Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
  • C22B4/00—Electrothermal treatment of ores or metallurgical products for obtaining metals or alloys
• • 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
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
  • C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases
  • C23C8/36—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases using ionised gases, e.g. ionitriding
• • 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
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
  • C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases
  • C23C8/36—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases using ionised gases, e.g. ionitriding
  • C23C8/38—Treatment of ferrous surfaces
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F41—WEAPONS
  • F41A—FUNCTIONAL FEATURES OR DETAILS COMMON TO BOTH SMALLARMS AND ORDNANCE, e.g. CANNONS; MOUNTINGS FOR SMALLARMS OR ORDNANCE
  • F41A21/00—Barrels; Gun tubes; Muzzle attachments; Barrel mounting means
  • F41A21/22—Barrels which have undergone surface treatment, e.g. phosphating
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
  • H01J37/32—Gas-filled discharge tubes
  • H01J37/32009—Arrangements for generation of plasma specially adapted for examination or treatment of objects, e.g. plasma sources
  • H01J37/32018—Glow discharge
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S148/00—Metal treatment
  • Y10S148/902—Metal treatment having portions of differing metallurgical properties or characteristics
  • Y10S148/903—Directly treated with high energy electromagnetic waves or particles, e.g. laser, electron beam
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S422/00—Chemical apparatus and process disinfecting, deodorizing, preserving, or sterilizing
  • Y10S422/906—Plasma or ion generation means

Definitions

• This invention relates to the production of improved surface layers on tubes of iron, steel or iron alloys, more particularly gun tubes. Owing to the great stresses-to which such tubes are exposed by corrosion, erosion, firing, etc., their surface is quickly attacked and destroyed. More particularly gun tubes, owing to rapid repeated firing, are subject to considerable wear, so that they become useless after a short time and have to be replaced.
• the invention it is possible, according to the invention, to increase the resistance of the tubes substantially, by improving them through ion bombardment in a glow discharge; It is possible to use ions of nitrogen, carbon, silicon, boron, metal, hydrogen and others, alone or in admixture with'one another.
• This treatment is characterised by the feature that use is made as a means for heating up to the required reaction temperature, of a glow discharge at any desired gas pressure.
• the electric glow discharge is preferably effected by periodic supply of energy of short duration, whereby the energy pulses of short duration are at least 10% higher than the permanent voltage.
• the intervals of rest are thereby equal to, or greater than, the periods of time of the increased energy supply.
• the glow discharge is thereby operated with about 0.2-5 Watts per cm?v of the surface of the ,object to be treated.
• gases may be admixed to the gas'used for the treatment.
• the latter is nitrogen, it is especially advantageous to add to it hyrogen in the ratio of 1:10 up to 1:25.
• the treating gases are purified, in order to remove also small amounts of foreign gases, e.g. oxygen, or when working with nitrogen for instance, also small amounts of hydrocarbons.
• This purification of the treating gases may advantageously be effected by means of ferrosilicon, ferroaluminium or other absorbent at higher temperatures of about 600-1000" C.
• the treatment is preferably effected with flowing gases, whereby the effective amount of gas should be equal to, or greater than, the consumption in reaction gas. It is an'advantage to carry out the treatment until the improving layer has reached a thickness of about ,4 mm. or more.
• the tubes are connected as a cathode of the glow discharge.
• the leads to the electrodes are insulated and screened with respect to the gas discharge by means of a gap.
• a wire may be disposed in the axis of the tube, to which a voltage is also applied.
• the total electric power that is applied should be at least, 3 or 5 or 10 kw.
• the articles to be improved are subjected, prior to the actual treatment, to an ion bombardment of reducing gases, such as hydrogen or the like. Thereby, it is an advantage to maintain the articles at a high temperature by means of a glow current.
• This preliminary treatment improves the technical properties of the material for instance, by the removal of small amounts of sulphur or phosphorus, e.g. with respect to the impact resistance proving elements.
• a gun tube is verticallysuspended in a etc., and prepares the surface of the articles to be treated in a substantial way for the reception of the actual imgas discharge chamber and connected to the negative pole of a source of DC voltage, e.g. a rectifier, capable of supplying a current of a few amps. in 'a glow discharge at a voltage of a few hundred volts, which glow discharge takes place in a gaseous atmosphere at a pressure of, for instance, a few mm. Hg.
• the positive pole of the source of voltage is connected to an anode introduced in a gas discharge chamber or to the metal wall of the gas discharge chamber.
• the gas discharge takes place between the gun tube acting as a cathode and the part of the anode connected to the positive pole of the source of voltage.
• Use is made of a gas containing nitrogen which has been purified by means of ferrosilicon at high temperature before introduction into the discharge chamber, for instance a mixtureof nitrogen and hydrogen or ammonia gas, 'or ammonia enriched with nitrogen, or diluted with hydrogen or another suitable gas, for instance a rear gas. 7
• an ammonia gas is produced with a pressure of 0.6 mm. Hg in an evacuated metal vessel in which the gun tube is suspended, the positive pole of a' DC.
• This screening is advantageously effected by' the provision of a narrow gap between the conductors of different potential in such a way that the gap, seen from the interior of the vessel, is in front of the insulation, so that the glow cannot reach the insulating material.
• the tube After treatment of about 24 hours, the tube has a very hard surface layer, which is not brittle and,therefore, does not tend to splinter oif, and is thus characterized by a high degree of ductility despite its increased hard ness.
• a further advantage lies therein that the glow discharge acts with suflicient intensity also on the parts of the tu e which are most removed from the ends of the tube, whereby a more uniformly nitrided surface is obtained.
• the uniform treatment may be assisted by the provision of a wire in the the axis of the tube, to which the elec tric voltage is also applied.
• the wire may .beconnected to the positive or negative pole of the voltage. If such a wire is connected to the negative pole the wire is disintegrated and the material that is disintegrated may be deposited on the interior of the tube or with a longer period of time be diffused therein.
• the high temperature thereby required on the inner surface of the tube may be obtained by supplying the energy periodically for sufficiently short periods of time, as above described.
• a suitable gas pressure with respect to the distance of the central wire from the inner surface of the tube a discharge is obtained in which very high energies are released.
• the glow discharge chambers that mainly come into question are metal chambers which are sufiiciently long to accommodate a tube and have a sufificiently large diameter to accommodate one or more parallel tubes without disturbing one another. Although it has been found an advatage to suspend a tube in the gas discharge chamber, the invention is not limited to such an arrangement.
• Process for hardening the interior surface of steel gun-barrels which comprises subjecting the portion of the interior surface of a gun-barrel which is contacted by the projectile to an electrical glow-discharge in a nitrogenous atmosphere to effect heating of the interior surface of the gun-barrel, substantially entirely by such glowdischarge, to a nitriding temperature and heavy bombardment of such surface, with nitrogen ions to enrich 4.
• the glow dis-' charge is produced by a permanently applied voltage on which there are superimposed periodic pulses of short duration of a voltage at least 10%higher than, and up to ten times, thepermanent voltage.
• a conducting wire is disposed axially within the gun-barrel and is connected to a source of electrical tension.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Organic Chemistry (AREA)
• Metallurgy (AREA)
• Mechanical Engineering (AREA)
• Materials Engineering (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Manufacturing & Machinery (AREA)
• Geology (AREA)
• Geochemistry & Mineralogy (AREA)
• General Life Sciences & Earth Sciences (AREA)
• Environmental & Geological Engineering (AREA)
• Life Sciences & Earth Sciences (AREA)
• Physics & Mathematics (AREA)
• Plasma & Fusion (AREA)
• Analytical Chemistry (AREA)
• General Engineering & Computer Science (AREA)
• Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
• Heat Treatment Of Articles (AREA)

Priority Applications (1)

Applications Claiming Priority (4)

Publications (1)

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Family Applications (2)

Family Applications After (1)

Country Status (7)

Cited By (14)

Families Citing this family (21)

Citations (4)

Family Cites Families (3)

• 1954
  • 1954-12-27 CH CH342980D patent/CH342980A/de unknown
• 1955
  • 1955-06-08 GB GB16429/55A patent/GB810802A/en not_active Expired
  • 1955-06-13 FR FR1126104D patent/FR1126104A/fr not_active Expired
  • 1955-09-14 US US534376A patent/US2946708A/en not_active Expired - Lifetime
  • 1955-12-23 DE DEE11740A patent/DE1141850B/de active Pending
• 1956
  • 1956-02-10 FR FR69955D patent/FR69955E/fr not_active Expired
  • 1956-03-27 GB GB9492/56A patent/GB828699A/en not_active Expired
  • 1956-11-23 US US624169A patent/US2916409A/en not_active Expired - Lifetime
  • 1956-12-17 LU LU34829A patent/LU34829A1/xx unknown
  • 1956-12-17 BE BE553492D patent/BE553492A/xx unknown

Patent Citations (4)

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