Sintered sub-micron Al2O3 is the hardest of all transparent materials for compact windows, and a high hardness is important for the ballistic performance. However, visible light transmission of sintered alumina is limited by birefringent scattering to a real in-line transmission RIT of only 70-75 % of the theoretical maximum (at 0.8-1 mm thickness). These losses increase with thickness whereas a safe ballistic performance requires 1.5-2 mm at least. Slip casting brings ''real'' in-line transmission (RIT) closer to the limit with grain sizes of 0.3 micron (at 0.8 mm thickness: 84-93 % of the theoretical maximum) but these results give again rise to doubt that it will ever be possible to manufacture larger and thicker Al2O3 windows with a sufficiently high transparency. On the other hand, new fine-grained spinel associates an RIT close to the theoretical maximum with a hardness that approaches sapphire. In first ballistic tests this spinel outperformed sapphire. It is, therefore, suggested that sub-micron Al2O3 may be good for IR windows or as armour for low threat applications (where thinner tiles can be used). For thicker windows, however, the new spinel appears as a most favourable candidate.


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    Title :

    Transparent armour ceramics: Spinel vs sub-micron Al2O3


    Additional title:

    Transparente schusssichere Keramik: Gegenüberstellung von Spinell mit Submikron-Al2O3


    Contributors:
    Krell, A. (author) / Hutzler, T. (author) / Klimke, J. (author)


    Publication date :

    2008


    Size :

    6 Seiten, 8 Bilder, 1 Tabelle, 18 Quellen



    Type of media :

    Conference paper


    Type of material :

    Storage medium


    Language :

    English




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