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EP0046913B1 - Procédé pour le polissage chimique de pièces de niobium, en particulier d'une cavité résonnante - Google Patents

Procédé pour le polissage chimique de pièces de niobium, en particulier d'une cavité résonnante Download PDF

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Publication number
EP0046913B1
EP0046913B1 EP19810106339 EP81106339A EP0046913B1 EP 0046913 B1 EP0046913 B1 EP 0046913B1 EP 19810106339 EP19810106339 EP 19810106339 EP 81106339 A EP81106339 A EP 81106339A EP 0046913 B1 EP0046913 B1 EP 0046913B1
Authority
EP
European Patent Office
Prior art keywords
niobium
weight
acid mixture
polishing
volume
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP19810106339
Other languages
German (de)
English (en)
Other versions
EP0046913A1 (fr
Inventor
Yilmaz Dipl.-Phys. Uzel
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Siemens AG
Original Assignee
Siemens AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from DE19803032666 external-priority patent/DE3032666C2/de
Priority claimed from DE19803032679 external-priority patent/DE3032679C2/de
Application filed by Siemens AG filed Critical Siemens AG
Publication of EP0046913A1 publication Critical patent/EP0046913A1/fr
Application granted granted Critical
Publication of EP0046913B1 publication Critical patent/EP0046913B1/fr
Expired legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
    • C23F3/00—Brightening metals by chemical means
    • C23F3/04—Heavy metals
    • C23F3/06—Heavy metals with acidic solutions

Definitions

  • the invention relates to a process for the chemical polishing of niobium parts, in particular a cavity resonator, in an acid mixture containing HF, HN0 3 , H 2 S0 4 and H 2 0.
  • niobium is used as a material for superconducting cavity resonators.
  • Such cavity resonators can be provided in particular for particle accelerators.
  • high-frequency absorption takes place in the superconducting surface of these cavity resonators.
  • the surface layers should be composed as homogeneously as possible, as smoothly as possible and as free as possible from all kinds of disturbances.
  • a method for anodic polishing of the niobium parts of cavity resonators in which an electrolyte containing H Z S0 4 , HF and H 2 0 is used with a predetermined mixing ratio of these parts.
  • a temperature between 15 and 50 ° C is used and no constant voltage between 9 and 50 V is set such that damped current vibrations superimposed on the electrolyte current occur and at the latest after the current vibrations have completely subsided, the voltage is switched off until the during the Current vibrations built up oxide layer is resolved.
  • the measures according to the invention are based on the knowledge that an acid mixture containing HF, HN0 3 , H 2 S0 4 and H 2 0 can nevertheless be used to polish the niobium parts of a cavity resonator if very specific compositions of the mixture and certain process parameters be respected.
  • the reason why the known method does not lead to the desired polishing effect for superconducting niobium cavity resonators can be seen in the fact that the reaction is highly exothermic and depends in particular on the size of the niobium volume and the temperature.
  • a small niobium body such as a circular disk-shaped plate made of 0.5 mm thick niobium sheet with a diameter of 1 cm, does have a correspondingly low heat mass and therefore heats up somewhat after being introduced into the known acid mixture.
  • this temperature increase is generally not sufficient to achieve the polishing effect required for high-frequency applications.
  • a larger niobium body such as a resonator, because of its large thermal mass, even heat is extracted from the mixture surrounding it, so that there is an undesirable reduction in temperature on its surface.
  • the advantages achieved with the invention thus consist in the fact that with the specified mixing ratio, an increased temperature on the surfaces of the niobium parts is always guaranteed due to the predetermined volume ratio of acid to niobium material and the predetermined minimum temperature.
  • the grain boundaries are slightly etched, i.e. they become visible.
  • the grains with statistical orientations are not removed differently; i.e. it is advantageous not to observe any step formation at the grain boundaries. The grains therefore become extremely smooth if the niobium lattice is not severely disturbed by excessive cold forming.
  • the niobium parts should therefore be introduced into an acid mixture whose volume is at least 50 times the volume of the niobium material.
  • a particularly good polishing effect is achieved if the niobium parts are introduced into an acid mixture which contains about 6.5 to 8.5% by weight HF, 12.5 to 19.5% by weight HN0 3 , 46 to 62% by weight. % H 2 S0 4 and the remaining weight percent H 2 0 contains.
  • a sufficiently high temperature on the surfaces to be polished of the niobium parts introduced into the acid mixture is guaranteed in all cases if the acid mixture has a minimum temperature of 70 ° C.
  • the niobium parts to be polished were a cavity resonator of the TM 010 type, as is illustrated, for example, in the publication “Cryogenics”, January 1976, page 20, FIG. 6.
  • the resonator was composed of approximately 1 mm thick niobium sheet and had an axial extension of 50 mm.
  • the front, perforated disk-shaped, about 5 mm thick flange parts of the resonator with an outside diameter of 54 mm had a central opening of 12 mm diameter for axial coupling tubes.
  • the actual cylindrical resonator cavity with an inner diameter of 25 mm and an axial extension of 15 mm was arranged between the coupling tubes.
  • the resonator weight was about 195 g, so the volume was about 23 cm 3 .
  • the total surface area of the niobium parts of the resonator was approximately 175 cm2.
  • This resonator was polished in about 40 ml of an acid mixture according to the invention.
  • the acid mixture consisted of 25 volume percent 40% hydrofluoric acid, 25 volume percent 65% nitric acid and 50 volume percent 96% sulfuric acid. This corresponds to a composition of the acid mixture of about 7.3% by weight HF, 14.7% by weight HN0 3 , 56.9% by weight H 2 S0 4 and 21.1% by weight H 2 0.
  • This acid mixture of acids Commonly used concentrations were freshly prepared, sulfuric acid being added to the mixture of fluoric acid and nitric acid. An initial temperature of more than 75 ° C. was advantageous.
  • a further resonator of the same type with the same dimensions as in the previous example was polished in approximately 400 ml of an acid mixture according to the invention.
  • the acid mixture consisted of 80 ml of 40% hydrofluoric acid, 160 ml of 69% nitric acid and 160 ml of 98% sulfuric acid.
  • This acid mixture of acids of commonly used concentrations was freshly prepared, with the sulfuric acid being added to the mixture of fluoric acid and nitric acid.
  • An initial temperature of more than 75 ° C. was advantageous. Since the polishing process is very fast, 30 11 m were removed after only 30 seconds, and the inside of the resonator was shiny. While the inner surfaces of the resonator had an average roughness of about 2.5 ⁇ m before the polishing process, an average roughness of less than 0.3 ⁇ m was determined after polishing.
  • the method according to the invention is therefore particularly suitable for quick and easy polishing of the surfaces of cavity resonators made of niobium. Of course, it can also be used to polish any other niobium parts.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Grinding And Polishing Of Tertiary Curved Surfaces And Surfaces With Complex Shapes (AREA)
  • ing And Chemical Polishing (AREA)

Claims (6)

1. Procédé de polissage chimique de pièces en niobium, dans un mélange acide contenant HF, HN03, H2SO4 et H20, caractérisé en ce qu'il consiste à mettre les pièces en niobium dans un mélange acide qui a une température minimale de 40°C, dont le volume représente au moins 15 fois le volume du matériau en niobium et qui contient environ a % en poids de HF, environ β % en poids de HN03, environ y % en poids de H2S04 et H20 pour les pourcentages en poids restants, a étant compris entre 5 et 10, étant compris entre 11 et 26 et y entre 36 et 66.
2. Procédé de polissage suivant la revendication 1, caractérisé en ce qu'il consiste à mettre les pièces en niobium dans un mélange acide, dont le volume représente au moins 50 fois le volume du matériau en niobium.
3. Procédé de polissage suivant la revendication 1 ou 2, caractérisé en ce qu'il consiste à mettre les pièces en niobium dans un mélange acide qui contient environ de 6,5 à 8,5% en poids de HF, de 12,5 à 19,5% en poids de HN03, de 46 à 62% en poids de H2SO4 et H20 pour les pourcentages en poids restants.
4. Procédé de polissage suivant l'une des revendications 1 à 3, caractérisé en ce qu'il consiste à utiliser un mélange acide qui contient environ 7,3% en poids de HF, 14,7% en poids de HN03, 56,9% en poids de H2SO4 et 21,1% en poids de H2O.
5. Procédé de polissage suivant l'une des revendications 1 à 4, caractérisé en ce qu'il consiste à mettre les pièces de niobium dans un mélange acide qui a une température minimale de 70°C.
6. Procédé de polissage suivant l'une des revendications 1 à 5, caractérisé en ce qu'il consiste à mettre les pièces en niobium dans un mélange acide fraîchement préparé auquel est ajoutée, à titre de dernier acide, la proportion prescrite de H2SO4.
EP19810106339 1980-08-29 1981-08-14 Procédé pour le polissage chimique de pièces de niobium, en particulier d'une cavité résonnante Expired EP0046913B1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
DE3032679 1980-08-29
DE3032666 1980-08-29
DE19803032666 DE3032666C2 (de) 1980-08-29 1980-08-29 Verfahren zum chemischen Polieren von Niob-Teilen, insbesondere eines Hohlraumresonators
DE19803032679 DE3032679C2 (de) 1980-08-29 1980-08-29 Chemisches Polierverfahren für Niob-Teile, insbesondere von Hohlraumresonatoren

Publications (2)

Publication Number Publication Date
EP0046913A1 EP0046913A1 (fr) 1982-03-10
EP0046913B1 true EP0046913B1 (fr) 1984-12-05

Family

ID=25787502

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19810106339 Expired EP0046913B1 (fr) 1980-08-29 1981-08-14 Procédé pour le polissage chimique de pièces de niobium, en particulier d'une cavité résonnante

Country Status (1)

Country Link
EP (1) EP0046913B1 (fr)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP5807938B2 (ja) 2012-07-11 2015-11-10 マルイ鍍金工業株式会社 空洞管の研磨用電極とそれを用いた電解研磨方法

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
IL33668A0 (en) * 1970-01-06 1970-03-22 Raviv S Polishing of metals
DE2409180C3 (de) * 1974-02-26 1981-06-19 Siemens AG, 1000 Berlin und 8000 München Verfahren zum anodischen Polieren von Niobteilen

Also Published As

Publication number Publication date
EP0046913A1 (fr) 1982-03-10

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