STRESS SYSTEMS IN THE SOLDEKLESS AVKAIM'ED COX X EC'l'lOX 1101) 



10* 10^ 10^ lO' 



TIME IN SECONDS 



Fig. 15 — Stripping force and shear strength of coppcr-zinc-brass connections 

 as a function of time and temperature. 



be made to approach the cold welding condition. This requires that 

 aluminum be placed on a stronger material such as brass, nickel silver 

 or copper in order that the area of indentation for a given hoop stress 

 will decrease and the shear stress will increase. Hence, the connection 

 should form in a very short time. Furthermore, since the limiting shear 

 stress for aluminum is near 0,000 pounds per square inch, one should 

 except that the strength of the connection will nearly double. Since 

 aluminum is not easih^ electroplated this suggestion probably is not 

 practical. 



Of all the other metals examined, the next most promising are silver, 

 cadmium and zinc. The activation energy for diffusion of zinc into copper 



01 2345678 



HOOP STRESS IN THOUSANDS OF POUNDS PER SQUARE INCH 



Fig. 16 • — • Activation energy for a copper-ziric-hra.ss connection u.s a function 

 of hoop stress. 



