Cr-ZrC含量对激光熔覆铜基复合涂层组织结构与力学性能的影响OA

Copper and its alloys are widely utilized in aerospace(e.g.,rocket engine combustion chambers,nozzles)and marine engineering(e.g.,ship propeller blades)due to their exceptional thermal conductivity,electrical conductivity and corrosion resistance.However,their low surface hardness and poor wear resistance restrict applications under extreme conditions,making the fabrication of composite coatings to enhance friction and wear resistance of great engineering significance.Chromium(Cr)is highly valued in surface engineering for its high hardness,wear resistance,and corrosion resistance,while zirconium carbide(ZrC)is commonly chosen as a laser cladding material owing to its high melting point,hardness and structural stability in extreme high-temperature environments.The work aims to optimize coating composition for the synergistic improvement of hardness,wear resistance and plasticity,providing theoretical and technical support for surface strengthening of copper-based materials under extreme working conditions.Cu-x(16Cr-4ZrC)(x=1,2,3)composite coatings were prepared on pure copper surfaces via laser cladding with Cu,Cr and ZrC powder materials.The microstructure,grain orientation,grain size and proportions of low/high-angle grain boundaries were analyzed through X-ray diffraction(XRD),scanning electron microscopy(SEM),and electron backscatter diffraction(EBSD).Dynamic compression tests,nanoindentation,friction-wear tests and microhardness measurements were conducted to investigate the relationship between Cr-ZrC content and the microstructure and mechanical properties,systematically revealing the regulatory mechanism of Cr-ZrC content on the microstructure and mechanical properties of the coating.The results demonstrated that increasing Cr-ZrC content significantly improved the coating's microstructure and mechanical properties.As Cr-ZrC content increased,the composite coating's structure transitioned from discrete layers to a continuous distribution,with reduced porosity.ZrC phases segregated at the interface between Cr-rich phases and the substrate,forming interfacial strengthening.The crystal orientation strength decreased,the grain size was refined,the proportion of low-angle grain boundaries increased from 56%to 67%,and the dislocation density rose significantly,leading to a marked increase in microhardness and indentation hardness-improved by up to 4.5 times and 1.9 times compared to the substrate,respectively.However,the increased number of grain boundaries inhibited dislocation slip ability,resulting in decreased coating plasticity.In terms of tribological properties,the friction coefficient and wear volume decreased by up to 30%and 43%compared to the substrate,respectively.Dynamic mechanical property tests showed that the coating exhibited significant rate sensitivity and strain-rate strengthening effects,with yield strength and elastic modulus increasing with Cr-ZrC content.At a strain rate of 2 000 s-1,the peak strains of the three composite coatings were 0.137,0.129,and 0.118,and the plastic deformation segment strain lengths were 0.128,0.119,and 0.105,respectively.In conclusion,with the addition of Cr-ZrC,the mechanical properties and microstructure of the laser-cladded copper-based composite coatings are significantly improved.By comparing the properties of coatings with different Cr-ZrC contents,the Cu-32Cr-8ZrC coating is found to achieve an optimal balance between wear resistance improvement and plasticity retention,along with excellent wear resistance.This series of studies can provide important references for the strengthening and repair of critical components in aerospace,marine engineering,and other fields.