Study On Microstructure And Properties Of Nickel-based Coating Of Multi-field Composite Assisted Laser Cladding Carbonization Dock

With the rapid development of the global manufacturing industry,the working environment of important mechanical components is becoming increasingly complex.As the core part of die-cutting equipment,die-cutting tools are prone to wear,deformation,chipping and other failures in harsh working environments,mainly because the hardness of the tool is not enough and the wear resistance is poor.The use of laser cladding technology to manufacture or strengthen tools can significantly improve the hardness and wear resistance of tools and improve service life,but defect suppression and tissue control are still research hotspots.In this paper,Ni60,WC and BiFeO₃ were used as cladding materials,and nickel-based coatings were prepared on 45 steel substrates by field-assisted laser cladding technology.The influence mechanism of ultrasonic vibration,ultrasonic electromagnetic composite energy field,Bi Fe O₃ content and different magnetic field strengths under composite energy field on the cladding layer was studied by using the preset coating method and four sets of single-factor tests.Firstly,in order to study the influence of ultrasonic frequency on the microstructure and properties of Ni60/WC composite coating,a set of single-factor tests were carried out,and it was found that ultrasonic vibration could significantly reduce the porosity of the cladding layer and have a certain refinement effect on the microstructure.When the ultrasonic frequency is 32k Hz,the porosity in the cladding layer is about 0.40%,the average grain size of the cladding layer is about 0.241μm,the average microhardness of the cladding layer is about 957HV_1.0,the friction coefficient is about 0.60,and the wear mark width is about 0.601mm.Secondly,in order to further eliminate the porosity and crack defects of the cladding layer,the composite magnetic field stirring is based on the best ultrasonic frequency obtained above.It is found that after the composite magnetic field,the pores and crack defects in the cladding layer are further reduced.When the magnetic field strength of the composite energy field is 30m T,the porosity of the cladding layer reaches the minimum of about 0.08%,and the number of cracks is reduced to 2 to reach the minimum,at this time,the average microhardness of the cladding layer is about1008.4HV_1.0,the friction coefficient of the cladding layer is about 0.54,and the width of the wear mark is about 0.527mm.Finally,in order to further explore the effect of magnetic field strength under the composite energy field on the microstructure and properties of the cladding layer,different contents of Bi Fe O₃ powder are added to the cladding layer under the condition of optimal ultrasonic frequency,and it is found that the dilution rate of the cladding layer shows an increasing trend with the increase of Bi Fe O₃ content.When the added content of Bi Fe O₃ was 5%,there were no obvious pore defects in the coating,and the dilution rate was suitable（4.77%）.Then,on this basis,magnetic field stirring of different intensities is composite,and the results show that with the increase of alternating magnetic field strength,the aspect ratio of the cladding layer gradually increases.When the magnetic field strength in the composite energy field is 40m T,the microstructure is the most fine and uniform,the average microhardness of the cladding layer reaches the highest,about 925.2HV_1.0,the wear resistance reaches the best,the friction coefficient of the cladding layer is about 0.54,and the width of the wear mark is about 0.530mm.