Revêtements nanostructurés multifonctionnels : ANTI-adhésifs, inTACHables et durs. – ANTI-TACH

The development of non-stick cookware during the fifties has largely contributed to make every body's cooking habits evolve. Today, however, more and more consumers look (back) for hard cooking surfaces which resist well to their aggressive cleaning. With the objective of proposing to these consumers, more resistant cookware, the Tefal company searches for new technical solutions. The ANTI-TACH project (multi-functional nano-structured non-stick, stain resistant and hard coatings) aims to work out the best conditions for transition metal nitride coating depositions on cookware by PVD reactive magnetron sputtering processes. These coatings will have to be at the same time, easy to clean, anti-adhesive, stain-resistant, and extremely robust versus scratches. Though Tefal research team has developed coatings in an especially designed pilot machine, these coatings do not meet the necessary requirements (food and thermal stain resistance) which could guarantee a large sale success. The ANTI-TACH project brings together the knowledge and the experience of five partners in the complementary following domains: food chemistry, surface chemistry, physical chemistry analysis, surface optical characterisation, PVD processes and homogeneous alloy design for the production of sputtering targets. The project aims to approach the physical and chemical involved mechanisms, to infer the best corresponding sputtering processes and to produce these multifunctional complex coatings. Once this objective will be reached, the coatings will provide to Tefal company, a major technical lead enabling it to expect a significant sale growth on its markets. This project is born from numerous discussions and from several preliminary studies led in collaboration between the afore-mentioned partners. It is divided in three phases which will be conducted in parallel. • A study will be made by the food chemistry specialists with the objective of classifying the stains and bindings due to cooked food, according to their natures. The different physical and chemical processes involved in the staining and in the anti-sticking will then be described by the surface and interface specialists. • From these understandings, coating optimisation solutions will be put forward and implemented by the PVD process engineering specialists. It is already planned, as far as the nature of the coatings are concerned, to act on several parameters and in particular on the densification of the deposited materials (to minimize the volume diffusion process) and on the addition of new chemical elements (coating oxidation resistance increase and final coating colour control). • The proposed solutions will then be transferred and tested at the industrial pilot scale. The development at an industrial scale, of nano-structured coatings of complex composition requires precisely designed sputtering targets. This is the second industrial objective of the project: To design sputtering targets with precisely controlled compositions, as required for academic research and for industrial production. A particular care will be given to the effect of the grain sizes and of the element dispersion in the targets, on the homogeneity and reproducibility of the resulting deposits.