Preparation, tribological behaviour and lubrication performances of nano‐CaWO₄:Eu³⁺ as EP additive in water‐soluble fluid for laminated copper cladding steel sheet during cold rolling

Abstract

CaWO 4: Eu 3+ nanoparticles in acidity (pH = 5) and alkalinity (pH = 10) solutions were prepared by citric acid method, and characterised by SEM and XRD. Tribological behaviour and lubrication performances of nano-CaWO 4 : Eu 3+ as extreme pressure (EP) additives in water-soluble fluid for laminated copper cladding steel sheet during cold rolling were studied. These results suggest that CaWO 4 :Eu 3+ exhibits excellent extreme pressure property, antiwear and antifriction performances in water-soluble fluid, especially when the optimal concentration was 0.3 wt%. The value of WSD reduced from 0.62 to 0.40 mm and the value of COF decreased from 0.078 to 0.068, the surface quality of rolled sheet is improved with the addition of nano-CaWO 4 :Eu 3+ (pH = 5 and pH = 10), because the tribofilm ($20 nm) composed of Fe 2 O 3 , WO 3 , Eu 2 O and CaO was formed on the worn surface to avoid direct contact between metal friction pairs in sliding process.