Design,Fabrication And Properties Of (Cu₄₃Zr₄₇Al₇Ag₃)_99.5Co_0.5Amorphous Composite Coatings

Copper alloy materials are widely used in key parts of marine equipment.The harsh and complex service environment leads to the inevitable multiple damage problems of copper alloys in varying degrees such as wear,erosion and corrosion.Therefore,the development of protection and remanufacturing technology for copper alloy surfaces is of great scientific significance and engineering value.This paper used microalloying and molecular dynamics simulations to optimize the composition design of Cu Zr-based amorphous material systems.Cu Zr-based amorphous powders were prepared by vacuum aerosol method,and revealed the evolution of its microstructure.Modeled powder thermal mass transport and particle/substrate collision under low-temperature supersonic flame spraying technology by means of finite element simulation;explored the formation mechanism and optimal coating process of Cu Zr-based amorphous composite coatings under different coating temperatures;prepared high-performance Cu Zr-based amorphous composite coatings by low temperature supersonic flame spraying technology;systematically analyzed the anti-corrosion,wear resistance and mechanical properties of Cu Zr-based amorphous composite coatings;emphatically explored the crystallization behavior and fracture failure mechanism of amorphous composite coatings after annealing treatment,which can provide a scientific basis of the application of Cu Zr-based amorphous composite coatings on copper alloy.The main findings of the study are as follows:（1）Optimal design of composition of the quinary Cu Zr-based amorphous materials.The amorphous formation ability of 20 kinds of(Cu_46-xZr₄₇Al₇Ag_x)_100-yCo_y（x=0,1,2,3,4;y=0,0.5,1,1.5）systems were systematically analyzed by molecular dynamics simulation method.The corresponding Cu Zr-based alloy samples were prepared by copper mold suction casting process method,separately.The elastic modulus,microhardness and fracture strength of each sample were systematically characterized.The alloys which Ag is added have a better ability to form amorphous crystals,and Co added alloys inhibit the formation of stable clusters to reduce the ability of the alloy to form amorphous.The five-membered Cu Zr-based amorphous system with the best performance was initially selected as(Cu₄₃Zr₄₇Al₇Ag₃)_99.5Co_0.5,which maximum fracture strength of 2044±56 MPa and plastic strain of 3.27±0.09%.It is possibly that large-size nanocrystalline B2-Cu Zr phase was formed in situ inside the gold in the process of deformation,which hinders the propagation of shear bands.（2）Optimization of(Cu₄₃Zr₄₇Al₇Ag₃)_99.5Co_0.5 amorphous powder vacuum atomization process and study of annealing crystallization behavior.The microscopic morphology,material composition,phase structure evolution,crystallization activation energy and cluster structure of(Cu₄₃Zr₄₇Al₇Ag₃)_99.5Co_0.5 powders prepared by different processes were systematically investigated by SEM,XRD,TEM,DSC,XAFS and XPS analysis techniques.The rapid solidification mechanism of amorphous powder was summarized,the optimized process of amorphous powder vacuum atomization method was obtained.The crystallization behavior of(Cu₄₃Zr₄₇Al₇Ag₃)_99.5Co_0.5 amorphous powder at different annealing temperatures and holding times was analyzed to explore the feasibility of preparing amorphous composite coatings by low-temperature high-velocity air-fuel spraying.The analysis shows that the phase structure of amorphous powders will not change under annealing conditions below 753 K and 10 min.（3）Optimization and performance evaluation of(Cu₄₃Zr₄₇Al₇Ag₃)_99.5Co_0.5 amorphous composite coating process.The effect of spraying temperature on the melting state of amorphous powder and the amorphous phase content of the coating during low-temperature high-velocity air-fuel spraying were analyzed.The optimal spraying temperature and critical speed of the sprayed particles were determined.(Cu₄₃Zr₄₇Al₇Ag₃)_99.5Co_0.5 amorphous composite coatings were prepared by low temperature high-velocity air-fuel spraying technology at different spraying temperatures.The microscopic morphology,phase structure composition,bond strength and microhardness,friction and wear properties,corrosion resistance and overall mechanical properties of the coatings were systematically characterized.The crystallization behavior and fracture failure mechanism of amorphous composite coatings at different annealing temperatures and holding times were further analyzed.The analysis shows that the amorphous composite coatings prepared by spraying at 725K have high amorphous content（～67.5 wt.%）,low porosity（1.65%）,high hardness(554 HV_0.1),excellent wear and corrosion resistance,which fracture failure strain was0.78%and fracture strength was 620.3 MPa.The optimized process for the preparation of(Cu₄₃Zr₄₇Al₇Ag₃)_99.5Co_0.5 amorphous composite coating by low-temperature supersonic flame spraying was finally obtained.The core components of marine equipment copper alloy surface protection and repair were provided with an important scientific basis.