Currently, surface treatments on metals are utilizing hexavalent chromium CrVI (anodizing, chromic etching, chromating ...) as primer of adhesion to the subsequent layers (paints generally) and as an anticorrosive protection for the treated metal as well, reason why CrVI is extensively used in the metal industry. However, CrVI is highly toxic, and classified as CMR (carcinogenic, mutagenic and reprotoxic). So it was decided to ban this product in the industries but it is still tolerated in specific Industries (Aeronautic, off-shore…) until 2017. In most of the current substitution treatments, the CrVI has been replaced by the CrIII, but this does not provide full satisfaction in particular as regards the adhesion of paints. The 'sol-gel' technology based on organic treatments could be an alternative. However, it has some drawbacks, such as the lifetime before application (max 48 hours) or the impossibility to be applied again on itself (in case of touch-up paint, for instance).
The MESTREL project is part of this framework. The MESTREL Project is based on the SEEP technology (Surface Electroinitiated Emulsion Polymerization) patented by the Academic partner (CEA). This technology is an organic surface treatment which does not suffer the aforementioned disadvantages of the "sol-gel". Its first implementation, in immersing the sample in an aqueous bath containing, at least, one diazonium salt, leads to a chemically grafted coating compatible with aviation standards for adhesion of paint. Based on this expertise, the challenge of the project is to develop a generic CrVI substitution treatment using the formation of an organic film, robust, with good primer adhesion properties of the metallic surface (first technological barrier) and anti-corrosion properties as well (second technological barrier). The MESTREL project aims to develop a process easy to be industrialized, inexpensive, simple to implement (without immersion step) via the usage of spray technologies (3rd technological barrier). These three themes will be conducted in parallel with the industrial objective to commercialize these processes 3-4 years after the end of the project.
The success of this joint laboratory will be ensured by the complementarity and the high level of expertise of the project partners:
- The Laboratory of Innovation in Chemistry of Surfaces and Nanosciences (LICSeN) CEA is specialized in surface functionalization of materials. This laboratory, internationally renowned, has a large experience in technology transfer to Industry and has developed and patented the SEEP technology. The Laboratory will bring its scientific expertise to serve the implementation of practical tests.
- PROTEC Industry has been created 60 years ago. It is an SME of 140 employees, leader in France in the surface treatment field and specialized processes. An R & D center was created in 2012 with the main objective to develop “green processes” in order to replace the current processes using CrVI and other CMR products. This Laboratory gets a large knowledge of the industrial surface treatment and experience in R&D will allow to fit perfectly with the needs of the clients.
Aeronautics is first interested in the methods developed within the joint laboratory. However, because the methods develop in the Project are not specific, they could be quickly adapted to other markets fields, such as transport (train, for example) and offshore (wind platforms).
Through the development of “green” processes with a short-term industry transfer, MESTREL will provide significant competitive advantages to the SME PROTEC Industry, which will enable it to expand its market in many application areas in France and abroad.
Monsieur Guy DENIAU (Laboratoire d’Innovation en Chimie des Surfaces et Nanosciences/UMR 3685 NIMBE)
The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.
DRF-IRAMIS-UMR 3685 NIMBE-LICSeN Laboratoire d’Innovation en Chimie des Surfaces et Nanosciences/UMR 3685 NIMBE
Help of the ANR 300,000 euros
Beginning and duration of the scientific project: September 2016 - 36 Months