CN108285350A - A kind of tri compound SiC based refractories and preparation method thereof - Google Patents

Abstract

The invention discloses a ternary composite silicon carbide refractory material, which comprises a base material and a binder. The base material is composed of 30-40 wt% silicon carbide aggregate, 10-55 wt% silicate minerals, 5-35wt% of the base material, 10-35wt% of the cordierite, and the amount of the binder is 6-12wt% of the base material. In addition, a preparation method of the above-mentioned ternary composite silicon carbide refractory material is also disclosed. The present invention introduces a high-strength, low-expansion mullite-cordierite matrix between silicon carbide aggregate particles as a binding phase by in-situ synthesis, which effectively solves the problem that artificially synthesized powder and aggregate are difficult to mix evenly in the prior art. The problem of difficult combination avoids the resulting technical defects such as low strength and poor thermal shock resistance, and significantly improves the quality of silicon carbide refractories. The invention has a simple process, not only reduces the firing temperature, but also greatly reduces the manufacturing cost, has broad market prospects, and is conducive to promoting the progress of industrial technology and application development.

Description

A kind of ternary composite silicon carbide refractory material and preparation method thereof

technical field

The invention relates to the technical field of refractory materials, in particular to a ternary composite silicon carbide refractory material and a preparation method thereof.

Background technique

Refractory materials are widely used in metallurgy, cement, glass, ceramics and other industries, and their quality is directly related to the quality and production cost of fired products. Due to long-term use at high temperatures, refractory materials need to have high strength, low thermal expansion, high fire resistance, high creep resistance and other properties, as well as good thermal and chemical stability. Silicon carbide is widely used as a refractory material due to its high temperature strength, high load softening temperature, good thermal stability and thermal conductivity.

The material system of existing silicon carbide refractories is mainly clay-silicon carbide, mullite-silicon carbide, etc., that is, silicon carbide is used as aggregate, clay, mullite fine powder, alumina (or aluminum hydroxide) Oxide materials such as fine powder and silica fine powder are used as the matrix. However, the material systems in the prior art generally have shortcomings such as low strength and high thermal expansion coefficient (the flexural strength is usually lower than 60MPa, and the thermal expansion coefficient is usually higher than 4.7×10 ^-6 ·°C ^-1 ), the main reasons are:

(1) Most of the raw materials used in the prior art (such as mullite, corundum, etc.) are mainly artificially synthesized, and the silicon carbide aggregate is a mixture of two solid phases, which is not only difficult to mix evenly, but also The combination of the two belongs to physical contact, and it is difficult to produce chemical bonding, so it is easy to cause shortcomings such as unstable product quality and low strength, making it difficult to improve the quality of silicon carbide refractories.

(2) The thermal expansion coefficient of mullite and corundum is high (the thermal expansion coefficient of the former is 5.3×10 ^-6 ·℃ ^-1 , and the latter is 8.8×10 ^-6 ·℃ ^-1 ), which leads to the The coefficient of thermal expansion is usually high and the thermal shock resistance is poor.

Since the strength and thermal expansion coefficient are the key factors that directly affect the thermal shock resistance of materials, it is urgent to research and develop a high-strength, low-expansion silicon carbide refractory material to meet the needs of industry technology and application development.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies of the prior art and provide a ternary composite silicon carbide refractory material to effectively improve the strength and thermal shock resistance of the material, thereby greatly improving product quality and reducing production costs. To meet the needs of industry technology and application development. Another object of the present invention is to provide a method for preparing the above-mentioned ternary composite silicon carbide refractory material.

The purpose of the present invention is achieved through the following technical solutions:

A ternary composite silicon carbide refractory material provided by the invention includes a base material and a binder. The base material is composed of 30-40 wt% of silicon carbide aggregate, 10-55 wt% of silicate mineral, The raw material is 5-35wt%, and the cordierite is 10-35wt%.

Further, the silicate minerals described in the present invention are andalusite, sillimanite, kyanite, or bauxite; the industrial-grade aluminum raw materials are α-Al ₂ O ₃ , γ-Al ₂ O ₃ , or Al(OH) ₃ .

In the above scheme, the silicon carbide aggregate of the present invention has a particle size of 60 to 325 meshes, the silicate minerals has a particle size of 180 to 250 meshes, the industrial grade aluminum raw material has a particle size of 180 to 250 meshes, and the cordierite has a particle size of 250-325 mesh. The binding agent is a PVA solution with a concentration of 5wt%.

Another object of the present invention is achieved through the following technical solutions:

The preparation method of the above-mentioned ternary composite silicon carbide refractory material provided by the present invention is as follows: after mixing the base materials, adding a binder and mixing them uniformly; A cordierite-mullite-silicon carbide refractory material is prepared.

The present invention introduces high-strength mullite into the silicon carbide aggregate through in-situ synthesis through the formulation system (the mullite binding phase is obtained by high-temperature in-situ synthesis of a blend of silicate minerals and industrial-grade aluminum raw materials. ), and low-expansion cordierite was added as a binding phase. The way of combination is to use the liquid phase generated during the firing process of the raw material blend, which has good wettability with the slightly oxidized silicon carbide aggregate, so that it can evenly adhere to the surface of the silicon carbide aggregate particles. While the liquid phase bonds the silicon carbide aggregate particles together, mullite is precipitated in situ from the middle, thus introducing a high-strength, low-expansion silicate phase between the silicon carbide aggregate particles as a binding phase to obtain a ternary Composite cordierite-mullite-silicon carbide refractory material.

Further, the moisture content of the dried green body in the preparation method of the present invention is less than 0.5%.

In the above solution, the sintering temperature of the preparation method of the present invention is 1300-1400° C., and the sintering time is 1-2 hours.

The present invention has the following beneficial effects:

(1) The present invention introduces mullite by in-situ synthesis, which can be evenly distributed on the particle surface of silicon carbide aggregate together with cordierite, and produces chemical bonding, thereby realizing the introduction of high-strength silicon carbide aggregate particles. , low-expansion silicate phase as the binding phase, which effectively solves the problem that the artificially synthesized powder and aggregate in the prior art are difficult to mix evenly and is difficult to combine, avoids the technical defects such as low strength caused by it, and significantly improves the The quality of silicon carbide refractories. At the same time, by introducing cordierite with low thermal expansion, the thermal expansion coefficient of the refractory material can be greatly reduced, which is beneficial to weaken the thermal stress generated inside the material during the rapid cooling and rapid heating process, thereby helping to improve the thermal shock resistance of the product. The main performance indicators of the ternary composite silicon carbide refractory material of the present invention are: flexural strength 80-100 MPa, thermal expansion coefficient 3.8-4.0×10 ^-6 ·°C ^-1 .

(2) The process of the present invention is simple, not only reduces the firing temperature, but also greatly reduces the manufacturing cost, has broad market prospects, and is conducive to promoting the progress of industrial technology and application development.

Description of drawings

The present invention will be described in further detail below in conjunction with embodiment and accompanying drawing:

Fig. 1 is the microstructure (scanning electron microscope secondary electron image) of the cordierite-mullite-silicon carbide refractory material prepared in the embodiment of the present invention.

Detailed ways

Embodiment one:

1. A ternary composite silicon carbide refractory material in this embodiment includes a base material and a binder. The base material is composed of silicon carbide aggregate (80-325 mesh) 30wt%, andalusite (180 mesh) 30wt%, α-Al ₂ O ₃ (325 mesh) 20wt%, cordierite (325mesh) 20wt%, the binder is a PVA solution with a concentration of 5wt%, and its dosage is 8wt% of the base material.

2. In this embodiment, a corundum-silicon carbide composite ceramic material using natural minerals as raw materials is as follows:

After mixing the above-mentioned base materials, add a binder and mix them evenly; after stirring and trapping the materials, select an appropriate pressure according to the size of the product for compression molding, and dry at a temperature of 110°C to obtain a green body (moisture content in the kiln <0.5%); then Firing at 1300°C for 1 hour, the cordierite-mullite-silicon carbide refractory material is obtained.

Embodiment two:

1. In this embodiment, a ternary composite silicon carbide refractory material includes a base material and a binder. The base material is composed of silicon carbide aggregate (60-325 mesh) 35wt%, sillimanite (180 mesh) 40wt% , γ-Al ₂ O ₃ (325 mesh) 15wt%, cordierite (325 mesh) 10wt%, the binder is a PVA solution with a concentration of 5wt%, and its dosage is 10wt% of the base material.

2. In this embodiment, a corundum-silicon carbide composite ceramic material using natural minerals as raw materials is as follows:

After mixing the above-mentioned base materials, add a binder and mix them evenly; after stirring and trapping the materials, select an appropriate pressure according to the size of the product for compression molding, and dry at a temperature of 110°C to obtain a green body (moisture content in the kiln <0.5%); then Firing at 1400°C for 1 hour, the cordierite-mullite-silicon carbide refractory material is obtained.

Embodiment three:

1. In this embodiment, a ternary composite silicon carbide refractory material includes a base material and a binder. The base material is composed of silicon carbide aggregate (60-325 mesh) 30wt%, kyanite (180 mesh) 25wt% , Al(OH) ₃ (325 mesh) 30wt%, cordierite (325 mesh) 15wt%, the binding agent is a PVA solution with a concentration of 5wt%, and its consumption is 6wt% of the base material.

2. In this embodiment, a corundum-silicon carbide composite ceramic material using natural minerals as raw materials is as follows:

After mixing the above-mentioned base materials, add a binder and mix them evenly; after stirring and trapping the materials, select an appropriate pressure according to the size of the product for compression molding, and dry at a temperature of 110°C to obtain a green body (moisture content in the kiln <0.5%); then Fire at 1340°C for 2 hours to obtain a cordierite-mullite-silicon carbide refractory material.

Embodiment four:

1. A ternary composite silicon carbide refractory material in this embodiment includes a base material and a binder. The base material is composed of silicon carbide aggregate (60-325 mesh) 40wt%, andalusite (180 mesh) 25wt%, α-Al ₂ O ₃ (325 mesh) 15wt%, cordierite (325 mesh) 20wt%, the binder is a PVA solution with a concentration of 5wt%, and its dosage is 6wt% of the base material.

2. In this embodiment, a corundum-silicon carbide composite ceramic material using natural minerals as raw materials is as follows:

After mixing the above-mentioned base materials, add a binder and mix them evenly; after stirring and trapping the materials, select an appropriate pressure according to the size of the product for compression molding, and dry at a temperature of 110°C to obtain a green body (moisture content in the kiln <0.5%); then Firing at 1380°C for 2 hours, the cordierite-mullite-silicon carbide refractory material is obtained.

Embodiment five:

1. In this embodiment, a ternary composite silicon carbide refractory material includes a base material and a binder. The base material is composed of silicon carbide aggregate (60-325 mesh) 40wt%, kyanite (180 mesh) 20wt% , γ-Al ₂ O ₃ (325 mesh) 28wt%, cordierite (325 mesh) 12wt%, the binder is a PVA solution with a concentration of 5wt%, and its dosage is 8wt% of the base material.

2. In this embodiment, a corundum-silicon carbide composite ceramic material using natural minerals as raw materials is as follows:

After mixing the above-mentioned base materials, add a binder and mix them evenly; after stirring and trapping the materials, select an appropriate pressure according to the size of the product for compression molding, and dry at a temperature of 110°C to obtain a green body (moisture content in the kiln <0.5%); then Firing at 1360°C for 1 hour, the cordierite-mullite-silicon carbide refractory material is obtained.

Embodiment six:

1. In this embodiment, a ternary composite silicon carbide refractory material includes a base material and a binder. The base material is composed of silicon carbide aggregate (60-325 mesh) 35wt%, bauxite (180 mesh) 50wt% , γ-Al ₂ O ₃ (250 mesh) 5wt%, cordierite (325 mesh) 10wt%, the binder is a PVA solution with a concentration of 5wt%, and its dosage is 7wt% of the base material.

2. In this embodiment, a corundum-silicon carbide composite ceramic material using natural minerals as raw materials is as follows:

After mixing the above-mentioned base materials, add a binder and mix them evenly; after stirring and trapping the materials, select an appropriate pressure according to the size of the product for compression molding, and dry at a temperature of 110°C to obtain a green body (moisture content in the kiln <0.5%); then Firing at 1340°C for 2 hours, the cordierite-mullite-silicon carbide refractory material is obtained.

Embodiment seven:

1. In this embodiment, a ternary composite silicon carbide refractory material includes a base material and a binder. The base material is composed of silicon carbide aggregate (60-325 mesh) 40wt%, sillimanite (180 mesh) 10wt% , α-Al ₂ O ₃ (325 mesh) 15wt%, cordierite (325 mesh) 35wt%, the binder is a PVA solution with a concentration of 5wt%, and its dosage is 6wt% of the base material.

2. In this embodiment, a corundum-silicon carbide composite ceramic material using natural minerals as raw materials is as follows:

After mixing the above-mentioned base materials, add a binder and mix them evenly; after stirring and trapping the materials, select an appropriate pressure according to the size of the product for compression molding, and dry at a temperature of 110°C to obtain a green body (moisture content in the kiln <0.5%); then Firing at 1350°C for 2 hours, the cordierite-mullite-silicon carbide refractory material is obtained.

As shown in Figure 1, the cordierite-mullite-silicon carbide refractory material prepared in the embodiment of the present invention, the cordierite-mullite matrix introduced between the silicon carbide aggregate particles is not only wrapped in the silicon carbide bone The surface of the material particles is combined by chemical bonding, the mixing is uniform, and the combination is stable and firm, which is conducive to improving the quality of silicon carbide refractories.

Claims (7)

1. a kind of tri compound SiC based refractories, it is characterised in that：Including base-material and bonding agent, the composition of the base-material For 30~40wt% of carborundum aggregate, 10~55wt% of silicate mineral, 5~35wt% of technical grade aluminum raw material, cordierite 10 ~35wt%, the dosage of the bonding agent are 6~12wt% of base-material.

2. tri compound SiC based refractories according to claim 1, it is characterised in that：The silicate mineral is Andalusite, sillimanite, kyanite or bauxite；The technical grade aluminum raw material is α-Al₂O₃、γ-Al₂O₃Or Al (OH)₃。

3. tri compound SiC based refractories according to claim 1, it is characterised in that：The carborundum aggregate Granularity is 60~325 mesh, and the granularity of silicate mineral is 180~250 mesh, and the granularity of technical grade aluminum raw material is 180~250 The granularity of mesh, cordierite is 250~325 mesh.

4. tri compound SiC based refractories according to claim 1, it is characterised in that：The bonding agent is concentration The PVA solution of 5wt%.

5. the preparation method of one of the claim 1-4 tri compound SiC based refractories, it is characterised in that：It will be described After base-material mixing, bonding agent is added and is uniformly mixed；The green compact obtained after compression moulding, drying, are sintered, after firing i.e. Dichroite-mullite-SiC based refractories are made.

6. the preparation method of tri compound SiC based refractories according to claim 5, it is characterised in that：It is described dry Its moisture of green compact ＜ 0.5% after dry.

7. the preparation method of tri compound SiC based refractories according to claim 5, it is characterised in that：The burning Junction temperature is 1300~1400 DEG C, and firing time is 1~2h.