JPH05330931A - Thermal spraying repairing material - Google Patents

Abstract

PURPOSE:To obtain a thermal spraying repairing material having a strong adhesiveness between a formed sprayed layer and a furnace surface even in case of a low temperature, e.g. 600 deg.C, of a damaged part (a part to be repaired) of a furnace, without decreasing a working circumstance owing to little noise in spraying and excellent in workability. CONSTITUTION:2-20wt.% metallic silicon powder having <=100mum average size and 0.5-5wt.% aluminum-magnesium alloy powder having <=100mum average particle size are compounded to a main component of a refractory fine powder.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to, for example, an irregular shaped fire-resistant lining material generated during the use of a kiln, a molten metal container or the like, or a locally damaged portion of a furnace wall such as a broken joint, a crack or a peeling The present invention relates to a thermal spray repair material used for repairing.

[0002]

2. Description of the Related Art In a kiln such as a heating furnace, a soaking furnace, and a coke oven, and a molten metal container such as a tundish, a ladle, and a gutter, there is a problem during use. Local damage may occur to standard fire resistant lining and brick walls.

When such localized damage occurs, conventionally, a so-called wet spray repair method is carried out by mixing water or an inorganic binder liquid and refractory powder with a spray nozzle and spraying the mixture on the damaged wall of the furnace wall. It is general to repair by.

However, in the above-mentioned conventional wet spray repair method, when the temperature of the furnace wall surface is 600 ° C. or higher, there is a problem that the adhesiveness of the spray refractory material becomes insufficient and the durability deteriorates.

Further, Japanese Patent Laid-Open No. 4-13308 discloses that
Exothermic oxidative material with an average particle size of 50 μm or less (silicon,
(Aluminum) particles are mixed with particles of a non-combustible refractory material and the mixture is burned while being sprayed onto one surface to form a cohesive refractory aggregate on that surface. Has a problem that when the damaged portion of the furnace wall surface at 800 ° C. or lower is sprayed and repaired, the adhesiveness of the sprayed layer is deteriorated and the durability is lowered.

Further, Japanese Patent Application Laid-Open No. 2-45110 discloses a mixed refractory made of refractory oxide particles or particles of easily oxidizable metal of 50 μm or more which burn to form refractory oxide. The material, for example with flammable gas,
In a method of repairing a refractory by injecting into a stream of a combustion-supporting gas, a theoretical combustion equivalent of the combustible gas supplied and an amount equal to or more than three times the theoretical oxidation reaction equivalent of the easily oxidizable metal or metalloid to be supplied. A flame spray repair method is disclosed, which comprises supplying a total amount of the combustion-supporting gas of

In this flame spraying repair method, the furnace wall surface can be heated (preheated) by the combustion flame of combustible gas.
It has the feature that a thermal spraying repair layer with excellent adhesion is formed even on the furnace wall surface at 0 ° C or less, but because the flammable gas is used, its safety measure equipment becomes large, Lance is material + LPG (flammable gas) pipe, O
_Since it becomes a triple pipe of ₂ pipes and a water cooling pipe, there is a problem that the workability at the time of thermal spray repair is deteriorated due to the large weight, the noise during the thermal spray is large, and the working environment is deteriorated.

The present invention solves the above problems, and the temperature of the damaged portion (repair portion) of the furnace wall is, for example, 600.
An object of the present invention is to provide a thermal spray repair material that can obtain a high adhesive strength even when the temperature is as low as about 0 ° C, has a low noise during thermal spraying, and has excellent workability during thermal spray repair.

[0009]

[Means for Solving the Problems] In order to achieve the above object, the inventors conducted various experiments and studies, and in the process, obtained the following findings.

The thermal spraying method in which the refractory fine powder is melted by the heat of oxidation reaction of the metallic silicon powder and the metallic aluminum powder (metallic powder) does not require the supply of a combustible gas and does not require a passage therefor. It has the characteristics that it is light in weight, the repair work is easy, and the noise generated during thermal spraying is extremely low due to only the sound generated when the oxygen reacts with the metal powder.

However, in this thermal spraying method, metallic silicon powder and metallic aluminum powder are used as the oxidizable metallic powder, and the adhesion becomes insufficient when the furnace wall surface is 800 ° C. or lower.

If metallic magnesium powder is added to the mixed powder of metallic silicon powder and metallic aluminum powder described above, cordierite (2MgO.2Al ₂ O ₃ .5SiO ₂ ) is formed at the bond portion due to the oxidation reaction during thermal spraying.
A melt close to is produced. Since this cordierite material has a low melting point, it has a large adhesiveness even when the temperature of the furnace wall surface is 800 ° C. or less, and has a small coefficient of linear thermal expansion, and therefore has excellent thermal shock resistance. There is.

Therefore, it is conceivable to use the cordierite raw material as a refractory fine powder, but in that case, the thermal sprayed layer as a whole has a low melting point and durability is deteriorated, which is not preferable. In addition, MgO, Al ₂ O ₃ , SiO ₂
A method of mixing powders and spraying is conceivable, but MgO, A
It is difficult for the l ₂ O ₃ and SiO ₂ powders to melt and become cordierite.

On the other hand, when the metallic silicon powder and the aluminum-magnesium alloy powder are mixed and used, only a matrix having a property close to cordierite is easily formed. It is also possible to use a mixture of metal magnesium powder and metal aluminum powder instead of the aluminum-magnesium alloy powder, but since the metal magnesium powder is easily ignited and dangerous, it is much better to use the aluminum-magnesium alloy powder. Excellent in safety.

The inventors have completed the present invention by further conducting experiments and studies based on the above findings.

That is, the thermal spray repair material of the present invention has 5 to 20% by weight of metallic silicon (Si) powder having an average particle size of 100 μm or less, and an average particle size of 100 μm or less, based on the refractory fine powder as the main component. Aluminum (Al) and magnesium (Mg) alloy powder of 0.5 to 5% by weight are blended.

In the thermal spray repair material of the present invention, the surface of the refractory fine powder is melted by the oxidation reaction of the metallic silicon powder and the aluminum / magnesium alloy powder during thermal spraying, and the metallic silicon powder and the aluminum / magnesium alloy powder are oxidized. When it is processed, SiO ₂ , Al
It becomes a ternary melt of ₂ O ₃ and MgO.

The SiO ₂ .Al ₂ O ₃ .MgO
The ternary refractory has a lower melting point than the SiO ₂ · Al ₂ O ₃ refractory produced by the oxidation of metallic silicon powder and metallic aluminum powder, and therefore it is between the furnace wall surface and the thermal spray material (sprayed surface). The adhesive strength of is improved.

The ternary substance of SiO ₂ , Al ₂ O ₃ and MgO has a low coefficient of linear expansion and is excellent in thermal shock resistance.

In the thermal spraying repair material of the present invention, if the content of the metallic silicon powder is less than 5% by weight, the amount of heat generation becomes small and the surface of the refractory fine powder cannot be melted sufficiently, which is not preferable. Further, if the content of the metallic silicon powder exceeds 20% by weight, the surface of the refractory material is excessively melted and dripping occurs on the surface of the sprayed layer, which is not preferable.

If the content of the aluminum-magnesium alloy powder is less than 0.5% by weight, combustion (oxidation reaction) does not continue, which is not preferable. In addition, aluminum
If the content of the magnesium alloy powder exceeds 5.0% by weight, the surface of the refractory fine powder is excessively melted, which causes sagging on the surface of the sprayed layer, which is not preferable.

Therefore, the content of the metallic silicon powder is preferably in the range of 5 to 20% by weight, and the content of the aluminum-magnesium alloy powder is
It is preferably in the range of 0.5 to 5% by weight.

When the average particle size of the metallic silicon powder and the aluminum-magnesium alloy powder exceeds 100 μm, the oxidation reaction is difficult to occur, and a considerable amount of unburned (unoxidized) metal remains in the sprayed layer. The average particle size of the metal silicon powder and the aluminum-magnesium alloy powder is preferably 100 μm or less because the combustion (oxidation) rate decreases and a good sprayed layer cannot be formed.

[0024]

EXAMPLES Hereinafter, examples of the present invention will be shown together with comparative examples to explain the features of the present invention in more detail.

Chamotte powder (fine powder of refractory material), metallic silicon powder, and aluminum-magnesium alloy powder were prepared, and these were mixed in the proportions shown in Table 1 to prepare a thermal spray repair material. In the thermal spray repair material of this example, chamotte powder, which is superior in heat-resistant spalling resistance to alumina-based and silica-based refractory, is used as the refractory fine powder.

For comparison, a metal aluminum powder was used in place of the aluminum-magnesium alloy powder of the above example, and the raw materials were blended in the proportions shown in Table 1 to prepare a thermal spray repair material (comparative example). did.

[0027]

[Table 1]

Then, the spray-coated repair materials of Examples 1 and 2 and Comparative Examples 1 and 2 in Table 1 were spray-coated on the brick surface (furnace wall surface) at 600 ° C. and 800 ° C. to obtain the adhesive strength and compression strength of the sprayed layer. Well,
While measuring the porosity, the "heating-cooling cycle" for heating at 1200 ° C for 30 minutes and then air-cooling for 15 minutes was used.
A repeated spalling test was performed. The measurement results are shown in Table 1.

First, comparing Comparative Examples 1 and 2 with Examples 1 and 2 in the case where the brick surface at 800 ° C. was sprayed,
Regarding the adhesive strength and the compressive strength, Examples 1 and 2 are considerably higher than Comparative Examples 1 and 2, and the porosities of Comparative Examples 1 and 2 are slightly larger than those of Examples 1 and 2. You can see that it has become. Further, in the spalling test, some cracks were generated in the sprayed layers of Example 2 and Comparative Examples 1 and 2, but in Example 1, only a few minute cracks were recognized.

Next, comparing Comparative Examples 1 and 2 with Examples 1 and 2 in the case where the brick surface of 600 ° C. is sprayed,
The adhesive strength of Examples 1 and 2 is several times higher than that of Comparative Examples 1 and 2, and the compressive strength of Examples 1 and 2 is twice or more that of Comparative Examples 1 and 2. I understand. Further, it can be seen that the porosity is smaller in Examples 1 and 2 and about 1 / 1.5 of Comparative Examples 1 and 2.
As described above, in Examples 1 and 2, the adhesive strength was 1 MN / m ² even when the temperature of the sprayed brick surface was as low as 600 ° C.
(Approximately 10 kgf / cm ² ) or more (Specifically,
Example 1 is 1.2 MN / m ² , Example 2 is 1.8 MN / m ² .
/ M ² ), 0.3 MN / m ² of Comparative Example 1, and 0.
It can be seen that it is significantly superior to 1 MN / m ² . In addition, in the spalling test, in each of Comparative Examples 1 and 2 and Examples 1 and 2, minute cracks were only slightly recognized, and the cracks did not grow.

As described above, in the thermal spray repair material of the embodiment, the characteristics (adhesive strength, heat-resistant spalling property, etc.) that can be practically used are obtained even when the thermal spraying is performed at a low temperature of about 600 ° C. I found out that

[0032]

As described above, the thermal spray repair material of the present invention has an average particle size of 10 with respect to the refractory fine powder as the main component.
5 to 20% by weight of metallic silicon (Si) powder of 0 μm or less
And aluminum with an average particle size of 100 μm or less (Al)
Since the alloy powder of magnesium and magnesium (Mg) is mixed in an amount of 0.5 to 5% by weight, the temperature of the damaged portion (repaired portion) of the furnace wall is 6
Even when the temperature is as low as about 00 ° C., it is possible to form a sprayed layer having high adhesive strength to the damaged portion of the furnace wall and excellent in compressive strength and heat spalling resistance. Further, since no combustible gas is used, noise during thermal spraying can be suppressed to improve the working environment, and workability at the time of thermal spray repair can be improved.

Since the temperature change in the vicinity of the coke oven door (kiln mouth) is large, the thermal spray repair material used to repair damage near the kiln mouth is required to have excellent heat-resistant spalling properties. Also, when performing repair (spraying) work, the vicinity of the kiln is rapidly cooled and the temperature drops to about 600 ° C, so it is required to have excellent adhesiveness even at low temperatures. The thermal spray repair material of the present invention is particularly meaningful as such a thermal spray repair material in the vicinity of the kiln opening of a coke oven.

Claims (1)

[Claims] 1. A metal silicon (Si) powder having an average particle size of 100 μm or less with respect to the refractory fine powder as a main component.
Alloy powder of aluminum (Al) and magnesium (Mg) with an average particle size of 20% by weight and an average particle size of 100 μm or less 0.5 to
A thermal spray repair material characterized by containing 5% by weight.