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Application of a new “green” sol-gel product using an original, versatile, accurate and in-line mixing device that improves the adhesion of paint on aeronautical sector products

European Union
Complete with results
Geo-spatial type
Total project cost
€281 629
EU Contribution
€197 936
Project Acronym
STRIA Roadmaps
Vehicle design and manufacturing (VDM)
Transport mode
Airborne icon
Transport policies
Societal/Economic issues,
Other specified
Transport sectors
Passenger transport,
Freight transport


Call for proposal
Link to CORDIS

GreenGELAIR aimed at developing a two component sol-gel product to be applied on spray or stick/brush device to improve paint adhesion on large surface for OEM or MRO situations.

It was done through:

  • Development of a new and competitive formulation of sol gel product based on hybrid organic-inorganic system. It will be competitive compared to commercial products regarding induction time, pot life and adhesion on surfaces.
  • Design of a versatile device capable of providing a wide and accurate range of sol gel on spray or stick/brush.

The Technological objectives are expected to surpass the performances existing in the market:

  • Sol gel product.
  • Reduce induction time below 30 minutes by means of promoters (acid, UV radiation, organometallics). Sonication will be integrated if necessary.
  • Increase the pot life beyond 12 h through optimal formulation with organopolysiloxane precursors.
  • Application device.
  • Accurate way to dose different components based on a gravimetric system instead of a volumetric one.
  • Design a versatile mixing system based on in-line mixing and recirculation. The system will produce the desired quantity and will be adaptable to spray or stick/brush application.
  • Design of an integrated cleaning system.
  • Evaluation of film.
  • Define a new testing methodology to evaluate film performances based on electrochemical controls (Electrochemical noise measurements (ENM), Electrochemical impedance spectroscopy (EIS) and Potentiodynamic Polarization Curves (PPC)).

The new sol gel product and the device designed was compared to conventional processes in complex shapes through a demonstration phase. OEM and MRO situations were considered, Brush and Stick applications were used in MROs scenarios and paint sprayer application was used in OEMs situations. Corrosion and adhesion tests were realised to obtain the comparative study of resulting films. Also, morphology and film thickness was controlled to ensure the adhesion of the film.


Parent Programmes
Institution Type
Public institution
Institution Name
European Commission
Type of funding
Public (EU)
Specific funding programme
JTI-CS - Joint Technology Initiatives - Clean Sky
Other Programme
JTI-CS-2013-1-ECO-01-070 Application of sol gel technologies on low weight green metallic fuselage section


Executive summary:

The GreenGELAIR project had been carried out between GALVATEC, an industrial SME working in surface treatments for the AERO sector and two leading RTD providers, UC3M with expertise in sol-gel processes and AIMME as a metal processing technological centre and leader of the consortium. GreenGELAIR project had developed an improved sol-gel coating with prolonged lifetimes and high corrosion resistance. Also a versatile, novel and accurate formulating and application device had been design and constructed.

Firstly a series of novel Sol-gel formulations were established and optimised at lab-scale. Induction time, pot-life and chemical structure were defined using FTIR, RMN, Viscosity values and TG/DSC in the case of study the thermal stability. Based on the characterisation data, the most adequate formulations for each application were proposed. In these conditions the corrosion resistance and adhesion properties were measured using EIS and pull-off test applying the sol-gel by means of a dip-coater device. The work followed with the optimisation of the processing to higher amounts, industrial surface treatment and curing conditions adapted for each spray, brush and stick application.

In this context, a novel, versatile, accurate and in-line formulating device was designed and constructed. This device had enabled us to formulate higher amounts of sol-gel product in an easy and reproducible way controlling the dosage, flow and the nature of the reagents. Cleaning and priming sequences had been defined in order to reproduce the optimal conditions in the device. The device was controlled using a programming sequence that takes into account the chemistry formulation.

The results indicated that the processing conditions such as surface treatment, application process and cure temperature play an important role in the final coating properties. In this way a new and effective physical-chemical characterisation methodology was developed to improve the quality of the sol-gel product. Viscosity, turbidity, pH and particle size analysis were studied and they defined the operational parameters in the sol-gel formulation process using the device.

The assessment of the coating had been carried out in test-pieces in AIMME facilities by means electrochemical techniques in terms of corrosion resistance using different application systems and from them, the optimal formulation and the optimal operational conditions have been selected.

Demonstration activities were performed by GALVATEC after establishing the optimal procedure to fabricate, treat the surface and apply sol-gel using different devices and painting systems in the AIMME facilities.

Afterwards pilot-scale trials following painting industrial procedures were conducted under the direction of GALVATEC employing the best performing formulations produced by the new device and managed by AIMME. Also, conventional pre-treatments such as TSA or Alodine were performed in GALVATEC in order to make the technical comparison with sol-gel coatings.

These sol-gel coated pieces and pieces coated by conventional pre-treatments were subjected to the final characterisation and performance tests according to the different standards for final product validation. Filiform corrosion, Salt Spray Chamber test, Dry/Wet adhesion, pull-off adhesion and electrochemical corrosion were carried out in OEM and MRO simulating situations for all pre-treatments studied (sol-gel and conventional).

Also, the results of the sol-gel coating were compared to those of other sol-gel products on the market that are currently used in the metal finishing industry.

As an outcome of the project, new improved low-VOC ecological coating materials with prolonged lifetimes, application protocols and formulating device were available for the MRO and OEM operations. Successful technical results had been obtained in terms of corrosion resistance and the formulation device would be ready to be implemented into a further scaled-up after carrying out the necessary capital investment on the part of the SMEs.


Lead Organisation
Asociacion De Investigacion De Las Industrias Metalmecanicas, Afines Y Conexas
Organisation website
EU Contribution
€111 725
Partner Organisations
Galvatec Sl
Organisation website
EU Contribution
€20 880
Universidad Carlos Iii De Madrid
Calle Madrid, 28903 Getafe (Madrid), Spain
Organisation website
EU Contribution
€65 331


Technology Theme
Manufacturing processes
Paint finishes for laminar flow
Development phase

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