Passivation Research Joint Laboratory – OxyMore

Passivation of alloys is a crucial phenomenon for corrosion protection. This phenomenon is based on the formation of a thin oxide film either : - spontaneously, called passive film, - by chemical or electrochemical treatments. The best known of these treatments is the anodisation of aluminium alloys.
This passive film is an oxyhydroxide, a few nanometres thick. It reduces the corrosion rate by several orders of magnitude. An alloy is considered stainless when its corrosion rate is less than 10 µm/year.
Chimimeca develops decontamination and passivation treatments for metal parts intended for the nuclear industry. It is also recognised in the aeronautics, naval and metallurgy sectors, etc.
These treatments are mainly based on hydrofluoric acid (for pickling) and nitric acid (for repassivation). Given the restrictions linked to their toxicity, Chimimeca is developing new formulations based on citric acid and wishes to undertake a scientific approach to demonstrate the effectiveness of these baths. This approach to the academic world aims to rationalise the design of the baths. The ultimate objective is to validate the developments with a scientific guarantee recognised in the world of surface engineering in order to give credibility to the effectiveness of more eco-responsible treatments that have been evaluated until now on the basis of standard tests. It is also a question of strengthening the chimimeca research team through training through research.
Therefore, a joint lab with MATEIS UMR 5510 CNRS/INSA Lyon/UCB Lyon1, represented by its Corrosion and Surface Engineering team (CorrIS) is envisaged. Exchanges were initiated during the confinement, and have taken concrete form in experimental collaborations within the framework of expert appraisals during the year 2021.
MATEIS devotes part of its work to the study of metal passivation. It has international recognition on the subject and participates in collaborations with major nuclear companies (EDF, Framatome, CEA, etc.). The convergence of views between the scientific and technical approaches, the degree of trust between the different actors of this collaboration and the various testimonies of encouragement from several of Chimimeca's customers, encouraged MATEIS and the company to create a joint laboratory.
Thus, by bringing together the scientific research of MATEIS and the industrial objectives of Chimimeca, the OxyMore Joint Laboratory will allow the development of innovative solutions for the reinforcement of the physicochemical properties of surfaces in relation to aggressive environments. Within the framework of OxyMore, both parties will focus on the characterisation and optimisation of the citric acid baths referenced PROCIV ECO5+ and PROCIV ECO7+, a new generation of passivation products for stainless steels. Although these baths are completely compatible from an environmental point of view, they are not yet included in the AFCEN's rules for the design and construction of mechanical equipment for high-temperature, experimental and melting nuclear installations (RCC-MRx). The aim is to provide the scientific and technical arguments that will enable this to be done.
The collaboration will be based on the expertise and the passivation characterisation approach developed by CorrIS. The approach is based on multi-scale characterisation of the physicochemistry of surfaces by XPS, AFM, SEM and TEM analyses (conventional and environmental) and electrochemical measurements (conventional or transient), both macroscopic and local, all of which are available in the laboratory. It will be possible to envisage, if necessary, targeted collaborations with other research teams on techniques that are not available. The perpetuation of OxyMore will be envisaged on the basis of the contributions of the project.