Environment-friendly ceramic and preparation method thereof

Abstract

The application discloses an environment-friendly ceramic and a preparation method thereof, and belongs to the technical field of ceramics. The environment-friendly ceramic comprises the following raw materials in parts by weight: 30-50 parts of red mud, 20-40 parts of fly ash, 10-25 parts of purple sand soil, 5-15 parts of quartz, 3-8 parts of a composite binder, 3-8 parts of a composite fluxing agent, and 40-50 parts of deionized water. The environment-friendly ceramic prepared by the method has excellent bending strength and apparent porosity.

Description

Technical Field

[0001] This invention relates to the field of ceramic technology, specifically to an environmentally friendly ceramic and its preparation method. Background Technology

[0002] In traditional ceramic manufacturing processes, the mechanical properties of the green body (such as flexural strength) are key initial factors affecting the final properties of sintered ceramic products. As the initial form of ceramics before sintering, the bonding state between internal particles, pore structure, and overall uniformity of the green body directly determine the mechanical properties of the product during subsequent sintering.

[0003] However, the widely used organic binders still have some shortcomings in ceramic green body forming. On the one hand, the bonding force between the binder and ceramic particles is relatively weak, resulting in low initial strength of the green body. This makes it prone to breakage or microcrack propagation during handling, processing, or pre-sintering pretreatment, leading to a decrease in yield. On the other hand, organic binders decompose and volatilize during the removal stage before high-temperature sintering, leaving behind numerous pores. Excessive or unevenly distributed pores can hinder mass transport during sintering and inhibit uniform grain boundary migration. This not only leads to insufficient densification but may also cause abnormal grain growth, ultimately resulting in an inhomogeneous microstructure. Consequently, ceramic products exhibit problems such as high brittleness and poor reliability in practical applications. Therefore, developing an environmentally friendly ceramic with excellent flexural strength and low apparent porosity has become a critical issue that urgently needs to be addressed in the ceramics field. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the purpose of this invention is to provide an environmentally friendly ceramic and its preparation method.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] An environmentally friendly ceramic comprising the following raw materials in parts by weight:

[0007] Red mud 30-50 parts, fly ash 20-40 parts, purple clay 10-25 parts, quartz 5-15 parts, composite binder 3-8 parts, composite flux 3-8 parts, deionized water 40-50 parts;

[0008] The composite adhesive is prepared by the following method:

[0009] S1: Hydroxyapatite reacts with 3-aminopropyltriethoxysilane to produce silane-modified hydroxyapatite.

[0010] S2: Silane-modified hydroxyapatite reacts with oxidized chitosan under the action of a catalyst to generate chitosan-modified silane hydroxyapatite.

[0011] S3: Chitosan-modified silane hydroxyapatite reacts with mercapto-based polyethylene glycol amino groups under the action of a catalyst to generate polyethylene glycol-modified hydroxyapatite.

[0012] S4: Polyethylene glycol-modified hydroxyapatite reacts with borax pentahydrate to form a composite binder.

[0013] In step S1, the mass ratio of hydroxyapatite to 3-aminopropyltriethoxysilane is 100:(1-3).

[0014] In step S2, the mass ratio of silane-modified hydroxyapatite to oxidized chitosan is 10:(1-3).

[0015] In step S3, the mass ratio of chitosan-modified silane hydroxyapatite to mercapto-polyethylene glycol amino is 10:(1-2.5).

[0016] In step S4, the mass ratio of polyethylene glycol-modified hydroxyapatite to borax pentahydrate is 100:(2-3).

[0017] The composite flux is a mixture of spodumene and waste glass powder.

[0018] The weight ratio of spodumene to waste glass powder is 1:(1.5-2.5).

[0019] In step S2, the catalyst is glacial acetic acid.

[0020] In step S3, the catalyst is glacial acetic acid.

[0021] A method for preparing environmentally friendly ceramics includes the following steps:

[0022] (1) Weigh out the following by weight: 30-50 parts red mud, 20-40 parts fly ash, 10-25 parts purple clay, 5-15 parts quartz, 3-8 parts composite binder, 3-8 parts composite flux, and 40-50 parts deionized water.

[0023] (2) Dry the red mud and fly ash, and then pass them through a 100-mesh sieve; put the red mud, fly ash, purple clay, quartz, composite binder and composite flux into a ball mill, add deionized water, ball mill, and pass through a 200-mesh sieve to obtain a uniform slurry;

[0024] (3) Spray granulation of the slurry to obtain granular powder; after aging the powder in a closed environment for 24-48 hours, place it in a mold and press it to form a green body; place the green body in a sintering furnace, raise the temperature from room temperature to 450-500℃ and hold it for 30-40 minutes; then raise the temperature to 1080℃-1150℃ and hold it for 30-60 minutes; finally cool it to room temperature to obtain environmentally friendly ceramics.

[0025] Due to the adoption of the above technical solutions, the beneficial effects of the present invention include:

[0026] The environmentally friendly ceramics prepared by this invention have excellent flexural strength and apparent porosity. Detailed Implementation

[0027] The following description, in conjunction with specific embodiments, provides further details, but the present invention is not limited to these embodiments.

[0028] Example 1: Preparation of composite adhesive:

[0029] S1: Weigh 1g of 3-aminopropyltriethoxysilane, add 20ml of deionized water, and stir at 40℃ for 3h to obtain 3-aminopropylsilanetriol; add 100g of hydroxyapatite to 500ml of 50wt% ethanol aqueous solution, and ultrasonically disperse for 15min to obtain hydroxyapatite dispersion; under nitrogen protection, slowly add 3-aminopropylsilanetriol dropwise to the hydroxyapatite dispersion over 20min. After the addition is complete, raise the temperature to 90℃ and react for 8h. Then cool to room temperature, filter, wash three times with deionized water (200ml of deionized water each time), vacuum dry at 60℃ for 10h, grind and pulverize, and pass through an 80-mesh sieve to obtain silane-modified hydroxyapatite; the reaction equation is shown below:

[0030]

[0031] in, This is a schematic diagram of hydroxyapatite. The surface of hydroxyapatite is rich in hydroxyl groups. The active hydroxyl groups (-OH) on the surface are condensed with silanols after hydrolysis of silane coupling agents to form Si-OP covalent bonds.

[0032] S2: Under nitrogen protection, 500 ml of anhydrous ethanol, 100 g of silane-modified hydroxyapatite, and 5 ml of glacial acetic acid were added to the reactor. The temperature was raised to 35°C and stirred for 20 min. Then, 100 ml of a 1 wt% acetic acid aqueous solution containing 10 g of oxidized chitosan was slowly added dropwise over 20 min. After the addition was complete, the temperature was raised to 60°C and reacted for 10 h. The temperature was then lowered to room temperature, and the pH was adjusted to neutral with 5 wt% NaOH solution. The reaction solution was poured into 800 ml of acetone, stirred, and the precipitate was collected. The precipitate was filtered, washed three times with acetone (300 ml of acetone each time), and dried under vacuum at 45°C for 12 h to obtain chitosan-modified silane hydroxyapatite. The reaction equation is shown below:

[0033]

[0034] S3: Under nitrogen protection, 500 ml of anhydrous ethanol, 100 g of chitosan-modified silane hydroxyapatite, and 5 ml of glacial acetic acid were added to the reactor. The mixture was heated to 35°C and stirred for 20 min. Then, 100 ml of a deionized aqueous solution containing 10 g of mercapto-polyethylene glycol amino (SH-PEG-NH2, number average molecular weight 1000) was slowly added dropwise over 20 min. After the addition was complete, the mixture was heated to 60°C and reacted for 10 h. The temperature was then lowered to room temperature, and the pH was adjusted to neutral with 5 wt% NaOH solution. The reaction solution was poured into 800 ml of acetone, stirred to precipitate, filtered, and washed three times with acetone (300 ml of acetone each time). The precipitate was then dried under vacuum at 50°C for 12 h to obtain polyethylene glycol-modified hydroxyapatite. The reaction equation is shown below.

[0035]

[0036] S4: Add 500ml of phosphate buffer (0.1M, pH=8.5) and 100g of polyethylene glycol modified hydroxyapatite to the reactor and stir for 2h. Dissolve 2g of borax pentahydrate in 20mL of 50℃ deionized water and stir until completely dissolved. Slowly add the solution dropwise to the reactor over 20min. After the addition is complete, raise the temperature to 50℃ and react for 5h. Add 0.5M HCl to adjust the pH to 7.0. Then add 20ml of glycerol and 80ml of deionized water and stir to mix well to obtain the composite binder.

[0037] Example 2: Preparation of composite adhesive:

[0038] S1: Weigh 2g of 3-aminopropyltriethoxysilane, add 20ml of deionized water, and stir at 40℃ for 3h to obtain 3-aminopropylsilanetriol; add 100g of hydroxyapatite to 500ml of 50wt% ethanol aqueous solution, and sonicate for 15min to obtain hydroxyapatite dispersion; under nitrogen protection, slowly add 3-aminopropylsilanetriol dropwise to hydroxyapatite dispersion over 20min, after which the temperature is raised to 90℃, react for 8h, cool to room temperature, filter, wash 3 times with deionized water (200ml of deionized water each time), vacuum dry at 60℃ for 10h, grind and pulverize, and pass through an 80-mesh sieve to obtain silane-modified hydroxyapatite;

[0039] S2: Under nitrogen protection, 500 ml of anhydrous ethanol, 100 g of silane-modified hydroxyapatite, and 5 ml of glacial acetic acid were added to the reactor. The temperature was raised to 35°C and stirred for 20 min. 100 ml of 1 wt% acetic acid aqueous solution containing 20 g of oxidized chitosan was slowly added dropwise over 20 min. After the addition was complete, the temperature was raised to 65°C and reacted for 9 h. The temperature was then lowered to room temperature, and the pH was adjusted to neutral with 5 wt% NaOH solution. The reaction solution was poured into 800 ml of acetone, stirred to precipitate, filtered, and washed three times with acetone (300 ml of acetone each time). The mixture was then vacuum dried at 45°C for 12 h to obtain chitosan-modified silane hydroxyapatite.

[0040] S3: Under nitrogen protection, add 500 ml of anhydrous ethanol, 100 g of chitosan-modified silane hydroxyapatite, and 5 ml of glacial acetic acid to the reactor. Heat to 35°C and stir for 20 min. Slowly add 100 ml of deionized water containing 18 g of mercaptopolyethylene glycol amino (SH-PEG-NH2, number average molecular weight of 1000) dropwise over 20 min. After the addition is complete, heat to 65°C and react for 9 h. Then cool to room temperature and adjust the pH to neutral with 5 wt% NaOH solution. Pour the reaction solution into 800 ml of acetone, stir to precipitate, filter, wash three times with acetone (300 ml of acetone each time), and vacuum dry at 50°C for 12 h to obtain polyethylene glycol-modified hydroxyapatite.

[0041] S4: Add 500ml of phosphate buffer (0.1M, pH=8.5) and 100g of polyethylene glycol modified hydroxyapatite to the reactor and stir for 2h. Dissolve 2g of borax pentahydrate in 20mL of 50℃ deionized water and stir until completely dissolved. Slowly add the solution dropwise to the reactor over 20min. After the addition is complete, raise the temperature to 55℃ and react for 4h. Add 0.5M HCl to adjust the pH to 7.0. Then add 20ml of glycerol and 80ml of deionized water and stir to mix well to obtain the composite binder.

[0042] Example 3: Preparation of composite adhesive:

[0043] S1: Weigh 3g of 3-aminopropyltriethoxysilane, add 20ml of deionized water, and stir at 40℃ for 3h to obtain 3-aminopropylsilanetriol; add 100g of hydroxyapatite to 500ml of 50wt% ethanol aqueous solution, and ultrasonically disperse for 15min to obtain hydroxyapatite dispersion; under nitrogen protection, slowly add 3-aminopropylsilanetriol dropwise to the hydroxyapatite dispersion over 20min, and after the addition is complete, heat to 90℃, react for 8h, cool to room temperature, filter, wash 3 times with deionized water (200ml of deionized water each time), vacuum dry at 60℃ for 10h, grind and pulverize, and pass through an 80-mesh sieve to obtain silane-modified hydroxyapatite;

[0044] S2: Under nitrogen protection, 500 ml of anhydrous ethanol, 100 g of silane-modified hydroxyapatite, and 5 ml of glacial acetic acid were added to the reactor. The temperature was raised to 35°C and stirred for 20 min. 100 ml of 1 wt% acetic acid aqueous solution containing 30 g of oxidized chitosan was slowly added dropwise over 20 min. After the addition was complete, the temperature was raised to 70°C and reacted for 8 h. The temperature was then lowered to room temperature, and the pH was adjusted to neutral with 5 wt% NaOH solution. The reaction solution was poured into 800 ml of acetone, stirred to precipitate, filtered, and washed three times with acetone (300 ml of acetone each time). The mixture was then vacuum dried at 45°C for 12 h to obtain chitosan-modified silane hydroxyapatite.

[0045] S3: Under nitrogen protection, add 500 ml of anhydrous ethanol, 100 g of chitosan-modified silane hydroxyapatite, and 5 ml of glacial acetic acid to the reactor. Heat to 35°C and stir for 20 min. Slowly add 100 ml of deionized water containing 25 g of mercaptopolyethylene glycol amino (SH-PEG-NH2, number average molecular weight of 1000) dropwise over 20 min. After the addition is complete, heat to 70°C and react for 8 h. Then cool to room temperature and adjust the pH to neutral with 5 wt% NaOH solution. Pour the reaction solution into 800 ml of acetone, stir to precipitate, filter, wash three times with acetone (300 ml of acetone each time), and vacuum dry at 50°C for 12 h to obtain polyethylene glycol-modified hydroxyapatite.

[0046] S4: Add 500ml of phosphate buffer (0.1M, pH=8.5) and 100g of polyethylene glycol modified hydroxyapatite to the reactor and stir for 2h. Dissolve 2g of borax pentahydrate in 20mL of 50℃ deionized water and stir until completely dissolved. Slowly add the solution dropwise to the reactor over 20min. After the addition is complete, raise the temperature to 60℃ and react for 3h. Add 0.5M HCl to adjust the pH to 7.0. Then add 20ml of glycerol and 80ml of deionized water and stir to mix well to obtain the composite binder.

[0047] Example 4 The preparation method of the oxidized chitosan used in Examples 1-3 is as follows:

[0048] 4 g of chitosan (number average molecular weight of 25,000 Daltons) and 6 g of sodium periodate were dispersed in 50 mL of phosphate buffer solution (0.1 M, pH=7.4) and stirred for 30 min to dissolve completely. Then, stirring was continued for 12 h in the dark at room temperature. 1.5 mL of ethylene glycol was added to the mixture and stirring was continued for 3 h to terminate the reaction. The mixture was then transferred to a dialysis bag (8000 Da) and dialyzed in deionized water for 2 days, with 2000 mL of water changed every 6 h. The mixture was then freeze-dried at -40 °C for 36 h to obtain oxidized chitosan.

[0049] Example 5: Preparation of environmentally friendly ceramics:

[0050] (1) Weigh out: 300g red mud, 200g fly ash, 100g purple clay, 50g quartz, 30g composite binder (prepared in Example 1), 30g composite flux (12g spodumene, 18g waste glass powder), and 400g deionized water;

[0051] (2) Dry the red mud and fly ash at 105℃ for 6 hours. Then put the red mud, fly ash, purple clay, quartz, composite binder and composite flux into a ball mill, add deionized water, use grinding balls with a diameter of 5 mm and 3 mm, the weight ratio of 5 mm grinding balls to 3 mm grinding balls is 2:1, the ball-to-material ratio is 15:1, ball mill at 600 rpm for 15 min, stand for 15 min, circulate ball milling and stand for 8 times, and pass through a 200 mesh sieve to obtain a uniform slurry;

[0052] (3) The slurry is spray-granulated using a pressure nozzle at a rotation speed of 15,000 rpm, a feed rate of 10 L / h, an atomization pressure of 2.5 MPa, an inlet air temperature of 200℃, and a hot air flow rate of 120 m³ / h. 3 The air outlet temperature is controlled at 90-100℃ to obtain granular powder. The powder is aged in a sealed environment for 24 hours. The aged powder is placed in a mold (3mm×3mm×30mm) and held under pressure of 20MPa for 15 minutes to obtain green body. The green body is placed in a sintering furnace and heated from room temperature to 450℃ at a rate of 5℃ / min and held for 40 minutes. Then the temperature is increased to 1080℃ at a rate of 5℃ / min and held for 60 minutes. Finally, the furnace is cooled to room temperature to obtain environmentally friendly ceramics.

[0053] Example 6: Preparation of environmentally friendly ceramics:

[0054] (1) Weigh out: 400g red mud, 300g fly ash, 180g purple clay, 100g quartz, 50g composite binder (prepared in Example 2), 60g composite flux (20g spodumene, 40g waste glass powder), and 450g deionized water;

[0055] (2) Dry the red mud and fly ash at 110℃ for 5 hours. Then put the red mud, fly ash, purple clay, quartz, composite binder and composite flux into a ball mill, add deionized water, use grinding balls with a diameter of 5 mm and 3 mm, the weight ratio of 5 mm grinding balls to 3 mm grinding balls is 2:1, the ball-to-material ratio is 15:1, ball mill at 500 rpm for 15 min, stand for 15 min, circulate ball milling and stand for 8 times, and pass through a 200 mesh sieve to obtain a uniform slurry.

[0056] (3) The slurry is spray-granulated using a pressure nozzle at a rotation speed of 15,000 rpm, a feed rate of 10 L / h, an atomization pressure of 2.5 MPa, an inlet air temperature of 200℃, and a hot air flow rate of 120 m³ / h. 3The air outlet temperature is controlled at 90-100℃ to obtain granular powder. The powder is aged in a sealed environment for 32 hours. The aged powder is placed in a mold (3mm×3mm×30mm) and held under pressure of 25MPa for 15 minutes to obtain green body. The green body is placed in a sintering furnace and heated from room temperature to 480℃ at a rate of 5℃ / min and held for 35 minutes. Then the temperature is increased to 1100℃ at a rate of 5℃ / min and held for 40 minutes. Finally, the furnace is cooled to room temperature to obtain environmentally friendly ceramics.

[0057] Example 7: Preparation of environmentally friendly ceramics:

[0058] (1) Weigh out: 500g red mud, 400g fly ash, 250g purple clay, 150g quartz, 80g composite binder (prepared in Example 3), 80g composite flux (23g spodumene, 57g waste glass powder), and 500g deionized water;

[0059] (2) Dry the red mud and fly ash at 120℃ for 4 hours. Then put the red mud, fly ash, purple clay, quartz, composite binder and composite flux into a ball mill, add deionized water, use grinding balls with a diameter of 5 mm and 3 mm, the weight ratio of 5 mm grinding balls to 3 mm grinding balls is 2:1, the ball-to-material ratio is 15:1, ball mill at 400 rpm for 15 min, stand for 15 min, circulate ball milling and stand for 8 times, and pass through a 200 mesh sieve to obtain a uniform slurry;

[0060] (3) The slurry is spray-granulated using a pressure nozzle at a rotation speed of 15,000 rpm, a feed rate of 10 L / h, an atomization pressure of 2.5 MPa, an inlet air temperature of 200℃, and a hot air flow rate of 120 m³ / h. 3 The air outlet temperature is controlled at 90-100℃ to obtain granular powder. The powder is aged in a sealed environment for 48 hours. The aged powder is placed in a mold (3mm×3mm×30mm) and held under pressure of 30MPa for 15 minutes to obtain green body. The green body is placed in a sintering furnace and heated from room temperature to 500℃ at a rate of 5℃ / min and held for 30 minutes. Then the temperature is increased to 1150℃ at a rate of 5℃ / min and held for 30 minutes. Finally, the furnace is cooled to room temperature to obtain environmentally friendly ceramics.

[0061] Comparative Example 1

[0062] An environmentally friendly ceramic, with the same raw material composition and preparation method as in Example 6, differs in that the composite binder is replaced with an equal weight of a composite binder prepared by the following method:

[0063] The preparation method of the composite adhesive is basically the same as that in Example 2, except that 3-aminopropyltriethoxysilane in step S1 is replaced with an equal weight of (3-aminopropyl)dimethylethoxysilane.

[0064] Comparative Example 2

[0065] An environmentally friendly ceramic, with the same raw material composition and preparation method as in Example 6, differs in that the composite binder is replaced with an equal weight of a composite binder prepared by the following method:

[0066] The preparation method of the composite adhesive is basically the same as that in Example 2, except that the oxidized chitosan in step S2 is replaced with an equal weight of oxidized dextran.

[0067] Comparative Example 3

[0068] An environmentally friendly ceramic, with the same raw material composition and preparation method as in Example 6, differs in that the composite binder is replaced with an equal weight of a composite binder prepared by the following method:

[0069] The preparation method of the composite adhesive is basically the same as that in Example 2, except that the mercapto polyethylene glycol amino in step S3 is replaced with an equal weight of mercapto polyethylene glycol amino with a number average molecular weight of 3000.

[0070] Comparative Example 4

[0071] An environmentally friendly ceramic, with the same raw material composition and preparation method as in Example 6, differs in that the composite binder is replaced with an equal weight of a composite binder prepared by the following method:

[0072] The preparation method of the composite adhesive is basically the same as that in Example 2, except that the mercapto polyethylene glycol amino in step S3 is replaced with an equal weight of polyethylene glycol amino (PEG-NH2, number average molecular weight of 1000).

[0073] Comparative Example 5

[0074] An environmentally friendly ceramic, with the same raw material composition and preparation method as in Example 6, differs in that the composite binder is replaced with an equal weight of a composite binder prepared by the following method:

[0075] The preparation method of the composite adhesive is basically the same as that of Example 2, except that the composite adhesive is replaced with an equal weight of polyethylene glycol modified hydroxyapatite prepared by step S3 of Example 2.

[0076] Comparative Example 6

[0077] An environmentally friendly ceramic, with the same raw material composition and preparation method as in Example 6, differs in that the composite binder is replaced with an equal weight of a composite binder prepared by the following method:

[0078] S1: Weigh 2g of 3-aminopropyltriethoxysilane, add 20ml of deionized water, and stir at 40℃ for 3h to obtain 3-aminopropylsilanetriol; add 100g of hydroxyapatite to 500ml of 50wt% ethanol aqueous solution, and sonicate for 15min to obtain hydroxyapatite dispersion; under nitrogen protection, slowly add 3-aminopropylsilanetriol dropwise to hydroxyapatite dispersion over 20min, and after the addition is complete, heat to 90℃, react for 8h, cool to room temperature, filter, wash 3 times with deionized water (200ml of deionized water each time), vacuum dry at 60℃ for 5h, grind and pulverize, and pass through an 80-mesh sieve to obtain silane-modified hydroxyapatite;

[0079] S2: Under nitrogen protection, 500 ml of anhydrous ethanol, 100 g of silane-modified hydroxyapatite, and 5 ml of glacial acetic acid were added to the reactor. The temperature was raised to 35°C and stirred for 20 min. 100 ml of 1 wt% acetic acid aqueous solution containing 20 g of oxidized chitosan was slowly added dropwise over 20 min. After the addition was complete, the temperature was raised to 65°C and reacted for 9 h. The temperature was then lowered to room temperature, and the pH was adjusted to neutral with 5 wt% NaOH solution. The reaction solution was poured into 800 ml of acetone, stirred to precipitate, filtered, and washed three times with acetone (300 ml of acetone each time). The mixture was then vacuum dried at 45°C for 12 h to obtain chitosan-modified silane hydroxyapatite.

[0080] S3: Add 500ml of PBS buffer (phosphate buffer) (0.1M, pH=8.5) and 100g of chitosan-modified silane hydroxyapatite to the reactor and stir for 2h. Dissolve 2g of borax pentahydrate in 20mL of 50℃ deionized water and stir until completely dissolved. Slowly add the solution dropwise to the reactor over 20min. After the addition is complete, raise the temperature to 55℃ and react for 4h. Add 0.5M HCl to adjust the pH to 7.0. Then add 20ml of glycerol and 80ml of deionized water and stir to mix well to obtain the composite binder.

[0081] The red mud used in the embodiments and comparative examples of this application mainly consists of silicon dioxide (25.43 wt%), aluminum oxide (17.36 wt%), ferric oxide (17.04 wt%), and calcium oxide (36.46 wt%), with a particle size uniformly distributed between 80 and 100 mesh; the fly ash mainly consists of silicon dioxide (54.9 wt%), aluminum oxide (26.4 wt%), ferric oxide (11.2 wt%), and calcium oxide (5.8 wt%), with a particle size uniformly distributed between 20 and 40 mesh; the purple clay is Xinjin purple clay (sand content 69.5 wt%, calcium carbonate content 7.8 wt%); the quartz is 140 mesh and comes from Inner Mongolia Changfan Quartz Sand Co., Ltd.; the hydroxyapatite is model HAP07-E and comes from Nanjing Junzhuo Biotechnology Co., Ltd.; the waste glass powder has a particle size of 400 mesh; and the spodumene has a particle size of 300 mesh.

[0082] The preparation method of the oxidized dextran used in Comparative Example 2 is as follows:

[0083] 4 g of dextran (β-glucan, number average molecular weight of 20,000 Daltons) and 6 g of sodium periodate were dispersed in 50 mL of phosphate buffer solution (0.1 M, pH=7.4) and stirred for 30 min to dissolve completely. Then, stirring was continued for 12 h in the dark at room temperature. 1.5 mL of ethylene glycol was added to the mixture and stirring was continued for 3 h to terminate the reaction. The mixture was then transferred to a dialysis bag (8000 Da) and dialyzed in deionized water for 2 days, with 2000 mL of water changed every 6 h. The mixture was then freeze-dried at -40 °C for 36 h to obtain oxidized dextran.

[0084] The green bodies prepared in step (3) of Examples 5-7 and Comparative Examples 1-6 and the finally prepared environmentally friendly ceramics were tested for flexural strength and apparent porosity. The results are shown in Table 1.

[0085] Flexural strength test: The flexural strength of the samples was determined using a KZJ-30 electric flexural strength tester. The calculation formula is as follows:

[0086] In the formula, —Flexural strength ;

[0087] P—The load (N) at which the specimen breaks;

[0088] L—Distance between support blades (mm), 30mm in this experiment;

[0089] B—Width of the fracture surface of the sample (mm);

[0090] H—Height at the fracture surface of the sample (mm);

[0091] K—coefficient, take K=1.

[0092] Apparent porosity test: The cleaned and finalized environmentally friendly ceramic was placed in a drying oven and dried at 110℃ ± 5℃ to constant weight. It was then placed in a desiccator to cool to room temperature, and the dry weight of the sample (m1) was measured to an accuracy of 0.001g. The dried sample was placed in a vacuum container, and the vacuum pump was started to ensure the residual pressure in the vacuum container was less than 2500Pa. The sample was held at this vacuum level for 15 minutes. The stopcock between the vacuum container and the storage bottle was opened, and distilled water was injected, increasing the water level to 20mm above the sample within 3 minutes. Vacuuming continued for 30 minutes, and then the vacuum pump was turned off to restore the vacuum container to atmospheric pressure. The sample was then immersed at atmospheric pressure for 30 minutes. The immersed saturated sample was placed in a basket and suspended in a container filled with distilled water and equipped with an overflow pipe. The suspended mass of the saturated sample in the distilled water (m2) was weighed to an accuracy of 0.001g. Select pure cotton towels according to GB / T29862, cut them into squares with sides of 14cm, soak them in distilled water for 5 minutes, remove them and fold them into squares with sides of 7cm. Lay them flat under the press head and apply pressure. The press head should completely cover the towel. Hold the pressure at 3.3kN±0.2kN for 10 seconds. Wipe away any liquid drained around the press head with a clean cotton cloth, then remove the towel containing distilled water. Remove the sample from the distilled water, wipe away any liquid adhering to the sample surface with the towel soaked in distilled water, and weigh the saturated sample in air (m3) within 30 seconds, accurate to 0.001g. The basket is made of 0.2mm diameter metal wire and used to weigh the saturated distilled water sample. The suspension wire is a clean, inelastic 0.2mm diameter wire. Calculate the apparent porosity using the following formula: q=(m3-m1) / (m3-m2)×100%.

[0093] Table 1 Performance Indicators of Environmentally Friendly Ceramics

[0094]

[0095] As can be seen from the data in Examples 5, 6, and 7 of Table 1, the environmentally friendly ceramics prepared in this application have excellent flexural strength and apparent porosity.

[0096] The environmentally friendly ceramics prepared in this invention incorporate a composite binder based on hydroxyapatite, introducing hydroxyl groups, dynamically reversible Schiff base bonds, borate ester bonds, and thiol groups. Unreacted hydroxyl groups on the chitosan chains in the composite binder can form strong hydrogen bonds with other ceramic particles, enhancing the strength of the green body. The interpenetration and entanglement of long polyethylene glycol chains effectively fill the gaps between ceramic particles, and their flexibility and lubricity reduce stress concentration during sintering, inhibiting microcrack propagation. The dynamic Schiff base bonds in the composite binder can undergo reversible breakage and recombination during green body processing, effectively dissipating stress and promoting particle rearrangement, thereby reducing local stress concentration. The borate ester bonds also possess dynamic reversibility, adjusting the viscoelasticity of the bonding network through ester bond breakage and regeneration, enhancing the deformation adaptability of the green body during forming. The synergistic effect of the dynamic bonds not only improves the interfacial bonding between ceramic particles but also effectively inhibits microcrack propagation through the energy dissipation mechanism of reversible bonds. The thiol groups in the composite binder undergo oxidation at high temperatures to form disulfide bonds, further constructing a dynamic cross-linked network and improving the toughness and structural stability of the ceramic. The synergistic effect of multiple functional groups significantly enhances the bonding strength and stress dissipation capacity between green body particles; at the same time, through the steric hindrance effect and network filling effect, it promotes the uniform dispersion of particles and effectively fills the pores, ultimately forming a dense structure and environmentally friendly ceramic with excellent mechanical properties.

[0097] In Comparative Example 4, the main reason for the decrease in flexural strength and increase in apparent porosity after replacing mercapto-polyethylene glycol amino groups with polyethylene glycol amino groups was the absence of a disulfide bond crosslinking network. Polyethylene glycol amino groups can only participate in crosslinking through Schiff base reactions and cannot be oxidized to form dynamic disulfide bonds, resulting in a significant reduction in the crosslinking density of the three-dimensional network, ultimately leading to a decrease in the flexural strength of the ceramic.

[0098] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. However, any modifications, alterations, and variations made by those skilled in the art without departing from the scope of the present invention based on the disclosed technical content are equivalent embodiments of the present invention. Furthermore, any modifications, alterations, and variations made to the above embodiments based on the essential technology of the present invention are still within the protection scope of the present invention.

Claims

1. An environmentally friendly ceramic, characterized in that, The ingredients include the following parts by weight: Red mud 30-50 parts, fly ash 20-40 parts, purple clay 10-25 parts, quartz 5-15 parts, composite binder 3-8 parts, composite flux 3-8 parts, deionized water 40-50 parts; The composite adhesive is prepared by the following method: S1: Weigh 3-aminopropyltriethoxysilane, add deionized water, and stir to obtain 3-aminopropylsilanetriol; add hydroxyapatite to an ethanol aqueous solution and ultrasonically disperse to obtain a hydroxyapatite dispersion; under nitrogen protection, slowly add 3-aminopropylsilanetriol to the hydroxyapatite dispersion, heat to react, cool, filter, wash with deionized water, vacuum dry, grind and pulverize, and sieve to obtain silane-modified hydroxyapatite; S2: Under nitrogen protection, anhydrous ethanol, silane-modified hydroxyapatite, and glacial acetic acid were added to the reactor. The mixture was heated and stirred. An aqueous solution of acetic acid containing oxidized chitosan was added dropwise. The mixture was heated and reacted. The temperature was lowered to room temperature. The pH was adjusted to neutral with NaOH solution. The reaction solution was poured into acetone and stirred to precipitate. The precipitate was filtered, washed with acetone, and dried under vacuum to obtain chitosan-modified silane hydroxyapatite. S3: Under nitrogen protection, anhydrous ethanol, chitosan-modified silane hydroxyapatite, and glacial acetic acid were added to the reactor. The mixture was heated and stirred. A deionized aqueous solution of mercaptopolyethylene glycol amino was added dropwise. The mixture was heated and reacted. The mixture was cooled to room temperature and the pH was adjusted to neutral with NaOH solution. The reaction solution was poured into acetone and stirred to precipitate. The precipitate was filtered, washed three times with acetone, and dried under vacuum to obtain polyethylene glycol-modified hydroxyapatite. S4: Add phosphate buffer and polyethylene glycol modified hydroxyapatite to the reactor, stir, dissolve borax pentahydrate in deionized water, stir until completely dissolved, slowly add it dropwise to the reactor, heat the reaction, add HCl to adjust the pH to 7.0, then add glycerol and deionized water and stir to mix well to obtain the composite binder; The preparation method of the oxidized chitosan is as follows: Chitosan and sodium periodate were dispersed in a phosphate buffer solution and stirred until completely dissolved. Then, stirring was continued in the dark at room temperature. Ethylene glycol was added and stirring was continued to terminate the reaction. The mixture was then transferred to a dialysis bag and dialyzed in deionized water. After freeze-drying, oxidized chitosan was obtained. The composite flux is a mixture of spodumene and waste glass powder.

2. The environmentally friendly ceramic according to claim 1, characterized in that, In step S1, the mass ratio of hydroxyapatite to 3-aminopropyltriethoxysilane is 100:(1-3).

3. The environmentally friendly ceramic according to claim 1, characterized in that, In step S2, the mass ratio of silane-modified hydroxyapatite to oxidized chitosan is 10:(1-3).

4. The environmentally friendly ceramic according to claim 1, characterized in that, In step S3, the mass ratio of chitosan-modified silane hydroxyapatite to mercapto-polyethylene glycol amino is 10:(1-2.5).

5. The environmentally friendly ceramic according to claim 1, characterized in that, In step S4, the mass ratio of polyethylene glycol-modified hydroxyapatite to borax pentahydrate is 100:(2-3).

6. The environmentally friendly ceramic according to claim 1, characterized in that, The weight ratio of spodumene to waste glass powder is 1:(1.5-2.5).

7. A method for preparing the environmentally friendly ceramic according to any one of claims 1-6, characterized in that, Includes the following steps: (1) Weigh out the following by weight: 30-50 parts red mud, 20-40 parts fly ash, 10-25 parts purple clay, 5-15 parts quartz, 3-8 parts composite binder, 3-8 parts composite flux, and 40-50 parts deionized water. (2) Dry the red mud and fly ash, and then pass them through a 100-mesh sieve; put the red mud, fly ash, purple clay, quartz, composite binder and composite flux into a ball mill, add deionized water, ball mill, and pass through a 200-mesh sieve to obtain a uniform slurry; (3) Spray granulation of the slurry to obtain granular powder; after aging the powder in a closed environment for 24-48 hours, place it in a mold and press it to form a green body; place the green body in a sintering furnace, raise the temperature from room temperature to 450-500℃ and hold it for 30-40 minutes; then raise the temperature to 1080℃-1150℃ and hold it for 30-60 minutes; finally cool it to room temperature to obtain environmentally friendly ceramics.

Images