煤油流量对HVOF喷涂FeCrMoSi-Ti3SiC2涂层高温摩擦磨损性能的影响OA北大核心CSTPCD

Titanium silicon carbon(Ti3SiC2)is a new ternary compound MAX phase with excellent properties of both metallic and ceramic materials and it is prone to form oxide film on the friction surface,which makes it show excellent tribological performance at high temperature.However,the phase decomposition of Ti3SiC2-based coating prepared by thermal spraying technology is easy to occur,which affects its performance and restricts its wide application in high temperature protection filed.The work aims to individually granulate Ti3SiC2 powder by spray granulation technique,and then investigate the effect of different kerosene flow rates on the coating phase structure and tribological properties at high temperature. Ti3SiC2 particles were ground by a vertical planetary ball mill and mixed with quantitative deionized water and binder to obtain Ti3SiC2 water-based slurry,and then spherical Ti3SiC2 powder was prepared by spray granulation technique.The 12CrMoV matrix square sample with the size of 20 mm×20 mm×5 mm was prepared by electric discharge wire cutting mechanism.Before spraying experiment,the matrix sample was roughened by sand blasting and cleaned by ultrasonic with alcohol.The composite coatings with kerosene flow rates of 26 L/h,28 L/h,30 L/h and 32 L/h were prepared on 12CrMoV matrix by supersonic flame spraying(HVOF)technology.The phase composition,microstructure of powder and coating were investigated with X-ray diffractometer(XRD),scanning electron microscope(SEM),energy spectrometer(EDS)and Raman spectrum.Vickers microhardness tester and high temperature friction wear testing machine were applied to test the mechanical properties and the tribological properties.Finally,the wear mechanism of the coating at 800℃was analyzed. The results indicated that the powder phase was mainly composed of Ti3SiC2,Fe-Cr and TiC.The coating phase was similar to that of the powder,but a new SiC phase appeared.With the increase of kerosene flow,the Ti3SiC2 phase was gradually decomposed.When the kerosene flow was 30 L/h and 32 L/h,the Ti3SiC2 phase in the coating was decomposed a lot.The average microhardness of K-26,K-28,K-30 and K-32 coatings was 359HV0.3,528HV0.3,548HV0.3 and 485HV0.3,the fracture toughness was 3.75,3.94,4.65 and 3.95 MPa·m1/2,and the mean friction coefficient was 0.48,0.45,0.59 and 0.52,respectively.The hardness,fracture toughness and average friction coefficient of the four coatings all increased firstly and then decreased with the increase of kerosene flow.The porosity of coatings K-26,K-28,K-30 and K-32 was 1.03,0.44,0.31 and 1.62,and the wear rates was 6.17×10-15,5.44×10-15,8.62×10-15 and 6.79×10-15 m3/(N·m),respectively.The porosity and wear rate of the four coatings decreased firstly and then increased with the increase of kerosene flow.In summary,when the kerosene flow rate was 28 L/h,the coating had higher MAX content,higher hardness and lower porosity,which ultimately resulted in the lowest coefficient of friction and wear rate. The K-28 coating retains a high content of MAX phase,and the oxides such as SiO2,TiO2 and Fe2O3 generated on the surface are evenly distributed on the surface of the wear scars and dual ball,effectively blocking the direct contact between the dual ball and the coating,which makes the coating show the most excellent tribological performance.