Composite coatings using mixed alloy matrices reinforced with carbon-based solid lubricants as feedstock materials were prepared by atmospheric plasma spraying. The aim of the present study was to investigate the tribological characteristics of such coatings exploring potential benefits of CNTs as nano-additive to reduce friction and wear, improving lubrication conditions during operation in tribosystems, such as piston ring – cylinder liner systems. The chemical composition of feedstock materials and the thermal spray parameters during coatings deposition are correlated to friction coefficient and wear rate using pin-on-disk measurements. The developed coatings hybrid behaviour is studied. Co-based cermet as well as metal alloy anti-wear performance along with the promoted lubrication conditions during operation is revealed. The dependence of the developed coatings quality and performance on the characteristics of the feedstock powder is thoroughly discussed.

The study of self-lubricant coatings is a rapidly developing research field that is expected to address major issues arising from operation under high loads and thermal stresses of machine parts. It is of utmost importance that various critical tribological pairs such as crankshaft bearings, piston rings, etc. maintain their integrity, thus contributing to the engines efficient and reliable operation for long periods of time. Therefore, a choice of high-strength metals is required, with special treatments and/or coatings in combination with sufficient lubrication. In the present study, liquid lubricants encapsulated in poly(urea-formaldehyde) were incorporated in ceramic-metal matrices for the production of composite coatings by Atmospheric Plasma Spraying. Aspects concerning the survival of the capsules during their flight through the high temperature plasma flame, the maintenance of their integrity at impact with the substrate with high kinetic energy, their homogeneous dispersion within the coating mass, thermal spray deposition parameters adjustment and optimization are thoroughly discussed. Coating properties such as roughness, friction, adhesion strength, and wear behaviour were also investigated. Microstructural characteristics and friction-wear behaviour were found to be critical to the durability of coating.

In this study, solution precursor plasma spraying is used to produce LaAlO 3 perovskite topcoats for thermal barrier coating systems. LaAlO 3 solution precursors were prepared by in situ polymerization and were deposited under different conditions in order to determine the effect of spraying parameters on process yield, deposition rate, microstructure, and hardness. Preliminary results with deposition rates of 5-20 μm/pass and process yields in the range of 35-60% are presented. It is shown that low precursor solution feed rate, high plasma power, and medium atomization gas flow rate result in acceptable coating microstructure, although further optimization is needed to achieve adequate hardness.