Influence of calcination temperature on structure as well as friction and wear behavior of CN_x:H films on composite ceramic substrate

Hydrogenated-carbon nitride (CN_x:H) films are prepared on ZrO₂/Al₂O₃ ceramic substrate via the pyrolysis of ethylenediamine at 800–1000 °C. The microstructure of as-prepared CN_x:H films has been analyzed, and their friction and wear behavior have been evaluated. Results show that nitrogen in as-prepared CN_x:H films is incorporated into graphitic structure by substituting carbon positions. Increasing calcination temperature gives rise to a decrease of N/C ratio and an increase of relative intensity of C=C bonds in as-prepared CN_x:H films. Besides, a small amount of N atoms in the crystal lattice of graphite is chemically bonded with C atoms to generate CN_x compound, and the friction and wear behavior of CN_x:H films on the composite ceramic substrate is closely related to their microstructure and chemical structure. Namely, CN_x:H film sample obtained at 800 °C has the maximum N/C ratio of 0.13 but the poorest adhesion to composite ceramic substrate, while the one prepared at 950 °C has a lower N/C ratio and the highest adhesion to substrate. Moreover, CN_x:H films formed on composite ceramic substrates with different surface roughness have similar friction coefficient (about 0.20) but different antiwear life. Particularly, N in as-prepared CN_x:H films and Al in ZrO₂/Al₂O₃ composite ceramic substrate chemically react to form N-Al bond, which contributes to increase the bonding strength between the films and the ceramic substrate thereby significantly improving wear resistance of the films. - Highlights: • Nanocrystalline CN_x:H films on ceramic substrate via pyrolysis of ethylenediamine. • Some N atoms incorporated into the crystal lattice of graphite to form CN compound. • Nanocrystal CN_x:H film prepared at 950 °C has the best wear resistance