HVOF喷涂CoCrWSi和Stellite-6涂层的结构与高温摩擦学性能研究

Microstructure and High-temperature Tribological Properties of HVOF Sprayed CoCrWSi and Stellite-6 Coatings

目的提高F92耐热钢基体在600、630℃下的高温耐磨性能。方法采用超音速火焰喷涂方法(High velocity oxy-fuel,HVOF)在F92表面制备CoCrWSi、Stellite-6两种涂层,利用扫描电子显微镜(Scanning electron microscope,SEM)和X射线衍射仪(X-ray diffraction,XRD)分析涂层的表面、截面形貌和物相组成,通过显微维氏硬度计(HV-1000STA)、高温摩擦磨损试验机(UMT-TRIBOLAB)、二维轮廓仪(TencorD-100)测定其显微硬度、高温摩擦学性能和磨痕体积。结果采用超音速火焰喷涂技术制备的CoCrWSi、Stellite-6两种涂层表面较平整,与基体结合紧密,内部组织均匀无裂纹,涂层的厚度约为200μm。XRD分析表明,CoCrWSi、Stellite-6涂层在室温下的物相都由γ(Co)、Cr_(7)C_(3)、CrSi_(2)组成。硬度及耐磨性能测试显示,CoCrWSi、Stellite-6涂层的维氏硬度相较于F92基体分别提高了3.12、2.68倍,F92耐热钢在600、630℃时的平均摩擦因数分别为0.87、0.86,体积磨损率分别为0.49×10^(-4)、1.11×10^(-4)mm^(3)/(N·m),其磨损机理主要为疲劳磨损、黏着磨损、氧化磨损。相较于基体,CoCrWSi涂层在2种温度下的平均摩擦因数分别降低了68%、71%,约为0.28、0.25,体积磨损率分别降低了约95%、97%,为0.20×10^(-5)、0.30×10^(-5)mm^(3)/(N·m),这主要归功于内部的Cr2O3、γ(Co)、Co_(3)O_(4)相在高温摩擦过程中具有良好的润滑效果。Stellite-6涂层也能在一定程度上改善基体的高温耐磨性能,其平均摩擦因数为0.85、0.71,体积磨损率为0.32×10^(-4)、0.57×10^(-4)mm^(3)/(N·m)。2种涂层的主要磨损机理均为磨粒磨损和黏着磨损。结论采用超音速火焰喷涂制备的CoCrWSi、Stellite-6涂层可以改善F92耐热钢在600、630℃下的耐高温滑动磨损性能,且CoCrWSi涂层的防护效果更佳。

To enhance the high-temperature wear resistance of F92 heat-resistant steel at 600℃and 630℃,two kinds of CoCrWSi and Stellite-6 coatings were fabricated via high-velocity oxy-fuel(HVOF)spraying.The surface and cross-sectional characteristics,as well as the phase composition of the coatings,were examined by scanning electron microscopy(SEM)and X-ray diffraction(XRD).Micro-hardness measurements were conducted with a Microvickers hardness tester(HV-1000STA).The tribological properties and volumetric wear rates were evaluated with a high-temperature tribotester(UMT-TRIBOLAB)and a two-dimensional profilometer(TencorD-100),with wear morphology and phase analysis performed by SEM and XRD.The SEM revealed that both coatings were well-adhered to the substrate,with smooth surfaces,uniform internal structures,and no cracks,averaging a thickness of approximately 200μm.XRD identified the main phases of the coatings as Co,Cr_(7)C_(3),and CrSi_(2)at room temperature.The presence of Cr_(7)C_(3)and CrSi_(2)phases in both coatings contributed to increasing hardness and wear resistance.The Co phase served as a lubricant,reducing the wear rate during sliding.Hardness and wear resistance tests indicated that the Vickers hardness of the CoCrWSi and Stellite-6 coatings were 3.12 and 2.68 times greater than that of the F92 substrate,respectively.The average friction coefficients for the F92 steel at 600℃and 630℃were 0.87 and 0.86,with corresponding volumetric wear rates of 0.49×10^(-4)mm^(3)/(N·m)and 1.11×10^(-4)mm^(3)/(N·m).The primary wear mechanisms for the F92 matrix were identified as fatigue,adhesive,and oxidation wear.Compared with the substrate,the CoCrWSi coating demonstrated a significant reduction in friction coefficients(68%and 71%)at two temperatures,which were about 0.28 and 0.25,respectively.The volumetric wear rates were reduced by about 95%and 97%,which were 0.20×10^(-5)mm^(3)/(N·m)and 0.30×10^(-5)mm^(3)/(N·m),at both temperatures,respectively.This was mainly attributed to the lubricating effects of internal Cr2O3,γ(Co),and Co_(3)O_(4)phases.In contrast,the Stellite-6 coating exhibited a lesser improvement in wear resistance,with average friction coefficients of 0.85 and 0.71,and wear rates of 0.32×10^(-4)mm^(3)/(N·m)and 0.57×10^(-4)mm^(3)/(N·m).The Stellite-6 coating suffered from more severe wear,primarily adhesive wear,with substantial abrasive chip accumulation.The CoCrWSi coating showed minimal wear at 600℃AND 630℃,with wear mechanisms dominated by abrasion and adhesion.The research findings indicate that HVOF-applied Stellite-6 and CoCrWSi coatings significantly improve the tribological properties of F92 steel at elevated temperatures,with CoCrWSi offering superior protective performance.This work employs high-velocity oxy-fuel spraying technology to deposit CoCrW coatings infused with a minor amount of Si onto the surface of F92 heat-resistant steel.It also conducts a comparative investigation into the tribological behavior of the F92 heat-resistant steel substrate,CoCrWSi,and Stellite-6 coatings under simulated actual working temperatures(600℃and 630℃),analyzing the wear mechanisms involved.The objective of the findings is to supply substantiated data to enhance the knowledge base regarding the high-temperature durability of CoCrWSi coatings on F92 steel.