The tremendous growth of nanotechnology in recent years has led to the development of innovative advanced structural composites as well as severe operating conditions resistant coatings. Graphene-based derivatives such as graphite, carbon nanotubes (CNT's) etc., have shown strong potential for use as reinforcements, due to their excellent mechanical, electrical, and thermal properties. Furthermore, the unique lubricious nature of these materials makes them ideal candidates as reinforcement particulates in the development of self-lubricating multicomponent coatings.
Thermal spray is a low-cost, well-established technique that enables the deposition of a wide range of materials such as cermets, alloys, ceramics or their mixtures on different types of surfaces in terms of chemical composition, size and geometry. Atmospheric Plasma Spraying is regularly used in industrial practice as the preferred deposition technique for coatings aiming to prolong the service life and/or the dimension restoration of different worn components by preventing different types of wear such as abrasion, sliding wear, corrosive wear, erosion and their combinations prohibiting at the same time operation in high friction conditions.
This work focuses on the development of novel composite coatings applied by plasma spraying of mixed powders using graphene-based reinforcement particulates on steel substrates. Issues related to the optimization of the processing parameters, the investigation of the structural and morphological characteristics, as well as the assessment of the tribological behavior and mechanical properties characterization of these hybrid coatings are analyzed. In detail, wear resistance, friction coefficient, Vickers microhardness as well as bonding strength of the deposited layers were measured and subsequently evaluated in relation to the microstructural homogeneity and dispersion uniformity of the developed coatings. As revealed by the results, the addition of graphene-based particulates in metals and/or cermets used as feedstock powders results in the formation of thermally sprayed self-lubricating functional tribofilms capable of reducing friction and wear phenomena in metallic parts operating in internal combustion engines.
This research has been co?financed by the European Regional Development Fund of the European Union and Greek national funds through the Operational Program Competitiveness, Entrepreneurship and Innovation, under the call RESEARCH – CREATE – INNOVATE (project code: T2EDK-01883).