Microstructural Study on Molten Marks of Fire-Causing Copper Wires

Materials

Kuan-Heng Liu²  Yung-Hui Shih²  Guo-Ju Chen¹  Jaw-Min Chou¹ 

[1] Department of Materials Science and Engineering, I-Shou University; No.1, Sec. 1, Syuecheng Rd., Dashu Dist., Kaohsiung City 84001, Taiwan;

关键词: copper;    dendrite growth;    solidification microstructure;    transmission electron microscopy;    fire;    fire investigation;    fire scene;    electrical short circuit;    electrical arc beads;   

DOI  :  10.3390/ma8063776

来源: mdpi

【 摘 要 】

Although electrical fires constitute the greatest percentage of the main causes of building fires, the critical evidence used by fire investigators to identify electrical fires is not always convincing to the general public. In this study, we scrutinized the microstructures of fire-causing copper wires and simulated the external environmental conditions required for the formation of fire-causing arc beads. Our metallographic investigation revealed that the primary thermal dendrites of copper at the fire-causing arc bead grew parallel to one another, but in the opposite direction to the heat flow. We determined the relationships of the undercooling (∆T₀), the growth velocity (ν), and the primary spacing (λ) of the dendrites with respect to the electrical wire’s diameter. Accordingly, fire investigators can now identify fire-causing arc beads in terms of these metallographic characteristics, thereby providing clear scientific evidence for litigant judgments of electrical fires.

【 授权许可】

CC BY   
© 2015 by the authors; licensee MDPI, Basel, Switzerland.