Doing that will make tip erosion worse, not better. Take a look at Figures 3 and 4 at
http:// www . hakkousa . com / leadfree . asp (remove spaces)
"Comparison of Solder Composition and Erosion Rate
The rate of tip erosion varies with different solder alloy compositions. As shown in Figure 4, Sn-0.7Cu (tin/copper) erodes the tip faster than Sn-3.5Ag-0.75Cu (tin/silver/copper), which erodes faster than Sn-3.5Ag (tin/silver) solder, which erodes faster than Sn-37Pb (tin/lead), etc."
So adding silver to the solder is the wrong thing to do. To learn about what the right thing to do is, please read "Extending Soldering Iron Tip Life" at http://www.newark.com/pdfs/techarticles ... ipLife.pdf
( http:// www . newark . com / pdfs / techarticles / oki-metcal / extendingTipLife . pdf )