Final Report Summary - HYPONICK (Hypoallergenic nickel-free (imitation) jewellery by employing nano-structured galvanic coatings)
The HYPONICK project has obtained the support of the EC thanks to funding in its SME targeted scheme for Collective Research and Co-operative Research (CRAFT). The project started 1 September 2005 with a duration of 27 months. The main objective of the two-year CRAFT-project was to develop innovative nickel-free undercoats for hypoallergenic precious and semi-precious plated jewellery articles by electrodeposition of nanostructured coatings, thereby reducing the levels of exposure of (European) citizens to nickel towards zero. Although alternative undercoats exist, most of these are still on nickel basis (e.g. Pd-Ni) and these still give rise to allergic reactions on sensitive skin, despite the fact that these conform to European Union Directive 76/769/EEC- 12th Amendment (94/27/EC).
The main technical objective of the proposed research was to develop innovative completely nickel-free undercoats for hypoallergenic precious and semi-precious plated jewellery articles by electrodeposition of nanostructured coatings. These coatings can solve the issues that remain unsolved by present-day technology.
Targets were:
- 100 % complete absence of nickel and therefore fully hypoallergenic character;
- reduction of diffusion speed of Cu from the undercoat to the Au surface with > 90 % compared to conventional white bronze, thereby reducing gold surface tarnishing;
- increased durability of the gold plated article due to improved abrasion resistance and corrosion resistant properties. Target is improvement > factor two compared to conventional white bronze;
- reduced costs, 30 % for total coating stack.
First, materials and configuration requirements established on the basis of input of all participating SMEs. Base materials were defined and coating specifications were determined. Tests and standard for characterisation were selected and requirements concerning costs of the process were established.
Progress was made in development of nickel-, cyanide- and lead-free undercoats for jewellery applications. A nanocrystalline white bronze alloy bath (Cu-Sn-Zn) was studied based on boric acid / gluconate. Moreover, work was done to develop a bath based on methanesulphonic acid (MSA). Smooth films are obtained when high concentrations of specific non-ionic wetting agents are used. The targeted alloy composition of 60-70 % Cu, 30- 40 % Sn and 0-5 % Zn was achieved. Pulse reverse plating was investigated as an alternative to use of wetting agents to get rid of foaming effects. Further work was carried out on pulse reverse plating with Elsy's nickel-and lead free white bronze bath. A compositional change was clearly seen as function of plating frequency. Sample material was made and tested for performance. The results were characterised as very promising the by SMEs. After nine months in the project, all participants agreed to focus on nanocrystalline bath and pulse reverse plating.
Most, but not all objectives of the project were met. The process is entirely nickel free, and moreover free from cyanides and lead which are important assets and makes operation straightforward. The objectives with respect to the functional behaviour of the films deposited, both tarnishing and corrosion resistance were met. Aesthetically, both gloss and colour of the deposits are however not fully satisfactory for the high demands that are set in jewellery industry and need further optimisation. Pricewise, using nickel is still a better option. One of the main reasons for this is the relatively short life of the bath. Although much progress was made, the lifetime of the process bath is limited to several weeks due to oxidation of Sn(II). The bath is therefore best run under continuous load. Despite EU legislation the drive for industry to shift to nickel-free processing is unfortunately small.
The main technical objective of the proposed research was to develop innovative completely nickel-free undercoats for hypoallergenic precious and semi-precious plated jewellery articles by electrodeposition of nanostructured coatings. These coatings can solve the issues that remain unsolved by present-day technology.
Targets were:
- 100 % complete absence of nickel and therefore fully hypoallergenic character;
- reduction of diffusion speed of Cu from the undercoat to the Au surface with > 90 % compared to conventional white bronze, thereby reducing gold surface tarnishing;
- increased durability of the gold plated article due to improved abrasion resistance and corrosion resistant properties. Target is improvement > factor two compared to conventional white bronze;
- reduced costs, 30 % for total coating stack.
First, materials and configuration requirements established on the basis of input of all participating SMEs. Base materials were defined and coating specifications were determined. Tests and standard for characterisation were selected and requirements concerning costs of the process were established.
Progress was made in development of nickel-, cyanide- and lead-free undercoats for jewellery applications. A nanocrystalline white bronze alloy bath (Cu-Sn-Zn) was studied based on boric acid / gluconate. Moreover, work was done to develop a bath based on methanesulphonic acid (MSA). Smooth films are obtained when high concentrations of specific non-ionic wetting agents are used. The targeted alloy composition of 60-70 % Cu, 30- 40 % Sn and 0-5 % Zn was achieved. Pulse reverse plating was investigated as an alternative to use of wetting agents to get rid of foaming effects. Further work was carried out on pulse reverse plating with Elsy's nickel-and lead free white bronze bath. A compositional change was clearly seen as function of plating frequency. Sample material was made and tested for performance. The results were characterised as very promising the by SMEs. After nine months in the project, all participants agreed to focus on nanocrystalline bath and pulse reverse plating.
Most, but not all objectives of the project were met. The process is entirely nickel free, and moreover free from cyanides and lead which are important assets and makes operation straightforward. The objectives with respect to the functional behaviour of the films deposited, both tarnishing and corrosion resistance were met. Aesthetically, both gloss and colour of the deposits are however not fully satisfactory for the high demands that are set in jewellery industry and need further optimisation. Pricewise, using nickel is still a better option. One of the main reasons for this is the relatively short life of the bath. Although much progress was made, the lifetime of the process bath is limited to several weeks due to oxidation of Sn(II). The bath is therefore best run under continuous load. Despite EU legislation the drive for industry to shift to nickel-free processing is unfortunately small.
