Beyond Traditional Coatings: A Review on Thermal-Sprayed Functional and Smart Coatings

Abstract

Thermal spraying has been present for over a century, being greatly refined and optimised during this time. It has become nowadays a reliable and cost-efficient method to deposit thick coatings with a wide variety of feedstock materials and substrates. Thermal sprayed coatings have been successfully applied in fields such as aerospace or electricity production, becoming an essential component of today's industry. To overpass the traditional capabilities of those coatings, new functionalities and coherent responses are being integrated, opening the field of functional and smart coatings. The aim of this paper is to present a comprehensive review of the Advantage has been taken of a beneficial phase transformation triggered by the correspondent event (such as a crack or the tribological interactions respectively) to promote self-healing.Another approach has been the release of an encapsulated component which effectively heals the coating or provides lubrication when required. All these exciting developments pave the way for the numerous applications that are to come in the next decade, making the field of thermal sprayed coatings a unique opportunity for research and development.

Prospects of Low-Pressure Cold Spray for Superhydrophobic Coatings

“…The coatings presented in the paper are characterized by an uneven thickness of up to a few silica particles, but final hydrophobicity is provided uniformly on the surface by the formation of multi-level roughness by a detachment of outer layer from the SiO 2 particles. Thus, the presented approach constitutes a simple and fast solution for the fabrication of functionalized coatings using LPCS including industrial potential and fundamental research character.Coatings 2019, 9, 829 2 of 21 heating capabilities and position of the heater, portability level, presence of additional systems for limiting the wear of nozzle or proper agglomeration assistance [2][3][4]. What all of them have in common is lacking in feedstock material melting [1][2][3][4][5], which is unique among other thermal spraying technologies.…”

“…Thus, the presented approach constitutes a simple and fast solution for the fabrication of functionalized coatings using LPCS including industrial potential and fundamental research character.Coatings 2019, 9, 829 2 of 21 heating capabilities and position of the heater, portability level, presence of additional systems for limiting the wear of nozzle or proper agglomeration assistance [2][3][4]. What all of them have in common is lacking in feedstock material melting [1][2][3][4][5], which is unique among other thermal spraying technologies. New variations of CS technique are introduced in order to expand the range of feedstock materials and substrates [2][3][4] and thus the range of applications.…”

“…What all of them have in common is lacking in feedstock material melting [1][2][3][4][5], which is unique among other thermal spraying technologies. New variations of CS technique are introduced in order to expand the range of feedstock materials and substrates [2][3][4] and thus the range of applications. Alongside this, the deposition sequence for composite coatings is often being discussed [6] and more and more frequently mathematical models are prepared to assist experimental data [7][8][9][10].…”

“…However, attempts to deposit conventional (hard and brittle) ceramics are still not common which is mainly caused by the lack of understanding of the bonding mechanism nature. An overview of the literature indicates the application of ceramic materials to be tempting due to the completely different features offered when compared to metals [2][3][4]. It is enough to name the aerospace industry and gas turbine market where low density, good corrosion resistance, and high strength at high temperatures are undoubtedly the main advantages of ceramic materials.…”

“…Functional coatings can interact with a number of specific chemical stimuli such as the presence of water, or physical stimuli such as temperature, magnetic field, or light. A distinct feature of the metal oxides is the strong dependence of their properties on crystal structure and stoichiometry and therefore the low-pressure cold spray method seems to be particularly predisposed to the production of such coatings [2,3]. The LPCS minimizing the heat input can preserve or guarantee the desired materials behaviour.…”