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Hard Corrosion and Radiation-Resistant Coatings

#3929


Hard Nano-Strutural Coatings Resistant to the Extreme Conditions of Chemical, Abrasive and High Energy Media for Thermonuclear Power, Oil and Gas and Chemical Industries

Tech Area / Field

  • MAT-SYN/Materials Synthesis and Processing/Materials

Status
3 Approved without Funding

Registration date
22.12.2008

Leading Institute
A.N.Frumkin Institute of Physical Chemistry and Electrochemistry, Russia, Moscow

Collaborators

  • Hardide Limited, UK, Bicester

Project summary

The project focuses on the investigation of new nano-structured hard coatings which prevent abrasive, corrosive and erosive wear of metal constructions. These hard coatings when applied in industry will ensure environmentally-clean and un-interrupted operation of units and mechanisms in chemical, petro-chemical and upstream oil-and gas industries. The main aspect of the project will be the studies of the deposition processes of these new super-hard and tough coatings suitable for operation in chemically-aggressive and abrasive media and investigation of their corrosion-resistance. The problem resolve of radiation-resistant protective layers based on these coatings for high-temperature thermonuclear power installations, including installations with high-temperature liquid metal coolants, could help improving their safety and reliability.

The study of the corrosion-resistance of two new classes of nano-structured construction and functional coatings based on tungsten carbide compositions in contact with liquid metal heat-carriers, acids, H2S solutions and other aggressive media will be among the first tasks of the proposed project. The first class of coatings includes super-hard nano-crystalline tungsten carbides. The key requirements to these coatings are: high density (absolutely pore-free coatings); sufficient thickness (12-25 microns); necessary hardness (above 30 GPa); strong adhesion to construction materials (above 150 MPa); enhanced mechanical properties of the coating material. The second class of coatings includes the nano-composite mixtures based on tungsten carbides possessed by high toughness and necessary controlled hardness (10-21 ± 1,5 MPa). The proposed project concept of building nano-composite structures in thick hard films is a pioneering concept from both theoretical and applied perspectives. Both classes of coating are absolutely pore-free, that is essential for their corrosion-resistance. It is necessary to point out that hard pore-free coatings which can be produced at low temperature on complex shape items are novel for the world industries.


On the other hand Tungsten and Tungsten Carbide compositions create an excellent barrier for the diffusion of Hydrogen isotopes, that makes them most attractive for applications in the thermonuclear reactors. The functional coatings for these applications must have good radiation-stability, high heat-resistance, good heat conductivity, resistance to thermal cycling, good corrosion-resistance and high density (be absolutely pore-free) and have sufficient thickness (between 12 and 3000 microns). At present Tungsten and Tungsten carbide compositions are considered as most perspective for some of the most responsible units of the thermonuclear reactors.


Purpose of the project: comparative tests and analysis of the corrosion-resistance of pore-free W and W-C coatings with nano-crystalline and nano-composite structure (presented in this project), as well as other hard wear-resistant coatings and functional materials currently used in the industry, in various aggressive media: inorganic acids, seawater, H2S solutions, liquid Lithium. The recommendations for the industrial applications will be prepared on the basis of these comparative tests.


The main task of the project is to select most perspective compositions based on Tungsten and Tungsten Carbides and perform comparative analysis of their performance in the corrosive media listed above. It is intended to develop scientific foundations of the gas-phase synthesis of the necessary nano-crystalline structures based on Tungsten Carbides using thermodynamics approach and the theory of the chemical vapour crystallisation of inorganic materials developed by the authors of the proposed project. The investigation and understanding of the nano-effects of the mechanical characteristics of the nano-composite coatings will represent a substantial novelty of this project. Both theoretical and experimental analysis of the corrosion resistance of both existing protective coatings and new materials based on Tungsten and Tungsten Carbides will be conducted. A necessary part of the project will be the development and production of the pilot installation for the deposition of coatings based on Tungsten Carbides which can be used in harsh conditions of radiation, abrasive, erosive and corrosive wear. The pilot installation is necessary to conduct further R&D works to investigate the deposition processes of hard and super-hard coatings based on Tungsten Carbides and for preparation of practical recommendations for various sectors of industry, including precision machine-building and power.


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