Preparation method of imitated chemical tempered ceramic product and ceramic product thereof

Abstract

The invention discloses a preparation method of an imitated chemical tempered ceramic product and the ceramic product thereof, an expansion irreversible material is added on the surface layer of a ceramic green body, so that surface compressive stress is formed by expansion of a surface layer material and no or little expansion of the green body in a cooling process, and the surface compressive stress is similar to that of chemically tempered glass; the shrinkage of the ceramic body is partially or completely counteracted by simulating the pinning effect, so that the breaking strength of the ceramic is remarkably improved, the applicability is high, and the thermal shock damage in the molten salt treatment process in the prior art is also avoided. The preparation and application production are simple and easy to control, the cost is low, the preparation of the thin-body ceramic is facilitated, the usage amount of raw materials for producing the green body can be reduced, high-quality ceramic raw material resources are saved, the production cost is reduced, energy conservation and emission reduction are facilitated, and the method has a good application prospect for sustainable development of the ceramic industry. And the method plays an important role in accelerating ecological civilization construction and realizing green development, and has very high practical value and application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of ceramic materials, and particularly relates to a preparation method of a chemically strengthened ceramic imitation product and the ceramic product thereof. Background Art

[0002] Tempered glass (also known as prestressed glass) is ordinary glass that has been processed in a certain way to form compressive stress on the glass surface to effectively prevent the expansion of microcracks on the surface and partially or completely offset the tensile stress caused by an applied load, thereby improving the mechanical strength, stability, and safety of the glass. Among them, physical tempered glass is to heat ordinary glass to the softening temperature (650 - 800 °C) and then rapidly cool it in a cooling medium (gas, liquid, etc.). Since the surface of the molten glass immediately cools and becomes rigid with a small shrinkage rate, while the interior is still in a molten state, the shrinkage during the subsequent cooling process causes compressive residual stress to be generated on the hardened glass surface. This physical tempered glass was not widely used until more than 30 years after its first invention. The chemical tempering method (also known as the ion exchange method) is to change the composition of the glass surface through a chemical method. Specifically, large-radius alkali metal ions (such as K + with a radius of 1.33 Å) in a molten salt are used to replace small-radius ions (such as Na + with a radius of 0.98 Å) on the glass surface. After cooling, the large ions are squeezed to form a pinning effect on the surface layer, providing compressive stress to the glass surface, thereby improving the strength, thermal stability, and safety performance of the glass.

[0003] Tempered glass has been widely recognized by the world, but prestressed ceramics, which are also traditional silicate materials, are not as well-known as tempered glass. Generally speaking, there are usually two modes for the formation of compressive stress on the material surface layer: one is that during the shrinkage process, the surface layer shrinks less than the matrix, so it is pulled by the shrinkage of the matrix to form compressive stress on the surface layer, similar to physical tempered glass; the second is that the surface layer expands while the matrix expands little or not at all, causing compressive stress to be generated on the surface layer, similar to chemical tempered glass. In recent years, most of the existing technologies are to prepare tempered ceramics by coating a low-expansion and shrinkage wrapping-type compact constraint compressive stress tempered coating on the matrix surface (similar to physical tempered glass) to achieve the purpose of simultaneously improving the strength and damage tolerance of ceramics. The method of simulating chemically tempered glass (similar to chemically tempered glass) has a certain strengthening effect on ceramics containing a glass phase on the surface, but the scope of application is limited, and the molten salt treatment process will cause damage to the ceramic surface. Summary of the Invention

[0004] The object of the present invention is to overcome the deficiencies of the prior art and provide a preparation method for chemically strengthened ceramic products. By adding an irreversible expansion material to the surface layer of the ceramic green body, surface compressive stress is formed during the cooling process due to the expansion of the surface layer material while the green body expands little or not at all, similar to chemically strengthened glass. By simulating the pinning effect, the shrinkage of the ceramic green body is partially or completely offset to improve the flexural strength of the ceramic and avoid the thermal shock damage during the molten salt treatment process in the prior art. Another object of the present invention is to provide a ceramic product prepared by using the above preparation method for chemically strengthened ceramic products.

[0005] The object of the present invention is achieved by the following technical solutions:

[0006] A preparation method for chemically strengthened ceramic products provided by the present invention, the ceramic products are composed of a ceramic green body and irreversible expansion material layers located on the upper and lower surfaces of the ceramic green body; the preparation method includes the following steps:

[0007] (1) Prepare the irreversible expansion material powder

[0008] Using andalusite, sillimanite, kyanite or a combination thereof as raw materials, after ball milling, sieving, and drying, the irreversible expansion material powder is obtained;

[0009] (2) Prepare the ceramic green body mud

[0010] After the raw material composition of the ceramic green body is wet ball milled, iron removed by sieving, vacuum pugged, and aged, the ceramic green body mud is obtained;

[0011] (3) Prepare the chemically strengthened ceramic green body

[0012] Evenly lay the lower irreversible expansion material powder, the middle ceramic green body mud, and the upper irreversible expansion material powder in sequence from bottom to top in a plastic molding mold; the amounts of the upper irreversible expansion material powder and the lower irreversible expansion material powder are the same, and the total amount of the irreversible expansion material powder is 10-15 wt% of the ceramic green body mud. After molding, a green body with a water content of 22-25% is obtained and subjected to biscuit firing at a temperature of 600-850 °C. After cooling, the chemically strengthened ceramic green body is obtained;

[0013] (3) Prepare the chemically strengthened ceramic products

[0014] Sinter the chemically strengthened ceramic green body at a temperature of 1350-1450 °C, with a heating rate of 3-5 °C / min and a holding time of 25-35 min, and naturally cool to room temperature to obtain the chemically strengthened ceramic products.

[0015] Further, the raw material composition of the ceramic green body of the present invention is 40-60 wt% kaolinite, 20-30 wt% quartz, and 20-30 wt% feldspar. The particle size of the irreversible expansion material powder is 50-150 mesh.

[0016] In the above solution, in step (2) of the present invention, wet ball milling is carried out according to the ratio of material: ball: water = 1:2:0.4-0.6; the aging time is 15-18 h.

[0017] The ceramic product prepared by using the preparation method of the chemical toughening imitation ceramic product.

[0018] The present invention has the following beneficial effects:

[0019] (1) In the present invention, an irreversible expansion material is added to the surface of the ceramic green body to offset the shrinkage of the ceramic green body. During the cooling process, the expansion of the ceramic surface layer is greater than that of the matrix, so that the surface layer is pulled by the shrinkage of the matrix to form a surface compressive stress, similar to chemically toughened glass, achieving the purpose of significantly improving the flexural strength of the green body (the improvement rate is more than 40%), and having strong applicability, and also avoiding the thermal shock damage in the molten salt treatment process of the prior art.

[0020] (2) The present invention is helpful for the preparation of thin-walled ceramics (less than 0.5 mm). It can not only reduce the usage amount of raw materials for producing the green body, save high-quality ceramic raw material resources, reduce production costs, but also be beneficial to energy conservation and emission reduction, thus playing an important role in the sustainable development of the ceramic industry, accelerating the construction of ecological civilization, and realizing green development.

[0021] (3) The preparation and application of the present invention are simple and easy to control, with low cost. It can use the existing mature ceramic production equipment and process technology, which is helpful for popularization and application, and has high practical value and application prospects.

[0022] The present invention will be further described in detail below in conjunction with embodiments. Specific embodiments

[0023] An embodiment of the present invention provides a preparation method of a chemical toughening imitation ceramic product. The ceramic product is composed of a ceramic green body and irreversible expansion material layers located on the upper and lower surfaces of the ceramic green body; the preparation method comprises the following steps:

[0024] (1) Prepare the irreversible expansion material powder

[0025] Using andalusite, sillimanite, kyanite or a combination thereof as raw materials, after ball milling, sieving, drying and granulating, an irreversible expansion material powder with a particle size of 50-150 mesh is obtained; the raw material composition and powder particle size of the irreversible expansion material powder in each embodiment are shown in Table 1;

[0026] (2) Prepare the ceramic green body mud

[0027] Weigh the raw materials of the ceramic green body according to the composition: kaolinite 40 - 60 wt%, quartz 20 - 30 wt%, feldspar 20 - 30 wt%. Conduct wet ball milling treatment according to the ratio of material : ball : water = 1 : 2 : 0.4 - 0.6. After screening out iron, vacuum pugging, and aging for 15 - 18 h, obtain the ceramic green body mud.

[0028] (3) Prepare the chemically strengthened ceramic green body

[0029] Uniformly lay the lower layer of irreversible expansion material powder, the middle layer of ceramic green body mud, and the upper layer of irreversible expansion material powder in sequence from bottom to top in a plastic forming mold; the dosage of the upper layer of irreversible expansion material powder is the same as that of the lower layer, and the total dosage of the irreversible expansion material powder is 10 - 15 wt% of the ceramic green body mud. After forming, obtain a green body with a moisture content of 22 - 25%, and conduct biscuit firing at a temperature of 600 - 850 °C. After cooling, obtain the chemically strengthened ceramic green body.

[0030] (3) Prepare the chemically strengthened ceramic products

[0031] Sinter the above chemically strengthened ceramic green body at a temperature of 1350 - 1450 °C, with a heating rate of 3 - 5 °C / min and a holding time of 25 - 35 min. Naturally cool to room temperature to obtain the chemically strengthened ceramic products.

[0032] The process parameters of the preparation methods of the chemically strengthened ceramic products in each example are shown in Table 2.

[0033] Table 1 Raw material composition and powder particle size of the irreversible expansion material powder in each example of the present invention

[0034]

[0035]

[0036] * According to the mass ratio, andalusite : kyanite = 1 : 1

[0037] ** According to the mass ratio, kyanite : sillimanite = 4 : 1

[0038] Table 2 Process parameters of the preparation methods of the chemically strengthened ceramic products in each example of the present invention

[0039]

[0040] * It is the weight percentage of the ceramic green body mud.

[0041] The ceramic products of each embodiment of the present invention that do not use the irreversible expansion material are used as the corresponding comparative examples. The flexural strengths of the chemically strengthened ceramic products prepared in each embodiment of the present invention and the products obtained in the corresponding comparative examples are shown in Table 3.

[0042] Table 3 Flexural strengths of the ceramic products prepared in each embodiment of the present invention and the comparative examples

[0043]

Claims

1. A preparation method of a chemically strengthened ceramic product imitation, characterized in that: The ceramic product is composed of a ceramic green body and irreversible expansion material layers located on the upper and lower surfaces of the ceramic green body; the preparation method includes the following steps: (1) Prepare the irreversible expansion material powder Using andalusite, sillimanite, kyanite or a combination thereof as raw materials, after ball milling, sieving and drying, the irreversible expansion material powder is obtained; (2) Prepare the ceramic green body mud After the raw material composition of the ceramic green body is subjected to wet ball milling, iron removal by sieving, vacuum pugging and aging, the ceramic green body mud is obtained; (3) Prepare the chemically strengthened imitation ceramic green body Uniformly lay the lower irreversible expansion material powder, the middle ceramic green body mud and the upper irreversible expansion material powder from bottom to top in a plastic forming mold; the upper irreversible expansion material powder and the lower irreversible expansion material powder have the same dosage, and the total dosage of the irreversible expansion material powder is 10-15wt% of the ceramic green body mud. After forming, a green body with a moisture content of 22-25% is obtained. After being subjected to biscuit firing at a temperature of 600-850°C and cooled, the chemically strengthened imitation ceramic green body is obtained; (3) Prepare the chemically strengthened imitation ceramic product Sinter the chemically strengthened imitation ceramic green body at a temperature of 1350-1450°C, with a heating rate of 3-5°C / min and a holding time of 25-35min, and cool it naturally to room temperature, then the chemically strengthened imitation ceramic product is obtained.

2. The preparation method of the chemically strengthened ceramic product according to claim 1, wherein: The raw material composition of the ceramic green body is 40-60wt% kaolinite, 20-30wt% quartz and 20-30wt% feldspar.

3. The preparation method of the chemically strengthened ceramic product according to claim 1, characterized in that: The particle size of the irreversible expansion material powder is 50-150 mesh.

4. The preparation method of the chemically strengthened ceramic product imitation according to claim 1, characterized in that: In the step (2), wet ball milling is carried out according to the ratio of material:ball:water = 1:2:0.4-0.6; the aging time is 15-18h.

5. A ceramic product prepared by the preparation method of the chemically strengthened imitation ceramic product according to any one of claims 1-4.

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