Gaseous Lubricity Additives for Hydrogen Gas

There is great interest in using hydrogen as a gaseous fuel in combustion engines to eliminate CO₂ emissions. Unfortunately, hydrogen gas is a poor lubricant for most engineering metals and an effective lubrication solution for pumping and injecting hydrogen is required. This study explores the possibility of additivating hydrogen with a low concentration of a lubricious gas to reduce friction and wear. We find that unsaturated hydrocarbon gas additives form protective carbon-based tribofilms, while gaseous ammonia and amine additives form nitrogen-based films on steel surfaces during rubbing in additivated hydrogen. Gaseous amines are particularly effective in reducing friction and wear, even at concentrations as low as 100 ppm mole/mole. This demonstrates that the addition of a small concentration of lubricious gas is a feasible way to improve the lubricity of gaseous hydrogen.