The Structure Control And Evaluation Of Ni/Al₂O₃ Composite Coatings

Ni-Al₂O₃ composite materials are promising anti-wear and corrosion-resistant coating materials for their superior mechanical properties as well as high wear and corrosion resistance.Laser cladding has merits of high energy density,convenient operation,high speed in melting and solidification and is an important method to prepare Ni-Al₂O₃ composite coatings.In this thesis,a boehmite sol was used to prepare the preplaced coating and a CO₂ continuous laser cladding was used to prepare the Ni-Al₂O₃ coatings and the structure and properties of the coatings were analyzed and discussed as well.The main work includes:?1?AlOOH coated nickel powders was prepared to form Ni/Al₂O₃ composite powders.The preplaced coatings on the surface of titanium alloy were prepared using the composite powders.?2?Different process parameters of the laser cladding were tried to get better coatings.XRD,SEM and EPMA were used to test and analyze the coating structures,with which the optimum laser cladding parameters were found.?3?The hardness and wear-resistance of the Ni-Al₂O₃ coatings were tested and analysed.According to the research results,Ni-Al₂O₃ composite coatings with good mechanical performance were prepared successfully with the preplaced coating method and the laser cladding on the surface of titanium alloy.This study provides a valuable technical reference for the surface modification of titanium alloy.