A preferred intermetallic diffusion barrier for use in the inventive method is {HEAD ~ noble metal eggshell catalyst} comprising {TAIL ~ zirconia} stabilized with yttria, in particular zirconia stabilized with 6 to 8 wt % yttria 
comprising
A preferred intermetallic diffusion barrier for use in the inventive method is { HEAD ~ noble metal eggshell catalyst } comprising { TAIL ~ zirconia } stabilized with yttria , in particular zirconia stabilized with 6 to 8 wt % yttria
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH