scholarly journals Characterization of some archaeological ceramics and clay samples from Zamala - Far-northern part of Cameroon (West Central Africa)

Cerâmica ◽  
2017 ◽  
Vol 63 (367) ◽  
pp. 413-422 ◽  
Author(s):  
Z. L. Epossi Ntah ◽  
R. Sobott ◽  
B. Fabbri ◽  
K. Bente
Keyword(s):  
Firing Temperature ◽  
Raw Materials ◽  
Central Africa ◽  
Potassium Feldspar ◽  
X Ray Diffraction ◽  
X Ray ◽  
Northern Cameroon ◽  
Homogeneous Chemical ◽  
Chemical Correlation

Abstract Seventeen ceramics samples (515±95 BP, about 580 years old) and two clay raw materials from Zamala (Far-northern, Cameroon) were characterized by X-ray diffraction (XRD), thermal analysis (DTA/TG) and X-ray fluorescence spectroscopy. The aim of the work was the deduction of the production technology and provenance of these ceramics. With the exception of one sample the analysed ceramics formed a homogeneous chemical and mineralogical group. The observed mineralogical phases were quartz, mica (biotite), potassium feldspar (microcline) and plagioclase (albite and oligoclase). The XRD study of two local clays yielded the presence of quartz, kaolinite, mica, feldspar and plagioclase. The presence of the broad endothermic peak in the DTA/TG curves of the clays and its absence in the curves of the ceramics indicated that the firing temperature of the ceramics was above 550-600 °C, which is the temperature of the kaolinite-metakaolinite transformation. The firing experiments of the clay between 400-1200 °C in oxidizing atmosphere showed that mica disappeared above 900 °C. Therefore, the firing temperature of the sherds should have been between 600-900 °C. The chemical correlation between ceramics and local clay materials pointed out to a local production of these ceramics.

Synthesis and Characterization of New Polyurethane Adhesives

2006 ◽  
Vol 514-516 ◽  
pp. 843-847 ◽  
Author(s):  
Cristina Borges Correia ◽  
João C. Bordado
Keyword(s):  
Raw Materials ◽  
Impact Resistance ◽  
Inert Atmosphere ◽  
Stray Field ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Polyurethane Adhesives ◽  
Dimer Acids

Polyurethane adhesives provide excellent flexibility, impact resistance and durability. Polyurethanes are formed through the reaction of an isocyanate component with polyether or polyester polyols or other active hydrogen compounds. This paper refers to polyurethane adhesives made from polyester polyols with long aliphatic chains (up to 36 carbon atoms) and MDI (diphenylmethane-4,4’-diisocyanate). The polyester polyols have been made from dimer acids obtained from renewable sources and short chain diols. The polyols that were used presented different degrees of unsaturation. The influence of the different raw materials in the adhesives performance is studied. The polyurethanes were produced by reaction between quasi-stoichiometric quantities of polyol and MDI, at several temperatures. The reaction was carried under inert atmosphere and at temperatures below 100°C. Performance of the adhesives was tested by carrying adhesion, hardness and water absorption tests. Characterization of both the polyester polyols and polyurethane adhesives was carried by Fourier Transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC), Magnetic Nuclear Resonance (NMR), X-Ray Diffraction (WAXD), Scanning RMN Imaging of 1H of Stray- Field b (MRI) and Brookfield viscometry.

Characterization of Portuguese gypsums as raw materials for dermocosmetics

Clay Minerals ◽  
2019 ◽  
Vol 54 (3) ◽  
pp. 277-281 ◽  
Author(s):  
Cristiana Costa ◽  
António Fortes ◽  
Fernando Rocha ◽  
Angela Cerqueira ◽  
Delfim Santos ◽  
...  
Keyword(s):  
Calcium Sulfate ◽  
Raw Materials ◽  
Cement Industry ◽  
Oil Absorption ◽  
Chemical Quality ◽  
X Ray Diffraction ◽  
X Ray ◽  
White Cement ◽  
Wet Sieving

AbstractPortuguese gypsum deposits utilized by the cement industry were characterized mineralogically, chemically and technologically for possible application in dermocosmetics. The deposits studied (Loulé, Óbidos and Soure) correspond to small outcrops in diapiric anticline areas. In principle, they represent gypsites which are white, and generally of higher quality for traditional applications (e.g. white cement), or greyish, and generally not adequate for cements and mortars. The analytical methods used to characterize the materials were wet sieving and X-ray sedimentation, X-ray diffraction, X-ray fluorescence spectrometry and assessment of abrasiveness, plasticity, texturometrics (adhesivity and firmness), oil absorption and cooling rate. The Óbidos gypsum displayed greater mineralogical and chemical quality (almost pure calcium sulfate) and had a finer grain size (<63 μm), whereas Loulé and Soure gypsums contain mineralogical impurities (mainly quartz). The Óbidos gypsum shows good characteristics in general for application in dermocosmetics because of its absorption, plasticity, adhesivity, firmness and low abrasiveness.

scholarly journals Characterization of cordierite-mullite ceramics prepared from natural raw materials

2013 ◽  
Vol 6 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Abdulmula Ali Albhilil ◽  
Martin Palou ◽  
Jana Kozánková
Keyword(s):  
Thermal Shock Resistance ◽  
Raw Materials ◽  
X Ray Diffraction ◽  
X Ray ◽  
Mercury Intrusion ◽  
Before And After ◽  
Shock Resistance ◽  
Quenching Method ◽  
Mullite Ceramics

Abstract Series of six cordierite-mullite ceramics were synthesized via solid state reaction at various temperatures from 1250 °C for pure cordierite to 1500 °C for pure mullite. Then the samples were submitted to the test of thermal shock resistance based on cycling heating-quenching procedure. X-ray diffraction (XRD), Scanning electron microscopy (SEM) and Mercury intrusion porosimeter (MIP) have been used to characterize the samples before and after cycling heating-quenching method. Sample 6 was broken after 35 heating-quenching cycles, while the five other reminded stable. The refractoriness of samples is found to be higher than that of commercial ones. XRD shows that heating-quenching procedure has led to crystallization of cordierite and mullite phases. Apart from sample 6, the pore structure is stable with slight consolidation. The microstructure images confirm the results of XRD and MIP showing crack in sample 6 only, but compact and larger particles resulting from crystal growth in other samples due to the repeated action of heating.

scholarly journals Chemical and mineralogical characterization of portuguese ceramic tiles in the historic center of São Luís do Maranhão (Brazil): an approximation of the mineralogy and firing temperature of the raw materials

2013 ◽  
Vol 66 (1) ◽  
pp. 91-98 ◽  
Author(s):  
José Manuel Rivas Mercury ◽  
Domingos de Jesus Costa Pereira ◽  
Nazaré do Socorro Lemos Silva Vasconcelos ◽  
Aluísio Alves Cabral Jr. ◽  
Romulo Simões Angélica
Keyword(s):  
Firing Temperature ◽  
Raw Materials ◽  
X Ray Diffraction ◽  
Ceramic Tiles ◽  
Mineralogical Characterization ◽  
Calcium Carbonates ◽  
Historic Center ◽  
Mineral Phases ◽  
Materials Used

This work involved the first-ever characterization of antique Portuguese ceramic wall tiles in the Historic Center of São Luis do Maranhão, Brazil. The tiles were characterized by optical microscopy, X-ray diffraction (XRD) and chemical analysis to identify the possible raw materials used in the fabrication process, as well as the firing temperature of these materials. The results indicate that the microstructure of these materials consists of pores of varying sizes with calcite incrustations and quartz grain sizes smaller than 500 µm distributed in a pinkish yellow matrix, which were identified by XRD as calcite, gehlenite, wollastonite, quartz, and amorphous mineral phases. Based on this information, it can be inferred that the original raw materials probably consisted of a mixture of kaolinitic clays (Al2O3·2SiO2·2H2O) rich in calcium carbonates and quartz, or mixtures of kaolinitic clays, quartz and calcite, which did not reach the pre-firing temperature of 950ºC.

Synthesis and Characterization of PMMA/MMT Nanocomposites

2012 ◽  
Vol 182-183 ◽  
pp. 249-253
Author(s):  
Jun Qiao ◽  
Jia Wei Shen ◽  
Xiang Hong Huang ◽  
Qian Feng Zhang
Keyword(s):  
Methyl Methacrylate ◽  
Fourier Transformation ◽  
Raw Materials ◽  
Polymerization Process ◽  
X Ray Diffraction ◽  
X Ray ◽  
Fourier Transformation Infrared Spectroscopy ◽  
Thermal Stability Of

PMMA/MMT nanocomposites has been prepared by using methyl methacrylate (MMA), montmorillonite (MMT) and ethanolamine as the raw materials via an in-situ free radical polymerization process. The as-prepared nanocomposites were characterized by Fourier transformation infrared spectroscopy (FTIR), X-ray diffraction (XRD) and thermogravimetric analysis (TGA). The results show that the poly(methyl methacrylate) and inorganic montmorillonite have been effectively combined. The structure and thermal stability of the as-prepared nanocomposites are different from the content of MMT in the nanacomposites.

Synthesis and Characterization of α-Phase Silicon Nitride Powders by Direct Nitridation

2013 ◽  
Vol 631-632 ◽  
pp. 434-436
Author(s):  
Jiu Ming Liu ◽  
Jian Lei Wang ◽  
Shu Xia Ren
Keyword(s):  
Silicon Nitride ◽  
Raw Materials ◽  
X Ray Diffraction ◽  
Nitrogen Gas ◽  
Pure Nitrogen ◽  
X Ray ◽  
Α Phase ◽  
Heat Treated ◽  
Direct Nitridation

Using silicon powders as raw materials, adding nano-silicon nitride as a diluent and NH4Cl3 and FeCl3 as catalysts, α-phase silicon nitride powders were prepared by direct nitridation method. The silicon powders were first milled with 20% α-Si3N4 and 4% NH4Cl3 for 30 minutes. Then the mixture was heat-treated at 1300°C for 1 hour in the pure nitrogen gas. The phases and their content of the as-prepared product were detected by X-ray diffraction (XRD) and the microstructure was studied by scanning electron microscope (SEM). The results showed that the product mainly consisted ofα-Si3N4 with a mass fraction over 92% and were submicron-sized particles．

Synthesis and Characterization of Graphene/Cu2SnS3 Quantum Dots Composites

2012 ◽  
Vol 624 ◽  
pp. 59-62 ◽  
Author(s):  
Cai Xia Li ◽  
Jun Guo ◽  
Danyu Jiang ◽  
Qiang Li
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Quantum Dots ◽  
Raw Materials ◽  
Synthesis And Characterization ◽  
X Ray Diffraction ◽  
X Ray ◽  
Phase Structures ◽  
Transmission Electron

In this paper, employing Cu(AC)2•H2O, SnCl2•2H2O and thiourea as raw materials, the composites of graphene/Cu2SnS3 quantum dots (QDs) were prepared simply and quickly using the hydrothermal method. Meanwhile, the separate Cu2SnS3 QDs were also synthesized in the same way. The as-obtained Cu2SnS3 QDs and composites’ phase structures were analyzed and characterized by powder X-ray diffraction (XRD), and the results indicated that the size of the Cu2SnS3 QDs in the composites were less than that of the separate Cu2SnS3 QDs. At the same time, their morphologies were also observed and cross-confirmed by Transmission Electron Microscopy (TEM), and the measurements manifested that Cu2SnS3 QDs were uniformly dispersed on the surface of the graphene, while the separate Cu2SnS3 QDs have obvious glomeration. In addition to this, elemental analysis was also made to verify the existence of Cu2SnS3 on the surface of graphene.

scholarly journals Development and Properties of New Mullite Based Refractory Grog

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 779
Author(s):  
David Zemánek ◽  
Karel Lang ◽  
Lukáš Tvrdík ◽  
Dalibor Všianský ◽  
Lenka Nevřivová ◽  
...  
Keyword(s):  
Raw Materials ◽  
High Alumina ◽  
Firing Process ◽  
Chemical Compositions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Electron Microscopies ◽  
Alumina Refractory ◽  
Refractory Aggregate

The presented study is focused on optimization and characterization of a high-alumina refractory aggregate based on natural raw materials—kaolins, claystone, and mullite dust by-product (used to increase the alumina and mullite contents, respectively). In total, four individual formulas with the Al2O3 contents between 45 and 50 wt.% were designed; the samples were subsequently fired, both in a laboratory oven and an industrial tunnel furnace. The effects of repeated firing were examined during industrial pilot tests. Mineral and chemical compositions and microstructures, of both the raw materials and designed aggregates, were thoroughly investigated by the means of X-ray fluorescence spectroscopy, powder X-ray diffraction, and optical and scanning electron microscopies. Porosity, mineral composition, and mullite crystal-size development during the firing process were also studied. Based on the acquired results, the formula with the perspective to be used as a new mullite grog, featuring similar properties as the available commercial products, however, with reduced production expenses, was selected. The quality of grog determines to a large extent the properties of the final product. Hence, optimization of aggregates for specific refractories is of a great importance. The production of engineered aggregates provides the opportunity to utilize industrial by-products.

scholarly journals Analisis Mineralogi dan Kimia Dolomit Kabupaten Bone Bolango, Provinsi Gorontalo

2021 ◽  
Vol 9 (2) ◽  
pp. 95-102
Author(s):  
Sufriadin Sufriadin ◽  
Purwanto Purwanto ◽  
Muhammad Rahmatul Jihad ◽  
Astina Aras ◽  
Angelia Santoso ◽  
...  
Keyword(s):  
Raw Materials ◽  
Xrd Analysis ◽  
Chemical Compositions ◽  
Content Increase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Agriculture Sector ◽  
Selective Mining ◽  
Fluorescence Spectrometer

Characterization of dolomite samples from Bone Bolango, Gorontalo Province have been performed with the objective to find out their mineralogical and chemical compositions. Observation and mineral analyses were carried out by means of microscopy and X-ray diffraction methods respectively; whereas chemical composition was determined by using X-ray fluorescence spectrometer. Result of XRD analysis shows that samples contain dolomite [CaMg(CO3)2], calcite [CaCO3] and [SiO2]. The proportion of dolomite is about 60.4% in average and its presence is as replacement of calcite in bioclast components and matrices in the rock. Dolomite crystals are characterized by mosaic texture with euhedral – subhedral in shapes. Spacially, dolomite content increase from west to the east of study area. The XRF analysis reveals that dolomite samples contain MgO ranging between 8.07 and 20.78% while CaO ranges between 30.04 and 56.13%. The SiO2 concentration ranges from 3.50 – 7.55%; whereas Al2O3 ranges from 1.07 – 1.84%. The average MgO content of dolomite about 12.89% can be categorized as calcium dolomite. Dolomite within the study area can be used directly in agriculture sector, but it less suitable as raw materials in glass, ceramic and refractory industries because the average content of MgO is less than 17%. However, it can be increased of their MgO with the application of selective mining or beneficiation process.

scholarly journals CHEMICAL-MINERАLOGICAL CHARACTERIZATION OF BAUXITES FROM DIFFERENT DEPOSITS

2014 ◽  
Vol 5 (1) ◽  
Author(s):  
Gordana Оstojić ◽  
Dragica Lazić ◽  
Branko Škundrić ◽  
Jelena Penavin Škundrić ◽  
Slavica Sladojević ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Thermal Analysis ◽  
Raw Materials ◽  
Mineralogical Composition ◽  
Chemical Characteristics ◽  
X Ray Diffraction ◽  
X Ray ◽  
Scanning Electron

From the aspect of their chemical and mineralogical composition, bauxites are very complex multicomponent raw materials. The paper presents the characterization of bauxite from several different deposits: Brazil, Milići, Čitluk and Kosovo. Chemical characteristics were determined by a combination of different analytical methods: gravimetry, potentiometric titration, atomic absorption spectroscopy (AAS) and UV-VIS spectrophotometry. Mineralogical composition was determined using X-ray diffraction and thermal analysis methods. Chemical and structural characterization is complemented by the results of scanning electron microscopy with EDX analysis. The information obtained was used for the assessment of the quality of investigated bauxites from the aspect of their application in the production of alumina.

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