Preparation method of high-strength wide firing range prestressed magnesia daily-use porcelain and product prepared by the method

Abstract

The application discloses a preparation method of high-strength wide-burning-range prestressed magnesia daily-use porcelain and a product prepared by the method. A coating is introduced on the surface of a magnesia daily-use porcelain body through a coating technology, and the difference between the thermal expansion coefficients of different crystal phases is utilized, so that the thermal expansion coefficient of the surface of the body is reduced to generate a pre-compression stress, the effect of enhancing the bending strength of the body is realized, the thermal stability of the ceramic is improved, the demand problem of the magnesia daily-use porcelain for strength and thermal stability is solved, and the application has very important significance for the innovation and development of daily-use ceramic.

Description

Technical Field

[0001] This invention relates to the field of ceramic materials technology, and in particular to a method for preparing prestressed magnesia daily-use porcelain and the product obtained therefrom. Background Technology

[0002] Magnesia-based daily-use porcelain boasts advantages such as a delicate, white texture and excellent translucency. Its main crystalline phases are MgO-containing silicates or aluminates, including protoenzyme, cordierite, spinel, and forsterite. Among these, magnesia-based daily-use porcelain with protoenzyme as the main crystalline phase stands out from traditional daily-use porcelain for its tableware and teaware, making it highly sought after in both domestic and international markets. However, due to its limited firing range of only around 20℃ and the decrease in ceramic strength or even pulverization caused by the crystal transformation of protoenzyme, this type of magnesia-based daily-use porcelain lacks competitiveness in the high-end daily-use porcelain market.

[0003] In past studies, researchers have improved issues such as aging and narrow firing temperature ranges through formulation adjustments. For example, by modifying the formulation, ceramics with protoencite and cordierite as the main crystalline phases were prepared, and their firing temperature was significantly improved. However, their strength was not significantly improved, and the product quality still needs to be improved. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a method for preparing high-strength, wide-firing-range prestressed magnesia ceramics. This method involves introducing a coating onto the surface of the magnesia ceramic body using a coating technique. By utilizing the difference in thermal expansion coefficients between the two different crystalline phases, the thermal expansion coefficient of the body surface decreases, generating pre-compressive stress to address the strength and thermal stability requirements of magnesia ceramics. Another objective of this invention is to provide a product obtained using the above-described preparation method.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] This invention provides a method for preparing high-strength, wide-firing-range prestressed magnesia-based daily-use porcelain. The prestressed magnesia-based daily-use porcelain comprises a magnesia-based daily-use porcelain body, a prestress-reinforcing coating on the surface of the body, and a glaze layer on the surface of the coating. The preparation method includes the following steps:

[0007] (1) Preparation of magnesium-based daily-use ceramic blanks

[0008] The raw material composition of the magnesia-based daily-use porcelain bisque body is 55-65 wt% calcined talc, 8-20 wt% raw talc, 10-20 wt% kaolin, 0-3 wt% zinc oxide, 0-7 wt% magnesite, 5-15 wt% potassium feldspar, and 1-5 wt% barium carbonate. The raw materials are mixed and ball-milled according to this composition, and then dried, granulated, dry-pressed, and bisque-fired to obtain the magnesia-based daily-use porcelain bisque body.

[0009] (2) Preparation of prestressed reinforced coating slurry

[0010] The raw material composition of the prestressed reinforced coating slurry is 45-55 wt% calcined talc, 10-20 wt% potassium feldspar, 0-5 wt% zinc oxide, 0-5 wt% alumina, and 30-40 wt% kaolin. The raw materials are mixed according to the composition, and a 1-5 wt% polyvinyl alcohol solution is used as the ball milling medium. Tributyl phosphate is added as a defoaming agent and ball milling is performed to obtain a prestressed reinforced coating slurry with a concentration of 33-44 wt%.

[0011] (3) Preparation of magnesium-based daily-use porcelain blanks with prestressed reinforced coating

[0012] The prestress-reinforced coating slurry is uniformly coated onto the surface of the magnesia-based daily-use ceramic blank by surface coating. After drying, the magnesia-based daily-use ceramic blank coated with the coating slurry is obtained.

[0013] (4) Preparation of prestressed magnesia daily-use ceramics

[0014] The glaze is applied to the surface of the bisque-fired magnesia ceramic blank coated with the slurry, and the temperature is raised to 1250-1320℃ at 2-5℃ / min for firing. The temperature is held for 30-90 minutes and then naturally cooled to obtain high-strength, wide-firing-range prestressed magnesia ceramic.

[0015] Furthermore, in step (1) of the present invention, the pressure for dry pressing is 10-20 MPa; the bisque firing process is as follows: the temperature is increased to 600-800℃ at 2-5℃ / min and held for 30-60 min.

[0016] In the above scheme, the chemical composition of the prestressed magnesia daily-use ceramic body of the present invention is 54-57.7 wt% SiO2, 2.8-7.1 wt% Al2O3, 0.2-0.4 wt% Fe2O3, 1.96-2.76 wt% CaO, 22.1-27.9 wt% MgO, 0.6-0.9 wt% K2O, and 8.6-11.4 wt% Il. The prestressed reinforced coating in the prestressed magnesia daily-use ceramic has a thickness of 20–100 μm and a chemical composition of 57.3–64.7 wt% SiO2, 12.7–16.0 wt% Al2O3, 0.2–0.31 wt% Fe2O3, 1.5–1.8 wt% CaO, 14.5–15.87 wt% MgO, 1.2–2.0 wt% K2O, and 4.2–7.3 wt% I.L.

[0017] Further, in step (4) of the present invention, the raw material composition of the glaze is 5-10 wt% calcined talc, 25-35 wt% potassium feldspar, 0-5 wt% zinc oxide, 0-5 wt% barium carbonate, 5-15 wt% kaolin, 20-30 wt% calcite, and 20-30 wt% quartz. The thickness of the glaze layer in the prestressed magnesia daily-use ceramic is 200-300 μm, and the chemical composition of the glaze layer is 53.1-57.3 wt% SiO2, 8.4-11.3 wt% Al2O3, 0.06-0.12 wt% Fe2O3, 11.3-14.1 wt% CaO, 1.6-2.5 wt% MgO, 1.9-3.3 wt% K2O, and 13.8-18.7 wt% Il.

[0018] Another objective of this invention is achieved through the following technical solution:

[0019] The product prepared by the above-mentioned method for producing high-strength, wide-firing-range prestressed magnesia daily-use ceramics provided by this invention has the following characteristics: the main crystalline phase of the prestressed magnesia daily-use ceramic body is protoencite, and the coefficient of thermal expansion of the prestressed magnesia ceramic body is 7.5 × 10⁻⁶. -6 ~8.5×10 -6 / ℃; the main crystalline phase of the prestressed reinforced coating is cordierite, and the coefficient of thermal expansion of the coating is 4.6×10. -6 ~6.6×10 -6 / ℃.

[0020] Furthermore, the fracture toughness of the prestressed magnesia-based daily-use ceramic of the present invention is 2.54–2.78 MPa·m. 1 / 2 The bending strength is 240-275 MPa, and the thermal stability is 250-20℃ without cracking after a single rapid cooling.

[0021] The present invention has the following beneficial effects:

[0022] (1) The high-strength, wide-sintering-range prestressed magnesia daily-use porcelain provided by the present invention can solve the problem of narrow sintering range of magnesia daily-use porcelain by designing the body formula, and broaden its sintering range to 40-70℃.

[0023] (2) The prestressed magnesia daily-use porcelain provided by this invention produces a crystal phase composition consisting mainly of protoencite, accompanied by a small amount of clinoptilolite and enstatite, during the high-temperature firing process. Its coefficient of thermal expansion is 7.5 × 10⁻⁶. -6 ~8.5×10 -6 / ℃; By changing the raw material ratio, cordierite was synthesized during the high-temperature firing process of the coating. Due to the formation of cordierite with a reduced coefficient of thermal expansion, the coefficient of thermal expansion of the surface coating is reduced, and compressive stress is formed on the surface of the body, thereby enhancing the flexural strength of the body and improving the thermal stability of the ceramic. This method solves the requirements of magnesia-based daily-use ceramics for strength and thermal stability.

[0024] (3) This invention combines and designs two different magnesium ceramic main crystal phases, which effectively increases the quality and performance of magnesium daily necessities and is of great significance to the innovation and development of daily necessities ceramics. Attached Figure Description

[0025] The present invention will now be described in further detail with reference to the embodiments and accompanying drawings:

[0026] Figure 1 This is an XRD pattern of the magnesium-based daily-use porcelain blank obtained in an embodiment of the present invention;

[0027] Figure 2 This is an XRD pattern of the prestress-reinforced coating of the magnesium-based daily-use ceramic prepared according to an embodiment of the present invention;

[0028] Figure 3 This is a SEM image of the cross-section of the magnesium-based daily-use porcelain obtained in an embodiment of the present invention. Detailed Implementation

[0029] Example 1:

[0030] This embodiment discloses a method for preparing high-strength, wide-firing-range prestressed magnesia-based daily-use porcelain. The prestressed magnesia-based daily-use porcelain consists of a magnesia-based daily-use porcelain body, a prestress-reinforcing coating on the surface of the body, and a glaze layer on the surface of the coating. The preparation method includes the following steps:

[0031] (1) Preparation of magnesium-based daily-use ceramic blanks

[0032] The raw material composition of the magnesia-based daily-use porcelain bisque body is 60wt% calcined talc, 10wt% raw talc, 15wt% kaolin, 2wt% zinc oxide, 4wt% magnesite, 6wt% potassium feldspar, and 3wt% barium carbonate. The raw materials are prepared according to this composition and ball-milled with water as the ball milling medium for 12 hours. The resulting slurry is dried in an 80℃ drying oven for 12 hours. After grinding, granulation, and passing through a 60-mesh sieve, the powder is dry-pressed under a pressure of 20MPa and then bisque-fired at 650℃ at a rate of 5℃ / min for 30 minutes to obtain the magnesia-based daily-use porcelain bisque body.

[0033] (2) Preparation of prestressed reinforced coating slurry

[0034] The raw material composition of the prestressed reinforced coating slurry is 46 wt% calcined talc, 13 wt% potassium feldspar, 4 wt% zinc oxide, 3 wt% alumina, and 34 wt% kaolin. The raw materials are mixed according to this composition. A 1 wt% polyvinyl alcohol solution is used as the ball milling medium. Tributyl phosphate is added as a defoaming agent and ball milling is performed to obtain a prestressed reinforced coating slurry with a concentration of 40 wt%.

[0035] (3) Preparation of magnesium-based daily-use porcelain blanks with prestressed reinforced coating

[0036] The above-mentioned prestress-reinforced coating slurry is uniformly coated on the surface of the above-mentioned magnesia-based daily-use ceramic blank by means of surface coating. After drying, a magnesia-based daily-use ceramic blank coated with coating slurry is obtained.

[0037] (4) Preparation of prestressed magnesia daily-use ceramics

[0038] The raw material composition of the glaze is 6wt% calcined talc, 32wt% potassium feldspar, 4wt% zinc oxide, 2wt% barium carbonate, 11wt% kaolin, 23wt% calcite, and 22wt% quartz. The raw materials are mixed according to this composition and ball-milled with water as the ball milling medium for 2 hours. The glaze slurry obtained after passing through a 250-mesh sieve is applied to the surface of the magnesia daily-use ceramic blank coated with the glaze slurry by spraying. The blank is then fired at 1260℃ at a rate of 5℃ / min, held for 60 minutes, and then naturally cooled to obtain high-strength, wide-firing-range prestressed magnesia daily-use ceramic.

[0039] The prestressed magnesia-based daily-use porcelain prepared in this embodiment has the following chemical composition: Body composition: SiO2 54.87 wt%, Al2O3 6.52 wt%, Fe2O3 0.27 wt%, CaO 2.39 wt%, MgO 24.66 wt%, K2O 0.77 wt%, I.L 10.52 wt%; Coating composition: SiO2 60.09 wt%, Al2O3 15.21 wt%, Fe2O3 0.31 wt%, CaO 1.73 wt%, MgO 15.87 wt%, K2O 1.66 wt%, I.L 5.13 wt%; Glaze composition: SiO2 55.50 wt%, Al2O3 9.30 wt%, Fe2O3 0.10 wt%, CaO 13.25 wt%, MgO 1.94 wt%, K2O 3.07 wt%, I.L 10.52 wt%; Coating composition: ... 16.84 wt%.

[0040] Example 2:

[0041] This embodiment discloses a method for preparing high-strength, wide-firing-range prestressed magnesia-based daily-use porcelain. The prestressed magnesia-based daily-use porcelain consists of a magnesia-based daily-use porcelain body, a prestress-reinforcing coating on the surface of the body, and a glaze layer on the surface of the coating. The preparation method includes the following steps:

[0042] (1) Preparation of magnesium-based daily-use ceramic blanks

[0043] The raw material composition of the magnesia-based daily-use porcelain bisque body is 60wt% calcined talc, 10wt% raw talc, 15wt% kaolin, 2wt% zinc oxide, 4wt% magnesite, 6wt% potassium feldspar, and 3wt% barium carbonate. The raw materials are prepared according to this composition and ball-milled with water as the ball milling medium for 12 hours. The resulting slurry is dried in an 80℃ drying oven for 12 hours. After grinding, granulation, and passing through a 60-mesh sieve, the powder is dry-pressed under a pressure of 20MPa and then bisque-fired at 700℃ at a rate of 5℃ / min for 30 minutes to obtain the magnesia-based daily-use porcelain bisque body.

[0044] (2) Preparation of prestressed reinforced coating slurry

[0045] The raw material composition of the prestressed reinforced coating slurry is 46 wt% calcined talc, 12 wt% potassium feldspar, 3 wt% zinc oxide, 4 wt% alumina, and 35 wt% kaolin. The raw materials are mixed according to this composition. A 1 wt% polyvinyl alcohol solution is used as the ball milling medium. Tributyl phosphate is added as a defoaming agent and the mixture is ball-milled to obtain a prestressed reinforced coating slurry with a concentration of 35 wt%.

[0046] (3) Preparation of magnesium-based daily-use porcelain blanks with prestressed reinforced coating

[0047] The above-mentioned prestress-reinforced coating slurry is uniformly coated on the surface of the above-mentioned magnesia-based daily-use ceramic blank by means of surface coating. After drying, a magnesia-based daily-use ceramic blank coated with coating slurry is obtained.

[0048] (4) Preparation of prestressed magnesia daily-use ceramics

[0049] The raw material composition of the glaze is 6wt% calcined talc, 32wt% potassium feldspar, 4wt% zinc oxide, 2wt% barium carbonate, 11wt% kaolin, 23wt% calcite, and 22wt% quartz. The raw materials are mixed according to this composition and ball-milled for 12 hours with water as the ball milling medium. The glaze slurry obtained after passing through a 250-mesh sieve is applied to the surface of the magnesia daily-use ceramic blank coated with the glaze slurry by spraying. The blank is then fired at 1260℃ at a rate of 5℃ / min, held for 60 minutes, and then naturally cooled to obtain high-strength prestressed magnesia daily-use ceramic with a wide firing range.

[0050] The prestressed magnesia-based daily-use porcelain prepared in this embodiment has the following chemical composition: Body composition: SiO2 54.87 wt%, Al2O3 6.52 wt%, Fe2O3 0.27 wt%, CaO 2.39 wt%, MgO 24.66 wt%, K2O 0.77 wt%, I.L 10.52 wt%; Coating composition: SiO2 59.78 wt%, Al2O3 15.62 wt%, Fe2O3 0.3 wt%, CaO 1.61 wt%, MgO 14.89 wt%, K2O 1.49 wt%, I.L 6.31 wt%; Glaze composition: SiO2 55.50 wt%, Al2O3 9.30 wt%, Fe2O3 0.10 wt%, CaO 13.25 wt%, MgO 1.94 wt%, K2O 3.07 wt%, I.L 10.52 wt%; Coating composition: ... 16.84 wt%.

[0051] Example 3:

[0052] This embodiment discloses a method for preparing high-strength, wide-firing-range prestressed magnesia-based daily-use porcelain. The prestressed magnesia-based daily-use porcelain consists of a magnesia-based daily-use porcelain body, a prestress-reinforcing coating on the surface of the body, and a glaze layer on the surface of the coating. The preparation method includes the following steps:

[0053] (1) Preparation of magnesium-based daily-use ceramic blanks

[0054] The raw material composition of the magnesia-based daily-use porcelain bisque body is 60wt% calcined talc, 10wt% raw talc, 15wt% kaolin, 2wt% zinc oxide, 4wt% magnesite, 6wt% potassium feldspar, and 3wt% barium carbonate. The raw materials are prepared according to this composition and ball-milled with water as the ball milling medium for 12 hours. The resulting slurry is dried in an 80℃ drying oven for 12 hours. After grinding, granulation, and passing through a 60-mesh sieve, the powder is dry-pressed under a pressure of 20MPa and then bisque-fired at 750℃ at a rate of 5℃ / min for 30 minutes to obtain the magnesia-based daily-use porcelain bisque body.

[0055] (2) Preparation of prestressed reinforced coating slurry

[0056] The raw material composition of the prestressed reinforced coating slurry is 49 wt% calcined talc, 15 wt% potassium feldspar, 3 wt% zinc oxide, 2 wt% alumina, and 31 wt% kaolin. The raw materials are mixed according to this composition. A 1 wt% polyvinyl alcohol solution is used as the ball milling medium. Tributyl phosphate is added as a defoaming agent and ball milling is performed to obtain a prestressed reinforced coating slurry with a concentration of 42 wt%.

[0057] (3) Preparation of magnesium-based daily-use porcelain blanks with prestressed reinforced coating

[0058] The above-mentioned prestress-reinforced coating slurry is uniformly coated on the surface of the above-mentioned magnesia-based daily-use ceramic blank by means of surface coating. After drying, a magnesia-based daily-use ceramic blank coated with coating slurry is obtained.

[0059] (4) Preparation of prestressed magnesia daily-use ceramics

[0060] The raw material composition of the glaze is 6wt% calcined talc, 32wt% potassium feldspar, 4wt% zinc oxide, 2wt% barium carbonate, 11wt% kaolin, 23wt% calcite, and 22wt% quartz. The raw materials are mixed according to this composition and ball-milled for 12 hours with water as the ball milling medium. The glaze slurry obtained after passing through a 250-mesh sieve is applied to the surface of the magnesia daily-use ceramic blank coated with the glaze slurry by spraying. The blank is then fired at 1300℃ at a rate of 5℃ / min, held for 60 minutes, and then naturally cooled to obtain high-strength, wide-firing-range prestressed magnesia daily-use ceramic.

[0061] The prestressed magnesia-based daily-use porcelain prepared in this embodiment has the following chemical composition: Body composition: SiO2 54.87 wt%, Al2O3 6.52 wt%, Fe2O3 0.27 wt%, CaO 2.39 wt%, MgO 24.66 wt%, K2O 0.77 wt%, I.L 10.52 wt%; Coating composition: SiO2 59.09 wt%, Al2O3 15.5 wt%, Fe2O3 0.29 wt%, CaO 1.64 wt%, MgO 14.95 wt%, K2O 1.8 wt%, I.L 6.73 wt%; Glaze composition: SiO2 55.50 wt%, Al2O3 9.30 wt%, Fe2O3 0.10 wt%, CaO 13.25 wt%, MgO 1.94wt%, K2O3.07wt%, I.L16.84wt%.

[0062] The high-strength, wide-firing-range prestressed magnesia daily-use ceramics prepared in this embodiment of the invention have a water absorption rate of less than 0.5%. The green body is dominated by protoencronite as the main crystalline phase, with a small amount of clinoptilolite and enstatite (see...). Figure 1 The prestressed reinforced coating is mainly composed of cordierite. For example... Figure 3 As shown, the glaze, prestressed reinforcing coating, and body are tightly bonded together. The thickness of the glaze is 200–300 μm, and the thickness of the prestressed reinforcing coating is 20–100 μm. The performance indicators of magnesia-based daily-use ceramics are shown in Table 1.

[0063] Table 1 Performance indicators of prestressed magnesia-based daily-use ceramics prepared according to the embodiments of the present invention.

[0064]

Claims

1. A method for preparing high-strength, wide-firing-range prestressed magnesia daily-use porcelain, characterized in that: The prestressed magnesia ceramic for daily use consists of a magnesia ceramic body, a prestressed reinforcing coating on the surface of the body, and a glaze layer on the surface of the coating; the fracture toughness of the prestressed magnesia ceramic for daily use is 2.54–2.78 MPa·m. 1 / 2 The flexural strength is 254.05–275 MPa, and the thermal stability is 250–20℃ without cracking after a single rapid cooling. The preparation method includes the following steps: (1) Preparation of magnesia-based daily-use porcelain blanks The raw material composition of the magnesia-based daily-use porcelain bisque body is 55-65 wt% calcined talc, 8-20 wt% raw talc, 10-20 wt% kaolin, 2-3 wt% zinc oxide, 4-7 wt% magnesite, 5-15 wt% potassium feldspar, and 1-5 wt% barium carbonate. The raw materials are mixed and ball-milled according to this composition, and then dried, granulated, dry-pressed, and bisque-fired to obtain the magnesia-based daily-use porcelain bisque body. (2) Preparation of prestressed reinforced coating slurry The raw material composition of the prestressed reinforced coating slurry is 45-55 wt% calcined talc, 10-20 wt% potassium feldspar, 3-5 wt% zinc oxide, 2-5 wt% alumina, and 30-40 wt% kaolin. The raw materials are mixed according to this composition, and a 1-5 wt% polyvinyl alcohol solution is used as the ball milling medium. Tributyl phosphate is added as a defoaming agent and ball milling is performed to obtain a prestressed reinforced coating slurry with a concentration of 33-44 wt%. (3) Preparation of magnesium-based daily-use porcelain blanks with prestressed reinforced coating The prestress-reinforced coating slurry is uniformly coated onto the surface of the magnesia-based daily-use ceramic blank by surface coating. After drying, the magnesia-based daily-use ceramic blank coated with the coating slurry is obtained. (4) Preparation of prestressed magnesia daily-use ceramics The glaze is composed of 5-10 wt% calcined talc, 25-35 wt% potassium feldspar, 4-5 wt% zinc oxide, 2-5 wt% barium carbonate, 5-15 wt% kaolin, 20-30 wt% calcite, and 20-30 wt% quartz. The glaze is applied to the surface of a bisque-fired magnesia ceramic body coated with the glaze slurry, and fired at 1250-1320℃ with a heating rate of 2-5℃ / min, held for 30-90 min, and then naturally cooled to obtain a high-strength, wide-firing-range prestressed magnesia ceramic body. The main crystalline phase of the body is protoenzyme, and the coefficient of thermal expansion is 7.5 × 10⁻⁶. -6 ~8.5×10 -6 The chemical composition of the preform at / ℃ is SiO2 54–57.7 wt%, Al2O3 2.8–7.1 wt%, Fe2O3 0.2–0.4 wt%, CaO 1.96–2.76 wt%, MgO 22.1–27.9 wt%, K2O 0.6–0.9 wt%, and IL 8.6–11.4 wt%. The coating thickness is 20–100 μm, its main crystalline phase is cordierite, and its coefficient of thermal expansion is 4.6 × 10⁻⁶. -6 ~6.6×10 -6 The coating has a chemical composition of SiO2 57.3–64.7 wt%, Al2O3 12.7–16.0 wt%, Fe2O3 0.2–0.31 wt%, CaO 1.5–1.8 wt%, MgO 14.5–15.87 wt%, K2O 1.2–2.0 wt%, and IL 4.2–7.3 wt% at a temperature of / ℃. The glaze layer has a thickness of 200–300 μm and a chemical composition of SiO2 53.1–57.3 wt%, Al2O3 8.4–11.3 wt%, Fe2O3 0.06–0.12 wt%, CaO 11.3–14.1 wt%, MgO 1.6–2.5 wt%, K2O 1.9–3.3 wt%, and IL 13.8–18.7 wt%.

2. The method for preparing high-strength, wide-firing-range prestressed magnesia daily-use porcelain according to claim 1, characterized in that: The pressure for dry pressing in step (1) is 10-20 MPa; the firing process is as follows: the temperature is increased to 600-800℃ at 2-5℃ / min and held for 30-60 min.

3. The product obtained by the preparation method of high-strength, wide-firing-range prestressed magnesia daily-use porcelain as described in claim 1 or 2.

Images