TY - JOUR
T1 - Microstructure and mechanical properties of synthetic opal
T2 - A chemically bonded ceramic
AU - Simonton, Thomas C.
AU - Roy, Rustum
AU - Komarneni, Sridhar
AU - Breval, Else
AU - Komarneni, Sridhar
N1 - Funding Information:
The senior author gratefully acknowledges extensive discussions with Dr. B. E. Scheetz, Dr. D. K. Smith, and M. Silsbee. This research was supported by the Chemical and Atmospheric Sciences Program, U. S. Air Force Office of Scientific Research, under Contract No. F49620-85-C-0069.
PY - 1986/10
Y1 - 1986/10
N2 - Among chemically bonded ceramics (i.e., those not utilizing thermally activated diffusion for bonding) the French synthetic opal gilsonite provides an excellent existence theorem. By using optical, scanning, and electron microscopy techniques and x-ray, chemical, and differential thermal analyses, it is shown for the first time that the synthetic opal is composed of two separate phases: noncrystalline silica and crystalline (tetragonal) zirconia balls. The zirconia balls with sizes ranging from 7–50 nm appear to be present in an extraordinary regular “lattice” in the void spaces of the silica “balls” of mean size 200 nm. A comparison of the fracture toughness, KIC, data for the gilsonite and natural opal shows that the former is significantly tougher than the latter. The KICvalues for gilsonite fall between those of the Corning 0337 Glass Ceramic and Wesgo Al-500 alumina, showing that surprisingly tough ceramics can be made near room temperature by resorting to chemical bonding.
AB - Among chemically bonded ceramics (i.e., those not utilizing thermally activated diffusion for bonding) the French synthetic opal gilsonite provides an excellent existence theorem. By using optical, scanning, and electron microscopy techniques and x-ray, chemical, and differential thermal analyses, it is shown for the first time that the synthetic opal is composed of two separate phases: noncrystalline silica and crystalline (tetragonal) zirconia balls. The zirconia balls with sizes ranging from 7–50 nm appear to be present in an extraordinary regular “lattice” in the void spaces of the silica “balls” of mean size 200 nm. A comparison of the fracture toughness, KIC, data for the gilsonite and natural opal shows that the former is significantly tougher than the latter. The KICvalues for gilsonite fall between those of the Corning 0337 Glass Ceramic and Wesgo Al-500 alumina, showing that surprisingly tough ceramics can be made near room temperature by resorting to chemical bonding.
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U2 - 10.1557/JMR.1986.0667
DO - 10.1557/JMR.1986.0667
M3 - Article
AN - SCOPUS:0022910023
SN - 0884-2914
VL - 1
SP - 667
EP - 674
JO - Journal of Materials Research
JF - Journal of Materials Research
IS - 5
ER -