The Swatch Group Research and Development Ltd

Marion Gstalter

Christian Manasterski

A layer of lanthanum boride of stoichiometry LaBwhere x is between 9 and 12 is deposited on substrate, for example a stainless steel watch dial, and subsequently treated with a laser, such that the portion(s) of the layer treated with the laser change colour according to the laser power. This produces multicoloured surfaces having high resistance to corrosion and abrasion. The layer of LaBis deposited by PVD and by cathode sputtering, using a LaBtarget of purple-violet colour, such that the colour of the deposited layer differs from the colour of the target. The laser treatment at specific powers changes the stoichiometry of the layer in the treatment portions, such that the colour of these portions changes according to the stoichiometry obtained. At higher powers, the laser will remove the layer of LaB. Thus the colour of the treated portions is determined by the material of the substrate.

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Dombresson, Switzerland

Marion Gstalter