Microstructure and Properties of Ultra-high-speed Laser Cladding Ni-cBN/(NiCoCr)94Al3Ti3 Coating
Titanium alloys have high strength,low density,and excellent corrosion resistance and are important alloy materials in the aerospace field;however,their weak surface wear resistance restricts their application and further improvement in the aviation industry to a certain extent.To improve the wear resistance of titanium alloy surfaces,the application scenarios and service life of titanium alloy parts should be expanded.The wear resistance of the high-entropy alloy coating was improved by particle-strengthening technology.After adding 0,5,10,15,and 20 wt.％Ni-coated with cBN particles to(NiCoCr)94Al3Ti3 alloy powder,ultra-high-speed laser cladding technology was used to prepare Ni-coated cBN particle-reinforced(NiCoCr)94Al3Ti3 wear-resistant coating on the TC11 matrix.The influence of the Ni-coated cBN particle content on the wear resistance of the coating was investigated using XRD,SEM,EDS,hardness,friction,and wear analyses.Phase analysis of the five coatings showed that the content of the Ni-coated cBN particles was greater than 15 wt.％,and the FCC phase summit of the high-entropy alloy was weakened,indicating that Ni-coated cBN particles can reduce the ductile phase in the coating.Scanning electron microscopy and energy spectrum analysis showed that the content of Ni-coated cBN increased,the Cr in the coating was polarized,the Cr-rich phase structure was a thin strip and constantly aggregated and grew,and the Cr-rich phase belonged to the hard phase,which is consistent with the phase analysis results.The increase in Ni-coated cBN particles leads to an increase in the hard phase inside the coating and a decrease in the toughness phase.The hardness values of five coatings were measured.The hardness curve of the Ni-CBN coating showed that the hardness of the coating top was higher and the hardness of the cross-sectional binding area was lower owing to the uneven distribution of the particles.The accumulation and growth of the Cr-rich hard phase in the coating indicated that the hardness of the coating increased.However,the truss effect of cBN accumulation weakened the compactness of the coating and promoted an increase in its porosity,which affected the test hardness of the coating.Therefore,the average microhardness test results of these five coatings showed an initial upward trend,followed by a downward trend with an increase in the Ni-coated cBN particles.When hard cBN particles were added to the coating,hard particle points appeared during wear,resulting in an increase in the roughness of the friction surface.Therefore,the friction factors of the five coatings showed an upward trend with an increase in the number of Ni-coated cBN particles,and the high hardness characteristics of cBN sustained most of the grinding force.The larger the number of cBN particles,the smaller the friction contact area between the grinding pair and the coating.Therefore,the wear amounts of the five coatings gradually decreased with increasing Ni-coated cBN particle content,and the wear resistance of the coatings gradually increased.Among the five wear-resistant coatings,the cBN coating with 15 wt.％Ni has the best overall performance.The adhesion between the coating and substrate is strong,as is the adhesion between the cBN particles and coating.The coating exhibited the highest average microhardness,reaching 1 024 HV0.5 with a friction factor of 0.534 and a wear volume of 0.017 mm3.The wear resistance of the coating is 2.8 times that of the cBN particle coating without the addition of Ni.The addition of Ni-coated cBN particles can improve the wear resistance of coatings and provide a reference for the research and application of cBN in wear-resistant coatings.
NETL
NSTL
万方数据
