RU2720337C1 - Mixture for production of refractory structural ceramic material - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: invention relates to refractory materials which can be used in ferrous and non-ferrous metallurgy as lining of blast-furnace, mine and other furnaces. Charge for production of refractory structural ceramic material contains, wt.%: carbide-silicon powders of fractions 4.0–1.5 mm; 1.5–0.5 mm; 0.5–0.25 mm; 0.25–0.07 mm and 0.07–0.001 mm – 60–92; industrial ground silica powder 5.0–25.0; aluminum powder 0.1–5.0; alumina 0.1–20.0; dextrin and / or calcium lingosulphonate 0.5–5.0, wherein silicon carbide powder fractions are taken from their total amount in the following ratios, wt%: 4.0–1.5mm – 10–0; 1.5–0.5 mm – 5–50; 0.5–0.25 mm – 3–25; 0.25–0.07 mm – 2–25; 0.07–0.001 mm – 2–20.

EFFECT: increased corrosion resistance and resistance to abrasive and erosion wear.

1 cl, 1 tbl, 11 ex

Description

The invention relates to refractory materials that can be used in the ferrous and non-ferrous metallurgy as a lining for blast furnaces, shaft and other furnaces.

In shaft furnaces for the melting of cathode copper, the refractory layer of silicon carbide lining also undergoes not only corrosion, but also intensive abrasive and erosive wear of the charge loaded through the upper loading hole. Refractory structural ceramic material from a charge of a coarser composition will better withstand abrasive and erosive wear.

In aluminum electrolyzers, the side lining of their silicon carbide refractory material undergoes both erosive wear by particles in the melt of the circulating electrolyte and gas corrosion of sodium fluoride vapor in the upper part of the bead. Refractory structural ceramic material from a charge of a finer-grained composition and containing, in addition to silicon carbide powder, silicon powder, aluminum powder and alumina, it will be better to resist gas corrosion by sodium fluoride vapor in the upper part of the board.

In the boilers of incineration plants, the lining of silicon carbide refractory is subjected to abrasion and erosion by the waste loaded into the boilers, corrosion by alkali fumes and the oxidative effects of air and flue gases. Refractory structural ceramic material from a charge of a finer-grained composition and containing, in addition to silicon carbide powder, silicon powder, aluminum powder and alumina, will better resist gas corrosion by alkali fumes, oxidative effects of air and flue gases, abrasive and erosive wear by loaded garbage.

A known composition for producing sialon-containing material, including sialon-containing powder, consisting of 35-70 wt.% Si ₃ Al ₃ O ₃ N ₅ , 15-35 wt.% SiAl ₄ O ₂ N ₄ , 10-20 wt.% 3C-SiC , 5-10 wt.% Al ₂ O ₃ with a particle size of not more than 150 nm, additionally hexagonal silicon carbide 6H-SiC 20-40% in the dimensional state 5000-50000 nm and yttrium oxide Y ₂ O ₃ , in the following ratio of components, wt.%: sialon-containing powder 50-75, 6H-SiC 20-40, Y ₂ O ₃ 5-10 (see the description of the invention to the patent of the Russian Federation No. 2359944 "Sialon-containing material and composition for its preparation", IPC C04B35 / 599, C04B35 / 5 69, published on June 27, 2009).

The disadvantages of this invention are:

- high temperature of the material (1750-1850 ° C);

- low resistance to corrosion, abrasive and erosive wear due to the small size of the particles in the charge composition;

- the use in the mixture of nanodispersed and scarce ultrapure materials, which leads to a very high cost of production and the inability to produce refractory materials on a mass scale.

Closest to the claimed mixture for producing a refractory structural ceramic material is a mixture for producing a refractory material from silicon carbide on a binder of predominantly β-sialon, consisting of 60-90 wt.% Silicon carbide powders with a size of less than 200 microns, up to 5 wt.% silicon oxide, from 8 to 25 wt.% silicon powder, from 1.5 to 5.5 wt.% aluminum, both in the form of a pure metal and in the form of compounds or mixtures of compounds: aluminum nitride, aluminum oxide, aluminum hydroxide and aluminum salts, and 2-17 wt.% times ligaments (see the description of the invention to US patent No. 5521129, IPC C04B35 / 565, C04B35 / 599, publ. 05.28.1996).

The preform is obtained by slip casting, then the preform is calcined in a nitriding medium at temperatures from 1300 to 1600 ° C and a refractory material is made of silicon carbide on a sialon bond.

The disadvantages of such a charge mixture are the multiphase of the resulting target refractory material and the grain composition of the mixture is too thin. The maximum grain size of silicon carbide powders is 200 μm, which limits the area of use of refractory material, for example, in blast furnaces, where refractory materials are exposed not only to high temperatures, but also to corrosion by molten slag, liquid metal, and abrasion, and erosion from moving insoluble pieces of loadable charge.

To increase the resistance to corrosion, abrasion and erosion, refractory materials that are necessary for use in metallurgy, it is advisable to use a coarser charge composition.

The technical task and the result of the invention is to increase the corrosion resistance to abrasion and erosion wear by obtaining a refractory structural ceramic material with a constant phase and coarse grain composition of the frame.

The technical result of the proposed technical solution is achieved in that the mixture to obtain a refractory structural ceramic material includes silicon carbide powders, silicon powder, aluminum and a temporary binder, while it contains silicon carbide powders of the following fractions 4.0 - 1.5 mm, 1.5 - 0 , 5 mm, 0.5 - 0.25 mm, 0.25 - 0.07 mm and 0.07 - 0.001 mm, aluminum in the form of aluminum powder and alumina, and as a temporary binder - dextrin and / or calcium lingosulfonate in the following ratio components, wt.%:

silicon carbide powders        60 -92 ground technical silicon powder         5.0-25.0 aluminum powder        0.1-5.0 alumina        0.1-20.0 calcium dextrin and / or lingosulfonate 0.5-5.0

  while fractions of silicon carbide powders are taken from their total amount in the following wt.%:

4.0 - 1.5 mm 10-50 1.5 - 0.5 mm   5-50  0.5 - 0.25 mm   3-25 0.25 - 0.07 mm   2-25 0.07 - 0.001 mm   2-20

The composition of the proposed mixture provides a refractory structural ceramic material, characterized by the necessary constant phase composition and coarse grain composition of the frame. Such a refractory structural ceramic material has increased corrosion resistance and resistance to abrasive and erosive wear.

The preparation of the mixture and obtaining from it a refractory structural ceramic material is as follows.

The production of refractory structural ceramic material begins with the preparation of the molding material. The preparation of the molding material involves dosing the components, followed by mixing.

The main stages of mixing is dry mixing and mixing with a curing agent, which is used as water or other curing agents, receiving a molding mass.

 To prepare the molding mass, the following charge composition is used:

- silicon carbide black or green fraction 7/12 (4.0-1.5 mm);

- silicon carbide black or green fraction 14/30 (1.5 - 0.5 mm);

- silicon carbide black or green fraction 36/70 (0.5 - 0.25 mm);

- silicon carbide black or green fraction 80/180 (0.25 - 0.07 mm); - silicon carbide black or green fraction 220F (0.07 - 0.001 mm);

-silicon technical ground;

- aluminum powder grade PAP-1, PAP-2 or other GOST 5494;

- acid corn dextrin yellow or fawn GOST 6034;

- calcium lignosulfonate brand Lignobond DD or Wafex Ca 122 or other brands;

- metallurgical alumina grades G000 to G0 GOST 30558 or non-metallurgical alumina grades GK GOST 30559.

After preparation, the molding mass is aged.

From the obtained molding material, the blanks of the refractory structural ceramic material are molded by pressing, vibrocompressing, ramming, slip casting, casting using concrete technology or vibrocasting. Then the products are kept for at least 12 hours in the premises of the workshop, after which they are dried. Drying of products is carried out in thermal units of a chamber or tunnel type. The heat carrier during drying can be natural gas combustion products, regenerated heat carrier, or electric energy. Drying temperature 110 - 150 ° С. Drying time is 12 - 120 hours, depending on the overall dimensions of the products, especially the thickness, and the molding method.

Then carry out high-temperature firing of products in a gaseous nitrogen atmosphere at temperatures of 1200 - 1600 ° C. As a result of firing, a refractory structural ceramic material is obtained, characterized by the necessary constant phase composition, and a coarse grain composition of the frame, represented by at least five fractions of silicon carbide, of which the largest fraction has a grain size of 1.5-4 mm. The grains of silicon carbide with a size of 1.5-4 mm are almost perfect, the crystal growth faces are preserved in them, respectively, their surface is small and the corrosion resistance is high.

Refractory structural material may have a porosity of 1 - 19% or more, depending on the application and the selected technology for forming blanks.

The obtained refractory structural material is used in the ferrous and non-ferrous metallurgy as a lining for blast furnaces, shaft and other furnaces. It can be used in the form of side lining of aluminum and magnesium electrolyzers and other thermal aggregates of non-ferrous metallurgy, as well as for incinerators and in mechanical engineering, and in other industries as refractory, heat-resistant, corrosion-resistant, structural, wear-resistant and impact-resistant material.

Example 1

Prepare a mixture of the following composition, wt. %:

Silicon carbide 60.0 Technical ground silicon 17.5 Alumina G00 12.0 PAP-2 aluminum powder 3.0 Dextrin and / or Calcium Lingosulfonate 3.0 Water 4,5

The fractions of silicon carbide are taken from their total amount in the following wt.% (From 60%):

 4.0 - 1.5 mm  19.0   1.5 - 0.5 mm  15.0   0.5 - 0.25 mm  8.5   0.25 - 0.07 mm  2.0   0.07 - 0.001 mm  15,5

Example 2

Prepare a mixture of the following composition, wt. %:

Silicon carbide 60.0 Technical ground silicon 25.0 Alumina G00 5.5 PAP-2 aluminum powder 2.0 Dextrin and / or Calcium Lingosulfonate 3.0 Water 4,5

The fractions of silicon carbide are taken from their total amount in the following wt.% (From 60%):

 4.0 - 1.5 mm  18.0   1.5 - 0.5 mm  20,0   0.5 - 0.25 mm  10.0   0.25 - 0.07 mm  10.0   0.07 - 0.001 mm  2.0

Example 3

Prepare a mixture of the following composition, wt. %:

Silicon carbide 60.0 Technical ground silicon 10.0 Alumina G00 15,5 PAP-2 aluminum powder 5,0 Dextrin and / or Calcium Lingosulfonate 5,0 Water 4,5

The fractions of silicon carbide are taken from their total amount in the following wt.% (From 60%):

 4.0 - 1.5 mm  20,0   1.5 - 0.5 mm  15.0   0.5 - 0.25 mm  8.0   0.25 - 0.07 mm  12.0   0.07 - 0.001 mm  5,0

Example 4

Prepare a mixture of the following composition, wt. %:

Silicon carbide 60.0 Technical ground silicon 8.0 Alumina G00 20,0 PAP-2 aluminum powder 5,0 Dextrin and / or Calcium Lingosulfonate 3.0 Water 4.0

The fractions of silicon carbide are taken from their total amount in the following wt.% (From 60%):

 4.0 - 1.5 mm  18.0   1.5 - 0.5 mm  20,0   0.5 - 0.25 mm  10.0   0.25 - 0.07 mm  10.0   0.07 - 0.001 mm  2.0

Example 5

Prepare a mixture of the following composition, wt. %:

Silicon carbide 80.0 Technical ground silicon 8.5 Alumina G00 3,5 PAP-2 aluminum powder 0.5 Dextrin and / or Calcium Lingosulfonate 3.0 Water 4,5

The fractions of silicon carbide are taken from their total amount in the following wt.% (From 80%):

(4.0 - 1.5 mm) 50,0  (1.5 - 0.5 mm) 11.0  (0.5 - 0.25 mm) 12.5  (0.25 - 0.07 mm) 2.0  (0.07 - 0.001 mm) 4,5

Example 6

Prepare a mixture of the following composition, wt. %:

Silicon carbide 80.0 Technical ground silicon 8.5 Alumina G00 3,5 PAP-2 aluminum powder 0.5 Dextrin and / or Calcium Lingosulfonate 3.0 Water 4,5

The fractions of silicon carbide are taken from their total amount in the following wt.% (From 80%):

 (4.0 - 1.5 mm) 10.0  (1.5 - 0.5 mm) 50,0  (0.5 - 0.25 mm) 8.0  (0.25 - 0.07 mm) 10.0  (0.07 - 0.001 mm) 2.0

Example 7

Prepare a mixture of the following composition, wt. %:

Silicon carbide 80.0 Technical ground silicon 8.5 Alumina G00 3,5 PAP-2 aluminum powder 0.5 Dextrin and / or Calcium Lingosulfonate 3.0 Water 4,5

The fractions of silicon carbide are taken from their total amount in the following wt.% (From 80%):

 (4.0 - 1.5 mm) 12.0   (1.5 - 0.5 mm) 30,0   (0.5 - 0.25 mm) 3.0   (0.25 - 0.07 mm) 25.0   (0.07 - 0.001 mm) 10.0

Example 8

Prepare a mixture of the following composition, wt. %:

Silicon carbide 80.0 Technical ground silicon 8.5 Alumina G00 3,5 PAP-2 aluminum powder 0.5 Dextrin and / or Calcium Lingosulfonate 3.0 Water 4,5

The fractions of silicon carbide are taken from their total amount in the following wt.% (From 80%):

 (4.0 - 1.5 mm) 40,0   (1.5 - 0.5 mm) 5,0   (0.5 - 0.25 mm) 25.0   (0.25 - 0.07 mm) 2.0   (0.07 - 0.001 mm) 8.0

Example 9

Prepare a mixture of the following composition, wt. %:

Silicon carbide 85.0 Technical ground silicon 6.0 Alumina G00 2.0 PAP-2 aluminum powder 0.5 Dextrin and / or Calcium Lingosulfonate 2,5 Water 4.0

The fractions of silicon carbide are taken from their total amount in the following wt.% (From 85%):

 (4.0 - 1.5 mm) 50,0   (1.5 - 0.5 mm) 10.0   (0.5 - 0.25 mm) 15,5   (0.25 - 0.07 mm) 5,0   (0.07 - 0.001 mm) 4,5

Example 10

Prepare a mixture of the following composition, wt. %:

Silicon carbide 85.0 Technical ground silicon 6.0 Alumina G00 2.0 PAP-2 aluminum powder 0.5 Dextrin and / or Calcium Lingosulfonate 2,5 Water 4.0

The fractions of silicon carbide are taken from their total amount in the following wt.% (From 85%):

 (4.0 - 1.5 mm)  30,0   (1.5 - 0.5 mm)  23.0   (0.5 - 0.25 mm)  10.0   (0.25 - 0.07 mm)  2.0   (0.07 - 0.001 mm)  20,0

Example 11

Prepare a mixture of the following composition, wt. %:

Silicon carbide 92.0 Technical ground silicon 5,0 Alumina G00 0.1 PAP-2 aluminum powder 0.1 Dextrin and / or Calcium Lingosulfonate 0.5 Water 2,3

The fractions of silicon carbide are taken from their total amount in the following wt.% (From 92%):

 (4.0 - 1.5 mm)  50,0   (1.5 - 0.5 mm)  12.0   (0.5 - 0.25 mm)  15.0   (0.25 - 0.07 mm)  10.0   (0.07 - 0.001 mm)  5,0

The resulting materials have high oxidation resistance according to ASTM C863 - 2010 and corrosion resistance according to ASTM C864 - 2010 and according to the Bettleham Steel method Bettleham Steel.

Examples of finished products indicating specific values of their open porosity, compressive strength at room temperature, and erosion resistance are given in the table.

Table

Index Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 Example 10 Example 11 Open porosity,% fifteen sixteen 17 17 thirteen sixteen sixteen fifteen sixteen 12 eighteen The tensile strength at compression at room temperature, MPa 180-190 175-185 160-170 180-190 190-200 170-180 170-180 180-190 190-200 230-240 150-160 Resistance to oxidation by the method of ASTM-C 863 by oxidation in water vapor at 1000 ^{° C} 0.25-0.30% 0.25-0.35% 0.40-0.50% 0.40-0.50% 0.25-0.35% 0.45-0.55% 0.50-0.60% 0.35-0.45% 0.35-0.45% 0.10-0.15% 0.30-0.50%

Claims (4)

The mixture to obtain a refractory structural ceramic material, including silicon carbide powders, silicon powder, aluminum and a temporary binder, characterized in that it contains silicon carbide powders of the following fractions 4.0-1.5 mm, 1.5-0.5 mm, 0, 5-0.25 mm, 0.25-0.07 mm and 0.07-0.001 mm, aluminum in the form of aluminum powder and alumina, and as a temporary binder - dextrin and / or calcium lingosulfonate in the following ratio of components, wt. %: silicon carbide powders 60–92 ground technical silicon powder 5.0–25.0 aluminum powder 0.1–5.0 alumina 0.1–20.0 calcium dextrin and / or lingosulfonate 0.5–5.0 while fractions of silicon carbide powders are taken from their total amount in the following wt.%: 4.0-1.5 mm 10-50 1.5-0.5 mm 5-50 0.5-0.25 mm 3–25 0.25-0.07 mm 2–25 0.07-0.001 mm 2–20