Friction Dependence on Surface Roughness for Castor Oil Lubricated NiTi Alloy Sliding on Steel

Walters, Nicholas; Martini, Ashlie

doi:10.1080/10402004.2018.1520949

Cited by 5 publications

(2 citation statements)

References 8 publications

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“…Similar studies showed that, at low contact pressures, a 60NiTi pin and 52100 steel sliding contact lubricated by castor oil can exhibit ultra-low friction (friction coefficient of 0.008) Dong, 2013, 2014;Zeng et al, 2016). This result was later found to be strongly dependent on surface roughness, with the lowest friction only achievable with an average surface roughness of <20 nm (Walters and Martini, 2018). Experiments using a 60NiTi pin sliding on 52100 steel were carried out with poly-alpha-olefin (PAO) oil and showed that the lubricant decreased the friction coefficient from 0.6 to 0.1 (relative to dry sliding) and improved wear resistance (Zeng et al, 2012).…”

Section: Introductionmentioning

confidence: 69%

Grease Lubrication of Self-Mated 60NiTi Bearing Materials

2019

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60NiTi is an intermetallic alloy of nickel and titanium that exhibits a unique combination of properties, including hardness comparable to steel, almost twice the elasticity of steel, high corrosion resistance, and tensile strength comparable to ceramics. These properties are very desirable for bearing materials, especially those used in space applications where components must operate efficiently and reliably in harsh conditions. However, despite the fact that most bearings are grease lubricated, there has not been a systematic study of the tribo-performance of greases for 60NiTi lubrication. To address this, we compare the wear and friction of self-mated 60NiTi lubricated by different greases, including those currently used in space missions and general-purpose grease, in low speed sliding contacts. The results provide valuable information to guide selection of grease for 60NiTi contacts as well as lay the groundwork for possible development of new greases specifically for 60NiTi tribo-contacts.

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Section: Introductionmentioning

confidence: 69%

Grease Lubrication of Self-Mated 60NiTi Bearing Materials

2019

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“…where h is the film thickness, Ra ball is the average roughness of the ball, and Ra disk is the average roughness of the disk. Although the exact values of λ corresponding to transitions between lubrication regimes vary in the literature, they are often defined by λ 3 for full film lubrication, 1 λ 3 for mixed lubrication, and λ 1 for boundary lubrication [34,40,41]. However, these transition values are not absolute, and studies have shown that full film or mixed lubrication is possible even in cases where λ would typically suggest boundary lubrication (e.g., λ 1) [41].…”

Section: Lubrication Regime Analysismentioning

confidence: 99%

Effect of Temperature and Surface Roughness on the Tribological Behavior of Electric Motor Greases for Hybrid Bearing Materials

2021

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Greased bearings in electric motors (EMs) are subject to a wide range of operational requirements and corresponding micro-environments. Consequently, greases must function effectively in these conditions. Here, the tribological performance of four market-available EM greases was characterized by measuring friction and wear of silicon nitride sliding on hardened 52100 steel. The EM greases evaluated had similar viscosity grades but different combinations of polyurea or lithium thickener with mineral or synthetic base oil. Measurements were performed at a range of temperature and surface roughness conditions to capture behavior in multiple lubrication regimes. Results enabled direct comparison of market-available products across different application-relevant metrics, and the analysis methods developed can be used as a baseline for future studies of EM grease performance.

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Macroscopic Oil-Based Superlubricity Achieved on Steel Surfaces with the Roughness of Engineering Level

Yuan

Amann

et al. 2023

Tribol Lett

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Friction Dependence on Surface Roughness for Castor Oil Lubricated NiTi Alloy Sliding on Steel

Cited by 5 publications

References 8 publications

Grease Lubrication of Self-Mated 60NiTi Bearing Materials

Grease Lubrication of Self-Mated 60NiTi Bearing Materials

Effect of Temperature and Surface Roughness on the Tribological Behavior of Electric Motor Greases for Hybrid Bearing Materials

Macroscopic Oil-Based Superlubricity Achieved on Steel Surfaces with the Roughness of Engineering Level

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