LT5426B - Frost resistance and long service life porous ceramics - Google Patents

Abstract

The invention may be used to set in wall ceramics production, designed for facade, especially operating in aggressive conditions (for example, in seaboard region). Such masonry would have small thermal conductivity coefficient and would be frost resistance and long service life. Mixture of ceramic wall production was prepared from these components: clay, sand, crashed bricks, sawdust of confiner and mill glass of windows. Samples to be shaped and burned by appropriate regime arrived ceramic body, which exploitation frost resistance are more then 300 cycles, compressive strength 13,9-19,5 Mpa, density 1502-1627 kg/m??, estimated thermal conductivity coefficient 0,37-0,42 W/mK, water absorbtion by vacuum 21,24-27,06%, reserve of pore volume 38,72-48,22%.

Description

FIELD OF THE INVENTION The present invention relates to ceramic wall products and can be applied to the production of porous ceramic articles such as bricks with increased frost resistance.

Ceramic products are usually either frost resistant or porous and have a lower thermal conductivity.

A method for obtaining frost resistant ceramics is disclosed in Palmer, T. Ceramic composition with frost resistance. of Patent GB2379658, 2003. The composition of the molding mixture is as follows: clay 60-70%, calcined ceramic scrap 9-12.5%, crushed glass 10-20%, anthracite 5-10%, sand 5-10%. When such a mixture is fired at 1100-1150 ° C, the frost resistance is up to 150 cycles, but the resulting ceramic has low water absorption up to (5%) and very high combustion temperature, which is not economical. The patent (Suslov AA, Turchenko AE, Sharov AS Ceramic Mixture for Manufacturing Building Products, No. RU2270819, 2006) discloses the following formulation composition: clay 76-81%; Sodium methylsilicon 0.1-0.2%, glass shatter 14.8-19.9% and chalk 2-4%, which gives ceramics with higher strength and frost resistance (by volumetric refrigeration method). The higher strength and frost resistance ceramics obtained are described in Lokhova NA, Ryzhkova ND, Kosykh AV, Makarova IB, Gura ZI, Nekhoda DV Raw mixture for making wall ceramic article, no. of Patent RU2269500, 2006. Such improved ceramics were obtained with the following molding composition: microsilica (ultra fine silica) 30.4-31.0%, ash 56.3-57.5%, anthracite 8.8-9 , 0%, Taiga detergent 2.7-4.3%. The composition of ceramics with higher frost resistance and strength in the patent (Lokhova NA, Maksimova SM, Murashko MN, Sashenko EV Raw mixture for making wall ceramic articles, No. 2004, 2004) is as follows: clay 49.3-50.0%, microsilica 26.5-26.9%, emulsion rich in sodium 23.1-24.2%. Another patent (Makarova IA, Lokhova NA, Kosykh AV Raw Meal and Method for Manufacturing Ceramic Products. No. RU2228309, 2004) patented the composition of the formulation as follows: Clay 83.5-94.5%, Microsilica 5-16% and Detergent "Taiga" 2.5-4.0%. The compositions of the Russian patents mentioned above have the following ceramic properties: compressive strength from 20 to 35 MPa, frost resistance, determined by volumetric refrigeration method from 25 to 50 cycles, water absorption from 16.5 to 31.1% and density from 1400 to 1790 kg / m ³ .

The patents listed above describe methods for obtaining higher frost resistance ceramics, but such articles are of relatively low porosity. In addition, frost resistance was determined by volume refrigeration, which does not reflect the true durability of ceramic articles.

Patent (Lokhova NA, Maksimova SM, Murashko MN, Sashenko EV Raw mixture for making wall ceramic articles, No. RU2232150 of 2004) describes articles containing 40-95% clay, 5-60% glass and 0, 3-0.5% sulfite yeast. After burning the semi-finished products at 950 ° C, porous ceramics with low thermal conductivity (0.42 W / mK) and density (1180 kg / m ³ ) were obtained. Patents (Kosykh AV, Lokhova NA, Makarova IA Raw Meal and Method for Manufacturing Light-Vveight Ceramics, No. RU2235698, 2004) are described as having the following composition: 75.5-83% clay, anthracite 5-7%, microsilica 10-15%, sulphate soap 22.5% and after burning the semi-finished products at 1000 ° C, effective ceramics with a density of 379-389 kg / m ³ and a thermal conductivity of 0.15 W / mK are obtained. Patente Terao S., Goto K., Hiuga H. Water permeable / water retaining ceramic block and method for manufacturing this sham. of Patent JP2005132668, 2005 describes a ceramic obtained having a density of 870 kg / m ³ and a porosity of 39%. Patente Kawai K., Kitahara Y., Minobe Y. Ceramic building material, no. of Patent JP7133169, 1995 describes a porous ceramic obtained (porosity 20-50%) having a density of 1200-1800 kg / m ³ .

However, the higher porosity (high performance) ceramics disclosed in these patents are frost resistant.

No description of the frost-resistant ceramic and porous ceramics in service has been found in the literature. Ceramics (prototype) of similar properties are disclosed in the patent: Lokhova N.A., Makarova I.A., Patramanskaja S.V. of Patent RU2167125, 2001, having the following composition: Clay 70-80%, Anthracite 20-30%. The following ceramic properties:

1) the density of the ceramic product is 1100-1200 kg / m ³ ,

2) compressive strength of 8.8 to 14.6 MPa,

(3) frost resistance for 75 cycles,

4) water absorption 19.5-26.9%.

However, this frost resistance is not sufficient to allow the products to be used in aggressive conditions, and this indicator is determined by the volumetric refrigeration method, which does not model the effect of operational factors.

Patent analogue: Sadūnas A., Sveikauskaitė A., Drūlia P. Mixture for the production of frost-resistant ceramics. Patent No. LT95023, 1995. Composition of ceramics provided: clay 78-85%, sand 14.5-15%, anthracite 1-2%, fine-dispersed magnesite or dolomite or calcite 4.5-6%. The water absorption of the obtained ceramics under vacuum is 16.72-20.57%, the porous space reserve is 21.4-34.03%. o Frost resistance up to 1000 cycles. The ceramic composition of this composition would already have sufficient frost resistance, all the more so since it was determined by one-sided refrigeration according to GOST 7025-78. 5. This patent also provides a key indicator for the performance resistance to frost, a reserve of porous space that is much lower than the ceramics obtained in our research. In addition, additives such as broken window glass and coniferous sawdust were not used simultaneously in the tests described in the patents examined.

The object of the invention is to obtain wall-mounted ceramic products with higher frost resistance.

This objective was achieved by selecting the following composition by weight (in percentage by weight):

1) clay (sieved through a 0.63 mm mesh sieve) 59.2 - 72.8,

2) sand (sieved through a 0.63 mm mesh sieve) 7.2 - 10.8,

3) combusted scrap (sieved through a 1.25 mm mesh sieve) 3.2 - 4.8,

4) coniferous sawdust (sieved through a 1.25 mm mesh sieve) 10.4 - 15.6,

5) Ground window glass (screened through a 0.63 mm mesh sieve) 6.4 - 9.6.

The chemical composition of the clay is given in Table 1.

table. Chemical composition of clay

Chemical composition,% SiO ₂ Al ₂ O ₃ + TiO ₂ Fe ₂ O ₃ CaO MgO K ₂ O Na ₂ O SO ₃ Injuries 49.26 21.99 7.62 4.47 3.76 1.65 0.26 - 9.89

Granulometric composition of clay: sand particles (> 0.05 mm) content 5.12-5.84%, dust particles (0.05-0.005 mm) content 8.79-19.46%, clay particles (<0.005 mm) ) - 66.9889.59%.

The main additions to the shaping mass that give the desired effect are coniferous sawdust and ground glass. Adding more than 16% of coniferous sawdust to the sample increases defects and begins to reduce frost resistance, and less than 10% of the sawdust does not produce the desired porosity. Reducing the amount of ground glass in the molding mass to 6 percent or more prevents the production of frost-resistant ceramics, while increasing the glass content to 10 percent or more does not result in porous ceramic combs. In addition, when the amount of glass allowed in the molding compound is exceeded, the glass mass begins to diffuse to the surface, reducing the strength of the article.

Method of obtaining higher frost resistance porous ceramics:

1) preparation of raw materials (crushing, sieving),

2) mixing of components,

(3) wetting or drying the mixture to a suitable moisture content;

4) formation of semi-finished products,

5) drying and burning in optimum time and temperature mode.

The resulting wall ceramics could be used for residential or industrial buildings, especially for facades used in aggressive conditions (eg seaside). The bricks could be solid or with various voids, further reducing the thermal conductivity of the products.

The main features and advantages of the invention are set forth in Table 2.

table. Main features and advantages of the invention

Party No. Average density, kg / m ³ Water soak vacuuming, % Compressive mass strength, MPa Heat conductivity, W / mK Porous of space reserve, % Resistance frost, cycles 1 1502.4 27.06 19.18 0.37 42.88 > 300 2 1545.0 24.14 13.92 0.39 42.22 > 300 3 1577.8 21.24 15.78 0.40 38.72 > 300 4 1594.8 22.45 14.20 0.41 44.34 > 300 5 1513.8 25.49 19.47 0.38 45.14 > 300 6th 1626.6 23.49 17.82 0.42 48.22 > 300 Prototype 1150.0 - 11.70 - - 75 * Analogs - 19.40 - - 30.30 > 700

Note: The operating resistance to frost in our case was determined by one-sided refrigeration according to pr. LST EN 772-20, which exhibits a 4-5 times more aggressive disruptive effect than that found for the analogue according to GOST 7025-78, p. 5.

* Determined by volume freeze-thaw method according to GOST 7025-91.

Claims (1)

DEFINITION OF INVENTION Ceramics made of clay, lean and special additive characterized in that it is composed of 59.2-72.8% clay; lighter: 7.2-10.8% sand and 3.2-4.8% burnt scrap; special additives: 10.4% -15.6% softwood sawdust and 6.4-9.6% broken window glass.