Superalloy Skin on Nickel Open-Pore Foam Deposited by Thermal Spray Processes

Abstract: Open pore MetIIlIic foaMS eIIn be IIsedfor high teMperature, high perforMance hatexchanger dlle to their high gas pemrMbility and hat conductivity provided that skins properly attach to thefoaM's strllts on the sllrface. In the CII"ent study, a IIOvel process was successfully developed to fiIJ pores on the sllrface ofthe foaM sheet in order to deposit skin on the foaM lpf!dInens by therMal spraying. Nickel basedsllpe1YlUoy (lnconel 625) skins were deposited on ach side ofa sheet ofnickel MeIIII /HIlI with different pore densities of10 and 20 pores per inch by high velocity oxy-fllel (HVOF), tltMospheric plaSMa spraying (APS), and twin wire arc spraying to forM a sandwich structllre. The sandwich strllctllre eIIn be IISed in high temperature hat txduutger applicatillns. TIle penetratilln ofthe coating MII.teriIIIs into thefDilM strllts can be controUed throllgh thefilling process Nfore spraying. The Microslrllctllre ofthe skins and the adhesion III the interface between the nickelfOtlM's struts andskins were ~Resllits showed dense skins with good adhesuln to the slIrfaces ofthefoa".. The fDllln 's strllts were iMbedded into tU CfNIIbIgs deposited by HVOF More deeply than the cDiltings deposited by APS and wire arc spraying. Skins deposited by IWOF and wire arc spraying showed higher bending strength 'han the skin deposited by APS dlle to lower porosity and oxide mttent in the coating.