Plasma torch electrode materials and related systems and methods

Patent metadata

Field	Value
Publication number	US-9516738-B2
Application number	US-201414500270-A
Country	US
Kind code	B2
Filing date	Sep 29, 2014
Priority date	Sep 30, 2013
Publication date	Dec 6, 2016
Grant date	Dec 6, 2016

Abstract

In some aspects, multi-metallic emissive inserts shaped to be disposed within an electrode for a plasma arc torch electrode can include an exposed emitter surface at a distal end of the emissive insert to emit a plasma arc from the electrode, wherein the emissive insert comprises a first emissive material and about 8 weight percent to about 50 weight percent yttrium.

First claim

What is claimed:

1. An electrode for a plasma arc torch, the electrode comprising:
a body formed of an electrically conductive material, the body having a first end and a second end; and
an emissive portion comprising a multi-metallic insert disposed within the first end, the multi-metallic insert including at least two non-oxidized metallic materials combined into a two-phase alloy, one of the non-oxidized metallic materials being about 5 weight percent to about 50 weight percent of metallic yttrium.

2. The electrode of claim 1 wherein the multi-metallic insert comprises at least one of hafnium or zirconium.

3. The electrode of claim 1 wherein the multi-metallic insert is substantially free of oxygen.

4. The electrode of claim 1 wherein, after an operational usage of the electrode, a thermionic emitter surface layer is formed along an exposed surface of the multi-metallic insert, the thermionic emitter surface layer having a composition different than a composition of a non-exposed portion of the multi-metallic insert.

5. The electrode of claim 1 wherein a portion of the multi-metallic insert comprises discrete regions of yttrium.

6. The electrode of claim 1 wherein the multi-metallic insert includes about 12 weight percent to about 25 weight percent yttrium.

7. The electrode of claim 1 wherein the multi-metallic insert includes an emissive surface with a surface area exposed to plasma gas, the emissive surface area having a size that is selected in coordination with an operating current carried by the electrode so that a current density during cutting is between about 35,000 amperes/inch to about 37,000 amperes/inch 2 .

8. The electrode of claim 1 wherein the multi-metallic insert further comprises at least one of calcium or magnesium.

9. The electrode of claim 1 wherein the two non-oxidized metallic materials are alloyed together.

10. The electrode of claim 1 wherein the multi-metallic insert is in contact with the body.

11. The electrode of claim 1 wherein the multi-metallic insert has an oxygen-rich environment material loss rate of about 5 nanograms per coulomb.

12. The electrode of claim 1 wherein the multi-metallic insert comprises an inner first portion and an outer second portion, the second portion formed of an emitter alloy with a liquid phase change temperature of greater than about 2800 degrees Celsius.

13. A plasma arc torch for a plasma cutting system, the plasma arc torch comprising:
a torch body;
a nozzle disposed within the torch body; and
an electrode mounted relative to the nozzle in the torch body to define a plasma chamber, the electrode including:
an electrode body formed of a thermal conductivity material, the electrode body having a first end and a second end defining a longitudinal axis; and
an emissive portion comprising a multi-metallic insert disposed within the first end, the multi-metallic insert including at least two non-oxidized metallic materials combined into a two-phase alloy, one of the non-oxidized metallic materials being about 5 weight percent to about 50 weight percent of metallic yttrium.

14. The plasma arc torch of claim 13 wherein the multi-metallic insert includes about 12 weight percent to about 25 weight percent yttrium.

15. A multi-metallic emissive insert shaped to be disposed within a plasma arc torch electrode, the emissive insert comprising:
an exposed emitter surface at a distal end of the emissive insert to emit a plasma arc from the electrode,
wherein the emissive insert comprises a first emissive material and about 5 weight percent yttrium to about 50 weight percent yttrium combined into a two-phase alloy.

16. The plasma arc torch of claim 15 wherein the multi-metallic insert includes an emissive surface with a surface area exposed to plasma gas, the emissive surface area having a size that is selected in coordination with an operating current carried by the electrode so that a current density during cutting is between about 35,000 amperes/inch to about 37,000 amperes/inch 2 .

17. The emissive insert of claim 15 wherein the yttrium and the first emissive material are alloyed in at least one region along the emitter surface after a use of the emitter.

18. The emissive insert of claim 15 wherein the multi-metallic insert includes about 12 weight percent yttrium to about 30 weight percent yttrium.

19. The emissive insert of claim 15 wherein the emitter surface defines a surface area configured to be exposed to plasma gas, the emitter surface area having a size that is selected in coordination with an operating current carried by the electrode so that a current density during cutting is between about 35,000 amperes/inch 2 to about 37,000 amperes/inch 2 .

20. The emissive insert of claim 15 further comprising a thermionic emitter surface layer formed along the emitter surface after at least one usage, the thermionic emitter surface layer comprising a different material composition than a remaining portion of the multi-metallic insert.

21. The emissive insert of claim 15 , wherein the emissive insert includes discrete regions of yttrium and hafnium.

22. The emissive insert of claim 15 wherein the elongated emissive insert has a generally cylindrical shape.

23. The emissive insert of claim 15 wherein the first emissive material comprises hafnium or zirconium.

24. The emissive insert of claim 15 wherein the emissive insert is disposed within a plasma arc torch electrode.

25. A method comprising:
forming a multi-metallic region of an emitter insert for a plasma arc torch electrode, the multi-metallic region comprising a first emissive material and about 5 weight percent to about 50 weight percent yttrium metal combined into a two-phase alloy; and
disposing the emitter insert in a recess formed at an end of the plasma arc torch electrode.

26. The method of claim 25 wherein the forming the multi-metallic region includes forming discrete regions of the yttrium metal.

27. The method of claim 25 further comprising treating at least a portion of the multi-metallic region, thereby forming an emitter layer comprising a combined region of the base material and the yttrium metal.

28. The method of claim 27 wherein the treating including supplying a current to heat.

29. The method of claim 25 further comprising forming a layer of an alloy of the yttrium metal and the first emissive material.

30. The method of claim 25 further comprising forming an exposed layer comprising yttrium and oxygen.

31. The method of claim 25 wherein the emitter layer has a thickness that is less than about 0.030 inches.

32. The method of claim 25 wherein the multi-metallic region includes about 12 weight percent to about 30 weight percent yttrium.

33. An electrode for a plasma arc torch, the electrode comprising:
an electrically conductive material body having a first end and a second end; and
an emissive multi-metallic insert disposed within the first end of the body, the multi-metallic insert formed of at least two non-oxidized metallic materials combined into a two-phase alloy, one of the non-oxidized metallic materials being about 5 weight percent to about 50 weight percent of metallic yttrium.

Assignees

• Hypertherm Inc

Inventors

• Wittmann Markus
• Peters John
• Shipulski E Michael

Classifications

• H05H1/34 Primary

  Details, e.g. electrodes, nozzles · CPC title

• H05H2001/3442

  Electricity · mapped topic

• Y10T29/49208

  by assembling plural parts · CPC title

• H05H1/3442

  Cathodes with inserted tip · CPC title