News | Published:

INSULATOR GLAZES

    Naturevolume 150pages771772 (1942) | Download Citation

    Subjects

    Abstract

    AN article by E. Rosenthal in the Electrical Review of November 27 discusses the influence of insulator glazes on porcelain, having particular reference to high-voltage insulators. Under a strong microscope the surfaces of unglazed ceramic materials show minute projecting peaks which make it evident that the quality of the surface has a great bearing on the surface resistivity. This, in turn, is largely dependent on the humidity skin which, in a moist atmosphere, forms on any surface to a thickness that increases with the surface roughness and with atmospheric humidity. With 30 per cent humidity, the surface resistance of unglazed porcelain ranges between 20 and 40 X 1012 ohms / sq. cm., but with 98 percent humidity it is only about 0.001 x 1012. This decrease in surface resistivity is smaller the smoother the surface. In a dry atmosphere glazed porcelain has approximately the same surface resistance as unglazed porcelain, but in a humid atmosphere of, for example, 98 per cent humidity the figure becomes 0-1 x 1012 ohms/sq. cm. This dependence of surface resistivity on the quality of the surface and on the humidity content of the atmosphere is a characteristic not only of porcelain but also of all insulating materials.

    About this article

    Publication history

    Issue Date

    DOI

    https://doi.org/10.1038/150771b0

    Comments

    By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.

    Newsletter Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing