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

Hydrogenated-carbon nitride (CNx:H) films are prepared on ZrO2/Al2O3 ceramic substrate via the pyrolysis of ethylenediamine at 800-1000 °C. The microstructure of as-prepared CNx:H films has been analyzed, and their friction and wear behavior have been evaluated. Results show that nitrogen in as-prepared CNx: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 CC bonds in as-prepared CNx:H films. Besides, a small amount of N atoms in the crystal lattice of graphite is chemically bonded with C atoms to generate CNx compound, and the friction and wear behavior of CNx:H films on the composite ceramic substrate is closely related to their microstructure and chemical structure. Namely, CNx: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, CNx: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 CNx:H films and Al in ZrO2/Al2O3 composite ceramic substrate chemically react to form NAl bond, which contributes to increase the bonding strength between the films and the ceramic substrate thereby significantly improving wear resistance of the films.