Effect of Humidity on Friction of Carbon Nitride Coatings Under N₂ Gas Lubrication Available to Purchase

The effect of humidity on friction properties of carbon nitride (CNx) in nitrogen (N₂) atmosphere were investigated by using a ball-on-disk tribo-tester in atmospheres with controlled humidity and oxygen concentration. It was concluded that friction coefficient in the combination of CNx/CNx and Si₃N₄/CNx in N₂ gas atmosphere were reduced from the order of 0.1 to 0.01 by decreasing of humidity from 40% RH to 0% RH when the O₂ concentration is kept below 100 ppm. Further, stability of low friction of CNx/CNx in N₂ gas atmosphere was confirmed experimentally. The frictional pair of CNx/CNx provided low and a stable friction coefficient of 0.01 in 99.9% nitrogen gas condition under low relative humidity of 2% or less.