RU2352544C1 - Method for production of highly porous cellular glass-ceramic material - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: invention may be used in chemical industry for production of catalyst carriers and thermal protection elements, in mass exchange processes, etc. Method for production of highly porous cellular glass-ceramic material includes impregnation of polymer matrix (polyurethane foam) with slurry solution, which consists of dispersed phase and dispersed medium with further drying and application of sol on produced stock with further drying and high temperature treatment. At that slurry used is finely crushed glass that contains the following components, wt % SiO₂ - 53-70; CaO - 10.3-18.8; MgO - 19.2-28.8; and also over 100%: Na₂O - 5.0-7.0; Fe₂O₃ - 5.0-7.0; Al₂O₃ -6.0-8.0; Cr₂O₃ - 0.7-1.5 and 5-7% aqueous solution of polyvinyl alcohol, in ratio of 70:30 (wt % glass powder : PVA). High temperature treatment of polyurethane foam matrix impregnated with slurry includes stages of sintering and crystallisation at the temperature of 800-830°C with delay time of 1.5-3 hours.

EFFECT: production of highly porous cellular glass-ceramic material of required shape, lower power inputs and cost reduction of initial raw stock.

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Description

The present invention relates to the field of chemical technology of highly porous materials with a mesh-cellular structure, in particular to a method for producing a highly porous cellular glass-crystalline material, and can be used in the chemical industry for the manufacture of catalyst supports and thermal protection elements, in mass transfer processes, etc.

Recently, highly porous cellular materials based on various types of ceramics and metals have gained increasing popularity among macroporous materials. Such materials are used for filtering hot air currents and molten metals, the manufacture of catalyst carriers and thermal protection elements, in mass transfer processes, etc. Such materials are characterized by a developed specific surface area and a low apparent density (VV Antsiferov. Use of highly porous cellular materials. / V.N. Antsiferov, M.Yu. Kalashnikov // Ecology and industry of Russia. - 1997. - No. II. - C .14-17).

A known method of producing inorganic porous materials based on glass and glass ceramics by sol-gel transition, having interconnected continuous macropores with an average diameter of more than 0.1 mm and having mesopores on the walls of these macropores with an average diameter of 2-100 nm. This method involves dissolving a water-soluble polymer or other pore-forming agent and a starting material for an agent that dissolves the matrix in a medium that promotes the hydrolysis of organometallic compounds. Mixing an organometallic compound that contains hydrolyzable ligands in a medium conducive to a hydrolysis reaction. The hardening of the mixture occurs through a sol-gel transition, in which a gel is formed having three-dimensional interacting phase regions, one of which is rich in solvent, and the other is an inorganic component containing surface pores. Then, the curing agent dissolving the matrix does not contain the starting material. In this case, the matrix dissolving agent changes the structure of the inorganic component. Then drying and / or heat treatment takes place and finally the gel is fired to form a porous material.

Silica (SiO ₂ ) is used as the inorganic component, and urea matrix (urea) or any other compound containing an amide or alkylamide group is used as the starting material, agent.

As a pore-forming agent, neutral surfactants are used (US Pat. US 6207098 B, class 264/414 of 03/27/2001).

However, this method does not allow to obtain cellular glass-crystalline materials with a characteristic pore (cell) size of from 0.5 to 4 mm.

The closest in technical essence and the achieved result is a method for producing highly porous ceramic products with a mesh-cellular structure by impregnation of a polymer matrix (polyurethane) with a slip consisting of a dispersed phase and a dispersion medium, followed by drying and applying to the resulting workpiece an aluminosol or aluminum chloride without or with the introduction of active additives at pH 4 + 2. Then the products are dried and fired at a temperature of 1450-1500 ° C (US Pat. RF No. 2294317, CL 38B 38/00 from 03/15/07).

However, this method requires high costs for raw materials and electricity.

The objective of the invention is to provide the possibility of obtaining highly porous cellular glass crystalline material of the required form, reducing energy consumption for obtaining the product and cheapening the feedstock.

The problem is solved by the method of obtaining a highly porous cellular glass crystal material by impregnating a polymer matrix consisting of polyurethane foam, a slip solution consisting of a dispersed phase and a dispersion medium, followed by drying and applying a sol to the resulting billet with further drying and high-temperature processing, and use as a slip glass crushed in a ball mill to a dispersed state of less than 10 microns, with the ratio grinding body: glass: H ₂ O (dist.) = (2-3) :( 1-1.3) :( 2.5-3), Acquiring by cooking the mixture components consisting of SiO _2, CaCO _3, MgO, Na ₂ CO _3, Al ₂ O _3, Fe ₂ O _3, Cr ₂ O ₃ to form a dispersed phase consisting of glass comprising the following components in wt. %:

SiO ₂ - 53-70;

CaO - 10.3-18.8;

MgO - 19.2-28.8;

and also in excess of 100%:

Na ₂ O - 5.0-7.0;

Fe ₂ O ₃ - 5.0-7.0;

Al ₂ O ₃ - 6.0-8.0;

Cr ₂ O ₃ - 0.7-1.5

and a 5-7% aqueous solution of polyvinyl alcohol in the ratio of 70:30 (wt.% glass powder: PVA), and high-temperature treatment of slip-impregnated polyurethane foam organic matrix includes sintering and crystallization stages at a temperature of 800-830 ° C with a holding time of 1.5 -3 hours.

Example 1

The raw material base for producing a cellular glass-crystalline material consists of glass, the crystallization of which takes place in the pyroxene region. After mixing the raw materials in a gas furnace, glass is boiled at a temperature of 1480 ° C. The composition of the obtained glass SiO ₂ = 70.0 wt.%, Na ₂ O = 7.0 wt.%, CaO = 10.3 wt.%, MgO = 19.7 wt.%, Al ₂ O ₃ = 7.0 wt.%, Fe ₂ O ₃ = 5.0 wt.%, Cr ₂ O ₃ 0.7 wt.%. Oxides Na ₂ O, Al ₂ O ₃ , Fe ₂ O ₃ , Cr ₂ O ₃ are introduced into the glass composition in excess of 100%. After cooking, the resulting glass was crushed in a ball mill to a dispersed state of less than 10 μm, with a ratio of grinding body: glass: H ₂ O (dist.) = 2.0: 1: 2.5. The ground glass was mixed with a 5% aqueous solution of polyvinyl alcohol (PVA) in a ratio of 70:30 (wt.% Powder of glass: PVA) until a stable slip suspension was formed. Billets of polyurethane foam (PNU) with a mesh size of 1.5-4.0 mm were impregnated with the obtained slip. The excess slip was squeezed. The billet was dried in a muffle furnace at a temperature of 100 ° C for 80 min. Next, the preform was immersed in a sol of silicic acid and again dried in an oven at a temperature of 150 ° C for 1.5 hours. The high-temperature processing of the samples obtained after the last drying was carried out in a furnace with silicon carbide electrodes at 810 ° C for 3 hours to pass the crystallization process. In the process of crystallization, pyroxene solid solutions based on diopside are released. The resulting material has an apparent density of 0.28 g / cm ³ , porosity of 90%, compressive strength of 0.6 MPa, volumetric shrinkage of 8%, mesh size of 1.0-3.5 mm, weight loss when boiling in conc. HCl - 1.2%.

Example 2:

After mixing the raw materials, glass is boiled at a temperature of 1500 ° C. The composition of the obtained glass SiO ₂ = 60.0 wt.%, CaO = 11.8 wt.%, MgO = 28.2 wt.%, Na ₂ O = 5.0 wt.%, Al ₂ O ₃ = 8.0 wt.%, Fe ₂ O ₃ = 7.0 wt.%, Cr ₂ O ₃ 1.2 wt.%. Oxides Na ₂ O, Al ₂ O ₃ , Fe ₂ O ₃ , Cr ₂ O ₃ are introduced into the glass composition in excess of 100%. After cooking, the resulting glass was crushed in a ball mill to a dispersed state of less than 10 microns, with a ratio of grinding body: glass: H ₂ O (dist.) = 3.0: 1.3: 3.0.

The ground glass was mixed with a 7% aqueous solution of PVA in a ratio of 70:30 wt.% (Glass powder: PVA) until a stable slip suspension was formed. Preforms of polyurethane foam with a size of 0.5-2.5 mm were impregnated with the obtained slip. Further, everything is as in example 1. High-temperature processing was carried out at a temperature of 830 ° C with a shutter speed of 1.5 hours. In the process of crystallization, pyroxene solid solutions based on diopside are released. Technical characteristics of the obtained highly porous glass crystal material:

Apparent density 0.35 g / cm ³ Porosity  84% Compressive strength  0.9 MPa Volumetric shrinkage  4.0% Sintered specimen cell size  0.5-2.0 mm Weight loss on boiling at conc. Hcl  0.8%

As can be seen from the examples, the obtained highly porous cellular glass crystal material has high physicochemical properties. An analysis of the results shows the possibility of obtaining highly porous cellular materials from glass by crystallization according to a given temperature-time regime. Pyroxene solid solutions based on diopside are distinguished as the main crystalline phases, which impart high physicochemical properties to this material. Compared with the prototype, this method allows to obtain highly porous cellular materials with lower costs for heat treatment (lowering the maximum heat treatment temperature from 1500 ° C to 830 ° C) and for raw materials (1.5-2 times).

Claims (1)

A method for producing a highly porous cellular glass-crystalline material, comprising impregnating a polymer matrix (polyurethane foam) with a slip solution consisting of a dispersed phase and a dispersion medium based on polyvinyl alcohol, followed by drying and calcination to remove the organic component, applying a drying sol to the resulting preform, and further high-temperature processing, characterized in that as a slip, glass is used, crushed in a ball mill to a dispersed state of less than 10 microns, with the ratio of the grinding body: glass: H ₂ O _dist = (2-3) :( 1-1.3) :( 2.5-3) obtained by cooking the components of the mixture at a temperature of 1450-1500 ° C to obtain a dispersed phase consisting of glass, including the following components, wt.%:
SiO ₂ 53-70 CaO 10.3-18.8 MgO 19.2-28.8
and also in excess of 100%:
Na ₂ O 5.0-7.0 Fe ₂ O ₃ 5.0-7.0 Al ₂ O ₃ 6.0-8.0 Cr ₂ O ₃ 0.7-1.5
and a 5-7% aqueous solution of polyvinyl alcohol in the ratio of 70:30 (wt.% glass powder: PVA), and the high-temperature treatment of slip-impregnated polyurethane foam matrix includes sintering and crystallization stages at a temperature of 800-830 ° C with a holding time of 1, 5-3 hours