Ceramic TiC/a:C protective nanocomposite coatings: Structure and composition versus mechanical properties and tribology

Abstract

The relationship between the structure, elemental composition, mechanical and tribological properties of TiC/amorphous carbon (TiC/a:C) nanocomposite thin films was investigated. TiC/a:C thin film of different compositions were sputtered by DC magnetron sputtering at room temperature. In order to prepare the thin films with various morphology only the sputtering power of Ti source was modified besides constant power of C source. The elemental composition of the deposited films and structural investigations confirmed the inverse changes of the a:C and titanium carbide (TiC) phases. The thickness of the amorphous carbon matrix decreased from 10nm to 1–2nm simultaneously with the increasing Ti content from 6at% to 47at%. The highest hardness (H) of ~26GPa and modulus of elasticity (E) of ~220GPa with friction coefficient of 0.268 was observed in case of the film prepared at ~38at% Ti content which consisted of 4–10nm width TiC columns separated by 2–3nm thin a:C layers. The H3/E2 ratio was ~0.4GPa that predicts high resistance to plastic deformation of the TiC based nanocomposites beside excellent wear-resistant properties (H/E=0.12).