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Title: A quantitative-metallographic study of the sintering behaviour of dolomite

Abstract

Grain growth of the MgO phase during sintering of natural dolomite from Selcuklu-Konya in Turkey was studied in the temperature range 1600-1700 deg. C. For comparison purposes, iron oxide (98.66% mill scale) was added up to 1.5%. The compositions of the phases formed during sintering were studied using X-ray diffraction and scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy. Quantitative-metallographic analyses were performed on images taken by SEM. For the automatic image analysis of dolomite microstructures, material (atomic number) contrast with backscattered electrons (BSEs) was utilized because it yields higher phase contrast compared to secondary electrons (SEs). Iron oxide additions to dolomite result in dense dolomite structures at given sintering temperatures, where phases with low melting temperatures are developed. During liquid phase sintering, periclase is enriched with iron, which destabilizes the MgO phase. The relevant kinetic exponents for MgO in the natural doloma and 0.5% Fe{sub 2}O{sub 3} added doloma were 6 and 2, and the activation energies were 108 and 243 kJ/mol, respectively.

Authors:
 [1];  [2];  [3]
  1. Department of Metallurgical and Materials Engineering, Yildiz Technical University, Istanbul (Turkey)
  2. Department of Metallurgical and Materials Engineering, Kocaeli University, Veziroglu Campus, Izmit-Kocaeli 41040 (Turkey)
  3. Department of Metallurgical and Materials Engineering, Kocaeli University, Veziroglu Campus, Izmit-Kocaeli 41040 (Turkey). E-mail: karagoez@kou.edu.tr
Publication Date:
OSTI Identifier:
20748639
Resource Type:
Journal Article
Resource Relation:
Journal Name: Materials Characterization; Journal Volume: 52; Journal Issue: 4-5; Other Information: DOI: 10.1016/j.matchar.2004.06.004; PII: S1044-5803(04)00131-7; Copyright (c) 2004 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ACTIVATION ENERGY; COMPARATIVE EVALUATIONS; DOLOMITE; ELECTRONS; FERRITES; GRAIN GROWTH; IMAGES; IRON; IRON OXIDES; MAGNESIUM OXIDES; MELTING POINTS; METALLOGRAPHY; MICROSTRUCTURE; SCANNING ELECTRON MICROSCOPY; SINTERING; TEMPERATURE RANGE 1000-4000 K; X-RAY DIFFRACTION; X-RAY SPECTROSCOPY

Citation Formats

Yeprem, H.A., Tueredi, E., and Karagoez, S. A quantitative-metallographic study of the sintering behaviour of dolomite. United States: N. p., 2004. Web. doi:10.1016/j.matchar.2004.06.004.
Yeprem, H.A., Tueredi, E., & Karagoez, S. A quantitative-metallographic study of the sintering behaviour of dolomite. United States. doi:10.1016/j.matchar.2004.06.004.
Yeprem, H.A., Tueredi, E., and Karagoez, S. 2004. "A quantitative-metallographic study of the sintering behaviour of dolomite". United States. doi:10.1016/j.matchar.2004.06.004.
@article{osti_20748639,
title = {A quantitative-metallographic study of the sintering behaviour of dolomite},
author = {Yeprem, H.A. and Tueredi, E. and Karagoez, S.},
abstractNote = {Grain growth of the MgO phase during sintering of natural dolomite from Selcuklu-Konya in Turkey was studied in the temperature range 1600-1700 deg. C. For comparison purposes, iron oxide (98.66% mill scale) was added up to 1.5%. The compositions of the phases formed during sintering were studied using X-ray diffraction and scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy. Quantitative-metallographic analyses were performed on images taken by SEM. For the automatic image analysis of dolomite microstructures, material (atomic number) contrast with backscattered electrons (BSEs) was utilized because it yields higher phase contrast compared to secondary electrons (SEs). Iron oxide additions to dolomite result in dense dolomite structures at given sintering temperatures, where phases with low melting temperatures are developed. During liquid phase sintering, periclase is enriched with iron, which destabilizes the MgO phase. The relevant kinetic exponents for MgO in the natural doloma and 0.5% Fe{sub 2}O{sub 3} added doloma were 6 and 2, and the activation energies were 108 and 243 kJ/mol, respectively.},
doi = {10.1016/j.matchar.2004.06.004},
journal = {Materials Characterization},
number = 4-5,
volume = 52,
place = {United States},
year = 2004,
month = 7
}
  • The friction and lateral stiffness of the contact between an atomic force microscopy (AFM) probe tip and an atomically flat dolomite (104) surface were investigated in contact with two aqueous solutions that were in equilibrium and supersaturated with respect to dolomite, respectively. The two aqueous solutions yielded negligible differences in friction at the native dolomite-water interface. However, the growth of a Ca-rich film from the supersaturated solution, revealed by X-ray reflectivity measurements, altered the probe-dolomite contact region sufficiently to observe distinct friction forces on the native dolomite and the film-covered surface regions. Quantitative friction-load relationships demonstrated three physically distinct loadmore » regimes for applied loads up to 200 nN. Similar friction forces were observed on both surfaces below 50 nN load and above 100 nN load. The friction forces on the two surfaces diverged at intermediate loads. Quantitative measurements of dynamic friction forces at low load were consistent with the estimated energy necessary to dehydrate the surface ions, whereas differences in mechanical properties of the Ca-rich film and dolomite surfaces were evidently important above 50 nN load. Attempts to fit the quantitative stiffness-load data using a Hertzian contact mechanical model based on bulk material properties yielded physically unrealistic fitting coefficients, suggesting that the interfacial contact region must be explicitly considered in describing the static and dynamic contact mechanics of this and similar systems.« less