US3635805A - Working of metal bodies - Google Patents

Working of metal bodies Download PDF

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Publication number
US3635805A
US3635805A US751925A US3635805DA US3635805A US 3635805 A US3635805 A US 3635805A US 751925 A US751925 A US 751925A US 3635805D A US3635805D A US 3635805DA US 3635805 A US3635805 A US 3635805A
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US
United States
Prior art keywords
cathode
nitric acid
working
electrolyte
electrolytic
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 - Lifetime
Application number
US751925A
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English (en)
Inventor
Samuel Raviv
Elsa Rabinovitz
Shimon Malkiely
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.)
Israel Atomic Energy Commission
Original Assignee
Israel Atomic Energy Commission
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 IL2954768A external-priority patent/IL29547A/xx
Application filed by Israel Atomic Energy Commission filed Critical Israel Atomic Energy Commission
Application granted granted Critical
Publication of US3635805A publication Critical patent/US3635805A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23H—WORKING OF METAL BY THE ACTION OF A HIGH CONCENTRATION OF ELECTRIC CURRENT ON A WORKPIECE USING AN ELECTRODE WHICH TAKES THE PLACE OF A TOOL; SUCH WORKING COMBINED WITH OTHER FORMS OF WORKING OF METAL
    • B23H3/00—Electrochemical machining, i.e. removing metal by passing current between an electrode and a workpiece in the presence of an electrolyte
    • 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

Definitions

  • a process for the production of nitrous oxide comprising establishing an electrolytic circuit in which the elec' trolyte is nitric acid, one electrode is of an electronegative metal or metal alloy, which is not attacked at all or attacked only very slowly by nitric acid, and the other is of a conductive material inert to nitric acid under operational conditions, and flowing an electric current through this circuit under conditions which do not cause dissolution of the electronegative electrode. Under these conditions a nitrous oxide containing gas mixture evolves near the cathode and can be withdrawn therefrom.
  • the present invention consists in a method for working a metal or mineral body, comprising establishing an electrolytic circuit in which the electrolyte is nitric acid and the electrodes are inert to the electrolyte-under the operational conditions, provided that the cathode is of a different material than said body, introducing said body into the electrolyte in a proximity relationship with the cathode, flowing a unidirectional electric current through the circuit thereby to bring about local dis solution of the body, maintaining the proximityrelationship of the body with the cathode until the desired degree of local dissolution is achieved, and then withdrawing the body from the electrolyte.
  • the system may comprise two or more cathodes connected in parallel.
  • proximity relationship is used herein to describe the distance between the worked body and the cathode and is meant to imply either direct physical contact or a spaced relationship not exceeding 10 millimeters.
  • local dissolution implies dissolution within the zone, that is, in proximity relationship with a cathode.
  • the body is bored by placing one or more oblong cathodes each in proximity relationship to said body.
  • the diameter of an existing bore is widened by placing an oblong cathode so as to extend therethrough in axial direction and the electric current is made to flow until the bore is widened to the desired diameter.
  • a metal or mineral body is cut or engraved by bringing one or more cathodes into a proximity relationship with the body along a predetermined cutting line or lines.
  • a gradual movement of the body and each cathode towards each other as the operation proceeds may be necessary.
  • the electrodes used in carrying out the method according to the invention may be of any suitable material provided they are not chemically attacked by the nitric acid under the operating conditions.
  • the temperature of the nitric acid bath that is used in carrying out the method according to the invention and any temperature between the freezing and boiling points may be employed. Wherever possible it will be preferable to operate at room or only slightly elevated temperature.
  • the concentration of the nitric acid and/or the current intensity there are also no critical limitations for the concentration of the nitric acid and/or the current intensity. Both parameters have to be selected in accordance with the properties of the body to be worked, taking, however, into consideration that both the body and the electrodes must not be attacked chemically.
  • the method according to the invention differs basically from all hitherto known electrolytic processes.
  • the system comprises only a cathode, an anode and an electrolytic bath.
  • a body has to be worked in any way, electroplated, passivated or dissolved, e.g., in accordance with the above-mentioned Belgian Pat. No. 704.472, the body itself forms one of the electrodes, e.g., the cathode.
  • this electrode i.e., the body, changes in the course of the treatment.
  • anticathode In distinction therefrom, in the method according to the invention, three elements are present in the electrolytic bath, to wit, an anode, a cathode and the body that is being worked.
  • the body which is thus neither cathode nor anode, will for the reason of its proximity relationship with the cathode, be termed hereinafter as anticathode.”
  • anticathode In a system according to the invention only the anticathode changes in accordance with the treatment whereas cathodes and anodes remain substantially unaffected.
  • the treatment is completely topical and only a zone of the anticathode tat is in proximity relationship with the cathode is dissolved whereas the remaining part of the anticathode remains unaffected. It is due to this feature that a complete control of the process is possible and the anticathode may in accordance with the invention be shaped in any desired way.
  • the method according to the invention is based on local modifications of the electric surface properties of the anticathode, which modifications occur in the zone of close proximity to the cathode. As a consequence of these modifications a zone of the anticathode that is in proximity relationship with a cathode is depassivated to such an extent that it can be attacked chemically by nitric acid.
  • an electrolytic system in accordance with the invention comprises a vessel 1 holding a nitric acid bath 2.
  • a cathode 3 and an anode 4 Into vessel 1 dips a cathode 3 and an anode 4 and immersed in the bath and positioned in proximity relationship with the tip of cathode 3 is an anticathode 5 which is the body to be worked in accordance with the invention.
  • anode 4 is not electrically connected to the work body 5.
  • Cathode 3 is connected to the negative terminal and anode 4 to the positive terminal of a battery 6.
  • An ammeter A serves for measuring the current intensity and a voltmeter V for voltage determination.
  • the system further comprises switching means as well as voltage and current intensity controlling means which are all known per se and not illustrated in the wiring diagram.
  • anticathode 5 Where it is desired, for example, to bore a hole in anticathode 5 the DC is switched on and the anticathode 5 and cathode 3 are gradually moved towards each other as the boring proceeds. The operation continues as long as desired and is interrupted by switching off the current. The so-processed anticathode is then removed from the bath.
  • EXAMPLE 1 A cylindrical uranium rod of 35-millimeter diameter and 80-mm. long was cut across. For this purpose a platinum wire was wound around the circumferential line along which the cut was intended. The body was placed horizontally into a 1.5- liter bath of 4N HNO at 25 C. and the anode, equally a platinum wire, was so placed that its lower tip was 2 cms. above the uranium rodv An electric current of 12 volts and amperes was applied for 30 hours after which the rod was fully cut. During this operation the cathode, which formed a loop around the uranium rod, was permanently tensioned.
  • EXAMPLE 2 A uranium rod of the same dimension as that used in example l was bored across. To this end the loop-shaped cathode used in example 1 was replaced by a straight, pointed cathode whose lower tip was directed in direction of the intended bore. The bath was again 1.5 liter of 4N HNO solution, the voltage applied was from 10 to 12 volts, the current intensity from 5 to 8 amperes, and the temperature varied between and C. After 8.55 hours a diametrical bore was achieved whose inner diameter was 4 mm.
  • the same procedure was repeated for boring an axial bore into the rod (80 mm. length) and this was achieved after 26.30 hours.
  • the bore obtained in this way had an inner diameter of 2 mm.
  • EXAMPLE 6 A uranium rod measuring 35 mm. in diameter and 80 mm. in length was bored using an aluminum cathode and platinum anode, a 4N HNO solution, a current intensity of 4 amperes at a voltage of 10 volts. The operational temperature was 60 C. and after 6 hours a l2-mm. long bore was produced.
  • a method for working a metal body which is chemically inert to nitric acid comprising establishing an electrolytic circuit in which the electrolyte is nitric acid and the electrodes are inert to the electrolyte under the operating conditions provided that the cathode is of a different material than said body, introducing said body into the electrolyte in a proximity relationship with the cathode and not electrically connected to the anode, flowing a unidirectional electric current through the circuit thereby to bring about local dissolution of the body, maintaining the proximity relationship of the body with the cathode until the desired degree of local dissolution is achieved, and then withdrawing the body from the electrolyte.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Electrical Discharge Machining, Electrochemical Machining, And Combined Machining (AREA)
  • Electrolytic Production Of Metals (AREA)
US751925A 1968-02-29 1968-08-12 Working of metal bodies Expired - Lifetime US3635805A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
IL2798668 1968-02-29
IL2954768A IL29547A (en) 1968-02-29 1968-02-29 Working of metal bodies

Publications (1)

Publication Number Publication Date
US3635805A true US3635805A (en) 1972-01-18

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ID=26320431

Family Applications (1)

Application Number Title Priority Date Filing Date
US751925A Expired - Lifetime US3635805A (en) 1968-02-29 1968-08-12 Working of metal bodies

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US (1) US3635805A (US07709020-20100504-C00041.png)
BE (1) BE722485A (US07709020-20100504-C00041.png)
CH (1) CH508054A (US07709020-20100504-C00041.png)
DE (1) DE1790053A1 (US07709020-20100504-C00041.png)
FR (1) FR1586334A (US07709020-20100504-C00041.png)
GB (1) GB1234463A (US07709020-20100504-C00041.png)
NL (1) NL6815325A (US07709020-20100504-C00041.png)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5102520A (en) * 1990-10-31 1992-04-07 Behr Omri M Electrolytic etching process and apparatus

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5035780A (en) * 1988-03-25 1991-07-30 Agency Of Industrial Science And Technology Method of manufacturing a platinum tip

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2990282A (en) * 1958-10-29 1961-06-27 Warner C Wicke Method of etching and composition therefor
US3139394A (en) * 1962-06-20 1964-06-30 North American Aviation Inc Method and apparatus for electrochemical milling
US3485731A (en) * 1966-05-09 1969-12-23 Matsushita Electronics Corp Process for electrolytically etching indium arsenide

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2990282A (en) * 1958-10-29 1961-06-27 Warner C Wicke Method of etching and composition therefor
US3139394A (en) * 1962-06-20 1964-06-30 North American Aviation Inc Method and apparatus for electrochemical milling
US3485731A (en) * 1966-05-09 1969-12-23 Matsushita Electronics Corp Process for electrolytically etching indium arsenide

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5102520A (en) * 1990-10-31 1992-04-07 Behr Omri M Electrolytic etching process and apparatus

Also Published As

Publication number Publication date
DE1790053A1 (de) 1972-04-13
FR1586334A (US07709020-20100504-C00041.png) 1970-02-13
NL6815325A (US07709020-20100504-C00041.png) 1969-09-02
CH508054A (de) 1971-05-31
BE722485A (US07709020-20100504-C00041.png) 1969-04-01
GB1234463A (US07709020-20100504-C00041.png) 1971-06-03

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