PARTICOAT

New multipurpose coating systems based on novel particle technology for extreme environments at high temperatures

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 Obiettivo del progetto (Objective)

'The overall objective of the project is to develop a novel, unconventional and cost efficient type of multipurpose high temperature coating systems on the basis of property tailoring by particle size processing of metallic source materials. It shall possess multi-functionality that will comprise thermal barrier effect, oxidation and corrosion protection, lotus effect, electrical insulation at elevated temperatures and fire protection. The concept of the novel approach to protection of surfaces is a coating consisting in its initial state of nano- and/or micro-scaled metal particles with a defined size, deposited by spraying, brushing, dipping or sol-gel. During the heat treatment, the binder is expelled, bonding to the substrate surface achieved, the metallic particles sinter and oxidise completely resulting in hollow oxide spheres that form a quasi-foam structure. Simultaneously, a diffusion layer is formed below the coating serving as a corrosion protection layer and as a bond coat for the top layer. The structure of the coating system shall be adjusted by parameters like selection of source metal/alloy, particle size, substrate, binder and a defined heat treatment. For fire protection the formation of hollow oxide spheres will be processed in a separate step before deposition. The flexibility of the new coatings integrates a wide field of application areas, such as gas and steam turbines in electric power generation and aero-engines, combustion chambers, boilers, steam generators and super-heaters, waste incineration, fire protection of composite materials in construction as well as reactors in chemical and petrochemical industry. A broad impact will thus be ensured increasing safety and the durability of components by an economic, multifunctional and flexible protection of their surfaces. The novelty will provide a real step change in the understanding of materials degradation mechanisms in extreme environments.'

Introduzione (Teaser)

Particle processing improves coatings

Descrizione progetto (Article)

Gas and steam turbines for power generation, aero-engines, chemical reactors and construction materials all rely on thermal barrier coatings. They are widely used and the market potential for improved coatings with better performance at a lower cost is significant.

EU-funded scientists initiated the project http://www.particoat.eu (PARTICOAT) to produce a single coating combining features of high-temperature protection, fire protection and high-temperature electrical insulation. The team achieved all original goals set forth in the project proposal with a variety of coating solutions.

Researchers chose aluminium micro-particles in the range of 1 - 20 micrometres. They successfully bonded the particles to the substrate surface. The heat treatment used also helped create hollow oxide spheres from the original metallic particles to form a foam-structured topcoat. A diffusion layer was formed beneath the topcoat serving simultaneously as a bond coat for the topcoat as well as a corrosion protection layer.

Testing of high-temperature heat resistance of the aluminium-based coatings demonstrated reduction of temperature up to 25% with a top coat thickness of 170 micrometres. The coatings adhered well to the substrates and were also resistant to scratching. Investigators used oxidised aluminium micro-particles to produce an inner layer and other particles implanted in an outer flame-retardant layer for two different fire-protection coating solutions. They both passed flame resistance and heat protection tests and an industrial scale production procedure was defined for both.

Scientists developed three coating solutions for copper electrical conductors used in high-temperature heating elements. Having passed all tests for scratching, adhesion, erosion, flame-resistance and electrical resistivity, the concepts are proceeding to in-field testing.

PARTICOAT successfully demonstrated thermal barrier coating concepts in which a bond coat and topcoat system is formed in one thermal treatment step. The use of spherical aluminium particles enables the formation of the bond coat and their oxidation creates hollow spheres that act as a thermal barrier. These low-cost multi-functional coatings are already of interest to partners for use in pre-combustion components and thermocouple tubing.