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Characterization of High‐Fracture Toughness K‐Fluorrichterite‐Fluorapatite Glass Ceramics
Author(s) -
Mirsaneh Mehdi,
Reaney Ian M.,
Hatton Paul V.,
James Peter F.
Publication year - 2004
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1551-2916.2004.00240.x
Subject(s) - materials science , fluorapatite , microstructure , fracture toughness , composite material , flexural strength , wollastonite , diopside , mineralogy , phase (matter) , scanning electron microscope , apatite , chemistry , raw material , organic chemistry
Stoichiometric K‐fluorrichterite (Glass A) and the same composition with 2 mol% P 2 O 5 added (Glass B) were prepared and then heat‐treated isothermally from 550°–1000°C with 50°C intervals. Samples were characterized using X‐ray diffraction (XRD) and transmission electron microscopy (TEM). The biaxial flexural strength and indentation fracture toughness of heat‐treated glass specimens were also determined for both materials. XRD traces and TEM images showed similar phase evolution and fine microstructures for both systems at ≤950°C, with mica and diopside reacting with residual glass to form K‐fluorrichterite as the temperature was increased from 650°C. However, in Glass B, fluorapatite was also present at >800°C. In contrast, coarser microstructures were observed at 1000°C, with larger K‐fluorrichterite (20 μm) and enstatite (10 μm) crystals in Glasses A and B, respectively. The highest fracture toughness (2.69 ± 0.01 MPa·m 1/2 ) and biaxial strength (242.6 ± 3.6 MPa) were recorded for Glass B heat‐treated at 1000°C. This was attributed to the presence of enstatite coupled with an interlocked lath‐like crystalline microstructure.