JPH1171183A - Flame spraying material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a slag-compounded flame spraying material with basicity improved in serviceability. SOLUTION: This flame spraying material is obtained by including 5-40 wt.% of sintered calcia-magnesia clinker comprising 35-80 wt.% of CaO, 18-63 wt.% of MgO and 1.8-7 wt.% of Fe2 O3 with the content of CaO+MgO totaling >=93 wt.%, 30-70 wt.% of sintered magnesia clinker and/or fused magnesia, and 10-50 wt.% of slag. Because the sintered calcia-magnesia clinker moderately containing Fe2 O3 also contains 18-63 wt.% of MgO higher in melting point than CaO, formation of low-melting substances is suppressed despite being capable of improving the adhesivity of this material owing to the presence of Fe2 O3 , thereby securing the corrosion resistance of this material, resulting in improving the serviceability of this flame spraying material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a basic flame sprayed material having excellent adhesiveness and corrosion resistance.

[0002]

2. Description of the Related Art Damaged linings in industrial kilns such as converters, melting furnaces, AOD furnaces, ladles, tundishes, and vacuum degassing furnaces are repaired by flame spraying.
In this method, a refractory fine powder is passed through a high-speed, high-temperature flame, and is melted or semi-molten to be sprayed on a damaged portion. According to this flame spraying method, a dense and high-strength repair body structure is formed, and an excellent repair effect is obtained.

Hitherto, as a thermal spraying material used for the flame spraying, basic properties of MgO—CaO system have been proposed.
For example, in JP 63-107873 discloses calcareous clinker, magnesia clinker and slag material blended with, calcareous clinker and magnesia clinker in JP 63-107872 containing Fe ₂ O ₃ of a specific amount ( The material to which slag is added (if necessary) is shown.

[0004]

The thermal sprayed material having a basic property is particularly excellent in corrosion resistance among flame sprayed materials, and has been the mainstream material of the prior art. However, on the other hand, there is a disadvantage that the adhesiveness (adhesive strength to the surface to be repaired) is poor due to the high melting point of the basic material. In view of this, conventionally, an improvement in adhesiveness has been achieved by blending slag, which is a low-melting substance.

[0005] The slag is indispensable in terms of adhesiveness. As mentioned above, the use of calcareous clinker containing a certain amount of Fe ₂ O ₃ has been proposed, but the adhesion is not sufficient unless used in combination with slag. However, the addition of slag simultaneously lowers the corrosion resistance of the sprayed material, so that it is not possible to add an amount sufficient to obtain sufficient adhesiveness.

The present invention has been made in view of such circumstances, and has as its object to provide a basic spray material having excellent adhesion and corrosion resistance.

[0007]

According to the present invention, a chemical composition of CaO: 35 to 80 wt% and MgO: 18 to 63 are used.
wt%, Fe ₂ O _3: includes 1.8~7wt%, the C
Sintered calcia having a total content of aO and MgO of 93% by weight or more
Magnesia clinker is 5 to 40 wt%, and sintered magnesia clinker and / or electrofused magnesia is 30 to 40 wt%.
This is a flame spray material containing 70 wt% and 10 to 50 wt% of slag. Further, another refractory raw material may be added in an amount of 30 wt% or less.

According to the present invention, it is possible to obtain a basic spray material having excellent adhesiveness and corrosion resistance as compared with conventional materials. This is considered to be due to the following reasons. The sintered calcia-magnesia clinker used in the present invention is:
The Fe ₂ O ₃ component containing 1.8~7wt%. And F
By containing e ₂ O ₃ , it is well compatible with slag as a solvent that is simultaneously mixed with the thermal spray material, and the adhesiveness of the thermal spray material is improved.

The idea of improving the adhesiveness by including a specific amount of Fe ₂ O ₃ component in the clinker is the same idea as the calcareous clinker disclosed in the above-mentioned JP-A-63-107872. However, in the case of calcareous clinker, its main component, CaO, reacts with Fe ₂ O ₃ and C
aO.Fe ₂ O ₃ , 2CaO.Fe ₂ O ₃ or Ca
Generates a low melting point substance such as O · 2Fe ₂ O _3, the corrosion resistance of the thermal spray material is greatly reduced due to the reduction of the bone material itself corrosion resistant.

On the other hand, the sintered calcia-magnesia clinker used in the present invention contains 18 to 63 wt% of MgO having a melting point higher than that of CaO in the component, and thus, Fe ₂
Generation of a low-melting substance due to O ₃ is suppressed. As a result, it is possible to improve the adhesion by including Fe ₂ O ₃ without lowering the corrosion resistance. In addition, ordinary sintered calcia-magnesia clinker has a problem of causing peeling damage due to spalling due to a large thermal expansion coefficient of MgO. Since the sprayed material is dense, spalling due to thermal expansion is remarkable. On the other hand, the sintered calcia-magnesia clinker used in the present invention also has an effect of preventing a decrease in spalling resistance due to the thermal shock buffering action of the Fe ₂ O ₃ component.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the chemical component is CaO:
35 to 80 wt%, MgO: 18 to 63 wt%, Fe ₂
O ₃ : 1.8 to 7 wt%, and 5 to 40 wt% of a sintered calcia-magnesia clinker having a total amount of 93 wt% or more of CaO and MgO. The proportion of the chemical component of the sintered calcia-magnesia clinker used in the present invention affects the properties of the thermal spray material. That is, CaO is 35w
When the content is less than t% or the content of MgO exceeds 63% by weight, the slag penetration resistance and the spalling resistance of the sprayed material are inferior. M
When gO is less than 18 wt% or CaO exceeds 80 wt%, the corrosion resistance and digestion resistance are poor. If the total amount of CaO and MgO is less than 93 wt%, the corrosion resistance is poor.

Further, the sintered calcia used in the present invention is
-In the chemical composition of the magnesia clinker_TwoO
_ThreeIs less than 1.8 wt%, the adhesiveness is poor, and 7 wt%
%, The corrosion resistance is poor. Fe_TwoO_ThreeEven more preferred
The optimum range is 2 to 7 wt%. Sintered calcia-magne
There are synthetic and natural products. Synthetic products are sea
Manufactured by adding slaked lime to magnesium hydroxide obtained from water etc.
The sintered calcia-magnesia used in the present invention
The clinker is Fe_TwoO_ThreeFe by adding the component_TwoO _ThreeBut
Adjust so as to be in the range of 1.8 to 7 wt%. Natural products
Is manufactured by sintering dolomite ore.
What is used in this is Fe_TwoO_ThreeAdd the ingredients and add Fe
_TwoO_ThreeIs adjusted to be in the range of 1.8 to 7 wt.
The sintering temperature is about 1700-2000 for both synthetic and natural products
C is preferred.

The above-mentioned sintered calcia-magnesia clinker has effects of adhesion and corrosion resistance, but the corrosion resistance alone is insufficient. In the present invention, sintered magnesia clinker and / or electrofused magnesia are combined for imparting corrosion resistance. Sintered magnesia clinker or electrofused magnesia preferably has a high MgO purity, but a high-purity product is expensive.
It is used in consideration of economy and the like from those of wt% or more.

The types of slag are converter slag, blast furnace slag,
There are electric furnace slag, desulfurization slag, etc.
Select to use. Chemical composition is SiO_Two, CaO, Fe
_TwoO _Three, Al_TwoO_ThreeEtc. as a main component. Occupy spray material
If the ratio is less than 10 wt%, the adhesion is poor, and 50 wt%
%, The corrosion resistance decreases. Sintered calcia mentioned above
Magnesia clinker and sintered magnesia clinker
And / or refractory raw materials other than fused magnesia
You may mix | blend in the range of wt% or less. An example is
Lombite, alumina, silica, alumina-silica, zircon
, Zirconia, spinel, carbon, carbide, nitride, acid
Lithium oxide, titania, silicon and the like. Also, F
e_TwoO_ThreeWith less than 1.8% or more than 7%
It may be a calcia-magnesia clinker.

As a melting aid, olivine, wollastonite and the like may be used in combination other than slag. However, it is necessary that the total amount with the slag does not exceed the range of 10 to 50 wt%. The particle size of each of the above compounds is
As in the case of the conventional thermal spraying material, the thickness is 1 mm or less, preferably 50 mm in average, in consideration of the jetting property from the nozzle and the melting property by the flame.
To 150 μm. Conventionally, the thermal spraying method is performed using a thermal spraying machine using propane gas, acetylene, hydrogen, kerosene or the like as a fuel. The flame sprayed material of the present invention is, for example, a converter, a melting furnace, an AOD furnace, a ladle, a tundish, a vacuum degassing furnace,
In addition to forming and repairing the lining of industrial kilns such as mixed iron cars, electric furnaces, incinerators, induction furnaces, and heating furnaces,
It can also be used for forming, coating and repairing refractory articles.

[0016]

EXAMPLES Table 1 shows the chemical components of each compound used in Examples and Comparative Examples. Table 2 shows the compositions of the thermal spray materials of the examples and comparative examples and the test results. FIG. 1 is based on the thermal sprayed material of the composition of Example 1 shown in Table 2, and changes only the Fe ₂ O ₃ component of the sintered calcia-magnesia clinker in the composition. 4 is a graph showing the relationship between the Fe ₂ O ₃ component and the adhesiveness of the thermal spray material.

For the thermal spraying, a propane-oxygen flame spraying apparatus was used. Flame temperature is about 250 at the highest temperature
It was 0 ° C. The sprayed material was adjusted to an average particle size of 88 to 90 μm and supplied into the flame at a rate of 3 kg / min. The surface to be sprayed was a vertical wall of MgO-C brick having a surface temperature of about 1200 ° C. The test shown in Table 2 was performed by cutting out the sprayed body in a state where the sprayed body was attached to the sprayed surface, and performing the following method.

Adhesion: The shear strength between the sprayed surface and the sprayed material was determined in an electric furnace at 1200 ° C. Corrosion resistance: The sprayed body was rotationally eroded to determine the erosion dimension. The erosion agent was a combination of steel slab and converter slag at a weight ratio of 1: 1. Spalling resistance; 1500 ° C x 2 sprayed material in electric furnace
After heating for 0 min, the mixture was forcibly air-cooled and the state of crack generation was visually observed.

Actual test: A 100 t converter lined with MgO-C brick was repaired by flame spraying, and then the number of usable charges was determined. At that time, the supply rate of the thermal spray material into the flame was 35 to 45 Kg / min.

[0020]

[Table 1]

[0021]

[Table 2]

From the graph of FIG. 1, it can be confirmed that Fe ₂ O ₃ in the sintered calcia-magnesia clinker is effective in improving the adhesiveness. Further, as shown in the test results shown in Table 2, the examples of the present invention had both adhesiveness, corrosion resistance, and spalling resistance, and an excellent repair effect was obtained in an actual machine test. In contrast, small synthetic sintered magnesia than the limited range of the content of Fe ₂ O ₃ is the invention - as calcia Comparative Example 1 The clinker blended, less natural than the limited range of the content of Fe ₂ O ₃ is the invention Comparative Example 2 in which the sintered magnesia-calcia clinker was blended was inferior in adhesion and spalling resistance. Fe ₂ O ₃ Comparative blended sintered calcia clinker additives example 3, synthesis sintered magnesia of Comparative Example 4, Fe ₂ O ₃ addition ratio of the slag is too high - calcia clinker Comparative Example 5 ratio is too high the car, Poor corrosion resistance. Comparative Example 6, in which the proportion of natural sintered magnesia-calcia clinker to which Fe ₂ O _{3 was} added was small, was poor in adhesion. Comparative Example 7, in which a natural sintered magnesia-calcia clinker in which the content of Fe ₂ O ₃ is larger than the limited range of the present invention, is excellent in adhesion, but inferior in corrosion resistance.

[0023]

As shown in the test results of the above examples,
According to the present invention, it is possible to obtain a thermal sprayed material having both adhesiveness, corrosion resistance and spalling resistance. as a result,
For example, if the sprayed material of the present invention is used as a repair material for various kinds of molten metal kilns, effects such as a reduction in repair man-hours and repair materials by improving the durability of the furnace, and further, an improvement in furnace operation rate can be obtained. Can and is very useful.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the ratio of a Fe ₂ O ₃ component in a sintered calcia-magnesia clinker and the adhesiveness of a thermal spray material.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Kakuichi Murakami 1-3-1 Shinhama, Arai-machi, Takasago City, Hyogo Prefecture Inside Harima Ceramics Co., Ltd. (72) Hiroaki Kubo 1-3-1, Shinhama, Arai-machi, Takasago City, Hyogo Prefecture No. Harima Ceramics Co., Ltd.

Claims (2)

[Claims] 1. A chemical composition of CaO: 35-80 wt%, M
_{gO: 18~63wt%, Fe 2 O} 3: 1.8~7wt
%, And the total amount of CaO and MgO is 93 wt% or more.
%, 30 to 70 wt% of sintered magnesia clinker and / or electrofused magnesia, and 10 to 50 wt% of slag.
%. 2. The chemical composition of CaO: 35-80 wt%, M
_{gO: 18~63wt%, Fe 2 O} 3: 1.8~7wt
%, And the total amount of CaO and MgO is 93 wt% or more.
%, Sintered magnesia clinker and / or electrofused magnesia in an amount of 30 to 70 wt%,
A flame sprayed material containing 0 wt% or less and slag of 10 to 50 wt%.