Study On Microstructure And Properties Of Laser Cladding On Aluminum Alloy Surface

1050 aluminum alloy has high plasticity and machinability,but its hardness is low and wear resistance is poor.How to improve its surface properties and make its application more extensive is worth studying.High silicon aluminum alloy has many advantages,such as high specific strength,low thermal expansion coefficient and excellent wear resistance.It is widely used in automobile,ship,aerospace,electronic packaging and other fields.However,it is difficult to obtain super high silicon content in high silicon aluminum alloy by traditional casting method,and the internal structure is coarse and the mechanical properties are poor.Other production technologies,such as spray deposition technology and powder metallurgy technology,have high production costs and complex processes.It is of great practical value to find out a preparation method of high silicon aluminum alloy with low production costs and simple processes.Laser cladding technology is developing rapidly in recent years.It can be used to improve the surface properties of materials,as well as to prepare new materials which has bright prospects.In this paper,the laser cladding technology is used to prepare a high silicon aluminum cladding layer on 1050 aluminum alloy using the LWS-1000 Nd:YAG laser.The surface properties of 1050 aluminum alloy were improved by laser cladding of pure silicon powder.Al-70Si and Al-Si gradient materials were prepared by multi-layer cladding of aluminum powder and silicon powder.The experimental results show that laser power,laser scanning speed and preset powder thickness have a great influence on the quality of cladding layer.The three parameters are matched in a certain range.The optimum parameters obtained in experiments are laser power170W,laser scanning speed 200 mm/min and preset powder thickness 250 um.The high silicon aluminum cladding layer was successfully prepared on the surface of1050 aluminum alloy.The content of silicon is about 68.5%,the hardness is 245 HV,which is about 210 HV higher than that of the matrix.The wear resistance is also improved,and 1.1 mg lower than that of the matrix.The addition of rare earth oxide Y₂O₃can improve the wettability of aluminum powder and the spheroidization phenomenon in laser cladding.Al-70Si was successfully prepared by Multi-layer laser cladding with the mass ratio of aluminum powder to silicon powder(3:7)and 2%Y₂O₃content.The hardness is about 245HV,the tensile strength about 85MPa,elongation about 1.5%,and the thermal conductivity at room temperature is about 56W/(m?K).After holding for 4 hours at 500?,the tips of long primary silicon are passivated,and the hardness increases by about 50 HV,and the thermal conductivity increases by 11 W/(m?K).Aluminum-silicon gradient materials with increasing silicon content from 70%to nearly 100%were prepared by controlling the ratio of silicon powder to aluminum powder in each layer.From the top surface to the interface,the hardness decreases gradually from 600 HV to about 200 HV.