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
  • 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
  • C23C8/80—After-treatment
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
  • C25D5/18—Electroplating using modulated, pulsed or reversing current
• • 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
  • C23C8/08—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 only one element being applied
  • C23C8/20—Carburising
  • C23C8/22—Carburising of ferrous surfaces
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
  • C25D11/02—Anodisation
  • C25D11/024—Anodisation under pulsed or modulated current or potential
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
  • C25D11/02—Anodisation
  • C25D11/34—Anodisation of metals or alloys not provided for in groups C25D11/04 - C25D11/32
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
  • C25D5/34—Pretreatment of metallic surfaces to be electroplated
  • C25D5/36—Pretreatment of metallic surfaces to be electroplated of iron or steel
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
  • C25D5/627—Electroplating characterised by the visual appearance of the layers, e.g. colour, brightness or mat appearance
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D9/00—Electrolytic coating other than with metals
  • C25D9/04—Electrolytic coating other than with metals with inorganic materials
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
  • F16L19/00—Joints in which sealing surfaces are pressed together by means of a member, e.g. a swivel nut, screwed on or into one of the joint parts
  • F16L19/06—Joints in which sealing surfaces are pressed together by means of a member, e.g. a swivel nut, screwed on or into one of the joint parts in which radial clamping is obtained by wedging action on non-deformed pipe ends
  • F16L19/061—Joints in which sealing surfaces are pressed together by means of a member, e.g. a swivel nut, screwed on or into one of the joint parts in which radial clamping is obtained by wedging action on non-deformed pipe ends a pressure ring being arranged between the clamping ring and the threaded member or the connecting member
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
  • F16L2201/00—Special arrangements for pipe couplings
  • F16L2201/60—Identification or marking

Definitions

• a low temperature carburized stainless steel workpiece can be carburized to a wide spectrum of different intense colors by cleaning the workpiece so as to remove the porous oxide layer inherently formed during low temperature carburization and then subjecting the electropolished workpiece to alternating current electrolysis in an electrolysis bath which contains a metal having multiple valence states and which further is maintained at a neutral to slightly basic pH.
• FIG. 1 illustrates a prior art fitting in a finger tight position
• Fig. IA illustrates the fitting of Fig. IA in a tightened position
• Fig.2 is a schematic illustration of the waveform of the electrical current applied to the workpiece in accordance with one embodiment of the invention.
• Tube fittings are well known articles of commerce.
• the term "tube fitting” means any type of tube fitting, unless otherwise stated.
• tube fittings include, but are not limited to, ferrule type fittings, such as single ferrule fittings, two ferrule fittings, and fittings that include more than two ferrules, flared tube end fittings, and other types of fittings.
• ferrule type fittings are described, for example, in commonly assigned US Patent Nos. 3,103,373, 6,629,708, provisional application Serial No. US60/652.631 (attorney docket no. 22188/06884), and PCT application PCT/US06/03909 the disclosures of which are incorporated herein by reference in their entirety.
• a fitting is composed of various components including body sections, nuts, ferrules or "gripping rings,” and the like.
• a ferrule may be designed so that, during pull-up, it plastically deforms, or its leading edge bites into the conduit being joined, or both.
• a ferrule may also be designed so that , during pull- up, the ferrule does not bite into the conduit being joined.
• such fittings (and/or component parts thereof) are color coded electrolytically for easy identification by growing a colored oxide coating on one or more surfaces of the fitting or part thereof.
• tube fittings can be made from a wide variety of different metals
• fittings of particular interest are made from steels containing 5 to 50, preferably 10 to 40, wt.% Ni.
• Preferred alloys contain 10 to 40 wt.% Ni and 10 to 35 wt.% Cr.
• More preferred are the stainless steels, especially the AISI 300 and 400 series steels.
• Fittings made from such steels, and particularly from austenitic stainless steels find particular use in high purity piping systems, i.e., piping systems used for processing high purity liquids and gases. See, the above-noted U.S. Patent No. 6,547,888 Bl.
• Case hardening is a widely used industrial process for enhancing the surface hardness of metal articles.
• the workpiece is contacted with a carburizing gas at 1700° F (950° C) or above whereby carbon atoms diffuse into the article's surface.
• Hardening occurs through the formation of "carbide precipitates,” i.e., specific metal carbide compounds arranged in the form of discrete particles separate and apart from the metal matrix in which they are contained.
• Low temperature carburization produces a substantial amount of soot as an unwanted by-product.
• the amount of soot produced exceeds the amount of carbon taken up by the workpiece.
• the amount of soot created is often large enough to completely engulf adjacent parts, thereby forming an amalgamated mass of soot and carburized parts.
• this unwanted soot by-product is almost always removed from the workpiece such as by washing or the like prior to use.
• low temperature carburization also produces a heavy oxide film, at least when carbon monoxide is used as the carbon source.
• This heavy oxide film which typically has a color ranging from light gold to dark gold-brown, is considerably different from the coherent chromium oxide film which makes stainless steel corrosion-resistant in that it is thicker and not coherent; i.e., the heavy oxide film is relatively porous. Therefore, this film is also removed before use to uncover the workpiece's carburized surface, thereby producing a "surface-cleaned" carburized workpiece. See, commonly assigned WO 02/063195 A (22188/06303), the disclosure of which is also incorporated herein by reference.
• removing the heavy oxide film may be done mechanically. However, it is most often done by anodic electropolishing in which the workpiece is immersed in an aqueous acidic bath and subjected to a direct electrical current to cause oxidation and dissolution of the outermost metal surface layer of the workpiece and removal of the heavy oxide film attached thereto. See, for example, U.S. Patent No. 4,026,737, U.S. Patent No. 4,269,633, U.S. Patent No. 4,859,287 and U.S. Patent No. 4,620,882, which disclose similar electropolishing treatments used to clean native stainless steels in preparation for coloring by conventional stainless steel electrolysis coloring processes.
• Electropolishi ⁇ g of native stainless steels is normally done to remove a substantial proportion and preferably all of the so-called "Bilby layer,” which is the surface layer of the native stainless steel containing contaminants as well as fracture grains. This layer is about 2.5 microns thick, and so electropolishing here is normally accomplished to remove at least this 2.5 micron surface layer and perhaps more.
• electropolishing low temperature carburized stainless steel is carried out to remove a minimum amount of the workpiece's metal surface, only about 1 micron or so.
• the hardened "case" produced by low temperature carburization only extends down to the first 10-25 microns or so of the workpiece's surface and, moreover, most of the diffused carbon which forms this hardened case is located at or near the workpiece's outer surface. Therefore electropolishing of low temperature carburized stainless steel is normally carried out to remove only a minimum amount of the workpiece's metal surface, so that the carburized surface layer of the workpiece is left largely intact.
• electropolishing is preferred over other techniques for removing this heavy oxide layer such as mechanical polishing or the like, since electropolishing avoids removing too much of the workpiece's surface layer.
• the low temperature carburized workpiece is ready for use as is.
• the workpiece can be subjected to still additional, optional processing steps.
• a low temperature carburized stainless steel workpiece which has been electropolished for removing the heavy oxide film formed during low temperature carburization is colorized by subjecting the workpiece to alternating current electrolysis in an electrolysis bath which contains a metal having multiple valence states and which is maintained at a neutral to slightly basic pH.
• the workpiece can take a wide variety of different forms.
• the workpiece may be a fitting component, including but not limited to a fitting body, a nut, a ferrule, a gripping ring, etc.
• a fitting component including but not limited to a fitting body, a nut, a ferrule, a gripping ring, etc.
• FIGS. 1 and IA which taken from U.S. Patent No. 6,629,708, the disclosure of which is incorporated herein by reference in its entirety.
• the workpiece may be any one or more of the components of the fitting illustrated by FIGS. 1 and IA.
• the workpiece is not limited to the components of the fitting shown in FIGS 1 and IA and may be a component of any type of fitting or a stainless steel part of any type of assembly.
• FIG. 1 shows the fitting components in a finger tight position preparatory to final tightening
• FIG. IA shows the fitting after final tightening
• the fitting comprises a body 10 having a cylindrical opening 12 counterbored for receiving tube end 13.
• a tapered, frusto-conical camming mouth 14 is located at the axial outer end of the counterbore.
• a front ferrule 16 having a smooth, cylindrical inner wall 18 is closely received on the tube.
• the front ferrule has a frusto-conical outer surface 20 to be received in the camming mouth.
• a rear ferrule 22 Associated with the front ferrule 16 and located axially outward therefrom is a rear ferrule 22 configured as shown with a tapered nose portion 24 and a rear flange 26 having an inclined end surface 28.
• the inclined end surface of the rear ferrule 22 provides a radial component as well as an axial component of the pull-up forces acting on the end surface as will be apparent to those skilled in the art.
• the tapered nose 24 enters a tapered camming surface in the rear surface of the front ferrule.
• the electrolysis bath used for the inventive coloring process contains ions of a metal having multiple valence states such as chromium, molybdenum, tungsten, manganese and vanadium.
• ions of a metal having multiple valence states such as chromium, molybdenum, tungsten, manganese and vanadium.
• Specific examples of such ions include chromates, molybdates, tungstates, manganates and vanadates, for example, Cr +6 , CrO 4 "2 , MOO3 "2 , MnO 4 "2 , V +5 , VO 3 " (metavanadate), V 2 O 7 "4 (pyrovanadate), and VO "4 (ortho vanadate). Mixtures of these ions can also be used.
• Specific compounds which can be used to supply such ions include, but are not limited to, ammonium dichromate, ammonium molybdate, ammonium metatungstate, lithium molybdate, sodium molybdate, sodium vanadate, sodium manganate and the like.
• concentration of the multivalent metal ion can vary widely, and any concentration can be used which will give the desired result. In general, concentrations ranging from about 0.01 to 1.0 moles/liter, more typically about 0.05 to 0.5 moles/liter, or even about 0.1 to 0.3 moles/liter, have been found to be useful.
• the pH of the electrolysis bath used in the inventive process is normally maintained between about 5-12, more typically about 6-11 or even 7-10. This represents a significant departure from prior electrolytic processes for coloring stainless steel in which the electrolysis baths are maintained at strongly acidic or strongly basic pH's through the addition of strong acids such as sulfuric acid or nitric acid, or strong bases such as sodium hydroxide. Such pH adjusters are not normally used in the electrolysis baths of the present invention and, indeed, are preferably avoided.
• an electropolished low temperature carburized stainless steel workpiece is colorized by subjecting the workpiece to alternating current electrolysis in an electrolysis bath as described above. This is done by alternating the polarity of the electrical current applied to the workpiece in a similar manner to that described in the above-noted U.S. Patent No. 4,859,287. Preferably this is done so that a plot of current density versus time assumes a generally rectangular wave form. Most preferably, this is done so that equal amounts of electrical current are applied in both parts of each cycle as illustrated, for example, in the waveform of Fig. 2 of this disclosure.
• equal means that the absolute amount of electrical current applied per unit of surface area of the part being colorized in the positive pulse of each cycle, as determined by integrating its current density/time waveform, is equal to the absolute amount of electrical current applied per unit of surface area in the negative pulse of each cycle.
• the magnitude and duration of the applied electrical current varies depending on the composition of the electrolysis bath and can easily be determined by routine experimentation in light of the working examples presented below.
• the magnitude of the applied current in terms of current density, should generally be between about 0.01 to 3 A/in 2 . This means that the current density in each positive pulse should be between about +0.01 and +3 A /in 2 , while the current density in each negative pulse should be between about -0.01 and -3 /in 2 . More typically, the magnitude of the applied current will be between about 0.02 to 1 A/in 2 or even about 0.03 to 0.7 A/in 2 .
• each pulse should normally be about 15- 1000 milliseconds, more commonly about 50-500 milliseconds, or even 75-200 milliseconds. Pulses lasting about 100 milliseconds have been found to be especially convenient, although pulses lasting less than 15 and more than 1000 milliseconds can also be used.
• Fig. 2 shows that the duration 12 of positive pulse 14 is equal to the duration 16 of negative pulse 18, the magnitude 20 of positive pulse 14 is equal to the magnitude 22 of negative pulse 18, and no delay is inserted between adjacent positive and negative pulses.
• a delay (where the workpiece is held at zero potential) can be inserted between successive positive and negative pulses.
• the magnitude and duration of the positive and negative pulses can be varied from cycle to cycle.
• the magnitude and duration of the positive pulse can be different from the magnitude and duration of the negative pulse in a particular cycle, provided that the absolute amounts of electrical current supplied in both pulses is essentially equal, as indicated above.
• additional positive and negative pulses can be included in the pattern of electrical current provided as described in col. 9, lines 9-28 of the above-noted U.S. Patent No. 4,859,287, so long as the last applied electric current is an alternating current or negative pulse current as described there.
• stainless steel ferrules made from AISI 316 stainless steel were low temperature carburized in general accordance with the above-noted U.S. Patent No. 6,547,888 Bl. After washing to remove the soot produced during carburization, the ferrules were electropolished to remove the heavy oxide coating that had also formed during carburization. The electropolished ferrules were then tumbled for 8 minutes in the presence of detergents, burnishing compounds and tumbling media for enhancing surface smoothness and then rinsed with water and dried, thereby producing electropolished ferrules each having a surface area of about 0.63 in 2 .
• the electropolished ferrules so obtained were then colorized by an electrolytic coloring process in accordance with the invention. This was done by subjecting the ferrules, which were mounted on a titanium anode, to alternating current electrolysis using an aqueous electrolysis bath containing 0.15M Na 2 MoC ⁇ . The pH of the electrolysis bath was approximately 9.5, which was due solely to the Na 2 MoO 4 , no additional acid or base being present. Electrolysis was carried out using alternating pulses of positive and negative current, each pulse lasting 100 milliseconds with no delays between the pulses. Ten different experiments were conducted at different current densities ranging from 0.033-0.13 A/in 2 . Each experiment lasted about 22 minutes, with the color of the ferrules obtained being monitored and recorded each minute.
• Tl Transition No. 1 constituting a reddish/blue rainbow effect
• T2 Transition No. 2 constituting a greenish/gold rainbow effect
• T3 Transition No. 3 constituting a bluish/gold rainbow effect
• T4 Transition No. 4 constituting a gold/pinkish red rainbow effect
• T5 Transition No. 5 constituting a pinkish red /green rainbow effect

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Organic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Electrochemistry (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Inorganic Chemistry (AREA)
• Heat Treatment Of Articles (AREA)
• Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
• Chemical Treatment Of Metals (AREA)
• Electrical Discharge Machining, Electrochemical Machining, And Combined Machining (AREA)

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• 2007
  • 2007-02-01 CA CA002640937A patent/CA2640937A1/en not_active Abandoned
  • 2007-02-01 CN CNA2007800054071A patent/CN101384754A/zh active Pending
  • 2007-02-01 JP JP2008555258A patent/JP2009526914A/ja not_active Withdrawn
  • 2007-02-01 WO PCT/US2007/002751 patent/WO2007108865A1/en active Application Filing
  • 2007-02-01 EP EP07749705A patent/EP1984542A1/en not_active Withdrawn
  • 2007-02-01 US US11/701,050 patent/US20070209948A1/en not_active Abandoned
  • 2007-02-01 KR KR1020087019522A patent/KR20080110991A/ko not_active Application Discontinuation
  • 2007-02-01 AU AU2007227773A patent/AU2007227773A1/en not_active Abandoned
• 2008
  • 2008-07-16 IL IL192838A patent/IL192838A0/en unknown

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