Alloys at low nickel-release: Pd-Ni coatings on copper

Allergies created by metals in contact with the human body are becoming an increasingly important problem. Nickel is known to be an allergy-causing factor and Ni-containing alloys of coated items coming into direct and prolonged contact with the skin have to be tested to verify their Ni release before commerce. Samples coated with thin layers (0.3 mum and 0.04 mum and 0.04 mum Ar+ ion implanted [I.I.]) of a Pd-Ni alloy (90-10 wt%) were electrochemically tested in an alkaline (pH=12.4) solution. The coated samples were also tested in synthetic sweat solution, using the European EN 1811 test method. The electrochemical tests (potential vs. time, potentiodynamic test) and the synthetic sweat tests confirmed the good corrosion behavior of the very thin coatings. After the synthetic sweat test, it is possible to affirm that the Pd-Ni coatings are in accordance with the law proposed by the European Committee for Standardization (CEN) given that the nickel release was lower than 0.5 mug/cm(2)/week.