Polysilicate Solutions Research Articles

Formation of ceramic coating on VAL10 aluminum alloy surface via laser modification in polysilicate solution

This article presents the results of an experimental study on the physical and mechanical properties of the surface layer of the VAL10 aluminum alloy after pulsed laser treatment, conducted in a bath with an aqueous solution of polysilicates (PS) at various concentrations. Ceramic coatings were produced on specimens measuring 10×10×3 mm. The laser processing of aluminum alloy specimens was carried out using an Nd:YAG laser. The study demonstrates that the quality of the resulting surface and its properties can vary depending on the laser exposure parameters, the concentration of the polysilicate solution, and the overall processing technique. The scattering of radiation by the PS solution layer leads to a significant reduction in surface roughness. In specimens processed in ambient air, the crater sizes on the surface exceeded 400 μm, while for specimens processed in a PS solution, they did not exceed 100 μm. A comparative analysis of the impact of solution concentration on elemental composition was performed. The study also included an investigation of friction characteristics and the measurement of microhardness of the modified surface. The research revealed that surface hardening processes occur as a result of the treatment, associated with the filling of recesses with high-strength oxides. This enabled the creation of a mixture containing silicon carbide and aluminum oxide in the surface layer of the specimens. Furthermore, wear tests of the modified surface were conducted using a “ball–specimen” tribological coupling. Specimens subjected to laser irradiation in a PS solution demonstrated increased wear resistance (a 40 % reduction in wear) and a 30 % decrease in the friction coefficient. Additionally, an increase in microhardness was observed.

Generation of Multifunctional Oxide Coatings on Surface of Val10 Alloy in a Polysilicate Solution

Experiments on the effective deposition of an oxide-ceramic coating on cast aluminum alloy VAL10 have been carried out, alloowing quick application of hardening coatings that minimize main disadvantages of aluminum alloys, such as low strength and surface hardness. Protective coatings were applied using a LIS-25 laser device with a laser radiation wavelength of 1.06 μm. The substrates had dimensions of 10x10x3 mm. Laser treatment of the samples was carried out in a solution of polysilicate Na2SiO3 of various concentrations. Empirically, the optimal concentration of the solution was clarified. The chemical composition of the prepared sample surface was studied by Auger electron spectroscopy. A JAMP-10 S setup (JEOL, Japan) was used as an Auger microanalyzer. A control sample with treated in air surface was made for comparison. The composition of the coating obtained in a solution of polysilicate, in addition to aluminum, includes: carbon, calcium, oxygen, sodium, silicon. In the form of Auger lines, aluminum is in an oxidized state, and carbon and silicon are in the form of carbide. The coating obtained in a polysilicate solution has significant differences from the coating obtained in air. The coating obtained in a polysilicate solution has a more uniform structure, less roughness, and there are no characteristic craters from laser radiation exposure.

Compositions for Limestone Restoration

Information about the lime composition used for the restoration of limestone is given. To develop a repair composition, a polysilicate solution was used. It has been established that polysilicate solutions contain a monomer, oligomer and polymeric varieties of silica. It was found by the molybdate method that the content of the polymeric form of silica γ-SiO2 in the polysilicate solution is 15–19.93%, depending on the content of the silica sol. This composition of the polysilicate solution contributes to the manifestation of the high reactivity of silica. The technology for carrying out restoration work involves the application of a primer layer - liquid glass, followed by the application of a calcium chloride solution. After 20-30 minutes after applying the primer, it is possible to apply the repair composition with a spatula. It is shown that the use of a polysilicate solution in the formulation of a lime composition helps to increase the water resistance, adhesion strength of the composition to the base, and accelerates curing.

Lime compounds for restoration and decoration of building walls

Information on the effect of a polysilicate solution obtained by mixing liquid glass with a silicic acid sol on the structure formation of lime compositions is presented. It was revealed that the amount of specific heat released when lime is wetted with a polysilicate solution is greater than when lime is wetted with water. This is due to the additionally released heat due to the chemical interaction of lime with polysilicate solution. It was found that the introduction of a polysilicate solution accelerates the development of plastic strength. For comparison, we used liquid glass and a sol of silicic acid as an additive. The synergistic effect of the influence of the polysilicate solution on the structure formation of lime finishing compositions was established, which manifests itself in the acceleration of the set plastic strength in comparison with silica sol and water glass. It has been established that the introduction of a polysilicate solution into the lime mixture formulation contributes to an increase in the resistance to slipping of the finishing layer. The optimal thickness of the finishing layer was determined, which is 20 mm, at which sliding from the vertical surface is not observed.

Assessment of the Structure of Polysilicate Binding with Added Glycerol

The article presents the results of the study of the properties of the sol of silicate paint. The chemical structure of the polysilicate solutions obtained with the addition of glycerol was studied by IR spectroscopy. It is shown, that the interaction of potassium liquid glass and glycerol is weak and due to the partial replacement of hydrogen ions by potassium ions.

Natural fiber reinforced inorganic foam composites from short hemp bast fibers obtained by mechanical decortation of unretted stems from the wastes of hemp cultivations

The wettability of hemp fibers, to be applied in fiber-reinforced foams, can be improved with several chemical treatments. In this paper, a innovative treatment with sodium ascorbate was evaluated. Untreated and treated fibers have been characterized using FTIR spectroscopy and TGA measurements. Furthermore, the feasibility of treated fibers was evaluated preparing diatomite-based fiber-reinforced foams. These materials were finally characterized by mechanical compressive strength and thermal properties (thermal conductivity). The fiber-reinforced foams have been produced using a diatomite natural source as a matrix. A suitable amount of Si powder and vegetable surfactant were used as chemical and physical foaming agents while a polysilicate solution was used as reactive crosslinker. The foams highlight low density, around 350 kg/m3, and low thermal conductivity (0.06 W/mK).

Assessment of Fire Safety of Coatings Based on Silicate Paint Sol

The results of the study the fire safety of coatings, based on silicate and sol silicate paints, are presented. The rapid method of the fire tube (based on the definitions of the duration of self-combustion or smoldering and on the mass loss of the sample after exposure to an open flame) established that the coatings belong to the group of non-flammable material, for coatings, based on poly-silicate solutions, have a lower loss of mass, in comparison with coatings based on liquid glass. At the flammability test on the TPR it was established, that coating based on potassium liquid glass and potassium poly-silicate solution did not ignite seen, even at a temperature of 760 degrees. There is no smoke emission. However, a change in the shape and color was recorded. The weight loss of the sample of the coating, based on potassium liquid glass, was 30.14% by weight, and the coating sample, based on the potassium poly-silicate solution, was 27.14%. The evidence of improvement of fire hazard characteristics of coatings based on poly-silicate solutions is obtained.

Regularities of formation of adhesive contact “sol-silicate paint - substrate”

Introduction. The use as a binder in the manufacture of silicate paints polysilicate solutions obtained by mixing liquid glass and silica sol is considered. To regulate the rheological properties of the paint, improve the filling and prevent the pigment part from sagging, it has been proposed to introduce glycerin into the binder composition. The results of studying the interfacial interaction between the paint and the substrate are given. Materials and methods. In developing the formulation of silicate paints based on polysilicate solutions, MK-2 microcalcite, marshalite, diatomite and talc of MT-GSM grade were used as a filler, and titanium dioxide as a pigment. Polysilicate solutions were obtained by reacting stabilized solutions of colloidal silica (sols) with aqueous solutions of alkali silicates (liquid glasses). Nanosil 20 and Nanosil 30 silicic acid sol were used, produced by the Promsteklocentr PC. Used potassium liquid glass with module M = 3.29. A thermodynamic method was used to assess the interfacial interaction. Results. Shown that the introduction of glycerol into the formulation of a sol of silicate paint promotes a decrease in the interfacial surface tension and a better wetting of the surface of the mortar substrate. An increase in wetting coefficient is observed. Coatings based on sol silicate paints with the addition of glycerin are characterized by increased crack resistance. An increase in tensile strength, maximum tensile properties, and decrease in the elastic modulus of paint membranes based on the composition with glycerol has been established. The values of the free surface energy of the coating based on the sol of silicate paint and the ratio of the polar to the dispersion component of the free energy of the surface are given. Coatings based on sol of silicate paint with the addition of glycerin are characterized by a large value of the free energy of the surface. In the process of moistening a decrease in the free surface energy is observed due to a decrease in the dispersion component. Conclusions. Studies have shown that the introduction of an additive of glycerin in the formulation of a silicate paint sol contributes to an increase in the performance properties of coatings based on it.

POLYSILICATE BINDER FOR SILICATE PAINTS

Information is given on the structure and properties of a polysilicate binder obtained by mixing a silicic acid sol with a liquid glass. It was found that the introduction of a silicic acid sol in a liquid glass promotes an increase in the fraction of high-polymer fractions of silicic anions. An increase in the sol content promotes an increase in the fraction of high-polymer fractions of silicic anions. The results of the kinetics of the change in the silica content in the monomeric form in the potassium and sodium polysilicate solution are given. It was found that the dependence of the silica content in the monomeric form in the early stages of the interaction of the silicic acid sol with liquid glass is extremely extreme. It has been shown that when the potassium liquid glass is mixed with silica sol, the formation of silica in the monomeric form proceeds more slowly at the initial stage than in the sodium liquid glass. The results of studying the structure of polysilicate solutions by the method of violation of total internal reflection are presented. IR-spectroscopy revealed a shift in the band corresponding to Si-O-Si vibrations to the region of higher frequencies compared to liquid glass, which indicates a higher degree of polymerization of silica. The presence of silica in the polysilicate binder polymeric species is established, which ensures an increase in the stability of silicate coatings. Information on the properties of silicate composition with the use of polysilicate film-forming and coatings based on it is given. The composition is intended for interior and exterior walls of buildings.

Research of inter-phase interaction in ZOL-silicate paints

It was suggested to use polysilicate solutions obtained by mixing liquid glass and silicic acid sol as a binder in the manufacture of sili- cate paints. Information is provided on the mechanism for increasing the operational properties of coatings based on sol silicate paint. It has been revealed that polysilicate solutions form membranes characterized by higher tensile strength due to an increase in the fraction of high-polymer fractions of silicic anions in the structure of the polysilicate binder in comparison with liquid glass. The results of a study on the interphase interaction between the pigment and the film-forming agent are given. It is shown that potassium polysilicate solutions form a smaller contact angle on the surface of the pigment (filler) and are characterized by greater work of wetting and adhesion to the filler (pigment).

Structure and Properties of the Modified Binding for Silicate Paints

Information is provided about the stability of polysilicates solutions, obtained by mixing liquid glass and silica sol. It was found, that at increases the amount of silicic acid sol added, the pH of the solutions decreases with an unchanged alkali concentration. Information on the structure of polysilicate solutions are given. It has been found, that addition of the sol (increasing the silicate module) contribute to prolonging fraction of high-polymer fractions of silicic anion. The dependence of the silica content of the monomeric form of α-SiO2in the early stages of interaction between the sol and liquid glass is extreme. The maximum content of α-SiO2 depends on the type of liquid glass and the amount of sol. It is shown, that films based on polysilicates solutions, are characterized by faster curing. The manifestation of the scale factor for coatings based on polysilicate solutions was revealed.

Properties of Polysiylate Binders for Sol-Silicate Pains

Information is provided on the composition of polysilicate solutions obtained by mixing liquid glass and silica sol. It was found that the introduction of the sol leads to an increase in the silicate module and contributes to an increase in the fraction of high-polymer fractions of the silicon-oxygen anions. The results of the kinetics of the variation of α-SiO2 and β-SiO2. It is shown, that coatings based on the polysilicate solutions are characterized by faster curing. The was found correlation between the content of high-polymer fractions of silicic anions in a polysilicate solution and the tensile strength of films. Increase in the g-SiO2 content promote increase in the tensile strength of films. The composition of sol silicate paint is developed. Coatings based on paint have a high performance property.

ИССЛЕДОВАНИЕ МЕЖФАЗНОГО ВЗАИМОДЕЙСТВИЯ В ЗОЛЬСИЛИКАТНЫХ КРАСКАХ

It is proposed to use polysilicate solutions obtained by mixing liquid glass and silicic acid sol as a binder at silicate paints manufacturing. Information is provided on the mechanism for increasing the operational properties of coatings based on silicate paint sol. It has been revealed that the polysilicate solutions form films characterized by higher tensile strength due to the increase of the share of silicic anions’ high-polymer fractions in the structure of polysilicate binder in comparison with liquid glass.
 The results of studying the interphase interaction between the pigment and the film-forming agent are presented. It is shown that potassium polysilicate solutions form a smaller contact angle on the surface of the pigment (filler) and are characterized with greater work of wetting and adhesion to the filler (pigment).

Design of sustainable porous materials based on 3D-structured silica exoskeletons, Diatomite: Chemico-physical and functional properties

3D-structured silica exoskeletons-diatomite was used as reactive inorganic ingredient, with and without metakaolin to produce sustainable multifunctional diatomite-based geopolymeric foams. Suitable amount of Silicon powder and vegetable surfactant were used as foaming agents, while polysilicate solution was used as reactive crosslinker. The resulting porous materials, characterized by hierarchical porosity ranging from macro to nano-scale, were fabricated at 40°C for 24h and characterized by means of chemical and morphological investigations, contact angle, thermal and acoustic properties and fire reaction. The presence of diatomite in the produced foams provides an increase of thermal inertia, and the thermal insulation performance firstly due to the intrinsically low thermal conductivity of diatomite and also because silicon and vegetable surfactant are able to promote the formation of a co-continuous mesoporous structure. Furthermore, the created morphological structure provides a good acoustic absorption coefficient in a wide range of frequency. Finally, due to their hydrophilicity/oleophobicity character, diatomite-based geopolymeric foams could, potentially, be proposed as oil/water separation membranes.

The Efficiency of SiO2 Based Materials in Granulated Artificial Aggregates

ABSTRACTThis paper reports on the development of a new type of low cost artificial aggregates based on granulated reactive silica (AAGS) for application in lightweight concrete. The functional principle of AAGS is based on the formation of polysilicate solutions under heat treatment (up to 80 °C) and migration of these solutions into the porous space of concrete under the thermal gradients, resulting in strengthening of inter-porous space. Developed AAGSs are based on low cost local raw materials, which may contain different amounts of amorphous silica. The activity coefficient (AC) and amorphous silica content are used to evaluate the performance of raw materials by suggested accelerated method.Silica components with different genesis are investigated and ranked according to their AC. It is found out that chemogenic and biogenic siliceous rocks with a low degree of diagenetic transformations, which are mostly represented by CT-opals (a low-temperature nanoscale modification of tridymite and crystobalite, such as diatomite, tripoli and opoka) are the most highly active raw materials for AAGS. All tested siliceous materials including natural and artificial components are divided into three groups: highly active (with AC of 51–100%), active (with AC of 21–50 %) and low-active (with AC of 5–20 %). Based on theoretical and experimental studies, the requirements for AAGS raw materials are developed.

Single-phase bone cement based on dicalcium phosphate dihydrate powder and sodium silicate solution

Bone cement, based on dicalcium phosphate dihydrate as initial powder and sodium polysilicate solution as hardening liquid, was developed. The apatite phase started to form 3–4h after the cement preparation. The kinetics of phase transformations during the hardening process was investigated, applying the energy dispersive X-ray diffraction (EDXRD) technique for real time studies. The Fourier transform infrared (FTIR) spectroscopical, scanning electron microscopy (SEM) morphological studies and compressive strength test were carried out.

The Impact of Lithium Polysilicate on the Microstructure of Sand-Lime Products

The general attributes of calcium silicate products have been investigated in several studies. In this paper, we propose to use a specific modifier i.e. lithium polysilicate solution in order to examine and improve compressive strength of sand-lime bricks. The research was examined by scanning electron microscope (SEM). The main objective was to determine the phase composition in the structure of the sand-lime products.

Formation of Concentrated Polysilicate Solutions from Stabilized Silica Sols

Regularities of dissolution of colloidal SiO2 particles in the formation of concentrated polysilicate solutions from stabilized silica sols are studied. It is shown by nephelometry, IR spectroscopy, and titration analysis that the initial structure of polysilicate solutions prepared from the sols containing compact waterless colloidal SiO2 particles is destroyed with time: particles are dissolved, and soluble silica species are accumulated. Viscosity of solutions increases with time, and gels are formed at a certain stage. In polysilicates with a large specific surface area and high particle activity, most of the silica is transferred into a solution before the gelation; dissolution slowly proceeds also at later stages. Probably, the resultant system does not contain SiO2 particles.

Mullite/SiAlON/Alumina Composites by Infiltration Processing

The formation of mullite/SiAlON/alumina composites was studied by infiltrating a SiAlON/alumina‐base composite with two different solutions, followed by thermal treatment. The base composite was prepared from a mixture of tabular Al2O3 grains, fume SiO2, and aluminum powders. The mixture was pressed into test bars and nitrided in a nitrogen‐gas (N2) atmosphere at 1480°C. The infiltrants were prehydrolyzed ethyl polysilicate solution and ethyl polysilicatealuminum nitrate solution. The composites were infiltrated under vacuum, cured at 100°C, and precalcined in air at 700°C. This infiltration process was repeated several times to produce bars that had been subjected to multiple infiltrations, then the bars were calcined in a N2 atmosphere at 1480°C to obtain mullite/SiAlON/alumina composites. The infiltration process increased the percentage of nitrogenous crystalline and mullite phases in the matrix; therefore, a decrease of the composite microporosity was observed. The infiltration increased the mechanical strength of the composites. Of the two composites, the one produced using prehydrolyzed ethyl polysilicate as the infiltrant had a higher mechanical strength, before and after being subjected to a severe thermal shock.

Spin-On Dielectrics: Good News and Bad News!

AbstractFive classes of spin-on dielectrics are discussed: polysilicates, polysiloxanes, polysilsesquioxanes, polyhydrocarbons, and polyimides. The emphasis is on the first three materials because very few polyhydrocarbon spin-on materials are available for study while spin-on polyimides sorb significant amounts of water. The polymer chemistry of the silicates, siloxanes, and silsesquioxanes is linkage through Si-O-Si-O bonds. Polyhydrocarbons are primarily linked through C-C bonds. As the name implies, polyimides are linked through (usually aromatic) imide groups. Because of their polar nature, polyimides, polysilicates, and polysiloxanes have dielectric constants >3, while the large hydrocarbon content of the remaining materials results in a dielectric constant of <3. Films of polysilicates are relatively brittle and thus are limited to a thickness <1 μm. On the other hand, films of polysilsesquioxanes, polyimides, and polyhydrocarbons can be readily deposited to a thickness >1 μm. Polysilicates have high temperature (>900°C) stability and do not react with O2; most polyhydrocarbons decompose above ˜350°C and oxidize readily; some polyimides are stable to 500°C; polysiloxanes and polysilsesquioxanes readily survive 425°C in N2. (Films of the latter two materials are converted to silicates upon heating at high temperatures in O2 or steam.) The infrared spectrum of a 425°C-cured silicate film shows the presense of Si-OH bonds and water, but after a 900°C anneal, the spectrum is almost identical to that of thermal oxide. The spectra of films of polysiloxanes or polysilsesquioxanes do not exhibit Si-OH absorption. Water retention in films is deleterious to the electrical and mechanical (swelling) properties of the dielectric and to making good aluminum-to-aluminum electrical contact through submicron vias. The water leads to a mobile charge (H+) phenomenon that is readily detected by a Triangular Voltage Sweep technique. Except for polysilicates, solutions of the other spin-on materials have reasonably long (weeks-to-months) shelf-lives. Polysilicate solutions are sols and tend to gel; the time to gelling is a function of solids content and solvent. Even though they exhibit shortcomings, polysiloxanes appear to be best suited as interlevel dielectrics in multilevel metalization schemes.