煤油流量对NiCrBSi-CrSi2涂层微观结构及高温磨损性能的影响

Effect of kerosene flow on microstructure and high temperature wear properties of NiCrBSi-CrSi2 coating

摘要:

在12CrMoVG基体上通过超音速火焰喷涂(HVOF)技术,分别采用不同煤油流量制备了NiCrBSi-CrSi₂复合涂层。利用 XRD、SEM、EDS、Raman、维氏显微硬度计、电子拉伸试验机和高温旋转式摩擦磨损试验机分别表征了不同煤油流量下涂层物相、组织结构、力学性能和高温摩擦磨损性能。结果表明: 不同煤油流量涂层的物相组成基本相同,均有γ-Ni、Ni₃B、Cr₂B、CrSi₂和Cr₅Si₃,但随着煤油流量升高,涂层中的CrSi₂和Cr₂B的部分会分别转变为Cr₅Si₃和CrB相。涂层显微硬度和结合强度随着煤油流量的升高均呈现先增后减的趋势,孔隙率和磨损率表现出先减后增的趋势。当煤油流量为30 L/h时,粉末熔融效果最好,涂层的孔隙率最低为0.17 %,显微硬度较高达到569 HV_0.3,结合强度较高为59 MPa,磨损率最低为2.84×10_-14 m₃^/(N.m)。磨痕表面产生的 Cr₂O₃、SiO₂和NiCr₂O₄等氧化物以及较高的涂层硬度使得30 L/h的涂层显示出最优的耐高温摩擦磨损性能。涂层的磨损机制以氧化磨损和黏着磨损为主。

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 HV_0.3, 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 Cr}₂O₃, 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.