阅读说明：本技术 一种高强度、高寿命塞棒及其制备方法 (high-strength and long-service-life stopper rod and preparation method thereof ) 是由 蔡伟 殷若光 孙华云 李明京 蔡衍坤 殷佩如 于 2019-10-11 设计创作，主要内容包括：本发明涉及耐火材料制品技术领域,具体涉及一种高强度、高寿命塞棒及其制备方法,所述塞棒的原料包括白刚玉、镁铝合金粉、石墨、抗氧化剂和液体树脂；所述方法包括以下步骤：(1)称取原料搅拌,得到泥料；(2)将泥料烘干后装入密闭容器中困料；(3)将困好的泥料装填入橡胶模具中；(4)经压力成型,得到半成品；(5)将成型后的半成品装入烘干窑中,经烘干固化；(6)用车床将烘干后的半成品加工至规则形状后涂刷一层防氧化涂料；(7)待涂料完全干燥后,将产品装入烧成窑烧成,保温制得成品塞棒。本发明提供的塞棒抗折强度可达到15-23MPa,耐压强度可达到60MPa以上,使用寿命可延长3-5小时。(The invention relates to the technical field of refractory material products, in particular to a high-strength and long-service-life stopper rod and a preparation method thereof, wherein the stopper rod comprises the following raw materials of white corundum, magnesium aluminum alloy powder, graphite, an antioxidant and liquid resin; the method comprises the following steps: (1) weighing raw materials and stirring to obtain pug; (2) drying the pug, and then putting the pug into a closed container for ageing; (3) filling the trapped pug into a rubber mold; (4) performing pressure forming to obtain a semi-finished product; (5) putting the formed semi-finished product into a drying kiln, and drying and curing; (6) processing the dried semi-finished product into a regular shape by using a lathe, and then brushing a layer of anti-oxidation coating; (7) and after the coating is completely dried, putting the product into a firing kiln for firing, and preserving heat to obtain the finished stopper rod. The breaking strength of the stopper rod provided by the invention can reach 15-23MPa, the compressive strength can reach more than 60MPa, and the service life can be prolonged by 3-5 hours.)

1. the high-strength and long-service-life stopper rod is characterized in that raw materials of the stopper rod comprise white corundum, magnesium aluminum alloy powder, graphite, an antioxidant and liquid resin, wherein the white corundum comprises 36-mesh white corundum, 80-mesh white corundum and 320-mesh white corundum.

2. a high strength, long life stopper rod as claimed in claim 1, wherein said stopper rod comprises the following raw materials in parts by weight: 20-30 parts of 36-mesh white corundum, 10-30 parts of 80-mesh white corundum, 20-40 parts of 320-mesh white corundum, 5-10 parts of magnesium aluminum alloy powder, 10-20 parts of graphite, 3-5 parts of antioxidant and 10-15 parts of liquid resin.

3. A high strength, long life stopper rod as claimed in claim 2, wherein said stopper rod comprises the following raw materials in parts by weight: 27.5 parts of 36-mesh white corundum, 25 parts of 80-mesh white corundum, 35 parts of 320-mesh white corundum, 7.5 parts of magnesium aluminum alloy powder, 15 parts of graphite, 4 parts of antioxidant and 12 parts of liquid resin.

4. A high strength, long life stopper rod as claimed in claim 1, wherein said magnesium aluminum alloy powder is 200 mesh magnesium aluminum alloy powder.

5. A method for preparing a stopper rod with high strength and long service life is characterized by comprising the following steps:

(1) adding white corundum, magnesium aluminum alloy powder, graphite, an antioxidant and liquid resin which are weighed according to a certain proportion into a stirrer, and stirring for 10-30min to obtain pug, wherein the white corundum comprises 36-mesh white corundum, 80-mesh white corundum and 320-mesh white corundum;

(2) drying the stirred pug for 20-30min, and filling the pug into a closed container for ageing;

(3) filling the trapped pug into a rubber mold;

(4) Placing the rubber mold into a cold isostatic press, and forming under the pressure of 50-120MPa to obtain a semi-finished product;

(5) putting the formed semi-finished product into a drying kiln, and drying and curing at the temperature of 200-;

(6) Processing the dried semi-finished product into a regular shape by using a lathe, and then brushing a layer of anti-oxidation coating;

(7) and after the coating is completely dried, putting the product into a sintering kiln, sintering at the temperature of 1100-1300 ℃, and preserving heat for 8-13h to obtain the finished stopper rod.

6. A method for preparing a high strength and long life stopper rod according to claim 5, wherein the 36 mesh white corundum, 80 mesh white corundum, 320 mesh white corundum, magnesium aluminum alloy powder, graphite, antioxidant and liquid resin in the step (1) are in a mass ratio of (20-30): (10-30): (20-40): (5-10): (10-20): (3-5): (10-15).

7. the method for preparing a high-strength and long-life stopper rod according to claim 6, wherein the mass ratio of the 36-mesh white corundum, the 80-mesh white corundum, the 320-mesh white corundum, the magnesium aluminum alloy powder, the graphite, the antioxidant and the liquid resin in the step (1) is 27.5: 25: 35: 7.5: 15: 4: 12.

8. The method for preparing a high strength and long life stopper rod according to claim 5, wherein the raw materials of the oxidation preventing coating of the step (6) include boron glass powder, kaolin, industrial silicon powder, gum arabic and water.

Technical Field

The invention relates to the technical field of refractory material products, in particular to a high-strength and long-service-life stopper rod and a preparation method thereof.

Background

The stopper rod is a refractory material rod which is arranged in a steel containing barrel and controls the opening and closing of a water gap and the flow rate of molten steel by means of lifting and lowering displacement in the continuous casting process of the molten steel.

In recent years, along with the acceleration of the molten steel smelting rhythm of a steel mill and the stricter control of smelting cost, the performance requirement on the stopper rod is higher and higher. However, the breaking strength and compressive strength of the conventional stopper rod are low, so that the phenomenon of flow control runaway of the stopper rod often occurs in actual production, the continuous casting process of a billet is seriously affected, and the use requirement at the present stage cannot be met.

Therefore, it is necessary to provide a stopper rod with high strength and long service life and a preparation method thereof.

disclosure of Invention

aiming at the technical problems of low strength and short service life of the existing stopper rod, the invention provides the stopper rod with high strength and long service life and the preparation method thereof, the breaking strength of the stopper rod can be improved to 15-23MPa from 6-10MPa of the existing stopper rod, the compressive strength can be improved to more than 60MPa from 30-40MPa of the existing stopper rod, and the service life can be prolonged by 3-5 hours.

In a first aspect, the invention provides a high-strength and long-life stopper rod, which comprises the raw materials of white corundum, magnesium aluminum alloy powder, graphite, an antioxidant and liquid resin.

Further, the white corundum comprises 36-mesh white corundum, 80-mesh white corundum and 320-mesh white corundum.

Further, the stopper rod comprises the following raw materials in parts by weight: 20-30 parts of 36-mesh white corundum, 10-30 parts of 80-mesh white corundum, 20-40 parts of 320-mesh white corundum, 5-10 parts of magnesium aluminum alloy powder, 10-20 parts of graphite, 3-5 parts of antioxidant and 10-15 parts of liquid resin.

Further, the stopper rod comprises the following raw materials in parts by weight: 27.5 parts of 36-mesh white corundum, 25 parts of 80-mesh white corundum, 35 parts of 320-mesh white corundum, 7.5 parts of magnesium aluminum alloy powder, 15 parts of graphite, 4 parts of antioxidant and 12 parts of liquid resin.

further, the magnesium-aluminum alloy powder is 200-mesh magnesium-aluminum alloy powder.

Further, the weight ratio of magnesium powder to aluminum powder in the magnesium-aluminum alloy powder is 1: 1.

further, the antioxidant is boron carbide.

Further, the liquid resin is phenolic resin.

in a second aspect, the present invention provides a method of making a high strength, long life stopper rod, the method comprising the steps of:

(1) adding the white corundum, the magnesium-aluminum alloy powder, the graphite, the antioxidant and the liquid resin which are weighed according to the proportion into a stirrer, and stirring for 10-30min to obtain pug;

(2) Drying the stirred pug for 20-30min, and filling the pug into a closed container for ageing;

(3) filling the trapped pug into a rubber mold;

(4) placing the rubber mold into a cold isostatic press, and forming under the pressure of 50-120MPa to obtain a semi-finished product;

(5) putting the formed semi-finished product into a drying kiln, and drying and curing at the temperature of 200-;

(6) processing the dried semi-finished product into a regular shape by using a lathe, and then brushing a layer of anti-oxidation coating;

(7) And after the coating is completely dried, putting the product into a sintering kiln, sintering at the temperature of 1100-1300 ℃, and preserving heat for 8-13h to obtain the finished stopper rod.

Further, the white corundum in the step (1) comprises 36-mesh white corundum, 80-mesh white corundum and 320-mesh white corundum.

Further, the mass ratio of the 36-mesh white corundum, the 80-mesh white corundum, the 320-mesh white corundum, the magnesium aluminum alloy powder, the graphite, the antioxidant and the liquid resin in the step (1) is (20-30): (10-30): (20-40): (5-10): (10-20): (3-5): (10-15).

Further, the mass ratio of the 36-mesh white corundum, the 80-mesh white corundum, the 320-mesh white corundum, the magnesium aluminum alloy powder, the graphite, the antioxidant and the liquid resin in the step (1) is 27.5: 25: 35: 7.5: 15: 4: 12.

Further, the raw materials of the anti-oxidation coating in the step (6) comprise boron glass powder, kaolin, industrial silicon powder, gum arabic and water.

the invention has the beneficial effects that:

The invention provides a high-strength and long-service-life stopper rod, which comprises white corundum, magnesium aluminum alloy powder, graphite, an antioxidant and liquid resin, wherein the melting points of magnesium and aluminum are low, so that a slight liquid phase can be generated in the sintering process of the product, gaps among the raw materials such as the white corundum are further filled, the bonding performance, the anti-fracture performance and the pressure resistance of the product are greatly enhanced, and the thermal shock stability of the product is improved.

the invention also provides a preparation method of the stopper rod with high strength and long service life, and the sintering time is shortened by 5-8h compared with the traditional sintering process by adopting the process, so that the sintering cost is greatly reduced, and the utilization rate of a kiln is enhanced.

Detailed Description

In order to make those skilled in the art better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

screening example

Screening the white corundum, the white corundum particle size distribution and the magnesium-aluminum alloy powder in the stopper rod raw material by adopting a single factor method; the above raw materials were prepared into a stopper rod according to the same preparation method, and the breaking strength and compressive strength thereof were tested.

the preparation method of the stopper rod comprises the following steps:

(1) Adding the white corundum, the magnesium-aluminum alloy powder, the graphite, the antioxidant and the liquid resin which are weighed according to the proportion into a stirrer, and stirring for 20min to obtain pug;

(2) drying the stirred pug for 25min, and then putting the pug into a closed container for ageing;

(3) Filling the trapped pug into a rubber mold;

(4) Placing the rubber mold into a cold isostatic press, and forming under the pressure of 80MPa to obtain a semi-finished product;

(5) putting the formed semi-finished product into a drying kiln, and drying and curing at 250 ℃;

(6) Processing the dried semi-finished product into a regular shape by using a lathe, and then brushing a layer of anti-oxidation coating;

(7) and after the coating is completely dried, putting the product into a sintering kiln, sintering at 1200 ℃, and preserving heat for 10 hours to obtain the finished stopper rod.

1. White corundum fraction

The weight parts of the white corundum are screened by adopting a single-factor method, the breaking resistance and the pressure resistance of the stopper rod prepared in the screening example are tested, and the raw material proportion and the performance test result of the screening example are shown in the following table 1.

Table 1 raw material ratios of screening examples and performance test results

As can be seen from Table 1, when the amount of the white corundum is gradually increased, the breaking strength and the compressive strength of the stopper rod are increased and then tend to be stable, particularly when the amount of the white corundum is 50-100 parts by weight, the breaking strength and the compressive strength are obviously improved when the amount of the white corundum is less, and when the amount of the white corundum is more than 100 parts by weight, the change of the breaking strength and the compressive strength is small, which indicates that more white corundum does not contribute much to the improvement of the breaking strength and the compressive strength of the stopper rod. Based on the weight portion, the white corundum obtained by screening is 50-100 portions, and is preferably 87.5 portions.

2. White corundum particle size distribution

On the basis that the white corundum is determined to be 50-100 parts by weight, preferably 87.5 parts by weight, the usage amount of other raw materials is kept unchanged, the particle size distribution of the white corundum is screened, the breaking resistance and the pressure resistance of the stopper rod prepared in the screening example are tested, and the particle size distribution and the performance test results of the white corundum in the screening example are shown in the following table 2.

table 2 white corundum particle size distribution and performance test of screening examples

As can be seen from table 2, in screening example 11, when the mesh number is selected to be 36 mesh, 80 mesh and 320 mesh, the flexural strength and compressive strength are most improved, which is mainly determined by two reasons: firstly, a wider particle size distribution is needed for improving the stacking density of the white corundum, and secondly, a smaller particle size distribution is needed for improving the sintering activity so as to improve the specific surface area of the white corundum. By combining the two factors, the three kinds of white corundum in the screening example 11 are matched in size, and fine particles/powder of 80 meshes and 320 meshes are filled in gaps formed by the closely-arranged 36-mesh white corundum, so that the white corundum forms a more compact stacking structure; meanwhile, the specific surface area of the white corundum in the screening example 11 can be effectively increased by 80-mesh white corundum and more 320-mesh white corundum, and the mobility of particles is enhanced, so that the sintering activity is improved. Although the performance of the screening example 13 is close to that of the screening example 11, the particle size is generally smaller, so that flying dust is easily formed in production, the production environment is affected, and the problem of insufficient raw materials is also caused. Therefore, the screening resulted in optimum particle size distributions of 36 mesh, 80 mesh and 320 mesh.

the applicant also continuously optimizes the particle size distribution of the white corundum on the basis of the screening example 11, and on the basis of three kinds of white corundum of 36 meshes, 80 meshes and 320 meshes, 5 meshes of white corundum and/or 400 meshes of white corundum are added, and meanwhile, the weight parts of the white corundum with different particle sizes are adjusted, so that the total weight part of the white corundum is kept unchanged at 87.5 parts. The breaking strength and compressive strength of the stopper rod sintered by the same preparation method are tested, and the result shows that when the grain size of the white corundum exceeds 3, the improvement on the performance of the stopper rod is not obvious and has no practical significance.

3. parts of magnesium aluminum alloy powder

When the white corundum is determined to be 50-100 parts by weight, preferably 87.5 parts by weight, and the white corundum has the granularity of 36 meshes, 80 meshes and 320 meshes, the magnesium-aluminum alloy powder parts are screened, the breaking resistance and the pressure resistance of the stopper rod prepared in the screening example are tested, and the magnesium-aluminum alloy powder parts and the performance test results of the screening example are shown in the following table 3. Magnesium powder in the magnesium-aluminum alloy powder: the aluminum powder is 1: 1.

Table 3 parts of magnesium aluminum alloy powder in screening example and performance test

As can be seen from Table 3, when the weight portion of the magnesium-aluminum alloy powder is between 5 and 10, the increase of the flexural strength and the compressive strength is obvious, and when the weight portion exceeds 10, the strength increment becomes small, which indicates that the addition of the magnesium-aluminum alloy powder exceeding 10 does not bring obvious positive effect on the improvement of the stopper rod performance. That is, on the basis of the raw material composition, 5-10 parts of magnesium-aluminum alloy powder can better cover gaps formed by stacking among the raw materials after being melted, so that the stopper rod is combined more tightly, and the fracture resistance and the pressure resistance of the stopper rod are improved; when the magnesium-aluminum alloy powder is less than 5 parts, part of pores can not be filled, so that the stopper rod has an uneven phenomenon and lower product performance; when the weight of the magnesium-aluminum alloy powder exceeds 10 parts, the magnesium-aluminum alloy powder is excessive, so that the screened weight part of the magnesium-aluminum alloy powder is 5-10 parts, and the preferred weight part is 7.5 parts.

comparative example 1

comparative example 1 the magnesium aluminum alloy powder in screening example 17 was changed to magnesium aluminum spinel in equal parts by weight, and the selection of other raw materials and the preparation method of the stopper were the same as those in screening example 17. The performance of the stopper rods obtained in screening example 17 and comparative example 1 was measured, and the results are shown in table 4 below.

TABLE 4 Performance test of screening example 17 and comparative example 1

Performance index	Flexural strength/MPa	compressive strength/MPa
			screening example 17	22.72	62.53
Comparative example 1	7.37	50.66

The melting point of the magnesium aluminate spinel is higher, and the magnesium aluminate spinel can not be melted into a slight liquid phase which can fill gaps among white corundum at the firing temperature of the preparation process of the invention, so that the improvement on the breaking strength and the compressive strength of the stopper rod is limited.