US20190161830A1 - Highly corrosion resistant copper tube - Google Patents

Highly corrosion resistant copper tube Download PDF

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Publication number
US20190161830A1
US20190161830A1 US16/262,158 US201916262158A US2019161830A1 US 20190161830 A1 US20190161830 A1 US 20190161830A1 US 201916262158 A US201916262158 A US 201916262158A US 2019161830 A1 US2019161830 A1 US 2019161830A1
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US
United States
Prior art keywords
copper
tube
corrosion
copper tube
weight
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.)
Abandoned
Application number
US16/262,158
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English (en)
Inventor
Masaki Kumagai
Yoshihiko KYO
Saori MAE
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.)
Toyokawa Holdings Inc
UACJ Copper Tube Corp
Original Assignee
UACJ Corp
UACJ Copper Tube 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 UACJ Corp, UACJ Copper Tube Corp filed Critical UACJ Corp
Assigned to UACJ COPPER TUBE CORPORATION, UACJ CORPORATION reassignment UACJ COPPER TUBE CORPORATION ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: KUMAGAI, MASAKI, KYO, Yoshihiko, MAE, Saori
Publication of US20190161830A1 publication Critical patent/US20190161830A1/en
Assigned to TOYOKAWA HOLDINGS INC. reassignment TOYOKAWA HOLDINGS INC. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: UACJ CORPORATION
Abandoned legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C9/00—Alloys based on copper
    • 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
    • F16L9/00—Rigid pipes
    • F16L9/02—Rigid pipes of metal
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F21/00—Constructions of heat-exchange apparatus characterised by the selection of particular materials
    • F28F21/08—Constructions of heat-exchange apparatus characterised by the selection of particular materials of metal
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F21/00—Constructions of heat-exchange apparatus characterised by the selection of particular materials
    • F28F21/08—Constructions of heat-exchange apparatus characterised by the selection of particular materials of metal
    • F28F21/081—Heat exchange elements made from metals or metal alloys
    • F28F21/085—Heat exchange elements made from metals or metal alloys from copper or copper alloys

Definitions

  • the present invention relates to an improvement of a highly corrosion-resistant copper tube, and more particularly relates to a technique of improving corrosion resistance of the copper tube, which copper tube is suitably usable as a heat transfer tube and a refrigerant tube in air-conditioning equipment and refrigerating equipment, for example.
  • a refrigerant tube (tubes arranged inside desired equipment) and the like, which are used, for example, in air-conditioning equipment and refrigerating equipment, a tube made of a phosphorus (P)-deoxidized copper (JIS-H3300-C1220T) having excellent properties in terms of corrosion resistance, brazeability, heat conductivity and bending workability, for example, has been mainly used.
  • P phosphorus
  • JIS-H3300-C1220T phosphorus-deoxidized copper
  • ant nest corrosion or “formicary corrosion” which is an unusual corrosion that progresses in the form of an ants' nest from a surface of the tube in a direction of the wall thickness.
  • the ant nest corrosion is considered to be generated in a damp environment by a corrosive medium in the form of a lower carboxylic acid such as a formic acid and an acetic acid.
  • a chlorine-based organic solvent such as 1,1,1-trichloroethane, particular kinds of lubricating oil, and formaldehyde, for example.
  • JP6-122932A proposes a corrosion-resistant copper tube having a high strength, which tube includes 0.0025-0.01% by weight of P (phosphorus) and the balance being Cu (copper) and conventional impurities, or further has an oxygen content of not higher than 20 ppm by weight.
  • P phosphorus
  • Cu copper
  • conventional impurities or further has an oxygen content of not higher than 20 ppm by weight.
  • the technique aims to achieve a higher resistance to the ant nest corrosion than that of the conventional phosphorus-deoxidized copper tube by reducing the P content in the phosphorus-deoxidized copper tube, because the ant nest corrosion is suppressed in an oxygen-free copper tube containing an extremely small amount of P.
  • the above-described copper tube having a reduced amount of P and a low oxygen concentration does not have a sufficient degree of corrosion resistance. Specifically, it is difficult for the copper tube proposed in the above-described technique to exhibit the resistance to the ant nest corrosion for a long period of time.
  • WO2014/148127A1 proposes a highly corrosion-resistant copper tube formed of a copper material comprising 0.05-1.0% by weight of P and the balance consisting of Cu and inevitable impurities, and discloses that such a copper tube enjoys an improved resistance to the ant nest corrosion.
  • the copper tube having the improved resistance to the ant nest corrosion can be practically advantageously obtained by employing a tube material having a P content larger than that of the conventional tube material made of the phosphorus-deoxidized copper.
  • the present invention was made in view of the background art described above. It is therefore a technical problem of the invention to provide a highly corrosion-resistant copper tube which can exhibit a higher resistance to the ant nest corrosion for a long period of time, and which is suitably usable as a heat transfer tube and a refrigerant tube in air-conditioning equipment and refrigerating equipment. It is another problem of the invention to advantageously extend a service life of equipment produced by employing such a copper tube.
  • the inventors of the present invention made further intensive studies on the ant nest corrosion generated in the copper tube used in the air-conditioning equipment, the refrigerating equipment and the like, and found that an improved corrosion resistance of the copper tube can be further advantageously enjoyed for a long period of time by controlling an oxygen content within a specific range in a copper tube containing P in a ratio of 0.15-0.50% by weight.
  • the present invention was completed based on this finding.
  • the gist of the present invention is to provide a highly corrosion-resistant copper tube which is formed of a copper material comprising a copper alloy consisting of 0.15-0.50% by weight of phosphorus and the balance being copper and inevitable impurities, the copper material having an oxygen content of not higher than 30 ppm by weight.
  • a long-term corrosion resistance to the ant nest corrosion is further effectively improved by setting the oxygen content of the copper material to be not higher than 30 ppm by weight in the corrosion-resistant copper tube which is formed of the copper material comprising the copper alloy consisting of 0.15-0.50% by weight of phosphorus and the balance being copper and inevitable impurities.
  • the oxygen content of the copper material is not higher than 20 ppm by weight.
  • a total amount of the inevitable impurities is not higher than 0.05% by weight.
  • the copper tube is arranged in a damp environment and subjected to corrosion that progresses in the form of an ants' nest from a surface of the tube in a direction of a wall thickness of the tube by a corrosive medium in the form of a lower carboxylic acid.
  • the invention also provides a heat transfer tube and a refrigerant tube (tubes arranged inside desired equipment) in air-conditioning equipment or refrigerating equipment.
  • the present invention provides a method of improving a corrosion resistance of a copper tube against ant nest corrosion which is generated by a corrosive medium in the form of a lower carboxylic acid in a damp environment and progresses from a surface of the copper tube used for air-conditioning equipment or refrigerating equipment in the damp environment, wherein the copper tube is formed of a copper material comprising a copper alloy consisting of 0.15-0.50% by weight of phosphorus and the balance being copper and inevitable impurities, the copper material having an oxygen content of not higher than 30 ppm by weight.
  • a practically useful copper tube exhibiting an excellent corrosion resistance against the ant nest corrosion, which corrosion resistance is superior to that of the conventional copper tube and is effective for a long period of time, can be provided.
  • the copper tube as the heat transfer tube or the refrigerant tube (tubes arranged inside desired equipment), for example, which are used in the air-conditioning equipment or the refrigerating equipment, the service life of the equipment can be further advantageously improved.
  • FIG. 1 is a schematic cross sectional view showing an apparatus used for a corrosion resistance test of the tube in illustrated examples.
  • the present invention has a remarkable feature that a highly corrosion-resistant copper tube according to the invention is formed of a copper material which has a phosphorus (P) content held within a range of 0.15-0.50% by weight and has an oxygen content of not higher than 30 ppm by weight, so that the copper tube according to the invention is configured to have a concentration of P higher than that of the conventional copper tube and the oxygen content of not higher than 30 ppm by weight at the same time.
  • P phosphorus
  • the type of corrosion generated in the copper tube shifts from a localized corrosion which progresses from the surface of the tube in the vertical direction of the axis of the tube (a direction penetrating the thickness of the tube) to a uniform corrosion which progresses in the horizontal direction of the axis of the tube (a direction extending over the surface of the tube) even under a severer corrosive environment.
  • generation of the localized corrosion in the copper tube is effectively suppressed or prevented, and the copper tube can exhibit a corrosion resistance which is considerably higher than that of the conventional copper tube for a long period of time.
  • the P content of the copper tube is set so as to be not lower than 0.15% by weight, because where the P content of the copper tube is lower than 0.15% by weight, the ant nest corrosion, which is the above-described localized corrosion, is likely to be generated.
  • a P content of more than 0.50% by weight does not permit a substantially effective improvement in the resistance of the copper tube against the ant nest corrosion, and even causes deterioration of workability of the copper tube during production, thereby giving rise to a problem of cracking of the copper tube, for example.
  • the upper limit of the P content needs to be 0.50% by weight.
  • the above-described localized corrosion may be generated when it is exposed to a severer corrosive environment for a long period of time, even if the copper tube includes the predetermined amount of P.
  • the oxygen content needs to be not higher than 30 ppm by weight. It is preferable to set the oxygen content to be not higher than 20 ppm by weight in order to obtain the corrosion resistance effective for a long period of time under the severer corrosive environment.
  • the lower limit of the oxygen content is generally set to be not lower than 5 ppm by weight, preferably not lower than 7 ppm by weight, and more preferably not lower than 10 ppm by weight, to practically obtain the effective corrosion resistance.
  • the highly corrosion-resistant copper tube according to the invention is formed of a copper (Cu) material comprising a copper alloy consisting of the above-described amount of P and the oxygen, and the balance being Cu and inevitable impurities.
  • a total amount of the inevitable impurities such as Fe, Pb and Sn is generally controlled so as to be not more than 0.05% by weight.
  • a Cu molten metal is intercepted from the atmosphere during production of the Cu molten metal. More particularly, the Cu molten metal can be intercepted from the atmosphere as follows. When a Cu source material is melted, a cover is disposed over the top of a melting furnace, and a nitrogen gas is introduced into the inside of the cover to fill the melting furnace. Furthermore, a cover is disposed also over the Cu molten metal in a passage from the melting furnace to a casting site, and the nitrogen gas is introduced to fill the passage.
  • the oxygen content is advantageously reduced.
  • the copper tube according to the invention may have smooth (or non-grooved) inner and outer surfaces.
  • the heat transfer tube may advantageously have internal or external grooves of various shapes formed by various known internal or external working.
  • the refrigerant tube When the copper tube is employed as the refrigerant tube in the air-conditioning equipment and the refrigerating equipment, the refrigerant tube generally has smooth inner and outer surfaces.
  • various billets were produced, each of which billets has a composition having a P content and an oxygen content indicated in Table 1 given below and the balance consisting of Cu and inevitable impurities.
  • the billets were subjected to the conventional process including hot-extrusion to produce a tube and drawing of the tube, so that various copper tubes (Nos. 1 to 6) having an outer diameter of 9.52 mm and a thickness of 0.41 mm were obtained.
  • the obtained copper tubes were then subjected to an ant nest corrosion test described below.
  • the oxygen content of each of the billets was controlled by intercepting the Cu source material to provide the billet from the atmosphere, and suitably changing the form of the interception.
  • a copper tube No. 7 having a high degree of the oxygen content and a copper tube No. 10 having a high degree of the P content were provided. Furthermore, copper tubes Nos. 8 and 9 consisting of the phosphorus-deoxidized copper were provided. In production of the copper tubes Nos. 9 and 10, the Cu molten metal was intercepted from the atmosphere as in the above-described copper tubes Nos. 1-6. On the other hand, in production of the copper tubes Nos. 7 and 8, the Cu molten metal was not intercepted from the atmosphere, and the Cu molten metal in the melting furnace and in the passage from the melting furnace to the casting site was subjected to contact with the atmosphere. It is noted that the copper tube No. 10 was made of a Cu material containing an excessive amount of P, so that the tube suffered from deficiencies such as cracking during tube-making, and a copper tube to be subjected to the corrosion test could not be obtained. Thus, the desired corrosion test could not be conducted.
  • a reference numeral 2 represents a plastic container which has a capacity of 2 L and which can be hermetically sealed with a cap 4 .
  • Silicone plugs 6 are attached to the cap 4 such that the plugs 6 extend through the cap 4 .
  • Copper tubes 10 are inserted into the plastic container 2 by a predetermined length, such that the copper tubes 10 extend through the respective silicone plugs 6 .
  • Lower open ends of the copper tubes 10 are closed with silicone plugs 8 .
  • 100 mL of an aqueous formic acid solution having a predetermined concentration is accommodated in the plastic container 2 , such that the copper tubes 10 do not contact with the aqueous solution.
  • aqueous formic acid solutions 12 whose concentrations were respectively set to be 0.01%, 0.1% and 1%, were provided.
  • the copper tubes 10 were set in the plastic container 2 in which each kind of the aqueous formic acid solutions 12 was accommodated, and the plastic container 2 was left within a constant temperature bath at a temperature of 40° C.
  • the plastic container 2 with the copper tubes 10 was taken out of the bath and left for two hours at room temperature (15° C.) each day, to cause dewing on surfaces of the copper tubes 10 due to a difference between the temperature of the constant temperature bath and the room temperature.
  • the copper tubes 10 were subjected to the corrosion test under the above-described conditions for 80 days.
  • each of the copper tubes subjected to the corrosion test was examined with respect to the cross section of the tube. Then, each of the copper tubes was measured of the maximum corrosion depth from the outer surface in terms of the respective aqueous formic acid solutions with the different concentrations. The results are shown in the following Table 2.
  • the Comparative Example (copper tube No. 7) having the P content within the range of the invention and the oxygen content of 39 ppm by weight, which is higher than 30 ppm by weight, and the phosphorus-deoxidized copper tubes (copper tubes Nos. 8 and 9) having the P content outside the range of the invention suffered from a remarkable ant nest corrosion in the long-term ant nest corrosion test using the 0.1% and 1% aqueous formic acid solutions. It was recognized that the copper tubes of the Comparative Examples were inferior to the copper tubes Nos. 1-6 in terms of the corrosion resistance, and had problems in practical use.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Preventing Corrosion Or Incrustation Of Metals (AREA)
US16/262,158 2016-08-04 2019-01-30 Highly corrosion resistant copper tube Abandoned US20190161830A1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
JP2016153509 2016-08-04
JP2016-153509 2016-08-04
PCT/JP2017/015004 WO2018025451A1 (ja) 2016-08-04 2017-04-12 高耐食性銅管

Related Parent Applications (1)

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PCT/JP2017/015004 Continuation WO2018025451A1 (ja) 2016-08-04 2017-04-12 高耐食性銅管

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US20190161830A1 true US20190161830A1 (en) 2019-05-30

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Application Number Title Priority Date Filing Date
US16/262,158 Abandoned US20190161830A1 (en) 2016-08-04 2019-01-30 Highly corrosion resistant copper tube

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US (1) US20190161830A1 (ja)
EP (1) EP3495519A4 (ja)
JP (1) JP6912480B2 (ja)
WO (1) WO2018025451A1 (ja)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR101931478B1 (ko) * 2017-04-27 2018-12-20 가부시키가이샤 유에이씨제이 내개미집 형상 부식성이 우수한 동관
WO2019031191A1 (ja) * 2017-08-10 2019-02-14 株式会社Uacj 耐蟻の巣状腐食性銅管

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS61221344A (ja) * 1985-03-27 1986-10-01 Sumitomo Light Metal Ind Ltd 給水給湯配管用銅合金材料
JP2008255379A (ja) * 2007-03-30 2008-10-23 Kobelco & Materials Copper Tube Inc 熱交換器用銅合金管

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH06122932A (ja) * 1992-10-09 1994-05-06 Hitachi Cable Ltd 耐食性高強度銅管
JPH06192773A (ja) * 1992-10-27 1994-07-12 Kobe Steel Ltd 耐食性銅合金管
JPH07166276A (ja) * 1993-12-15 1995-06-27 Mitsubishi Materials Corp 耐蟻の巣状腐食性に優れた銅合金およびこの銅合金からなる熱交換器用配管
CN105143478B (zh) * 2013-03-19 2017-07-07 株式会社Uacj 高耐蚀性铜管
JP5990497B2 (ja) * 2013-07-01 2016-09-14 株式会社コベルコ マテリアル銅管 耐食性無酸素銅合金管
KR101911214B1 (ko) * 2016-09-29 2018-10-23 가부시키가이샤 유에이씨제이 고내식성 구리관

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS61221344A (ja) * 1985-03-27 1986-10-01 Sumitomo Light Metal Ind Ltd 給水給湯配管用銅合金材料
JP2008255379A (ja) * 2007-03-30 2008-10-23 Kobelco & Materials Copper Tube Inc 熱交換器用銅合金管

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Publication number Publication date
EP3495519A4 (en) 2019-12-25
JPWO2018025451A1 (ja) 2019-05-30
EP3495519A1 (en) 2019-06-12
JP6912480B2 (ja) 2021-08-04
WO2018025451A1 (ja) 2018-02-08

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