EP1192295A1 - Article exhibiting improved resistance to formicary corrosion - Google Patents
Article exhibiting improved resistance to formicary corrosionInfo
- Publication number
- EP1192295A1 EP1192295A1 EP00930472A EP00930472A EP1192295A1 EP 1192295 A1 EP1192295 A1 EP 1192295A1 EP 00930472 A EP00930472 A EP 00930472A EP 00930472 A EP00930472 A EP 00930472A EP 1192295 A1 EP1192295 A1 EP 1192295A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- coating
- copper
- corrosion
- further characterized
- formicary
- 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
Links
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
- C23C30/00—Coating with metallic material characterised only by the composition of the metallic material, i.e. not characterised by the coating process
Definitions
- This invention relates generally to protecting metals from a corrosive environment, and more specifically, to protecting copper from formicary corrosion when used in a corrosive environment.
- Corrosion is a process that involves two simultaneous reactions which are called half- cells.
- One half-cell reaction is the oxidation or corrosion ofthe metal. This process involves the loss of electrons, e.g.,
- Electrons from the oxidation process are in turn used by an associated reduction half- cell reaction, which is often the reduction of oxygen or hydrogen, e.g.,
- the oxidation reaction (corrosion process) can only proceed at a rate governed by the reduction reaction that uses the electrons from the oxidation process. This is because charge neutrality must be maintained.
- Prevention of this form of corrosion has typically been accomplished by elimination at least one of the three necessary constituents for its occurrence, i.e., air, moisture, or organic acid. However, when at least one of these constituents cannot be removed, as would be the case in an indoor air conditioning application in which an evaporator coil is wet by condensate by virtue of its dehumidification function, alternate protection methods are needed.
- the primary object of this invention is to provide an article, such as the copper tubes of an evaporator coil, having improved formicary corrosion resistant properties when used in a corrosive environment.
- Another object of this invention is to provide a copper article having a coating for inhibiting corrosive activities due to formicary corrosion.
- Yet another object of this invention is to provide an article formed from copper and having a tin or tin alloy coating for inhibiting formicary corrosion.
- the article of the present invention including a copper member having a surface and a coating on the surface for preventing formicary corrosion ofthe copper member.
- the article is a copper tube and the coating formed from one of tin and a tin alloy.
- the coating has a thickness in the range of 0.10 to 1.00 mil and is uniformly applied to the surface. Most preferably, the thickness ofthe coating is 0.50 mil.
- FIG. 1 is a perspective view of an evaporator coil incorporating copper tubing treated in accordance with the principles ofthe present invention
- FIG. 2 is a graph illustrating the performance improvements achieved in accordance with the principles ofthe present invention.
- the present invention provides for formicary corrosion protection of copper, such as copper tubing used in plate-fin coils.
- copper such as copper tubing used in plate-fin coils.
- the present invention is not limited to this specific example and could be used in connection with a number of arrangements where copper members are used in a corrosive environment.
- FIG. 1 illustrates a plate-fin coil 1 ofthe type typically used in air conditioning units.
- the coil includes one or more flow circuits for carrying refrigerant therethrough.
- the coil 1 contains a single flow circuit tube 2 consisting of an inlet line 3 and an outlet line 4, and a plurality of fins 5 extending radially therefrom.
- evaporator coils of this type are commonly used in corrosive environments.
- coils of this type are fabricated utilizing copper tubing for the circuit flow tubes. Copper is utilized in tube construction because of its good heat transfer properties, general resistance to corrosion, and ease of fabrication and repair.
- the exposed surface ofthe copper tube 2 is coated or enriched with a material for preventing formicary corrosion.
- Tin and tin alloys are the best candidates for this material.
- substantial improvements in the resistance to formicary corrosion is achieved by coating or impregnating the copper tubing's surface with a layer of material such as tin or tin alloy.
- FIG. 2 The improvement achieved using the principles ofthe present invention is illustrated graphically in FIG. 2.
- Testing has shown a greater than twenty fold (20x) improvement in the failure rate of copper when, for example, copper tubing is coated with 0.5 mil of electroplated tin.
- Other methods of prevention such as using formicary corrosion inhibitors (not including removing one ofthe three factors causing formicary corrosion which is rarely a feasible option), typically show only a three fold (3x) improvement. Accordingly, by coating the formicary-corrosion- susceptible copper tubing with a metal that is resistant to such corrosion, the corrosion resistance ofthe copper tubing is significantly improved.
- tin alloys containing such metals as zinc, magnesium, copper, gallium, cadmium and lead will also result in improved resistance to formicary corrosion ofthe copper.
- Other metals also increasing the resistance to formicary corrosion may be used as well.
- the coating or surface enrichment ofthe copper tubes 2, in the embodiment illustrated, with tin or other discussed material is accomplished prior to the assembly ofthe heat exchanger 10.
- Potential methods include: (1) hot dipping, (2) electroplating (3) vapor deposition, and (4) ion implantation.
- This invention includes all coatings that work to prevent formicary corrosion of copper.
- the proposed approach is very cost effective and maintains the thermal conduction ofthe copper tubing in heat exchanger applications.
- High thermal conduction is accomplished by using a coating with a relatively high thermal conductivity or by applying very thin coatings.
- An important aspect ofthe present invention is the production of a uniform coating of formicary corrosion reaction resistant material over the entire exterior surface ofthe flow circuit tubes 2. Regardless ofthe process used, the variables of tube surface preparation, tube preheat temperature, coating composition, and coating thickness need to be carefully controlled to achieve the proper results ofthe present invention.
- the preparation ofthe exposed surfaces ofthe tube is designed to remove the surface oxide layer from the copper to ensure that the coating material will adhere well to the tube.
- a number of surface preparation processes are known in industry and include the use of acid reducing gases, fluxes and mechanical abrasion such as shot blasting It is preferred that the coating have high ductility to allow for the subsequent assembly ofthe heat exchanger without damaging the coating. The ductility ofthe coating is determined in part by the coating composition and the thickness ofthe coating.
- the coating must be thick enough to prevent the penetration ofthe electrolyte, and thin enough to have good formability and cost benefits.
- the optimal range of thickness is 0.10 mils to 1.0 mils.
- an article is provided, such as a plate- fin heat exchanger coil, having improved formicary corrosion resistant properties when used in a corrosive environment.
- a copper tube evaporator is provided having a coating for inhibiting corrosion activities due to formicary corrosion.
- a plate-fin coil is provided formed from copper tubing with a tin or tin alloy coating for inhibiting formicary corrosion.
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Preventing Corrosion Or Incrustation Of Metals (AREA)
- Physical Vapour Deposition (AREA)
Abstract
Description
Claims
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US32422399A | 1999-06-01 | 1999-06-01 | |
US324223 | 1999-06-01 | ||
PCT/US2000/012541 WO2000073537A1 (en) | 1999-06-01 | 2000-05-08 | Article exhibiting improved resistance to formicary corrosion |
Publications (2)
Publication Number | Publication Date |
---|---|
EP1192295A1 true EP1192295A1 (en) | 2002-04-03 |
EP1192295B1 EP1192295B1 (en) | 2005-11-16 |
Family
ID=23262638
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP00930472A Expired - Lifetime EP1192295B1 (en) | 1999-06-01 | 2000-05-08 | Article exhibiting improved resistance to formicary corrosion |
Country Status (4)
Country | Link |
---|---|
EP (1) | EP1192295B1 (en) |
DE (1) | DE60024087T2 (en) |
ES (1) | ES2249268T3 (en) |
WO (1) | WO2000073537A1 (en) |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE602005026527D1 (en) * | 2004-05-05 | 2011-04-07 | Luvata Oy | HEAT TRANSFER TUBE MADE FROM TIN BRASS ALLOY |
CN105401177A (en) * | 2015-12-14 | 2016-03-16 | 广东美的暖通设备有限公司 | Anti-corrosion treatment method for heat exchanger, heat exchanger and air conditioner |
Family Cites Families (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS59229200A (en) * | 1983-06-08 | 1984-12-22 | Matsushita Electric Ind Co Ltd | Heat exchanger |
JPH07166270A (en) * | 1993-12-13 | 1995-06-27 | Mitsubishi Materials Corp | Copper alloy excellent in resistance to ant-lair-like corrosion |
JPH08178585A (en) * | 1994-12-27 | 1996-07-12 | Paloma Ind Ltd | Manufacture of heat exchanger |
JPH09296997A (en) * | 1996-05-01 | 1997-11-18 | Kobe Steel Ltd | Copper or copper alloy tube for heat exchanger |
-
2000
- 2000-05-08 WO PCT/US2000/012541 patent/WO2000073537A1/en active IP Right Grant
- 2000-05-08 EP EP00930472A patent/EP1192295B1/en not_active Expired - Lifetime
- 2000-05-08 DE DE60024087T patent/DE60024087T2/en not_active Expired - Lifetime
- 2000-05-08 ES ES00930472T patent/ES2249268T3/en not_active Expired - Lifetime
Non-Patent Citations (1)
Title |
---|
See references of WO0073537A1 * |
Also Published As
Publication number | Publication date |
---|---|
ES2249268T3 (en) | 2006-04-01 |
DE60024087D1 (en) | 2005-12-22 |
EP1192295B1 (en) | 2005-11-16 |
DE60024087T2 (en) | 2006-07-27 |
WO2000073537A1 (en) | 2000-12-07 |
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