SEM Analysis on Burning Melted Beads of Copper Wire

In this study, melted marks of different cross section copper wires were prepared by simulating the conditions of the fire scene. The influence of the temperature and time in fire environment, the cooling rate, and the cross section of the wires on the microstructures of the burning melted beads was studied by scanning electron microscope (SEM) systematically. The prepared melted marks were put into the muffle furnace for different thermal treatments, and then cooled by air or spraying water. With increasing the temperature and prolonging the heating duration, the crystal boundary became more compact and the crystal particles distributed more regularly. Particularly, when the burning melted beads formed at a high temperature of about 1200°C and cooled by spraying water, the typical eutectoid organizations were observed which are commonly formed in the primary short circuited melted beads. And the beads prepared with the thinner wire are more sensitive to the change of the environment. The study is provided as references for fire traces evidence identification of electrical fire.