KR19980048902A - Flame Retardant Powder - Google Patents

Abstract

The present invention relates to a powder spray material for thermally repairing damaged parts of acid, neutral and basic refractory materials used in incinerator glass melting furnaces, electric furnaces, etc., including various industrial furnaces, vacuum degassing facilities, ladles, tundish and heating furnaces. The purpose is to provide fireproof powder material for firefighting, which can be repaired at high temperature during furnace operation, especially as a fireproof powder repair material for long service life of the furnace equipment and improvement of fish beds.

The present invention for achieving the above object relates to a fireproof powder material for use in flames containing 0.2-10% by weight of short fibers having a fiber length of 0.2 mm or less in a conventional fired powder for use for coated or uncovered flames. It is a technical point.

Description

Flame Retardant Powder

The present invention relates to a powder spray material for thermally repairing damaged parts of acid, neutral and basic refractory materials used in incinerator glass melting furnaces, electric furnaces, etc., including various industrial furnaces, vacuum degassing facilities, ladles, tundish and heating furnaces. More specifically, the present invention relates to a fireproof powder material for flame retardant which can be repaired at a high temperature during furnace operation as a fireproof powder repair material for long life and productivity improvement of a furnace equipment.

Flame spray repair method as a hot repair technology for damaged parts of industrial furnace refractories is a kind of ceramic that generates refractory powders by melting and semi-melting by spraying refractory powder materials into them by generating high-temperature and high-speed flames over 2000 ℃. Corresponds to the welding method. In particular, the furnace refractories for the steel industry are generally used at high temperatures of 1350 ° C. or higher, and therefore, refractory powder materials for flame repair also use high melting point powder materials having a melting point of 1650 ° C. or higher.

Such refractory powders for flame can be roughly classified into uncoated refractory powders such as magnesia-based, alumina-spinel-based and silica-based coatings and coated refractory powders having low melting point materials coated on the refractory powders. .

The reason for this distinction is that materials such as magnesia and alumina in refractory powders have melting points of 2850 ° C and 2015 ° C, respectively, and do not melt at all during a very short residence time of about 0.1-0.2 seconds in a flame of 2000-2600 ° C. Therefore, in order to adhere the thermal spray material to the damaged refractory surface at this flame temperature, a small amount of a low melting point material, a composite material such as converter slag, wollastonite, cement, or the like must be added or coated, and aluminum and silicon are exothermicly reacted by oxidation. This is because metal powders such as magnesium-aluminum, alloy powder, coke powder, and the like can be added and sprayed to attach them.

Known techniques so far known generally fall into the following categories. In other words,

1) Refractory powder for magnesia-oxide type flame which coated particle surface of high melting point refractory material powder adjusted to 200-10㎛ particle size with ultrafine powder of sintered oxide with average particle diameter 10-0.1㎛ (Japan Patent Publication No. 61-186258)

2) Thermal spraying material manufactured by coating metal powder with particle size of 44 μm or less on high melting point material such as magnesia (Japanese Patent Publication No. 60-161379)

3) A method of manufacturing a thermal spraying material by adding coke powder for the purpose of increasing the flame temperature and improving the adhesion rate of the thermal spraying material (Japanese Patent Publication No. 62-41772).

4) A method of coating a magnesia particle with a fine low melting point material (Korean Patent Application No. 93-23742) or the like is known.

However, the conventional thermal spray materials have the following problems.

That is, since the thermal spray material of 1) is magnesia, a poorly soluble material having a melting temperature of 2850 ° C., silica is a sinterable oxide (SiO) because it does not melt at a flame temperature of 2500-2600 ° C. due to propane gas and oxygen. ₂ ), alumina (Al ₂ O ₃ ), spinel (spinel) and the like is characterized in that the surface of the magnesia particles, but this is a method of coating the oxide of a relatively high melting point to the magnesia particles, the adhesion rate of about 66-73% This is very low economical and there is a problem that the industrial practicality is inferior.

In addition, the thermal spraying material of 2) uses only an oxidative pyrogenic metal powder in a high melting point raw material, so that the high melting point raw material is not sufficiently melted, and thus the spraying efficiency is about 60%.

In addition, the thermal spraying material of 3) has the same drawbacks as the thermal spraying material of 2) by adding and using coke powder.

In addition, the thermal spraying material of 4) is manufactured by coating a low melting point powder having a maximum particle diameter of 44 μm or less on the magnesia particles, but the fluidity is somewhat reduced, but the adhesion efficiency to the base material is improved.

Each of the conventional thermal spraying materials has advantages and disadvantages, but as shown in FIG. There is a common problem involving the damage 6 of the thermal sprayed body 1 due to thermal shock.

According to the present invention, the flowability of the sprayed material is slightly lower than that of the spray-coated sprayed material, but shortly after the spraying of the conventional powdered sprayed material by adding and dispersing short fibers in the refractory powder material within a range without problems of transportability in the flame spraying device. The purpose of the present invention is to provide a fire-resistant powder material for flame which can suppress the thermal shock damage of the sprayed body, thereby improving the strength and durability of the sprayed body.

1 a) is a cross-sectional view of a sprayed body made of a conventional fire-resistant refractory powder material

b) is a cross-sectional view of the sprayed body by the refractory powder used for the flame of the present invention

Figure 2 a) is a block diagram of the coating type refractory powder material for use in flames of the present invention

b) is a block diagram of an uncoated fireproof powder material for use in flames of the present invention

* Description of the symbols for the main parts of the drawings *

1: spray construction layer

2: base material

3: Intergranular material in construction layer

4: alumina particles

5: crack in the construction layer

6: crack

7: Short fibers

8: Low melting point material coated on alumina particles

9: Granulated particles made of low melting point material

10: Alumina-silica-magnesia composite particle

The present invention for achieving the above object relates to a fire-resistant fire-resistant powder material containing 0.2-10% by weight of short fibers having a fiber length of 0.2 mm or less in a conventional fire-resistant fire-proof powder material for coated or uncoated.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

The present invention includes a short fiber in the refractory powder material in order to drastically improve the thermal spraying defects of the thermal spraying material of the conventional magnesia-based, alumina-spinel-based, silica-based coated spherical powder or coated refractory powder. To this end, the short fibers are not easily melted within a short residence time of about 0.1-0.3 seconds in a flame of 2000-2600 ° C., and do not easily form a component and a eutectic point of the thermal spray material on the state diagram. If it is a kind of thing which can maintain the original shape properly in a sprayed body, it is applicable, and a more preferable kind is aluminum oxide fiber, zirconium oxide fiber, silicon carbide fiber, carbon fiber, etc.

Such short fibers are basically applicable only if they are shorter than the maximum particle size of the refractory powder used for flame. The reason for this is that when the ceramic filament fiber having a maximum particle size of the thermal spray material is contained, the fluidity of the thermal spray material is not only deteriorated decisively, but also is a direct cause of serious defects in the transport of the thermal spray equipment.

Usually, since the maximum particle diameter of the flame retardant powder used for flame is 0.2 mm or less, the length of short fiber should be 0.21 mm or less, but it is most ideal to have a length of about 50% of the maximum particle diameter of powder spray material. At this time, the aspect ratio of the short fibers does not matter.

According to the present invention, it is preferable to contain 0.2-10% by weight of the short fibers having the length as described above, for the reason of 0.2% by weight or less, only the additional process occurs according to the addition of the fiber to increase the adhesion rate or strength However, the effect of reducing the cracks in the sprayed body is insufficient and the strength of the sprayed body is slightly improved when it exceeds 10% by weight.

On the other hand, it will be described through the first, second, and third degree the effect that the thermal spraying material is added to the refractory powder used for flames under the conditions as described above to prevent the thermal spray damage. As shown in FIG. 1, in the case of a conventional thermal spraying material (FIG. 1 (a)), defects, that is, cracks 6, are generated on the surface and inside of the thermal sprayed body 1 due to thermal shock caused by quenching immediately after spraying. In this case, in the case of the thermal spraying material of the invention in which a predetermined amount of the short fibers 7 is added, the occurrence of such cracks is suppressed in the thermal spraying body 1 of FIG. 1 (b), thereby improving the toughness and strength of the thermal spraying body. You can get it.

At this time, the thermal spraying material which is the refractory powder material of the present invention used is the same type as the second figure (a) in which the short fiber 7 is added and dispersed in the coated refractory powders 4 and 8 manufactured by a conventional method. There is a mold as shown in FIG. 2 (b) in which the short fibers 7 are added and dispersed in an uncoated fireproof powder 10 prepared by combining, mixing, molding, firing, and classifying the raw materials.

Hereinafter, the present invention will be described in detail through examples.

EXAMPLE

After spraying the refractory powder used for the flame composition as shown in Table 1 with the spraying speed of 50kg / hr, flame generating condition LPG 15N㎥ / hr, O ₂ 75N㎥ / hr, and then spraying the refractory surface, various characteristics were measured. The results are shown in Table 1 below.

TABLE 1

* 1: Spray-coated MgO 60% powder spraying material with a particle diameter of 0.21 mm or less

* 2: Alumina-Spinel-based powder spraying material having a particle diameter of 0.21 mm or less

* 3: Silica-based powder spraying material having a particle diameter of 0.21 mm or less

* 4: A fiber having a particle diameter of 0.21 mm or less

* 5: ◎ (No occurrence) ○ (Trace) △ (Minor occurrence) × (Surface defect due to large amount of microcracks)

As shown in Table 1, Inventive Example (1-3) in which aluminum oxide short fibers were added to MgO 60% grade magnesia-coated fireproof powder was compared to Comparative Example (1) without adding short fibers. Was insignificantly lowered but the strength was improved and the porosity was relatively good.

Moreover, the invention example (4-6) which added the appropriate amount of short fiber to the uncoated fire-proof powder material, or the general specification was excellent.

On the other hand, in the comparative example (8) having 0.2% or less of the short fiber addition amount, there was no crack reduction effect. When the addition amount of the short fiber excessively exceeded 10% by weight, as in Comparative Example (10-11), the flowability of the thermal spraying material drastically increased. The pulsation phenomenon frequently occurred during spraying, and the sprayed body also showed the opposite effect due to the decrease in strength and the decrease in adhesion rate.

Such ceramic short fibers may be added not only in one kind but also in two or three kinds, but it is economical to add one kind because the addition process is complicated and the synergy is scarce. In addition, the addition of short fibers is generally possible if it is a conventional powder kneading method, but the pressure kneading method is not recommended due to the reduction of the particle size or the breaking of the coated particles, and is preferably a V-type mixer. If the mixing device is not applied to the thermal spray material itself, such as can be used, it is more effective to use a mixing device with an accessory such as a hook (hook) to mechanically disperse the ceramic short fibers.

In the case of thermally repairing damaged refractory parts of various industrial furnaces with the thermal spraying powder spraying material reinforced with ceramic short fibers of the present invention, in particular, in the case of thermally thermally repairing a furnace body under an quenching environment immediately after thermal spraying, A drastic improvement in the toughness and strength of the thermal sprayed body can be achieved, thus extending the life of the furnace body and reducing the refractory cost.

Claims (3)

A fire-resistant powder material for flames containing 0.2-10% by weight of short fibers having a fiber length of 0.2 mm or less in a normal coated or uncoated fire-resistant powder material. The fireproof powder material for a flame according to claim 1, wherein the uncoated fireproof powder is magnesia-based, alumina-spinel-based or silica-based. The refractory powder material for use in flame according to claim 1, wherein the short fiber is one of aluminum oxide short fiber, zirconium oxide short fiber, silicon carbide short fiber and carbon fiber.