A kind of bone china with high thermal shock resistance and its preparation method

Abstract

This application belongs to the field of ceramic preparation, and particularly relates to a high thermal shock resistant bone china and a preparation method thereof. In order to solve the problem of insufficient thermal shock resistance of bone china in the prior art, this application provides a high thermal shock resistant bone china and a preparation method thereof, which adopts a three-layer gradient structure design, including a matrix layer, an intermediate transition layer and a surface dense layer. The matrix layer contains hydroxyapatite, bone ash, modified palygorskite, flux and kaolin. The intermediate transition layer uses anorthite and β-tricalcium phosphate. The surface dense layer is composed of ZrO2 and SiO2. By segmental sintering and laser treatment to optimize the structure, the thermal stress concentration is significantly reduced, and at the same time, excellent mechanical strength is ensured.

Description

Technical Field

[0001] This application belongs to the field of ceramic preparation, and particularly relates to a high thermal shock resistant bone china and its preparation method. Background Art

[0002] Bone china is a ceramic material with bone meal as the core raw material. Its preparation process forms a unique microstructure through the synergistic effect of bone meal and mineral raw materials such as kaolin, quartz, and feldspar. Bone china is known for its high whiteness, excellent light transmittance, high mechanical strength, and good chemical stability. The low-lead or lead-free characteristic of its surface glaze layer further enhances its safety, making it a high-end material in the fields of tableware, ornaments, etc.

[0003] However, the bone china has significant defects in thermal shock resistance. This problem stems from its microstructural and thermophysical characteristics. The coexistence of tricalcium phosphate and glass phase in bone china results in a relatively low thermal expansion coefficient, and the difference in thermal expansion coefficient between the crystal phase and the glass phase exacerbates the uneven distribution of internal stress during temperature changes. When bone china undergoes rapid heating and cooling, the temperature difference between the surface and the interior induces non-uniform thermal strain, leading to the concentration of tensile stress at grain boundaries or microcracks. If this stress exceeds the strength limit of the material, it will cause crack propagation and ultimately lead to breakage. In addition, the organic components in bone meal may chemically react with the glaze at high temperatures, further weakening the structural stability. Therefore, bone china is prone to cracking or breakage when subjected to severe temperature differences, which limits its application in scenarios such as cooking utensils that require tolerance to extreme temperature changes.

[0004] To address the problem of insufficient thermal shock resistance, the prior art has attempted to improve the preparation process of bone china through various means. Traditional methods include precisely controlling the ratios of bone meal, kaolin, feldspar, and quartz, and optimizing the sintering temperature and atmosphere conditions to balance the density and toughness of the microstructure. Some studies have introduced nano-scale reinforcing phases such as zirconia, silicon carbide, or low thermal expansion coefficient materials such as spodumene and cordierite, attempting to reduce thermal stress by regulating the thermal expansion coefficient and elastic modulus. For example, by adding 3Y-ZrO2 particles, using the microcracks induced by its phase transformation to dissipate stress; or by introducing datolite to supplement the calcium source and introducing boron and lithium oxide to enhance the thermal stability. Summary of the Invention

[0005] To solve the problem of insufficient thermal shock resistance of bone china in the prior art, this application provides a high thermal shock resistant bone china and its preparation method, which adopts a three-layer gradient structure design, including a matrix layer, an intermediate transition layer, and a surface dense layer. This bone china has excellent thermal shock resistance while maintaining good mechanical strength.

[0006] ]This application provides a high thermal shock resistant bone china, which sequentially includes a matrix layer, an intermediate transition layer, and a surface dense layer;

[0007] The matrix layer comprises the following substances by weight percentage: 25-45% hydroxyapatite, 20-30% bone ash, 3-8% modified palygorskite, 6-15% flux, and 20-35% kaolin;

[0008] The intermediate transition layer comprises the following substances by weight percentage: 55-60% anorthite, 35-45% β-tricalcium phosphate, and 0.6-2% pore-forming agent;

[0009] The surface dense layer comprises the following substances by weight percentage: 30-40% ZrO2, 60-70% SiO2.

[0010] Furthermore, the flux is one or both of lithium carbonate and magnesium oxide, and the pore-forming agent is ammonium carbonate.

[0011] This application provides a preparation method of high thermal shock resistance bone china:

[0012] S1. Mix palygorskite with hydrochloric acid solution, react at 60-90 °C for 3-8 hours, after centrifugal washing, place it in an Mg 2+ solution at 800-1200 ppm, react at 100-120 °C for 36-60 hours, and obtain modified palygorskite after drying;

[0013] S2. Mix hydroxyapatite, bone ash, the modified palygorskite obtained in S1, flux, and kaolin, then ball mill, carry out slip casting to obtain a wet blank of the matrix layer, and then deposit the intermediate transition layer on the surface of the matrix layer by electrostatic spraying of anorthite, β-tricalcium phosphate, and pore-forming agent, and finally spin-coat a suspension of nano-ZrO2 and SiO2 to obtain the surface dense layer;

[0014] S3. Sinter the blank obtained in S2 in segments, heat it to 750-850 °C at a rate of 3-8 °C / min in a nitrogen atmosphere, hold for 20-40 min; heat it to 1100-1200 °C at a rate of 0.5-2 °C / min, hold for 20-40 min, and then cool to room temperature;

[0015] S4. Carry out laser surface treatment on the surface dense layer, with a power of 500-700 W, a scanning speed of 2-5 mm / s, and a spot diameter of 0.3-0.7 mm.

[0016] Furthermore, the particle size of the palygorskite in step S1 is <1 μm, the concentration of the hydrochloric acid solution is 4.5-5.5 mol / L, and the solid-liquid mass ratio of palygorskite to hydrochloric acid solution is 1:180-220.

[0017] Furthermore, the pH of the Mg 2+ solution in step S1 is adjusted to 8.5-9.5 with sodium hydroxide solution.

[0018] Furthermore, the hydroxyapatite, bone ash, modified palygorskite obtained in S1, flux, and kaolin described in step S2 are ball-milled to a D50 of 1.5 - 2.5 μm.

[0019] Furthermore, the pressure for slip casting in step S2 is 0.3 - 0.7 MPa, and the thickness of the green body is 6 - 10 mm.

[0020] Furthermore, the electrostatic spraying voltage in step S2 is 40 - 60 kV, and the thickness of the intermediate transition layer is 0.4 - 0.6 mm.

[0021] Furthermore, for the laser surface treatment in step S4, the laser wavelength is 1064 nm, the pulse width is 10 ns, the power is 500 - 800 W, the spot diameter is 0.3 - 0.7 mm, and the scanning speed is 2 - 5 mm / s.

[0022] Through innovative multi-layer gradient structure design and component optimization, this application solves the problem of insufficient thermal shock resistance in existing bone china. First, in the design of the matrix layer, a combination of hydroxyapatite, bone ash, modified palygorskite, flux, and kaolin is used. Hydroxyapatite, as a component of bone china, has excellent properties, but its brittleness is relatively high. To address this issue, the applicant significantly improves its mechanical properties through the compounding of modified palygorskite and flux. After acid activation and magnesium ion modification, the layered structure of modified palygorskite can effectively absorb thermal stress and improve fracture toughness. This bridging effect or interface blocking crack propagation mechanism can significantly enhance the thermal shock resistance of the material. The flux improves the density of the green body by reducing the sintering temperature and promoting liquid-phase sintering, forms a low-expansion phase, and reduces the difference in thermal expansion coefficient. Kaolin, as a traditional ceramic raw material, dehydrates to form mullite crystal phase at high temperature, providing high strength and chemical stability, and ensuring the framework structure of the matrix layer. The design of the intermediate transition layer is to alleviate the thermal stress problem caused by the difference in thermal expansion coefficient between the matrix layer and the surface dense layer. The selection of anorthite and β-tricalcium phosphate, as well as the addition of pore-forming agents, helps to provide the necessary elasticity to adapt to volume changes caused by temperature changes while ensuring a certain mechanical strength. The introduction of anorthite reduces the concentration of thermal stress and enhances the thermal shock resistance of the material, while the low sintering activity and high chemical stability of β-tricalcium phosphate further reduce the interlayer thermal expansion difference. The pore-forming agent decomposes to generate gas during sintering, forming a microporous structure. These micropores serve as stress release channels, inhibiting crack propagation and ensuring the overall uniformity and thermal shock resistance of the material. The surface dense layer is mainly composed of ZrO2 and SiO2. Nano-ZrO2 has a high melting point and low thermal conductivity, and its transformation toughening significantly improves the crack propagation resistance of the surface layer. Nano-SiO2 forms a composite oxide with ZrO2, forming a highly dense and low-porosity surface layer, reducing stress concentration caused by thermal expansion differences. By precisely controlling the sintering process and laser surface treatment parameters, the microstructure of the surface layer can be further optimized to make it have a higher density and better wear resistance. Research shows that this multi-layer structure design can significantly improve the thermal shock resistance of the material by effectively dispersing and absorbing heat and reducing thermal stress concentration points.

[0023] The preparation of modified palygorskite optimizes its dispersibility and interfacial bonding strength through acid activation and magnesium ion modification. Palygorskite is first activated with hydrochloric acid solution to remove surface impurities and expose active hydroxyl groups, and then combined with Mg 2+ under alkaline conditions to form a magnesium aluminosilicate layer, enhancing its chemical bonding with the ceramic matrix. Literature shows that this bridging effect or interface blocking crack propagation mechanism can significantly enhance the thermal shock resistance of the material. And by replacing Ca 2+ in the interlayer with Mg 2+ with a smaller ionic radius to replace Ca 2+After that, the interlayer structure of palygorskite becomes more stable, reducing its coefficient of thermal expansion. In addition, in an alkaline environment, Mg 2+ backfills the octahedral sites, not only repairing the structural defects caused by acid etching, but also introducing stable magnesium-silicon oxygen bonds to inhibit crack initiation at high temperatures, further enhancing the thermal stability of the material.

[0024] Electrostatic spraying and spin coating techniques ensure the uniform deposition of the intermediate layer and the surface layer and the bonding between layers, avoiding the delamination problem of traditional spraying. Electrostatic spraying can precisely control the thickness of the intermediate transition layer, and the pore distribution is uniform, optimizing the thermal expansion transition. The segmented sintering strategy avoids the accumulation of residual stress during the sintering process. The low-temperature section promotes the melting of the flux to complete the liquid-phase sintering network; the high-temperature section completes the formation of the main crystal phase, and at the same time, the ZrO2 / SiO2 layer densifies at high temperatures. Slow heating reduces thermal stress and ensures uniform shrinkage of the multi-layer structure. Laser surface treatment further refines the grains and forms a dense amorphous layer through local melting and rapid cooling, reducing the coefficient of thermal expansion of the surface layer while improving hardness and wear resistance. Detailed implementation mode

[0025] The technical solutions and their effects of the present invention are further described below through specific examples. The following examples are only used to illustrate the content of the present invention and do not limit the protection scope of the present invention. Simple changes made to the present invention using the concept of the present invention are within the scope of protection required by the present invention.

[0026] The equipment used in the preparation method of the present invention can all adopt well-known equipment in the art. The raw materials used in the present invention are all commercially available unless otherwise specified.

[0027] Example 1

[0028] S1. The palygorskite is centrifugally classified to obtain palygorskite powder with a particle size <1 μm. Take 10 g of the powder and place it in a 2 L beaker. Add 1800 mL of 4.5 mol / L HCl solution, and the magnetic stirring speed is 500 rpm. Keep it in a constant temperature water bath at 60 °C for 3 hours, then quickly cool it to 20 °C in an ice bath, centrifuge at a speed of 8000 rpm for 10 min, take the lower precipitate, wash it with deionized water, and dry it in a vacuum at 60 °C for 12 hours to obtain acid-activated palygorskite. Take 800 ppm MgCl2 solution and adjust it to pH 8.5 with 0.1 M NaOH. Transfer the acid-activated palygorskite to a reaction kettle, with a temperature of 100 °C and a pressure of 0.15 MPa, react for 36 hours, cool it, centrifuge it, wash it with deionized water, and dry it at 80 °C to obtain modified palygorskite.

[0029] S2. Mix 30 wt% hydroxyapatite, 20 wt% bone ash, 6 wt% modified palygorskite, 12 wt% flux, and 32 wt% kaolin, then add water and wet ball mill for 4 hours with a material-ball-water ratio of 1:3:1. The flux is a mixture of Li2CO3 and MgO with a mass ratio of 2:1. Then, inject the slurry into a gypsum mold at a pressure of 0.3 MPa, keep the pressure for 30 minutes, with the wet blank thickness of 6 mm, and dry at room temperature for 48 hours to obtain the matrix layer. Mix 60 wt% anorthite, 39 wt% β-tricalcium phosphate, and 1 wt% ammonium carbonate pore former, and perform electrostatic spraying on the matrix layer with an electrostatic spraying voltage of 40 kV, a spray gun distance of 15 cm, and a deposition rate of 0.18 g / s to form a 0.4 mm intermediate transition layer. Disperse 30 wt% nano-ZrO2 and 70 wt% nano-SiO2 in ethylene glycol monomethyl ether to obtain a mixture with a solid content of 20%, ultrasonically treat for 30 minutes, and spin coat the mixture on the intermediate transition layer at a spin coating speed of 2000 rpm for 30 seconds, and perform secondary spin coating after an interval of 5 minutes to form a surface dense layer, and cure at room temperature to obtain an unsintered green body.

[0030] S3. Segmentally sinter the green body obtained in S2. Under a nitrogen atmosphere with a flow rate of 5 L / min, heat it to 750 °C at a rate of 3 °C / min, hold for 20 minutes, then heat it to 1100 °C at a rate of 0.5 °C / min, hold for 20 minutes, and then cool to room temperature.

[0031] S4. Perform laser surface treatment on the surface dense layer for laser surface densification. The laser wavelength is 1064 nm, the pulse width is 10 ns, the power is 500 W, the spot diameter is 0.3 mm, perform one-way parallel line scanning with a spacing of 0.2 mm and a speed of 4 mm / s.

[0032] Example 2

[0033] S1. Obtain palygorskite powder with a particle size <1 μm by centrifugal classification of palygorskite. Take 10 g of the powder and place it in a 2 L beaker, add 2000 mL of 5.0 moI / L HCI solution, stir magnetically at a speed of 500 rpm, keep it in a constant temperature water bath at 75 °C, react for 5.5 hours, then quickly cool to 20 °C in an ice bath, centrifuge at a speed of 8000 rpm for 10 min, take the lower layer precipitate and wash it with deionized water, and dry it in a vacuum at 60 °C for 12 hours to obtain acid-activated palygorskite. Take 1000 ppm MgCl2 solution and adjust its pH to 9.0 with 0.1 M NaOH, transfer the acid-activated palygorskite to a reaction kettle, with a temperature of 110 °C and a pressure of 0.18 MPa, react for 48 hours, cool and then centrifuge, wash with deionized water, and dry at 80 °C to obtain modified palygorskite.

[0034] S2. Mix 25 wt% hydroxyapatite, 30 wt% bone ash, 5.5 wt% modified palygorskite, 10.5 wt% flux, and 29 wt% kaolin, then add water and perform wet ball milling for 4 hours with a material-ball-water ratio of 1:3:1. The flux is a mixture of Li2CO3 and MgO with a mass ratio of 3:1. Then, inject the slurry into a gypsum mold at a pressure of 0.5 MPa, keep the pressure for 30 minutes, with the wet blank thickness of 8 mm, and dry at room temperature for 48 hours to obtain the matrix layer; mix 55 wt% anorthite, 44.4 wt% β-tricalcium phosphate, and 0.6 wt% ammonium carbonate pore former, and perform electrostatic spraying on the matrix layer with an electrostatic spraying voltage of 50 kV, a spray gun distance of 15 cm, and a deposition rate of 0.18 g / s to form a 0.5 mm intermediate transition layer; disperse 35 wt% nano-ZrO2 and 65 wt% nano-SiO2 in ethylene glycol monomethyl ether to obtain a mixture with a solid content of 25%, perform ultrasonic treatment for 30 minutes, and spin-coat the mixture on the intermediate transition layer at a spin-coating speed of 2000 rpm for 30 seconds, and perform secondary spin-coating after an interval of 5 minutes to form a surface dense layer, and cure at room temperature to obtain the unsintered green body.

[0035] S3. Segmentally sinter the green body obtained in S2. Under a nitrogen atmosphere with a flow rate of 5 L / min, heat it to 800 °C at a rate of 5 °C / min, hold for 30 minutes, then heat it to 1150 °C at a rate of 1 °C / min, hold for 30 minutes, and then cool to room temperature.

[0036] S4. Perform laser surface treatment on the surface dense layer for laser surface densification. The laser wavelength is 1064 nm, the pulse width is 10 ns, the power is 600 W, the spot diameter is 0.5 mm, perform unidirectional parallel line scanning with a spacing of 0.2 mm and a speed of 3.5 mm / s.

[0037] Example 3

[0038] S1. Obtain palygorskite powder with a particle size <1 μm by centrifugal classification of palygorskite. Take 10 g of the powder and place it in a 2 L beaker, add 2200 mL of 5.5 mol / L HCI solution, stir magnetically at a speed of 500 rpm, keep the water bath at 90 °C, react for 8 hours, then quickly cool to 20 °C in an ice bath, centrifuge at a speed of 8000 rpm for 10 min, take the lower precipitate, wash it with deionized water, and dry it in a vacuum at 60 °C for 12 hours to obtain acid-activated palygorskite. Take 1200 ppm MgCl2 solution and adjust its pH to 9.5 with 0.1 M NaOH, transfer the acid-activated palygorskite to a reaction kettle, with a temperature of 120 °C and a pressure of 0.20 MPa, react for 60 hours, cool and then centrifuge, wash with deionized water, and dry at 80 °C to obtain modified palygorskite.

[0039] S2. Mix 45 wt% hydroxyapatite, 20 wt% bone ash, 3 wt% modified palygorskite, 6 wt% flux, and 26 wt% kaolin, then add water and wet ball mill for 4 hours with a material:ball:water ratio of 1:3:1. The flux is a mixture of Li2CO3 and MgO with a mass ratio of 4:1. Then, inject the slurry into a gypsum mold at a pressure of 0.7 MPa, keep the pressure for 30 minutes, with the wet embryo thickness of 10 mm, and dry at room temperature for 48 hours to obtain the matrix layer. Mix 58 wt% anorthite, 40 wt% β-tricalcium phosphate, and 2 wt% ammonium carbonate pore former, and perform electrostatic spraying on the matrix layer with an electrostatic spraying voltage of 60 kV, a spray gun distance of 15 cm, and a deposition rate of 0.18 g / s to form a 0.6 mm intermediate transition layer. Disperse 40 wt% nano-ZrO2 and 60 wt% nano-SiO2 in ethylene glycol monomethyl ether to obtain a mixture with a solid content of 30%, ultrasonically treat for 30 minutes, and spin coat the mixture on the intermediate transition layer at a spin coating speed of 2000 rpm for 30 seconds, and perform secondary spin coating after an interval of 5 minutes to form a surface dense layer, and cure at room temperature to obtain the unsintered embryo.

[0040] S3. Segmentally sinter the embryo obtained in S2. Under an ammonia atmosphere with a flow rate of 5 L / min, heat it at a rate of 8 °C / min to 850 °C, hold for 40 minutes, then heat it at a rate of 2 °C / min to 1200 °C, hold for 40 minutes, and then cool to room temperature.

[0041] S4. Perform laser surface treatment on the surface dense layer for laser surface densification. The laser wavelength is 1064 nm, the pulse width is 10 ns, the power is 700 W, the spot diameter is 0.7 mm, perform one-way parallel line scanning with a spacing of 0.2 mm and a speed of 5 mm / s.

[0042] Comparative Example 1

[0043] S1. Mix 30 wt% hydroxyapatite, 20 wt% bone ash, 6 wt% palygorskite, 12 wt% flux, and 32 wt% kaolin, then add water and wet ball mill for 4 hours with a material-to-ball-to-water ratio of 1:3:1. The flux is a mixture of Li2CO3 and MgO with a mass ratio of 2:1. Then, inject the slurry into a gypsum mold at a pressure of 0.3 MPa, keep the pressure for 30 minutes, with the wet blank thickness of 6 mm, and dry at room temperature for 48 hours to obtain the matrix layer. Mix 60 wt% anorthite, 39 wt% β-tricalcium phosphate, and 1 wt% ammonium carbonate pore former, and perform electrostatic spraying on the matrix layer with an electrostatic spraying voltage of 40 kV, a spray gun distance of 15 cm, and a deposition rate of 0.18 g / s to form a 0.4-mm intermediate transition layer. Disperse 30 wt% nano-ZrO2 and 70 wt% nano-SiO2 in ethylene glycol monomethyl ether to obtain a mixture with a solid content of 20%. Ultrasonically treat for 30 minutes, and spin-coat the mixture on the intermediate transition layer at a spin-coating speed of 2000 rpm for 30 seconds. After a 5-minute interval, perform secondary spin-coating to form a surface dense layer, and cure at room temperature to obtain the unsintered green body.

[0044] S3. Segmentally sinter the green body obtained in S2. Under a nitrogen atmosphere with a flow rate of 5 L / min, heat it at a rate of 3 °C / min to 750 °C, hold for 20 minutes, then heat it at a rate of 0.5 °C / min to 1100 °C, hold for 20 minutes, and then cool to room temperature.

[0045] S4. Perform laser surface treatment on the surface dense layer for laser surface densification. The laser wavelength is 1064 nm, the pulse width is 10 ns, the power is 500 W, the spot diameter is 0.3 mm, perform one-way parallel line scanning with a spacing of 0.2 mm and a speed of 4 mm / s.

[0046] Comparative Example 2

[0047] S1. Centrifugally classify palygorskite to obtain palygorskite powder with a particle size <1 μm. Take 10 g of the powder and place it in a 2-L beaker, add 1800 mL of 4.5 mol / L HCl solution, stir magnetically at a speed of 500 rpm, keep it in a constant-temperature water bath at 60 °C for 3 hours, then quickly cool it to 20 °C in an ice bath, centrifuge at a speed of 8000 rpm for 10 min, take the lower precipitate, wash it with deionized water, and vacuum dry it at 60 °C for 12 hours to obtain acid-activated palygorskite. Take 800 ppm MgCl2 solution and adjust its pH to 8.5 with 0.1 M NaOH. Transfer the acid-activated palygorskite to a reaction kettle at a temperature of 100 °C and a pressure of 0.15 MPa, react for 36 hours, cool and then centrifuge, wash with deionized water, and dry at 80 °C to obtain modified palygorskite.

[0048] S2. Mix 30 wt% hydroxyapatite, 20 wt% bone ash, 6 wt% modified palygorskite, 12 wt% flux, and 32 wt% kaolin, then add water and perform wet ball milling for 4 hours with a material-ball-water ratio of 1:3:1. The flux is a mixture of Li2CO3 and MgO with a mass ratio of 2:1. Then, inject the slurry into a gypsum mold at a pressure of 0.3 MPa, keep the pressure for 30 minutes, with the wet blank thickness of 6 mm, and dry at room temperature for 48 hours to obtain the matrix layer. Disperse 30 wt% nano-ZrO2 and 70 wt% nano-SiO2 in ethylene glycol monomethyl ether to obtain a mixture with a solid content of 20%. Ultrasonically treat it for 30 minutes, and spin-coat the mixture onto the matrix layer by the spin-coating process at a spin-coating speed of 2000 rpm for 30 seconds. After a 5-minute interval, perform secondary spin-coating to form a surface dense layer, and cure at room temperature to obtain the unsintered green body.

[0049] S3. Segmentally sinter the green body obtained in S2. Under a nitrogen atmosphere with a flow rate of 5 L / min, heat it at a rate of 3 °C / min to 750 °C, hold for 20 minutes, then heat it at a rate of 0.5 °C / min to 1100 °C, hold for 20 minutes, and then cool to room temperature.

[0050] S4. Perform laser surface treatment on the surface dense layer for laser surface densification. The laser wavelength is 1064 nm, the pulse width is 10 ns, the power is 500 W, the spot diameter is 0.3 mm, perform one-way parallel line scanning with a spacing of 0.2 mm and a speed of 4 mm / s.

[0051] Comparative Example 3

[0052] S1. Obtain palygorskite powder with a particle size <1 μm by centrifugal classification of palygorskite. Take 10 g of the powder and place it in a 2 L beaker, add 1800 mL of 4.5 mol / L HCl solution, with a magnetic stirring speed of 500 rpm, and keep it in a constant temperature water bath at 60 °C. After reacting for 3 hours, quickly cool it to 20 °C in an ice bath, centrifuge at a speed of 8000 rpm for 10 min, take the lower precipitate, wash it with deionized water, and vacuum dry it at 60 °C for 12 hours to obtain acid-activated palygorskite. Take 800 ppm MgCl2 solution and adjust its pH to 8.5 with 0.1 M NaOH. Transfer the acid-activated palygorskite to a reaction kettle, with a temperature of 100 °C and a pressure of 0.15 MPa, react for 36 hours, cool it, centrifuge it, wash it with deionized water, and dry it at 80 °C to obtain modified palygorskite.

[0053] S2. Mix 30 wt% hydroxyapatite, 20 wt% bone ash, 6 wt% modified palygorskite, 12 wt% flux, and 32 wt% kaolin, then add water and wet ball mill for 4 hours with a material:ball:water ratio of 1:3:1. The flux is a mixture of Li2CO3 and MgO with a mass ratio of 2:1. Then, inject the slurry into a gypsum mold at a pressure of 0.3 MPa, keep the pressure for 30 minutes, with the wet blank thickness of 6 mm, and dry at room temperature for 48 hours to obtain the matrix layer. Mix 60 wt% anorthite, 39 wt% β-tricalcium phosphate, and 1 wt% ammonium carbonate pore-forming agent, and perform electrostatic spraying on the matrix layer with an electrostatic spraying voltage of 40 kV, a spray gun distance of 15 cm, and a deposition rate of 0.18 g / s to form a 0.4-mm intermediate transition layer, thus obtaining the unsintered green body.

[0054] S3. Subject the green body obtained in S2 to segmented sintering. Under a nitrogen atmosphere with a flow rate of 5 L / min, heat it at a rate of 3 °C / min to 750 °C, hold for 20 minutes, then heat it at a rate of 0.5 °C / min to 1100 °C, hold for 20 minutes, and then cool it to room temperature.

[0055] Comparative Example 4

[0056] S1. Obtain palygorskite powder with a particle size <1 μm by centrifugal classification of palygorskite. Take 10 g of the powder and place it in a 2-L beaker, add 1800 mL of 4.5 mol / L HCl solution, stir magnetically at a speed of 500 rpm, keep it in a constant temperature water bath at 60 °C, after reacting for 3 hours, quickly cool it to 20 °C in an ice bath, centrifuge at a speed of 8000 rpm for 10 min, take the lower precipitate, wash it with deionized water, and dry it in a vacuum at 60 °C for 12 hours to obtain acid-activated palygorskite. Take 800 ppm MgCl2 solution and adjust its pH to 8.5 with 0.1 M NaOH, transfer the acid-activated palygorskite to a reaction kettle, with a temperature of 100 °C and a pressure of 0.15 MPa, react for 36 hours, cool it and then centrifuge, wash it with deionized water, and dry it at 80 °C to obtain modified palygorskite.

[0057] S2. Mix 30 wt% hydroxyapatite, 20 wt% bone ash, 6 wt% modified palygorskite, 12 wt% flux, and 32 wt% kaolin, then add water and wet ball mill for 4 hours with a material-ball-water ratio of 1:3:1. The flux is a mixture of Li2CO3 and MgO with a mass ratio of 2:1. Then, inject the slurry into a gypsum mold at a pressure of 0.3 MPa, keep the pressure for 30 minutes, with the wet blank thickness of 6 mm, and dry at room temperature for 48 hours to obtain the matrix layer. Mix 60 wt% anorthite, 39 wt% β-tricalcium phosphate, and 1 wt% ammonium carbonate pore former, and perform electrostatic spraying on the matrix layer with an electrostatic spraying voltage of 40 kV, a spray gun distance of 15 cm, and a deposition rate of 0.18 g / s to form a 0.4-mm intermediate transition layer. Disperse 30 wt% nano-ZrO2 and 70 wt% nano-SiO2 in ethylene glycol monomethyl ether to obtain a mixture with a solid content of 20%, ultrasonically treat for 30 minutes, and spin coat the mixture on the intermediate transition layer at a spin coating speed of 2000 rpm for 30 seconds, and perform secondary spin coating after an interval of 5 minutes to form a surface dense layer, and cure at room temperature to obtain the unsintered blank.

[0058] S3. Segmentally sinter the blank obtained in S2. Under a nitrogen atmosphere with a flow rate of 5 L / min, heat it up to 750 °C at a rate of 3 °C / min, hold for 20 minutes, then heat it up to 1100 °C at a rate of 0.5 °C / min, hold for 20 minutes, and then cool to room temperature.

[0059] Test the specimens of the examples and comparative examples. The specimens are circular discs with a diameter of 50 ± 1 mm. Heat them up to the initial temperature of 200 °C in an electrothermal blast drying oven at a heating rate of 5 °C / min, hold for 30 minutes, then quickly transfer them to deionized water at 25 ± 1 °C and soak for 10 minutes, and record the maximum temperature difference that the specimens can withstand without cracks or damage. For the thermal cycle test, keep the specimens in an electrothermal blast drying oven at 200 °C for 30 min, quickly transfer them to deionized water at 20 ± 1 °C and soak for 10 minutes, repeat until cracks occur, and record the number of cycles. The test results are shown in Table 1.

[0060] Table 1: Detection of thermal shock resistance of specimens.

[0061]

[0062] For mechanical testing, test the three-point bending strength according to GB / T 4741-1999 and the fracture toughness according to GB / T 23806-2009. The specimen size is 3 mm × 4 mm, the span is 30 mm, and the loading rate is: 0.5 mm / min for bending strength and 0.05 mm / min for fracture toughness. The test results are shown in Table 2.

[0063] Table 2: Detection of mechanical properties of specimens.

[0064]

Claims

1. A high thermal shock resistance bone china, characterized in that: It sequentially includes a matrix layer, an intermediate transition layer and a surface dense layer; The matrix layer includes the following substances in weight percentages: 25 - 45% hydroxyapatite, 20 - 30% bone ash, 3 - 8% modified palygorskite, 6 - 15% flux and 20 - 35% kaolin; The intermediate transition layer includes the following substances in weight percentages: 55 - 60% anorthite, 35 - 45% β-tricalcium phosphate and 0.6 - 2% pore former, and the sum of the weight percentages of the above components is 100%; The surface dense layer includes the following substances in weight percentages: 30 - 40% ZrO2, 60 - 70% SiO2; The modification method of the modified palygorskite is as follows: Mix palygorskite with hydrochloric acid solution, react at 60 - 90 °C for 3 - 8 hours, after centrifugal washing, place it in an Mg 2+ solution, react at 100 - 120 °C for 36 - 60 hours, and obtain the modified palygorskite after drying.

2. The high thermal shock resistance bone china according to claim 1, characterized in that: The flux is one or both of lithium carbonate and magnesium oxide, and the pore former is ammonium carbonate.

3. The preparation method of the high thermal shock resistance bone china according to any one of claims 1 - 2, characterized in that: S1. Mix palygorskite with hydrochloric acid solution, react at 60 - 90 °C for 3 - 8 hours, centrifuge and wash, then place in an Mg solution of 800 - 1200 ppm, react at 100 - 120 °C for 36 - 60 hours, and obtain modified palygorskite after drying; 2+ ​ S2. Mix hydroxyapatite, bone ash, the modified palygorskite obtained in S1, flux and kaolin, then ball mill them, carry out slip casting to obtain a wet blank of the matrix layer, and then deposit the intermediate transition layer on the surface of the matrix layer by electrostatic spraying of anorthite, β-tricalcium phosphate and pore former, and finally spin coat a suspension of nano ZrO2 and SiO2 to obtain the surface dense layer; S3. Carry out segmented sintering on the blank obtained in S2, heat it up to 750 - 850°C at a rate of 3 - 8°C / min in a nitrogen atmosphere, hold for 20 - 40 min; heat it up to 1100 - 1200°C at a rate of 0.5 - 2°C / min, hold for 20 - 40 min, and then cool to room temperature; S4. Carry out laser surface treatment on the surface dense layer, with a power of 500 - 700 W, a scanning speed of 2 - 5 mm / s, and a spot diameter of 0.3 - 0.7 mm.

4. The preparation method of the high thermal shock resistance bone china according to claim 3, characterized in that: The particle size of the palygorskite in step S1 is <1 μm, the concentration of the hydrochloric acid solution is 4.5 - 5.5 mol / L, and the palygorskite and the hydrochloric acid solution are mixed at a solid-liquid mass ratio of 1:180 - 220.

5. The preparation method of the high thermal shock resistance bone china according to claim 3, characterized in that: The Mg described in step S1 2+ solution is adjusted to a pH of 8.5 - 9.5 with sodium hydroxide solution.

6. The preparation method of the high thermal shock resistance bone china according to claim 3, characterized in that: The hydroxyapatite, bone ash, the modified palygorskite obtained in S1, flux and kaolin in step S2 are ball milled to D50 of 1.5 - 2.5 μm.

7. The preparation method of the high thermal shock resistance bone china according to claim 3, characterized in that: The slip casting pressure in step S2 is 0.3 - 0.7 MPa, and the thickness of the wet blank is 6 - 10 mm.

8. The preparation method of the high thermal shock resistance bone china according to claim 3, characterized in that: The electrostatic spraying voltage in step S2 is 40 - 60 kV, and the thickness of the intermediate transition layer is 0.4 - 0.6 mm.

9. The preparation method of the high thermal shock resistance bone china according to claim 3, characterized in that: For the laser surface treatment described in step S4, the laser wavelength is 1064 nm, the pulse width is 10 ns, the power is 500 - 800 W, the spot diameter is 0.3 - 0.7 mm, and the scanning speed is 2 - 5 mm / s.

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