火烧环境中铜缆线燃烧痕迹宏微观特征

Macro and Micro Characteristics of Burning Traces of Copper Cable in Fire Environment

为探究涉铜缆线电气火灾的起火原因,通过设计并开展燃烧实验制备铜缆线燃烧试样,综合采用体视显微镜、扫描电镜对试样燃烧痕迹的宏、微观形态特征进行观察分析,讨论线缆规格尺寸、有无绝缘层以及不同燃烧温度对燃烧痕迹宏观形态和微观组织特征的影响。研究结果表明:对于相同规格的铜缆线,绝缘层材料的存在提高了缆线燃烧温度的极值,但二者的熔断温度相差不大,同时,也降低了缆线燃烧后熔端的集束性;随着缆线截面尺寸的增加,其燃烧过程中达到的温度极值也不断提高,不同规格铜缆线的熔断温度总体上与其截面尺寸成正比;铜缆线在高温作用下易形成熔珠,其直径通常为铜线线径的1~3倍,裸铜缆线形成的熔珠表面较光滑,具有金属光泽,而含绝缘层铜缆线形成的熔珠表面较粗糙,附着聚氯乙烯残留物。研究结果可为铜缆线在火场环境中燃烧痕迹的分析及起火原因的判别提供依据。

In order to explore the cause of the electrical fire involving copper cables,the burning samples of copper cables were prepared by combustion experiment.Stereo microscope and scanning electron microscope were used to observe the macroscopic and microscopic morphological characteristics of the burning traces.The influences of cable’s size,insulating layer and burning temperature on macro-morphology and micro-structural characteristics of burning traces were discussed.The results show that the existence of the PVC insulation layer increases the extreme value of the cable’s burning temperature,but has little effect on the fusing temperature,meanwhile,the existence of the insulation layer also reduces the clustering of the fused end of the cable after burning.With the increase of the cable size,the temperature extreme value also continues to increase during the combustion process,and the fusing temperature of copper cables is generally proportional to their cross-sectional size.The copper cable is easy to form molten beads under the action of high temperature,and its diameter is usually 1~3 times of the diameter of the copper wire.The surface of the bead formed by the bare copper cable is smoother and has metallic luster,while the surface of the bead formed by the copper cable with the insulation layer is rougher and adheres to the PVC residue.This research can provide a basis for the analysis of the burning traces of copper cables in the fire environment and the identification of the cause of the fire.