Environment-friendly ceramic and preparation method thereof

Abstract

The invention discloses environment-friendly ceramic and a preparation method thereof, and belongs to the technical field of ceramic. 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 clay, 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 disclosed by the invention has excellent breaking strength and apparent porosity.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ceramics, in particular to an environment-friendly ceramic and a preparation method thereof. BACKGROUND

[0002] In the traditional ceramic preparation process, the mechanical properties (such as the bending strength) of the green body are the key initial factors affecting the final performance of the ceramic product after sintering. As the initial form before sintering, the bonding state between the internal particles, the pore structure and the overall uniformity of the green body directly determine the mechanical properties of the product in the subsequent sintering process.

[0003] However, the currently widely used organic binder still has some deficiencies in the forming of the ceramic green body. On the one hand, the bonding force between the binder and the ceramic particles is weak, resulting in low initial strength of the green body, which is prone to breakage or micro-crack propagation during handling, processing or pre-treatment before sintering, thereby causing a decrease in the yield of finished products. On the other hand, the organic binder will decompose and volatilize during the removal stage before high-temperature sintering, leaving many pores. Too many pores or uneven distribution of pores will hinder the material transport during the sintering process and inhibit the uniform migration of the grain boundary, resulting in insufficient densification and possibly causing abnormal grain growth, ultimately leading to uneven microstructure, which causes problems such as high brittleness and poor reliability in the actual application of the ceramic product. Therefore, it has become a key problem in the ceramic field to develop an environment-friendly ceramic with excellent bending strength and apparent porosity. SUMMARY

[0004] In view of the deficiencies of the prior art, the purpose of the present application is to provide an environment-friendly ceramic and a preparation method thereof.

[0005] To achieve the above-mentioned purpose, the present application realizes the following technical scheme: An 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 composite binder is prepared by the following method: S1: hydroxyapatite is reacted with 3-aminopropyl triethoxysilane to generate silane-modified hydroxyapatite, S2: the silane-modified hydroxyapatite is reacted with oxidized chitosan under the action of a catalyst to generate chitosan-modified silane hydroxyapatite, S3: the chitosan-modified silane hydroxyapatite is reacted with mercapto polyethylene glycol amino under the action of a catalyst to generate polyethylene glycol-modified hydroxyapatite, S4: the polyethylene glycol-modified hydroxyapatite is reacted with borax pentahydrate to generate the composite binder.

[0006] In step S1, the mass ratio of hydroxyapatite to 3-aminopropyl triethoxysilane is 100:(1-3).

[0007] In step S2, the mass ratio of silane-modified hydroxyapatite to oxidized chitosan is 10:(1-3).

[0008] In step S3, the mass ratio of chitosan-modified silane hydroxyapatite to mercapto polyethylene glycol amino is 10:(1-2.5).

[0009] In step S4, the mass ratio of polyethylene glycol-modified hydroxyapatite to borax pentahydrate is 100:(2-3).

[0010] The composite flux is a mixture of spodumene and waste glass powder.

[0011] The mixing weight ratio of spodumene to waste glass powder is 1:(1.5-2.5).

[0012] In step S2, the catalyst is glacial acetic acid.

[0013] In step S3, the catalyst is glacial acetic acid.

[0014] A preparation method of an environment-friendly ceramic, comprising the following steps: (1) Take by weight parts: 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 composite binder, 3-8 parts of composite flux, and 40-50 parts of deionized water; (2) Dry the red mud and fly ash, and then pass through a 100-mesh sieve; put the red mud, fly ash, purple sand soil, 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 in a sealed environment for 24-48 h, the powder is placed in a mold and compression molded to obtain a green body; the green body is placed in a sintering furnace, heated from room temperature to 450-500°C, and kept for 30-40 min; then heated to 1080-1150°C, and kept for 30-60 min; finally cooled to room temperature to obtain the environment-friendly ceramic.

[0015] Due to the adoption of the above technical solutions, the present application has the following advantages: The environment-friendly ceramic prepared by the present application has excellent bending strength and apparent porosity. DETAILED DESCRIPTION

[0016] The present application will be further described below in conjunction with examples, but the present application is not limited to these examples.

[0017] Preparation of composite binder of Example 1: S1: 1 g of 3-aminopropyltriethoxysilane was weighed, added to 20 ml of deionized water, and stirred at 40°C for 3 h to obtain 3-aminopropylsilanetriol; 100 g of hydroxyapatite was added to 500 ml of 50 wt% aqueous ethanol solution, and ultrasonically dispersed for 15 min to obtain a hydroxyapatite dispersion; under nitrogen protection, the 3-aminopropylsilanetriol was slowly added dropwise to the hydroxyapatite dispersion, and after 20 min of dropping, the temperature was raised to 90°C, and reacted for 8 h, and then cooled to room temperature, filtered, washed with deionized water three times (200 ml of deionized water was used each time), vacuum dried at 60°C for 10 h, ground and pulverized, and passed through an 80-mesh sieve to obtain silane-modified hydroxyapatite; the reaction equation is as follows: wherein, is the schematic formula of hydroxyapatite, and the surface of the hydroxyapatite is rich in a large number of hydroxyl groups, which are condensed with silanol obtained by hydrolysis of the silane coupling agent to form a Si-O-P covalent bond.

[0018] 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 a reactor, the temperature was raised to 35°C and stirred for 20 min, 100 ml of a 1 wt% aqueous acetic acid solution containing 10 g of oxidized chitosan was slowly added dropwise, and after 20 min of dropping, the temperature was raised to 60°C and reacted for 10 h, and then cooled to room temperature, the pH was adjusted to neutral with a 5 wt% NaOH solution, the reaction liquid was poured into 800 ml of acetone, and the precipitate was stirred and separated, filtered, washed with acetone three times (300 ml of acetone was used each time), and vacuum dried at 45°C for 12 h to obtain chitosan-modified silane hydroxyapatite; the reaction equation is as follows:

[0019] 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 a reactor, the temperature was raised to 35°C and stirred for 20 min, 100 ml of a deionized water solution containing 10 g of mercapto polyethylene glycol amino (SH-PEG-NH2, number average molecular weight 1000) was slowly added dropwise, and after 20 min of dropping, the temperature was raised to 60°C and reacted for 10 h, and then cooled to room temperature, the pH was adjusted to neutral with a 5 wt% NaOH solution, the reaction liquid was poured into 800 ml of acetone, and the precipitate was stirred and separated, filtered, washed with acetone three times (300 ml of acetone was used each time), and vacuum dried at 50°C for 12 h to obtain polyethylene glycol-modified hydroxyapatite; the reaction equation is as follows:

[0020] S4: 500 ml of phosphate buffer (0.1 M, pH = 8.5) and 100 g of polyethylene glycol modified hydroxyapatite were added into the reactor, stirred for 2 h, 2 g of borax pentahydrate was dissolved in 20 mL of 50 °C deionized water, stirred until completely dissolved, slowly added into the reactor, dropwise added for 20 min, after dropping, the temperature was raised to 50 °C and reacted for 5 h, 0.5 M HCl was added to adjust the pH to 7.0, then 20 ml of glycerol and 80 ml of deionized water were added and stirred to obtain a composite adhesive.

[0021] Example 2 Preparation of composite adhesive: S1: 2 g of 3-aminopropyltriethoxysilane was weighed, added into 20 ml of deionized water, and stirred at 40 °C for 3 h to obtain 3-aminopropylsilanetriol; 100 g of hydroxyapatite was added into 500 ml of 50 wt% aqueous ethanol solution, ultrasonically dispersed for 15 min to obtain a hydroxyapatite dispersion; under nitrogen protection, the 3-aminopropylsilanetriol was slowly added into the hydroxyapatite dispersion, dropwise added for 20 min, after dropping, the temperature was raised to 90 °C and reacted for 8 h, then cooled to room temperature, filtered, washed with deionized water for 3 times (200 ml of deionized water was used each time), vacuum dried at 60 °C for 10 h, ground and crushed, and passed through an 80 mesh sieve to obtain silane modified hydroxyapatite; S2: under nitrogen protection, 500 ml of anhydrous ethanol, 100 g of silane modified hydroxyapatite and 5 ml of glacial acetic acid were added into the reactor, the temperature was raised to 35 °C and stirred for 20 min, 100 ml of 1 wt% aqueous acetic acid solution containing 20 g of oxidized chitosan was slowly added, dropwise added for 20 min, after dropping, the temperature was raised to 65 °C and reacted for 9 h, then cooled to room temperature, the pH was adjusted to neutral with 5 wt% NaOH solution, the reaction liquid was poured into 800 ml of acetone, the precipitate was stirred and separated, filtered, washed with acetone for 3 times (300 ml of acetone was used each time), and vacuum dried at 45 °C for 12 h to obtain chitosan modified silane hydroxyapatite; 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 into the reactor, the temperature was raised to 35 °C and stirred for 20 min, 100 ml of deionized water containing 18 g of mercapto polyethylene glycol amino (SH-PEG-NH2, number average molecular weight of 1000) was slowly added, dropwise added for 20 min, after dropping, the temperature was raised to 65 °C and reacted for 9 h, then cooled to room temperature, the pH was adjusted to neutral with 5 wt% NaOH solution, the reaction liquid was poured into 800 ml of acetone, the precipitate was stirred and separated, filtered, washed with acetone for 3 times (300 ml of acetone was used each time), and vacuum dried at 50 °C for 12 h to obtain polyethylene glycol modified hydroxyapatite; S4: 500 ml of phosphate buffer (0.1 M, pH = 8.5) and 100 g of polyethylene glycol modified hydroxyapatite were added into the reactor, stirred for 2 h, 2 g of borax pentahydrate was dissolved in 20 mL of 50 °C deionized water, stirred until completely dissolved, slowly added into the reactor, dropwise added for 20 min, after dropping, the temperature was raised to 55 °C and reacted for 4 h, 0.5 M HCl was added to adjust the pH to 7.0, then 20 ml of glycerol and 80 ml of deionized water were added and stirred to obtain a composite adhesive.

[0022] Example 3 Preparation of composite adhesive: S1: 3 g of 3-aminopropyltriethoxysilane was weighed, added into 20 ml of deionized water, and stirred at 40 °C for 3 h to obtain 3-aminopropylsilanetriol; 100 g of hydroxyapatite was added into 500 ml of 50 wt% aqueous ethanol solution, ultrasonically dispersed for 15 min to obtain a hydroxyapatite dispersion; under nitrogen protection, the 3-aminopropylsilanetriol was slowly added into the hydroxyapatite dispersion, dropwise added for 20 min, after dropping, the temperature was raised to 90 °C and reacted for 8 h, then cooled to room temperature, filtered, washed with deionized water for 3 times (200 ml of deionized water was used each time), vacuum dried at 60 °C for 10 h, ground and crushed, and passed through an 80 mesh sieve to obtain silane modified hydroxyapatite; S2: under nitrogen protection, 500 ml of anhydrous ethanol, 100 g of silane modified hydroxyapatite and 5 ml of glacial acetic acid were added into the reactor, the temperature was raised to 35 °C and stirred for 20 min, 100 ml of 1 wt% aqueous acetic acid solution containing 30 g of oxidized chitosan was slowly added, dropwise added for 20 min, after dropping, the temperature was raised to 70 °C and reacted for 8 h, then cooled to room temperature, the pH was adjusted to neutral with 5 wt% NaOH solution, the reaction liquid was poured into 800 ml of acetone, the precipitate was stirred and separated, filtered, washed with acetone for 3 times (300 ml of acetone was used each time), and vacuum dried at 45 °C for 12 h to obtain chitosan modified silane hydroxyapatite; 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 into the reactor, the temperature was raised to 35 °C and stirred for 20 min, 100 ml of deionized water containing 25 g of mercapto polyethylene glycol amino (SH-PEG-NH2, number average molecular weight of 1000) was slowly added, dropwise added for 20 min, after dropping, the temperature was raised to 70 °C and reacted for 8 h, then cooled to room temperature, the pH was adjusted to neutral with 5 wt% NaOH solution, the reaction liquid was poured into 800 ml of acetone, the precipitate was stirred and separated, filtered, washed with acetone for 3 times (300 ml of acetone was used each time), and vacuum dried at 50 °C for 12 h to obtain polyethylene glycol modified hydroxyapatite; S4: 500 ml of phosphate buffer (0.1 M, pH = 8.5) and 100 g of polyethylene glycol modified hydroxyapatite were added to the reactor, stirred for 2 h, 2 g of borax pentahydrate was dissolved in 20 mL of 50 °C deionized water, stirred until completely dissolved, slowly added to the reactor, dropwise added for 20 min, after dropping, the temperature was raised to 60 °C and reacted for 3 h, 0.5 M HCl was added to adjust the pH to 7.0, then 20 ml of glycerol and 80 ml of deionized water were added and stirred to obtain a composite adhesive.

[0023] The preparation method of the oxidized chitosan used in examples 1-3 is as follows: 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), stirred for 30 min to completely dissolve; then continue to stir in the dark at room temperature for 12 h, 1.5 mL of ethylene glycol was added to the above mixed solution, continue to stir for 3 h to terminate the reaction, then transfer into a dialysis bag (8000 Da), and dialyze in deionized water for 2 days, change water every 6 h, 2000 ml each time, freeze-dried at -40 °C for 36 h to obtain oxidized chitosan.

[0024] Example 5: Preparation of environmentally friendly ceramics: (1) Take: red mud 300 g, fly ash 200 g, purple clay 100 g, quartz 50 g, composite adhesive (prepared in example 1) 30 g, composite flux (12 g of spodumene, 18 g of waste glass powder) 30 g, deionized water 400 g; (2) The red mud and fly ash were dried at 105 °C for 6 h, then the red mud, fly ash, purple clay, quartz, composite adhesive and composite flux were put into a ball mill, deionized water was added, 5 mm diameter grinding balls and 3 mm grinding balls were used, the weight ratio of 5 mm grinding balls to 3 mm grinding balls was 2:1, the ball-to-material ratio was 15:1, the ball milling speed was 600 rpm, the ball milling time was 15 min, the static time was 15 min, the cycle ball milling and static time was 8 times, and the uniform slurry was obtained by passing through a 200 mesh sieve; (3) The slurry was spray granulated, the nozzle was a pressure nozzle, the rotating speed was 15000 rpm, the feeding rate was 10 L / h, the atomization pressure was 2.5 MPa, the inlet air temperature was 200 °C, the hot air flow was 120 m 3The 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.

[0025] Example 6: Preparation of environmentally friendly ceramics: (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; (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. (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 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.

[0026] Example 7: Preparation of environmentally friendly ceramics: (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; (2) The red mud and fly ash are dried at 120 °C for 4 h, respectively. Then the red mud, fly ash, purple clay, quartz, composite binder and composite fluxing agent are put into a ball mill, and deionized water is added. The ball mill uses 5 mm diameter grinding balls and 3 mm diameter grinding balls, with a weight ratio of 5 mm grinding balls to 3 mm grinding balls of 2:1, a ball-to-material ratio of 15:1, 400 rpm ball milling for 15 min, 15 min of static, 8 cycles of ball milling and static, and a 200 mesh sieve to obtain a uniform slurry; (3) The slurry is spray granulated using a pressure nozzle at a speed of 15000 rpm, a feeding rate of 10 L / h, an atomization pressure of 2.5 MPa, an air inlet temperature of 200 °C, a hot air flow rate of 120 m 3 / min, and an air outlet temperature controlled at 90-100 °C to obtain granular powder. The powder is aged in a sealed environment for 48 h. The aged powder is placed in a mold (3 mm x 3 mm x 30 mm) and pressed at a pressure of 30 MPa for 15 min to obtain a green body. The green body is placed in a sintering furnace and heated from room temperature to 500 °C at a rate of 5 °C / min and held for 30 min. Then it is heated to 1150 °C at a rate of 5 °C / min and held for 30 min. Finally, it is cooled to room temperature with the furnace to obtain the environment-friendly ceramic.

[0027] Comparative Example 1 An environment-friendly ceramic, the raw material composition and preparation method of which are basically the same as those of Example 6, except that the composite binder is replaced by an equal weight of a composite binder prepared by the following method: The preparation method of the composite binder is basically the same as that of Example 2, except that the 3-aminopropyltriethoxysilane in step S1 is replaced by an equal weight of (3-aminopropyl)dimethylethoxysilane.

[0028] Comparative Example 2 An environment-friendly ceramic, the raw material composition and preparation method of which are basically the same as those of Example 6, except that the composite binder is replaced by an equal weight of a composite binder prepared by the following method: The preparation method of the composite binder is basically the same as that of Example 2, except that the oxidized chitosan in step S2 is replaced by an equal weight of oxidized dextran.

[0029] Comparative Example 3 An environment-friendly ceramic, the raw material composition and preparation method of which are basically the same as those of Example 6, except that the composite binder is replaced by an equal weight of a composite binder prepared by the following method: The preparation method of the composite binder is basically the same as that of Example 2, except that the mercapto polyethylene glycol amino in step S3 is replaced by an equal weight of mercapto polyethylene glycol amino with a number average molecular weight of 3000.

[0030] Comparative Example 4 An environmentally friendly ceramic, the raw material composition and preparation method are basically the same as Example 6, the difference is that the composite binder is replaced by equal weight of the composite binder prepared by the following method: The preparation method of the composite binder is basically the same as Example 2, the difference is that the mercapto polyethylene glycol amino in step S3 is replaced by equal weight of polyethylene glycol amino (PEG-NH2, number average molecular weight is 1000).

[0031] Comparative Example 5 An environmentally friendly ceramic, the raw material composition and preparation method are basically the same as Example 6, the difference is that the composite binder is replaced by equal weight of the composite binder prepared by the following method: The preparation method of the composite binder is basically the same as Example 2, the difference is that the composite binder is replaced by equal weight of the polyethylene glycol modified hydroxyapatite prepared by step S3 of Example 2.

[0032] Comparative Example 6 An environmentally friendly ceramic, the raw material composition and preparation method are basically the same as Example 6, the difference is that the composite binder is replaced by equal weight of the composite binder prepared by the following method: S1: 2g of 3-aminopropyl triethoxysilane is weighed, added with 20ml of deionized water, stirred at 40℃ for 3h to obtain 3-aminopropylsilanetriol; 100g of hydroxyapatite is added into 500ml of 50wt% ethanol aqueous solution, ultrasonic dispersion for 15min to obtain a hydroxyapatite dispersion; under nitrogen protection, 3-aminopropylsilanetriol is slowly added into the hydroxyapatite dispersion, and the dropping is completed for 20min, then the temperature is increased to 90℃, and the reaction is carried out for 8h, then the temperature is cooled to room temperature, and the filter is extracted, washed with deionized water for 3 times (each time using 200ml of deionized water), vacuum dried at 60℃ for 5h, ground and crushed, and then passed through an 80 mesh sieve to obtain silane modified hydroxyapatite; S2: Under nitrogen protection, 500ml of anhydrous ethanol, 100g of silane modified hydroxyapatite and 5ml of glacial acetic acid are added into a reactor, the temperature is increased to 35℃ and stirred for 20min, then 100ml of 1wt% acetic acid aqueous solution containing 20g of oxidized chitosan is slowly added, the dropping is completed for 20min, then the temperature is increased to 65℃, and the reaction is carried out for 9h, then the temperature is decreased to room temperature, the pH is adjusted to neutral with 5wt% NaOH solution, the reaction liquid is poured into 800ml of acetone, the precipitate is stirred and separated, filtered, washed with acetone for 3 times (each time using 300ml of acetone), and then vacuum dried at 45℃ for 12h to obtain chitosan modified silane hydroxyapatite; S3: 500 ml PBS buffer (phosphate buffer) (0.1 M, pH = 8.5) was added to the reactor, 100 g of chitosan modified silane hydroxyapatite was stirred for 2 h, 2 g of borax pentahydrate was dissolved in 20 mL of 50°C deionized water, stirred until completely dissolved, slowly added to the reactor, dropwise added for 20 min, after dropping, the temperature was raised to 55°C and reacted for 4 h, 0.5 M HCl was added to adjust the pH to 7.0, then 20 ml of glycerol and 80 ml of deionized water were added and stirred to obtain a composite adhesive.

[0033] The main components of the red mud used in the examples and comparative examples of the present application are silicon dioxide (25.43 wt%), aluminum oxide (17.36 wt%), iron oxide (17.04 wt%), calcium oxide (36.46 wt%), and the particle size is uniformly distributed in 80-100 mesh; the main components of fly ash are silicon dioxide (54.9 wt%), aluminum oxide (26.4 wt%), iron oxide (11.2 wt%), calcium oxide (5.8 wt%), etc., and the particle size is uniformly distributed in 20-40 mesh; the purple sand soil is Xijin purple sand soil (sand content 69.5 wt%, calcium carbonate content 7.8 wt%); the quartz specification is 140 mesh, produced by Inner Mongolia Changfan Quartz Sand Co., Ltd.; the hydroxyapatite model is HAP07-E, produced by Nanjing Junzhu Biological Technology Co., Ltd.; the particle size of waste glass powder is 400 mesh; the particle size of spodumene is 300 mesh.

[0034] The preparation method of oxidized dextran used in Comparative Example 2 is as follows: 4 g of dextran (β-glucan, number average molecular weight 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 completely dissolve; then continue to stir in the dark at room temperature for 12 h, 1.5 mL of ethylene glycol was added to the above mixed solution, continue to stir for 3 h to terminate the reaction, then transfer into a dialysis bag (8000 Da), and dialyze in deionized water for 2 days, change water every 6 h, 2000 ml each time, freeze-dry at -40°C for 36 h to obtain oxidized dextran.

[0035] The green body prepared in step (3) and the finally prepared environment-friendly ceramic in Examples 5-7 and Comparative Examples 1-6 were tested for bending strength and apparent porosity, and the results are shown in Table 1.

[0036] Bending strength test: KZJ-30 type electric bending strength tester was used to determine the bending strength of the sample, and the calculation formula is as follows: In the formula, Bending strength ; P - the load (N) when the sample breaks; L—Supporting knife distance between the gap (mm), this experiment is 30 mm; B—Width of the sample fracture (mm); H—Height of the sample fracture (mm); K—Coefficient, K=1.

[0037] Apparent porosity test: the final preparation of clean environmental protection ceramics is put into a drying oven, dried at 110℃±5℃ to constant weight, then cooled to room temperature in a desiccator, and the dry weight (m1) of the sample is measured to 0.001g. Put the dried sample into a vacuum container, start the vacuum pump to make the residual pressure in the vacuum container less than 2500Pa, and the sample is kept under this vacuum for 15min; open the stopcock between the vacuum container and the storage bottle, start to inject distilled water, and make the distilled water rise to 20mm above the sample within 3min; continue to pump for 30min, then close the vacuum pump to restore the vacuum container to normal pressure, and keep the sample immersed under normal pressure for 30min; put the saturated sample after immersion into a basket and hang it in a container filled with distilled water with overflow pipe, weigh the suspended mass (m2) of the saturated sample in distilled water to 0.001g. According to GB / T29862, select pure cotton towels, cut the towels into squares with a side length of 14cm, soak them in distilled water for 5min, take them out and stack them into squares with a side length of 7cm, lay them under the pressure head of the press, the pressure head size should be able to completely cover the towel, and the pressure is raised to 3.3kN±0.2KN for pressure holding, and the pressure holding time is 10s, then use a clean cotton cloth to wipe and absorb the liquid discharged around the pressure head, and then take out the towel containing distilled water. Take the sample out of the distilled water, wipe the liquid attached to the surface of the sample with a towel saturated with distilled water, and weigh the mass (m3) of the saturated sample in the air within 30s to 0.001g. The basket is made of 0.2mm diameter metal wire, which is used to weigh the mass of the saturated distilled water sample. The wire is a 0.2mm diameter inelastic and clean wire. The apparent porosity is calculated by the following formula: q=(m3-m1) / (m3-m2)×100%.

[0038] Table 1 Performance index of environmental protection ceramics

[0039] As can be seen from the data of examples 5, 6 and 7 in table 1, the environmental protection ceramics prepared by the application have excellent bending strength and apparent porosity.

[0040] The composite binder added in the environment-friendly ceramic prepared by the application takes hydroxyapatite as a matrix, and introduces hydroxyl groups, dynamic reversible Schiff base bonds, borate ester bonds and mercapto groups. Unreacted hydroxyl groups on the chitosan chain in the composite binder can form strong hydrogen bonds with other ceramic particles, thereby improving the strength of the green body. The interpenetrating and winding of the long chain of polyethylene glycol effectively fills the gaps between the ceramic particles, and the flexibility and lubricity thereof reduce stress concentration during sintering and inhibit the expansion of microcracks. The dynamic Schiff base bonds in the composite binder can reversibly break and recombine during the processing of the green body, effectively dissipating stress and promoting particle rearrangement, thereby reducing local stress concentration. The borate ester bonds also have dynamic reversible characteristics, and can adjust the viscoelasticity of the bonding network by breaking and regenerating the ester bonds, thereby enhancing the deformation adaptability of the green body during the forming process. The synergistic effect of the dynamic bonds not only improves the interface bonding between the ceramic particles, but also effectively inhibits the expansion of microcracks through the energy dissipation mechanism of the reversible bonds. The mercapto groups in the composite binder undergo oxidation reaction to form disulfide bonds at high temperature, further constructing a dynamic crosslinking network, thereby improving the toughness and structural stability of the ceramic. The synergistic effect of various functional groups significantly enhances the bonding strength and stress dissipation capacity between the green body particles. At the same time, through the space steric hindrance effect and network filling effect, the particles are promoted to be uniformly dispersed and effectively fill the pores, and finally the environment-friendly ceramic with compact structure and excellent mechanical properties is formed.

[0041] In Comparative Example 4, the mercapto polyethylene glycol amino is replaced by polyethylene glycol amino, and the main reason for the decrease in the bending strength and the increase in the apparent porosity is the lack of disulfide bond crosslinking network. The polyethylene glycol amino can only participate in crosslinking through Schiff base reaction and cannot form dynamic disulfide bonds through oxidation, resulting in a significant decrease in the crosslinking density of the three-dimensional network, and finally causing the decrease in the bending strength of the ceramic.

[0042] The above is only a preferred embodiment of the application and is not intended to limit the application; however, for ordinary skilled persons in the art, some minor changes, modifications and equivalent changes of the above disclosed technical content can be made without departing from the scope of the technical solutions of the application, and all equivalent embodiments of the application are obtained; at the same time, any equivalent changes, modifications and evolution of the above embodiments according to the essential technology of the application are still within the protection scope of the technical solutions of the application.

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: Hydroxyapatite reacts with 3-aminopropyltriethoxysilane to produce silane-modified hydroxyapatite. S2: Silane-modified hydroxyapatite reacts with oxidized chitosan under the action of a catalyst to generate chitosan-modified silane hydroxyapatite. 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. S4: Polyethylene glycol-modified hydroxyapatite reacts with borax pentahydrate to form a composite binder.

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 composite flux is a mixture of spodumene and waste glass powder.

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

8. The environmentally friendly ceramic according to claim 1, characterized in that, In step S2, the catalyst is glacial acetic acid.

9. An environmentally friendly ceramic according to claim 1, characterized in that, In step S3, the catalyst is glacial acetic acid.

10. A method for preparing environmentally friendly ceramics according to any one of claims 1-9, 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.

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