Novel Electric Joint Compound With Three-dimensional Fractal Silver Dendrite as Conductive Filler

Abstract

Electric joint compound has been widely used at the connection of power equipment to reduce contact resistance. In order to improve the electrical performance of power compound grease, we need to improve the morphology and distribution of conductive fillers. In this paper, three-dimensional nano-silver dendrites are used as conductive fillers in the electric joint compound for the first time. Three-dimensional fractal silver dendrite was prepared by solution phase reduction method at room temperature and added to base oil as conductive filler to prepare a new type of electric composite grease. The effect of feeding speed on morphology and structure of silver dendrite was analyzed by changing feeding speed. The effects of temperature on the conductivity of electric composite grease were studied. Different structures of silver particles were also compared. The different function of one-dimensional silver wire, two-dimensional silver sheet and three-dimensional fractal silver dendrite are explained. It was concluded that the number of silver dendrite fractal structures formed by solution reduction increased with the increase of feed rate. Under the condition of 15 mL/min feeding rate and 18:1 molar ratio (hydroxylamine: silver nitrate, the molar concentration of silver nitrate is 0.6 mol/L), the three-dimensional structure of silver dendrites is the most abundant. The electrical conductivity of electric composite grease increases almost linearly with the increase of temperature. However, the content of conductive filler has little effect on the increase of conductivity. Three-dimensional fractal silver dendrite performs much better than one-dimensional silver wire and two-dimensional silver sheet. The electric composite grease using three-dimensional silver dendrite as conductive particles has higher conductivity. Because the surface morphology of three-dimensional fractal silver dendrite is more abundant and the spatial structure of three-dimensional fractal silver dendrite is more complex. Which means it is easier for three-dimensional fractal silver dendrite to form percolation network between particles.