® The International Association, Ltd. Resistance can be found in SAE Paper Number CuproBraze (ICA) is the leading organization for the Electrochemical processes can be 2001-01-1718. promotion of the use of copper worldwide. This latest research The Association’s twenty-nine members extremely complicated and hence the represent about 80 percent of the world’s external and internal corrosion resistance Conclusion corroborates, clarifies ExecutiveReport refined copper output, and its six associate of Cu proBraze has been the These SAE papers can serve as a good members are among the world’s largest subject of much research in recent years. entrance point for accessing the broader copper and copper alloy fabricators. ICA is and amplifies more Number 19 responsible for guiding policy, strategy The most recent research is described in body of literature on their respective and funding of international initiatives a paper co-authored by Olof Forsén, who topics. and promotional activities. With headquar- is a Professor at the Laboratory of Taken together they provide an excel- than a decade of Research Confirms Advantages of ters in New York City, ICA operates in 28 Corrosion and Materials Chemistry, lent foundation for a comprehensive worldwide locations through a network intense CuproBraze of regional offices and copper develop- Helsinki University of Technology. understanding Cu proBraze materials and CuproBraze Technology ment associations. Brazed aluminum radiators were manufacturing processes. included in this study of four different Reprints can be ordered (and PDF-files development. everal new technical papers about December 2000 and is now available in types of accelerated corrosion tests. The can be downloaded) by visiting the SAE the underlying materials science the SAE Technical Paper Series (2000- S governing the properties and use 01-3456). conclusion is that the corrosion resis- Web site (www.sae.org) or by calling tance of proBraze radiators is clearly SAE customer service at 1-877-606-7323 of CuproBraze alloys have been published This vital reference lists all of the important For additional information Cu better than that of soldered copper/ (North America) or 1-724-776-4970 this past year. physical properties of copper and aluminum about the CuproBraze process radiators and very competitive with that (International) from 8 a.m. to 5 p.m. This latest research corroborates, clarifies side-by-side, making a compelling case in or ICA’s CuproBraze consulting of brazed aluminum radiators. Details Eastern Time. and amplifies more than a decade favor of the use Cu proBraze alloys in services, please contact the of intense research, which began in the mobile heat exchanger technology. early nineties and led to the introduction Briefly, the greater strength and ther- International Copper Association of a new class of copper and brass mate- mal conductivity of copper and brass com- at [email protected]. Recently Published SAE Papers on Cu proBraze Research rials for heat exchanger applications. pensate for their higher compared to aluminum. Other properties such as SAE Paper Number Title The State of the Technology , specific heat, melting 2001-01-1726 Interactions between the materials in the tube-fin-joints in A concise “state of the technology” point, energy consumption, corrosion brazed copper-brass heat exchangers address was presented by Johan Scheel resistance and reparability favor the copper and Bengt Gustafsson at the and alloys for radiators and heat exchangers. Bus Meeting and Exposition in When manufacturing processes are 2001-01-1718 External Corrosion Resistance of CuproBraze® Radiators

The microstructure of the joint between the anneal-resistant 2001-01-1754 Electrochemical Tests with Copper / Brass Tube Materials in Coolants. copper fin and the anneal- resistant brass tube shows that alloying does not influence 01HX-18 OCP – Materials the heat performance of the heat exchanger.

01HX-19 CuproBraze Manufacturing – Plant Design – Lock Seam Tubes

2000-01-3456 CuproBraze Mobile Heat Exchanger Technology

International Copper Association, Ltd. 260 Madison Avenue, 16th Floor, New York, NY 10016-2401 Tel: 212.251.7240, Fax: 212.251.7245 The new facility in Västerås, with a binder to form a brazing paste. between the materials in the tubes, fins Sweden is a center for CuproBraze The special attributes of this brazing pow- and joints. research and development activities. der are its relatively low melting point, Extensive testing was performed on its compatibility with fin and tube materials fin-tube joints prepared in a laboratory and its compatibility with existing man- . The purpose of this testing was ufacturing processes. to measure the degree of interaction of Together these three alloys enable the the joining material with the alloys of CuproBraze processes for the manufacture the fin and tubes. The high copper of heat exchangers. A companion The times above 600 ºC (melting paper (01HX-19) by the same authors of the brazing materials) content of the tubes (Falkenö and Ainali) describes the and the maximum temperature were differences in manufacturing processes varied over a wide range of values, and contributes to improved between conventional soft- then the amount of alloying with the fin process and Cu proBraze. and tube was measured by examining resistance against stress Data is also given comparing the corro- the microstructure of the joints. sion potentials of the fin, tube and joint The paper even gives a section of the corrosion cracking and materials. These three different materials ternary Cu-Sn-P phase diagram with 15 exhibit nearly identical corrosion poten- percent , as part of the discussion of tials; the absence of galvanic differences the interactions between the fin and dezincification. explains the exceptional resistance of joint materials. CuproBraze heat exchangers against The conclusion of the paper is that bimetallic corrosion. some alloying does occur but that the process can be controlled and optimally considered, Cu proBraze technology precipitates form in the fin alloy. Since emerges as a winner. heat conductivity closely tracks electrical Interaction between Materials adjusted so this alloying does not conductivity, this copper alloy is well Those interested in probing even deeper influence the heat performance of the Materials Science suited for use in the fins of heat exchangers. into the microstructure of Cu proBraze heat exchanger. For those interested in a deeper explana- The combination of strength and thermal materials will be delighted by the recent Details can be found in SAE Paper research results on the interactions Number 2001-01-1726. tion of the metallurgy of Cu proBraze conductivity allows the construction of alloys, a new SAE paper by Falkenö and lightweight radiators for use in automo- Ainali serves as a good introduction biles as well as . Professor Olof Forsen´ of Helsinki (SAE Paper Number 01HX-18). Similarly the new brass alloy devel- University of Technology recently This paper describes anneal-resistant oped for tubes also resists softening at published research showing that the corrosion resistance of CuproBraze copper alloys for fins, anneal-resistant brass elevated . The tubing alloy radiators is very competitive with alloys for tubes and brazing materials for consists of 85% copper and 15% zinc that of brazed aluminum radiators. joining fins and tubes. plus about 1 percent iron, which forms It describes why chromium is used as an particles about 200 nanometers in size. alloying element in copper fins. In summary, The latter particles prevent re-crystallization coherent precipitates induced during of grains even at elevated temperature. rolling deformation serve as nuclei for the The high copper content contributes to growth of larger precipitates during subse- improved resistance against stress corrosion quent . These precipitates, which cracking and dezincification. The new are about three nanometers in size, effectively SAE paper presents charts that compare prevent softening at temperatures as high the strength of this anneal resistant brass as 650 ºC. In comparison, conventional alloy with conventional alloys. copper alloys for radiators can only withstand Finally, this paper describes copper-nickel- soldering processes of 450 ºC (842 ºF). tin-phosphorus brazing materials, which Electrical conductivity is restored to melt at 600 ºC. This filler material is typically 92 percent of the unalloyed value when converted to a powder, which is mixed