Transparent MgAl2O4/LiF ceramics by hot-pressing: Host–additive interaction mechanisms issue revisited

Hot-pressing schedules – able to ensure a proper balance between positive and negative effects of LiF – allow fabrication of highly transparent MgAl2O4 parts under low-pressure (≤50MPa); peak temperatures in excess of 1550°C are needed, with best results obtained at ∼1650°C. At the concentration-lev...

Full description

Saved in:
Bibliographic Details
Published in:Journal of the European Ceramic Society 2016-06, Vol.36 (7), p.1731-1742
Main Authors: Goldstein, Adrian, Raethel, Jan, Katz, Michael, Berlin, Mila, Galun, Ehud
Format: Article
Language:English
Subjects:
Armor
Hot-pressing
Optical properties
Sintering
Spinel
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Hot-pressing schedules – able to ensure a proper balance between positive and negative effects of LiF – allow fabrication of highly transparent MgAl2O4 parts under low-pressure (≤50MPa); peak temperatures in excess of 1550°C are needed, with best results obtained at ∼1650°C. At the concentration-levels and conditions present during hot-pressing, LiF does not react with spinel; it is inert also toward graphite. The lubricant and solvent abilities of liquid LiF make possible achievement of densification levels >90%TD under 1200°C. All LiF leaves the specimens as such at temperatures ≤1550°C. LiF's ability to close porosity at temperatures lower than those (>1350°C) – which allow significant carbon penetration into spinel – is essential in achievement of transparency. Light absorption – occurring when carbon is present – is thus prevented. The main light-scattering defect produced by HPing, in the presence of LiF, is micro and macro-cracking; opaque spots, due to un-complete densification, are rare.
ISSN:0955-2219
1873-619X
DOI:10.1016/j.jeurceramsoc.2016.02.001