CN102584283A - Sintered silicon nitride and magnesium oxide-carbide refractory and preparation method thereof - Google Patents

Abstract

The invention specifically relates to a fired silicon nitride bonded magnesia-carbon refractory material and a preparation method thereof. The technical scheme is: firstly mix 50~75wt% fused magnesia particles or sintered magnesia particles, 3~20wt% % graphite powder and 5-40wt% elemental silicon powder as raw materials, plus 1-10wt% binder of the raw materials, mixed for 5-30 minutes, pressed into shape, and dried at 60-200°C for 12-36 hours ; Then keep warm for 1-30 hours under nitrogen atmosphere and 1280-1410°C, then heat up to 1450-1700°C under nitrogen atmosphere, keep warm for 3-8 hours for sintering, and cool naturally. The invention has the characteristics of abundant raw materials, good oxidation resistance, high high temperature strength, less carbon addition to molten steel, good corrosion resistance and long service life. The ladle lining and refining furnace lining of clean steel such as carbon steel and ultra-low carbon steel are beneficial to the improvement of steel quality.

Description

A kind of fired silicon nitride bonded magnesium oxide-carbonaceous refractory material and preparation method thereof

technical field

The invention belongs to the technical field of fired refractory materials, and in particular relates to a fired silicon nitride combined magnesium oxide-carbon refractory material and a preparation method thereof.

Background technique

In the past two decades, carbon-containing refractory materials have been widely used in high-performance refractory materials due to their excellent performance. However, in the actual application of this material, there are problems such as carburization of molten steel and low strength during high temperature use, which affects the quality of clean steel and the life of the lining material. Looking for new alternative oxide-non-oxide refractory materials is refractory The focus of attention of the material and metallurgical industry.

Although magnesium oxide-carbon refractory has its special advantages such as good thermal shock stability and strong slag erosion resistance, it has poor carburization behavior and oxidation resistance to molten steel, low high-temperature strength, and low-temperature magnesium oxide and carbon. The performance of magnesium vapor and carbon monoxide can be reduced by the reaction, but the performance of the material cannot be ignored, because silicon nitride has the characteristics of non-wetting to molten metal, no carbon addition to molten steel, and the promotion of material reaction and sintering after high-temperature oxidation to improve material strength. During the preparation process, the silicon nitride binding phase is reacted, and the phenolic resin-bonded magnesia-carbon refractory material is converted into a fired silicon nitride-bonded magnesia-carbon refractory material, thereby solving the above-mentioned problems.

Contents of the invention

The purpose of the present invention is to overcome the defects of the prior art, and the purpose is to provide a fired silicon nitride bonded oxidation compound with rich raw materials, good oxidation resistance, high high temperature strength, less carburization of molten steel, good corrosion resistance and long service life. Magnesium-carbonaceous refractory material and its preparation method.

In order to achieve the above object, the technical solution adopted by the present invention is: first mix 50~75wt% fused magnesia particles or sintered magnesia particles, 3~20wt% graphite powder and 5~40wt% elemental silicon powder as raw materials , adding 1-10wt% binder of the raw materials, mixing for 5-30 minutes, pressing and molding, and drying at 60-200°C for 12-36 hours. Then raise the temperature to 1280~1410°C under nitrogen atmosphere, keep it warm for 1~30 hours, then raise the temperature to 1450~1700°C under nitrogen atmosphere, keep it warm for 3~8 hours, and cool naturally to prepare fired silicon nitride Combined magnesia-carbonaceous refractories.

In the above technical scheme: MgO content of fused magnesia particles ≥ 90wt%, SiO ₂ content ≤ 10wt%, particle size of fused magnesia particles ≤ 8mm; MgO content of sintered magnesia particles ≥ 90wt%, SiO ₂ content ≤ 10wt%, the particle size of sintered magnesia particles is ≤8mm; the C content of graphite is ≥90wt%, and the particle size is ≤0.1mm; the Si content of elemental silicon is ≥90wt%, and the particle size is ≤0.1mm; the binder is calcium lignosulfonate, One of sodium lignosulfonate, sulfurous acid pulp waste liquid, industrial dextrin powder, polyvinyl alcohol, and phenolic resin.

Due to the adoption of the above technical scheme, the fused magnesia particles or sintered magnesia particles, graphite powder and elemental silicon powder used in the present invention have a wide range of sources, and silicon nitride is used as a binding phase in the prepared material, not only reacting magnesia and graphite Combined into one, and because the generated silicon nitride wraps the graphite, the oxidation resistance of the graphite is improved, and the carbon addition to the molten steel is less, which improves the performance of the material. The fired silicon nitride combined with magnesium oxide-carbon refractory material not only has high refractoriness, but also has excellent slag resistance and thermal shock resistance, which can ease the stress caused by repeated heating and cooling in use, thereby avoiding cracking of the lining material and flaking. In addition, the SiO ₂ and MgO produced by the oxidation of silicon nitride at high temperature dissolve into the slag, increasing the content of SiO ₂ and MgO in the slag, increasing the viscosity of the slag, and inhibiting slag penetration.

In the present invention, the preparation method of firing silicon nitride combined with magnesia-carbon refractory material replaces the traditional phenolic resin combined with MgO-C material, which can improve the thermal shock resistance and erosion resistance of the material. It is a new type of furnace lining material suitable for non-ferrous metal and iron and steel smelting equipment, especially suitable for the ladle lining and refining furnace lining of clean steel such as low carbon steel and ultra-low carbon steel, which is conducive to the improvement of steel quality.

Therefore, the present invention has the characteristics of abundant raw materials, good oxidation resistance, high high temperature strength, less carburization of molten steel, good corrosion resistance and long service life; It is suitable for the ladle lining and refining furnace lining of clean steel such as low carbon steel and ultra-low carbon steel, which is beneficial to the improvement of steel quality.

Detailed ways.

The present invention will be further described below in conjunction with specific embodiment, is not the limitation of its protection scope:

In order to avoid repetition, the technical parameters of the raw materials involved in this specific embodiment are described as follows, and will not be repeated in the examples: the MgO content of the fused magnesia particles and the sintered magnesia particles are all ≥ 90wt%, and _{the SiO} content is ≤ 10wt%, the particle size of both fused magnesia particles and sintered magnesia particles is ≤8mm; the C content of graphite is ≥90wt%, and the particle size is ≤0.1mm; the Si content of elemental silicon is ≥90wt%, and the particle size is ≤0.1mm.

Example 1

A fired silicon nitride bonded magnesium oxide-carbonaceous refractory material and a preparation method thereof. First, 50~55wt% of fused magnesia particles, 15~20wt% of graphite powder and 25~30wt% of elemental silicon powder are used as raw materials, and 7~10wt% of the raw materials are added as a binder, and mixed for 5~10 minutes. Press molding, dry at 60~110°C for 12~18 hours; then heat up to 1280~1310°C under nitrogen atmosphere, keep warm for 25~30 hours, and then heat up to 1450~1500°C under nitrogen atmosphere , heat preservation for 7 to 8 hours, and natural cooling to prepare fired silicon nitride combined with magnesia-carbon refractories.

In this embodiment, the binder is calcium lignosulfonate.

Example 2

A fired silicon nitride bonded magnesium oxide-carbonaceous refractory material and a preparation method thereof. First, 60~65wt% sintered magnesia particles, 10~15wt% graphite powder and 25~30wt% elemental silicon powder are used as raw materials, plus 3~7wt% binder of the raw materials, mixed for 10~15 minutes, and pressed Molding, drying at 100~150°C for 18~24 hours; then heating up to 1310~1340°C under nitrogen atmosphere, keeping it warm for 20~25 hours, and then heating up to 1500~1550°C under nitrogen atmosphere, Keep warm for 6-7 hours, cool naturally, and make fired silicon nitride combined with magnesia-carbon refractory.

In this embodiment, the binding agent is polyvinyl alcohol.

Example 3

A fired silicon nitride bonded magnesium oxide-carbonaceous refractory material and a preparation method thereof. First, 65~70wt% fused magnesia particles, 3~10wt% graphite powder and 20~27wt% elemental silicon powder are used as raw materials, and 1~4wt% of the raw material is added as a binder, and mixed for 15~20 minutes, Press molding, dry at 150~180°C for 24~30 hours; then heat up to 1340~1370°C under nitrogen atmosphere, keep warm for 15~20 hours, and then heat up to 1550~1600°C under nitrogen atmosphere , keep warm for 5-6 hours, and cool naturally to prepare fired silicon nitride combined with magnesia-carbon refractory.

In this embodiment, the binding agent is industrial dextrin powder.

Example 4

A fired silicon nitride bonded magnesium oxide-carbonaceous refractory material and a preparation method thereof. First, 70~75wt% sintered magnesia particles, 15~20wt% graphite powder and 5~10wt% elemental silicon powder are used as raw materials, plus 7~10wt% binder of the raw materials, mixed for 20~25 minutes, and pressed Molding, drying at 60~110°C for 30~36 hours; then heating up to 1370~1410°C under nitrogen atmosphere, keeping it warm for 5~10 hours, and then heating up to 1600~1650°C under nitrogen atmosphere, Keep warm for 4~5 hours, cool naturally, and make fired silicon nitride combined with magnesia-carbon refractory.

In this embodiment, the binder is calcium lignosulfonate.

Example 5

A fired silicon nitride bonded magnesium oxide-carbonaceous refractory material and a preparation method thereof. First, 55~60wt% sintered magnesia particles, 15~20wt% graphite powder and 20~25wt% elemental silicon powder are used as raw materials, plus 7~10wt% binder of the raw materials, mixed for 25~30 minutes, and pressed Molding, drying at 110~140°C for 30~36 hours; then heating up to 1370~1410°C under nitrogen atmosphere, keeping it warm for 1~8 hours, and then heating up to 1650~1700°C under nitrogen atmosphere, Keep warm for 3-4 hours, cool naturally, and make fired silicon nitride combined with magnesia-carbon refractory.

In this embodiment, the binder is sodium lignosulfonate.

Example 6

A fired silicon nitride bonded magnesium oxide-carbonaceous refractory material and a preparation method thereof. First, 65~70wt% fused magnesia particles, 15~20wt% graphite powder and 10~15wt% elemental silicon powder are used as raw materials, and 3~7wt% of the raw materials are added as a binder, and mixed for 15~20 minutes, Press and form, dry at 80~120°C for 24~36 hours; then heat up to 1350~1380°C under nitrogen atmosphere, keep warm for 5~10 hours, and then heat up to 1450~1500°C under nitrogen atmosphere , heat preservation for 7 to 8 hours, and natural cooling to prepare fired silicon nitride combined with magnesia-carbon refractories.

In this embodiment, the binding agent is sulfurous acid pulp waste liquid.

Example 7

A fired silicon nitride bonded magnesium oxide-carbonaceous refractory material and a preparation method thereof. First, 60~65wt% sintered magnesia particles, 15~20wt% graphite powder and 15~20wt% elemental silicon powder are used as raw materials, plus 3~7wt% binder of the raw materials, mixed for 10~15 minutes, and pressed Molding, drying at 180~200°C for 24~36 hours; then heating up to 1350~1380°C under nitrogen atmosphere, keeping it warm for 5~10 hours, and then heating up to 1450~1500°C under nitrogen atmosphere, Keep warm for 7-8 hours, cool naturally, and make fired silicon nitride combined with magnesia-carbon refractory.

In this embodiment, the binder is phenolic resin.

Example 8

A fired silicon nitride bonded magnesium oxide-carbonaceous refractory material and a preparation method thereof. First, 60~65wt% fused magnesia particles, 5~10wt% graphite powder and 30~35wt% elemental silicon powder are used as raw materials, and 3~7wt% of the raw materials are added as a binder, and mixed for 15~20 minutes. Press molding, dry at 80~120°C for 24~36 hours; then heat up to 1350~1380°C under nitrogen atmosphere, keep warm for 10~15 hours, and then heat up to 1500~1550°C under nitrogen atmosphere , keep warm for 5-7 hours, and cool naturally to prepare fired silicon nitride combined with magnesia-carbon refractory.

In this embodiment, the binding agent is sulfurous acid pulp waste liquid.

Example 9

A fired silicon nitride bonded magnesium oxide-carbonaceous refractory material and a preparation method thereof. First, 55~60wt% sintered magnesia particles, 5~10wt% graphite powder and 35~40wt% elemental silicon powder are used as raw materials, plus 3~7wt% binder of the raw materials, mixed for 15~20 minutes, and pressed Molding, drying at 80~120°C for 24~36 hours; then heating up to 1380~1410°C under nitrogen atmosphere, keeping it warm for 5~10 hours, and then heating up to 1450~1500°C under nitrogen atmosphere, Keep warm for 7-8 hours, cool naturally, and make fired silicon nitride combined with magnesia-carbon refractory.

In this embodiment, the binder is sodium lignosulfonate.

the

The fused magnesia particles or sintered magnesia particles, graphite powder and elemental silicon powder used in this specific embodiment have a wide range of sources. In the prepared material, silicon nitride is used as a binding phase, which not only combines magnesium oxide and graphite into one, but also Since the generated silicon nitride wraps the graphite, the oxidation resistance of the graphite is improved, the addition of carbon to the molten steel is less, and the performance of the material is improved. The fired silicon nitride combined with magnesium oxide-carbon refractory material not only has high refractoriness, but also has excellent slag resistance and thermal shock resistance, which can ease the stress caused by repeated heating and cooling in use, thereby avoiding cracking of the lining material and flaking. In addition, the SiO ₂ and MgO produced by the oxidation of silicon nitride at high temperature dissolve into the slag, increasing the content of SiO ₂ and MgO in the slag, increasing the viscosity of the slag, and inhibiting slag penetration.

The preparation method of this specific embodiment for firing silicon nitride combined with magnesia-carbon refractory material replaces the traditional phenolic resin combined with MgO-C material, which can improve the performance of the material such as thermal shock resistance and erosion resistance. It is a new type of furnace lining material suitable for non-ferrous metal and iron and steel smelting equipment, especially suitable for the ladle lining and refining furnace lining of clean steel such as low carbon steel and ultra-low carbon steel, which is conducive to the improvement of steel quality.

Therefore, this specific embodiment has the characteristics of rich raw materials, good oxidation resistance, high high temperature strength, less carbon addition to molten steel, good corrosion resistance and long service life. The prepared refractories are suitable for non-ferrous metals and iron and steel smelting equipment The new furnace lining material is especially suitable for the ladle lining and refining furnace lining of clean steel such as low carbon steel and ultra-low carbon steel, which is conducive to the improvement of steel quality.

Claims (7)

1. A preparation method for firing silicon nitride combined with magnesia-carbon refractories, characterized in that 50~75wt% of fused magnesia particles or sintered magnesia particles, 3~20wt% of graphite powder and 5~40wt% elemental silicon powder is used as raw material, plus 1~10wt% binder of the raw material, mixed for 5~30 minutes, pressed and molded, dried at 60~200°C for 12~36 hours; then in a nitrogen atmosphere Raise the temperature to 1280~1410°C under the conditions, keep the temperature for 1~30 hours, then raise the temperature to 1450~1700°C under the nitrogen atmosphere, keep the temperature for 3~8 hours, and cool naturally. 2. the preparation method of firing silicon nitride combined with magnesia-carbon refractories according to claim 1, is characterized in that the MgO content of the fused magnesia particles ≥ 90wt%, _SiO Content ≤ 10wt%, The particle size of fused magnesia particles is ≤8mm. 3. the preparation method of firing silicon nitride combined with magnesia-carbon refractories according to claim 1 is characterized in that the MgO content of the sintered magnesia particles is ≥ 90wt%, and _the SiO content is ≤ 10wt%. The particle size of magnesia particles is ≤8mm. 4. The method for preparing fired silicon nitride bonded magnesia-carbon refractory material according to claim 1, characterized in that the C content of the graphite is ≥90wt%, and the particle size is ≤0.1mm. 5. The method for preparing fired silicon nitride bonded magnesium oxide-carbonaceous refractories according to claim 1, characterized in that the Si content of the elemental silicon is ≥ 90 wt%, and the particle size is ≤ 0.1 mm. 6. the preparation method of firing silicon nitride combined with magnesium oxide-carbonaceous refractory material according to claim 1, is characterized in that described binding agent is calcium lignosulfonate, sodium lignosulfonate, sulfurous acid pulp One of waste liquid, industrial dextrin powder, polyvinyl alcohol, and phenolic resin. 7. The fired silicon nitride bonded magnesia-carbon refractory prepared by the method for preparing the fired silicon nitride bonded magnesia-carbon refractory according to any one of claims 1 to 6.