High-temperature-resistant anti-burst light castable and preparation process thereof

Abstract

The invention relates to a high-temperature-resistant anti-burst lightweight castable and a preparation process thereof, and belongs to the technical field of refractory materials. The preparation method comprises the following steps: by taking 35-70 parts of lightweight aggregate, 5-25 parts of fine powder, 10-20 parts of ceramic fiber, 2-5 parts of hollow microspheres, 5-10 parts of a functional additive, 0.5-1 part of a curing agent and 5-8 parts of water as raw materials, uniformly stirring, casting and molding, and curing and baking to prepare the lightweight heat-insulating castable with the service temperature of 1350-1600 DEG C, cracking resistance, low heat conductivity coefficient and high strength.

Description

Technical Field

[0001] The invention belongs to the technical field of refractory materials and relates to a high-temperature resistant and anti-explosion lightweight castable and a preparation process thereof. Background Art

[0002] Lightweight castables are widely used in various thermal furnaces and burners. Due to the contradiction between the thermal insulation, strength and high temperature resistance of lightweight castables, the thermal conductivity is low and the volume density is less than 1.35g / cm 3 Lightweight castables are only used as insulation layers when the temperature exceeds 1350℃. Furnace linings are usually composed of a double-layer structure of high-temperature resistant heavy refractory materials and insulation layers. The double-layer structure not only increases the thickness of the lining and its own weight load, but also forms a weak bond between the two layers, which is easy to separate and damage. However, the design of a single-layer lightweight castable with low thermal conductivity and good insulation performance must improve the strength and high temperature resistance of the castable.

[0003] The present invention is to solve the above-mentioned technical problems. By fiber reinforcement and utilizing the air permeability of the fiber-built skeleton, an anti-burst function is obtained. Functional additives are used to replace the traditional lightweight thermal insulation castables using calcium silicate or calcium aluminate cement as a binder to improve the high temperature resistance and corrosion resistance of the lightweight thermal insulation castable, so that the lightweight castable of the present invention can be used for a long time at a high temperature of >1350°C, and the maximum service temperature can reach 1600°C. Summary of the invention

[0004] The high temperature resistant and anti-explosion lightweight castable of the present invention has the following raw material proportions by weight:

[0005] (1) Lightweight aggregate, 35-70 parts;

[0006] (2) fine powder, 5-25 parts;

[0007] (3) Ceramic fiber, 10-20 parts;

[0008] (4) hollow microspheres, 2 to 5 parts;

[0009] (5) functional additives, 5 to 10 parts;

[0010] (6) Curing agent, 0.1 to 1 part;

[0011] (7) Water, 5 to 8 parts.

[0012] Furthermore, the lightweight aggregate is one of alumina lightweight aggregate and porous alumina ceramic or a mixture of the two;

[0013] The lightweight aggregate comprises three particle sizes of 0.2-1 mm, 1-3 mm, and 3-5 mm, and the three particle size powders are mixed in a ratio of 1:1-3:2-5;

[0014] The fine powder is one of alumina fine powder and mullite fine powder or a mixture of the two, and its particle size is 0.074mm to 0.147mm;

[0015] The ceramic fiber is one of alumina ceramic fiber and mullite ceramic fiber or a mixture of the two, and its length is 0.1 to 20 cm;

[0016] The hollow microspheres are fused silica microspheres, and their SiO 2 Content>99wt%, microbead diameter 0.40~1.2μm;

[0017] The functional additive is a mixture of water-based organic silicone resin and alumina sol, and the functional additive ingredients meet the requirements of Al 2 O 3 :SiO 2 The molar ratio is 1.5-2.5:1;

[0018] The curing agent is triethanolamine.

[0019] The preparation method of the high temperature resistant and anti-explosion lightweight castable comprises the following steps: vigorously mixing lightweight aggregate, fine powder, ceramic fiber and hollow microspheres, adding functional additives, curing agent and water, stirring evenly again, and casting into shape.

[0020] The curing and baking method of the high temperature resistant and burst resistant lightweight castable is as follows: after curing at room temperature for 24 hours, demoulding is performed, baking is performed at 110 to 200° C. for 24 to 48 hours, and then heating is performed to the service temperature at a heating rate of ≤20° C. / h to obtain a lightweight thermal insulation castable with good anti-stripping performance, anti-burst performance, low thermal conductivity and high strength at a service temperature of 1350 to 1600° C.

[0021] The main raw material component of the present invention is alumina, which has high strength and good high temperature resistance; the alumina ceramic fiber and mullite ceramic fiber used have high strength, good erosion resistance and good wear resistance, have good fusion with the main component alumina and produce a pinning effect, so as to achieve fiber reinforcement and anti-stripping and anti-cracking effects of lightweight castables; a cement-free functional additive is used as a binder, and its main components are water-based organic silicone resin and alumina sol. The water-based organic silicone resin can act as a water reducer at room temperature, and at the same time, reacts with a curing agent to solidify and shape, and is bonded and formed after hydration with the alumina sol. After drying, an interlaced structure is formed and embedded between particles and fine powder, so as to improve the bonding strength of the lightweight castable blank; at high temperature, the organic silicone resin covering the surface of the alumina is finally converted into active amorphous silica, which reacts with the active alumina in a solid solution manner to generate mullite to promote sintering, reduce the temperature sensitivity of the castable, and make the lightweight castable of the present invention maintain stable strength at room temperature, medium temperature and high temperature, and the flexural strength in the whole temperature range exceeds 4MPa.

[0022] The beneficial effects of the present invention are mainly reflected in the following aspects:

[0023] (1) The lightweight castable of the present invention has high strength, with a compressive strength of ≥20 MPa at room temperature, and a flexural strength of ≥4.0 MPa in the full temperature range of 110°C×24h, 900°C×24h, 1350°C×24h, and 1600°C×24h, which meets the service requirements of a single-layer lining material to bear its own weight and resist the scouring and friction of hot air flow;

[0024] (2) The lightweight castable of the present invention has low thermal conductivity. At 1100°C, the thermal conductivity is ≤0.25 W·m -1 ·K -1 , at 1400℃, thermal conductivity ≤0.30W·m -1 ·K -1 , good thermal insulation effect;

[0025] (3) The lightweight castable of the present invention has good high-temperature volume stability. After heat treatment at high temperatures of 1350°C × 3h, 1450°C × 3h, and 1600°C × 3h, the linear change rate is ≤ ±0.2%;

[0026] (4) The cost of the present invention is low. Compared with the double-layer design of a heavy working layer and a light insulation layer, the weight of the single-layer lining castable of the present invention is reduced by more than 60%, the lining is thinned by more than 50%, the amount of material used is reduced, and the relative cost is reduced. DETAILED DESCRIPTION

[0027] Example 1

[0028] The high temperature resistant and anti-explosion lightweight castable of the present invention has the following raw material proportions by weight:

[0029] (1) Lightweight aggregate, 70 parts;

[0030] (2) fine powder, 5 parts;

[0031] (3) Ceramic fiber, 10 parts;

[0032] (4) hollow microspheres, 2 parts;

[0033] (5) functional additives, 5 parts;

[0034] (6) curing agent, 0.5 part;

[0035] (7) Water, 5 parts.

[0036] The lightweight aggregate is alumina lightweight aggregate, which includes three particle sizes of 0.2-1 mm, 1-3 mm, and 3-5 mm, and the three particle sizes are mixed in a ratio of 1:1:2; the fine powder is mullite fine powder, and its particle size is 0.074 mm-0.147 mm; the ceramic fiber is alumina ceramic fiber, and its length is 0.1-20 cm; the hollow microsphere is fused quartz microsphere, and its SiO 2 Content> 99wt%, microsphere diameter 0.40 ~ 1.2μm; the functional additive is a mixture of water-based silicone resin and alumina sol, and the functional additive ingredients meet the requirements of Al 2 O 3 :SiO 2 The molar ratio is 1.5:1; the curing agent is triethanolamine.

[0037] Preparation method: After vigorously mixing lightweight aggregate, fine powder, ceramic fiber and hollow microspheres, add functional additives and water, stir evenly again, and pour into shape.

[0038] Curing and baking method: demould after curing at room temperature for 24 hours, then bake at 200℃ for 24 hours, and then heat to the service temperature at a heating rate of ≤20℃ / h.

[0039] The main properties of the lightweight castable in Example 1 are: high strength, with a room temperature compressive strength of 25 MPa; its flexural strength is stable in the entire temperature range, all exceeding 4.0 MPa, 4.8 MPa at 110°C × 24h, 4.2 MPa at 900°C × 24h, 4.6 MPa at 1350°C × 24h, and ≥ 4.2 MPa at 1600°C × 24h; its thermal conductivity is also low, with good thermal insulation effect, and the thermal conductivity is 0.22 W·m at 1100°C -1 ·K -1 , thermal conductivity 0.28W·m at 1400℃ -1 ·K -1 Its re-burning phase change rate is very low, and its high-temperature volume stability is good. The linear change rate after heat treatment at 1350℃×3h is -0.10%, after heat treatment at 1450℃×3h is -0.13%, and after heat treatment at 1600℃×3h is -0.18%, which can meet the service environment of 1600℃.

[0040] Example 2

[0041] The high temperature resistant and anti-explosion lightweight castable of the present invention has the following raw material proportions by weight:

[0042] (1) Lightweight aggregate, 35 parts;

[0043] (2) fine powder, 25 parts;

[0044] (3) Ceramic fiber, 20 parts;

[0045] (4) hollow microspheres, 5 parts;

[0046] (5) functional additives, 10 parts;

[0047] (6) Curing agent, 1 part;

[0048] (7) Water, 8 parts.

[0049] The lightweight aggregate is porous alumina ceramic; it includes three particle sizes of 0.2-1 mm, 1-3 mm, and 3-5 mm, and the three particle sizes are mixed in a ratio of 1:3:5; the fine powder is alumina fine powder, and its particle size is 0.074 mm-0.147 mm; the ceramic fiber is a mixture of alumina ceramic fiber and mullite ceramic fiber in a ratio of 1:1, and the fiber length is 0.1-20 cm; the hollow microspheres are fused quartz microspheres, SiO 2 Content> 99wt%, microsphere diameter 0.40 ~ 1.2μm; the functional additive is a mixture of water-based silicone resin and alumina sol, and the functional additive ingredients meet the requirements of Al 2 O 3 :SiO 2 The molar ratio is 2.5:1; the curing agent is triethanolamine.

[0050] Preparation method: After vigorously mixing lightweight aggregate, fine powder, ceramic fiber and hollow microspheres, add functional additives and water, stir evenly again, and pour into shape.

[0051] Curing and baking method: demould after curing at room temperature for 48 hours, then bake at 160℃ for 48 hours, and then heat to the service temperature at a heating rate of ≤20℃ / h.

[0052] The main properties of the lightweight castable in Example 2 are: high strength, with a room temperature compressive strength of 23 MPa; its flexural strength is stable in the entire temperature range, all exceeding 4.0 MPa, 4.6 MPa at 110°C × 24h, 4.1 MPa at 900°C × 24h, 4.4 MPa at 1350°C × 24h, and ≥ 4.1 MPa at 1600°C × 24h; its thermal conductivity is also low, with good thermal insulation effect, and the thermal conductivity is 0.21 W·m at 1100°C -1 ·K -1 , thermal conductivity 0.26W·m at 1400℃ -1 ·K -1Its re-burning phase change rate is very low, and its high-temperature volume stability is good. The linear change rate after heat treatment at 1350℃×3h is -0.11%, after heat treatment at 1450℃×3h is -0.14%, and after heat treatment at 1600℃×3h is -0.20%, which can meet the service environment of 1600℃.

[0053] Example 3

[0054] The high temperature resistant and anti-explosion lightweight castable of the present invention has the following raw material proportions by weight:

[0055] (1) Lightweight aggregate, 50 parts;

[0056] (2) fine powder, 15 parts;

[0057] (3) Ceramic fiber, 15 parts;

[0058] (4) hollow microspheres, 4 parts;

[0059] (5) functional additives, 8 parts;

[0060] (6) curing agent, 0.8 part;

[0061] (7) Water, 7 parts.

[0062] The lightweight aggregate is a mixture of alumina lightweight aggregate and porous alumina ceramic in a ratio of 1:1; it contains three particle sizes of 0.2-1 mm, 1-3 mm, and 3-5 mm, and the three particle sizes are mixed in a ratio of 1:2:4; the fine powder is a mixture of alumina fine powder and mullite fine powder in a ratio of 1:1, and its particle size is 0.074 mm to 0.147 mm; the ceramic fiber is mullite ceramic fiber, and its length is 0.1 to 20 cm; the hollow microspheres are fused quartz microspheres, SiO 2 Content> 99wt%, microsphere diameter 0.40 ~ 1.2μm; the functional additive is a mixture of water-based silicone resin and alumina sol, and the functional additive ingredients meet the requirements of Al 2 O 3 :SiO 2 The molar ratio is 2:1; the curing agent is triethanolamine.

[0063] Preparation method: After vigorously mixing lightweight aggregate, fine powder, ceramic fiber and hollow microspheres, add functional additives and water, stir evenly again, and pour into shape.

[0064] Curing and baking method: demould after curing at room temperature for 48 hours, then bake at 200℃ for 24 hours, and then heat to the service temperature at a heating rate of ≤20℃ / h.

[0065] The main properties of the lightweight castable in Example 3 are: high strength, with a room temperature compressive strength of 23 MPa; its flexural strength is stable in the entire temperature range, all exceeding 4.0 MPa, 4.7 MPa at 110°C × 24h, 4.2 MPa at 900°C × 24h, 4.5 MPa at 1350°C × 24h, and ≥ 4.2 MPa at 1600°C × 24h; its thermal conductivity is also low, with good thermal insulation effect, and the thermal conductivity is 0.22 W·m at 1100°C -1 ·K -1 , thermal conductivity 0.28W·m at 1400℃ -1 ·K -1 Its re-burning phase change rate is very low, and its high-temperature volume stability is good. The linear change rate after heat treatment at 1350℃×3h is -0.11%, after heat treatment at 1450℃×3h is -0.13%, and after heat treatment at 1600℃×3h is -0.19%, which can meet the service environment of 1600℃.

[0066] Comparative Example 1

[0067] A lightweight castable, wherein the functional additive and curing agent in Example 1 are replaced with calcium aluminate cement, the other components remain unchanged, the addition amount of calcium aluminate cement is 5.5 parts by weight, and the preparation method and curing method are the same as those in Example 1. The properties of the prepared castable are shown in Table 1. At 1300°C, obvious linear shrinkage begins to occur, the shrinkage rate becomes significantly larger, and structural collapse occurs at 1600°C, and the performance is lost. It can be seen that the use of calcium aluminate cement as a curing binder cannot meet the high strength problem under high temperature conditions.

[0068] Comparative Example 2

[0069] A lightweight castable, wherein the functional additive and curing agent in Example 1 are replaced by alumina sol, the other components remain unchanged, the addition amount of alumina sol is 5.5 parts by weight, and the preparation method and curing method are the same as those in Example 1. The properties of the prepared castable are shown in Table 1, and it can be seen that under the medium temperature condition of 900°C, the flexural strength decreases significantly, and in the high temperature range from 1350°C to 1600°C, the flexural strength begins to rise, but there is still a large gap compared with Example 1. The reduction in flexural strength under such medium temperature conditions may have an adverse effect on the structural stability of the castable. Therefore, the use of alumina sol alone as a curing binder has the problem of low medium temperature strength, and at the same time, it also causes the need for a higher sintering temperature.

[0070] Table 1 List of measured properties of the present invention

[0071]

[0072]

Claims

1. A high temperature resistant and anti-explosion lightweight castable, characterized in that: By weight, 35-70 parts of lightweight aggregate, 5-25 parts of fine powder, 10-20 parts of ceramic fiber, and 2-5 parts of hollow microspheres are vigorously mixed evenly, and then 5-10 parts of functional additives, 0.1-1 parts of curing agent and 5-8 parts of water are added. Stir evenly again and pour into shape; after curing at room temperature for 24-48 hours, demould, bake at 110-200℃ for 24-48 hours, and then heat to the service temperature at a heating rate of ≤20℃ / h.

2. The casting material according to claim 1, characterized in that The lightweight aggregate is alumina lightweight aggregate, porous alumina ceramic or a mixture of the two.

3. The casting material according to claim 1, characterized in that The lightweight aggregate comprises three particle sizes of 0.2-1 mm, 1-3 mm, and 3-5 mm, and the three particle size powders are mixed in a ratio of 1:1-3:2-5.

4. The casting material according to claim 1, characterized in that The fine powder is one of alumina fine powder and mullite fine powder or a mixture of the two, and its particle size is 0.074mm-0.147mm.

5. The casting material according to claim 1, characterized in that The ceramic fiber is one of alumina ceramic fiber and mullite ceramic fiber or a mixture of the two, and the length thereof is 0.1-20 cm.

6. The casting material according to claim 1, characterized in that The hollow microspheres are fused silica microspheres, with SiO2 content greater than 99 wt% and a microsphere diameter of 0.40 to 1.2 μm.

7. The casting material according to claim 1, characterized in that The functional additive is a mixture of water-based organic silicon resin and alumina sol, and the functional additive ingredients satisfy the molar ratio of Al2O3:SiO2 of 1.5-2.5:

1.

8. The casting material according to claim 1, characterized in that The curing agent is triethanolamine.

9. A high temperature resistant and anti-explosion lightweight castable as claimed in any one of claims 1 to 8.

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