laser process parameters are selected through the orthogonal test powder for laser cladding.The results show that the main phases of Ni-based alloy cladding layer are γ-(Ni,Fe),FeNi3,Cr23C6,M23C7,Ni4B3,the diffraction peaks are mainly γ-(Ni,Fe)solid solution,and carbides such as Cr23C6 and M23C7 have Improve the hardness and make the microstructure of the cladding layer more compact.The main phases of the Co-Cr-based alloy cladding layer are γ-Co,M23C6,Cr7C3,FeNi3,and Co3W,which are basically the same as the elemental compositions in the alloy powder,but also contain FeNi3 and other phases.The microstructure and grains of Ni-based and Co-Cr-based alloy cladding layers mainly include dendrites,cellular crystals,strip crystals and interdendritic network structures,and their hardness is greater than that of the matrix Fe316L.In the friction and wear test,the wear resistance of Ni-based alloy cladding layer is stronger than that of Co-Cr-based alloy cladding layer,but the wear mechanisms of both are mainly oxidative wear and adhesive wear.In the electrochemical corrosion test,the corrosion resistance of the Ni-based and Co-Cr-based alloy cladding layers is stronger than that of the base Fe316L,and the Tafel curves of the two cladding layers show a positive potential shift and passivation range,with good Corrosion resistance.(2)Based on the experiments of pure Ni,Co-Cr-based alloy cladding layers,WC hard phases with different mass fractions were added to them.The results show that when the WC powder is added,the Ni-WC composite cladding layer has phases with higher hardness such as W2C and WC.With the increase of the mass fraction of the WC hard phase,the diffraction peak increases gradually,and Ni4B3 appears.this new boride.When the WC hard phase is added to the Co-Cr alloy powder,the carbide phases with higher hardness such as Co3W,CCo2W4,W2C and WC appear in the cladding layer.The morphology of WC particles in the cladding layer is mainly divided into two types,one is a slightly dissolved-diffusion type,and the other is a dissolution-diffusion type.The effect of grain refinement.With the increase of WC content,the hardness and wear resistance of the two composite cladding layers are enhanced to different degrees.In the electrochemical corrosion test,the Ni-WC and Co-Cr-WC composite cladding layers after adding different mass fractions of WC hard phases have stronger corrosion resistance and potentiodynamic polarization than pure alloy cladding layers.The passivation interval in the curve is also longer than that of the cladding layer without WC addition,and its electrochemical corrosion density decreases continuously with the increase of WC mass fraction.(3)Using Ni-30%WC and Co-Cr-30%WC,two kinds of composite alloy powders were used to prepare composite cladding layer on the magnetic drive pump shaft,pump ring and other parts.The clad magnetic pump shaft and pump ring are machined and surface rinsed.The cladded pump shaft is assembled into a 32CQ-25F engineering plastic magnetic drive pump,which runs continuously for 100 days in the conveying system.Observing the surface morphology of the pump shaft and pump ring after the installation test,it can be found that there are no obvious wear marks,corrosion pits,cracks,bending and other defects in the cladding layer,indicating that the two types of Ni-30%WC and Co-Cr-30%WC are The composite alloy cladding layer has the advantages of high hardness,high wear resistance,high corrosion resistance,etc.,and can meet the performance requirements in the engineering application of magnetic pump parts.