An enamel paste for preparing a raku glaze and a method for preparing a raku glaze

Abstract

The present application discloses a glaze paste for preparing a kiln glaze surface and a preparation method of the kiln glaze surface. The raw materials of the glaze paste include 42 parts of potassium feldspar, 7 parts of Suzhou soil, 5 parts of quartz, 0-8 parts of calcite, 9 parts of zinc oxide, 6.2 parts of titanium white, 25 parts of frit, 7 parts of barium carbonate, 1.4 parts of copper oxide and 2 parts of cobalt oxide 3 . The present application utilizes the principle that titanium has poor opacifying effect when the calcium content is low, and the reaction produces a glaze surface with kiln effect. When the calcium content is moderate, the glaze surface has good gloss; when the calcium content is low, the glaze surface has poor gloss and is even matt or non-luster, and the color changes to black brown; when the calcium content is high, the glaze surface is green. By controlling the fineness of the glaze paste, the glaze surface firing quality is ensured; by controlling the spraying thickness of the glaze layer, the kiln effect of the glaze surface color is ensured. The thermal stability, microwave oven test and lead and cadmium dissolution amount can all meet the standard of daily tableware.

Description

TECHNICAL FIELD

[0001] The present application relates to a kiln glaze, in particular to a glaze slip for preparing the kiln glaze and a preparation method of the kiln glaze, and belongs to the technical field of ceramic production. BACKGROUND

[0002] Glaze is a glassy thin layer attached to the surface of the ceramic body. It is mainly made of clay, flux raw materials, refractory materials, auxiliary materials and other raw materials through weighing, ball milling, glazing and firing at high temperature. It has the advantages of compactness, hardness, gloss, non-water absorption, etc., greatly improves the service life, and improves the decoration of ceramics through rich color changes and special glaze effects.

[0003] The main properties of glaze are:

[0004] 1. Chemical stability, the glaze layer should have certain acid and alkali corrosion resistance, prevent the release of lead, chromium and other heavy metals affecting human health, and aluminum oxide, zinc oxide can improve the alkali resistance of the glaze, and calcium oxide, magnesium oxide and barium oxide can effectively improve the chemical stability of the glaze.

[0005] 2. Hardness of mechanical strength, mechanical strength is an important property of glaze, and the ability of glaze to resist tensile stress is usually many times smaller than the ability to resist compressive stress, so the glaze must be compressed stress without tensile stress, which can be achieved by adjusting the expansion coefficient of the body and the glaze. The hardness of the glaze is also a very important indicator, and generally to improve the scratch hardness, the content of boron oxide can be reduced, and part of potassium oxide can be replaced with lithium oxide, and lead oxide can be replaced with zinc oxide, barium oxide and magnesium oxide.

[0006] 3. Gloss, gloss is also an important property of glaze, and the gloss of glaze is directly related to the refractive index. The greater the refractive index, the stronger the gloss, which can be achieved by reducing the surface tension of the melt and increasing the high-temperature fluidity of the melt.

[0007] Kiln change mainly refers to the uncertainty of the surface glaze color of porcelain caused by the change of the temperature in the kiln during the firing process.

[0008] Through kiln change production, the glaze surface with performance and special color is produced, which is pursued in ceramic production. SUMMARY

[0009] In order to solve the problems of the prior art, the purpose of the present application is to provide a kiln glaze and a preparation method thereof.

[0010] In order to achieve the above-mentioned goal, the technical scheme adopted by the present application is as follows:

[0011] An enamel paste for preparing a kiln glaze, comprising water and raw materials in a mass ratio of 1:1; the raw materials comprise potassium feldspar 42 parts, Suzhou clay 7 parts, quartz 5 parts, calcite 0-8 parts, zinc oxide 9 parts, titanium white 6.2 parts, frit 25 parts, barium carbonate 7 parts, copper oxide 1.4 parts, cobalt oxide 2 parts, by mass fraction;

[0012] The chemical composition of the raw materials is:

[0013]

[0014] The fineness of the enamel paste is up to 250 mesh, and the specific gravity is 1.5-1.6 g / cm 3 .

[0015] The above-mentioned enamel paste is prepared by:

[0016] The raw materials, water and balls are mixed in a mass ratio of 1:1:1.5, and then ball-milled by a ball mill, with a sieve residue of 0.07-0.12%.

[0017] A preparation method of a kiln glaze, wherein the above-mentioned enamel paste is sprayed on a ceramic body, and then fired to obtain the kiln glaze.

[0018] The thickness of the above-mentioned enamel paste sprayed on the ceramic body is 0.5 mm.

[0019] The firing temperature is 1220-1250℃, the high fire holding time is 20-30 minutes, the firing time is 5-6 hours, and the firing cycle is 21 hours.

[0020] The preparation method of the above-mentioned kiln glaze further comprises pre-firing the zinc oxide and titanium white before ball-milling, and the pre-firing temperature is 1220-1250℃.

[0021] When the above-mentioned calcite is 0 part, the kiln glaze is black-brown.

[0022] When the above-mentioned calcite is 4 parts, the kiln glaze is brown.

[0023] When the above-mentioned calcite is 8 parts, the kiln glaze is green.

[0024] The firing temperature of the above-mentioned body is 1200-1250℃, the water absorption rate is 1.5-3.5%, and the chemical composition of the body is:

[0025]

[0026] The present application has the advantages of:

[0027] The invention is a glaze slurry for preparing a kiln glaze surface and a method for preparing the kiln glaze surface. The principle of poor opalescence effect of titanium in the case of less calcium content is used to produce the glaze surface with brown kiln effect at the melting temperature of 1220-1250℃. The kiln color and effect of titanium are adjusted by changing the calcium content. When the calcium content is moderate, the glaze surface has good gloss and strong opalescence effect, and the glaze surface is green. When the calcium content is low, the glaze surface is matt, the opalescence effect is weak, and the glaze surface is brown. When the calcium content is zero, the glaze surface becomes dull and rough, the opalescence effect is very poor, and the glaze surface is black brown. The glaze surface firing quality is ensured by controlling the fineness of the glaze slurry, and the kiln effect of the glaze color is ensured by controlling the spraying thickness of the glaze layer and the kiln reaction.

[0028] The kiln glaze surface and the method for preparing the same can be used in the firing of artistic porcelain, craft porcelain and decorative products, and can also be used in daily tableware. The thermal stability, microwave oven test and lead and cadmium dissolution amount can all meet the standards of daily tableware, and the kiln glaze surface has strong practicability and wide applicability. DETAILED DESCRIPTION

[0029] The invention will be specifically described below in combination with specific examples.

[0030] Example 1

[0031] (1) Preparation of the glaze slurry

[0032] ① Weighing: take 42 parts of feldspar, 7 parts of Suzhou soil, 5 parts of quartz, 4 parts of calcite, 9 parts of zinc oxide, 6.2 parts of titanium white, 25 parts of frit, 7 parts of barium carbonate, 1.4 parts of copper oxide and 2 parts of cobalt oxide as the raw materials of the glaze slurry according to the weight parts.

[0033] Among them, the zinc oxide and titanium white are precalcined before use to remove organic impurities, and the precalcination temperature is 1220-1250℃.

[0034] The structure of the ceramic product is the internal cause of determining its performance and quality, and the structure of the ceramic product is ensured by the types of raw materials and the process production, so the selection of raw materials is particularly important. The chemical composition of the main raw materials selected in the invention is shown in the following table:

[0035] Chemical composition of the glaze raw materials (wt%)

[0036]

[0037] ② Ball milling: according to the ratio of raw materials: ball: water = 1:1.5:1, ball milling is carried out through the ball mill, and after ball milling, sieving is carried out with a 250 mesh sieve, and the sieve residue needs to be kept between 0.07-0.12%, and the specific gravity of the glaze is 1.5-1.6g / cm 3 .

[0038] (2) Glazing

[0039] First, the sponge is used to clean the body, and then the glaze is evenly sprayed on the ceramic body, and the thickness of the glaze layer is controlled to be 0.5mm.

[0040] The body belongs to the stoneware class (firing temperature 1200-1250℃, water absorption 1.5-3.5%), and in order to achieve the strength required by the dishwasher and meet the use of microwave oven, the water absorption of the body must be strictly controlled.

[0041] The chemical composition of the body is shown in the following table:

[0042] The chemical composition of the body

[0043]

[0044] (3) Firing

[0045] The body is fired in a common tunnel kiln, the highest firing temperature is 1230℃, the high fire holding time is 30 minutes, the firing time is 6 hours, and the firing cycle is 21 hours.

[0046] Conclusion: The product prepared by the above process steps has a smooth surface, a brown matte kiln change glaze, a warm touch, and a special artistic effect; the glaze has no glaze bubbles, the pinhole rate is less than 1.5%; the thermal stability is good, and the glaze layer does not crack after 1 time of heat exchange at 20-200℃; the product strength can adapt to the strong impact of the automatic dishwasher; the lead leaching amount of the glaze layer is less than 0.2mg / L (detection limit), the cadmium leaching amount is less than 0.02mg / L (detection limit), and it is safe for the human body.

[0047] Example 2

[0048] Under the condition that the other conditions remain unchanged, the amount of calcite is changed to 8 parts, and the product prepared has a strong glaze gloss compared to the example, and the glaze effect is green and bright.

[0049] Example 3

[0050] Under the condition that the other conditions remain unchanged, the amount of calcite is removed, and the product prepared has a matte and rough glaze compared to the example, and the color changes to black brown.

[0051] Example 4

[0052] Under the condition that the other conditions remain unchanged, the fineness of the glaze is changed to 0.5%, and the product prepared has pinholes and becomes rough compared to the example, and the glaze quality is not good.

[0053] The fineness of the glaze is changed to 0.02%, and the product prepared has glaze shrinkage defects compared to the example.

[0054] Example 5

[0055] If the thickness of the glaze layer is increased, the product produced will have a flow glaze defect compared to the glaze of Example 1.

[0056] If the thickness of the glaze layer is reduced, the product produced will have a weaker kiln effect compared to the glaze of Example 1.

[0057] From the above examples, it can be seen that:

[0058] 1. Influence of raw material components

[0059] The chemical composition of the glaze directly affects the effect of the glaze.

[0060] When the calcium content is moderate, the glaze has good luster and strong opalescence, and the glaze is green.

[0061] When the calcium content is low, the glaze is relatively matte, the opalescence is weak, and the glaze is brown.

[0062] When the calcium content is zero, the glaze becomes dull and very rough, the opalescence is very poor, and the glaze is black-brown.

[0063] 2. Influence of glaze slurry fineness

[0064] Fineness has a great influence on the maturing temperature of the glaze, the high-temperature viscosity of the glaze, the quality of the glaze, and the size of the crystals.

[0065] If the particles of the glaze material are too coarse, the high-temperature viscosity of the glaze material is large, which hinders the discharge of gas, easily forms glaze pinholes or bubbles, and at the same time, the glaze has poor flowability, it is difficult to fill the pits left by the discharge of gas on the glaze surface to form glaze pinholes, and it is not conducive to phase separation and crystallization.

[0066] If the glaze material is too fine, it will cause the glaze to dry slowly and be prone to cracking, and shrinkage defects are easily produced during firing.

[0067] The fineness is controlled to be between 0.07-0.12% of the residue on the 100-mesh screen in the present application, which can ensure the quality of the glaze and prevent the product from sticking to the feet.

[0068] 3. Influence of glaze layer thickness

[0069] The thickness of the glaze layer has a great influence on the effect of the glaze.

[0070] If the glaze layer is too thick, although the kiln reaction of the glaze is strong, flow glaze defects are easily produced;

[0071] If the glaze layer is too thin, although flow glaze defects are not produced, the color of the glaze is shallow and the kiln effect is not obvious.

[0072] The thickness of the glaze layer is related to the specific gravity of the glaze slurry, the time of applying the glaze, and the method of applying the glaze.

[0073] The glaze slurry specific gravity rises, the glaying glaze layer thickness is uneven, is easy to crack, and the glaze layer is too thick and can cause glaze flow and glaze shrinkage.

[0074] The glaze slurry specific gravity drops, and the glazing time needs to be prolonged, and the body strength is relatively high.

[0075] The glaze layer thickness of the present application is 0.5mm, which ensures the kiln effect of glaze color.

[0076] The above shows and describes the basic principles, main features and advantages of the present application. Those skilled in the art should understand that the above examples do not limit the present application in any form, and any technical solution obtained by equivalent replacement or equivalent transformation falls within the protection scope of the present application.

Claims

1. A glaze slurry for preparing kiln-transformed glazes, characterized in that, Includes water and raw materials in a 1:1 mass ratio; By weight, the raw materials include 42 parts potassium feldspar, 7 parts Suzhou clay, 5 parts quartz, 0-8 parts calcite, 9 parts zinc oxide, 6.2 parts titanium dioxide, 25 parts frit, 7 parts barium carbonate, 1.4 parts copper oxide, and 2 parts cobalt oxide. The chemical composition of the raw material, by mass percentage, is as follows: ， The glaze slurry has a fineness of 250 mesh and a specific gravity of 1.5-1.6 g / cm³. 3 ; When the calcite content is 0 parts, the kiln-transformed glaze is dark brown; When the calcite content is 4 parts, the kiln-transformed glaze is brown; When the calcite content is 8 parts, the kiln-transformed glaze is green.

2. The glaze paste according to claim 1, characterized in that, The preparation method is as follows: The raw materials, water, and balls are mixed in a mass ratio of 1:1:1.

5. After ball milling, the residue on the sieve is 0.07-0.12%.

3. A method for preparing a kiln-transformed glaze, characterized in that, The glaze slurry described in claim 1 or 2 is sprayed onto a ceramic bisque body and fired to obtain a kiln-transformed glaze surface.

4. The method for preparing kiln-transformed glaze according to claim 3, characterized in that, The thickness of the glaze slurry sprayed onto the ceramic bisque body is 0.5 mm.

5. The method for preparing kiln-transformed glaze according to claim 3, characterized in that, The firing temperature is 1220-1250℃, the high-temperature holding time is 20-30 minutes, the firing time is 5-6 hours, and the firing cycle is 21 hours.

6. The method for preparing kiln-transformed glaze according to claim 3, characterized in that, It also includes pre-calcining zinc oxide and titanium dioxide before ball milling, with a pre-calcination temperature of 1220-1250℃.

7. The method for preparing kiln-transformed glaze according to claim 3, characterized in that, The bisque firing temperature of the green body is 1200-1250℃, the water absorption rate is 1.5-3.5%, and the chemical composition of the green body is as follows: 。

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