超音速火焰喷涂NiCrBSi涂层高温摩擦磨损性能研究

Tribological Behavior of High-Velocity Oxygen-Fuel-Sprayed NiCrBSi Coatings at Elevated Temperatures

摘要:

采用超音速火焰喷涂技术在304不锈钢基体上制备了NiCrBSi涂层，系统考察了涂层在室温以及200、400和600 ℃条件下的摩擦磨损行为，旨在揭示高温对涂层磨损机制的影响规律。通过扫描电子显微镜和高温显微硬度计分别分析了温度对涂层微观结构和力学性能的作用机制，并借助白光干涉仪与拉曼光谱对磨痕形貌及其化学成分进行了表征。结果表明，NiCrBSi涂层在约505 ℃附近出现明显结晶放热峰，高于该温度后涂层结晶程度与微观结构得到显著优化。随着温度升高，涂层孔隙率与显微硬度总体呈下降趋势，在低于505 ℃时下降较为平缓，而超过该温度后降幅显著增大。摩擦过程中，涂层与对磨球间的机械作用及高温环境共同诱导氧化反应发生，生成NiO、Cr₂O₃与NiCr₂O₄等一系列氧化物。在温度低于505 ℃时，高温环境引起摩擦系数一定程度降低；随着温度进一步升高，氧化物所起的润滑作用进一步促使摩擦系数下降。与此同时，涂层磨损率随温度上升持续增大，由室温下的2.0×10^-5 mm³/(N·m)升高至600 ℃时的11.3×10^-5 mm³/(N·m)。室温条件下涂层的磨损机制主要表现为疲劳磨损；随着温度升高至600 ℃，因涂层硬度显著下降而产生大量磨屑，磨损机制转变为以磨粒磨损占据主导的复合磨损。在工程应用中，NiCrBSi涂层非晶转变温度的确定为涂层使用温度的设计和热处理工艺的制定提供重要的数据支撑。

Abstract:

A NiCrBSi coating was fabricated on 304 stainless steel substrate using high-velocity oxygen-fuel (HVOF) spraying. The tribological behavior of the coating was investigated at room temperature (RT), 200 °C, 400 °C, and 600 °C to reveal the effect of elevated temperatures on its wear mechanisms. The effects of temperature on the microstructure and mechanical properties of the coating were analyzed by scanning electron microscope and high-temperature microhardness tester, respectively. The morphology and chemical composition of the wear tracks were characterized using white light interferometer and Raman spectroscope. The results show that the NiCrBSi coating exhibits a distinct crystallization exothermic peak at approximately 505 °C. Above this temperature, the crystallinity and microstructure of the coating are significantly improved. As the temperature increases, both the porosity and microhardness of the coating generally decrease, with a relatively gentle decrease below 505 °C and a sharp drop beyond it. The combined effect of mechanical action between the coating and the counterpart ball and the high-temperature environment induces oxidation during friction, generating oxides such as NiO, Cr₂O₃, and NiCr₂O₄. At temperatures below 505 °C, the high-temperature environment leads to a certain reduction in friction coefficient. With a further increase in temperature, the lubricating effect of the oxides further contributes to the decrease in friction coefficient. Meanwhile, the wear rate of the coating continuously increases with temperature, rising from 2.0×10^-5 mm³/(N·m) at RT to 11.3×10^-5 mm³/(N·m) at 600 °C. At RT, the dominant wear mechanism is fatigue wear. As the temperature increases to 600 °C, the marked decrease in coating microhardness leads to the generation of substantial debris, making abrasive wear the predominant mechanism. In engineering applications, the determination of the amorphous transition temperature of NiCrBSi coatings provides essential data for the design of coating service temperatures and the formulation of heat treatment processes.