Preparation method of high-temperature sintered colored sand

Abstract

The invention provides a preparation method of high-temperature sintered colored sand, and relates to raw material pretreatment, mixing and granulation, high-temperature sintering and post-treatment strengthening. The high-purity quartz sand is adopted, and the color development stability is improved through an optimized coloring system and an optimized fluxing agent ratio. A high-temperature sintering process is combined with nitrogen protection, so that the metal oxide forms a stable spinel structure, and the weather resistance and the mechanical strength are improved. The gradient cooling technology reduces microcracks and improves the wear resistance of the colored sand. A hydrophobic coating is formed by adopting a sol-gel method in post-treatment, and a CrN film is deposited through magnetron sputtering, so that the wear resistance is improved. The colored sand disclosed by the invention has excellent coloring stability, wear resistance and weather resistance, and can be widely applied to the fields of building decoration, industrial terraces and artistic coatings.

Description

Technical Field

[0001] The present invention relates to a preparation method of high-temperature sintered colored sand. Background Art

[0002] Colored sand is a material widely used in architectural decoration, industrial floor coatings, and artistic coatings. Its coloring stability, weather resistance, and abrasion resistance are important indicators to measure its quality. Traditional colored sand preparation methods mainly include dyeing methods and low-temperature sintering methods, but these methods have problems such as uneven coloring, poor weather resistance, and easy fading. In addition, some colored sand may undergo color change or quality deterioration in high-temperature environments, limiting its application in special environments. Therefore, developing a preparation method of high-temperature sintered colored sand to improve its coloring stability, abrasion resistance, and environmental adaptability has become the focus of current research. Summary of the Invention

[0003] The purpose of the present invention is to solve the above deficiencies of the prior art and provide a preparation method of high-temperature sintered colored sand.

[0004] A preparation method of high-temperature sintered colored sand includes the following steps:

[0005] S1: Pretreatment of raw materials;

[0006] Select high-purity quartz sand to avoid interference of impurity ions on sintering color development; classify the quartz sand into three grades by vibrating screening, where the coarse sand has a particle size of 1.5 - 2.0 mm, the medium sand has a particle size of 0.5 - 1.5 mm, and the fine sand has a particle size of 0.1 - 0.5 mm; soak in 5% dilute hydrochloric acid by mass fraction for 30 min in sequence to remove metal oxides, rinse with deionized water until neutral, and dry at 120°C for 2 h;

[0007] Use inorganic metal oxides as colorants to color the quartz sand. The flux is compounded with borax and sodium carbonate at a mass fraction ratio of 3:1 to reduce the melting point of the glaze layer to below 800°C. The clay is selected as kaolin calcined at 600°C for 2 h to remove hydroxyl groups to avoid sintering bubble defects;

[0008] S2: Mixing and granulation;

[0009] Put the colorant and quartz sand into the granulation equipment at a mixing ratio of 1:8 by mass, and spray and add sodium silicate diluted to a mass fraction concentration of 10% as an adhesive, with a dosage of 4% of the total mass. The granulation equipment uses a high-speed centrifugal coating machine to make the colorant evenly adhere to the surface of the sand grains through centrifugal force to form a continuous glaze layer;

[0010] Then use a fluidized bed for drying, with a drying temperature of 80°C, a wind speed of 2 m / s, the moisture content at the end of drying ≤ 0.5%, and the surface roughness Ra of the dried particles < 1 μm;

[0011] S3: High-temperature sintering;

[0012] Preheating stage: Completely remove the residual moisture and organic volatiles from the colored sand;

[0013] Main sintering stage: Melt the flux to form a glass phase, and metal oxide ions diffuse into the glaze layer;

[0014] High-temperature color fixation stage: Promote the bonding of Fe 3+ , Co 2+ plasma with the SiO2 lattice to form a stable spinel structure;

[0015] Atmosphere control: Introduce nitrogen for protection to prevent the reduction and discoloration of metal oxides;

[0016] Use a gradient cooling process to cool the colored sand;

[0017] First stage: Avoid the explosion of the glass phase;

[0018] Second stage: Control the stress of crystal form transformation;

[0019] Third stage: Prevent microcracks caused by rapid cooling;

[0020] S4: Post-treatment strengthening

[0021] Adopt the sol-gel method to spray an ethanol dispersion liquid to form a hydrophobic coating on the surface of the colored sand, and form a porous hydrophobic film after drying;

[0022] Magnetron sputtering deposit a CrN film on the surface of the hydrophobic coating to perform wear resistance treatment on the colored sand;

[0023] Grade the colored sand through a three-stage ultrasonic vibrating screen to remove sintered and adhered particles.

[0024] As a further improvement, the mass fraction of SiO2 in the high-purity quartz sand described in S1

[0025] ≥99.2%, and the impurity ions interfering with color formation include Fe 3+ , Ca 2+ .

[0026] As a further improvement, the coarse sand described in S1 is used as floor aggregate, the medium sand is used as conventional decorative sand, and the fine sand is used as artistic paint.

[0027] As a further improvement, the colorants described in S1 include red series and blue series. Among them, the red series colorant adopts a mixture of Fe2O3 with a mass fraction of 60-70% and MnO2 with a mass fraction of 5-10%, and the blue series colorant adopts a mixture of Co3O4 with a mass fraction of 50% and Al2O3 with a mass fraction of 20%.

[0028] As a further improvement, the temperatures of each stage in the high-temperature sintering described in S3 are as follows:

[0029] Preheating stage: 300°C → 500°C, heating rate 5°C / min, holding for 30 min;

[0030] Main sintering stage: 800°C → 1000°C, heating rate 8°C / min, holding for 1.5 h;

[0031] High-temperature color fixation stage: 1200°C → 1300°C, heating rate 3°C / min, holding for 30 min.

[0032] As a further improvement, the temperatures of each stage in the gradient cooling process described in S3 are as follows:

[0033] First stage: 1300°C → 800°C, rate 10°C / min;

[0034] Second stage: 800°C → 400°C, rate 5°C / min;

[0035] Third stage: 400°C → room temperature, natural cooling.

[0036] Beneficial effects:

[0037] Selection of high-purity raw materials: High-purity quartz sand with SiO2 content ≥ 99.2% is used, effectively reducing the interference of impurity ions such as Fe 3+ and Ca 2+ on color development, improving the color purity and stability of the colored sand.

[0038] Optimized coloring system: Inorganic metal oxides are selected as colorants, and a flux is combined to reduce the melting point of the glaze layer, making the metal oxides diffuse more evenly and improving the color development effect of the colored sand.

[0039] Advanced sintering process: Through staged high-temperature sintering up to 1300°C and combined with a nitrogen protection environment, the color of the colored sand is made more stable, and a stable spinel structure is formed, improving the weather resistance.

[0040] Gradient cooling technology: Avoids microcracks caused by rapid cooling, improving the mechanical strength and wear resistance of the colored sand.

[0041] Post-treatment strengthening: A hydrophobic coating is formed by the sol-gel method and combined with magnetron sputtering deposition of CrN film to improve the wear resistance, waterproofness and chemical corrosion resistance of the colored sand.

[0042] Fine screening technology: Adhesion particles are effectively removed through a three-stage ultrasonic vibrating screen, improving the product uniformity and quality stability. Description of the drawings

[0043] Figure 1 It is a flow chart of a preparation method of high-temperature sintered colored sand. Specific implementation mode

[0044] To deepen the understanding of the present invention, the present invention will be further described in detail below in conjunction with embodiments and drawings. The embodiments are only used to explain the present invention and do not constitute a limitation on the protection scope of the present invention.

[0045] As Figure 1 shown, a preparation method of high-temperature sintered colored sand includes the following steps:

[0046] 1. Raw material pretreatment

[0047] (1) Substrate selection and treatment

[0048] Substrate type: High-purity quartz sand is selected, and the mass fraction content of SiO2 ≥ 99.2%, avoiding impurity ions such as Fe 3+ , Ca 2+ , interfering with sintering and color development;

[0049] Particle size grading: The quartz sand is divided into three grades by vibrating screening:

[0050] Coarse sand: 1.5 - 2.0 mm, used for floor aggregate;

[0051] Medium sand: 0.5 - 1.5 mm, conventional decorative sand;

[0052] Fine sand: 0.1 - 0.5 mm, used for artistic coatings;

[0053] Cleaning process: Soak in 5% dilute hydrochloric acid for 30 min in sequence to remove metal oxides → rinse with deionized water until neutral → dry at 120 °C for 2 h.

[0054] (2) Colorant formula design

[0055] Inorganic metal oxides:

[0056] Red series: Mix Fe2O3 with a mass fraction of 60 - 70% and MnO2 with a mass fraction of 5 - 10% to enhance the red color saturation;

[0057] Blue series: Compound Co3O4 with a mass fraction of 50% and Al2O3 with a mass fraction of 20% to enhance the high-temperature stability;

[0058] Flux optimization: Borax (Na2B4O7·10H2O) and sodium carbonate (Na2CO3) are compounded according to a mass ratio of 3:1 to reduce the melting point of the glaze layer to below 800 °C;

[0059] Clay selection: Kaolin (Al2O3·2SiO2·2H2O) needs to be calcined at 600℃ for 2h to remove hydroxyl groups and avoid sintering bubble defects.

[0060] 2. Mixing and granulation

[0061] (1) Wet coating process

[0062] Mixing ratio: colorant to quartz sand mass ratio 1:8, optimal color thickness 50-80μm;

[0063] Binder selection: water glass, modulus 2.8-3.2, diluted to 10% concentration and sprayed, the amount is 4% of the total mass;

[0064] Granulation equipment: Use a high-speed centrifugal coating machine with a rotation speed of 800-1200rpm. The centrifugal force makes the colorant evenly adhere to the surface of the sand particles to form a continuous glaze layer.

[0065] (2) Drying control

[0066] Fluidized bed drying: temperature 80°C, wind speed 2m / s, moisture at drying end point ≤0.5%;

[0067] The surface roughness of the particles after drying was Ra<1μm, which was detected by laser confocal microscopy.

[0068] 3. High temperature sintering process

[0069] (1) Segmented sintering parameters

[0070] Preheating stage: 300℃→500℃, heating rate 5℃ / min, heat preservation for 30min, completely remove residual moisture and volatile organic matter;

[0071] Main sintering stage: 800℃→1000℃, heating rate 8℃ / min, holding temperature for 1.5h, flux melts to form glass phase, and metal oxide ions diffuse into the glaze layer;

[0072] High temperature fixation stage: 1200℃→1300℃, heating rate 3℃ / min, heat preservation 30min, promote Fe 3+ 、Co 2+ The plasma bonds with the SiO2 lattice to form a stable spinel structure;

[0073] Atmosphere control: nitrogen is introduced for protection, and the oxygen content is less than 3% to prevent metal oxides from reducing and discoloring, such as Fe2O3 → FeO turning black.

[0074] (2) Gradient cooling process

[0075] The first stage: 1300℃→800℃, rate 10℃ / min, to avoid glass phase cracking;

[0076] The second stage: from 800 °C to 400 °C, at a rate of 5 °C / min, controlling the crystal form transformation stress;

[0077] The third stage: from 400 °C to room temperature, natural cooling, preventing microcracks caused by rapid cooling.

[0078] 4. Post-treatment strengthening

[0079] (1) Surface modification

[0080] Hydrophobic coating: Spraying a nano-SiO2 ethanol dispersion with a particle size of 20 - 50 nm by the sol-gel method, and forming a porous hydrophobic film after drying, with a contact angle ≥ 120°;

[0081] Wear-resistant treatment: Magnetron sputtering deposition of a CrN film with a thickness of 200 nm on the surface of the hydrophobic coating, with a hardness of HV1800.

[0082] (2) Finished product screening

[0083] Through a three-stage ultrasonic vibrating screen, grading with a pore size error of ±0.05 mm, and removing sintered and adhered particles.

[0084] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing high-temperature sintered colored sand, characterized in that: The following steps are involved: S1: Raw material pretreatment; Use high-purity quartz sand to avoid impurity ions interfering with sintering color development; divide the quartz sand into three levels by vibration screening, among which the coarse sand particle size is 1.5-2.0mm, the medium sand particle size is 0.5-1.5mm, and the fine sand particle size is 0.1-0.5mm; soak in 5% dilute hydrochloric acid for 30 minutes to remove metal oxides, rinse with deionized water until neutral, and dry at 120℃ for 2 hours; Inorganic metal oxides are used as colorants to color quartz sand. Borax and sodium carbonate are mixed in a mass ratio of 3:1 as flux to reduce the melting point of the glaze layer to below 800°C. Kaolin calcined at 600°C for 2h to remove hydroxyl groups is used as clay to avoid sintering bubble defects. S2: Mixing and granulation; The colorant and quartz sand are mixed in a mass ratio of 1:8 and added into the granulation equipment, and water glass is diluted to a concentration of 10% by mass and added as a binder by spraying, and the amount used is 4% of the total mass. The granulation equipment uses a high-speed centrifugal coating machine to make the colorant evenly adhere to the surface of the sand particles through centrifugal force to form a continuous glaze layer; Afterwards, the fluidized bed was used for drying, with a drying temperature of 80°C, a wind speed of 2m / s, a moisture content of ≤0.5% at the drying end point, and a surface roughness of the particles after drying of Ra <1μm; S3: high temperature sintering; Preheating stage: to completely remove residual moisture and volatile organic matter from the colored sand; Main sintering stage: melting the flux to form a glass phase and diffusing metal oxide ions into the glaze layer; High temperature fixation stage: promote Fe 3+ 、Co 2+ The plasma bonds with the SiO2 lattice to form a stable spinel structure; Atmosphere control: nitrogen protection is introduced to prevent metal oxides from reducing and discoloring; Use gradient cooling process to cool the colored sand; The first stage: avoid glass phase explosion; The second stage: controlling the crystal transformation stress; The third stage: prevent micro cracks caused by sudden cooling; S4: Post-processing enhancement The sol-gel method is used to spray ethanol dispersion to form a hydrophobic coating on the surface of the colored sand, and a porous hydrophobic film is formed after drying; CrN film was deposited on the surface of the hydrophobic coating by magnetron sputtering to make the colored sand wear-resistant; The colored sand is graded through a three-stage ultrasonic vibration screen to remove sintered and adhered particles.

2. The method for preparing high-temperature sintered colored sand according to claim 1, characterized in that: The mass fraction of SiO2 in the high-purity quartz sand described in S1 is ≥99.2%, and the impurity ions that interfere with color formation include Fe 3+ , Ca 2+ .

3. The method for preparing high temperature sintered colored sand according to claim 1, characterized in that: The coarse sand described in S1 is used for floor aggregate, the medium sand is used for conventional decorative sand, and the fine sand is used for artistic coatings.

4. The method for preparing high-temperature sintered colored sand according to claim 1, characterized in that: The colorants described in S1 include red and blue colors, wherein the red colorant is a mixture of 60-70% Fe2O3 and 5-10% MnO2 by mass, and the blue colorant is a mixture of 50% Co3O4 and 20% Al2O3 by mass.

5. The method for preparing high temperature sintered colored sand according to claim 1, characterized in that: The temperatures of each stage of high temperature sintering described in S3 are: Preheating stage: 300℃→500℃, heating rate 5℃ / min, keeping warm for 30min; Main sintering stage: 800℃→1000℃, heating rate 8℃ / min, holding time 1.5h; High temperature fixing stage: 1200℃→1300℃, heating rate 3℃ / min, keeping warm for 30min.

6. The method for preparing high temperature sintered colored sand according to claim 1, characterized in that: The temperatures at each stage of the gradient cooling process described in S3 are: The first stage: 1300℃→800℃, rate 10℃ / min; The second stage: 800℃→400℃, rate 5℃ / min; The third stage: 400℃→room temperature, natural cooling.

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