# Synergistic Tribofilm Growth in Ethylene Glycol: A Dual-Additive Approach for Superior Lubrication

## TL;DR

This paper explores how two additives work together to create a special lubricating film in hydraulic fluid, greatly improving its performance under extreme conditions.

## Contribution

The study reveals a novel dual-additive approach for forming a synergistic tribofilm with enhanced lubrication properties.

## Key findings

- A bilayer tribofilm with a 6 nm PxOy-rich inner layer and a 140 nm amorphous carbon outer layer was formed.
- The tribofilm improved lubricity by 31%, wear resistance by 71%, and extreme-pressure load capacity by 577%.

## Abstract

This study provides an original insight into the synergistic mechanism through which TM-104 and Vanlube 672 facilitate the in situ formation of a nanoscale bilayer tribofilm in ethylene glycol-based hydraulic fluid. By optimizing the additive formulation to 0.5 wt.% TM-104 and 2.0 wt.% Vanlube 672, a structurally graded tribofilm was autonomously assembled at the friction interface, comprising a 6 nm-thick PxOy-rich inner layer and a 140 nm-thick amorphous carbon outer layer. This engineered interlayer delivers exceptional tribological enhancements, with a 31% improvement in lubricity, a 71% increase in wear resistance, and a remarkable 577% enhancement in extreme-pressure load capacity. The first discovery was that there were differences in the mechanisms between these two layers: the inner PxOy layer establishes strong chemisorption bonds with the substrate, while the outer carbon layer facilitates energy dissipation through shear-induced graphitization. These findings establish a new paradigm for designing multi-functional lubricant additives and provide a scientific basis for developing high-performance fire-resistant hydraulic fluids operable under extreme conditions.