Ignition device component produced by cold metal transfer process
The present invention relates to noble metal-containing components prepared by cold metal transfer (CMT) methods, along with methods of preparing such components by CMT. More especially, an advantageous method of preparing a platinum metal group metal or alloy containing ignition device component by CMT is provided.
1. A process for the production of an ignition device component by cold metal transfer comprising:
(i) providing a metal or alloy substrate and a metal or alloy feed wire, wherein the feed wire comprises a platinum group metal or platinum group metal containing alloy;
(ii) igniting an electric arc between the substrate and the feed wire;
(iii) decreasing the distance between a surface of the substrate and the feed wire until the feed wire contacts the substrate, thereby creating a short-circuit; and
(iv) increasing the distance between the substrate and the feed wire to break the short circuit and deposit metal or alloy from the feed wire onto the surface of the substrate to form a metal or alloy attachment on the surface of the substrate.
2. A process according to claim 1 , wherein the substrate comprises nickel or a nickel alloy, optionally comprising a copper core.
3. A process according to claim 2 , wherein the substrate comprises Inconel alloy.
4. A process according to claim 1 , comprising the production of a plurality of components using a cold metal transfer method, wherein a plurality of substrates is arranged in an array within a single cold metal transfer unit.
5. A process according to claim 4 , comprising performing steps (i) to (iv) for each substrate in the array simultaneously or sequentially.
6. A process according to claim 4 , wherein the spacing between central points on adjacent substrates is in the range 1 to 10 mm.
7. A process according to claim 1 , wherein the substrate is located within a recess or bore in a build plate of a cold metal transfer unit.
8. A process according to claim 7 , wherein the substrate is located within the recess such that the upper surface of the substrate is substantially level with the upper surface of the build plate, or protrudes above the upper surface of the build plate by a clearance of less than or equal to 5 mm.
9. A process according to claim 7 , wherein the substrate is held in position within the recess or bore.
10. A process according to claim 9 , wherein the substrate is held in position by means of abutment between a protrusion from the surface of the substrate and a protrusion from the inner surface of the bore.
11. A process according to claim 1 , wherein the step (i) of providing a metal or alloy substrate includes the following steps:
(ia) supplying an unsorted and disoriented plurality of substrates to a feeding machine;
(ib) orienting the substrates into a predetermined desired orientation using the feeding machine; and
(ic) transporting oriented substrates from an output line of the feeding machine into a predetermined desired position within a cold metal transfer unit.
12. A process according to claim 11 , wherein the substrates are transported using a handling robot, optionally wherein the handling robot transports a plurality of substrates at a time.
13. A process according to claim 1 , further comprising a step (v) selected from surface finishing and/or isostatic pressing of at least a part of the component.
14. A process according to claim 1 , which is a process for the production of a central or ground electrode of a spark plug.
15. A process according to claim 14 , which is a process for forming the tip of a central electrode of a spark plug on a substrate which represents the remainder of the central electrode.
16. An ignition device component obtained or obtainable by a process according to claim 1 .
17. An ignition device component according to claim 16 , which is an ignition device electrode.
18. A process for the production of a noble metal-containing component by cold metal transfer comprising:
(i) providing a metal or alloy substrate and a feed wire, wherein the feed wire comprises a noble metal or noble metal-containing alloy;
(ii) igniting an electric arc between the substrate and the feed wire;
(iii) decreasing the distance between a surface of the substrate and the feed wire until the feed wire contacts the substrate, thereby creating a short-circuit; and
(iv) increasing the distance between the substrate and the feed wire to break the short circuit and deposit metal or alloy from the feed wire onto the surface of the substrate to form a metal or alloy attachment on the surface of the substrate.
19. A process according to claim 18 , wherein the feed wire comprises a metal or alloy selected from the metals Ru, Rh, Pd, Ag, Os, Ir, Pt and Au, and alloys thereof.
20. A process according to claim 19 , which is a process for the production of a PGM-containing component, wherein the feed wire comprises a platinum group metal selected from Ru, Rh, Pd, Ir and Pt or an alloy thereof.