Temperature dependence of the extreme-pressure behavior of CuO and TiO₂ nanoparticle additives in metal-forming polymeric lubricants

Abstract

Purpose

The purpose of this work is to investigate the effect of temperature on the extreme-pressure (EP) properties of CuO and TiO₂ nanoparticle-filled polymeric lubricants for metal-forming processes.

Design/methodology/approach

This paper studies the effect of nanoparticle additives of CuO and TiO₂ on the load-carrying capacity of a metal-forming polymer lubricant used for deep-drawing at varying temperatures. EP measurements are performed with a four-ball tribotester according to the ITeE-PIB Polish method for testing lubricants under scuffing conditions. Tests are run at 25, 40, 60 and 75°C to further decrease the lubricant film thickness and determine the effect on the load-carrying capacity and the tribological mechanisms of nanoparticles. The tribological mechanisms of nanoparticles is studied using energy dispersive spectrometry (EDS).

Findings

Results indicate that nanoparticle additives increase the load-carrying capacity of the polymeric lubricant at all concentrations up to 60°C attributed to a mending effect and a reduction in the area of contact of moving surfaces; at 75°C, the improvement is lowered due to nanoparticle re-agglomeration. The best results are found with TiO₂ nanoparticles due to their smaller size compared to CuO.

Practical implications

Nanoparticles of CuO and TiO₂ are potential EP additives for metal-forming lubricants, providing protection to working components and extending tool life.

Originality/value

These results show the effectiveness and the tribological mechanisms of nanoparticle additives under EP conditions and increasing temperatures found in metal-forming processes.

Citation

Peña-Parás, L., García-Pineda, P., Maldonado-Cortés, D., Garza, G.T. and Taha-Tijerina, J. (2017), "Temperature dependence of the extreme-pressure behavior of CuO and TiO₂ nanoparticle additives in metal-forming polymeric lubricants", Industrial Lubrication and Tribology, Vol. 69 No. 5, pp. 730-737. https://doi.org/10.1108/ILT-02-2016-0023