Characterization of silica polymorphs in kaolins by X-ray diffraction before and after phosphoric acid digestion and thermal treatment

2005 ◽  
Vol 552 (1-2) ◽  
pp. 201-206 ◽  
Author(s):  
Sibel Kahraman ◽  
Müşerref Önal ◽  
Yüksel Sarıkaya ◽  
İhsan Bozdoğan
2019 ◽  
Vol 33 (12) ◽  
pp. 1950111 ◽  
Author(s):  
Mihai Todica ◽  
Zoltan Kovacs-Krauss ◽  
Carmen Niculaescu ◽  
Marieta Mureşan-Pop

The modification of local structure of some commercial polyethylene terephthalate (PET) samples, gamma irradiated at different doses, was investigated by X-ray diffraction method before and after thermal treatment. Before the thermal treatment, the samples exposed to different doses of gamma radiations, does not show noticeable structural changes. However, the gamma exposure affects the thermal behavior of samples submitted to melting–cooling process. These modifications have been highlighted by X-ray diffraction, and confirmed also by thermal analysis and electron spin resonance spectroscopy.


2015 ◽  
Vol 659 ◽  
pp. 127-131
Author(s):  
Usanee Malee ◽  
Sakdiphon Thiansem

The scientific process was used to explain characterization and physical properties of the clay sample close to the ancient Nan kiln site. These samples were obtained from JQA, FQB, PQC and NQD. X-ray diffraction (XRD) and X-ray fluorescence (XRF) technique were used to determine the chemical composition and phase transformation before and after fired at 800-1250 °C. XRF result was confirmed that all clay samples mainly contained SiO2(>80 wt. %) XRD pattern indicated that quartz was the majority of phase in the all of them. High amount of Fe2O3(>1.6 wt. %) was related to the red-brown tone color. The clay sample could be fired up to 1280 °C without wrapping behavior; it was found that FQB clay had the highest firing resistance due to the maximum quartz content.


2014 ◽  
Vol 775-776 ◽  
pp. 97-101
Author(s):  
Loanda Raquel Cumba ◽  
U.O. Bicalho ◽  
D.R. Carmo

This paper describes the preparation and complementary characterization of a composite formed from the activation of titanium isopropoxide by phosphoric acid and deionized water (TiP).Techniques such as, X-ray diffraction (XRD), Raman , electronic (UV-vis) and Scanning electron microscopies (SEM) were used for characterization of this new composite formed. In the X-ray diffractogram of TIP was observed four intense peaks. A strong absorption was observed in the region 362-445 nm. The scanning electron microscopy of TiP, shows that the prepared material consists mostly of a cluster of spherical particles with diameters ranging from 2.35 to 2.60 μm.


2021 ◽  
Author(s):  
Joanna Hrabia-Wiśnios ◽  
Beata Leszczyńska-Madej ◽  
Marcin Madej ◽  
Aleksandra Węglowska

Abstract The paper presents the results of research on the microstructure and selected mechanical properties of the SnSbCu bearing alloy after friction stir processing (FSP). The Whorl tool was used for modification; the process was carried out using two rotational speeds of the tool: 280 and 450 RPM and a constant linear speed of 355 mm/min. Microstructure studies were performed employing the techniques of light microscopy and scanning electron microscopy along with analysis of the chemical composition of micro-areas. Additionally, the phase composition was investigated by means of the X-ray diffraction method and statistical analysis of the precipitates present in the investigated alloy. In addition, hardness, flexural strength and uniaxial compression tests were performed before and after FSP modification. It was proved that using FSP to modify the SnSbCu alloy promotes refinement and homogenization of the microstructure, as well as improvement of the flexural strength, whereas no changes in the hardness level were found.


2012 ◽  
Vol 591-593 ◽  
pp. 1113-1116
Author(s):  
Si Chen Cheng ◽  
Yin Zheng Liang ◽  
Yi Ping Qiu

The electrospinning technique was used to produce poly (vinylidene fluoride) (PVDF) membrane. Thermal treatment was introduced to improve the mechanical property and dimensional stability. In this paper, the PVDF membranes before and after thermal treatment were characterized by Scanning electron microscope (SEM), differential scanning calorimeter (DSC) and wide angle X-ray diffraction (WAXD), tensile testing. The crystallinity, tensile property, as well as melting temperature changed with the treated temperature. The results hows that thermal treatment could notably increase the tensile property of electrospun PVDF membrane and 160°C is a proper temperature for thermal treating


2013 ◽  
Vol 6 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Abdulmula Ali Albhilil ◽  
Martin Palou ◽  
Jana Kozánková

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.


2017 ◽  
Vol 262 ◽  
pp. 487-491 ◽  
Author(s):  
Sina Ghassa ◽  
Hadi Abdollahi ◽  
Mahdi Gharabaghi ◽  
Saeed Chehreh Chelgani ◽  
Mohammad Jafari

The mineral surface chemistry characterization is essential to describe the dissolution kinetics in leaching and bioleaching. Five different methods, including X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray Spectroscopy (EDS), Fourier Transform Infrared Spectroscopy (FTIR) and Raman Spectroscopy, have been applied to study the surface chemistry changes during pyrite, sphalerite and molybdenite bioleaching. The surface characterizations have been done for samples before and after biological and chemical leaching. The SEM images illustrated that the minerals surfaces were smooth before processing, while they covered with an ash layer after biological treatment. Although EDS analysis and Raman spectrum demonstrated the potassium jarosite formation on the pyrite surface during bioleaching, the formation of jarosite layer did not occur on the sphalerite surfaces during bioleaching. On the other hand, a sulfur layer formation on the sphalerite surface was confirmed by mentioned characterization methods. Finally, according to the XRD and EDS spectrum the molybdenite surface had been covered both with sulfur and jarosite.


2019 ◽  
Vol 280 ◽  
pp. 04003
Author(s):  
Agus Mirwan ◽  
Meilana Dharma Putra ◽  
Riani Ayu Lestari

The existence of peat clay is scattered in many parts of the world with the huge amount. The high compound of minerals in the peat clay can be potentially used as adsorbent and catalyst. This research aims to study the composition of peat clay and functional group of the compound in the peat clay. The characterization of x-ray fluorescence (XRF), fourier transform infrared spectroscopy (FTIR), x-ray diffraction (XRD), and scanning electron microscope-energy dispersive x-ray (SEM- EDX) were assigned to compare the sample before and after calcination process at 700 oC 120 min. FTIR analysis showed the presence of quartz, kaolinite, hematite, illite in peat clay. The results of XRF analysis showed that chemical composition of peat clay was dominantly in the form of silica oxide (18%), aluminum oxide (7%), and iron oxide (15%). The amount of compounds was observed to increase to be 32%, 18% and 11%, respectively after calcinations. XRD analysis confirmed the presence of this mineral in the peat clay. SEM analysis showed flake structure of peat clay with EDX which indicated composition of the dominant element namely the presence of Al, Si, and Fe before and after calcination. This high amount of minerals in peat clay led to potential source to be utilized as adsorbent for removing the pollutant or as and catalyst for chemical process.


2016 ◽  
Vol 35 (7) ◽  
pp. 723-728 ◽  
Author(s):  
Sousan Gholamrezaei ◽  
Masoud Salavati-Niasari ◽  
Hassan Hadadzadeh ◽  
Mohammad Taghi Behnamfar

AbstractMagnetic Co3O4nanostructures were synthesized via a facile thermal treatment method at 700°C by usingtrans-Na[Co(HMTA)2(NO2)4].H2O as a new precursor. In synthetic process Co-complex was prepared by the reaction of Na3[Co(NO2)6] and hexamethylenetetramine (HMTA). Results show that the target Co-complex was synthesized successfully and provides good conditions for preparation of magnetic nanostructures in a facile and surfactant-free method to prepare the octahedral nanostructures. Precursors and nanostructures were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), UV–visible, Fourier transform infrared (FTIR) spectroscopy and alternating gradient force magnetometer (AGFM). It is found that the Co3O4nanostructures exhibit a ferromagnetic behavior with a saturation magnetization of 8.69 emu/g and a coercivity of 305.3 Oe at room temperature.


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