Study On The Coating Technology Of 3540Fe/CeO₂ With Ultrasonic Vibration Assisted Laser

Aiming at the problem of shortening the service life of the roll parts due to the wear failure,this paper adopts the new process method of vacuum sintering assisted laser cladding,and chooses 42CrMo steel as the base material for laser cladding experiment.The feasibility and mechanism of high performance coating by air-supported ultrasonic vibration assisted laser cladding are discussed by analyzing the macroscopic morphology,microstructure,phase composition and mechanical properties of the coating prepared by composite technology.And compares the performance of the composite coating prepared by applying ultrasonic vibration at different angles,which has been explored for the innovative research of laser cladding assistant technology.It also provides a new research idea for repairing roll parts by laser cladding,obtaining no crack,no stomata,high hardness and high wear resistance composite coating,which has important guiding significance.Firstly,the mechanism of ultrasonic welding assisted laser cladding is studied in this paper,and the characteristics of ultrasonic propagation in air are analyzed.It is pointed out that the effect mechanism of ultrasonic wave on laser cladding is mainly cavitation effect and thermal effect.The formation process of cavitation bubble from formation to fracture is analyzed,and cavitation effect is simulated by water droplet simulation,At the same time,the source of the heat effect is the friction heat generation in the molten pool.On the basis of the theoretical analysis,the ultrasonic vibration horn is selected and calculated to ensure the experimental requirements with sufficient amplification factor and work stability,and the ultrasonic vibration and the angle adjustable laser vibration is designed.The experimental system provides a reliable guarantee for the study of different angles of ultrasonic vibration assisted laser cladding experiments.Then,the technological parameters and powder ratio of 3540Fe/CeO₂ iron-based alloy coating on the surface of 42CrMo steel substrate are studied experimentally.Design orthogonal test.By comparing the hardness and wear resistance of the coating,the optimum process parameters of the laser single channel cladding are obtained:laser power 1.1KW,out of focus 30mm,scanning speed of 4mm/s.On the basis of this,a multi-channel experiment is carried out.By comparing the surface and sectional shape of the coating and the flatness of the joint interface,it is determined that the optimal overlap ratio of multi-channel laser cladding is 50%.After the combination of the best process parameters,The fusion experiment is carried out with a mixture of CeO₂ rare earth elements and 3540Fe base powder.The influence of the different addition of CeO₂on the performance of the cladding layer is studied,and the results show that the optimal addition of CeO₂ is 1.2%.In this experimental condition,the cladding layer is closely organized,the crystal distribution is uniform,the coating hardness and wear resistance are improved effectively.Finally,the experiment of 3540Fe/CeO₂ high performance cladding is carried out by ultrasonic vibration assisted laser cladding under the condition of determining the optimum technological parameters and powder ratio of laser cladding.The effects of ultrasonic vibration on the macroscopic morphology,microstructure,composition and mechanical properties of the cladding layer are compared,using asana microscope,scanning electron microscope,XRD diffraction,microhardness tester.The results show that the microstructure refinement effect of the cladding layer is more remarkable by the cavitation effect and the thermal effect of the ultrasonic vibration,Equiaxial crystals and small needle dendrites are transformed from a large cytoplasm with no ultrasonic vibration and small dendritic crystal.Pores and cracks disappear,while the coating to obtain high hardness and wear resistance,phase structure is not affected.The cladding layer obtained under the experimental conditions of 0°,30°,45°,60°and 90°,respectively,shows that the cladding layer performance is the best at 45°under ultrasonic conditions,and the cladding surface is flat,the microstructure of the microstructure consists of fine equiaxed grains and dendrites,the most refined uniformity,the hardness increased by62%to 1148HV,the abrasion resistance is 2 times higher than that of the ultrasonic vibration The coefficient is reduced by nearly 50%.