Research Of Preparation And Simulation Of Al/Ti Laser Cladded Coating On 7050 Aluminum Alloy

This paper presented a scientific basic research on preparation technology of Al/Ti/Cu protective cladding coating. Nanometer particles dispersion, cladding sample preparation and the simulation of laser cladding process had successfully solved.The major work done and the results obtained were as follows:Firstly, by investigating various dispersion behaviors of nanometer Ti C particles in deionized water, 1:1 water-ethanol mixture and pure ethanol, it was confirmed that the most suitable dispersion solvent for preparing nanometer Ti C suspension was deionized water. Based on the Fluent finite element software, the flow field simulation of ball-milling dispersion process was studied. The ball milling suspension technological parameter was obtained by the flow field simulation and experiment. In comparison of dispersion behavior of ultrasonic, ball milling, ultrasonic ball milling and ball milling ultrasonic suspension, high dispersion was obtained by the method of ball milling ultrasonic suspension.Secondly, based on the process of laser cladding 50at%Al-50at%Ti composite powder above 7050 Aluminum, using an orthogonal experiment, an optimized cladding coating was achieved with the laser power of 1.5k W, the scanning speed of 150mm/min and the defocusing amount of 50 mm using CO2 Laser System. Using Ytterbium Laser System, 12 different optimized composite cladding coating were achieved with the laser power of 2.0k W, the scanning speed of 600mm/min and the defocusing amount of 15 mm.Thirdly, to study the process of laser clad Al/Ti composite powder above 7050-T74 Aluminum, a three dimensional model was established, which can simulate the influence of parameters temperature field affected by laser power and scanning velocity, and the molten pool size, the temperature gradient, cooling rate and the shape control factor in the condition of different defocusing amount. Finally, the simulated results about both the grain size and the crystal microstructure of the molten pool are verified by the experiment study.Finally, using SEM, EDS, XRD and micro-hardness tester, morphology, microstructure and micro-hardness of the laser cladding coatings with 25at%Al-75at%Ti, 50at%Al-50at%Ti and 75at%Al-25at%Ti were respectively investigated. It was found that the best cladding coating organization and performance were obtained under the laser cladding coatings with 50at%Al-50at%Ti. Al/Ti/Cu laser cladding coatings were prepared. The influence of different contents of Cu particles on coating quality was investigated. The laser cladding coating with 10wt% Cu particles in the powder composition was the best. The laser cladding coatings with nanometer Ti C were respectively investigated...