Abstract:The NiCrBSi-CrSi2 composite coating was prepared by supersonic flame spraying (HVOF) technology on the 12CrMoVG substrate by using different kerosene flow rates. XRD, SEM, EDS, Raman, Vickers microhardness tester, electronic tensile testing machine and high temperature rotational friction and wear testing machine were used to characterize the coating phase, microstructure, mechanical properties and high temperature friction and wear properties at different kerosene flow rates. The results showed that the phase composition of coatings is basically the same, all of which have γ-Ni, Ni3B, Cr2B, CrSi2 and Cr5Si3. But as the kerosene flow increases, the CrSi2 and Cr2B parts in the coating will be transformed into Cr5Si3 and CrB phases, respectively. The microhardness and bonding strength of the coating showed a trend of first increasing and then decreasing with the increase of kerosene flow, and the porosity and wear rate showed a trend of first decreasing and then increasing. When the kerosene flow rate is 30 L/h, the powder melting effect is the best, the porosity of the coating is as low as 0.17 %, the microhardness is higher to 569 HV0.3, the bonding strength is higher to 59 MPa, and the wear rate is as low as 2.84×10-14 m3/(N.m). Oxides such as Cr2O3, SiO2 and NiCr2O4 generated on the surface of the wear mark and the high coating hardness make the coating 30 L/h show optimal high temperature friction and wear resistance. The wear mechanism of the coating is mainly oxidative wear and adhesive wear.