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Title: Cordierite Glass-Ceramics for Dielectric Materials

Abstract

The objective of this project is to examine the potential of using Malaysian silica sand deposit as SiO2 raw material in producing cordierite glass-ceramics (2MgO-2Al2O3-5SiO2) for dielectric materials. Upgraded silica sands from Terengganu and ex-mining land in Perak were used in the test-works. The glass batch of the present work has a composition of 45.00% SiO2, 24.00% Al2O3, 15.00% MgO and 8.50% TiO2 as nucleation agent. From the differential thermal analysis results, the crystallization temperature was found to start around 900 deg. C. The glass samples were heat-treated at 900 deg. C and 1000 deg. C. The X-ray diffraction analysis (XRD) results showed glass-ceramics from Terengganu samples containing mainly cordierite and minor {beta}-quartz crystals. However, glass-ceramics from ex-mining land samples contained mainly {alpha}-quartz and minor cordierite crystals. Glass-ceramics with different crystal phases exhibit different mechanical, dielectric and thermal properties. Based on the test works, both silica sand deposits, can be potentially used to produce dielectric material component.

Authors:
; ;  [1]
  1. Minerals Research Centre, Department of Minerals and Geoscience Malaysia, Jalan Sultan Azlan Shah, 31400 Ipoh (Malaysia)
Publication Date:
OSTI Identifier:
21061696
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 909; Journal Issue: 1; Conference: ICSSST 2006: 2. international conference on solid state science and technology 2006, Kuala Terengganu (Malaysia), 4-6 Sep 2006; Other Information: DOI: 10.1063/1.2739837; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; CERAMICS; CRYSTAL STRUCTURE; CRYSTALLIZATION; CRYSTALS; DIELECTRIC PROPERTIES; DIFFERENTIAL THERMAL ANALYSIS; GLASS; HEAT TREATMENTS; MAGNESIUM OXIDES; NUCLEATION; QUARTZ; SILICA; THERMODYNAMIC PROPERTIES; TITANIUM OXIDES; X-RAY DIFFRACTION

Citation Formats

Siti Mazatul Azwa Saiyed Mohd Nurddin, Selamat, Malek, and Ismail, Abdullah. Cordierite Glass-Ceramics for Dielectric Materials. United States: N. p., 2007. Web. doi:10.1063/1.2739837.
Siti Mazatul Azwa Saiyed Mohd Nurddin, Selamat, Malek, & Ismail, Abdullah. Cordierite Glass-Ceramics for Dielectric Materials. United States. doi:10.1063/1.2739837.
Siti Mazatul Azwa Saiyed Mohd Nurddin, Selamat, Malek, and Ismail, Abdullah. Wed . "Cordierite Glass-Ceramics for Dielectric Materials". United States. doi:10.1063/1.2739837.
@article{osti_21061696,
title = {Cordierite Glass-Ceramics for Dielectric Materials},
author = {Siti Mazatul Azwa Saiyed Mohd Nurddin and Selamat, Malek and Ismail, Abdullah},
abstractNote = {The objective of this project is to examine the potential of using Malaysian silica sand deposit as SiO2 raw material in producing cordierite glass-ceramics (2MgO-2Al2O3-5SiO2) for dielectric materials. Upgraded silica sands from Terengganu and ex-mining land in Perak were used in the test-works. The glass batch of the present work has a composition of 45.00% SiO2, 24.00% Al2O3, 15.00% MgO and 8.50% TiO2 as nucleation agent. From the differential thermal analysis results, the crystallization temperature was found to start around 900 deg. C. The glass samples were heat-treated at 900 deg. C and 1000 deg. C. The X-ray diffraction analysis (XRD) results showed glass-ceramics from Terengganu samples containing mainly cordierite and minor {beta}-quartz crystals. However, glass-ceramics from ex-mining land samples contained mainly {alpha}-quartz and minor cordierite crystals. Glass-ceramics with different crystal phases exhibit different mechanical, dielectric and thermal properties. Based on the test works, both silica sand deposits, can be potentially used to produce dielectric material component.},
doi = {10.1063/1.2739837},
journal = {AIP Conference Proceedings},
number = 1,
volume = 909,
place = {United States},
year = {Wed May 09 00:00:00 EDT 2007},
month = {Wed May 09 00:00:00 EDT 2007}
}
  • The development of monodisperse crystalline particles in cordierite glass doped with Cr3+ after a two-step heat treatment is elucidated by a combination of time-resolved small and wide angle x-ray scattering (SAXS/WAXS) experiments with electron microscopy. The effects of bulk and surface crystallization can clearly be distinguished, and the crystallization kinetics of the bulk phase is characterized. The internal pressure due to structural differences between the crystalline and amorphous phase is measured but the physical cause of this pressure can not unambiguously be attributed. The combined measurements comprise a nearly full characterization of the crystallization processes and the resulting sample morphology.
  • A study was conducted of the subcritical crack growth in a series of cordierite glass-ceramics, including the original glass, by means of the double-torsion method and measurement of the strain-rate sensitivity of the strength of specimens with controlled indentation cracks subjected to biaxial flexure. The double-torsion data showed that the same rate of crack growth required a stress intensity factor for the fully crystallized glassceramic about 3 times higher than for the original glass, accompanied by a simultaneous increase in the stress intensity exponent (N). The suppression in the rate of crack growth in the crystallized material at any valuemore » of stress intensity factor was attributed to enhanced crack deflection around the crystallites. Limited observations suggested that the increase in N on crystallite formation may be due to a greater degree of crack deflection at the lower crack velocities than at the higher velocities. For strength specimens of the as-received and crystallized glass with large surface flaws, the N values obtained by the strain-rate measurements and the doubletorsion test showed good agreement. However, for the fully crystallized material with surface flaws too small to interact significantly with the coarser crystallites, the N value for the strain-rate data was well below the value for the double-torsion method. Indentation-fracture data of the double-torsion specimens confirmed the existence of crack-size dependent fracture toughness. Limited fracture toughness data coupled with SEM fractography indicated that with increasing crystallite size toughening occurs by crack deflection as well as by microcrack toughening counteracted by fracture through the crystallites.« less
  • Crystallization of an MgO-Al/sub 2/O/sub 3/-SiO/sub 2/-ZrO/sub 2/ sintered glass frit was studied. Heat treatment at 850/sup 0/ or 900/sup 0/C caused initial crystallization of ..mu..-cordierite and tetragonal (t) ZrO/sub 2/. The t-ZrO/sub 2/ crystallized with an irregular dendritic morphology and could be transformed to monoclinic (m) symmetry under certain conditions; the cordierite underwent the ..mu.. ..-->.. ..cap alpha.. transformation with extended annealing. Heat treatments at 1000/sup 0/C caused crystallization of t-ZrO/sub 2/ rods and spheroids in a cordierite matrix; these ZrO/sub 2/ crystals, however, are resistant to transformation to m-ZrO/sub 2/. The beneficial effects of ZrO/sub 2/ on themore » fracture toughness of cordierite-based glass-ceramic are described.« less
  • Cordierite-based ceramics were developed by sintering a glass selected from MgO-Al{sub 2}O{sub 3}-SiO{sub 2} system with an aim to use the material as high frequency chip inductors. A small amount of B{sub 2}O{sub 3} and P{sub 2}O{sub 5} were added to optimize the preparation conditions. The glass powder and sintered bodies were characterized by different analytical techniques such as TG-DTA analysis, X-ray diffraction, transmission and scanning electron microscopy. Pellets uniaxially pressed from the glass power could be sintered well at 950 deg. C having a density of above 99% theoretically, dielectric constant of 5.5, dielectric loss of 0.001 and thermalmore » expansion coefficient of 26.7x10{sup -7} deg. C{sup -1} (20-400 deg. C). Crystalline phases in this sintered sample are predominantly {alpha}-cordierite (hexagonal high cordierite) and trace amount of {mu}-cordierite. SEM depicted a uniformly dense microstructure with crystals of granular habit in the sintered sample.« less
  • This paper reports an experimental study of the dielectric properties of lithium aluminosilicate photosensitive glass ceramics with the following chemical composition: SiO/sub 2/, Li/sub 2/O, K/sub 2/, Na/sub 2/O, Al/sub 2/O/sub 3/, AgNo/sub 3/, CeO/sub 2/. The specimens studied were prepared in the form of flat disks 50 mm in diameter 2 mm thick and were subjected to various thermal and irradiation treatments. Phase analysis determined that the original light-sensitive glass and the glass treated at 520 C contained only an amorphous phase.