Robust high-temperature macroscale superlubricity enabled by interface engineering of boronized surfaces and...

Superlubricity materials and technologies, which enable near-zero friction (COF < 0.01) and wear between sliding pairs, have the potential to reduce energy losses by more than 20% and cut CO₂ emissions by 290 million tons annually upon successful implementation. Current superlubricity is mainly achieved at room temperature using non-metallic materials, whereas industrial equipment components often operate over a wide temperature range, making existing systems insufficient for practical applications. In our study, we present an interface engineering strategy that employs a boronized layer combined with hydroxyl-rich polyol lubricants to achieve superlubricity from room temperature to above 200 °C. Our results demonstrate that the synergy between the in-situ formed passivation tribofilm at the interface and polyol lubricants rich in hydroxyl groups is critical for achieving superlubricity over a wide temperature range, and the temperature tolerance limit strongly depends on the number of -OH groups. Specifically, the superlubricity failure temperature increased from 100 (glycerol) to above 200 °C (polyglycerol-10) as the number of -OH groups increased. Molecular dynamics (MD) simulations indicated that the cohesive forces of the lubricants were enhanced by increasing the number of -OH groups, which form strong hydrogen bonds. This enhancement contributes to increasing the oil film thickness and improving the high-temperature tolerance limit of superlubricity. In a word, we demonstrate that the deliberate pairing of boronized interface engineering with hydroxyl-rich polyol lubricants delivers macroscale superlubricity across an unprecedented temperature span, while highlighting the pivotal influence of hydroxyl content in the lubricant. This advancement provides theoretical and technical support for the innovative material design and industrial-scale application of high-temperature superlubricity.