HOROLOGICAL COMPONENT FORMED FROM AMAGNETIC BINARY CuNi ALLOY
A monolithic horological component comprising a binary amagnetic CuNi alloy, said component being obtained by a process comprising the production of a mold for said component by photolithography and a step for electrodeposition. The fabrication process for the monolithic horological component is selected from UV-LiGA type processes.
1 . A monolithic horological component comprising an amagnetic binary CuNi alloy, said component being obtained by a process comprising the production of a mold for said component by photolithography and a step of electrodeposition.
2 . The monolithic horological component according to claim 1 , wherein said component is a component of a movement of a timepiece.
3 . The monolithic horological component according to claim 1 , wherein said component is homogeneous and isotropic.
4 . The monolithic horological component according to claim 1 , constituted by a binary alloy Cu(x) Ni(100-x), in which 45<x<80, where x designates the atomic percentage of copper.
5 . The monolithic horological component according to claim 1 , comprising a binary alloy Cu(x) Ni(100-x), in which 55<x<75, where x designates the atomic percentage of copper.
6 . The monolithic horological component according to claim 1 , wherein said binary CuNi alloy is obtained from an electrodeposition bath solution comprising at least one Ni 2+ salt and one Cu 2+ salt, the Ni 2+ cations being in excess with respect to the Cu 2+ in a manner such that the reduction of Ni 2+ is controlled by kinetics, while the reduction of Cu 2+ is limited by mass transfer.
7 . The monolithic horological component according to claim 6 , wherein said electrodeposition bath solution comprises a Ni 2+ salt in a concentration of 0.1 M to 0.4 M, and a Cu 2+ salt in a concentration of 0.04 M to 0.1 M, said concentrations being adjusted in a manner such as to obtain a predetermined value for x.
8 . The monolithic horological component according to claim 6 , wherein said electrodeposition bath solution additionally comprises a chelating agent for Cu 2+ ions, in particular Na citrate, and in that a pH of the bath solution is adjusted to a value of 6.
9 . The monolithic horological component according to claim 6 , wherein said electrodeposition bath solution additionally comprises additives selected from wetting agents, brightening agents, levelling agents and stress-suppressing agents.
10 . The monolithic horological component according to claim 1 , obtained by a process selected from processes of a UV-LiGA type.
11 . The monolithic horological component according to claim 10 , wherein said process of the UV-LiGA type employs an Au/Cr/Si lithography substrate and a photoresistant SU-8 type resin, in that said substrate is exposed to an O 2 plasma before the electrodeposition step and in that said substrate acts as a cathode during the electrodeposition step.
12 . The monolithic horological component according to claim 11 , wherein the electrodeposition employs an anode comprising a noble metal, disposed parallel to and facing the cathode.
13 . The monolithic horological component according to claim 12 , wherein a temperature of the electrodeposition bath solution is kept constant during the electrodeposition, in particular adjusted to 40° C., and in that the bath solution is stirred during the electrodeposition.
14 . The monolithic horological component according to claim 10 , wherein the electrodeposition is carried out using a pulsed current, a duration of cathodic pulses being adjusted to between 5 ms and 2 s, the pulses being separated by pauses with zero current.
15 . The monolithic horological component according to claim 14 , wherein a current adjusted to a current density in the range −1 mA/cm 2 to −200 mA/cm 2 is applied during the cathodic pulses.
16 . The monolithic horological component according to claim 14 , wherein a current adjusted to a cathode potential, with respect to an Ag/AgCl electrode, in a range of −0.8V to −1.6 V is applied during the pulses.
17 . The monolithic horological component according to claim 14 , wherein the electrodeposition process is initiated by a nucleation pulse with a potential adjusted to between −0.8 V and −1.6 V, with respect to an Ag/AgCl electrode, or a current density adjusted to between −1 mA/cm 2 and −200 mA/cm 2 .
18 . The monolithic horological component according to claim 17 , wherein the nucleation pulse is carried out at −1 V, and with respect to an Ag/AgCl electrode, for 11 s.
19 . The monolithic horological component according to claim 17 , wherein the nucleation pulse is carried out in a galvanostatic mode with a current density which is half of that for the subsequent pulses.
20 . The monolithic horological component according to claim 1 , comprising a binary alloy Cu(x) Ni(100-x), in which x=55, where x designates the atomic percentage of copper.