RU2325373C2 - Method of making conglomerate engobe - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: any type of clay can be used when making conglomerate angobes, provided it can dissolve in natrium liquid glass. The clay is unfurled in water with natrium liquid glass up to 50-70% moisture. The quantity of liquid natrium glass added to the unfurled clay is equal to the quantity necessary for maximum dissolution of the watery ceramic slip with 40-45% moisture of the same clay. The unfurled clay is settled until it fully separates into sediments and a sedimental-stable suspension of clay minerals. The obtained water suspension of clay minerals, Particles of which are mot more than 1 mcm in size, are taken to the surface of the formed dry clay products, dried and are burnt in an acidic medium at temperature of 900-1050°C. An engobe-gloss coating with low water absorption capacity is obtained on the surface of the product.

EFFECT: simplified method of obtaining conglomerate engobes of various colours while using a wide range of clay types.

3 cl, 6 tbl

Description

The invention relates to the production of ceramic products for construction, cultural, domestic and artistic purposes.

A known method of preparing a sintering white engobe of the composition (wt.%): Clay, clockworker - 20, kaolin Glukhovetsky - 4, pegmatite Eliseevsky - 16, glass break - 35, chalk Belgorod - 6, quartz sand - 19 (Sakharova N.A., Cherepova OV Architectural ceramics with colored engobed layer: Publishing House of the Academy of Architecture of the Ukrainian SSR, Kiev, 1952, p.20-21). Pegmatite and glass battle are thoroughly washed in water, pegmatite is fired at a temperature of 900-960 ° C. Pregrinding of pegmatite, glass battle and chalk is carried out on runners, then, after dosing, they carry out joint wet grinding of all the starting components in a ball mill with the addition of 35% water. Fine grinding is carried out to a residue on a sieve with 10,000 holes / cm ² not more than 5%. After grinding, the suspension is filtered through a sieve of 900 holes / cm ² and diluted with water with thorough stirring to a density of 1.6-1.7 g / cm ³ . The engobe suspension is applied to cold dried products, after which the products are fired at a temperature of 900-1050 ° C.

The disadvantage of this method is its complexity because of the need to implement a sufficiently fine grinding, which allows to obtain a sintering engobe in the presence of a sufficient number of smooths in its composition.

There is a method of preparing a sintering engobe (Miklashevsky A.I. Technology of artistic ceramics. M., 1971, p.276), which consists in taking 250 g of clay and dissolving it in 1 liter of distilled or rain water with the addition of 5 g of crystalline soda . After this, the clay is allowed to stand for a day. Some clays after settling are separated into a clear liquid and sediment, such are not suitable for the preparation of sintering engobe. After a day of settling, others are separated into a precipitate and an aqueous suspension, the suspension is drained, partially evaporated and then used as an anobic suspension to be applied to the surface of molded ceramic products. After drying and firing in an oxidizing medium at temperatures of 900-1000 ° C, the products get a glossy engobe coating with a low water absorption, its color can be white, beige or red, depending on the amount of coloring oxides present in the engobe suspension. The disadvantages of this method of preparation of sintering engobe are - a limited range of used clays or mixtures thereof, the complexity because of the need to involve additional operations - evaporation.

The technical task of the invention is to develop a simple method for producing sintering engobes of various colors using an expanded assortment of used clays.

To solve the problem in the method of preparing sintering engobe, it is proposed to use any clay that can liquefy with sodium liquid glass, which is dissolved in water with this electrolyte to a moisture content of 50-70%. Sodium water glass is taken as much as it is necessary to add it to the water slurry of relative humidity 40-45% from the same clay in order to minimize the slip. The technique for determining the amount of electrolyte required for maximum slip fluidity (minimum slip expiration time) using an Angler viscometer is given in the book “Technical Analysis and Control of Ceramics Production”. Lukin E.S., Andrianov N.T., M.,: Stroyizdat. - 1975 - p.115 [1]. Dissolved clay is defended until complete separation into sediment and sedimentation-resistant suspension of clay minerals. The resulting aqueous suspension of clay minerals, particles of not more than 1 μm in size, is applied to the surface of molded dry ceramic products, dried and fired in an oxidizing medium at a temperature of 900-1050 ° C, obtaining an engob-gloss coating with low water absorption, composition (in in terms of calcined substance, wt.%):

Al ₂ O ₃ - 13 ÷ 5-35

Fe ₂ O ₃ + FeO - 0.01 ÷ 15

TO ₂ - 0.01 ÷ 5

CaO - 0.1 ÷ 8

MgO - 0.1 ÷ 8

K ₂ O - 0.5 ÷ 5

Na ₂ O - 0.5 ÷ 5

SiO ₂ - the rest

In the inventive method for the preparation of sintering engobe, a large assortment of clays is used, which is its undoubted advantage over the prototype and analogues. Clays of the following deposits were taken as initial clays for preparing sintering engobe - Vladimirsky (Rostov Region), Ilsky (Krasnodar Territory), Starokorsunsky (Krasnodar Territory). The first clay is suitable for the production of fine and sanitary-building ceramics, the second and third - fusible, with a high content of coloring oxides, are used for the production of ceramic bricks by plastic molding. Tables 1, 2, 3 show the results of settling loose clay with different humidity and different amounts of sodium liquid glass of density 1.4 g / ml with silicate module 2.80 per 1 kg of dry clay in a container 0.5 m high for three days , respectively, for clays of Vladimir, Ilsk and Starokorsun deposits.

As can be seen from tables 1-3, compositions No. 2, 3, 4, 5, 10, 15 for each of the three clays, after settling, were divided into a clear liquid and sediment. Compositions No. 1, 6, 11, 12, 13, for each of the three clays, after settling according to visual characteristics, did not change and remained sedimentation-resistant suspensions. Compositions No. 7, 8, 9, 14, for each of the three clays, after settling, were divided into sedimentation-resistant suspensions and sediments. It was experimentally found that the maximum fluidity of aqueous slurries of relative humidity from 40 to 45% from clays of the Vladimir, Ilsk and Starokorsun deposits, determined using an Angler viscometer, is also achieved at 15 ml, 8 ml and 12 ml of sodium liquid glass per 1 kg dry clay, with a density of water glass of 1.4 g / ml and a silicate module of 2.80 [1]. Of all the sedimentation-stable suspensions obtained as a result of sedimentation from compositions No. 1, 6, 7, 8, 98, 11, 12, 13, 14, for the examined three clays, plates 1-3 cm thick were formed by slip casting into plaster molds. After drying, the plates were fired at a temperature of 900 ° C in an oxidizing medium. After firing, the water absorption of the plates was measured according to the method described in GOST 530-95. Table 4 shows the measurement results. From table 4 it is seen that the plates made from compositions No. 7, 8, 9 of all three clays have the lowest water absorption. These compositions have a moisture content of 50 to 70%, the amount of electrolyte is 8-15 ml per 1 kg of dry clay. Low water absorption is ensured by the size of not more than 1 μm particles of clay minerals in suspensions.

Table 5 shows the results of measuring the water absorption of plates formed from suspensions obtained as a result of settling of compositions No. 7, 8, 9 and calcined in an oxidizing medium at temperatures of 900 ° C, 950 ° C, 1000 ° C, 1050 ° C, 1100 ° C . From table No. 5 it is seen that the highest value of water absorption does not exceed 0.2% for compositions No. 7, examined three clays, after firing at a temperature of 900 ° C. At higher temperatures, the water absorption does not exceed 0.1%. Given that the products of building, cultural, household and artistic ceramics are fired at temperatures of 900 ° -1050 ° C, from the data of table No. 5, we can conclude that the use of suspension compositions No. 7, 8, 9 as an engobe suspension for these products after firing at these temperatures it will allow to obtain a coating on the surface - an engobe with low water absorption. Raising to 1100 ° C the firing temperature of products of building and household ceramics, the main component of which are low-melting clay, often leads to deformation of the products.

Plates made from compositions No. 1, 6, 11, 12, 13 have high water absorption, since large particles did not precipitate in suspensions of these compositions. Plates made from compositions No. 14 have an intermediate result, which is due to the incomplete deposition of large particles due to an excess of sodium liquid glass, which caused the thickening of suspensions.

Compositions No. 2, 3, 4, 5, 10, 15 from tables 1-3 after repeated mixing were applied to dried ceramic products and burned in an oxidizing medium at 900-1050 ° C. The coatings had composition characteristics No. 1 in Table 4, i.e. they were not sintering engobes, and therefore, it is not practical to use them as engobes.

Compositions No. 7, 8, 9, three clays, after firing, have a minimum water absorption not exceeding 0.2% for all three clays examined. These suspensions were applied to the surface of molded dry ceramic products, after which the products were fired in an oxidizing medium at a temperature of 900-1050 ° C. After firing, the products acquired a glossy coating with low water absorption.

Based on the experiments, we can conclude: the amount of sodium liquid added to the dissolved clay and its moisture depends on the particles of what sizes will be in a sedimentation-resistant suspension of clay minerals that are applied to ceramic products.

After firing, the color of the glossy coating obtained when used as the original - Vladimir clay was white, for the Ilskoy and Starokorsunskaya clays - red-brick.

Table 6 shows the chemical composition (wt.%) Of engobes with low water absorption, obtained from Vladimir, Ilsk and Starokorsun clays.

Based on the foregoing, we conclude that the inventive method for the preparation of sintering engobe has novelty, inventive step and is industrially applicable.

Table 1 Compositions of suspensions from Vladimir clay Composition number Humidity of dissolved clay,% Number of water glass, ml per 1 kg of dry clay Visual characteristic of settled dissolving clay one 40 7.5 Sedimentation-resistant suspension 2 fifty 7.5 Clear liquid and precipitate 3 60 7.5 Clear liquid and precipitate four 70 7.5 Clear liquid and precipitate 5 80 7.5 Clear liquid and precipitate 6 40 fifteen Sedimentation-resistant suspension 7 fifty fifteen Sedimentation-resistant suspension and sediment 8 60 fifteen Sedimentation-resistant suspension and sediment 9 70 fifteen Sedimentation-resistant suspension and sediment 10 80 fifteen Clear liquid and precipitate eleven 40 22.5 Sedimentation-resistant suspension 12 fifty 22.5 Sedimentation-resistant suspension 13 60 22.5 Sedimentation-resistant suspension fourteen 70 22.5 Sedimentation-resistant suspension and sediment fifteen 80 22.5 Clear liquid and precipitate

table 2 Compositions of suspensions from Ilsky clay Composition number Humidity of dissolved clay,% Number of water glass, ml per 1 kg of dry clay Visual characteristic of settled dissolving clay one 40 four Sedimentation-resistant suspension 2 fifty four Clear liquid and precipitate 3 60 four Clear liquid and precipitate four 70 four Clear liquid and precipitate 5 80 four Clear liquid and precipitate 6 40 8 Sedimentation-resistant suspension 7 fifty 8 Sedimentation-resistant suspension and sediment 8 60 8 Sedimentation-resistant suspension and sediment 9 70 8 Sedimentation-resistant suspension and sediment 10 80 8 Clear liquid and precipitate eleven 40 12 Sedimentation-resistant suspension 12 fifty 12 Sedimentation-resistant suspension 13 60 12 Sedimentation-resistant suspension fourteen 70 12 Sedimentation-resistant suspension and sediment fifteen 80 12 Clear liquid and precipitate

Table 3 Compositions of suspensions from Starokorsunsky clay Composition number Humidity of dissolved clay,% Number of water glass, ml per 1 kg of dry clay Visual characteristic of settled dissolving clay one 40 6 Sedimentation-resistant suspension 2 fifty 6 Clear liquid and precipitate 3 60 6 Clear liquid and precipitate four 70 6 Clear liquid and precipitate 5 80 6 Clear liquid and precipitate 6 40 12 Sedimentation-resistant suspension 7 fifty 12 Sedimentation-resistant suspension and sediment 8 60 12 Sedimentation-resistant suspension and sediment 9 70 12 Sedimentation-resistant suspension and sediment 10 80 12 Clear liquid and precipitate eleven 40 eighteen Sedimentation-resistant suspension 12 fifty eighteen Sedimentation-resistant suspension 13 60 eighteen Sedimentation-resistant suspension fourteen 70 eighteen Sedimentation-resistant suspension and sediment fifteen 80 eighteen Clear liquid and precipitate

Table 4 Values of water absorption of fired plates Composition number Water absorption of the plates after firing,% Vladimir clay plates Plates from Ilsky clay Starokorsun clay plates one 9 fifteen 17 6 9 fifteen 17 7 <0.2 <0.2 <0.2 8 <0.1 <0.1 <0.1 9 <0.1 <0.1 <0.1 eleven 9 fifteen 17 12 9 fifteen 17 13 9 fifteen 17 fourteen 5 8 10

Table 5 The values of water absorption of the plates made of settled compounds No. 7, 8, 9 Composition number Firing temperature, deg. FROM Water absorption of the plates,% Vladimir clay plates Plates from Ilsky clay Starokorsun clay plates 7 900 <0.2 <0.2 <0.2 8 900 <0.1 <0.1 <0.1 9 900 <0.1 <0.1 <0.1 7 950 <0.1 <0.1 <0.1 8 950 <0.1 <0.1 <0.1 9 950 <0.1 <0.1 <0.1 7 1000 <0.1 <0.1 <0.1 8 1000 <0.1 <0.1 <0.1 9 1000 <0.1 <0.1 <0.1 7 1050 <0.1 <0.1 <0.1 8 1050 <0.1 <0.1 <0.1 9 1050 <0.1 <0.1 <0.1 7 1100 <0.1 <0.1 <0.1 8 1100 <0.1 <0.1 <0.1 9 1100 <0.1 <0.1 <0.1

Table 6 The chemical composition of engobes Source clay SiO ₂ Al ₂ O ₃ Fe ₂ O ₃ TiO ₂ Cao MgO K ₂ O Na ₂ O Vladimirskaya 62.40 29.08 0.46 1.13 0.59 1,52 2.80 2.02 Ilskaya 55.69 21.63 9.46 1.15 1.09 4.91 3.83 2.24 Starokorsunskaya 58.41 19.82 7.34 0.57 5.42 3.18 2.43 2.83

Claims (3)

1. The method of preparation of sintering engobe, including the dissolution of clay in water with the addition of sodium electrolyte, sedimentation, separation into an aqueous suspension and precipitate, applying the suspension to the surface of dry ceramic products, drying and firing in an oxidizing environment, characterized in that the sodium electrolyte is used sodium liquid glass, take any clay that can liquefy with sodium liquid glass, the humidity of the dissolved clay is 50-70%, the amount of liquid sodium glass added to the dissolving clay Is equal to the maximum required to liquefy the aqueous ceramic slurry humidity 40-45% of the same clay, sedimentation is carried out prior to separation into sludge and sedimentation stable aqueous suspension having particles less than 1 micron. 2. The method according to claim 1, characterized in that the sodium liquid glass is added to water before the dissolution of clay to a moisture content of 50-70%. 3. The method according to claim 1, characterized in that the firing temperature is not more than 1050 ° C.