BeschreibungIn this work we investigate commercially available thermoelectric modules (TEM) by infrared (IR) thermography. IR thermography is a non-destructive method which can be applied in practically any processes where temperature is an indicator of abnormal operation of an object. As demonstrated in an earlier work with this method subsurface defects of the multilayered TEM structure can be detected. Additionally advantages of IR thermography are that several TEM’s can be analyzed simultaneously (typically up to 10, depending on their dimensions) and the analyzing time lies in the range of several seconds. TEM’s can be classified in failure free or faulty TEM’s having a ‘weak’ or ‘hard’ failure. Weak failure means, that the TEM is principal operable but the electrical resistance is increased compared to a failure free TEM (e.g. by an increased contact resistance). A hard failure means that the TEM is inoperable because no current can flow (e.g. due to opens). For IR imaging the TEM must thermally excited. In the case of a weak failure, this is done preferred by electrical sourcing (internal joule heating) or alternatively by an external source (e. g. flash lamp or laser). In the case of a hard failure, the TEM must be thermally excited by an external source (e. g. flash lamp or laser). Investigating a TEM with a weak failure, typical parameters of electrical sourcing are a pulsed sine wave with a frequency of 1 Hz, a peak voltage of appr. 5 – 6 V and a peak current of appr. 1 – 2 A. At positions where the failure is located (e. g. by increased electrical resistance) a hot spot occurs. To get information on the physical cause of this failure, a metallographic cross section was carried out and the failure region was inspected by optical microscopy and / or SEM analysis.
|Zeitraum||3 Juli 2018|
|Ereignistitel||37th International and 16th European Conference on Thermoelectrics|