WO2022240729A1 - Chemical soak to remove furnace contamination without disrupting surface oxide or removing bulk materials - Google Patents
Chemical soak to remove furnace contamination without disrupting surface oxide or removing bulk materials Download PDFInfo
- Publication number
- WO2022240729A1 WO2022240729A1 PCT/US2022/028290 US2022028290W WO2022240729A1 WO 2022240729 A1 WO2022240729 A1 WO 2022240729A1 US 2022028290 W US2022028290 W US 2022028290W WO 2022240729 A1 WO2022240729 A1 WO 2022240729A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- niobium
- soak
- article
- contamination
- nitrogen
- Prior art date
Links
- 238000011109 contamination Methods 0.000 title claims abstract description 28
- 239000000126 substance Substances 0.000 title abstract description 15
- 239000000463 material Substances 0.000 title description 6
- 238000000034 method Methods 0.000 claims abstract description 43
- 239000010955 niobium Substances 0.000 claims abstract description 41
- 229910052758 niobium Inorganic materials 0.000 claims abstract description 32
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 claims abstract description 32
- 238000002791 soaking Methods 0.000 claims abstract description 4
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 48
- 229910052757 nitrogen Inorganic materials 0.000 claims description 24
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 7
- 229910017604 nitric acid Inorganic materials 0.000 claims description 7
- 238000001802 infusion Methods 0.000 abstract description 6
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 8
- 238000010438 heat treatment Methods 0.000 description 7
- QPJSUIGXIBEQAC-UHFFFAOYSA-N n-(2,4-dichloro-5-propan-2-yloxyphenyl)acetamide Chemical compound CC(C)OC1=CC(NC(C)=O)=C(Cl)C=C1Cl QPJSUIGXIBEQAC-UHFFFAOYSA-N 0.000 description 6
- 238000011282 treatment Methods 0.000 description 6
- 238000005275 alloying Methods 0.000 description 4
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 4
- 239000001301 oxygen Substances 0.000 description 4
- 229910052760 oxygen Inorganic materials 0.000 description 4
- 238000004090 dissolution Methods 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 238000005498 polishing Methods 0.000 description 3
- 239000003870 refractory metal Substances 0.000 description 3
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- 239000013590 bulk material Substances 0.000 description 2
- 230000008021 deposition Effects 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 239000001257 hydrogen Substances 0.000 description 2
- 229910052739 hydrogen Inorganic materials 0.000 description 2
- 238000002347 injection Methods 0.000 description 2
- 239000007924 injection Substances 0.000 description 2
- 238000007669 thermal treatment Methods 0.000 description 2
- 239000010409 thin film Substances 0.000 description 2
- 239000002253 acid Substances 0.000 description 1
- CFJRGWXELQQLSA-UHFFFAOYSA-N azanylidyneniobium Chemical compound [Nb]#N CFJRGWXELQQLSA-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000001311 chemical methods and process Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 150000004767 nitrides Chemical class 0.000 description 1
- 238000007788 roughening Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25F—PROCESSES FOR THE ELECTROLYTIC REMOVAL OF MATERIALS FROM OBJECTS; APPARATUS THEREFOR
- C25F3/00—Electrolytic etching or polishing
- C25F3/16—Polishing
- C25F3/22—Polishing of heavy metals
- C25F3/26—Polishing of heavy metals of refractory metals
Definitions
- the invention relates to SRF (superconducting radio frequency) technology, and more particularly to a novel method for removing furnace contamination without disrupting surface oxide or removing bulk materials.
- the current invention provides a method of removing furnace contamination on niobium cavities to increase the quality factor (Qo) and the accelerating gradient (Eacc) of SRF accelerator cavities.
- Performing a nitric soak, with nitric acid (HN03) at or below 70% concentration can remove contamination which can't be removed by conventional sulfuric/HF EP, HF soaking, which in turn can improve both Qo and RF accelerating gradients in niobium.
- the chemical soak can also remove contamination from a niobium surface without removing the native oxide or bulk niobium removals, - such as after infusion or mid-T baking.
- a first object of the invention is to provide an improved method of removing furnace contamination on niobium cavities to increase the quality factor (Qo) and the
- a second object of the invention is to provide an improved method of removing furnace contamination without disrupting surface oxide or removing bulk materials.
- a further object of the invention is to provide an improved method of removing furnace contamination without roughening the niobium surface like conventional BCP does.
- Another object of the invention is to provide a chemical process that may be used after infusion, mid-T bake, and thermal diffusion of native oxide but which does not remove the oxide.
- Another object of the invention is to provide a chemical soak that uses a chemical which is readily available and is compatible with almost everyone’ s chemical systems.
- Fig. 1 is a plot of the quality factor (Qo) of the cavity alone as a function of the accelerating gradient (Eacc), in MV/m, for a conventional (EP) process versus a nitrogen- doped cavity with furnace contamination and the subsequent contamination removal by a nitric-soak embodiment according to the invention.
- Fig. 2 is a plot of the quality factor (Qo) of the cavity alone as a function of the accelerating gradient (Eacc) for a conventional EP process versus a nitrogen-doped cavity with furnace contamination and the subsequent contamination removal by a nitric-soak percentage embodiment according to the invention.
- Fig. 3 is a plot of the quality factor (Qo) of the cavity alone as a function of the accelerating gradient (Eacc), in MV/m, for a conventional high gradient nitrogen doped cavity process versus a nitrogen-doped cavity with furnace contamination and the subsequent contamination removal by a nitric-soak embodiment according to the invention.
- Fig. 4 is a conceptual drawing depicting a nitrogen doping method after heat treatment.
- FIG. 5 is a conceptual drawing depicting a nitrogen doping method after electropolishing.
- Fig. 6 is a conceptual drawing depicting a nitrogen doping method after a chemical soak.
- Fig. 7 is a conceptual drawing depicting a mid-T bake/oxygen alloying method according to the invention after heat treatment.
- Fig. 8 is a conceptual drawing depicting the mid-T bake/oxygen alloying method according to the invention after chemical soak.
- the current invention is a chemical removal step removal method for niobium (Nb) that does not remove the surface oxide or remove any bulk material while advantageously removing furnace contamination ⁇
- the method can be used on niobium (Nb) cavities to increase the gradient and quality factor (Qo) of SRF cavities when the niobium metal is heat-treated in the non-reducing environment (vacuum). This method will likely be highly advantageous in the future, where infusion (nanometer nitrogen) and mid-T bake cavity (nanometer oxide) production is opening new avenues for cavity processing.
- mid-T bake refers to a bake at 160°C to 450°C, or essentially raising the oven temperature to 160°C and higher, but stopping before oxide (Nb05) dissolution occurs.
- Conventional niobium cavity bakes which are typically at a range of 100°C to 160°C, are referred to as “standard bakes” or “magic bakes”.
- Another conventional bake is at a range of 75°C to 120°C.
- the meaning of the term “bake(s)” as used herein refers to a thermal treatment under vacuum (traditionally at a pressure less than ⁇ 5- 6mbar), and usually inside a vacuum oven, or at lower temperatures using the cavity itself as the vacuum vessel while externally heating the cavity.
- Figs. 1 through 3 present the plotted results of each test condition, with the resultant Q° plotted as a function of Eacc(MV/m).
- the current invention is a chemical removal step that does not remove the oxide or remove any bulk material while still removing furnace contamination ⁇ This has never been shown to produce any positive result until now.
- This technique may be highly advantageous in the future, where infusion (nanometer nitrogen) and mid-T bake cavity (nanometer oxide) production is opening new avenues for cavity processing.
- mid-T bake refers to a bake at 160°C to 450°C or essentially raising the bake temperature to 160°C and higher but stopping before oxide dissolution occurs.
- Conventional niobium cavity bakes which are typically at a range of 100°C to 160°C, are referred to as “standard bakes” or “magic bakes”.
- Another conventional bake is at a range of 75°C to 120°C.
- Fig. 1 there is shown a plot of the quality factor (Qo) of a single-cell cavity as a function of the accelerating gradient (Eacc) in MV/m for a conventional EP process versus before and after a nitric soak embodiment according to the invention.
- the conventional EP process (baseline - o) included electropolishing at 15° C plus a 24 hour bake at 110°C.
- a nitrogen doping baseline ( ⁇ ) included 3 minutes of nitrogen treatment, followed by 60 minutes of vacuum, followed by electropolishing (EP) removal at 13° C to remove 67 kilocoulombs ( ⁇ 5-7 microns) from the surface of the niobium cavity.
- a nitric soak ( ⁇ ) post the doping baseline consisted of a nitric soak (nitric acid (HN03) at 70% concentration) for 1 hour, followed by 5 rinses of HF. After the nitric soak and lOx HF rinse to refresh the oxide, the cavity performed as expected.
- Fig. 2 there is shown a plot of the quality factor (Qo) of the cavity as a function of the accelerating gradient (Eacc) in MV/m for a conventional EP process versus vs baseline nitrogen doping and two nitric soak embodiments according to the invention.
- the conventional EP process baseline - 0
- the nitrogen doping baseline (3N120 - o) included 3 minutes of nitrogen treatment followed by 120 minutes of vacuum at 800°C with a pre-anneal at 925°C in the same run. Post doping the cavity received a conventional 8-mciron EP done at 13°C .
- a first nitric soak embodiment (D) included a nitric soak (30% concentration) for 1 hour.
- a second nitric soak embodiment ( ⁇ ) included a nitric soak (50% concentration) for 1 hour.
- the 30% nitric soak at 1 hour improved the Qo, although not as much as expected and the gradient did not improve.
- the 50% nitric soak improved the Qo further to the expected level for 3N120 doping although the gradient did not improve.
- Fig. 3 there is shown a plot of the quality factor (Qo) of the cavity as a function of the accelerating gradient (Eacc) in MV/m for a conventional high gradient doped cavity vs a reset and redoping in a contaminated furnace followed by a nitric soak
- a nitrogen doping baseline ( ⁇ ) included 3 minutes of nitrogen treatment, followed by 60 minutes of vacuum, followed by EP of 5 microns.
- the cavity received a 50 micron reset and a redoping ( ⁇ ) identical to the baseline doping ran with a change to the EP of 8 microns.
- a nitric soak ( ⁇ ) post the doping reset consisted of a nitric soak (70% concentration) for 1 hour, followed by 5 rinses of HF. The nitric acid returned the high field results up to 32 MV/m.
- the chemical removal method of the present invention would be beneficial in the manufacture of SRF cavities or in processing of surface-sensitive refractory metals that requires heat treatment.
- nitrogen doped refers to a vacuum furnace treatment above the native oxide dissolution temperature of approximately 450°C, followed by a gas injection of nitrogen (typically at about 30mbar) at a higher temperature (traditionally 800-1000°C) for a short time (20 minutes) and later
- FIG. 4 With reference to Figs. 4-6, there is shown a representation of the various steps for removing furnace contamination from a nitrogen doped surface after heat treatment and electro polishing .
- a furnace contaminate is deposited in or on the nitrogen doped surface while at high temperature during the nitrogen doping treatment (Fig. 4).
- Post doping there is an EP step (Fig. 5)which removes the nitrides from the surface to reveal the enhanced nitrogen doped niobium surface.
- the eletro-polishing does not remove the furnace contamination.
- Only by performing a post EP chemical soak embodiment (Fig. 6) according to the invention is the furnace contamination successfully removed.
- FIGs. 7-8 there is shown the sequence of steps in a mid-T bake/oxygen alloying method according another embodiment of the invention.
- a furnace contaminate is deposited on the niobium during the mid-T bake thermal treatment (Fig. 7).
- a chemical soak embodiment (Fig. 8) according to the invention is used to remove the contaminate without disturbing the surface oxide.
- Future applications of the technology could be in superconducting niobium accelerators (IFC and EIC) as well as contemporary SRF accelerators, in thin films refractory deposition where bulk or oxide removal is not desirable and which also requires heat treatments, or in furnace-annealed refractory metals that are surface sensitive.
Abstract
Description
Claims
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP22808113.9A EP4337412A1 (en) | 2021-05-12 | 2022-05-09 | Chemical soak to remove furnace contamination without disrupting surface oxide or removing bulk materials |
AU2022272616A AU2022272616A1 (en) | 2021-05-12 | 2022-05-09 | Chemical soak to remove furnace contamination without disrupting surface oxide or removing bulk materials |
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US202163187457P | 2021-05-12 | 2021-05-12 | |
US63/187,457 | 2021-05-12 | ||
US17/739,097 US20220364257A1 (en) | 2021-05-12 | 2022-05-07 | Chemical soak to remove furnace contamination without disrupting surface oxide or removing bulk materials |
US17/739,097 | 2022-05-07 |
Publications (1)
Publication Number | Publication Date |
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WO2022240729A1 true WO2022240729A1 (en) | 2022-11-17 |
Family
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Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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PCT/US2022/028290 WO2022240729A1 (en) | 2021-05-12 | 2022-05-09 | Chemical soak to remove furnace contamination without disrupting surface oxide or removing bulk materials |
Country Status (4)
Country | Link |
---|---|
US (1) | US20220364257A1 (en) |
EP (1) | EP4337412A1 (en) |
AU (1) | AU2022272616A1 (en) |
WO (1) | WO2022240729A1 (en) |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3453378A (en) * | 1967-01-19 | 1969-07-01 | North American Rockwell | Superconductive joint |
US3687823A (en) * | 1969-05-31 | 1972-08-29 | Siemens Ag | Method of producing superconductive cavity resonators,particularly for particle separators |
US3784452A (en) * | 1971-02-12 | 1974-01-08 | Siemens Ag | Method of treating the surface of superconducting niobium cavity resonators |
US4487637A (en) * | 1983-10-14 | 1984-12-11 | Cornell Research Foundation, Inc. | Purification of niobium |
US20200260566A1 (en) * | 2019-02-07 | 2020-08-13 | Fermi Research Alliance, Llc | Methods and systems for treating superconducting cavities |
-
2022
- 2022-05-07 US US17/739,097 patent/US20220364257A1/en active Pending
- 2022-05-09 AU AU2022272616A patent/AU2022272616A1/en active Pending
- 2022-05-09 WO PCT/US2022/028290 patent/WO2022240729A1/en active Application Filing
- 2022-05-09 EP EP22808113.9A patent/EP4337412A1/en active Pending
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3453378A (en) * | 1967-01-19 | 1969-07-01 | North American Rockwell | Superconductive joint |
US3687823A (en) * | 1969-05-31 | 1972-08-29 | Siemens Ag | Method of producing superconductive cavity resonators,particularly for particle separators |
US3784452A (en) * | 1971-02-12 | 1974-01-08 | Siemens Ag | Method of treating the surface of superconducting niobium cavity resonators |
US4487637A (en) * | 1983-10-14 | 1984-12-11 | Cornell Research Foundation, Inc. | Purification of niobium |
US20200260566A1 (en) * | 2019-02-07 | 2020-08-13 | Fermi Research Alliance, Llc | Methods and systems for treating superconducting cavities |
Also Published As
Publication number | Publication date |
---|---|
EP4337412A1 (en) | 2024-03-20 |
US20220364257A1 (en) | 2022-11-17 |
AU2022272616A1 (en) | 2023-12-21 |
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