Tribological properties of alloyed TiSi-stainless steel carbide coatings deposited by reactive cathodic arc method

Abstract

Alloyed TiSi-stainless steel carbide coatings were deposited by cathodic arc method on Si (100) and C45 steel substrates, from TiSi alloy and stainless-steel cathodes in C2H2 atmosphere. Different compositions were obtained by modifying the C2H2 mass flow rate and the arc current at the stainless-steel cathode. The coatings were investigated for elemental and phase composition, chemical bonding state, crystalline structure, morphology, hardness, adhesion strength, friction and wear performance. The coatings were found to possess a composite structure consisting of crystalline metallic carbide and amorphous free carbon. For carbon content higher than 43 at. %, the coatings exhibited a poor crystallinity and a random texture. All deposited coatings showed compact cross-sectional morphologies. It has been shown that the friction and wear performance of the carbide coatings were strongly dependent on the carbon content, such as the overstoichiometric carbide coatings presented superior tribological characteristics compared to the understoichiometric coatings. Depending on the carbon content, different wear mechanisms were identified: adhesive and oxidative wear for the coatings with understoichiometric carbide coatings, while for the overstoichiometric ones the adhesive and polishing wear was evidenced. The coatings containing the highest carbon content of ~64 at. % provided the best wear resistance (wear rate of 1.1 × 10−6 mm3N−1m−1) and the lowest friction coefficient (0.15).