CA1148982A - Compositions and methods for producing clayware - Google Patents
Compositions and methods for producing claywareInfo
- Publication number
- CA1148982A CA1148982A CA000374926A CA374926A CA1148982A CA 1148982 A CA1148982 A CA 1148982A CA 000374926 A CA000374926 A CA 000374926A CA 374926 A CA374926 A CA 374926A CA 1148982 A CA1148982 A CA 1148982A
- Authority
- CA
- Canada
- Prior art keywords
- boron
- flux
- zeolite
- aluminosilicate
- clayware
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- Glass Compositions (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
Clayware is produced by firing a composition con-taining clay and a boron-containing flux, wherein the flux is a synthetic alkali metal and/or alkaline earth metal alumino-silicate having the crystal structure of a zeolite and containing boron entrapped within that structure. The boronated zeolite flux can be prepared in a form in which it can be used directly in the manufacture of clayware, especially earthenware.
Clayware is produced by firing a composition con-taining clay and a boron-containing flux, wherein the flux is a synthetic alkali metal and/or alkaline earth metal alumino-silicate having the crystal structure of a zeolite and containing boron entrapped within that structure. The boronated zeolite flux can be prepared in a form in which it can be used directly in the manufacture of clayware, especially earthenware.
Description
1~8982 This invention relates to a method of making clayware and in particular to the use of a novel flux for making clay-ware.
Clayware such as porcelain, bone china, earthenware, the so-called ironstones, aluminous ceramics, hotel wares and ceramic tiles, is produced by firing a composition containing clay and flux.
Fluxes conventionally used in making clayware, such as exemplified above, are feldspars, nepheline syenite and Cornish stone. U.S. Patent 3,704,146 describes fluxes for "white~ware" ceramic compositions comprising clay, flint and a flux, the fluxes being ground vitreou~ frits which may contain up to about 45% by weight of boric oxide. U.S. Patent 4,219,360 describes use of B2O3 containing frits in manufac-turing bone china. However, a frit i9 expensive to produce because of the energy consumption, the need for refractory furnace linings and because of the need to grind the product.
Furthermore, the frits have been found not to be suitable for some clayware compositions due to slight leaching of boric oxide from the frit during manufacture of ceramic articles, for example, in preparing casting slips. U.S. Patents 3,303,036 and 3,532,522 also describe use of inorganic borates in manufacturing ceramic ware.
Zeolites have been proposed as components of ceramic compositions especially in the production of lightweight cera-mics~ See, for example, Japanese Patent Nos. 69 23,815, 69 23,816 and 69 23,817 of Y. Ookawa all published October 9, 1969 (Chem. Abs. 79, 15378, 15352 and 15350 respectively), Onoda Cement Co., Ltd. published June 11, 1973, (Chem. Abs. 79, 96,191). Howe~er, none of the zeolites are known to contain `~F
w-- .
A
1~898Z
boron and the zeolites are used to confer refractory pro-perties on the ceramics and are not used as fluxes.
The present invention provides a method of making a clayware by firing a composition containing clay and a boron-containin~ flux, wherein the flux i8 a synthetic alkali metal and/or alkaline earth metal aluminosilicate having the crystal structure of a zeolite and containing boron entrapped within that structure. For convenience, the flux to be used in accordance with the invention will be referred to as a "boronated zeolite".
The boron component of the boronated zeolite is less soluble than that of the ground vitreous frits. Thus, when entrapped in a zeolitic structure, boron in its oxide .
~ 19L8982 1 form may be incorporated into clayware compositions in a
Clayware such as porcelain, bone china, earthenware, the so-called ironstones, aluminous ceramics, hotel wares and ceramic tiles, is produced by firing a composition containing clay and flux.
Fluxes conventionally used in making clayware, such as exemplified above, are feldspars, nepheline syenite and Cornish stone. U.S. Patent 3,704,146 describes fluxes for "white~ware" ceramic compositions comprising clay, flint and a flux, the fluxes being ground vitreou~ frits which may contain up to about 45% by weight of boric oxide. U.S. Patent 4,219,360 describes use of B2O3 containing frits in manufac-turing bone china. However, a frit i9 expensive to produce because of the energy consumption, the need for refractory furnace linings and because of the need to grind the product.
Furthermore, the frits have been found not to be suitable for some clayware compositions due to slight leaching of boric oxide from the frit during manufacture of ceramic articles, for example, in preparing casting slips. U.S. Patents 3,303,036 and 3,532,522 also describe use of inorganic borates in manufacturing ceramic ware.
Zeolites have been proposed as components of ceramic compositions especially in the production of lightweight cera-mics~ See, for example, Japanese Patent Nos. 69 23,815, 69 23,816 and 69 23,817 of Y. Ookawa all published October 9, 1969 (Chem. Abs. 79, 15378, 15352 and 15350 respectively), Onoda Cement Co., Ltd. published June 11, 1973, (Chem. Abs. 79, 96,191). Howe~er, none of the zeolites are known to contain `~F
w-- .
A
1~898Z
boron and the zeolites are used to confer refractory pro-perties on the ceramics and are not used as fluxes.
The present invention provides a method of making a clayware by firing a composition containing clay and a boron-containin~ flux, wherein the flux i8 a synthetic alkali metal and/or alkaline earth metal aluminosilicate having the crystal structure of a zeolite and containing boron entrapped within that structure. For convenience, the flux to be used in accordance with the invention will be referred to as a "boronated zeolite".
The boron component of the boronated zeolite is less soluble than that of the ground vitreous frits. Thus, when entrapped in a zeolitic structure, boron in its oxide .
~ 19L8982 1 form may be incorporated into clayware compositions in a
2 water insoluble form and can contribute its valuable fluxing
3 properties without detriment to the clayware products or to
4 their methods of manufacture. It may have been predicted that the sodium oxide content of a sodium aluminosilicate 6 zeolite, such as sodalite hydrate, would contribute to the 7 fluxing properties of the material but it has been found that 8 this effect is not significant. However, it has clearly been 9 demonstrated that when boron is incorporated in the structure, the resultant material becomes an unexpectedly powerful flux.
11 This is possibly because temperatures attained in clayware 12 manufacture are not sufficiently high to melt a zeolite and 13 activate its sodium oxide content as a flux; but when boric 14 oxide is also present that melting point is decreased allowing sodium oxide and boric oxide to flux with synergistic effect.
17 Although the material used as flux according to 18 the present invention is termed "boronated zeolite" it should ~9 be appreciated that the presence of boron in the boronated zeolite so reduces the water absorption capacity of the 21 material that it could be considered feldspathoidal rather 22 than zeolitic. -24 A boron-containing zeolite has previously been disclosed (J. Chem. Soc. (A) 1970, pp. 1516-23) and the use 26 of boron to accelerate zeolite formation without leaving 27 boron in the zeolite structure has also been disclosed 28 (German OS 24 50 708). The present invention resides in 29 the use of the boronated zeolite as one component, a flux, of a composition for making clayware.
32 A preferred example of clayware in which the I
. ..~
1148~8Z
1 boronated zeolite can be used as flux is earthenware when a 2 composition containing ball clay, china clay, flint and the 3 boronated zeolite is fired. Other types of clayware in 4 which the boronated zeolite is valuable as a flux are porcelain, bone china, ironstones and hotel wares as well 6 as ceramic tiles. Thus, for example, bone china can be 7 prepared by firing, usually at a temperature below about 8 1200C., preferably about 1180C.j a composition comprising -9 calcined bone, china clay and the boronated zeolite.
10 ~ .
11 The boronated zeolite can be synthesised in the 12 form of fine crystals, for example having a particle size 13 below 5 microns, which are of a size very suitable for use 14 in the production of clayware. There is thus no need to 15 resort to grinding as with the vitreous frits previously .
16 used as boron-containing fluxes. In addition, it has been 17 found that bone china made according to this invention with 18 a boronated zeolite flux has a translucency at least equal 19 to that of bone china made with a conventional flux and that this translucency can be achieved at a lower firing temperature 21 and in a shorter firing time.
23 The boronated zeolite flux used according to the 24 present invention can be made by any of the conventional processes for hydrothermal crystallisation of zeolites, for 26 example sodalite hydrate, from a source of silica, a source 27 of alumina and a source of alkali metal or alkaline earth 28 metal (such as sodium,-calcium, potassium, magnesium, 29 lithium, but preferably a source of sodium), but with a source of boron such as boric acid or a sodium borate in 31 the synthesis mixture: The resultant zeolite has a B2O3 32 content of about 2 to 10 per cent by weight, preferably I
. ~ 8982 1 about 3 to 7.5 per cent B2O3.
3 Two examples of the production of a boronated zeolite 4 are as follows:
S . ' 6 Example 1 8 1712 g. sodium hydroxide and 751 g. borax decahydrate 9 were dissolved in 4000 g. distilled water in a stainless steel beaker. 1085 g. china clay having a particle size below 1 11 micron were added and the mixture was stirred for 24 hours 12 at 85C. (From observation, it appeared that 24 hours for 13 crystallisation was more than needed; crystallisation appeared 14 to be complete after about 6 hours.) After filtering, washing well with distilled water, and drying overnight at 130C., .
16 1175 g. of product were obtained. Its X-ray diffraction 17 powder pattern was substantially identical to that of the 18 mineral nosean confirming the skeletal structure of the 19 cage around the boron atom. Chemical analysis showed that the product contained 20.5% Na2O, 5.0~ B2O3, 31.4~ A12O3 and 21 39.8~ ~iO2, the balance being water ~all percentages being by 22 weight). The particle size was mostly less than 5 microns.
2~ 10 g. of product were stlrred with 100 g. distilled water for 24 6 hours at 25C but no more than one fiftieth of the B2O3 was 25 leached out.
27 Example 2 29 A boronated zeolite having the same properties as that produced by the method of Example 1 was made using sodium 31 aluminate and sodium silicate as the source of alumina and 32 l ¦ sil a, instead of china clay . ., I - ~48g8~
1 The following Examples illustrate the present inven-2 tion.
4 Example 3 ' 6 The boronated zeolite made by Example 1 was mixed 7 with china clay and calcined bone to form a body mix for 8 making bone china of the following composition:
9 Calcined bone 55 parts by weight China clay 25 parts by weight 11 ¦ Boronated zeolite 20 parts by weight 12 ¦ ' This mix was made into a casting slip with 50 parts 13 of water using Dispex N40 (a polyacrylate) as deflocculant.
14 Discs 4.4 cm. in diameter x 0.3 cm. were cast and, after drying, were fired using a heating rate of 150C/hour to a 16 ~inal temperature of 1180C. After holding at this temperature 17 for 2 hours, the discs were allowed to cool slowly. The 18 apparent porosity wa's found to be 2.1% and the translucency 19 was found to be 40% more than that of a standard bone china fired at 1250C. Translucency is expressed as the amount of ' 21 light transmitted compared with standard bone china fired at 22 1250C.
23 ' 24 Example 4 26 To illustrate the advantages of the boronated 27 zeolites as fluxes for clayware, comparative trials were 28 carried out between body mixes containing the boronated 29 zeolite of Example 1 and body mixes containing respectively as fluxes sodalite and "Zeolite A".
31 .
32 The procedure was as follows:
.
:_ - .
. . ~
1 Body mixes were prepared to the following composition:
2 Calcined bone 55 parts by weight 3 China clay 25 parts by weight 4 Flux 20 parts by weight 200 g. of the body mix were blunged with 100 ml. of 6 water to form a slip. Dispex N40 was used as deflocculant.
8 Discs 4.4 cm. diameter x 0.3 cm. were cast, dried 9 and fired to various temperatures at a heating rate of 150C/hr.
The discs were held for 2 hours at each temperature and then 11 allowed to cool. After cooling, translucency and apparent 2 porosity measurements were carried out.
14 The results were as shown in Table 1.
27~
28 , 29 ' 31 l ~ _7_ l l . , - - - - . ~ -~ lL4898Z
11 ~
s ~ ~
10 ¦ a ~ ~ u 4 1 I ~ ~ 9 ~ o. ~ ' ~ ~1 r~ ~ ~r O
17 1~ ~ ~ l o~
~ ~~ ~D ~D ' ~
~ .~~ ~ r~ ~
2 1 ¦ ~ ~ ¦ N ¦ ~ l 23 O rl~1 ~ oo ~ . :
2a 31 .
~ ~898~
1 These results indicate that neither "Zeolite A" nor 2 sodalite is a suitable flux material.
4 The boronated zeolite shows good fluxing properties at the firing temperature of 1180C. Discs fired at the 6 higher temperatures of 1220 and 1255C. were found to be 7 badly bloated and distorted indicating overfiring.
9 Discs containing "Zeolite Al' or sodalite were not adequately fired even at 1255C. as indicated by high apparent 11 porosity and low translucency.
13 Examples 5-7 Trials were carried out comparing earthenware body 16 mixes containing a boronated zeolite with a standard earthenware 17 body mix.
19 Body mixes were prepared to the following compositions in which parts are by weight:
A* B C D* E*
22 Ball clay 25 25 25 25 25 23 China clay 25 25 25 25 25 Flint 35 35 35 35 35 24 Cornish stone 15 Zeolite - 3 S 5 5 26 ~hese mixes were made up as castins slips as follows:
A* B C D* E*
27 Ball clay 50 50 50 50 50 28 China clay 50 50 50 50 50 Flint 70 70 70 ~70 70 29 Cornish stone 30 - - - -Zeolite - 6 10 10 10 31 Water 95 90 80 80 80 32 Dispex N40 0.8 0.8 0.8 0.8 0.8 *Comparative . ~, ~ 1148~8Z
1 Discs 4.4 cm. diameter x 0.3 cm. were cast from 2 each slip, dried and fired according to the following Examples.
3 (Zeolite in B and C = boronated zeolite: in D = sodalite 4 hydrate: in E = Zeolite A) 6 Example 5 8 Discs were fired at different temperatures as shown 9 in Table 2 in a gradient kiln at a heating rate of 300C. per hour and then allowed to cool. Apparent porosity and bulk 11 density measurements were carried out after cooling. The 12 results obtained are shown in Table 2.
13 , _ 17 (a) Apparent Porosity %
_ 18 Temp (C.) A* B C D* E*
19 1205 12.0 10.0 2.5 9.2 13.6 1155 18.9 15.3 12.4 15.6 20.1 21 1095 26.8 22.9 19.0 22 7 26.7 23 (b) Bulk density g/cm3 24 Temp (C.) A* B C D^ E*
1205 2.20 2.22 2.29 2.24 2.16 26 llS5 2.07 2.14 2.19 2.14 2.05 27 1095 1.88 1.99- 2.06 1.99 1.89 28 *Comparative 29 Example 6 31 Example 5 was repeated but the discs were given a one 32 hour soak at the highest temperature. As before, apparent ?
. . .
~1~8~8Z
1 porosity and bulk density measurements were carried out after 2 cooling. The results obtained are shown in Table 3.
S
S Rpparent porosity % Bulk density g/cm 7 Temp (C.) A* B C A* B C
9 1265 6.64.5 0.052.272.27 2.32 1240 9.07.6 0.062.242.26 2.31 1195 13.411.6 6.12.18 2.21 2.28 11 .
13 Example 7 Discs were fired at different temperatures in a gradi,ent 16 kiln at a heating rate of 50C. per hour with a two hour soak at 17 the highest temperature. Apparent porosity and bulk density , 18 measurements were carried out. The results are shown in Table 4.
22 ~ Apparent porosity ~ Bulk density g/cm 23 Temp (C.) A* B C A~ B C
1155 17.7 17.3 11.5 2.09 2.11 2.20 L140 18.7 18.0 12.6 2.07 2.09 2.18 26 1105 23.7 21.3 17.3 1.97 2.03 2.10 27 1080 27.8 24.7 20.8 1.87 1.95 2.03 28 *Comparative The results obtained in Tables 2 to 4 clearly demon-31 strate improvements achieved using a boronated zeolite as a flux 32 in fired earthenware products compared with the known flux Cornish stone. -11--- - _ ~1~898Z
1 Various changes and modifications of the invention .
2 can be made and, to the extent that such variations incorporate 3 the spirit of this invention, they are intended to be included ~ ~ he ~ ~ n~ 3 28 . ~.
.
31 .
__ .
11 This is possibly because temperatures attained in clayware 12 manufacture are not sufficiently high to melt a zeolite and 13 activate its sodium oxide content as a flux; but when boric 14 oxide is also present that melting point is decreased allowing sodium oxide and boric oxide to flux with synergistic effect.
17 Although the material used as flux according to 18 the present invention is termed "boronated zeolite" it should ~9 be appreciated that the presence of boron in the boronated zeolite so reduces the water absorption capacity of the 21 material that it could be considered feldspathoidal rather 22 than zeolitic. -24 A boron-containing zeolite has previously been disclosed (J. Chem. Soc. (A) 1970, pp. 1516-23) and the use 26 of boron to accelerate zeolite formation without leaving 27 boron in the zeolite structure has also been disclosed 28 (German OS 24 50 708). The present invention resides in 29 the use of the boronated zeolite as one component, a flux, of a composition for making clayware.
32 A preferred example of clayware in which the I
. ..~
1148~8Z
1 boronated zeolite can be used as flux is earthenware when a 2 composition containing ball clay, china clay, flint and the 3 boronated zeolite is fired. Other types of clayware in 4 which the boronated zeolite is valuable as a flux are porcelain, bone china, ironstones and hotel wares as well 6 as ceramic tiles. Thus, for example, bone china can be 7 prepared by firing, usually at a temperature below about 8 1200C., preferably about 1180C.j a composition comprising -9 calcined bone, china clay and the boronated zeolite.
10 ~ .
11 The boronated zeolite can be synthesised in the 12 form of fine crystals, for example having a particle size 13 below 5 microns, which are of a size very suitable for use 14 in the production of clayware. There is thus no need to 15 resort to grinding as with the vitreous frits previously .
16 used as boron-containing fluxes. In addition, it has been 17 found that bone china made according to this invention with 18 a boronated zeolite flux has a translucency at least equal 19 to that of bone china made with a conventional flux and that this translucency can be achieved at a lower firing temperature 21 and in a shorter firing time.
23 The boronated zeolite flux used according to the 24 present invention can be made by any of the conventional processes for hydrothermal crystallisation of zeolites, for 26 example sodalite hydrate, from a source of silica, a source 27 of alumina and a source of alkali metal or alkaline earth 28 metal (such as sodium,-calcium, potassium, magnesium, 29 lithium, but preferably a source of sodium), but with a source of boron such as boric acid or a sodium borate in 31 the synthesis mixture: The resultant zeolite has a B2O3 32 content of about 2 to 10 per cent by weight, preferably I
. ~ 8982 1 about 3 to 7.5 per cent B2O3.
3 Two examples of the production of a boronated zeolite 4 are as follows:
S . ' 6 Example 1 8 1712 g. sodium hydroxide and 751 g. borax decahydrate 9 were dissolved in 4000 g. distilled water in a stainless steel beaker. 1085 g. china clay having a particle size below 1 11 micron were added and the mixture was stirred for 24 hours 12 at 85C. (From observation, it appeared that 24 hours for 13 crystallisation was more than needed; crystallisation appeared 14 to be complete after about 6 hours.) After filtering, washing well with distilled water, and drying overnight at 130C., .
16 1175 g. of product were obtained. Its X-ray diffraction 17 powder pattern was substantially identical to that of the 18 mineral nosean confirming the skeletal structure of the 19 cage around the boron atom. Chemical analysis showed that the product contained 20.5% Na2O, 5.0~ B2O3, 31.4~ A12O3 and 21 39.8~ ~iO2, the balance being water ~all percentages being by 22 weight). The particle size was mostly less than 5 microns.
2~ 10 g. of product were stlrred with 100 g. distilled water for 24 6 hours at 25C but no more than one fiftieth of the B2O3 was 25 leached out.
27 Example 2 29 A boronated zeolite having the same properties as that produced by the method of Example 1 was made using sodium 31 aluminate and sodium silicate as the source of alumina and 32 l ¦ sil a, instead of china clay . ., I - ~48g8~
1 The following Examples illustrate the present inven-2 tion.
4 Example 3 ' 6 The boronated zeolite made by Example 1 was mixed 7 with china clay and calcined bone to form a body mix for 8 making bone china of the following composition:
9 Calcined bone 55 parts by weight China clay 25 parts by weight 11 ¦ Boronated zeolite 20 parts by weight 12 ¦ ' This mix was made into a casting slip with 50 parts 13 of water using Dispex N40 (a polyacrylate) as deflocculant.
14 Discs 4.4 cm. in diameter x 0.3 cm. were cast and, after drying, were fired using a heating rate of 150C/hour to a 16 ~inal temperature of 1180C. After holding at this temperature 17 for 2 hours, the discs were allowed to cool slowly. The 18 apparent porosity wa's found to be 2.1% and the translucency 19 was found to be 40% more than that of a standard bone china fired at 1250C. Translucency is expressed as the amount of ' 21 light transmitted compared with standard bone china fired at 22 1250C.
23 ' 24 Example 4 26 To illustrate the advantages of the boronated 27 zeolites as fluxes for clayware, comparative trials were 28 carried out between body mixes containing the boronated 29 zeolite of Example 1 and body mixes containing respectively as fluxes sodalite and "Zeolite A".
31 .
32 The procedure was as follows:
.
:_ - .
. . ~
1 Body mixes were prepared to the following composition:
2 Calcined bone 55 parts by weight 3 China clay 25 parts by weight 4 Flux 20 parts by weight 200 g. of the body mix were blunged with 100 ml. of 6 water to form a slip. Dispex N40 was used as deflocculant.
8 Discs 4.4 cm. diameter x 0.3 cm. were cast, dried 9 and fired to various temperatures at a heating rate of 150C/hr.
The discs were held for 2 hours at each temperature and then 11 allowed to cool. After cooling, translucency and apparent 2 porosity measurements were carried out.
14 The results were as shown in Table 1.
27~
28 , 29 ' 31 l ~ _7_ l l . , - - - - . ~ -~ lL4898Z
11 ~
s ~ ~
10 ¦ a ~ ~ u 4 1 I ~ ~ 9 ~ o. ~ ' ~ ~1 r~ ~ ~r O
17 1~ ~ ~ l o~
~ ~~ ~D ~D ' ~
~ .~~ ~ r~ ~
2 1 ¦ ~ ~ ¦ N ¦ ~ l 23 O rl~1 ~ oo ~ . :
2a 31 .
~ ~898~
1 These results indicate that neither "Zeolite A" nor 2 sodalite is a suitable flux material.
4 The boronated zeolite shows good fluxing properties at the firing temperature of 1180C. Discs fired at the 6 higher temperatures of 1220 and 1255C. were found to be 7 badly bloated and distorted indicating overfiring.
9 Discs containing "Zeolite Al' or sodalite were not adequately fired even at 1255C. as indicated by high apparent 11 porosity and low translucency.
13 Examples 5-7 Trials were carried out comparing earthenware body 16 mixes containing a boronated zeolite with a standard earthenware 17 body mix.
19 Body mixes were prepared to the following compositions in which parts are by weight:
A* B C D* E*
22 Ball clay 25 25 25 25 25 23 China clay 25 25 25 25 25 Flint 35 35 35 35 35 24 Cornish stone 15 Zeolite - 3 S 5 5 26 ~hese mixes were made up as castins slips as follows:
A* B C D* E*
27 Ball clay 50 50 50 50 50 28 China clay 50 50 50 50 50 Flint 70 70 70 ~70 70 29 Cornish stone 30 - - - -Zeolite - 6 10 10 10 31 Water 95 90 80 80 80 32 Dispex N40 0.8 0.8 0.8 0.8 0.8 *Comparative . ~, ~ 1148~8Z
1 Discs 4.4 cm. diameter x 0.3 cm. were cast from 2 each slip, dried and fired according to the following Examples.
3 (Zeolite in B and C = boronated zeolite: in D = sodalite 4 hydrate: in E = Zeolite A) 6 Example 5 8 Discs were fired at different temperatures as shown 9 in Table 2 in a gradient kiln at a heating rate of 300C. per hour and then allowed to cool. Apparent porosity and bulk 11 density measurements were carried out after cooling. The 12 results obtained are shown in Table 2.
13 , _ 17 (a) Apparent Porosity %
_ 18 Temp (C.) A* B C D* E*
19 1205 12.0 10.0 2.5 9.2 13.6 1155 18.9 15.3 12.4 15.6 20.1 21 1095 26.8 22.9 19.0 22 7 26.7 23 (b) Bulk density g/cm3 24 Temp (C.) A* B C D^ E*
1205 2.20 2.22 2.29 2.24 2.16 26 llS5 2.07 2.14 2.19 2.14 2.05 27 1095 1.88 1.99- 2.06 1.99 1.89 28 *Comparative 29 Example 6 31 Example 5 was repeated but the discs were given a one 32 hour soak at the highest temperature. As before, apparent ?
. . .
~1~8~8Z
1 porosity and bulk density measurements were carried out after 2 cooling. The results obtained are shown in Table 3.
S
S Rpparent porosity % Bulk density g/cm 7 Temp (C.) A* B C A* B C
9 1265 6.64.5 0.052.272.27 2.32 1240 9.07.6 0.062.242.26 2.31 1195 13.411.6 6.12.18 2.21 2.28 11 .
13 Example 7 Discs were fired at different temperatures in a gradi,ent 16 kiln at a heating rate of 50C. per hour with a two hour soak at 17 the highest temperature. Apparent porosity and bulk density , 18 measurements were carried out. The results are shown in Table 4.
22 ~ Apparent porosity ~ Bulk density g/cm 23 Temp (C.) A* B C A~ B C
1155 17.7 17.3 11.5 2.09 2.11 2.20 L140 18.7 18.0 12.6 2.07 2.09 2.18 26 1105 23.7 21.3 17.3 1.97 2.03 2.10 27 1080 27.8 24.7 20.8 1.87 1.95 2.03 28 *Comparative The results obtained in Tables 2 to 4 clearly demon-31 strate improvements achieved using a boronated zeolite as a flux 32 in fired earthenware products compared with the known flux Cornish stone. -11--- - _ ~1~898Z
1 Various changes and modifications of the invention .
2 can be made and, to the extent that such variations incorporate 3 the spirit of this invention, they are intended to be included ~ ~ he ~ ~ n~ 3 28 . ~.
.
31 .
__ .
Claims (10)
1. A method of producing clayware by firing a composition containing clay and a boron-containing flux, characterised in that the flux is a synthetic alkali metal and/or alkaline earth metal aluminosilicate having the crystal structure of a zeolite and containing boron entrapped within that structure.
2. A method according to claim 1, characterised in that the aluminosilicate has been synthesised by hydrothermal crystallisation from a reaction mixture containing a source of alkali metal or alkaline earth metal, a source of silica, a source of alumina and a source of boron.
3. A method according to claim 2, characterised in that the aluminosilicate is in the form of crystals having a particle size below 5 microns.
4. A method according to claim 1, characterised in that the aluminosilicate is a sodium aluminosilicate.
5. A method according to claim 1, characterised in that a composition comprising calcined bone, china clay and the boron-containing flux is fired to produce bone china.
6. A method according to claim 5, characterised in that the composition is fired at a temperature below about 1200°C.
7. A method according to claim 1, characterised in that a composition containing ball clay, china clay, flint and the boron-containing flux, is fired to produce earthenware.
8. The method according to claim 1, 5 or 7, in which said boron-containing aluminosilicate contains about 3 to 7.5 per cent, by weight, B2O3.
9. The method according to claim 1, 5 or 7, in which said boron-containing aluminosilicate contains about 2 to 10 percent, by weight, B2O3.
10. Clayware produced according to the method of claim 1, 4 or 7.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000374926A CA1148982A (en) | 1981-04-08 | 1981-04-08 | Compositions and methods for producing clayware |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000374926A CA1148982A (en) | 1981-04-08 | 1981-04-08 | Compositions and methods for producing clayware |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1148982A true CA1148982A (en) | 1983-06-28 |
Family
ID=4119675
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000374926A Expired CA1148982A (en) | 1981-04-08 | 1981-04-08 | Compositions and methods for producing clayware |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1148982A (en) |
-
1981
- 1981-04-08 CA CA000374926A patent/CA1148982A/en not_active Expired
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