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Design, fabricability, thermal, mechanical, physical and durability properties are all important to the successful application of materials systems to heat exchangers. In recent years, use of clad metals for furnace brazing of heat exchangers has increased significantly. These brazing materials have proven to be cost effective and reliable and the properties of the materials can be tailored to the heat exchanging application. The primary materials used in these applications range from copper clad steel to copper clad stainless steel. Selection of the component metals determines the properties of the materials system and therefore provides the properties desired in the heat exchanger. This paper discusses the process used to fabricate copper clad self brazing material and for brazing heat exchangers. Factors important in the selection of a particular materials systems are described and data is provided on the properties of these materials in heat exchangers.

Vehicle heat exchangers are exposed to a number of aqueous environments ranging from inhibited coolants to seawater. Frequently, the design of the heat exchanger results in a galvanic couple between copper and a stainless steel. This couple can either prevent or promote pitting and crevice corrosion of the stainless steel member. This paper demonstrates the use of electrochemical corrosion measurement techniques to predict this behavior. Stainless steels which have acceptable, marginal and unacceptable resistance to localized corrosion when coupled to copper in aggressive environments are described. Potentiodynamic polarization curves for a variety of stainless steels were measured in artificial seawater to determine their pitting and critical protection potentials. Mixed potential measurements for these alloys galvanically coupled to copper were then made to predict the localized corrosion behavior of the stainless steel.