Electron microscopy of water trees in XLPE

摘要

The infiltration/permanganic etching technique employed, allows water trees to be examined using a variety of optical and electron imaging techniques. In addition to the gross structure of the tree, examination of the water treed regions by TEM enables both the tree itself and the surrounding matrix morphology to be examined simultaneously and in unprecedented detail. The technique has revealed a wide variety of tree structures, ranging from trees composed of a small number of coarse radiating units, through a congested array of channels, to structures where the envelope of the tree appeared to be filled with small voids. Thus, it is proposed that whilst some water trees are made up of radiating channels, others may contain discrete voids. Only in one material was it possible to detect voiding beyond the envelope of the tree.