Influence of temperature on structural-phase changes and physical properties of ceramics on the basis of aluminum oxide and silicon

2020 ◽  
Vol 62 (7) ◽  
pp. 716-720
Author(s):  
N. Kantay ◽  
N. Kasmamytov ◽  
B. Rakhadilov ◽  
S. Plotnikov ◽  
M. Paszkowski ◽  
...  

Abstract The purpose of this experiment was to prepare high-voltage porcelain ceramics as local raw materials. Density, water absorption, and volume shrinkage were determined according to the State standard (GOST 7025-91). A structural analysis was carried out using a scanning electron microscope, and an X-ray phase analysis was carried out on an Xpert PRO diffractometer. It was found, that in the initial state, ceramics consist of hexagonal (SiO2) and a small amount of monoclinic phase. Above a temperature of 1150 °С they consist of hexagonal (SiO2), an orthorhombic lattice, and also contain mullite (Al2Si2O13).

2019 ◽  
Vol 9 (20) ◽  
pp. 4422 ◽  
Author(s):  
Jianjun Hu ◽  
Chuan He ◽  
Xian Yang ◽  
Hui Li ◽  
Hongbin Xu ◽  
...  

The FeS solid lubricating coatings were prepared on the AISI 5140 steel by chemical bath deposition (CBD) coating technique at various temperatures from 30 to 90 °C. The influence of temperature on microstructure, microcracks, and tribological properties was characterized and studied by X-ray diffraction (XRD), scanning electron microscope (SEM), and energy dispersive spectrometry (EDS). The results show that the coating mainly consists of FexSy (FeS, FeS2, and Fe1−xS), and has a chrysanthemum-shaped (CS) morphology composed of the FeS crystal petals. The CS particles nucleate at about 30 °C, rapidly grow and reach a peak thickness at about 50–70 °C, and finally disappear and are replaced by disordered thick petals at 90 °C. The wear resistance of the steel was improved obviously after introducing of FeS coatings, owing to that the coatings can provide better lubrication and improve the wear resistance.


2020 ◽  
Vol 74 (10) ◽  
pp. 1280-1286
Author(s):  
Lucas Train Loureço ◽  
Celso de Araujo Duarte ◽  
Dietmar William Foryta ◽  
Bruno Guimarães Titon ◽  
Eleonora Maria Gouvêa Vasconcellos

The present work reports the results of structural and optical investigations in samples of natural dolomite, subjected to thermal treatment at different temperatures (500 ℃ to 700 ℃) and times (one up to three hours). The motivation is the evaluation of the changes that may occur in carbonaceous asteroids and meteorites, respectively, subjected to the action of the solar radiation and heated during the fall in the atmosphere. We carried out scanning electron microscopy, electron dispersive spectroscopy, X-ray diffraction, optical reflectance and photoluminescence measurements


2011 ◽  
Vol 399-401 ◽  
pp. 788-791 ◽  
Author(s):  
Wen Jie Yuan ◽  
Jun Li ◽  
Chao Pan ◽  
Cheng Ji Deng ◽  
Hong Xi Zhu

In Al-Si-C system, there are many compounds, of which Al4SiC4 is useful as high-temperature structure material and the antioxidant in carbon-containing refractory. In this paper, Al4SiC4 powders were synthesized by using kaolin grog, aluminum and activated carbon as raw materials. The phase changes of the synthesized samples were examined by X-ray diffraction (XRD), and the microstructure was observed by scanning electron microscope (SEM). The effects of synthesis temperature and the proportion of aluminum on phase compositions of Al-Si-C system were investigated. The results show plate-like Al4SiC4 powders can be prepared with optimal ratio of starting materials and synthesis temperature.


2020 ◽  
Vol 62 (7) ◽  
pp. 716-720
Author(s):  
Nurgamit Kantay ◽  
Nurdek Kasmamytov ◽  
Bauyrzhan Rakhadilov ◽  
Sergey Plotnikov ◽  
Maciej Paszkowski ◽  
...  

2011 ◽  
Vol 117-119 ◽  
pp. 769-772
Author(s):  
Yin Jie Wang ◽  
Ji Ping Liu ◽  
Mei Xiu Kan ◽  
Xiao Bing Lu

Use the Monoclinic phase of nano-scale ZrO2 , Li2ZrO3 and MgO as raw materials, with high temperature solid state reaction, we synthesized the Lithium zirconate materials which can directly absorb CO2 at high temperatures of 450~550°C. Then use the scanning electron microscopy (SEM) and X-ray diffraction (XRD) for the morphology and structure analysis. The CO2 absorption properties were tested by thermal analyzer (TG). The experimental results showed that the amount of MgO addition affected the Lithium zirconate’s CO2 absorption properties, but to the pH and surface area, there is on influence.


1992 ◽  
Vol 267 ◽  
Author(s):  
Ana M De Andres ◽  
Isabel MuÑOZ

ABSTRACTNineteen roman ceramic sherds found near Salobreña (Granada, Spain), in the western coast of the Mediterranean Sea, as well as different ceramic clays from the surroundingsare studied. Both clays and ceramic sherds are characterizad by X-ray diffraction and spectrometry, differential thermal analysis, and scanning electron and optical microscopies. A good number of the ceramic pieces, among which some “Terrae Sigillatae”, have a composition similar to that of the local clays and, thus, have been probably manufactured at Salobreña. Only a few of them have a foreign origin. For most of them, the firing temperature was about 800-850 °C, although some have been produced at 900-1000 °C, and some others at 1000-1100 °C. It is concluded that Salobreña appearsto have been an important settlement just in the third century of the Christian era.


2011 ◽  
Vol 236-238 ◽  
pp. 1712-1716 ◽  
Author(s):  
Hai Tao Liu ◽  
Jun Dai ◽  
Jia Jia Zhang ◽  
Wei Dong Xiang

Bismuth selenide (Bi2Se3) hexagonal nanosheet crystals with uniform size were successfully prepared via a solvothermal method at 160°C for 22 h using bismuth trichloride(BiCl3) and selenium powder(Se) as raw materials, sodium bisulfite(NaHSO3) as a reducing agent, diethylene glycol(DEG) as solvent, and ammonia as pH regulator. Various techniques such as X-ray diffraction (XRD), field-emission scanning electron microscope (FESEM), high-resolution transmission electron microscope (HRTEM), and selected area electron diffraction (SAED) were used to characterize the obtained products. Results show that the as-synthesized samples are pure Bi2Se3 hexagonal nanosheet crystals. A possible growth mechanism for Bi2Se3 hexagonal nanosheet crystals is also discussed based on the experiment.


2021 ◽  
Vol 325 ◽  
pp. 181-187
Author(s):  
Martin Nguyen ◽  
Radomír Sokolář

This article examines the influence of fly ash on corrosion resistance of refractory forsterite-spinel ceramics by molten iron as a corrosive medium. Fly ash in comparison with alumina were used as raw materials and sources of aluminium oxide for synthesis of forsterite-spinel refractory ceramics. Raw materials were milled, mixed in different ratios into two sets of mixtures and sintered at 1550°C for 2 hours. Samples were characterized by X-ray diffraction analysis and thermal dilatometric analysis. Crucibles were then made from the fired ceramic mixtures and fired together with iron at its melting point of 1535°C for 5 hours. The corrosion resistance was evaluated by scanning electron microscopy on the transition zones between iron and ceramics. Mixtures with increased amount of spinel had higher corrosion resistance and mixtures with fly ash were comparable to mixtures with alumina in terms of corrosion resistance and refractory properties.


Cerâmica ◽  
2018 ◽  
Vol 64 (372) ◽  
pp. 570-576
Author(s):  
B. Ngayakamo ◽  
S. E. Park

Abstract This study evaluated the potential of locally sourced-ceramic raw materials in Tanzania, Pugu kaolin, Same clay, vermiculite and feldspar, for production of high voltage porcelain insulators. The chemical, mineral phases and microstructural characterization of raw materials and porcelain samples were carried out using the X-ray fluorescence, X-ray diffraction, and scanning electron microscopy techniques, respectively. The mineral phases of the fired porcelain sample identified were mullite and quartz. The porcelain bodies were fabricated using the dry pressing method by varying the composition of the selected ceramic raw materials. The physical-mechanical properties and dielectric strength were measured for each porcelain sample. The sample with the composition of 20% Pugu kaolin, 20% Same clay, 20% vermiculite and 40% feldspar was found to have the dielectric strength of 50.8 kV.mm-1, bending strength of 20 MPa and water absorption of 0.46%, which satisfies the main requisite properties for high voltage porcelain insulators.


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