In this paper, AgNO3 (silver nitrate) solution was used as liquid electrode to accelerate the growth of water trees in polyethylene. It was found that water trees grown in AgNO3 solution can be colored spontaneously during their formation, their areas are brownish-yellow, and they grow fast. Scanning electron microscopy (SEM) revealed microchannels in the AgNO3-grown water tree with diameters from 0.2 to 0.5 mu m. In fact,these microchannels are possibly filled with metallic silver reduced from silver ions, and these water trees are referred to as 'silver trees'. The structure of the silver trees is studied and analyzed in comparison with sulfide trees and blue water trees. The effects of silver ions (Ag+) in the silver tree region are investigated and a comparison is made with other ions such as KS, Na+, Mg++, and Cu++ in water trees. The trees from AgNO3 solution grow much faster than trees from the other solutions. Finally, the mechanism of the formation of silver trees is suggested.
