不同使用状况下热得快电热丝的显微断口形貌分析

Fracture Surface Morphologies Analysis on Heating Wire of Immersion Heaters under Different Service Conditions

为了鉴别热得快在火灾发生之前是否处于干烧过热状态,模拟未使用、正常使用、干烧过热以及上述三种情形后再受火灾作用时的试验条件,获得不同使用情况下的热得快电热丝样品,采用相同的应变速率将获得的电热丝拉断并使用扫描电子显微镜观察其显微断口形貌。结果表明:相同使用状态的热得快电热丝受外热前后显微断口形貌特征变化不大,即一般火场温度对电热丝显微断口形貌的影响较小;不同使用状态下的热得快电热丝显微断口形貌特征差异明显。通过电子扫描显微镜对热得快电热丝显微断口形貌分析,可以为鉴别热得快在火灾发生前的通电状态提供一种新的方法和依据。

In order to identify whether the immersion heaters were electrically overheated or not the simulation of a conflagration by a high - temperature furnace on the not used, normally immersion heaters were investigated, and fracture surface morphologies of the before and after before the conflagra-used and overheated burned heating wires were observed by scanning electron microscope （SEM）. The result indicates that the heating wire are less affected by the conflagration as the little difference exhibited between the before and after burned sample, but fracture sur-faces of heating wires under different service conditions have obvious differences and have a certain variation. There-fore, the analysis on fracture surface morphologies by SEM can be used to reveal the work status of the immersion heaters before the conflagration.