PRODUCTION OF SYNTHETIC WOLLASTONITE BASED ON PHOSPHORIC SLAG AND AMORPHOUS SILICA PRODUCED BY "SOLAR" SILICON

Mapping Intimacies ◽

10.34708/gstou.conf..2021.54.99.031 ◽

2021 ◽

Author(s):

В.Ф. Вернер ◽

Т.М. Худякова ◽

Б.К. Сарсенбаев ◽

А.М. Шакей ◽

Г.Р. Сауганова

Keyword(s):

Amorphous Silica ◽

Impurity Phases ◽

Synthetic Wollastonite ◽

Solar Silicon

В статье приведены результаты исследований по получению синтетического волластонита на основе фосфорного шлаке и аморфного кремнезема от производства солнечного кремния. Установлено, что корректировка электротермофосфорного шлака аморфным кремнеземом от производства «солнечного» кремния облегчает процесс волластонитообразования, смещая его в область более низких температур 800-950оС и минимизирует количество примесных фаз при температурах 1000-1050оС устойчивого существования игольчатого волластонита. The article presents the results of research on the production of synthetic wollastonite based on phosphoric slag and amorphous silica from the production of solar silicon. It is established that the correction of electrothermophosphoric slag with amorphous silica from the production of "solar" silicon facilitates the process of wollastonite formation, shifting it to the region of lower temperatures of 800-950oC and minimizes the number of impurity phases at temperatures of 1000-1050oC for the stable existence of needle wollastonite.

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Amorphous silica coating on α-alumina particles

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100137422 ◽

1995 ◽

Vol 53 ◽

pp. 210-211

Author(s):

J. W. Mellowes ◽

C. M. Chun ◽

I. A. Aksay

Keyword(s):

Amorphous Silica ◽

Heterogeneous Nucleation ◽

Homogeneous Nucleation ◽

Silica Coating ◽

Full Density ◽

Optimal Conditions ◽

Fine Grained ◽

Alumina Particles ◽

Complete Mullitization ◽

Powder Compacts

Mullite (3Al2O32SiO2) can be fabricated by transient viscous sintering using composite particles which consist of inner cores of a-alumina and outer coatings of amorphous silica. Powder compacts prepared with these particles are sintered to almost full density at relatively low temperatures (~1300°C) and converted to dense, fine-grained mullite at higher temperatures (>1500°C) by reaction between the alumina core and the silica coating. In order to achieve complete mullitization, optimal conditions for coating alumina particles with amorphous silica must be achieved. Formation of amorphous silica can occur in solution (homogeneous nucleation) or on the surface of alumina (heterogeneous nucleation) depending on the degree of supersaturation of the solvent in which the particles are immersed. Successful coating of silica on alumina occurs when heterogeneous nucleation is promoted and homogeneous nucleation is suppressed. Therefore, one key to successful coating is an understanding of the factors such as pH and concentration that control silica nucleation in aqueous solutions. In the current work, we use TEM to determine the optimal conditions of this processing.

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Entrapment of trans, trans-farnesol in amorphous silica capsules and its release behaviour: On the route of futur applications

Planta Medica ◽

10.1055/s-0032-1321307 ◽

2012 ◽

Vol 78 (11) ◽

Author(s):

FL Sousa ◽

M Santos ◽

SM Rocha ◽

T Trindade

Keyword(s):

Amorphous Silica

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Mechanoactivation Of Rice Husk Ash In Laboratory Conditions

Promyshlennoe i Grazhdanskoe Stroitel stvo ◽

10.33622/0869-7019.2019.11.20-26 ◽

2019 ◽

pp. 20-26

Keyword(s):

Mechanical Activation ◽

Rice Husk ◽

Amorphous Silica ◽

Silicon Oxide ◽

Rice Husk Ash ◽

Pozzolanic Activity ◽

Maximum Solubility ◽

Laboratory Conditions ◽

Before And After ◽

Mineral Additive

In many rice producing countries of the world, including in Vietnam, various research aimed at using rice husk ash (RHA) as a finely dispersed active mineral additive in cements, concrete and mortars are being conducted. The effect of the duration of the mechanoactivation of the RHA, produced under laboratory conditions in Vietnam, on its pozzolanic activity were investigated in this study. The composition of ash was investigated by laser granulometry and the values of indicators characterizing the dispersion of its particles before and after mechanical activation were established. The content of soluble amorphous silicon oxide in rice husk ash samples was determined by photocolorimetric analysis. The pizzolanic activity of the RHA, fly ash and the silica fume was also compared according to the method of absorption of the solution of the active mineral additive. It is established that the duration of the mechanical activation of rice husk ash by grinding in a vibratory mill is optimal for increasing its pozzolanic activity, since it simultaneously results in the production of the most dispersed ash particles with the highest specific surface area and maximum solubility of the amorphous silica contained in it. Longer grinding does not lead to further reduction in the size of ash particles, which can be explained by their aggregation, and also reduces the solubility of amorphous silica in an aqueous alkaline medium.

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Control of the phase composition of advanced calcium phosphates using an x-ray diffractometer with a curved position-sensitive detector

Industrial laboratory Diagnostics of materials ◽

10.26896/1028-6861-2020-86-6-29-35 ◽

2020 ◽

Vol 86 (6) ◽

pp. 29-35

Author(s):

V. P. Sirotinkin ◽

O. V. Baranov ◽

A. Yu. Fedotov ◽

S. M. Barinov

Keyword(s):

Phase Composition ◽

Calcium Phosphates ◽

Position Sensitive Detector ◽

Sensitive Detector ◽

X Ray Diffraction ◽

X Ray ◽

Impurity Phases ◽

Position Sensitive ◽

Diffraction Peaks ◽

Diffraction Patterns

The results of studying the phase composition of advanced calcium phosphates Ca10(PO4)6(OH)2, β-Ca3(PO4)2, α-Ca3(PO4)2, CaHPO4 · 2H2O, Ca8(HPO4)2(PO4)4 · 5H2O using an x-ray diffractometer with a curved position-sensitive detector are presented. Optimal experimental conditions (angular positions of the x-ray tube and detector, size of the slits, exposure time) were determined with allowance for possible formation of the impurity phases during synthesis. The construction features of diffractometers with a position-sensitive detector affecting the profile characteristics of x-ray diffraction peaks are considered. The composition for calibration of the diffractometer (a mixture of sodium acetate and yttrium oxide) was determined. Theoretical x-ray diffraction patterns for corresponding calcium phosphates are constructed on the basis of the literature data. These x-ray diffraction patterns were used to determine the phase composition of the advanced calcium phosphates. The features of advanced calcium phosphates, which should be taken into account during the phase analysis, are indicated. The powder of high-temperature form of tricalcium phosphate strongly adsorbs water from the environment. A strong texture is observed on the x-ray diffraction spectra of dicalcium phosphate dihydrate. A rather specific x-ray diffraction pattern of octacalcium phosphate pentahydrate revealed the only one strong peak at small angles. In all cases, significant deviations are observed for the recorded angular positions and relative intensity of the diffraction peaks. The results of the study of experimentally obtained mixtures of calcium phosphate are presented. It is shown that the graphic comparison of experimental x-ray diffraction spectra and pre-recorded spectra of the reference calcium phosphates and possible impurity phases is the most effective method. In this case, there is no need for calibration. When using this method, the total time for analysis of one sample is no more than 10 min.

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