Low-temperature fired self-releasing glaze feldspar domestic ceramic and preparation method thereof

Abstract

The invention discloses a low temperature fired self-releasing glaze feldspar domestic ceramic, which is prepared by mixing main materials and additives, the main materials comprise the following components by weight: 20-30% of kaolin, 15-25% of quartz, 35-40% of wollastonite, 12-15% of potassium feldspar, 0-1% of talc, and 0-5% of calcined alumina; the additive is a feldspar porcelain waste material. The invention also discloses a preparation method of the low-temperature fired self-releasing glaze feldspar domestic ceramic. According to the low-temperature fired self-releasing glaze feldspar domestic ceramic and the preparation method thereof, through collaborative optimization of a formula and a firing system, low-temperature firing at 1120-1150 DEG C is achieved, a compact and smooth glaze layer can be spontaneously formed in the firing process of a green body, a traditional glazing procedure is omitted, and an obtained product is high in strength, low in water absorption rate, smooth in glaze surface and good in durability. The method has the remarkable advantages of saving energy, reducing consumption and simplifying the process.

Description

Technical Field

[0001] This invention belongs to the field of daily-use ceramic materials technology, specifically, it relates to a low-temperature fired self-releasing glaze feldspar daily-use ceramic and its preparation method. Background Technology

[0002] Feldspar porcelain is a major variety of daily-use and arts-and-craft porcelain, highly favored for its hard texture and smooth glaze. However, its core firing process typically requires temperatures between 1200℃ and 1400℃, with actual production often concentrated in the range of 1250~1350℃. This is because temperatures below 1250℃ may result in incomplete sintering of the porcelain body, leading to insufficient transparency and strength; while temperatures above 1350℃ may cause deformation or overfiring defects. With modern process optimization, the optimal firing temperature is often controlled between 1280~1330℃ to balance porcelain properties and production efficiency. This results in a highly energy-intensive and costly production process. Against the backdrop of continuously rising global energy prices and the in-depth implementation of my country's "dual-carbon" strategy, the high energy consumption of the ceramics industry has become a key bottleneck restricting its sustainable development. Promoting quality improvement, energy reduction, and technological upgrading in the ceramics industry is now imperative. Research shows that for every 100℃ reduction in firing temperature, the energy consumption per unit product can be significantly reduced by more than 10%. Adopting low-temperature firing technology is undoubtedly an effective way for the daily-use ceramics industry to save energy and reduce consumption. This technology can reduce manufacturing costs, improve production efficiency, shorten the firing cycle, and reduce environmental pollution. However, low-temperature firing of ceramics refers to a peak firing temperature between 700℃ and 1150℃. This temperature range results in the body not being fully vitrified, the texture being relatively loose, and the glaze appearance being significantly different from that of high-temperature ceramics, which cannot meet the firing requirements of daily-use ceramics.

[0003] Furthermore, traditional ceramic production requires a separate glazing process, which is complex and significantly increases the production cost of ceramic products. Self-releasing glaze technology eliminates the traditional necessary steps of glazing, glazing, and secondary firing, while still achieving the desired glazing effect, greatly streamlining the production process and effectively reducing costs. However, although self-releasing glaze products have a smooth and delicate surface, certain properties, such as glaze richness and fullness, and the strengthening and toughening effects of new ceramic materials, are still inferior to traditional daily-use ceramics. Moreover, the sintering temperatures of currently reported self-releasing glaze daily-use ceramics are generally still relatively high (1150~1400℃), which cannot meet the relative demands of daily-use ceramics or achieve the goals of energy conservation and emission reduction. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a self-releasing feldspar daily-use ceramic that can be fired at a lower temperature and forms a glaze layer without additional glazing, and a method for preparing the same.

[0005] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: A type of low-temperature fired, self-releasing glaze feldspar daily-use ceramic is prepared by mixing main materials and additives. The main material comprises the following components by weight percentage: kaolin 20-30%, quartz 15-25%, wollastonite 35-40%, potassium feldspar 12-15%, talc 0-1%, and calcined alumina 0-5%; The additive is feldspar porcelain waste; The amount of the additive added is 3-5% of the total mass of the main material; The peak firing temperature of the self-releasing glaze feldspar daily-use ceramics is 1120℃~1150℃.

[0006] The preparation method of the above-mentioned low-temperature fired self-releasing glaze feldspar daily-use ceramic of the present invention includes the following steps: For ingredient preparation, weigh and mix the main ingredients according to the ratio, and weigh and crush the additives according to the ratio to a particle size ≤50μm for later use. Ball milling involves feeding the main material and additives into a ball mill, while adding water (60% to 80% of the total dry weight of the raw materials) and water glass (0.1% to 0.5%) for wet ball milling. Filter the ball milling liquid and pass it through a 325-mesh sieve to obtain ball milling slurry; Drying: The ball mill slurry is placed in a dryer for drying. The dried ball mill slurry is crushed and ground, and then passed through a 60-mesh sieve to obtain raw material powder. Dry pressing involves feeding raw material powder into a molding machine for dry pressing to produce a green body. Firing involves placing the raw ceramic blanks into a kiln for firing at a peak temperature of 1120℃~1150℃ for 5~8 hours. After firing, the blanks are cooled to room temperature to obtain self-releasing glaze feldspar daily-use ceramics.

[0007] The present invention has the following beneficial effects: (1) By combining wollastonite and kaolinite, calcium feldspar crystal phase is generated at around 900℃. When the sintering temperature is greater than 1100℃, calcium feldspar, potassium feldspar and feldspar porcelain waste melt and dissolve wollastonite, quartz and other crystal phases to form a low eutectic glass phase, thereby successfully reducing the peak firing temperature to 1120℃~1150℃, achieving the purpose of energy saving and emission reduction.

[0008] (2) During the firing process, the body contains calcium feldspar, quartz and wollastonite crystal phases, which makes the body form a porous capillary structure. At 1100~1150℃, the body produces a low eutectic glass phase. Under the action of the capillary, an appropriate amount of glass phase will migrate to the surface on its own to form a uniform, dense and smooth glaze layer. That is, the self-releasing glaze does not need to add a self-releasing agent. At the same time, it can save the processes of glaze making, glazing and secondary firing, reducing labor costs and glaze costs.

[0009] (3) One of the key issues in forming a self-releasing glaze is to form an appropriate amount of glass phase in the green body. If the glass phase content is too low, it is difficult for the green body to form a glaze layer; if the glass phase content is too high, the product is prone to deformation during sintering. This invention, through reasonable formula design, optimization of sintering process, and control of the amount of glass phase generated, keeps the glass phase content of the product within the range of 40% to 55%. While promoting the densification of the green body and generating a self-releasing glaze, it avoids the excessive dissolution of crystalline phases such as quartz, anorthite, and residual wollastonite, thereby simultaneously achieving low water absorption and high mechanical strength of the product.

[0010] (4) Feldspar ceramic waste hardly undergoes secondary shrinkage during the firing process. When added to the body, it can effectively improve the high-temperature strength of the body during the firing process, prevent the body from sintering and deforming, and realize the resource utilization of solid waste, which helps to realize the circular economy of the ceramic industry. Attached Figure Description

[0011] Figure 1 The image shows the XRD pattern of the self-releasing glaze feldspar ceramic obtained in Example 3 of this invention.

[0012] Figure 2 This is a SEM image of the self-releasing glaze feldspar ceramic obtained in Example 3 of the present invention.

[0013] Figure 3 These are photographs of the ceramics obtained in Example 1 (left) and Comparative Example 1 (right) of the present invention. Detailed Implementation

[0014] The present invention will now be described in detail with reference to the embodiments.

[0015] The present invention provides a low-temperature fired self-releasing glaze feldspar daily ceramic, the phase composition of which includes quartz, calcium feldspar, wollastonite and glass phase, the glass phase content of which is 40%~55%, and the surface of which has a uniform thickness, dense and smooth glaze layer, which is prepared by mixing the main material and additives.

[0016] The main ingredients include the following components by weight percentage: 20-30% kaolin, 15-25% quartz, 35-40% wollastonite, 12-15% potassium feldspar, 0-1% talc, and 0-5% calcined alumina.

[0017] The additive is feldspar ceramic waste; its chemical composition by weight percentage includes the following components: silicon dioxide 65-75%, aluminum oxide 18-25%, potassium oxide 3-7%, sodium oxide 0-1%, and magnesium oxide 0.5-3%.

[0018] The amount of the additive added is 3 to 5% of the total mass of the main material.

[0019] The peak firing temperature of the self-releasing glaze feldspar daily-use ceramic is 1120℃~1150℃. The prepared self-releasing glaze feldspar daily-use ceramic has a flexural strength >100 MPa, a water absorption rate <0.05%, and a Vickers hardness of the glaze surface >7.5 GPa. Example 1

[0020] The preparation method of a low-temperature fired self-releasing glaze feldspar daily-use ceramic according to Embodiment 1 of the present invention includes the following steps: For the ingredients, weigh out 30% kaolin, 16% quartz, 40% wollastonite, 13% potassium feldspar, and 1% talc by weight percentage and premix them. Weigh out 4% of the total mass of feldspar porcelain waste and crush it to a particle size ≤50μm for later use.

[0021] Ball milling: The main material and additives are fed into a ball mill, along with water (80% of the total dry weight of the raw materials) and 0.1% water glass. The mixture is then wet-milled at 400 rpm for 1 hour.

[0022] Filter the ball milling liquid through a 325-mesh sieve to obtain a uniform ball milling slurry.

[0023] Drying: Place the ball mill slurry in a dryer and dry at 100℃ for 6 hours.

[0024] The dried ball mill slurry is crushed and sieved, and then passed through a 60-mesh sieve to obtain raw material powder.

[0025] Dry pressing involves feeding raw material powder into a molding machine for dry pressing. Utilizing the natural plasticity of kaolin in the raw material, the powder can be polymerized and molded into a green body without the addition of binders.

[0026] Firing involves placing the green ceramic blanks in a kiln and heating them to a peak firing temperature of 1120℃ at a rate of 5℃ / min, holding them at that temperature for 120 min. After firing, the blanks are cooled to room temperature in the kiln. The total firing cycle is 8 hours, resulting in self-releasing glaze feldspar daily-use ceramics. The main phase composition of the self-releasing glaze feldspar daily-use ceramics consists of wollastonite, quartz, anorthite, and a glassy phase, with the glassy phase content being 40%. Testing revealed a flexural strength of 130 MPa, a water absorption rate of 0.02%, a glaze thickness of 58 μm, a Vickers hardness of 7.68 GPa, and thermal stability with no cracks appearing after one heat exchange between 200℃ and 20℃. Example 2

[0027] The preparation method of a low-temperature fired self-releasing glaze feldspar daily-use ceramic according to Embodiment 2 of the present invention includes the following steps: For the ingredients, weigh out 21% kaolin, 20% quartz, 40% wollastonite, 14% potassium feldspar, 1% talc, and 4% calcined alumina by weight percentage and premix them. Weigh out 3% of the total mass of feldspar porcelain waste and crush it to a particle size ≤50μm for later use.

[0028] Ball milling: The main material and additives are fed into a ball mill, along with water (80% of the total dry weight of the raw materials) and 0.1% water glass. The mixture is then wet-milled at 400 rpm for 1 hour.

[0029] Filter the ball milling liquid through a 325-mesh sieve to obtain a uniform ball milling slurry.

[0030] Drying: Place the ball mill slurry in a dryer and dry at a drying temperature of 110℃ for 6 hours.

[0031] The dried ball mill slurry is crushed and sieved, and then passed through a 60-mesh sieve to obtain raw material powder.

[0032] Dry pressing involves feeding raw material powder into a molding machine for dry pressing to produce a green body.

[0033] Firing involves placing the green ceramic blanks in a kiln and heating them to a peak firing temperature of 1130℃ at a rate of 10℃ / min, holding them at that temperature for 60 minutes. After firing, the blanks are cooled to room temperature in the kiln. The total firing cycle is 5 hours, resulting in self-releasing glaze feldspar daily-use ceramics. The main phase composition of the self-releasing glaze feldspar daily-use ceramics consists of quartz, anorthite, wollastonite, and a glassy phase, with the glassy phase content being 43%. Testing revealed a flexural strength of 125 MPa, a water absorption rate of 0.02%, a glaze thickness of 60 μm, a Vickers hardness of 8.26 GPa, and thermal stability with no cracks appearing after one heat exchange between 250℃ and 20℃. Example 3

[0034] The preparation method of a low-temperature fired self-releasing glaze feldspar daily-use ceramic according to Embodiment 3 of the present invention includes the following steps: For the ingredients, weigh out 21% kaolin, 24% quartz, 38% wollastonite, 13% potassium feldspar, 1% talc, and 3% calcined alumina by weight percentage and premix them. Weigh out 3% of the total mass of feldspar porcelain waste and crush it to a particle size ≤50μm for later use.

[0035] Ball milling: The main material and additives are fed into a ball mill, along with water (80% of the total dry weight of the raw materials) and 0.1% water glass. The mixture is then wet-milled at 400 rpm for 1 hour.

[0036] Filter the ball milling liquid through a 325-mesh sieve to obtain a uniform ball milling slurry.

[0037] Drying: Place the ball mill slurry in a dryer and dry at 110℃ for 5 hours.

[0038] The dried ball mill slurry is crushed and sieved, and then passed through a 60-mesh sieve to obtain raw material powder.

[0039] Dry pressing involves feeding raw material powder into a molding machine for dry pressing. Utilizing the natural plasticity of kaolin in the raw material, the powder can be polymerized and molded into a green body without the addition of binders.

[0040] Firing: The green ceramic blanks are placed in a kiln and fired at a rate of 5℃ / min to the peak firing temperature of 1140℃, held at that temperature for 30 minutes, and then cooled to room temperature with the kiln. The total firing cycle is 6 hours, resulting in self-releasing glaze feldspar daily-use ceramics. The main phase composition of the self-releasing glaze feldspar daily-use ceramics is quartz, anorthite, wollastonite, and a glassy phase, with a glassy phase content of 54%. Testing showed a flexural strength of 123 MPa, a water absorption rate of 0.04%, a glaze thickness of 50 μm, a Vickers hardness of 7.96 GPa, and thermal stability of no cracks after one heat exchange between 200℃ and 20℃. These results indicate... Figure 1-2 XRD patterns and SEM images.

[0041] Comparative Example 1 Comparative Example 1 is basically the same as Example 1, the main difference being that no feldspar porcelain waste was added in Comparative Example 1, resulting in ceramic products that softened and deformed. The morphological photographs of the ceramics produced in Example 1 and Comparative Example 1 are shown below. Figure 3 As shown.

[0042] Comparative Example 2 Comparative Example 2 is basically the same as Example 2, except that in the firing step, the temperature is increased to 1160°C at a rate of 5°C / min, held for 10 minutes, and then cooled to room temperature with the furnace after firing. The main phase composition of the obtained ceramic is anorthite, quartz, wollastonite, and glass phase, with a glass phase content of 64%, and the sample edges are deformed.

[0043] Comparative Example 3 Comparative Example 3 is basically the same as Example 3, except that in the firing step, the firing peak temperature is raised to 1110°C at a rate of 5°C / min and held for 120 min. The main phase composition of the obtained ceramic is quartz, anorthite, wollastonite and glass phase, and the glass phase content is 32%. The sample has no glaze layer and the surface is rough and dull.

[0044] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the inventive concept, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A low-temperature fired, self-releasing glaze feldspar daily-use ceramic, prepared by mixing main materials and additives, characterized in that: The main material comprises the following components by weight percentage: kaolin 20-30%, quartz 15-25%, wollastonite 35-40%, potassium feldspar 12-15%, talc 0-1%, and calcined alumina 0-5%; The additive is feldspar porcelain waste; The amount of the additive added is 3-5% of the total mass of the main material; The peak firing temperature of the self-releasing glaze feldspar daily-use ceramics is 1120℃~1150℃.

2. The low-temperature fired, self-releasing glaze feldspar daily-use ceramic according to claim 1, characterized in that: The phase composition of the self-releasing glaze feldspar daily ceramics after firing includes quartz, calcium feldspar, wollastonite and glass phase, with the glass phase content being 40%~55%.

3. The low-temperature fired, self-releasing glaze feldspar daily-use ceramic according to claim 1, characterized in that: The self-releasing glaze feldspar daily-use ceramic has a flexural strength >100 MPa, a water absorption rate <0.05%, and a Vickers hardness of >7.5 GPa.

4. The low-temperature fired, self-releasing glaze feldspar daily-use ceramic according to claim 1, characterized in that: The surface of the self-releasing glaze feldspar daily-use ceramic has a uniform, dense, and smooth glaze layer.

5. The low-temperature fired, self-releasing glaze feldspar daily-use ceramic according to claim 1, characterized in that, The chemical composition of the feldspar ceramic waste includes the following components by weight percentage: 65-75% silicon dioxide, 18-25% aluminum oxide, 3-7% potassium oxide, 0-1% sodium oxide, and 0.5-3% magnesium oxide.

6. A method for preparing low-temperature fired self-releasing glaze feldspar daily-use ceramics as described in any one of claims 1-5, characterized in that, Includes the following steps: For ingredient preparation, weigh and mix the main ingredients according to the ratio, and weigh and crush the additives according to the ratio to a particle size ≤50μm for later use. Ball milling involves feeding the main material and additives into a ball mill, while adding water (60% to 80% of the total dry weight of the raw materials) and water glass (0.1% to 0.5%) for wet ball milling. Filter the ball milling liquid and pass it through a 325-mesh sieve to obtain ball milling slurry; Drying: The ball mill slurry is placed in a dryer for drying. The dried ball mill slurry is crushed and ground, and then passed through a 60-mesh sieve to obtain raw material powder. Dry pressing involves feeding raw material powder into a molding machine for dry pressing to produce a green body. Firing involves placing the raw ceramic blanks into a kiln for firing at a peak temperature of 1120℃~1150℃ for 5~8 hours. After firing, the blanks are cooled to room temperature to obtain self-releasing glaze feldspar daily-use ceramics.

7. The method for preparing low-temperature fired self-releasing glaze feldspar daily-use ceramics according to claim 6, characterized in that: In the ball milling step, the ball milling speed is 400 rpm and the ball milling time is 1 h.

8. The method for preparing low-temperature fired self-releasing glaze feldspar daily-use ceramics according to claim 6, characterized in that: In the drying step, the drying temperature of the dryer is 80~120℃, and the drying time is 4~8 hours.

9. The method for preparing low-temperature fired self-releasing glaze feldspar daily-use ceramics according to claim 6, characterized in that: In the firing step, the firing process involves raising the temperature to a peak temperature of 1120℃~1150℃ at a rate of 5~10℃ / min and holding it at that temperature for 10~120 min.

Images