Preparation And Properties Of Laser Cladding Cu-Ti-Zr Based Amorphous Composite Coating

Amorphous alloy materials have a special glassy structure,so they have high strength,high hardness,and excellent wear resistance.Pure Cu has exceptional electrical and thermal conductivity,but its hardness is relatively low and its wear resistance is poor.In this paper,the composite material is obtained by preparing an amorphous composite coating on the surface of pure Cu,which can comprehensively utilize the high electrical conductivity and thermal conductivity of Cu and the high strength and abrasion resistance of amorphous,which greatly broadens the application field of Cu materials.In this paper,two kinds of amorphous systems,Cu₄₇Ti₃₀Zr₈Ni₇Hf₈ and Cu₂₅Ti₇Zr₅₂Ni₉Al₇,are selected.Metal powders are prepared by arc smelting and vibration milling,and laser cladding experiments are performed on pure Cu surfaces by coaxial powder feeding.Analyze the phase composition,microstructure and mechanical properties of the coating under different process parameters to optimize the best process parameters,and then test the coating's resistance to electrical ablation and friction and wear.The main results are as follows:1.The laser power density and scanning speed of the Cu-Ti-Zr-Ni-Hf based amorphous coating are optimized.The Cu-Ti-Zr-Ni-Hf based amorphous composite coating mainly includes amorphous,pure Ti,HfO₂ and Cu₄Ti phases.The coating is firmly bonded to the substrate.The interface region is mostly a crystalline phase,while the surface region is a crystalline phase dispersed on the amorphous substrate.The interface between the phases is pure.The key conditions affecting the obtaining of the amorphous phase are the cooling rate and chemical composition.2.A suitable laser power density and scanning speed were selected to prepare a Cu-Ti-Zr-Ni-Al amorphous composite coating.The coating contains an amorphous phase,a ZrCu phase,a Cu₁₀Zr₇ phase,and a small amount of Al_2.5Cu_0.5Zr phase.The coating and the substrate are diluted and miscible.The interface area is mainly dendritic structure,and the surface area is fine equiaxed and amorphous.The interface between the two is clean and free of impurities.The microhardness change of the coating is consistent with the microstructure change.3.As the current value gradually increased,pores,cracks and pits appeared on the surfaces of the two amorphous coatings.The Cu-Ti-Zr-Ni-Hf amorphous composite coating is more resistant to electrical ablation than the Cu-Ti-Zr-Ni-Al.The increase of the load in the friction and wear experiment will aggravate the contact adhesive force.The form of wear is the mutual coupling between abrasive wear,adhesive wear and oxidative wear.In the friction and wear experiment,the increase of speed will increase the frictional heat,and the oxidation reaction will bring about the change of the wear mechanism.When the current is applied,arc ablation is the main failure mode,and the arc burned by the enhanced current is more serious.