Silicon Oxide Content Research Articles

Studying the Kinetics of the Alkaline Processing of Boron Production Wastes under Different Conditions

The kinetics are studied of topochemical reactions of the formation of calcium hydrosilicate in a multicomponent aqueous system consisting of waste products of boric acid production. The waste products include silicon dioxide and calcium sulfate in equal molar fractions, an alkali metal hydroxide in a stoichiometric ratio to the molar content of calcium sulfate and silicon oxide for obtaining hydrosilicate calcium, and the volume of water calculated to obtain a solution of alkali metal sulfate with a concentration below saturation. Data are obtained on the kinetics of the formation of calcium hydrosilicates in different modes of processing (normal conditions with constant stirring; ultrasonic action at a temperature of 20°C; microwave exposure with constant stirring at a temperature of 95°C; and autoclaving at a temperature of 220°C). It is found that the fastest reaction rate is characteristic of microwave treatment, and the largest proportion of reacted alkali metal hydroxide is obtained during autoclave treatment.

Defect Analysis and Reliability Characteristics of (HfZrO₄)1-x(SiO₂)x High-κ Dielectrics.

Hafnium zirconium silicon oxide ((HfZrO₄)1-x(SiO₂)x) materials were investigated through the defect analysis and reliability characterization for next generation high-κ dielectric. Silicate doped hafnium zirconium oxide (HfZrO4) films showed a reduction of negative flat-band voltage (Vfb) shift compared to pure HfZrO₄. This result was caused by a decrease in donor-like interface traps (Dit) and positive border traps (Nbt). As the silicon oxide (SiO₂) content increased, the Vfb was shifted in the positive direction from -1.23 to -1.10 to -0.91 V and the slope of the capacitance-voltage (C-V) curve increased. The nonparallel shift of the C-V characteristics was affected by the Dit, while the Nbt was responsible for the parallel C-V curve shift. The values of Dit reduced from 4.3 × 1011, 3.5 × 1011, and 3.0 × 1011 cm-2eV-1, as well as the values of Nbt were decreased from 5.24, 3.90 to 2.26 × 1012 cm-2. Finally, reduction of defects in the HfZrO₄-base film with an addition of SiO₂ affected the gate oxide reliability characteristics, such as gate leakage current (JG), bias temperature stress instability (BTSI), and time dependent gate dielectric breakdown (TDDB).

Municipal solid waste (MSW) - competitive raw materials for combustible materials obtaining

Waste-to-energy projects can be classified as a complementary technology for energy recovery from nonrecyclable municipal waste fractions and should therefore not compete with measures to reduce, reuse, and recycle materials. The article presents the characterization of some treated municipal solid wastes as competitive raw materials for combustible materials obtaining. Samples with lignocellulosic and polymeric composition were analyzed, namely 3 samples of SRFs (solid recovered fuels) used as secondary raw material in cement plants, SRF1, SRF2, SRF3; a sample of RDF, consisting of household waste; a sample of fluff (a homogeneous mixture of non-hazardous waste - selected, mechanically treated and dried) used as a secondary raw material in cement plants; 4 samples of municipal solid waste, fractions smaller than 100 mm, after a bio-drying process, with composition: paper and cardboard (70-80%), wood (6-15%), plastic (6-10%), glass and metal (3-14%), MBU1, MBU2, MBU3, MBU4. The waste samples were characterized in terms of technical and elementary characteristics and the ash (obtained by the sample incineration) behavior in the combustion process. The mineral matter was investigated by the X-ray fluorescence analytical technique using the Rigaku CG X-ray Spectrofluorimeter. The analysis of the indices used for the slagging and deposit formation risks evaluation shows that the analyzed samples present an obvious risk of melt formation and deposits, due to a high content of base oxides and silicon oxide.

Effects of Grog Additions on Some Refractory Properties of Raw (Abusoro) Kaolin Clay Deposit for Furnace Lining

The influence of the weight of grog on some refractory properties of raw Abusoro clay samples found in Abusoro Village, Ondo State, Nigeria was evaluated. These samples were presented for refractory tests (apparent porosity, linear shrinkage, refractoriness, bulk density and cold crushing strength). The weights of the grog were varied from 20-40 wt. % in the blend. The chemical and microstructural examinations of the untreated alumino-silicate Abusoro clay samples indicated that they are abundant in silica, SiO2 (62.74wt. %) and alumina, Al2O3 (31.42wt. %). Other minor compounds found are Fe2O3 (1.43%), K2O (0.30%) with no trace amounts of MgO (0.00); therefore, they are regarded as alumino-silicate. Particular observation is made on MgO with zero amounts and the total of K2O + Na2O + MgO which are less than 2% in the clay samples. These results signify that the clay possesses high viability for manufacturing of refractory bricks, pulp and paper, ceramics, fertilizers, paint and cement. The performance evaluations of the refractory bricks measured indicated acceptable and satisfactory results vis-à-vis standard refractory properties for refractory fireclay bricks. However, the apparent porosity (43.2%) and CCS (21.21MPa) obtained for Abusoro clay sample at 30% weight of grog may as well be suitable for insulating refractory applications. The high apparent porosity could be an indication of high content of silicon oxide in the raw clay.

The impact of crystallite size of naturally occurring and synthetic wollastonite on its modifying effect in epoxy coatings

The efficiency of application and finiteness of raw material supply base of naturally occurring wollastonite leads to the fact that the synthesis of this filler on the base of available renewable raw material, for example, rice husk, is of actual importance. Depending on the ratio of calcium carbonate : silicon oxide (received from rice husk), synthetic wollastonite could have different phase constitution. It consists mainly of pseudowollastonite and wollastonite. Other silicates of lime, for example, larnite, could be also present in its composition. The maximum content of wollastonite was registered in the sample with the ratio CaCO3:SiO2=1.2:1 and it is significantly lower than of naturally occurring mineral Miwoll 10-97. Naturally occurring wollastonite demonstrates the highest modifying effect, from the perspective of wear reduction and harshness enhancement of epoxy coatings. Synthetic wollastonite obtained at the ratio CaCO3:SiO2=1.2:1 is slightly less efficient. Along with that, there could be observed the regularity that the larger the crystallite size of wollastonite, the higher its abrasion resistance and harshness of filled epoxy coatings. When the content of silicon oxide in the composition of synthetic wollastonite grows, the size of its crystals has a tendency to decrease. Given this, the synthesis of wollastonite should be directed towards the enlargement of its crystals size, i.e. it is recommended to increase the content of calcium carbonate in its composition and to lower fusion temperature in order to reduce pseudowollastonite formation.

Self-diffusion in ionic liquids with nitrate anion: Effects of confinement between glass plates and static magnetic field

Alkylammonium nitrate protic ionic liquids (ILs), when placed between flat polar borosilicate glass plates, have demonstrated enhanced diffusivity and the gradual decrease of diffusivity after exposure to an external static magnetic field (Filippov et al., 2018). This phenomenon has been explained by phase transformations taking place in the ILs. In this study, we observed similar processes occurring in systems prepared with ethylammonium nitrate confined between quartz plates. A higher content of silicon oxide in the plates does not significantly alter the phenomenon previously found in the system prepared with borosilicate glass plates. For the first time, we have observed similar effects of confinement and magnetic field on the aprotic IL, 1‑ethyl‑3‑methylimidazolium nitrate. Substitution of the ethylammonium cation with a 1‑ethyl‑3‑methylimidazolium cation slows down the kinetics and increases magnitude of the processes occurring in the IL exposed to a magnetic field. We suggested that the main factor determining these effects is the presence and modification of the hydrogen-bonding network in the studied protic and aprotic ILs. The process of inverse phase transformation for the confined ethylammonium nitrate after removing the sample from the magnetic field was observed and analysed.

New discoveries in the growth of SiC whiskers derived from hydrogen silicone oil

The SiC whiskers were prepared on carbon matrix by high hydrogen-containing silicone oil (H-PSO) as raw materials. Based on the results of previous experiments, we further studied the effect of non-heat treatment factor on growth of SiC whiskers, including type and thickness of carbon matrix, size of embedded powders, and growth catalysts. The results showed that the powder particle size and the matrix should be properly matched to facilitate whisker growth. When grown on 2 mm graphite plate, the particle size was 150 μm-180 μm, the SiC whiskers were straight, smooth and homogeneous, showing hexagonalprisms morphology, which were bounded by low-energy (1 1 1) planes, rather than silicon oxide coating. The change of particle size led to the change of concentration of reaction gas and partial pressure of oxygen, which resulted in the difference content of silicon oxide in whiskers, showing hexagonalprisms or cylindrical morphology. Adding growth catalyst, the whisker morphology was not as good as the whisker grown without catalyst, and the growth mechanism had changed.

Acid-base properties of silicon-containing compounds isolated from horsetails (<i>Equisetum Equisetaceae</i>)

The results of a study into the acid-base surface properties of four silicon-containing ash samples obtained from the above-ground part of the field horsetail plant species ( E. arvense L. ) are presented. The samples were derived according to various schemes, comprising oxidative roasting both with and without preliminary treatments involving water and solutions of hydrochloric acid having a concentration of 0.1 and 1.0 mol/l. It was shown that the content of silicon dioxide in the samples varies from 33 to 98 % depending on the conditions of processing of raw materials. Preliminary processing of the raw material with an acid solution prior to roasting results in the formation of ash having a high silicon oxide content. The main impurity elements are calcium, potassium, magnesium, aluminum and iron. Samples prepared without preliminary treatment, as well as those treated with water, are characterised by a large amount of alkaline earth metal- and potassium oxides. A comparative characteristic of the surface condition of the obtained ash samples is given using pH measurements and the Hammett acidity function method. The pH measurements allow the integral acidity of the surface to be evaluated, while the Hammett method, based on the selective adsorption of acid-base indicators, is used to study the distribution of surface centres by acid-base properties. The pH values of the aqueous suspensions of neutral, alkaline or acidic samples are determined depending on the plant tissue processing scheme. It was found that the surface of the samples is characterised by the presence of Lewis acid- (pKa +16.8), Bronsted basic- (pKa +7.15; +9.45) and acid- (pKa +2.5) active sites, the amount of which is determined by the composition of the samples. The high content of Lewis acid sites in the ash is associated with silicon atoms. The number of Bronsted sites depends on the horsetail treatment scheme. On the surface of samples obtained by oxidative roasting and those pretreated with water, the number of Bronsted active sites at pKa +2.5 and pKa +9.45 is higher compared to ash isolated following hydrolysis with hydrochloric acid. A comparative characteristic of the distribution curves of acid-base centres of silicon-containing ash samples obtained from the above-ground parts of field horsetail and rice straw is given, indicating their similarity.

Cement production with pozzolans from residual tropical soils formed from paragneiss with a high silicon oxide content

The manufacture of cement demands a lot of energy and gives off large amounts of CO2. Calcined clays need less energy and emit water instead of CO2, which has drawn attention to them, especially those rich in kaolinite. However, their use has been discouraged due to their location and high market price. Hence, the present study focuses on calcined clays with a low kaolinite content, specifically those derivedfrom paragneiss. In Colombia they are located in weathering horizons with depths of up to 40 meters. The results showed contents of 20%Al2O3, less than 14% Fe2O3, more than 60% SiO2, less than 40% kaolinite, 20% illite and more than 30% quartz. Calcined at 750 °C, they were used in mortars, obtaining SAI values of between 80 and 100% after 28 days, which, added to the results of Frattini tests, show that their use as a supplementary cementing material is feasible.

Research on structure of a ash-slag pulp and its influence on pipelines’ attrition of a thermal power plants’ hydraulic ash removal system

One of the key characteristics, affecting intensity of slurry pipelines’ attrition, is the abrasiveness of the transported material. It depends on the content of silicon oxides, a form and fineness of ashes particles. According to input data, it is figured out that different types and grades of coals with different chemical properties, fractional composition and coal fineness were incinerated at different times on HTPP-3. Because of it the attrition is result of different types’ transportation of ashes with various abrasive properties, with various fineness, density and chemical composition. Calculation results of pulp pipelines’ specific attrition at transportation of ash-slag pulp on HTPP-3 are given in this work.

Structural Phase State of Surface Alloyed Y2O3 Silumin After Electron beam Processing

The structure, phase composition and tribological properties of surface layers of hypoeutectic silumin after the complex processing including the electroexplosion alloying with the yttrium oxide powder in different regimes and the subsequent electron beam processing have been analyzed by the methods of modern physical material science. With respect to the initial silumin the ≈20-fold increase in the wear resistance and ≈1.5-fold decrease in the friction coefficient have been detected. The complex processing is accompanied by the formation of the multiphase submicro—nanocrystalline layer up to 80 μm in thickness enriched by yttrium and oxygen atoms responsible for the multiple increase in the wear resistance. At the complex processing according to the first regime of electroexplosion alloying (EEA) (Y2O3 powder mass—0.0589 g, discharge voltage—2.8 kV) with the subsequent electron beam irradiation, the major phase of the modified layer is the solid solution based on Al (≈71.2 mass %), the remaining phases are SiO2, YAlO3, YSi2. The 1.5-fold increase in the mass of Y2O3 powder at EEA and 1.1-fold decrease in the discharge voltage is accompanied by the increase in the quantity of phases, the significant (more than 2.5-fold) decrease in the content of the solid solution based on Al, the ≈2.2-fold increase in the content of silicon oxide, the presence of yttrium oxide and metallic yttrium.

Mechanoactivation Of Rice Husk Ash In Laboratory Conditions

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.

Operating properties of the coating, depending on the composition during plasma-chemical modification

Compositions of protective and decorative coatings on the basis of a mixture of high alumina refractory, liquid glass and dyeing salts of metals are developed. The color of the coatings depends on the type of dyeing salt and the concentration of the aqueous solution. Data on the effect of the composition on the operational properties of vitreous coatings obtained by the method of plasma-chemical modification are presented. The increased content of aluminium and silicon oxides provides an improvement in a number of characteristics such as microhardness, heat resistance, water resistance and acid resistance, which are essential in the formation of protective and decorative coating. It is established that at the rate of plasma jet passage up to 15 mm/s a protective-decorative coating with uniform texture is formed, at the rate of plasma jet passage 20 mm/s and more the coating represents a hilly surface with separate and congested deformed drops of frozen melt.

Microstructure and mechanical properties of doped and electron-beam treated surface of hypereutectic Al-11.1%Si alloy

The effect of electroexplosive doping in two modes with subsequent intense pulsed electron beam treatment of hypereutectic Al-11.1%Si alloy (silumin) on the change of its structure and phase composition, mechanical and tribological properties has been investigated. Methods of methods of scanning electron microscopy, electron microprobe and X-ray diffraction analysis were used to analyze changes of the structure, phase composition, and morphology of the modified surface of hypoeutectic silumin subjected to a complex treatment. Change of tribological and mechanical properties after the complex energy deposition is evaluated: the microhardness increases by 3.2 times (2.34GPa in contrast to 0.73GPa in the as-cast state), the wear parameter (inverse to the wear resistance) decreases by 18–20 times (from 49⋅10−4mm3/N⋅m to 2.5⋅10−4mm3/N⋅m) and the friction coefficient decreases by ≈1.5 times (from 0.55 to 0.36). It is revealed that a complex treatment mode hardly affects the studied properties but it has a strong effect on the phase composition of a modified layer (the content of the aluminum-based solid solution is reduced by 2.5 times, and the relative content of silicon oxide grows by ≈2.2 times). The multiphase submicro- and nanocrystalline structure formed in the surface layer is responsible for changes in the wear resistance and microhardness, and special features of the thermal action by an intense pulsed electron beam on the surface govern a decrease in the friction coefficient.

Agricultural Waste as a Reinforcement Particulate for Aluminum Metal Matrix Composite (AMMCs): A Review

The desire to create sustainable development through research birthed this study. Over time, several authors have focused on the utilization of various chemical particulates as reinforcement constituents for metallic matric composites (MMCs) and aluminum metal matrix composites (AMMCs), which has thus far yielded positive outcomes for achieving the chemical, mechanical, microstructural, thermal, corrosion, and wear property improvement of various reinforced composites. However, this study focused on the search for the residing potentials in alternative materials that can be used as reinforcement particulates in place of the commonly used graphite, silicon nitride, titanium nitride, zirconium, and the likes. This study literarily revealed, via several reviews of literature, that the search for less expensive and easily procured materials with a silicon oxide and magnesium oxide chemical content instigated the utilization of materials from agricultural waste (agro-waste). According to the reviewed literature, some of the waste materials from agriculture that have been found to be useful for the particulate reinforcement of composites are groundnut shell, coconut shell, rice husk, breadfruit seed hull ash, aloe vera, bean pod ash, cow horn, and so on. It was discovered that processed agro-wastes in the form of powdery particulates have demonstrated great reinforcing abilities, as recorded in literature. In addition, they enhanced the mechanical properties of the various composites developed in comparison to the as-cast materials.

Plasma coatings containing high-baring phases

Results of comparative researches of the initial and processed in a plasma flow oxidic microcomposites, consisting of TiO2, SiO2, Al2O3, ZrO2, and plasma coverings from them – the materials which are characterized by amorphous and crystal structure and strengthened by ultradispersed phases of the stishovit, are presented. It is shown the influence of a type, structure and a way of processing of material (initial powder of different dispersion; the powder obtained in a plasma flow at the different modes and with the normal and accelerated cooling; a plasma layered composite) on the content of silicon oxides, aluminum and titanium, on the type of polymorphic transformations (anatase is found both in powders, and in coverings; the accelerated cooling of spheroids leads to growth of its contents in microcomposites) and also on feature of forming in ceramic materials of a high-bar phase – the stishovit (stishovit it is found only in coverings). It is established that increase in power of the plasma generator leads to increase in extent of amorphicity of plasma-layered composites. In the structure of layered composites three groups of the inclusions, combined by the composition, are revealed: two groups of aluminosilicates and inclusions on the basis of zirconium dioxide. Inclusions of the third group are characterized by two types of structures: homogeneous, consisting of zircon, and plated (with a kernel of dioxide of zirconium and a cover from zircon). The developed layered composites are characterized by high wear resistance, corrosion resistance and antifriction properties. In the conditions of low-temperature plasma at atmospheric pressure the stishovit-containing materials are obtained for the first time.

Preparation of silicon oxide–carbon composite from benzene and trimethoxyphenylsilane by a liquid phase plasma method for supercapacitor applications

Silicon oxide–carbon composites (SiOCCs) were deposited directly in a reactant aqueous solution using a liquid-phase plasma (LPP) method and applied as a supercapacitor electrode. The SiOCCs formed rapidly at the initial stages of the LPP reaction by the carbonization of benzene and TMPS, but the production of SiOCC decreased over the reaction time. The SiOCCs formed cluster chains by agglomeration, which were composed mostly of carbon with oxygen and silicon distributed uniformly. A higher TMPS content in the reactant solution resulted in the inclusion of more silicon and oxygen in SiOCCs. Most of the Si components synthesized by the LPP reaction form SiO2 bonds and some have carbon-bonded chemical structures. The SiOCCs particles were agglomerated in amorphous form with a size of approximately 10 to 40 nm and the d-spacing appeared to contain SiO2 particles of approximately 0.31 nm. As the content of silicon oxide in SiOCCs is increased, the specific surface area increased and the specific capacitance increased. In addition, the pseudocapacitance characteristics showed the lowest resistance. On the other hand, a higher silicon oxide content in SiOCCs resulted in higher capacitance loss due to volume expansion of silicon dioxide in the charge-discharge process.

PHYSICO-CHEMICAL PROPERTIES OF A NEW CLAY-BASED SORBENT

The main physical and chemical parameters of a new sorbent developed on the basis of the minerals of the Samara region: clays, peat and dolomite are considered. The particle size of the clay after grinding at the stage of preliminary preparation was less than 1 nm, which relates them to highly dispersed materials. A chemical analysis of the composition of the components showed a high content of silicon and aluminum oxides, which possess ion exchange properties, and also made it possible to assign clays to montmorillonite rocks. The modification of the sorbent was carried out by thermal method. The density of the finished sample was 1.8 g / cm3. The method of scanning electron microscopy showed that the structure of the finished sample belongs to spongy bodies. The method of IR spectrometry confirmed the presence of functional groups in the crystal lattice of the sorbent, which cause not only the physical, but also the ion exchange and chemical nature of sorption.

Processing of mineral part of refined ferrochrome slags to obtain pelleted porous heat insulator

In the wastes of the joint stock Aktobe Ferro-alloy plant, there are over 12 mln ton of refined ferrochrome slags that contain significant amounts of the metal dorebead. Dust-like mineral part of the slagof refined ferrochrome mainly consists of di-calcium silicate contaminated with poisonous compounds of hexatomic chrome. The metal can be separated from the mineral part by air separation and screen sizing, while the mineral part of the slag can be very efficiently mixed with Kazakhstani ferri-ferrous diatomite(opoka) and fluid glass and thermally processed to obtainglass-like heat insulating material. Being heated up to t ≥ 1000оС Di-calcium silicate interacts with finely divided ferrumdioxyde and hydrated silica to formporous glass phase of ferro-silica-calcium compounds that strengthen the heat-processed pellets against any mechanical influence. It was found that the optimum conditions for pellet production are: the ratio of diatomite ore to the mineral part of the RFX slag 2: 1, because at other ratios, the formation of a rolling glass-phase pellet is observed, the processing temperature is 1050 ° C, because at lower temperatures there is practically no formation of a glass phase. The compounds of hexatomic chrome het destroyed at heating and dissolve in the glass mass where they become insoluble. It is shown that the mineral part of RFX slags due to the relatively high content of calcium and silicon oxides is a valuable raw material for the production of granular porous heat-insulating material. The proposed technology makes it possible to extract a high-value metal component of RFX slags in the form of an expensive metal concentrate of refined ferrochromium and to obtain porous pellet fillers for reinforced concrete products.

SILICA AND IRON OXIDE EXTRACTION FROM ALUMINA-CONTAINING SWEEPINGS OF ALUMINUM PRODUCTION

The paper suggests a method for recovering contaminants from aluminum-production waste called sweepings to return them further to the electrolytic cell. It is proposed to use the grinding – sizing – reverse flotation – thickening scheme for material beneficiation. Flotigam 7266 (Clariant, Germany), a mixture of primary fatty alkylamines, was used as a flotation reagent in the study to completely remove silicon and iron oxides. The combination of pine oil mixed with kerosene was used to remove carbon particles. Flotation was conducted on the FML 0,3 flotation machine. The raw material, chamber product and tailings were analyzed for the content of carbon and aluminum, iron and silicon oxides using X-ray diffraction, X-ray phase and chemical analysis. It was found that processing the overall mass of the material does not provide a product with an acceptable content of silicon and iron oxides. Based on the X-ray phase analysis of various raw material fractions it was proposed to process material fractions containing minimum contaminants (carbon, silicon and iron oxides). Two fractions were chosen for flotation processing: –0,071 mm and +5,0 mm according to the X-ray diffraction analysis of various material fractions. Processing the first fraction allowed obtaining the chamber product of an acceptable quality. The coarse electrolyte-containing fraction (+5,0 mm) provided the product with the high content of alumina and fluorinated components and low content of carbon and iron oxide, but with a significant amount of silicon oxide. Further use of this product is possible to obtain silicon-aluminum alloys.