The mineralogy and firing behaviour of pottery clays of the Lake Van region, eastern Turkey

AbstractThe present study focused on the mineralogical and chemical characterization and firing behaviour of clays from the Lake Van region and compared them with the same characteristics established for two ancient pot sherds. Four pottery clays collected from Kutki and Kuşluk in the Kesan Valley to the south, from Kavakbaşı to the southwest and from Bardakçı village on the east coast of Lake Van were analysed by X-ray diffraction to identify mineralogical composition (bulk clays and <2 μm fractions after heating at 300–500°C and ethylene glycol solvation). Further analyses were conducted to determine the size distribution, chemical composition and physical properties of test bodies derived from these clays. The in situ weathered schist forming the primary micaceous red clays which are suitable for local pottery production are characterized by large muscovite-sericite-illite and small calcite contents. In contrast, the Bardakçı clays are dominated by large smectite contents and are only used sparingly in mixtures of local pottery production because they undergo firing shrinkage and present drying and firing flaws in the fired bodies. Firing ranges of ~800–900°C were inferred from the mineralogy and colours of the two ancient sherds from Kutki. As a result of mineralogical analysis of fired and unfired test bodies of these pottery clays and pot sherds, two different types of pastes were determined for pottery production in the Lake Van region: metamorphic and volcanic paste, the former characterized by a calcite-poor and mica-sericite-rich matrix and the latter by large smectite and small calcite contents.

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Using Lime Mud Waste from Pulp Mill as an Additive in Brick Clay

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.608.3 ◽

2014 ◽

Vol 608 ◽

pp. 3-7

Author(s):

Srichalai Khunton ◽

Siriphan Nilpairach ◽

Supin Sangsuk

Keyword(s):

Particle Size ◽

Particle Size Distribution ◽

Size Distribution ◽

Pulp Mill ◽

Mineralogical Composition ◽

X Ray Diffraction ◽

Brick Clay ◽

X Ray ◽

Lime Mud ◽

Firing Shrinkage

Lime mud from a pulp mill was used as an additive in brick clay from the southern part of Thailand. It was mixed with the clay from Cha-Aud district, Nakorn Sithammarat province. The chemical composition of lime mud and the clay was characterised by X-ray fluorescence (XRF), and the mineralogical composition was measured by X-ray diffraction (XRD). The particle size distribution was also measured. The main composition of lime mud is CaO, and Cha-Aud clay consists of SiO2 and Al2O3 as major oxides. The lime mud contains calcite as a major phase when Cha-Aud clay is constituted by quartz, kaolinite, illite and goethite. Particle size distribution of lime mud is in the range of 1-50 μm. After the lime mud was neutralized using hydrochloric acid, it was mixed with Cha-Aud clay at 10 wt%. Samples with and without lime mud were sintered at 700, 800, 900 and 1000°C for 1 hour. The results showed that lime mud can be used as an additive in brick clay. Both types of samples were similar in terms of physical properties when their linear firing shrinkage, water absorption and flexural strength were in the same range.

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Carboxylic acids: effective inhibitors for calcium sulfate precipitation?

Mineralogical Magazine ◽

10.1180/minmag.2014.078.6.13 ◽

2014 ◽

Vol 78 (6) ◽

pp. 1465-1472 ◽

Cited By ~ 28

Author(s):

Taher Rabizadeh ◽

Caroline L. Peacock ◽

Liane G. Benning

Keyword(s):

Electron Microscopy ◽

Carboxylic Acids ◽

Calcium Sulfate ◽

Mineralogical Composition ◽

The Other ◽

X Ray Diffraction ◽

X Ray ◽

Scanning Electron ◽

Better Than

Results are reported here of an investigation into the effects of three carboxylic acid additives (tartaric, maleic and citric acids) on the precipitation of calcium sulfate phases. Precipitation reactions were followed at pH 7 in the pure CaSO4 system and in experiments with 0–20 ppm carboxylic acids added using in situ UV-VIS spectrophotometry (turbidity). The solid products were characterized in terms of their mineralogical composition, using X-ray diffraction, during and at the end of each reaction, and in terms of their morphological features, by scanning electron microscopy. All additives increased the time needed for turbidity to develop (induction time, start of precipitation) and the comparison between additive and additive-free experiments showed that, at equivalent concentrations, citric acid performed far better than the other two carboxylic acids. In all cases bassanite precipitated first and with time it transformed to gypsum. The addition of citrate stabilized bassanite and changed the final gypsum habit from typical needle-like crystals in the pure CaSO4 system to plates in the citrate-additive experiments.

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Pulsed electric current sintering of TiB2-based ceramics using nitride additives

Synthesis and Sintering ◽

10.53063/synsint.2021.1112 ◽

2021 ◽

Vol 1 (1) ◽

pp. 28-33

Author(s):

Naeimeh Sadat Peighambardoust ◽

Çağın Çevik ◽

Tannaz Assar ◽

Sunghoon Jung ◽

Seon Yong Lee ◽

...

Keyword(s):

Ex Situ ◽

X Ray Diffraction ◽

Si3n4 Ceramic ◽

X Ray ◽

Pulsed Electric Current ◽

Different Types ◽

Microstructural Evaluation ◽

In Situ Formation ◽

Field Assisted Sintering

In this research, various types of nitride additives were incorporated into titanium diboride attaining dense TiB2-based ceramics by field-assisted sintering technique. The addition of different types of nitride additives, namely Si3N4, BN, AlN, and TiN, significantly improved the sinterability of TiB2, achieving near fully dense ceramics. The X-ray diffraction analysis and microstructural evaluation confirmed the presence of the h-BN compound in all specimens. In the TiB2-Si3N4 ceramic, Si3N4 additive reacted with B2O3 oxide, in-situ generating h-BN, and SiO2 phases. Although the h-BN phase was produced in the TiB2-AlN specimen, the main proportion of AlN remained in the sample as an unreacted ex-situ phase. In terms of the TiB2-TiN ceramic, some of the nitrogen and boron atoms could leave the TiN and TiB2 crystalline structures, contributing to the in-situ formation of h-BN.

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The Use of Advanced Analytical Techniques for Characterization of the Chemical, Physical, and Crystallographic Nature of a Surface

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100071107 ◽

1973 ◽

Vol 31 ◽

pp. 132-133 ◽

Cited By ~ 1

Author(s):

R. E. Herfert

Keyword(s):

Surface Characterization ◽

Analytical Techniques ◽

X Ray Diffraction ◽

Depth Of Penetration ◽

X Ray ◽

The Past ◽

Transmission Electron ◽

Scanning Electron

Studies of the nature of a surface, either metallic or nonmetallic, in the past, have been limited to the instrumentation available for these measurements. In the past, optical microscopy, replica transmission electron microscopy, electron or X-ray diffraction and optical or X-ray spectroscopy have provided the means of surface characterization. Actually, some of these techniques are not purely surface; the depth of penetration may be a few thousands of an inch. Within the last five years, instrumentation has been made available which now makes it practical for use to study the outer few 100A of layers and characterize it completely from a chemical, physical, and crystallographic standpoint. The scanning electron microscope (SEM) provides a means of viewing the surface of a material in situ to magnifications as high as 250,000X.

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