Research On The Preparation Of Amorphous Carbon Nitride And Its Friction And Wear Properties

Amorphous carbon nitride(a-CNx) films have many good properties, like high hardness value, very low friction coefficient, chemical inertness, and variable controllable electrical conductivity, etc. Thus, it is meaningful to carry out studies on a-CNx films for putting them into practical use.The main content of this paper can be divided into two parts, the first part is to study the absortption properties of different particles on the original substrate and growth surface, the second part is to fabricate different a-CNx films using radio frequency(RF) magnetron sputtering method and study their microstructures, content and properties via different measurements, the main conclusions are as follows:(1) The chemical adsorption simulation is conducted to study the absorption properties of N, N2 and CN clusters on the surface of silicon surface and graphite surface using Mater ial Studio software. The results show that N2 molecules are not absorbed by both surfaces, while N atoms and CN cluster can produce chemical adsorption on both surfaces, and N atom has strong adsorption capacity on both surfaces. It is concluded that it is of limited use just to increase nitrogen partial pressure in the deposition atmosphere to increase the nitrogen content in a-CNx film, it is better to improve the nitrogen gas ionization rate to generate more active N atoms.(2) Amorphous carbon nitride films are prepared under different nitrogen partial pressure, bias and substrate temperature using radio frequency(RF) magnetron sputtering method, the effects of these parameters on the structures, composition and mechanical properties of the films are studied. With the increase of nitrogen partial pressure, the surface roughness of the prepared films increases, a graphitization progress from sp3 bonds to sp2 bonds occurs, the N content shows a minor increase when the nitrogen partial pressure increase to 25%, and the film hardness, elastic modulus and internal stress decrease simultaneously. With the increase of substrate bias, the film surfaces are becoming dense and smooth, and the fraction of sp3 bonds increase first and then decrease, the hardness and elastic modulus have the same changing trend with the sp3 bonds fraction in the film. The film surface roughness decreases with the increasing substrate temperature, film graphitization and deterioration of mechanical property can occur at high substrate temperature, the optimized substrate bias and temperature are-50 V and 150 ℃, respectively.(3) The friction and wear properties of the prepared films are studied, the results show that a-CNx films prepared at high nitrogen partial pressure exhibit higher friction coefficient and wear rate than that prepared at low nitrogen partial pressure.With the increase of substrate temperature, the friction coefficient and wear rate decrease. As the load increases, the friction coefficient and wear rate decrease, but while the load is too high, the films can be worn out quickly. The friction coefficient and wear rate also show a decrease with the increase of sliding speed.