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Influence of external magnetic field on the tribological performance of magnetic fluids in different lubrication regimes
Friction
Published: 23 January 2025
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Magnetic fluids (MFs) represent a unique class of smart functional lubricating materials, with their physical properties tunable by the application of a magnetic field. In this study, stable MFs were prepared with varying mass fractions of Fe3O4 nanoparticles. The influence of magnetic field on their tribological behaviors was examined on a modified rotational rheometer in both boundary and mixed lubrication regimes. The results show that the magnetic field significantly enhances the tribological performance of the MFs, especially for boundary lubrication. In particular, for the MF containing 1 wt% Fe3O4 nanoparticles, a friction reduction of 41.2% and a wear volume reduction of 94.7% were achieved in the presence of a magnetic field. Post-analysis of the worn surfaces was carried out with multiple techniques to gain deeper insights into the lubrication mechanisms. In the boundary lubrication regime, the magnetic field aids in introducing a larger amount of Fe3O4 nanoparticles into the contact, leading to the formation of a more continuous deposit film.

Open Access Research Article Issue
Super wear-resistant WB4–B super-hard ceramic by in-situ formed lubrication film in high moisture
Journal of Advanced Ceramics 2024, 13(12): 1955-1964
Published: 28 December 2024
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Only a few materials demonstrate ultralow wear performance in specific fragile environments. We propose a self-adaptive wear strategy to achieve excellent wear resistance at high moisture contents through a super-hard substrate and an in situ lubrication layer. We prepare “self-adaptive” super wear-resistant WB4B ceramic with a wear rate of 1×10−7 mm3·N−1·m−1 in dry environments, which relies on the superhardness of WB4 and B dual phases to maintain microstructural stability. The wear rate decreases further to 1×10−8 mm3·N−1·m−1, accompanied by a low friction coefficient of approximately 0.1, due to the in situ H3BO3/WO3 lubrication film in the moist environment. In addition, this excellent wear resistance performance remains stable under a high contact stress of 2.81 GPa and long friction cycles of 1×105. The excellent wear resistance of WB4B ceramic, as well as their excellent adaptability under harsh conditions, improves component performance and reliability in environments that are often considered challenging for traditional materials.

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