Investigation Into Coating Structure and Wear Environment Effects on Tribological Properties of Piston Ring Coated With Monolayer TiAlN and Multilayer TiN/TiAlN

Abstract

Friction among different engine components in internal combustion engines affects the life and combustion performance of the engine. Today, different surface coatings are made to reduce these effects. The physical vapor deposition (PVD) method has attracted the most attention because it is environmentally friendly and homogeneous coatings can be obtained. In this paper, tribological and mechanical properties of the monolayer TiAlN (titanium aluminum nitride) and multilayer TiN/TiAlN ceramic coatings applied to the piston rings made of cast iron with PVD method have been reported. In addition, the tribological behavior of the multilayer TiAlN coating was investigated for lubrication and dry conditions. The coating types, wear morphologies, chemical composition and phases on the coating surface were analyzed by SEM, EDS and XRD techniques. As a result of the tribological test, the coefficients of friction of mono- and multilayer TiAlN coatings under dry conditions were determined as 0.60 and 0.45 for 250 m, respectively. According to the result of the tribological test under lubricated environment conditions performed using the same parameters, it was determined that the friction of the multilayer TiAlN coating decreased by 85% (mu = 0.088). As a result, the multilayer TiAlN coated ring showed the best abrasion resistance. The reciprocating sliding test result showed that the wear rate of the multilayer TiAlN coating has been reduced by 95% compared to the uncoated ring. Considering all the experimental findings, it has been proven that as the number of layers in the coating increases, the surface roughness, hardness and wear properties improve. Furthermore, the wear mechanism was suggested to coated specimens based on the SEM image taken from the worn surface of the sample and EDX analysis.