Search results

Studies on the surface modification of sodium‐aluminium silicate P‐820 using silane coupling agents are described. The best modifiers were selected, which induced a change of the silicate surface from hydrophilic to hydrophobic. Physicochemical analyses of the modified silicate were performed. The methods of evaluating silicate surface modification degree were presented. The degree of hydrophobization of silicate surface was determined by a calorimetric method. Near infra‐red spectroscopy (NIR) was used to determine the degree of condensation of the silicate surface silanol groups. Studies on morphology and microstructure using transmission electron microscopy (TEM) were performed. Attempts were made to apply the unmodified and modified sodium‐aluminium silicate P‐820 as filler and pigment in silicate and dispersion paints.

The study reported here concerned production of green pigments, hydrated nickel(II) silicates and oxides, obtained by precipitation from solutions of sodium metasilicate and sodium hydroxide using nickel(II) sulphate.

The pigments were analysed using a number of techniques including scanning electron microscopy for particle surface morphology and dynamic light scattering for particle structure and the tendency of the particles to agglomerate.

The most desirable physicochemical parameters were shown by highly dispersed nickel(II) silicates precipitated in presence of the modifying agents. Silicate pigments precipitated in the presence of Rokanol K‐7 had low bulk densities, a high capacity to absorb water, dibutyl phthalate and paraffin oil within the primary particles, which is particularly noteworthy.

Due to their good dispersibility, well developed surface and appropriate coating power, coloured silicates of, e.g. chromium(III) and nickel(II) may be used as pigments and fillers for surface coatings.

The method of obtaining nickel(II) pigments developed was novel and provided a solution for problem of post‐galvanic nickel solutions.

To identify a method of evaluation as well as conditions under which corrosion in the form of flash rusting attacks steel treated with a coating of water‐borne binders.

The paper worked with soluble alkaline silicates – sodium silicate – acting as flash rusting inhibitors, while aqueous dispersion binders were used in primer paints. Sodium silicate, potassium silicate and lithium silicate were studied from this point of view. Their inhibiting properties were described with the aid of a scanning method, determination of metal weight loss and electron raster microscopy.

Sodium silicate was identified as a very good flash rusting inhibitor for applications in styrene‐acrylate water‐borne paints.

Sodium silicate, potassium silicate and lithium silicate can be used in industrial coatings as high‐performance inhibitors of flash rusting.

A coating containing corrosion defects occurring during the creation of a film loses its anticorrosion properties and provides only low anticorrosion protection against atmospheric corrosion when the film of coating is later exposed to a corrosion environment. This paper proved that silicates could be very efficient flash rusting inhibitors under certain conditions.

Presents the outcome of intensive research into highly dispersed sodium‐aluminium silicate. Optimal conditions of the precipitation process of sodium‐aluminium silicates of high dispersion degrees from the solution of sodium metasilicate were given. In the precipitation process water soluble aluminium salts were used. A physicochemical analysis and microscopic structure of the obtained silicates were performed. The products obtained are characterized by parameters comparable to those of the sodium‐aluminium silicate P‐820 (Degussa).

This study examines the effects of using magnesium chloride as a precipitating agent of sodium silicate on the mechanical, optical and fire retardant properties of the resulting paper sheets. Two types of treatments (internal and external), were carried out to investigate such effects on the paper sheets prepared from wood pulp and from non‐wood fibrous, bagasse pulp. The results obtained showed that the treatment of paper sheets with either sodium silicate or sodium silicate‐magnesium chloride led to a decrease in the activation energy of the initial main degradation stages. Wood pulp‐paper sheets treated with sodium silicate showed better fire retardant properties than the sodium silicate‐magnesium chloride treated wood pulp‐paper sheets. A reverse trend was noted in the case of paper sheets made from bagasse pulp.

An attempt was made to precipitate highly dispersed carbonate‐silicate fillers from solutions of metasilicate sodium and calcium hydroxide using gaseous carbon dioxide. Optimum conditions were defined for precipitating these powders. Carbonate‐silicate fillers were subjected to surface modification employing two techniques: the wet one, applied in the course of precipitation, and the dry one. For the modification, silane coupling agents were used. The carbonate‐silicate fillers were subjected to physicochemical analysis. Moreover, particle size distribution was determined using the DLS technique and their surface morphology was examined using SEM. The modified carbonate‐silicate filler was applied as a substitute of titanium white and a filler in acrylic paints.i

Tungstate inhibitors are seldom used alone in open recirculating cooling water systems due to their low oxidising ability and high cost. The objective of the present work was to develop efficient synergistic inhibitor combinations comprising sodium silicate and very low concentration of sodium tungstate, keeping in view of their application in industrial cooling water system. It was demonstrated in the present study that all the combinations of the inhibitors exhibited synergistic benefit and higher inhibition efficiencies than did either of the individual inhibitors. It was also established that a 4:1 ratio of sodium silicate to sodium tungstate (total 1,000 ppm) was the best overall combination. The FTIR spectra also suggest that tungstate and silicate ions were incorporated in the passivating metal oxide layer formed on the surface of carbon steel in the inhibitor solutions. The effects of excess and depleted concentrations of the individual inhibitor components on overall inhibition behaviour are also discussed.

Potassium silicate sealer was applied on solvent-cleaned, acid-pickled, dacromet-coated steel to improve its corrosion resistance. The purpose of this paper is to study the corrosion behavior of dacromet-coated steel.

Potassium silicate sealer was applied on solvent-cleaned, acid-pickled, dacromet-coated steel to improve its corrosion resistance. Electrochemical impedance spectroscopy (EIS), potentiodynamic polarization, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and salt spray were carried out. SEM was used to study the morphological appearance of the surface.

The EIS behavior indicated that solvent-cleaned dacromet-coated steel sealed with potassium silicate showed that the corrosion current density was 2.664E − 5 A.cm² which was reduced to 8.752E − 6 A.cm² and the corrosion rate, which was 2.264E − 2 mm.year⁻¹, was reduced to 7.438E − 3 mm.year⁻¹ in NaCl 3.5 wt.per cent. EIS was used in NaCl 3.5 wt.%, and the Bode plot characteristics showed that the corrosion protection of solvent-cleaned, dacromet-coated steel was enhanced when sealed with potassium silicate. The EDS results of salt-sprayed, solvent-cleaned samples after 10 days indicated that the main corrosion products are composed of SiO₂, ZnO and Al₂O₃.

The detection of Li element in EDS was not possible because of the device limitation.

The current paper provides new information about the sealing properties of potassium silicate and its effects on the corrosion resistance of dacromet coating, which is widely used in many industries such as the automobile industry.

The purpose of this paper is to investigate epoxysilane‐modified silica sols as surfactant‐free inorganic pigments dispersants and as co‐binders/reinforcing agents for silicate paints.

The performance of epoxysilane‐modified silica sols as dispersants for titania was studied using a polyacrylate‐based dispersant as reference. Furthermore, the effect of the addition of silica sols, with or without silane modification, to potassium silicate on binder properties was investigated.

Significant improvements were obtained in stability towards settling in water‐based titania pigments pastes and in light‐scattering efficiency (as much as 50 per cent) for the optimal size of the silica particle of 5 nm. The number of silane molecules per nm² silica particle surface must exceed a critical value of at least 1 molecule of epoxysilane per nm² particle surface. Additionally, improved stability towards gelling, water resistance and film‐forming properties of sol‐silicate binder mixes were achieved for epoxysilane‐modified silica sols.

Only epoxysilane‐modified silica sols were studied in this report. Titania pigment was examined but other important pigments (e.g. iron oxides) remain to be studied. In addition, only sol‐silicate mixes were investigated and not fully formulated silicate paints.

A method that produces stable, high‐performing, surfactant‐free inorganic pigments pastes. Furthermore, stable, high‐ratio, sol‐silicate binders can be obtained with improved water resistance and film properties for use in silicate paints.

The present method provides an easy route to obtain stable surfactant‐free inorganic pigments pastes, as well as makes stable, high‐ratio, sol‐silicate mixes/paints.

To study and compare the inhibition effects of eco‐friendly inhibitors of sodium silicate and 1‐hydroxyethylidene 1,1 diphosphonic acid (HEDP) in corrosion control and prevention of soft water discolouration (red water) in carbon steel pipelines.

Electrochemical impedance and Tafel polarization measurements were used to study corrosion inhibition properties. The experiments were carried out under different concentration ratios of inhibitors. Different hydrodynamic conditions were applied to simulate pipeline fluid flow. Scanning electron microscopy (SEM) and EDAX analysis were used for surface studies.

It was observed that corrosion inhibitor combinations under static conditions showed synergistic effects at low concentrations. The inhibition efficiency and synergistic behaviours of inhibitors were enhanced as the electrolyte turbulence was increased. In addition, the inhibitor concentration value required to reach maximum inhibition decreased. It was found that at 20 ppm sodium silicate and 5 ppm HEDP, co‐inhibition efficiencies increased significantly to more than 90 per cent and the corrosion rate decreased far below 1 mpy as the electrode rotational speed was increased. Surface studies using SEM revealed the formation of a compact and uniform film of co‐inhibitors.

The results of this paper can be used for the development of effective, non‐toxic and economically attractive corrosion inhibitor formulations for soft water transmission pipelines.

The observed synergistic behaviour can be due to the incorporation of the silicate gel‐like network through organic phosphorous bonds. The hydrodynamic condition of the electrolyte leads to enhancement of inhibition efficiency, which indicates that the corrosion inhibition was mass transfer controlled.