EP1146523A2 - Koaxialkabel mit schwarzem Oxid und zugehöriges Herstellungsverfahren - Google Patents

Koaxialkabel mit schwarzem Oxid und zugehöriges Herstellungsverfahren Download PDF

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Publication number
EP1146523A2
EP1146523A2 EP01303110A EP01303110A EP1146523A2 EP 1146523 A2 EP1146523 A2 EP 1146523A2 EP 01303110 A EP01303110 A EP 01303110A EP 01303110 A EP01303110 A EP 01303110A EP 1146523 A2 EP1146523 A2 EP 1146523A2
Authority
EP
European Patent Office
Prior art keywords
coaxial cable
stainless steel
furnace
sheath
chromium
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.)
Granted
Application number
EP01303110A
Other languages
English (en)
French (fr)
Other versions
EP1146523A3 (de
EP1146523B1 (de
Inventor
Farzad Kialashaki
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.)
Whittaker Corp
Original Assignee
Whittaker Corp
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
Application filed by Whittaker Corp filed Critical Whittaker Corp
Publication of EP1146523A2 publication Critical patent/EP1146523A2/de
Publication of EP1146523A3 publication Critical patent/EP1146523A3/de
Application granted granted Critical
Publication of EP1146523B1 publication Critical patent/EP1146523B1/de
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01BCABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B11/00Communication cables or conductors
    • H01B11/18Coaxial cables; Analogous cables having more than one inner conductor within a common outer conductor
    • H01B11/1882Special measures in order to improve the refrigeration
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01BCABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B11/00Communication cables or conductors
    • H01B11/18Coaxial cables; Analogous cables having more than one inner conductor within a common outer conductor
    • H01B11/1808Construction of the conductors
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01BCABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B13/00Apparatus or processes specially adapted for manufacturing conductors or cables
    • H01B13/22Sheathing; Armouring; Screening; Applying other protective layers
    • H01B13/225Screening coaxial cables

Definitions

  • the present invention generally relates to coaxial cables and more particularly to a stainless-steel-sheathed coaxial cable -having a black oxide surface coating and to a method of making the same.
  • black body A substance that absorbs all the radiation of any wavelength falling upon it is known as a black body. Such a body will emit the maximum intensity of radiation for any given temperature.
  • Blackbody surfaces with high emissivity have been used for heat radiation, since no other surface can emit more heat radiation. Such surfaces are in great demand for space applications for coaxial and waveguide transmission lines. In addition to their radiative properties, blackbody surfaces are used as electrostatic discharge bleed-off paths.
  • Conventional methods of preparing the external surfaces of transmission lines for blackbody radiation comprise either chemically glazing or ceramically coating the surface.
  • Chemical glazing is usually carried out by first cleaning the surface to be coated, then applying a primer to .the surface and thereafter coating the surface with a black paint.
  • Ceramic coating is usually carried out by applying a ceramic material such as silicon carbide to the surface.
  • the ceramic coating method results in a hard brittle surface coating which cannot be flexed or bent. This problem limits handling and use of the ceramic coated product. Such product is also subject to damage due to flight-induced vibration in space applications. Moreover, the ceramic coating method is very costly and time consuming.
  • the coating should also be flexible and abrasion resistant.
  • the present invention provides a cable and a method as defined in claims 1 and 6 respectively. Preferred features of embodiments of the invention are set out in the dependent claims.
  • the method comprises passing an assembled coaxial cable of a specific type through a treating furnace under selected conditions.
  • the cable has a metallic core conductor surrounded by a dielectric capable of resisting degradation at a temperature of at least about 1000 degrees C., preferably about 1000-1100 degrees C.
  • the dielectric and core are surrounded by a stainless steel sheath having a chromium content of at least about 18 weight percent, preferably about 18-20 weight percent, with essentially the remainder of the stainless steel being iron.
  • the cable is treated in the furnace in a hydrogen-free, wet nitrogen atmosphere at at least about 1000 degrees C., preferably 1000-1100 degrees C., which is a temperature which does not degrade the dielectric.
  • the residence time in the furnace is sufficient to form the desired blackbody coating in the form of a black oxide layer on the exterior surface of the stainless steel sheath.
  • the residence time is usually from about two to about five minutes.
  • the wet nitrogen is introduced into the furnace from a storage container where it is maintained at a pressure of about 20 p.s.i.
  • the nitrogen is bubbled through a water chamber and mixed with air prior to introduction into the furnace.
  • the treated black oxide layer-containing coaxial cable is then passed from the furnace and cooled to ambient temperature.
  • the black oxide layer is adherent to the underlying surface of the stainless steel sheath and is relatively thin and flexible, but also is abrasion resistant and thermally stable at high temperatures and in normally corrosive atmospheres. It comprises chromium oxide, preferably as chromic oxide.
  • the remainder of the black oxide layer essentially comprises iron oxide. It has an emissivity value which is close to that exhibited by the previously known chemical glazing and ceramic coatings.
  • elongated, semi-flexible, generally tubular coaxial cable 10 which comprises a central metallic transmission wire 12 running the length thereof and completely surrounded by a dielectric component 14, such as silicon dioxide, having suitable electrical characteristics, as well as a resistance to thermal degradation at up to at least about 1000 degrees C. and preferably up to about 1100 degrees C.
  • Dielectric component 14 is completely surrounded by an outer tubular sheath 16 of stainless steel having a chromium content of at least about 18 weight percent, preferably about 18-20 weight percent or more.
  • the remainder of the stainless steel is iron, with preferably not more than minor quantities of other metals.
  • Wire 12, dielectric component 14 and sheath 16 form an assembled coaxial cable 18 which is passed into, and heat treated in, the furnace employed in the present method to form coaxial cable 10 which, after treatment in accordance with the present method, includes an adherent blackbody on the exterior surface 20 of sheath 16 in the form of a black oxide layer 22 comprising chromium oxide, which may also contain iron oxide.
  • the chromium oxide may be in the form of chromic oxide.
  • FIG. 2 shows a furnace 24, such as a Watkins-Johnson conventional belt furnace having an input end 26 and an opposite output end 28 through which coaxial cable 18 is drawn by a wire (not shown) in order to form the desired black oxide layer on cable 18 which then becomes cable 10.
  • cable 18 is shown passing from a cable input reel 30 and cable straightener 32 upstream from furnace 24 to and through furnace 24 and downstream thereof to a cable take-up reel 34 as cable 10 after production of the black oxide layer 22 thereon.
  • cable 18 is subjected to a black-oxide-forming temperature of at least about 1000 degrees C. in a hydrogen-free, wet nitrogen atmosphere.
  • the wet nitrogen atmosphere as used in the present method is achieved by drawing nitrogen from storage containers where it is maintained at a pressure of about 20 p.s.i. and bubbling it through a water chamber before introduction into the furnace 24. In the furnace, the wet nitrogen is intermixed with air to some extent, since both ends of the furnace are open to atmosphere.
  • the residence time of cable 18 while in furnace 24 will vary, depending on the actual temperature employed in the furnace and the thickness of layer 22 which is desired, and also the concentration of chromium in sheath 16. However, normally the residence time for cable 18 in furnace 24 is from about two to about five minutes, resulting from a transit speed of either one foot per minute or two feet per minute through a furnace hot zone of approximately four to five feet in length.
  • stainless steel with a larger concentration than 20 weight percent of chromium for example, up to 36 weight percent or more, can be successfully employed in the present method, such stainless steel is normally more expensive and less flexible than stainless steel having 18-20 weight percent of chromium and may require a longer residence time in furnace 24 to fully develop the black oxide layer 22 thereon. Therefore, for most purposes stainless steel with 18-20 weight percent chromium is employed in the present method.
  • Cable 10 which is the patentable product produced by the present method, has suitable blackbody characteristics, including an emissivity value which is not less than 0.7, due to black oxide layer 22.
  • Layer 22 is tenaciously adherent to sheath 16 and is thermally stable at elevated temperatures. It also has sufficient flexibility so that cable 10 substantially retains its semi-flexible character and therefore can be rolled up on take-up reel 34 and successfully employed in a number of applications, including space applications. Cable 10 therefore has superior properties when compared to conventional coaxial cables, particularly in applications where high heat emissivity is desired.
  • Stainless steel 304L has the following concentrations, by weight percent of constituents: chromium -- 18-20; carbon -- 0.03; manganese -- 2 max.; nickel -- 8-12; phosphorus -- 0.045 max.; silicon -- 1 max; sulfur -- 0.03 max; remainder -- iron.
  • the furnace is a Watkins/Johnson belt furnace utilizing the auxiliary equipment set forth in FIG. 2 of the drawings, and in which the treating conditions are as follows:
  • the black oxide layer formed on the exterior of the stainless steel sheath comprises chromium oxide, substantially the remainder of said layer being iron oxide.
  • the layer is uniform, adherent, flexible and temperature stable at temperatures up to at least 900° F.
  • the finished coaxial cable therefore has superior blackbody properties.
  • a coaxial cable substantially identical to the coaxial cable of Example I is used, except that the stainless steel sheath has a chromium concentration of about 36 weight percent.
  • the treating conditions in the furnace of Example I are the same as in Example I, except as follows:
  • the finished treated cable has the same characteristics as the finished treated cable of Example I, except for a somewhat decreased flexibility for the black oxide layer and the sheath, and except for the fact that the black oxide layer is essentially chromium oxide.
  • Example III The coaxial cable being heat treated in Example III is the same as that of Example I and the treating conditions in the furnace are the same as in Example I, except as follows:
  • the finished cable containing the black oxide layer thereon has substantially the same characteristics as the finished cable of Example I.

Landscapes

  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Insulated Conductors (AREA)
  • Heat Treatment Of Strip Materials And Filament Materials (AREA)
  • Communication Cables (AREA)
EP01303110A 2000-03-31 2001-04-02 Koaxialkabel mit schwarzem Oxid und zugehöriges Herstellungsverfahren Expired - Lifetime EP1146523B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US54103700A 2000-03-31 2000-03-31
US541037 2000-03-31

Publications (3)

Publication Number Publication Date
EP1146523A2 true EP1146523A2 (de) 2001-10-17
EP1146523A3 EP1146523A3 (de) 2002-02-13
EP1146523B1 EP1146523B1 (de) 2004-09-22

Family

ID=24157938

Family Applications (1)

Application Number Title Priority Date Filing Date
EP01303110A Expired - Lifetime EP1146523B1 (de) 2000-03-31 2001-04-02 Koaxialkabel mit schwarzem Oxid und zugehöriges Herstellungsverfahren

Country Status (3)

Country Link
EP (1) EP1146523B1 (de)
AT (1) ATE277413T1 (de)
DE (1) DE60105683D1 (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2909217A1 (fr) * 2006-11-29 2008-05-30 Commissariat Energie Atomique Cable electrique a haute immunite electro-magnetique a isolant mineral et procede de fabrication de celui-ci

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110783679B (zh) * 2019-11-01 2021-06-01 中国电子科技集团公司第三十八研究所 一种硅基单通道传输结构、同轴阵列传输结构及加工方法

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3892969A (en) * 1974-04-05 1975-07-01 Babcock & Wilcox Co Neutron detector with gamma compensated cable
US5646372A (en) * 1994-09-27 1997-07-08 Hitachi Cable Ltd. Metal tube and electric cable using the same

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3892969A (en) * 1974-04-05 1975-07-01 Babcock & Wilcox Co Neutron detector with gamma compensated cable
US5646372A (en) * 1994-09-27 1997-07-08 Hitachi Cable Ltd. Metal tube and electric cable using the same

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2909217A1 (fr) * 2006-11-29 2008-05-30 Commissariat Energie Atomique Cable electrique a haute immunite electro-magnetique a isolant mineral et procede de fabrication de celui-ci

Also Published As

Publication number Publication date
ATE277413T1 (de) 2004-10-15
EP1146523A3 (de) 2002-02-13
DE60105683D1 (de) 2004-10-28
EP1146523B1 (de) 2004-09-22

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