Bone china high-glossiness dark black glaze, ceramic product with glaze and preparation method of ceramic product

Abstract

The invention provides bone china high-glossiness dark black glaze, a ceramic product with the glaze and a preparation method, and belongs to the technical field of ceramic production, the dark black glaze comprises the following raw materials: low-zinc frit, Longyan clay, zirconium silicate, cobalt melanin and organic rubber powder; the ceramic product comprises a green body and dark black glaze covering the surface of the green body, the preparation method comprises the following steps: preparing glaze slip, glazing and sintering, the black ground glaze adopts low-zinc basic fritted glaze with a lower melting point and relatively stable cobalt melanin, cobalt in the melanin is inhibited from emitting blue color, cobalt is weakened to be blue, and the glaze surface is controlled to float blue, so that deeper black color is shown, and the dark black ground glaze is provided; the transparent cover glaze adopts high-brightness medium-low-temperature zinc-free fritted glaze, the two layers of glaze surfaces do not react and interfere with each other and complement each other, a bright black glaze surface is finally formed, and waste glaze generated during glazing can be recycled after being processed, so that the efficiency is improved, the cost is reduced, energy is saved, emission is reduced, and environmental pollution is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of ceramic production, and is a bone china glaze surface and a preparation method thereof, specifically relating to a high-gloss deep black glaze for bone china, a ceramic product with such a glaze, and a preparation method thereof. Background Art

[0002] The original bone ash bone china adopts a two-fire process, namely high-temperature biscuit firing and low-temperature glaze firing. The high-temperature biscuit firing temperature is generally controlled at 1250°C - 1260°C; the low-temperature glaze firing temperature is controlled at 1130°C - 1150°C. For general products, the biscuit firing time is controlled at about 9 - 11 hours, among which the heat preservation time is 40 - 60 minutes; the glaze firing time is controlled at about 8 - 9 hours, and the heat preservation time is 30 - 60 minutes. If there are special or irregular-shaped products, the firing time should be adjusted appropriately according to the product specifications and structures. The raw materials used in bone china are different from other porcelain types, so its shrinkage rate is large (about 15% - 18%); the firing range is narrow (about 3°C - 6°C). Therefore, in actual production, the process should be strictly controlled, and key factors such as people, machines, materials, methods, and the environment should be strictly controlled, and it cannot be done simply.

[0003] With the rapid development of the economy, people's living standards have been continuously improved. The trend of pursuing thinner, better-performing, and highly decorative ceramic products has become more and more popular, and the existing decorative effects can no longer meet people's aesthetic needs. At the same time, for the bright black bone china glaze surface, due to process technical problems such as high difficulty in achieving black color, low specular reflection, and easy blue floating on the glaze surface, the yield of genuine products is low and the cost is relatively high; moreover, the difficulty of recovering the glaze water is large, which pollutes the environment to a certain extent. Summary of the Invention

[0004] Object of the Invention: The object of the present invention is to provide a high-gloss deep black glaze for bone china, a ceramic product with such a glaze, and a preparation method thereof, aiming at the deficiencies of the existing technology, to enhance the yield of genuine products of the bright black glaze surface of bone china, and at the same time establish a recycling and reuse system for black glaze, reduce environmental pollution; save energy, reduce emissions, increase efficiency, and reduce costs.

[0005] Technical Solution: The high-gloss deep black glaze for bone china described in the present invention includes water and raw materials. By weight, the raw materials include 75 parts of low-zinc frit, 1 part of Longyan clay, 1 part of zirconium silicate, 20 parts of cobalt black pigment, and 2 parts of organic glue powder.

[0006] The structure of a ceramic product is the internal factor determining its performance and quality, and the structure of a ceramic product is ensured by the types of raw materials and the process production process. Therefore, the selection of raw materials is particularly important. The chemical compositions of the main raw materials selected in the present invention are as follows:

[0007]

[0008] The water content of the high-gloss deep black glaze is 45%, and the specific gravity ranges from 1.55 to 1.58 g / cm 3 .

[0009] The present invention also provides a ceramic product, including a green body and a glaze layer covering the surface of the green body, and the glaze layer is the above-mentioned high-gloss deep black glaze.

[0010] The present invention also provides a preparation method of the ceramic product as above, including the following steps:

[0011] Step 1, preparing glaze slurry

[0012] 1.1, weighing by mass ratio, 75 parts of low-zinc frit, 1 part of Longyan clay, 1 part of zirconium silicate, 20 parts of cobalt black pigment, and 2 parts of organic rubber powder as raw materials for the deep black glaze slurry;

[0013] 1.2, ball-milling the low-zinc frit alone. After mixing the other raw materials except the low-zinc frit, a mixture is obtained and ball-milled. During ball-milling, the mass ratio of the mixture, balls, and water is: 1:1.5:1; then the mixture and the separately ball-milled low-zinc frit are stirred and mixed;

[0014] 1.3, after ball-milling, perform a primary sieving with a 250-mesh vibrating sieve without removing iron. The sieve residue is passed through 325 meshes and kept between 0.01% and 0.1% to obtain the glaze slurry. Adjust the water content of the glaze slurry to 45%, and the specific gravity ranges from 1.55 to 1.58 g / cm 3 ;

[0015] Step 2, glazing

[0016] 2.1, prepare a bone china biscuit body. After passing the inspection, perform grinding, polishing, and drying. Before spraying the glaze, use an air gun to blow off the floating dust on the surface of the body;

[0017] 2.2, evenly spray the glaze slurry obtained in Step 1 on the bone china biscuit body, spray the black base glaze: the base glaze layer is relatively thin, control the spraying thickness to be 0.06 mm, not greater than 0.1 mm. After glaze firing, the thickness of the base glaze is not greater than 0.08 mm. After firing, the glaze surface is in a semi-matte state, the surface is flat and smooth, and the viscosity of the glaze is relatively large at high temperature, with a certain surface tension. At this time, the bone china biscuit body has a black-colored body;

[0018] The waste generated after spraying the deep black glaze can be recycled: the waste glaze material generated during spraying, after independent recovery, this dry powder is added with water and ball-milled for 2 h, and passed through a 250-mesh vibrating sieve twice without removing iron; the sieve residue is passed through 325 meshes and kept between 0.01% and 0.1%; the water content is about 45%, and the specific gravity is 1.55 - 1.58 g / cm 3 . After testing, it can be used alone again.

[0019] 2.3. After the base glaze is fired, spray the transparent glaze evenly on the black color blank after firing. Control the thickness of the glaze layer to be medium, control the spraying glaze thickness to 0.1mm, and not more than 0.15mm. The thickness of the base glaze after glaze firing is not more than 0.12mm. After firing, the glaze surface is bright and smooth, with a glassy texture. The fluidity of the glaze is average, and the high-temperature viscosity is small. The raw material of the transparent glaze is a medium-low temperature zinc-free transparent frit, and the chemical composition is shown in the following table:

[0020]

[0021] Step 3: Firing

[0022] The firing is carried out in an oxidizing atmosphere in a tunnel kiln, with the maximum firing temperature ranging from 1130°C to 1150°C, high fire insulation for 60 minutes, firing time of 8 to 9 hours, and a firing cycle of about 21 hours.

[0023] Furthermore, cobalt melanin must be pre-calcined at high temperature before use: to make the metal pigment and mineralizer combine more tightly, the color is more stable, so that the black base glaze is easier to melt, the glaze surface is smoother, and it is not easy to have bald glaze, pinholes and lumps. The pre-calcination temperature is 1250℃-1260℃. The pre-calcination time is about 23 hours for the firing cycle, and the maximum temperature is 1260℃, which is kept warm for 45 minutes.

[0024] Further, in step 1.2, the low-zinc frit is separately ball-milled as follows: during ball milling, the mass ratio of the low-zinc frit, the ball and the water is 1:1.5:1, and after ball milling, a low-zinc frit glaze is obtained, and the low-zinc frit glaze is dilute and can be precipitated, so that the specific gravity of the low-zinc frit glaze is in the range of 1.73-1.74 g / cm 3 The residue on the sieve is passed through a 325-mesh sieve and maintained between 0.2% and 0.5%; the moisture content is 28% to 32%, and the iron is removed by an electromagnet and passed through a 200-mesh vibrating screen once.

[0025] Furthermore, in step 1.3, the ball milling is specifically as follows: after mixing the low-zinc frit glaze, Longyan soil, zirconium silicate and pre-calcined cobalt black pigment, water is added, and depending on the total amount of ball milling and the amount of water added, the two are first ball milled together for 16h-20h; then, because it is necessary to increase the suspension stability and adhesion of the glaze and ensure that the organic rubber powder is not ineffective due to excessive ball milling, the organic rubber powder is added last and ball milled for 3-4h.

[0026] Furthermore, the firing temperature of the bone china biscuit body is 1250°C - 1260°C, the water absorption rate ≤ 0.5%, and the tricalcium phosphate content ≥ 36%. In order to make the bone china thin, light, and convenient to use, and not crack after being heated to 140°C and then put into 20°C water for one heat exchange, the quality of the biscuit body needs to be strictly controlled: the biscuit body should have a certain thickness, but not too thick, depending on the product and the shape part, about 2.3mm - 3.2mm. The chemical composition of the bone china biscuit body is:

[0027]

[0028] Beneficial effects: Compared with the prior art, the advantages of the present invention are as follows:

[0029] A high-temperature biscuit body of bone china is fired at 1250°C - 1260°C. First, a thin layer of black semi-matte base glaze is applied, and after being fired and carbonized at 1130°C in an electric kiln furnace, the black semi-matte base glaze does not undergo any kiln change reaction with the bone china biscuit body; then, a layer of high-brightness transparent glaze is applied, and after being fired at 1130°C - 1150°C, finally, a bone china decorative glaze surface with high glaze surface brightness, deep blackness, controllable blue floating, and good thermal stability is formed.

[0030] The black base glaze uses a low-zinc base frit glaze with a relatively low melting point and a relatively stable cobalt black pigment. When a little zinc is used during high-temperature roasting, it will promote the cobalt to emit a green tone, inhibit the cobalt in the black pigment from emitting a blue tone, weaken the cobalt from showing blue, control the blue floating on the glaze surface, and thus show a deeper black tone, providing a deep black base glaze; while the transparent top glaze uses a high-brightness medium and low-temperature zinc-free frit glaze to provide a high-brightness and glassy texture outer glaze surface; the two layers of glaze surfaces do not react or interfere with each other, making up for each other's deficiencies, and finally forming a bright black glaze surface. Moreover, the waste glaze generated during glazing can be recycled after processing, thereby improving efficiency, reducing costs, saving energy and reducing emissions, and avoiding environmental pollution.

[0031] The dissolution amounts of lead and cadmium in the product are not detected. The blackness and brightness of the glaze surface are very high, and it has strong decoration and practicability, and is widely used.

[0032] The bone china products made according to the bone china black glaze surface and its preparation method of the present invention have very high blackness and brightness of the glaze surface, strong decoration and practicability, and can be applied to art porcelain, craft porcelain, and high-end wine bottles and wine utensils, and can also be widely applied to daily-use tableware. The thermal stability, microwave oven test, and lead and cadmium dissolution amounts of the products can all meet the standards of daily-use tableware, and it has strong practicability and wide applicability. Description of the Drawings

[0033] Figure 1 It is the process flow chart of the present invention. Detailed Embodiments

[0034] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings, but the protection scope of the present invention is not limited to the described embodiments.

[0035] Example 1

[0036] As Figure 1 shown, a high-gloss deep black glaze for bone china, by weight, the raw materials include 75 parts of low-zinc frit, 1 part of Longyan clay, 1 part of zirconium silicate, 20 parts of cobalt black pigment, and 2 parts of organic rubber powder.

[0037] Chemical composition of raw materials for glaze (wt%)

[0038]

[0039] The water content of the high-gloss deep black glaze is 45%, and the specific gravity range is 1.55 - 1.58 g / cm 3 .

[0040] Example 2

[0041] A ceramic product, including a body and a glaze layer covering the surface of the body, and the glaze layer is the high-gloss deep black glaze of Example 1.

[0042] Example 3

[0043] A method for preparing a ceramic product, characterized by comprising the following steps:

[0044] Step 1, preparing glaze slurry

[0045] 1.1, weighing by mass ratio, 4480 g of low-zinc frit glaze water, 40 g of Longyan clay, 40 g of zirconium silicate, 800 g of cobalt black pigment, 80 g of organic rubber powder, and 1800 g of water as the raw materials for the deep black glaze slurry; the cobalt black pigment is pre-calcined at high temperature before use, the pre-calcination temperature is 1250°C - 1260°C, and the pre-calcination time: the firing cycle is about 23 hours, and the highest temperature is held for 45 minutes.

[0046] 1.2, separately ball-milling the low-zinc frit, mixing the other raw materials except the low-zinc frit to obtain a mixture, and then ball-milling it. When ball-milling, the mass ratio of the mixture, balls, and water is: 1:1.5:1; then the mixture and the separately ball-milled low-zinc frit are stirred and mixed; specifically, separately ball-milling the low-zinc frit means:

[0047] When ball-milling, the mass ratio of the low-zinc frit, balls, and water is ball-milled according to the ratio of 1:1.5:1. After ball-milling, low-zinc frit glaze water is obtained. The low-zinc frit glaze water is relatively dilute and can precipitate, so that the specific gravity range of the low-zinc frit glaze water is 1.73 - 1.74 g / cm 3The residue on the sieve is 325 mesh, maintained between 0.2% and 0.5%; the moisture content is 28% to 32%, the electromagnet removes iron, and passes through a 200 mesh vibrating screen once. The low zinc frit corresponds to about 4480g of glaze water with a specific gravity of 1.73.

[0048] During ball milling, the mass ratio of the medium-low temperature zinc-free transparent frit, ball and water is 1:1.5:1. After ball milling, the medium-low temperature zinc-free transparent frit glaze is dilute and can be precipitated, making the medium-low temperature zinc-free transparent frit glaze specific gravity 1.73-1.74g / cm 3 The fineness is 0.01%-0.1% after passing through a 325-mesh sieve; the moisture content is 28%-32%, and the iron is removed by an electromagnet. It can be used after passing through a 200-mesh vibrating screen once.

[0049] 1.3. After ball milling, sieve once with a 250-mesh vibrating screen without removing iron. The residue is 325 mesh and maintained between 0.01% and 0.1% to obtain glaze slurry. The water content of the glaze slurry is adjusted to 45% and the specific gravity range is 1.55-1.58g / cm 3 ; The specific process of ball milling is as follows: after mixing the low-zinc frit glaze, Longyan soil, zirconium silicate and pre-calcined cobalt black pigment, add water, and ball mill them together for 16h-20h according to the total amount of ball milling and the amount of water added; then, because it is necessary to increase the suspension stability and adhesion of the glaze and ensure that the organic rubber powder is not ineffective due to excessive ball milling, the organic rubber powder is added last and ball milled for 3-4h.

[0050] Step 2: Glazing

[0051] 2.1. Prepare bone china bisque body. The firing temperature of bone china bisque body is 1250℃-1260℃, the water absorption rate is ≤0.5%, and the tricalcium phosphate content is ≥36%. In order to make the bone china light and thin, easy to use, and not crack after being heated to 140℃ and put into 20℃ water for heat exchange once, the quality of the bisque body needs to be strictly controlled: the bisque body should have a certain thickness, but not too thick, depending on the product and the shape of the part, about 2.3mm-3.2mm.

[0052] The chemical composition of the bone china bisque fired body is:

[0053]

[0054] After passing the inspection, the blank is ground, polished and dried. Before spraying glaze, the dust on the surface of the blank is blown away with a spray gun.

[0055] 2.2. Spraying black underglaze: Evenly spray the black glaze slurry onto the bisque-fired bone china body. The underglaze layer is relatively thin, controlling the spraying thickness at 0.06 mm, not exceeding 0.1 mm. After glaze firing, the thickness of the underglaze does not exceed 0.08 mm. After firing, the glaze surface is in a semi-matte state, smooth and flat. The viscosity of the glaze is relatively large at high temperatures and has a certain surface tension. At this time, the bisque-fired bone china body has a black-colored body.

[0056] 2.3. After the underglaze is fired, spray the transparent surface glaze: Evenly spray the transparent surface glaze onto the black-colored body after color baking. The glaze layer has a medium thickness, controlling the spraying thickness at 0.1 mm, not exceeding 0.15 mm. After glaze firing, the thickness does not exceed 0.12 mm. After firing, the glaze surface is bright, smooth, with a glassy texture. The fluidity of the glaze is average, and the viscosity at high temperatures is relatively small.

[0057] Step 3. Firing

[0058] Fire using an oxidation atmosphere in a tunnel kiln. The maximum firing temperature range is 1130°C - 1150°C, hold at high fire for 60 minutes, the firing time is 8 - 9 hours, and the firing cycle is about 21 hours to obtain the product.

[0059] Conclusion: The product obtained through the above technological steps has a smooth surface, a glassy texture, a deep black glaze surface without blue tones floating, a warm and delicate touch, and strong decorativeness; there are no glaze bubbles on the glaze surface, and the pinhole rate is less than 1.5%; it has good thermal stability, and the glaze layer does not crack after 1 heat exchange at 20 - 200°C; the water absorption rate ≤ 0.5%, and the tricalcium phosphate content ≥ 36%; the lead and cadmium dissolution amount of the glaze layer is lower than the national standard, ensuring safety for the human body.

[0060] The following are comparative examples by changing certain conditions of the examples.

[0061] Comparative Example 1: Without changing other conditions, change the low-zinc frit in the black underglaze to a zinc-free medium-high temperature frit. The product obtained has an unfired matte glaze surface compared to the example, shows a blue tone after color baking, and is applied with a medium-low temperature transparent surface glaze. After glaze firing, the blue floating phenomenon is very serious. Therefore, only low-zinc frit can be used for the black underglaze.

[0062] Comparative Example 2: Without changing other conditions, use the cobalt black pigment in the black underglaze directly without calcination. Then, the more pointed parts of the fired product are mostly gray-black, there is a risk of glaze peeling, and the black glaze coverage is uneven. Therefore, the cobalt black pigment in the black underglaze needs to be calcined at 1250 - 1260°C.

[0063] Comparative Example 3: Without changing other conditions, increase the glaze firing thickness of the black underglaze to about 0.15 mm - 0.2 mm. The glaze layer is relatively thick, and a medium-low temperature transparent surface glaze is normally applied. After glaze firing, the blue floating phenomenon is very serious. Therefore, the glaze layer thickness of the black underglaze needs to be strictly controlled and be relatively thin.

[0064] Comparative Example 4: When other conditions remain unchanged and the addition amount of the organic rubber powder is reduced, the black underglaze is extremely likely to precipitate. During glaze spraying, the granularity is relatively heavy, and color spots are likely to appear on the glaze surface.

[0065] Comparative Example 5: When other conditions remain unchanged and the medium and low temperature transparent surface glaze is changed to a medium temperature transparent surface glaze, after glaze firing, there is no obvious change in the blackness and brightness of the product, and the phenomenon of blue floating does not appear on the glaze surface.

[0066] Comparative Example 6: When other conditions remain unchanged and the milling time of the recycled material of the black glaze is prolonged, the product is prone to the risk of glaze shrinkage; when the milling time of the black glaze is shortened or the sieving times are reduced, obvious granularity will appear during glaze spraying.

[0067] Through the above comparative examples, the following conclusions can be drawn:

[0068] 1. Influence of raw material components:

[0069] The chemical composition of the glaze directly affects the effect of the glaze surface. The black underglaze uses a low-zinc base frit glaze with a relatively low melting point and a relatively stable cobalt black pigment. When a little zinc is used during high-temperature color baking, it will promote the cobalt to emit a green tone, inhibit the cobalt in the black pigment from emitting a blue tone, weaken the cobalt from showing blue, control the blue floating on the glaze surface, and thus show a deeper black tone, providing a deep black underglaze; zinc element is indispensable. And the black pigment needs to be calcined at high temperature, and its coloring ability is greatly improved.

[0070] The transparent surface glaze uses a medium and low temperature zinc-free frit glaze with high brightness to provide a high-brightness and glassy-textured outer glaze surface; the two layers of glaze surfaces do not react or interfere with each other, learn from each other's strengths and make up for each other's weaknesses, and finally form a high-gloss deep black glaze surface.

[0071] 2. Influence of glaze slurry fineness:

[0072] The fineness has a great influence on the maturity temperature, high-temperature viscosity, glaze surface quality and crystal size of the glaze.

[0073] If the glaze particles are too coarse, it will cause the high-temperature viscosity of the glaze to be large, hinder the discharge of gas, and easily form pinholes or bubbles on the glaze surface. At the same time, the fluidity of the glaze surface is also poor, and it is difficult to fill the pits left on the glaze surface when the gas is discharged to form pinholes on the glaze surface, and it is not conducive to phase separation crystallization; if the glaze is too fine, it will cause the glaze surface to dry slowly and be prone to cracking, and shrinkage glaze defects are likely to occur during firing.

[0074] In the present invention, the fineness is controlled to be passed through 325 meshes and maintained between 0.01% and 0.1%. It can not only ensure the glaze surface quality, but also ensure that the product does not shrink glaze and crack.

[0075] 3. Influence of glaze layer thickness:

[0076] The thickness of the glaze layer has a great influence on the effect of the glaze surface. If the glaze layer is too thick, the black glaze surface will show a blue tone, appear grayish blue and white, not black enough, and there is a risk of glaze shrinkage on the glaze surface. If the glaze layer is too thin, the glaze layer on the product surface is likely to be uneven, with mottled color spots, and the operation of repeated glaze replenishment is required, increasing the labor cost and wasting the glaze firing position in the kiln.

[0077] The thickness of the glaze layer is related to the specific gravity of the glaze slurry, the spraying time of the glaze, and the proficiency of the glaze spraying worker. After fixing the specific gravity of the glaze slurry, the requirements for the operation method of the worker are relatively high.

[0078] The thickness of the black underglaze layer of the present invention is 0.06 mm for the sprayed glaze thickness, not greater than 0.1 mm, and the thickness of the underglaze after glaze firing is not greater than 0.08 mm, ensuring the color effect of the black glaze surface; spraying a transparent glaze surface glaze, with a medium glaze layer thickness, controlling the sprayed glaze thickness at 0.1 mm, not greater than 0.15 mm, and the thickness after glaze firing is not greater than 0.12 mm, the glaze surface is bright, smooth, and has a glass texture. The total glaze layer thickness within 0.15 mm - 0.22 mm is a reasonable range.

[0079] As described above, although the present invention has been shown and described with reference to specific preferred embodiments, it should not be construed as a limitation of the present invention itself. Various changes can be made in its form and details without departing from the spirit and scope of the present invention defined by the appended claims.

Claims

1. A bone china high gloss dark black glaze, characterized by: The invention comprises water and raw materials, wherein the raw materials comprise 75 parts of low-zinc frit, 1 part of longyan soil, 1 part of zirconium silicate, 20 parts of cobalt black pigment and 2 parts of organic rubber powder in parts by weight.

2. The bone china high gloss dark black glaze according to claim 1, characterized in that: The chemical composition of the raw materials is: The high gloss dark black glaze has a water content of 45% and a specific gravity range of 1.55-1.58 g / cm 3 .

3. A ceramic product, characterized in that: The invention comprises a body and a glaze layer covering the surface of the body, wherein the glaze layer is the high-gloss dark black glaze as claimed in any one of claims 1 to 2.

4. A method for preparing a ceramic product as claimed in claim 3, characterized in that The steps include: Step 1: Prepare glaze slurry 1.

1. Weigh 75 parts of low-zinc frit, 1 part of Longyan soil, 1 part of zirconium silicate, 20 parts of cobalt black pigment, and 2 parts of organic glue powder as raw materials for dark black glaze slurry according to mass ratio; 1.

2. Ball-mill the low-zinc frit separately, mix the other raw materials except the low-zinc frit, obtain a mixture, and ball-mill it. During the ball-milling, the mass ratio of the mixture, the ball and the water is 1:1.5:1; then stir and mix the mixture and the low-zinc frit after the separate ball-milling; 1.

3. After ball milling, sieve once with a 250-mesh vibrating screen without removing iron. The residue is 325 mesh and maintained between 0.01% and 0.1% to obtain glaze slurry. The water content of the glaze slurry is adjusted to 45% and the specific gravity range is 1.55-1.58g / cm 3 ; Step 2: Glazing 2.

1. Prepare the bone china unglazed body, grind, polish and dry it after it passes the inspection. Use a spray gun to blow away the dust on the surface of the body before spraying glaze; 2.2, spray the glaze slurry obtained in step 1 evenly on the bone china unglazed body to form a base glaze, control the spray glaze thickness to be no more than 0.1mm, and the base glaze thickness after glaze firing to be no more than 0.08mm; at this time, the bone china unglazed body has a black color; 2.

3. After the base glaze is fired, spray the transparent glaze evenly on the fired black base glaze color blank. The thickness of the transparent glaze is in the range of 0.1mm to 0.15mm. The raw material of the transparent glaze is a medium-low temperature zinc-free transparent frit. Step 3: Firing The firing is carried out in an oxidizing atmosphere in a tunnel kiln, with the maximum firing temperature ranging from 1130°C to 1150°C, high fire insulation for 60 minutes, firing time of 8 to 9 hours, and a firing cycle of about 21 hours.

5. The method for preparing a ceramic product according to claim 4, characterized in that: The cobalt melanin is pre-calcined at high temperature before use, the pre-calcination temperature is 1250° C.-1260° C., the pre-calcination period is 23 hours, and the highest temperature is kept for 45 minutes.

6. The method for preparing a ceramic product according to claim 4, characterized in that: In step 1.2, the low zinc frit is ball-milled separately as follows: during ball milling, the mass ratio of the low zinc frit, the ball and the water is 1:1.5:1, and after ball milling, the low zinc frit glaze is obtained. The low zinc frit glaze is dilute and can be precipitated, so that the specific gravity of the low zinc frit glaze is in the range of 1.73-1.74 g / cm 3 The residue on the sieve is passed through a 325-mesh sieve and maintained between 0.2% and 0.5%; the moisture content is 28% to 32%, and the iron is removed by an electromagnet and passed through a 200-mesh vibrating screen once.

7. The method for preparing a ceramic product according to claim 4, characterized in that: In step 1.3, the ball milling is specifically as follows: after mixing the low-zinc frit glaze, Longyan soil, zirconium silicate and pre-calcined cobalt black pigment, add water, and ball mill them together for 16h-20h according to the total amount of ball milling and the amount of water added; then, because it is necessary to increase the suspension stability and adhesion of the glaze and ensure that the organic rubber powder is not ineffective due to excessive ball milling, the organic rubber powder is added last and ball milled for 3-4h.

8. The method for preparing a ceramic product according to claim 4, characterized in that: The sintering temperature of the bone china bisque body is 1250°C-1260°C, the water absorption rate is ≤0.5%, the tricalcium phosphate content is ≥36%, and the chemical composition of the bone china bisque body is:

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