超音速火焰喷涂NiCrBSi涂层高温摩擦磨损性能研究

Tribological Behavior of HVOF-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、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（SEM）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、Cr?O?与NiCr?O?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2×10?? mm3/(N·m)升高至600 °C时的11.3×10?? 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 ℃时因涂层硬度显著下降而产生大量磨屑，磨粒磨损上升为主导机制。

Abstract:

A NiCrBSi coating was fabricated on 304 stainless steel substrate using high-velocity oxygen-fuel (HVOF) spraying. The friction and wear behaviors of the coating were systematically investigated at room temperature (RT), 200 °C, 400 °C, and 600 °C to reveal the influence 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 microscopy (SEM) and high-temperature microhardness testing, respectively. The morphology and chemical composition of the wear tracks were characterized using white light interferometry and Raman spectroscopy. The results indicate that the NiCrBSi coating exhibits a distinct crystallization exothermic peak at approximately 505 °C. Above this temperature, the crystallinity and microstructure of the coating were significantly improved. As the temperature increased, both the porosity and microhardness of the coating generally decreased, with a relatively gradual decline 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 induced oxidation during friction, generating oxides such as NiO, Cr?O?, and NiCr?O?. At temperatures below 505 °C, the high-temperature environment led to a certain reduction in the friction coefficient. With a further increase in temperature, the lubricating effect of the oxides further contributed to the decrease in the friction coefficient. Meanwhile, the wear rate of the coating continuously increased with temperature, rising from 2×10?? mm3/(N·m) at RT to 11.3×10?? mm3/(N·m) at 600 °C. At room temperature, the dominant wear mechanism was fatigue wear. As the temperature increased to 600 °C, the marked decrease in coating hardness led to the generation of substantial debris, making abrasive wear the predominant mechanism.