CN111056818B

CN111056818B - High-transparency polished ceramic thick plate and preparation method thereof

Info

Publication number: CN111056818B
Application number: CN201911215635.2A
Authority: CN
Inventors: 谢志军; 欧阳成; 黄玲艳; 卢海鹏; 黄秋立; 肖伟荣
Original assignee: Monalisa Group Co Ltd
Current assignee: Monalisa Group Co Ltd
Priority date: 2019-12-02
Filing date: 2019-12-02
Publication date: 2022-04-12
Anticipated expiration: 2039-12-02
Also published as: CN111056818A

Abstract

The invention discloses a high-transparency polished ceramic thick plate and a preparation method thereof. The preparation method of the high-transparency polished ceramic thick plate comprises the following steps: preparing a high-strength through-body ceramic thick plate blank by using blank powder, wherein the strength of the blank is 2.8-3.5 MPa; spreading overglaze on the blank body, wherein the overglaze application amount is 520-580g/m²(ii) a Applying high-transparency dry granular glaze, wherein the glazing amount of the dry granular glaze is 800-850 g/m²(ii) a Firing at 1200-1290 ℃ for 75-180 min; and manufacturing the large-size ceramic thick plate.

Description

High-transparency polished ceramic thick plate and preparation method thereof

Technical Field

The invention relates to a high-transparency polished ceramic thick plate and a preparation method thereof, belonging to the technical field of ceramic tile production and manufacturing.

Background

With the increase of the specifications of ceramic products, when the strength of a blank is low, the blank is easy to break in the processes of forming, conveying and the like. The invention aims to develop a novel ceramic thick plate which is different from the traditional large plate, can be drilled, polished and cut more conveniently, is suitable for being made into various shapes, is positioned in the application products of the high-end household field, can meet the flexible application in different occasions, and provides great requirements on the blank body, the strength, the random cutting, the surface effect and the product design of the ceramic tile.

Disclosure of Invention

In order to solve the problems, the invention provides a high-transparency polished ceramic thick plate and a preparation method thereof.

In a first aspect, the present invention provides a method for preparing a high-transparency polished ceramic thick plate, comprising the steps of:

preparing a high-strength through-body ceramic thick plate blank by using blank powder, wherein the dry blank strength of the blank is 2.8-3.5 MPa;

spreading overglaze on the blank body, wherein the overglaze application amount is 520-580g/m²；

Applying high-transparency dry granular glaze, wherein the glazing amount of the dry granular glaze is 800-850 g/m²；

Sintering at the temperature of 1200-1290 ℃ for 75-180 min;

and manufacturing the large-size ceramic rock plate.

As the size of ceramic products increases, higher demands are made on the strength of the product blank in order to avoid breakage during the entire production process of the product. When the strength of the green body is low, breakage is easily caused in the forming, conveying and the like processes. Because the ceramic plate has larger specification, the strength of the blank body is attenuated along with the increase of the glazing amount. The damage can be reduced by controlling the glazing amount of the overglaze and the dry particle soft glaze; however, the color development of the product is influenced by the too small glazing amount. The damage rate can be controlled within 2 percent by controlling the strength of the blank body before the high-wear-resistant antifouling ceramic rock plate enters the kiln.

Preferably, the chemical composition of the green body powder comprises: by mass percentage, loss on ignition is 4.7-5.0%, SiO₂57.5-58.5％，Al₂O₃ 27.8-30％，Fe₂O₃ 0.75-1.0％，TiO₂ 0.58-0.66％，CaO 0.35-0.42％，MgO 1.1-1.2％，K₂O 2.1-2.4％，Na₂O 2.5-2.7％。

Preferably, the grain composition of the green body powder comprises: 8-18% above 30 meshes, 30-60 meshes: 70-80%, 60-80 mesh: 6-15% and less than 6% below 80 meshes.

Preferably, the content of aluminum oxide in the overglaze is 29.5-30.5%.

Preferably, the chemical composition of the overglaze comprises: in mass percent, IL (ignition loss) is 4-5%, and SiO₂ 50.7～51.5％，Al₂O₃ 29.0～30.5％，Fe₂O₃ 0.2～0.3％，CaO 0.35～0.50％，MgO 0.1～0.2％，K₂O 5.5～6.5％，Na₂O2.0～2.5％，ZrO₂ 5.9～6.5％。

Preferably, the chemical composition of the high-transparency dry-particle glaze is as follows: 0.45-0.55% loss on ignition, SiO₂ 63～64％，Al₂O₃ 8.5～9.0％，CaO 9.5～10.5％，MgO 0.3～0.4％，BaO 1.0～1.2％，K₂O6.5～7.0％，Na₂O 1.0～1.2％，ZnO9.2～9.8％。

Preferably, the initial melting point of the high-transparency dry particle glaze is 760-790 ℃.

Preferably, the grain composition of the high-transparency dry grain glaze is as follows: 30-32% of 60-80 meshes, 15-18% of 80-100 meshes, 22-25% of 100-120 meshes, 30-32% of 120-250 meshes, and less than 1% below 250.

Preferably, after the overglaze is applied, the green body is subjected to ink-jet printing, and then the high-transparency dry-grain glaze is applied on the ink-jet printed green body.

Preferably, the dielectric glaze is applied on the blank after the ink-jet printing, and then the high-transparency dry-particle glaze is applied.

Preferably, the chemical composition of the dielectric glaze is as follows: loss on ignition of 5.0-5.5%, SiO₂ 55～57％，Al₂O₃ 17～18％，Fe₂O₃ 0.1～0.2％，TiO₂0.1～0.2％，CaO 6.5～7.0％，MgO 2.0～2.3％，K₂O 3.3～3.6％，Na₂O 2.8～3.0％，ZnO3.7～4.0％，BaO 1.5～1.8％。

Preferably, the glazing amount of the dielectric glaze is 40-50 g/m²。

In a second aspect, the present invention also provides a high-transparency polished ceramic slab obtained by any one of the above-mentioned preparation methods. The specification of the high-transparency polished ceramic thick plate is 760-1600 mm multiplied by 1800-3600 mm multiplied by 5.5-20.5 mm in large size. The method of the invention can prepare series ceramic thick plate products with various specifications, such as 1600mm multiplied by 3600mm multiplied by 15.5mm, 1200mm multiplied by 2400mm multiplied by 13.5mm, 1200mm multiplied by 2400mm multiplied by 5.5mm, 760mm multiplied by 2550mm multiplied by 13.5mm, 900mm multiplied by 1800mm multiplied by 10.5mm, 900mm multiplied by 1800mm multiplied by 5.5mm and the like with the surface area of 5.76 square meters.

The high-transparency polished dry-particle ceramic thick plate disclosed by the invention has the characteristics that the high-transparency polished dry-particle ceramic thick plate integrates the advantages of an antique product and a polished product, the glaze is smooth and bright like a polished brick, the pattern is rich like an antique brick, the color is thick and heavy, the ceramic thick plate is gorgeous, the texture is glittering and translucent, and the ceramic thick plate is fine and smooth like jade.

Drawings

Fig. 1 is a flow chart of the preparation process of the microcrystalline decorative ceramic slab with high wear resistance and antifouling property according to an embodiment of the invention.

FIG. 2 is an XRD pattern of samples of different alumina contents.

FIG. 3 is an XRD pattern of calcined bauxite.

Figure 4 is an XRD pattern of samples of different firing cycles.

FIG. 5 is an SEM photograph of samples for different firing cycles.

Fig. 6 is a green body recipe sintering temperature range.

FIG. 7 is a comparison diagram of green body powder and general ceramic body powder magnified 50 times according to one embodiment of the present invention, wherein (a) is green body powder according to the present invention, and (b) is general ceramic body powder.

FIG. 8 is a schematic representation of the fines and hopper walls after dry blending.

FIG. 9 is a color cake diagram of wet ball milling color mixing and dry ball milling color mixing, wherein the first row is wet ball milling color mixing and the second row is dry ball milling color mixing.

FIG. 10 is a graph showing the relationship between the powder breakage rate after dry blending at 20 rpm with the dry blending time, in which 1kg of a coloring material and 250kg of a base material are mixed.

FIG. 11 is a graph showing the relationship between the powder breakage rate after dry blending for 10 minutes using 1kg of a colorant and 250kg of a base material, and the dry blending speed.

FIG. 12 is a side view and a front view of a full body ceramic slab, wherein (a) is a side view of the ceramic slab and (b) is a front view of the ceramic slab.

FIG. 13 is a diagram showing the state of bubbles in the underglaze layers for 4 different sets of dry grain size distributions.

FIG. 14 is a photograph of the highly transparent dry-grained glaze of the present invention and a conventional glazed surface at 50 times magnification by an optical microscope, wherein (a) is a photograph of the dry-grained glazed surface of the present invention at 50 times magnification, and (b) is a photograph of the conventional glazed surface at 50 times magnification.

FIG. 15 is a graph showing the effect of the brick surface of the high-transparency polished ceramic slab according to the embodiment of the present invention.

Fig. 16 is a graph of the effect of cratering caused by direct spreading of frit dry particles after ink jet printing.

Fig. 17 is a graph showing the effect of glaze reduction caused by directly spreading dry frit particles after ink-jet printing.

Detailed Description

The present invention is further illustrated by the following examples, which are to be understood as merely illustrative and not restrictive. The following percentages are by mass unless otherwise specified.

The following description will be made with reference to FIG. 1 for a method of manufacturing a high-transparency polished ceramic slab.

First, green body powder is prepared.

One of the technical problems to be solved in the process of preparing the thick ceramic plate is that the strength of a blank body and the bending of the blank body are not deformed. Among the factors that affect strength are the amount of glass phase, porosity, amount of crystals, and the like. As the number of crystals increases, the number of grain boundaries between the crystals increases, and the crack deflects across the grain boundaries, consuming more energy, resulting in increased failure strength. According to the invention, the test proves that the content of the aluminum oxide in the formula is improved, and the content of mullite and corundum crystals is improved. The invention mainly increases the content of aluminum oxide in the formula of the green body by increasing the addition of calcined bauxite. Preferably, the alumina content of the green body powder is 28.5-29.5 wt%.

In some embodiments, the chemical composition of the green body powder for preparing the high-strength full body ceramic rock plate green body comprises: by mass percentage, loss on ignition is 4.7-5.0%, SiO₂ 57.5-58.5％，Al₂O₃ 27.8-30％，Fe₂O₃ 0.75-1.0％，TiO₂ 0.58-0.66％，CaO 0.35-0.42％，MgO 1.1-1.2％，K₂O 2.1-2.4％，Na₂O2.5-2.7%. Various formulas are selected and debugged in the specific test process. The most representative of these are the following three formulations.

TABLE 1 chemical composition (wt%) of three different formulations of alumina content

TABLE 2 physicochemical properties of three different formulations of alumina content

The raw materials for preparing the green body powder material can comprise: selecting sodium stone powder, gold middlings, Shaoguan ball clay, water-washed ball clay, black talc, calcined bauxite, potassium aluminum sand, bentonite and Zhongshan black mud.

In some embodiments, the raw materials for the green body powder may include: by weight, 16.5-17.5 parts of selected sodium stone powder, 15.5-16.5 parts of gold middling, 5-7 parts of Shaoguo ball clay, 11-13 parts of water-washed ball clay, 2.5-3.5 parts of black talc, 16-18 parts of calcined bauxite, 19.5-20.5 parts of potassium aluminum sand, 1.5-2.5 parts of bentonite and 6.5-7.5 parts of Zhongshan black mud. The composition of the raw materials of the three different formulations of alumina content is shown in table 3.

TABLE 3 raw material composition (unit: g/part by weight) of three different formulations of alumina content

As can be seen from tables 1, 2 and 3, as the amount of calcined bauxite increased, the amount of alumina was increased from 23.8% to 29.04%, the change in the dry strength and shrinkage of the green body was small, and the flexural strength was increased from 62.19MPa to 74.01 MPa.

As can be seen from fig. 2 and table 4, the formulations with different alumina contents are composed of quartz, mullite, corundum and amorphous phase after firing, and as the alumina content increases, the contents of mullite and corundum phase in the formulations increase. From Griffith's strength theory, it is known that the strength of the porcelain body increases with its modulus of elasticity. Due to the elastic modulus (40X 10) of corundum⁴MPa) is much greater than mullite (9.8X 10)⁴MPa) and amorphous phase (7.2X 10)⁴MPa) and thus the flexural strength increases.

TABLE 4 Crystal phase (wt%) for three different formulations of alumina content

TABLE 5 semi-quantitative analysis (wt) of calcined bauxite

Combining the XRD pattern of the calcined bauxite in FIG. 3 and the semi-quantitative analysis of the calcined bauxite in Table 5, it can be seen that the calcined bauxite is mainly composed of corundum and mullite crystals, and thus is advantageous for increasing the crystal phase content. This is consistent with the present invention's increased alumina content in the green body formulation by the addition of calcined bauxite as described above.

The prolonged heat preservation time of the high-temperature zone has great influence on the mullite content, the grain size and the density of a green body. The test discusses the influence of different firing periods on the flexural strength, phase composition and other aspects of the green body on the basis of the formula No. 3. The experiment adopts roller kiln sintering, the sintering period is 75min and 120min respectively, and the sintering temperature is 1230 ℃. Flexural strength, water absorption, bulk density, phase composition and semi-quantitative analysis of the phases of the samples at different firing times are shown in tables 6, 7 and fig. 4, respectively.

TABLE 6 Effect of firing time on Green body Properties

As can be seen from Table 6, as the firing time was increased from 75min to 120min, the flexural strength of the green body increased from 66.58MPa to 74.01MPa, the water absorption rate decreased and the bulk density increased from 2.42g/cm3 to 2.44g/cm 3.

TABLE 7 semi-quantitative analysis (wt%) of phases of samples of different firing periods

As can be seen from FIG. 4 and Table 7, the crystal phases of the samples consisted of quartz, mullite, and corundum phases at different firing times. Along with the increase of the sintering period, the mullite content is obviously increased, and the quartz phase content is reduced. As can be seen from the SEM photographs of fig. 5 showing different firing times, the amount of pores in the green body is significantly reduced with the extension of the firing period, which is advantageous for the discharge of internal gas and the realization of dense sintering. Thus, as firing time increases, the bulk density and flexural strength of the green body increases.

In conclusion, the content of aluminum oxide and aluminum oxide in the formula of the blank is increased, and the flexural strength of the product is increased along with the increase of the content of aluminum oxide. This is because, with an increase in the alumina content, the corundum content and the amorphous phase content in the fired product increase. From Griffith's strength theory, it is known that the strength of the porcelain body increases with its modulus of elasticity. Modulus of elasticity of corundum (40X 10)⁴MPa) is much greater than mullite (9.8X 10)⁴MPa) and amorphous phase (7.2X 10)₄MPa). In some embodiments of the invention, the content of Amorphous-Amorphous phase after the green body is fired is 46-55%. The crystal phase content is 45-54%, and the Quartz SiO mainly comprises 17-24%₂17-24% Mullite-Mullite (3 Al)₂O₃·2SiO₂) And 3-11% Corundum-Corundum Al₂O₃。

In some embodiments, the green body powder is prepared by: the raw materials are weighed according to the proportion and put into a ball mill for ball milling to obtain slurry, and the slurry is pulverized (for example, powder is sprayed by a spray tower) to obtain blank powder. The moisture range of the blank powder is controlled to be 7.2-8.0%. In some embodiments, the specific gravity of the slurry may be 1.70 to 1.72. By controlling the slurry within this specific gravity range, the bulk density of the powder can be increased and the number of hollow particles can be reduced. By improving the volume weight of the powder, the powder is solid, and is less likely to be crushed in the transfer process, and the flowability is better.

TABLE 8 Properties at different milling times

Due to the different slurry fineness and the different surface energy of the particles, the firing temperature difference of the formula is larger finally. In some specific experiments of the present invention, the effect of ball milling time on the specific gravity of the slurry, the oversize (250 mesh), green body shrinkage and water absorption was investigated. The results are shown in Table 8.

As can be seen from table 8, when the ball milling time was 10min, the particles were coarse, the oversize was 6.49%, the water absorption was 4.11% (> 0.5%), and the degree of vitrification of the green body was low; when the ball milling time is increased to 30min, the screen residue is 0.21%, the granularity is obviously reduced, the water absorption is reduced to 0.077%, and the ceramic degree of the blank is greatly improved. This is due to the fact that as the ball milling time increases, the particles are under the grinding and impact of the pebbles, resulting in a decrease in particle size. And the sintering driving force is increased along with the reduction of the granularity, the diffusion distance of atoms is shortened, the solubility of the particles in a liquid phase is improved, the sintering process is accelerated, and meanwhile, the defects of the interior and the surface of the particles are increased under the grinding of the ball stone, so that the sintering performance of the powder is improved. Therefore, with the reduction of the particle fineness, the firing temperature of the formula is reduced, the degree of vitrifying of the green body is better, the higher the density is, and the shrinkage and the water absorption of the green body are respectively increased and decreased. In order to ensure that the ceramic degree of the blank is good, the cutting performance is excellent, and the sintering shrinkage meets the actual production requirement, the screen residue of the slurry is preferably 0.3-0.5% (250 meshes) and is most suitable.

The formula, chemical composition and sintering temperature range of the blank confirmed by pilot test are respectively shown in the following by combining the experimental results and actual production. The firing system 2 is a firing system before adjustment, the tortoise back of the blank is very bad (7-8 mm), and the firing system 1 is a curve corresponding to new operation according to the adjustment of the process. The main changes are as follows: a. the sintering period is prolonged. The longer the firing period, the stronger the diffusion of the components in the glaze, the more the reaction of the blank glaze is sufficient, the better the development of the intermediate layer, the uniform thermal stress among the blank glazes is promoted, the bonding property of the blank glaze is improved, and the effect of improving the deformation is achieved; b. the flatness of the green brick can be effectively adjusted by uniformly adjusting the opening degree of the upper and lower quenching pipes. For ultra-thick ceramic rock plates of 13.5mm, 15.5mm and even 20.5mm, if the blank is not well oxidized in the whole firing process, a black core phenomenon exists, and the flatness of the blank is out of control. The time of the oxidation period is properly prolonged, the upper temperature and the lower temperature of the oxidation area are kept in a relatively close range as much as possible, the purpose can be achieved by increasing the heights of the surface gun, the fire barrier and the fire baffle, and the upper surface shrinkage and the lower surface shrinkage of the green body are kept synchronous basically. As can be seen from FIG. 6, the sintering temperature range is within 1260-1290 ℃ range, and the sintering temperature range is wider.

As the size of ceramic products increases, higher demands are made on the strength of the products in order to avoid breakage during operation. When the strength of the green body is low, breakage is easily caused in the forming, conveying and the like processes. The strength of the dried green body is improved by adding a proper amount of green body reinforcing agent. In some embodiments, the green body strengthening agent is preferably added in an amount of 0.2 to 0.6%. Table 9 shows the effect of the addition of the green strength agents of 0%, 0.2%, 0.4% and 0.6% on the green strength.

TABLE 9 Effect of enhancer addition on green body Strength

As can be seen from table 9, the wet green strength did not change significantly with the increase in the reinforcing agent, and the dry green strength gradually increased. When the addition amount is more than 0.2%, the increase in dry strength is insignificant. This is because ceramic particles rely primarily on van der waals forces and capillary forces generated by the presence of small amounts of moisture between the particles when no reinforcing agent is added. When the reinforcing agent is added, the green body particles are wrapped by the high polymer material, and at the moment, hydrogen bond action is generated among the green body particles besides Van der Waals force and capillary force, so that the dry strength of the green body is enhanced. When the addition amount of the reinforcing agent is increased, hydrogen bonds are increased, and the strength of the dried blank is further enhanced. Since the increase in the strength of the dried body is insignificant when the addition amount is more than 0.2%, the addition amount of 0.2% is most preferable in view of the production cost.

Meanwhile, by adjusting parameters such as temperature, air quantity and the like of spray granulation, the powder with smooth particles, good fluidity and high particle strength is prepared. When the temperature of the kiln reaches 500-580 ℃, the reinforcing agent in the green body is completely carbonized and lost, and the performance of the ceramic tile cannot be influenced.

The better the powder forming performance, the stronger the adaptability to the press. Meanwhile, the good powder fluidity is beneficial to the uniformity and the whole body effect of the material distribution of the press. The invention is mainly researched from the following aspects:

(1) improve the wet strength of the powder

The clay in the blank powder raw material greatly influences the wet strength of the powder and the whiteness of the product. Clay is a mixture of many mineral particles of different sizes and different physical, chemical and mineralogical properties, has plasticity and binding property, and is a basic raw material for ceramic production. When the iron and titanium contents in the clay raw material are higher, the whiteness is obviously reduced after firing. Several representative clays that can be used in the formulations are compared in terms of whiteness, flow rate, wet green strength, and dry strength, and the specific results are shown in table 10.

TABLE 10 basic physical Properties of Clay

Wherein: wherein 1) Shaoguan ball soil and water washing ball soil: is prepared from black mud, kaolin, sodium humate, etc. Ball clay is prepared by desanding, acid washing, iron removing and filter pressing; 2) high-strength washing mud: the raw ore mud is processed by washing with water to remove sundries such as branches and the like; 3) high-white bentonite: the Henan Xinyang high-whiteness bentonite is selected, so that the reinforcing effect is good; 4) zhongshan black mud: the raw ore black mud in the Zhongshan area is used. According to table 10, it is reasonable to select the shaoguan ball clay and bentonite for formulation adjustment.

(2) Increase the volume weight of powder and reduce hollow particles

The volume weight of the powder is improved, the powder is solid, the powder is not easy to break in the transfer process, and the flowability is good. The method is mainly achieved by increasing the specific gravity of the slurry to 1.70-1.72 and adjusting parameters such as the temperature and the air quantity of the spray tower for granulation.

(3) Reasonable particle size distribution

In some embodiments, the green body powder grain composition comprises: 8-18% above 30 meshes, 30-60 meshes: 70-80%, 60-80 mesh: 6-15% and less than 6% below 80 meshes.

In a specific test process, the invention compares the flowability of powder under different particle size compositions. Table 11 below shows a comparison of the flowability of the powder compositions of different green bodies. As can be seen from Table 11, the larger the volume weight of the powder, the larger the 30-mesh particle, and the better the flowability.

TABLE 11 comparison of the flowability of the powders at different particle sizes

FIG. 7 is a comparison of green body powder and conventional ceramic green body powder at 50 times magnification according to one embodiment of the present invention. As can be seen from FIG. 7, the green body powder used in the present invention is mostly spherical, smooth in appearance, and good in flowability, which is beneficial to the distribution and molding of the press. The common ceramic tile powder is irregular in shape, and the surface of the common ceramic tile powder is provided with more burrs formed by broken fine powder, so that the powder is strong in adhesion, poor in fluidity and easy to form powder balls.

According to preliminary conjecture, the ceramic plate stress is caused by the fact that a ceramic material blank is composed of crystals, non-crystals and pores into a non-homogeneous body, and the stress distribution difference is caused by the uneven distribution of phases and pores, so that the density and the uniformity of the blank are improved, and the improvement of the stress distribution of the ceramic material is greatly facilitated. The breakage of the architectural ceramic material along the crystal is mainly used when the architectural ceramic material is broken, and the crystal in the blank body is still kept complete when the product is broken, so the content of the crystal phase and the bonding strength between the crystal phases determine the strength of the ceramic tile and the performance of later processing; the higher the crystalline phase content in the product is, the higher the green body strength is, and the later-stage processing performance is also improved. The heat preservation time of a high-temperature area is prolonged when the ceramic material is sintered, and the generation of mullite, feldspar and other crystals in the blank body can be promoted, so that the mechanical strength of the finished product is improved. In addition, the content of free quartz and the grain size of the free quartz in the sintered blank also influence the processing performance of the ceramic material, and because the quartz can generate crystal transformation at 574 ℃, in the cooling process, when the high-temperature quartz is transformed into the low-temperature quartz, cracks can be generated along the quartz grains along with the shrinkage of the grain size, so that the mechanical processing performance of the ceramic product is reduced. Three basic raw materials of ceramics: the mullite-containing ceramic material comprises clay, quartz and fluxed raw materials, wherein a mullite crystal phase generated after the clay is sintered can improve the mechanical strength, thermal stability and chemical stability of a sintered product. The clay raw material with low content of free quartz and low loss after firing is selected, so that the improvement of the processing performance of the ceramic product can be greatly promoted; meanwhile, in the raw material mixing ball milling process, the ball milling time is properly prolonged, the quartz in the raw materials is milled to be finer, and the size of cracks of the burnt free quartz in the crystal form conversion process is controlled, so that the mechanical strength of the product is improved. According to the invention, by selecting proper blank powder chemical components, particle grading, ball milling process and the like, the obtained powder has good forming performance and stronger adaptability to a press, and meanwhile, the good powder fluidity is beneficial to the uniformity and the whole body effect of the material distribution of the press.

In addition, the natural stone has consistency in external appearance and internal appearance, and the traditional ceramic tile is difficult to achieve in effect, so that huge contrast formed by the decorative effect of blanks with different colors inside and the ceramic tile glaze is obviously seen when the natural stone is subjected to treatment such as grooving, chamfering and arc in later-stage deep processing. In order to solve the problem of inconsistent inside and outside of the rock plate, the color of the blank is close to the surface effect or even consistent through a color mixing mode.

At present, the color mixing process mainly comprises wet ball milling color mixing and dry color mixing, and the ratio of the color mixing quality of the wet ball milling color mixing and the dry color mixing is shown in table 12. As can be seen from Table 12, although the dry blending method has the advantages of convenient production conversion, no slurry pool occupation, etc., the dry blending method also has the disadvantages of color variation of powder, easy layering in press molding, etc.

TABLE 12 wet ball-milling color mixing and dry color mixing

Table 13 shows the volume weight, particle fineness and flow rate of the powder before and after dry-blending. As can be seen from Table 13, the amount of fine powder of 80 mesh or less increased significantly after the dry-blending step, resulting in poor flowability, and the poor flowability of the fine powder caused the powder to stick to the roller wall and cause delamination (see FIG. 8). From FIG. 9, 3% pigment is added to wet and dry color-mixed color cakes (first row wet ball milling color mixing, second row dry ball milling color mixing), the wet ball milling color-mixed powder is better colored and has no white particles, while the dry color-mixed powder is poorer colored and is mixed with white particles which are not wrapped by the pigment. Therefore, wet ball milling color mixing will not result in increased powder subdivision and poor flowability. Meanwhile, the powder is better colored.

TABLE 13 Properties of the powders before and after Dry blending

FIG. 10 is a graph showing the relationship between the powder breakage rate after dry-mixing of 1kg of a coloring material and 250kg of a base material at a stirring speed of 20 rpm as a function of the dry-mixing time, and FIG. 11 is a graph showing the relationship between the powder breakage rate after dry-mixing of 1kg of the coloring material and 250kg of the base material for 10 minutes as a function of the dry-mixing speed. It is known that the breakage rate of the powder material increases along with the extension of the dry mixing time or the increase of the dry mixing rotating speed, and the wet ball milling color mixing adopts the slurry color mixing and then the spray granulation mode does not increase the breakage of the powder material.

According to the analysis, considering that the requirement of large-size products on the powder forming performance is higher, a wet ball milling color mixing process is selected.

Then distributing the blank powder and pressing into a blank. The size of the blank body can be 760-1600 mm in width, 1800-3600 mm in length and 5.5-20.5 mm in thickness. For example, 1600 mm. times.3600 mm. times.15.5 mm, 1200 mm. times.2400 mm. times.13.5 mm, 1200 mm. times.2400 mm. times.5.5 mm, 760 mm. times.2550 mm. times.13.5 mm, 900 mm. times.1800 mm. times.10.5 mm, 900 mm. times.1800 mm. times.5.5 mm. The surface area may be up to 5.76 square meters. The thickness may be 13.5mm, 15.5mm or even 20.5 mm. In some embodiments, a full body ceramic rock plate blank is shown in fig. 12.

In some embodiments, the green body powder is distributed in a manner completely different from the conventional grid distribution, but a belt-in type distribution is adopted. If the ceramic plate with the ultra-large specification of 1600mm multiplied by 3600mm and the like adopts the traditional grid distribution, the grid size is very large, the rigidity of the ceramic plate is difficult to ensure, the packing thickness is uneven, and the dimensional precision of the green brick cannot be ensured. The problem of the belt stretching-in cloth does not exist. 1200 × 2400mm, 760x2550mm and 900mmx1800mm are traditional grid cloth, the size is smaller, the operation is simple, and the size is better controlled.

The green body may then be dried, for example in a drying kiln. The drying temperature can be 200-250 ℃, the drying time can be 90min, and the moisture of the dried blank is controlled within 0.4%.

Subsequently, a cover glaze is applied on the dried green body. The overglaze can be applied by spraying glaze. In some embodiments, the overglaze is applied at an amount of 520-580g/m²。

Preferably, the chemical composition of the overglaze may include: IL (ignition loss) 4-5% and SiO in percentage by mass₂50.7～51.5％，Al₂O₃ 29.0～30.5％，Fe₂O₃ 0.2～0.3％，CaO 0.35～0.50％，MgO 0.1～0.2％，K₂O 5.5～6.5％，Na₂O2.0～2.5％，ZrO₂5.9 to 6.5 percent. Tests show that the overglaze formula can be used for developing color and glazing effectPreferably.

However, because the firing period and the high-temperature heat preservation time of the thick ceramic plate product are longer, the temperature of the overglaze formula is slightly lower, the whiteness is deteriorated, and a few pinholes and miliaria appear on the brick surface.

Further preferably, the chemical composition of the overglaze may comprise: by mass percentage, the burning loss of IL is 4-5%, and SiO is₂ 50.9～51.3％，Al₂O₃ 29.8～30.3％，Fe₂O₃ 0.2～0.3％，CaO 0.35～0.45％，MgO 0.1～0.15％，K₂O 5.6～6.0％，Na₂O2.0～2.2％，ZrO₂6.1 to 6.4 percent. By increasing the contents of the high-aluminum material and the zirconium silicate on the basis of the original overglaze formula, the firing temperature of the overglaze is correspondingly increased, and the defects of miliaria, pinholes and the like on the surface of the brick in the production process are effectively solved. In some embodiments, the firing temperature of the overglaze is 1200 to 1250 ℃.

The soft glaze can be applied after the pattern is printed on the green body with the overglaze by ink-jet printing. The soft glaze layer can also be directly coated on the overglaze layer. The ink can be printed by a digital ink-jet printer. The ceramic ink used may be blue, reddish brown, orange, golden yellow, lemon yellow, black, red, etc. The specific decorative pattern, texture and color effect are determined according to the design requirements.

The blank printed with the ink-jet pattern is then dried.

The application range of the ceramic thick plate is expanded to occasions where the cupboard, the dining table top and the like contact with food, and the surface is required to have the performances of high temperature resistance, scratch resistance, acid and alkali resistance, easy cleaning, no toxicity and the like. Therefore, in the development of glaze, the materials need to be selected and developed from the following points: 1) safety and sanitation: can be in direct contact with food; 2) fireproof and high temperature resistant: the direct contact with high temperature objects can not deform; 3) impermeability: the porcelain is completely vitrified, stains cannot permeate, and no space is provided for breeding bacteria; 4) scratch resistance: the Mohs hardness exceeds 5 grade, and the scratch can be resisted; 5) corrosion resistance: resistance to various chemicals, including solutions, disinfectants, acid and base chemicals, etc.; 6) easy cleaning: the cleaning can be realized only by wiping with a wet towel, no special maintenance requirement is needed, and the cleaning is simple and quick. And simultaneously, the flatness of the ceramic rock plate is required to be met.

And then applying high-transparency dry grain glaze on the surface of the dried blank. The glazing mode of the high-transparency dry particle glaze can be a belt dry particle glaze distribution mode. In some embodiments, the high-transparency dry granular glaze is applied in an amount of 800-850 g/m². The high-transparency dry particle cloth is utilized to form a dry particle layer with a certain thickness, and the dry particle layer is polished after being fired, so that the product has clear patterns, good wear resistance, excellent antifouling property and high mirror surface degree. The dry grain full-polished glaze integrates the advantages of antique products and polished products, and has smooth and bright glaze surface like polished tiles, high mirror surface degree, rich patterns like antique tiles and gorgeous colors.

The chemical composition of the high transparent dry-particle glaze (which may also be referred to as high-temperature frit dry particles) may include: by mass percentage, the loss on ignition is 0.45-0.55%, and SiO is₂ 63～64％，Al₂O₃ 8.5～9.0％，CaO 9.5～10.5％，MgO 0.3～0.4％，BaO 1.0～1.2％，K₂O 6.5～7.0％，Na₂O 1.0～1.2％，ZnO9.2～9.8％。

In one embodiment, the chemical composition of the raw materials used for the high temperature frit dry pellets is shown in table 14.

TABLE 14 chemical composition of raw materials used for the frits (wt%)

The research on the formula of the high-transparency dry granular glaze mainly solves the problems of permeability, pores and wear resistance of the high-transparency dry granular glaze.

The main influencing factors influencing the transparency of the glaze layer are as follows: firstly, the firing temperature is too high, so that dry particles are over-fired, and excessive bubbles exist in the glaze layer; secondly, the sintering temperature is not enough, so that dry particles are not burned enough; ③ the glaze layer is internally provided with cotton-shaped devitrification.

Aiming at the first step and the second step, the initial melting point of dry particles needs to be adjusted. The specific test results are shown in Table 15 below. Preferably, the high-transparency dry-particle glaze has an initial melting point of 760 and 790 ℃.

And thirdly, the firing period is shortened mainly by adjusting the firing curve of the kiln, and the phenomenon of flocculent devitrification in the glaze layer can be well avoided. The flocculent crystallization is caused by calcium barium crystal formed in the firing process.

TABLE 15 adjustment of melting Point and test results

The glaze layer bubbles and glaze pinholes are mainly expressed in that a large number of dense fine pores are remained on the surface after polishing; ② after polishing, the surface has large pinholes, but is comparatively dispersed. The fundamental reason for the above two defects is that a large number of bubbles exist in the glaze layer and become open pores after polishing. Meanwhile, the antifouling property is poor, and the appearance effect of the green brick is influenced.

The dry particle level has a great influence on the bubbles in the glaze layer. Therefore, in the experiment, the proper grain composition is selected mainly by comparing the proportion of coarse and fine grains at two ends (60-80 meshes and 120-250 meshes), and the table 16 shows the influence of different dry grain compositions on the bubbles of the glaze layer.

TABLE 16 influence of different dry grain size distributions on glaze layer bubbles

As is clear from Table 16, it was found that when the proportion of particles of 60 to 80 mesh is more than 35%, the glaze layer shows "orange peel" after firing, and large bubbles are increased in the glaze layer. When the proportion of the particles of 120 meshes to 250 meshes is close to 35 percent, a large amount of small bubbles appear on the glaze layer after firing.

FIG. 13 is a diagram showing the state of bubbles in 4 sets of different dry grain size distribution underglaze layers. By comparing the glaze layer bubbles and the surface polishing effect after firing, a more appropriate grain composition is obtained: 30-32% of 60-80 meshes, 15-18% of 80-100 meshes, 22-25% of 100-120 meshes, 30-32% of 120-250 meshes, and less than 1% below 250.

The direct spreading of the frit dry particles after the inkjet printing is likely to cause phenomena such as glaze pits, glaze shrinkage, etc. (as shown in fig. 16 and 17). At the same time, in order to ensure that the color of the ink is betterBright and cohesive, therefore, a layer of dielectric glaze needs to be sprayed after ink-jet printing. The requirement of sufficient permeability is met, and the glazing moisture is not too large, mainly because the water is converted from liquid state to gas state in the volatilization process to cause volume expansion, and the dry particle layer can be broken to form bubbles. The chemical components of the dielectric glaze comprise, by mass percent, 5.0-5.5% of loss on ignition and SiO₂ 55～57％，Al₂O₃ 17～18％，Fe₂O₃ 0.1～0.2％，TiO₂0.1～0.2％，CaO 6.5～7.0％，MgO 2.0～2.3％，K₂O 3.3～3.6％，Na₂2.8-3.0% of O, 3.7-4.0% of ZnO3 and 1.5-1.8% of BaO. In some embodiments, the dielectric glaze is applied in an amount of 40-50 g/m². Influence of frit dry particle distribution on pores and polishing: the more dry particles, the more difficult it is to exhaust and the more gas is trapped in the glaze layer. The amount of dry particles is too small, and the phenomena of bottom exposure and surface water ripple can occur after polishing. The results of the experiments are shown in Table 17 below.

TABLE 17 Effect of dry particle distribution on pores and polishing

As can be seen from Table 17, the optimum range of the amount of the transparent dry granules to be applied is 800 to 850g/m²。

After the transparent dry-particle frits are spread, the glaze line is directly moved, the spread dry-particle frits are easy to blow away, a layer of fixing agent is needed to be sprayed on the glaze line, and the fixing agent can be glue commonly used for glaze. Because the dry particle layer is the accumulation of frits, in order to prevent that too big frit is broken up or local too much glaze has the pit that causes at the spraying in-process, consequently, will guarantee reasonable atomization effect. In the concrete implementation mode, the pressure requirement of the spray gun cannot exceed 1MPa, 2 nozzles are adopted, the hole diameter is 0.43mm, and the angle is 110 degrees. In practical use, the fixing agent is mixed with water according to a certain proportion, such as 1: (1-3).

The experiments were designed as in table 18 below.

TABLE 18 fixative and amounts used

The greater the amount of fixing agent sprayed in for the layer of dry particles spread, the greater the strength of the fixing. However, in practical production, the moisture content of the green bricks entering the kiln is required to be controlled to be 0.85-0.95%, otherwise brick frying is easily caused. The following table 19 shows the moisture content of the green body at the same time and temperature by placing the fixing agent-sprayed green body in an oven according to the scheme of table 18.

Moisture content change of table 193 different schemes with drying time

As is clear from Table 19, when the same amount of glaze was sprayed, the larger the proportion of water, the more easily the water was volatilized. The fixed dose in protocol 3 was 210g/m at 10min depending on the production conditions²Can meet the production requirements, so the fixed dose of the selected scheme 3 is 210g/m²As a production process parameter.

Comparing the full-polished dry grain glaze with the common full-polished glaze product

FIG. 14 is a photograph of the high transparent dry-grain glaze of the present invention and the surface of the ordinary polished glaze magnified by 50 times with an optical microscope, and it can be seen from FIG. 14(a) that the glaze layer of the dry-grain polished product has few bubbles, and no white spots caused by obvious wax water after polishing and waxing, which shows that after polishing, the open pores on the brick surface are few; in fig. 14(b), the conventional glaze polishing layer has a relatively large number of bubbles, and the brick surface is filled with a large number of white wax water white spot residues, which indicates that the polished glaze polishing product has a large number of open pores. The bubbles in the glaze layer can cause refraction to light, thereby reducing the permeability of the glaze layer, the more the bubbles, the lower the definition, and the less the bubbles in the dry grain glaze layer, therefore, the pattern is clearer.

The requirements of the novel ceramic thick plate are different from those of the traditional large plate, compared with the ceramic large plate, the thick plate can be drilled, polished and cut more conveniently, and is suitable for making various shapes. Has the following advantages: 1) safety and sanitation: can be in direct contact with food. 2) Fireproof and high temperature resistant: the object directly contacting the high temperature does not deform. 3) Stain resistance: the stain can not permeate, and meanwhile, the space for breeding bacteria is not provided. 4) Scratch and wear resistance: the Mohs hardness exceeds 5 grades, and can resist scratching and attempted scratching. 5) Corrosion resistance: resistant to various chemicals including solutions, disinfectants, and the like. 6) Easy cleaning: the cleaning agent can be cleaned only by wiping with a wet towel, has no special maintenance requirement, and is simple and quick to clean.

The present invention will be described in detail by way of examples. It is also to be understood that the following examples are illustrative of the present invention and are not to be construed as limiting the scope of the invention, and that certain insubstantial modifications and adaptations of the invention by those skilled in the art may be made in light of the above teachings. The specific process parameters and the like of the following examples are also only one example of suitable ranges, i.e., those skilled in the art can select the appropriate ranges through the description herein, and are not limited to the specific values exemplified below.

1. And preparing blank powder. The chemical components of the green body powder comprise: loss on ignition of 4.9% and SiO in mass percent₂ 58.08％，Al₂O₃ 28％，Fe₂O₃ 0.78％，TiO₂ 0.6％，CaO 0.39％，MgO 1.13％，K₂O 2.3％，Na₂O 2.63％，ZrO₂。

The raw materials for preparing the green body powder comprise: the material comprises, by weight, 17 parts of selected sodium stone powder, 16 parts of gold middling, 6 parts of Shaoguo ball clay, 12 parts of water-washed ball clay, 3 parts of black talc, 17 parts of calcined bauxite, 20 parts of potassium aluminum sand, 2 parts of bentonite and 7 parts of Zhongshan black mud. The raw materials are weighed according to the proportion and put into a ball mill for ball milling to obtain slurry, and the slurry is pulverized (for example, powder is sprayed by a spray tower) to obtain blank powder. The specific gravity of the slurry may be 1.71. The moisture range of the green body powder is controlled to be 7.6 percent. The fineness of the ball milling can be 0.4% (250 mesh).

2. Pressing the green body powder into a green brick. Press process parameters of the blank: the molding pressure was 120000N and the press frequency was 2.0 times/min.

3. Drying the green body by using a drying kiln, wherein the drying temperature is as follows: 225 ℃, drying time: and (5) drying for 90min until the dry moisture is less than 0.4%.

4. And spraying a surface glaze on the dried green body. The application amount of the overglaze is 550g/m². Examples 1-3 differ in that: the overglaze formulation varied, with example 1 using overglaze a, example 2 using overglaze B and example 3 using overglaze C. The chemical compositions of the above three overglaze are shown in Table 20. The whiteness and the expansion coefficient of the above three overglaze formulations are shown in table 21.

TABLE 20 examples 1-3 chemical composition (wt/%) of three overglaze formulations

TABLE 21 whiteness and expansion coefficients of three overglaze formulations

5. And (4) carrying out ink-jet printing on the blank body after the surface glaze is sprayed. The inkjet type is desirably TO 2000-1733-8-L. Inkjet printing inkjet machine parameters are shown in table 22 below.

TABLE 22 inkjet parameters

6. And drying the blank after ink-jet printing.

7. Spraying medium glaze on the dried blank body, wherein the cloth amount is 45g/m². The chemical composition of the dielectric glaze is shown in Table 23.

TABLE 23 chemical composition of dielectric glaze (wt%)

8. Applying high-transparency dry-grain glaze on the blank body after spraying the medium glaze, and distributing the high-transparency dry-grain glazeThe amount is 830g/m². The chemical composition of the highly transparent dry-grain glaze is shown in Table 24.

TABLE 24 chemical composition (wt%) of the frit dry particles

9. And then quickly firing by a roller kiln, edging, grading and packaging. The maximum firing temperature is 1230 ℃, and the firing period is 150 min. The firing cycle and temperature are related to the gauge and thickness of the rock plate.

Example 4

Example 4 is essentially the same as example 1, except that: the raw material formulation of the overglaze is shown in table 10. The raw material formulation of the overglaze is shown in table 25.

Table 25 overglaze formulation composition units for example 4: keke (Chinese character of 'Keke')

TABLE 26 overglaze chemical composition analysis of example 4

The contents of silicon, aluminum and zirconium are increased on the basis of the overglaze formula of the original formula B, the firing temperature of the overglaze is correspondingly increased, and the problems of brick surface miliaria, pinholes and the like in the production process are effectively solved.

Claims

1. The preparation method of the high-transparency polished ceramic thick plate is characterized by comprising the following steps of:

preparing a high-strength through-body ceramic thick plate blank by using blank powder, wherein the strength of the blank is 2.8-3.5 MPa; the chemical components of the green body powder material comprise: by mass percentage, the loss on ignition is 4.7-5.0%, and SiO is₂ 57.5～58.5%，Al₂O₃ 27.8～30%，Fe₂O₃ 0.75～1.0%，TiO₂0.58～0.66%，CaO 0.35～0.42%，MgO 1.1～1.2%，K₂O 2.1～2.4%，Na₂O 2.5～2.7%；

Spreading overglaze on the blank body, wherein the glazing amount of the overglaze is 520-580g/m²；

Printing a pattern on the blank body coated with the overglaze in an ink-jet manner;

spreading dielectric glaze; the chemical composition of the dielectric glaze is as follows: loss on ignition of 5.0-5.5%, SiO₂55～57%，Al₂O₃ 17～18%，Fe₂O₃ 0.1～0.2%，TiO₂0.1～0.2%，CaO 6.5～7.0%，MgO 2.0～2.3%，K₂O 3.3～3.6%，Na₂2.8-3.0% of O, 3.7-4.0% of ZnO and 1.5-1.8% of BaO; the glazing amount of the dielectric glaze is 40-50 g/m²；

Distributing high-transparency dry granular glaze with an initial melting point of 760-790 ℃; the chemical composition of the high-transparency dry granular glaze is as follows: 0.45-0.55% loss on ignition, SiO₂63～64%，Al₂O₃ 8.5～9.0%，CaO 9.5～10.5%，MgO 0.3～0.4%，BaO 1.0～1.2%，K₂O 6.5～7.0%，Na₂1.0-1.2% of O and 9.2-9.8% of ZnO; the grain composition of the high-transparency dry grain glaze is as follows: 30-32% of 60-80 mesh, 15-18% of 80-100 mesh, 22-25% of 100-120 mesh, 30-32% of 120-250 mesh, and less than 250 mesh<1 percent; the glazing amount of the high-transparency dry granular glaze is 800-850 g/m²；

Firing at 1200-1290 ℃ for 75-180 min;

and manufacturing the large-size ceramic thick plate.

2. The method according to claim 1, characterized in that the grain composition of the green body powder comprises: 8-18% of 30 meshes above, 70-80% of 30-60 meshes, 6-15% of 60-80 meshes and less than 6% of 80 meshes below.

3. The method according to claim 1, wherein the overglaze comprises the following chemical components: by mass percentage, loss on ignition is 4-5%, and SiO is₂50.7～51.5%，Al₂O₃29.0～30.5%，Fe₂O₃0.2～0.3%，CaO 0.35～0.50%，MgO 0.1～0.2%，K₂O 5.5～6.5%，Na₂O2.0～2.5%，ZrO₂5.9～6.5%。

4. The thick high-transparency polished ceramic plate obtained by the method for producing a thick high-transparency polished ceramic plate according to any one of claims 1 to 3, wherein the thick ceramic plate has a width of 760 to 1600mm, a length of 1800 to 3600mm, and a thickness of 5.5 to 20.5 mm.