Microstructure And Properties Of Laser Cladding Ni-Al/Al₂O₃-13% TiO₂ Cermet Coatings And Numerical Simulation

As an important material surface modification technology,laser cladding can promote the metallurgical combination of the cladding layer and the surface of the substrate,occupying a pivotal position in the modern manufacturing industry.With the development of laser technology,cermet composite powder as a cladding material,while maintaining the excellent characteristics of metal while also having ceramic characteristics,has become a hot spot for laser cladding coating research and development.In this paper,Ni-Al/Al₂O₃-13%TiO₂ cermet powder was cladding on the surface of 45steel by laser cladding process to obtain a wear-resistant coating with both metal and ceramic properties.The structure,hardness,wear resistance and high temperature oxidation resistance of the cladding layer were studied,combined with the finite element numerical simulation to analyze the distribution characteristics of the temperature field and stress field in the coating,and corroborated with the experimental part to jointly interpret Ni-Al/Al₂O₃-13%TiO₂ cermet coating performance improvement factors and different process parameters affect the mechanism.The main research contents are as follows:1)In order to further study the hardness,wear resistance and high temperature oxidation resistance of Ni-Al/Al₂O₃-13%TiO₂ coating,the YLS-2000 fiber laser was used to prepare Ni-Al coating and Ni-Al/Al₂O₃-13%TiO₂ coating on 45 steel.The metallographic microscope,SEM,EDS spectrum analysis,X-ray diffraction and other systems were used to study the coating morphology,phase composition and element distribution.The HXD-1000TB Vickers hardness tester was used to measure the micro-hardness distribution of the coating cross section.The M-2000 wear test machine was used to conduct the wear test.The WS-G510 intelligent muffle furnace was used to test the high-temperature oxidation performance of the cladding layer and the substrate.The results show that,compared with Ni-Al coating,the macro forming quality of Ni-Al/Al₂O₃-13%TiO₂ coating is better,without cracks,the coating structure is more uniform and dense.The maximum hardness of the coating cross section is about twice that of the Ni-Al coating and about four times that of the substrate;The weight loss is about 1/2 of the Ni-Al coating,about 1/12 of the base material;the coating weight gain is relatively small compared to 45 steel.Therefore,the Ni-Al/Al₂O₃-13%TiO₂ coating is more uniform and dense,and its hardness,wear resistance and high temperature oxidation resistance are significantly improved compared to the Ni-Al coating and the matrix material.This study has certain reference significance for the analysis of the overall performance of cermet materials.2)Study the influence of laser power and scanning speed on the temperature field distribution of laser cladding Ni-Al/Al₂O₃-13%TiO₂ coating and Ni-Al coating.For single-pass laser cladding,ANSYS Workbench is used to simulate the temperature change of the cladding process.Through simulation parameter design,factor range analysis,using the dilution rate as a measurement indicator,combined with the analysis of the coating's macro-morphology quality,it is concluded that with the increase of laser power,the maximum temperature point of the coating gradually increases;with As the scanning speed increases,the highest point of the coating temperature gradually decreases;the laser power is the main factor affecting the temperature,and the scanning speed is the secondary factor affecting the temperature.When P=1200W and V=6mm/s,the obtained Ni-Al/Al₂O₃-13%TiO₂ coating has good macro-morphology quality,and the dilution rate is low at this time.3)The process parameters of laser cladding Ni-Al/Al₂O₃-13%TiO₂ coating with better quality were selected to analyze the temperature field and stress field of the laser cladding process under this parameter.Combined with the experiment and numerical simulation,the mechanism of the influence of temperature and stress on the coating structure and phase transformation was further studied.The results show that during the rapid melting and condensation of laser cladding,the surface structure of the cladding layer is relatively fine,and the structure gradually coarsens as the distance from the surface increases;Compared with Ni-Al coating,Ni-Al/Al₂O₃-13%TiO₂ has less tensile stress,which is also one of the factors that Ni-Al coating is prone to crack.