| Thermal spraying-laser in situ reaction as an important surface modification technology,It improves the wet-ability and the bonding properties between the coating and the substrate.It makes the coating tissue small,evenly distributed,so the toughness,corrosion resistance,wear resistance of coating are improved.Duing to the high-density laser beam transient heat input when the progress of laser in situ is reacting,there will produce a lot of thermal stress and deformation after the completion of the laser,the residual stress will affect the life of the parts.Therefore,it is necessary to calculate the stress at the interface between the coating and the substrate when the laser preparation is completed.In this paper,the temperature field,stress field and stress field which at different service temperatures during the preparation of the composite ceramic coating on the surface of CLAM steel are studied by using the finite element simulation:1.Ti powder,CrFe powder,FeAl50 powder according to the mass fraction of 1:2:2 ratio is dubbed to composite powder,Al2O3-TiO2composite ceramic coating was prepared on the surface of CLAM steel by thermal spraying and laser in situ reaction.The result shows:the surface of the Al2O3-TiO2 coatings are relatively smooth,there no holes,cracks and other defects,The composition of the phase are Al2O3,TiO2,Fe2TiO5,Fe-Cr,(Al.948Cr.052)2O3,(Al0.9Cr0.1)2O3,in which Al2O3 and TiO2 are the main phases.2.The inside of coating have a aluminum thermal reaction during Laser preparation of ceramic coating,the release of a certain amount of heat,as part of the mobile heat source.The Gaussian heat source moving model is written by using the APDL command flow in ANSYS software,and it is imported into the Workbench software to establish the geometric model.The temperature field and the stress field are simulated to obtain the distribution and size of the stress field.3.The temperature field of the multi-channel monolayer coating was simulated by ANSYS,and the temperature field distribution and the variation curve were analyzed at different time points.The results show:The temperature of the laser irradiation can rise to a very high temperature in a short time.As the number of laser steps increases,the initial maximum temperature is also increasing,the maximum temperature is 2700?,and the temperature suddenly decreases after scanning.The effects of preheating temperature,coating thickness and laser process parameters on the temperature field were studied.It was found that the proper preheating temperature could enhance the bonding property between the coating and the substrate.The coating thickness was0.1mm,The scanning speed has little effect on the temperature field.and the effect of laser power and spot diameter on the temperature field is obvious.4.Based on the simulation results of temperature field,the stress changes at the internal and interfacial layers under different service temperature and different process parameters were analyzed.The results show that the tensile stress at the interface is the compressive stress at the interface and the maximum stress is at the interface.With the increase of the service temperature,the stress at the interface decreases gradually.With the increase of the coating thickness,The stress state of the coating is not changed,but the stress state does not change.With the increase of the laser power,the residual stress increases slightly,but the stress state of the coating and the interface does not change.The spot diameter and laser scanning velocity have a better effect on the stress field Big.5.The temperature field and stress field of the sample were calculated by experimental method,It was found that the coated sample was brighter than the uncoated sample release because Al in the ceramic coating would undergo an aluminum thermal reaction,release a large amount of heat,heat applied to the coating It is equivalent to the laser heat source and aluminum heat reaction to release the heat superposition,thereby increasing the brightness. |
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