Report

Teaser, summary, work performed and final results

Periodic Reporting for period 1 - Geo-Coat (Development of novel and cost effective corrosion resistant coatings for high temperature geothermal applications)

Teaser

Geo-Coat is an EU-funded collaborative project investigating newly developed coatings and Metal Matrix Composite bulk materials for use in high erosion and corrosion environments. Specifically, the project is focused on improving the lifetime of materials used in plants for...

Summary

Geo-Coat is an EU-funded collaborative project investigating newly developed coatings and Metal Matrix Composite bulk materials for use in high erosion and corrosion environments. Specifically, the project is focused on improving the lifetime of materials used in plants for geothermal energy production by the use of specialized coatings. These materials will also be applicable across a broad range of industry sectors including mining, construction, oil and gas, renewable energies production, food, etc. The Geo-Coat project has the following main objectives:

a) to capture, rationalise and model the design requirements for a range of geothermal components and environments spanning the European arena, based on the common degradation mechanisms experienced (i.e. corrosion, erosion and scaling);
b) to develop specialised corrosion- and erosion- resistant coatings, based on selected High Entropy Alloys (HEAs) and Ceramic/Metal mixtures (Cermets), to be applied through thermal powder deposition techniques (primarily high velocity oxy-fuel spray HVOF and Laser cladding) specifically tuned to provide the required bond strength, hardness and density for the challenging environments experienced in geothermal applications;
c) to develop improved models for efficient identification of optimal design requirements, modelling the chemistry and physics of corrosive and erosive forces at points along the process flow;
d) to develop a design Decision Support System (DSS) tool to produce reliable lifecycle estimates for performance, operational costs, environmental impact and risk. This tool will be developed with data from models and experimental database.

As a result of achieving these objectives, it is expected that the Geo-Coat technology could extend the lifetime and reliability of critical geothermal components. In this way, Geo-Coat will enhance the growth of geothermal energy, enabling the exploitation of aggressive geothermal fluid to generate electricity, while reducing
a) capital expenditure costs (Capex);
b) environmental impact during installation and
c) operational expenditure costs (Opex).

Work performed

The work performed so far focused on Stages 1, 2, 3 and 5, as specified by the red dashed line in Figure Simplified project plan for the Geo-Coat project and current status. The dimensions of each stage is not proportional to the time allocated to it. . Within Stage 1, in-depth literature research and chemical analysis of the geothermal fluid allowed the definition of the project’s Key Performance Indicators (KPI) and testing conditions for the testing Stages 3 and 4. Within Stage 2, manufacturing process parameters have been optimised for the coatings and MMC materials investigated. The optimised systems have then been tested for corrosion, tribological and scaling performance in simulated geothermal conditions within Stage 3, where two systems per substrate have been selected among all the ones tested. In parallel, the geothermal two-phase flow pipe network has been developed as the basis of the Flow Assurance Simulator (FAS). Specifically, the project has reached the following main achievements:
a) Identification of the state of the art in materials selection and common failures within geothermal power plants,
b) Characterization of the geothermal fluid at several locations within a geothermal power plant and definition of the test environment for the lab-based tests performed in the project,
c) Definition of the Key Performance Indicators (KPI) for the project,
d) Performed chemical equilibrium modelling of the geo-fluid,
e) Microstructural characterization and performance optimization of powders, consolidation process and consolidated bulk Metal Matrix Composite (MMC) materials by using both titanium and nickel based compositions,
f) Design and selection of High-Entropy Alloy powder compositions based on thermodynamic calculations to be used as powder materials for the coating deposition,
g) Microstructural characterization and performance optimization of powders and deposition process for High-Velocity Oxygen Fuel (HVOF) coatings based on HEA and cermet materials,
h) Microstructural characterization and performance optimization of powders and deposition process for Laser Clad coatings based on HEA materials,
i) Understanding and characterization of the effect of a variation in Laser Cladding deposition process parameters onto the melting of the substrate,
j) In-depth analysis of the effect of passive film formation onto the corrosion behaviour of HEA coating materials,
k) Microstructural characterization and performance analysis of powders and deposition process for Electrospark-deposited (ESD) coatings based on HEA materials,
l) Microstructural characterization and performance analysis of reagents and deposition process for Electroless Nickel Plated (ENP) duplex coatings of the Ni-P/Ni-P-PTFE class,
m) Development of cost and life cycle assessment (LCA) assessment for the coatings and MMCs produced in the project, employed in the project for ranking purposes,
n) Ranking of two coating and MMC systems per substrate/application based on a combination of corrosion, tribological and cost performance compared against state-of-the-art wrought alloys. The systems selected have shown, in most cases, an overall better performance compared to the wrought alloys.
o) In-depth study on the effect of the welding operation on the microstructural integrity of coated substrates,
p) Design and manufacture of the hardware required for testing of the down-selected systems in real and simulated geothermal conditions, and definition of testing environment based on the characterization of geothermal fluid,
q) Developed a geothermal two-phase flow pipe network as basis for the Flow Assurance Simulator (FAS).

Final results

Scientific knowledge has been expanded in many fields during the project, progressing the current research status. The progress made beyond the state-of-the-art by the project can be summarised in the main following points:
• Production and characterisation of high-entropy alloy powders by means of mechanical alloying, and understanding of the relationship between their microstructure and the microstructure of the deposited coatings,
• In-depth characterisation of the relationship between manufacturing process parameters and coating/MMC microstructure for all the technologies and materials tested in the project,
• In-depth understanding of the relationship between microstructure and corrosion and tribological performance for tests performed in simulated geothermal conditions,
• Characterisation of the effect of welding onto the integrity of coated components.
In addition, the following results and impacts are expected until the end of the project:
• In-depth understanding of the performance of the selected coatings/MMC materials in real geothermal environment,
• Understanding of the relationship between material performance in simulated versus real geothermal conditions,
• Demonstration of cost and environmental load reduction for all common geothermal power technology variants by using the Geo-Coat technology.

Website & more info

More info: http://www.geo-coat.eu/.