JP4493404B2 - Thermal spray material - Google Patents

Description

  The present invention relates to a thermal spray material used for repairing a refractory worn part such as an industrial furnace or a metal melting vessel, and in particular, refractory particles and low melting point particles are obtained by oxidation exothermic reaction of metal particles contained in the material. The present invention relates to a thermal spray material suitable for repairing a coke oven carbonization chamber using silica brick, among industrial furnaces, metal melting vessels, etc., which is melted and welded to a repair object.

Many steelworks coke ovens have been built for over 20 years, and especially the walls of the carbonization chamber need to be repaired. There is a thermal spray repair method as a technique for repairing while operating. The thermal spray repair method, Pula's Ma spraying, laser spraying, but there is a flame spraying, there is a need for large-scale apparatus.

On the other hand, the refractory particles are melted by the oxidation combustion reaction heat of the metal powder such as thermite reaction, there is a method of welding the repaired surface. This method is spraying the repairing surface of the high heat of a mixture of metallic particles and refractory particles in oxygen, the refractory particles were melted by the oxidation reaction heat of the metal particles, since it is a method of fusing the feature unit is simple Have.

Conventional refractory particles, it is common to use a fired refractory particles in order to achieve thermal stability, in Kokoku 5-21865 discloses a refractory granular material at least some, in degrees Kelvin It has been proposed to use what has been previously calcined to a temperature exceeding 0.7 times the indicated melting point. Japanese Patent Application Laid-Open No. 7-237379 proposes the use of silica or a mixture of silica sand and zircon, and Japanese Patent Application Laid-Open No. 2000-159579 proposes the use of a mixture of calcined silica and coached lite.

Further, as the metal particles, it is common to use a mixture of two or more kinds of metal aluminum, Mg—Al alloy, Ca—Si alloy, etc. instead of single metal silicon. For example, Japanese Patent Publication No. 5-21865 uses a mixture of metallic silicon and metallic aluminum, Mg—Al alloy, etc., and Japanese Patent Application Laid-Open No. 2000-159579 discloses metallic silicon with metallic aluminum, Mg—Al alloy, Ca— It has been proposed to use a mixture of Si alloy and the like.
Japanese Patent Publication No. 5-21865 Japanese Patent Laid-Open No. 7-237799 JP 2000-159579 A

  Recent coke ovens have demands such as severer use conditions and longer life of the furnace, and longer life is required than conventional repair materials. In particular, the coking oven carbonization chamber is repeatedly heated and cooled in order to put cold coal powder and steam it into coke.

  By approximating the thermal expansion of silica bricks and repair materials used in coking chambers of coke ovens, it is possible to suppress delamination wear from the brick surface during long-term use, but the material melts and vitrifies immediately after spraying. Therefore, when this crystallizes, it expands, and the expansion reduces the adhesive strength of the brick and the repair material. In order to prevent or suppress this, it was important to crystallize simultaneously with thermal spraying.

The present invention has been made in view of the above points, and in order to solve the above-mentioned problems, a mixture of refractory particles, metal particles, and a crystallization accelerator is sprayed onto a high-temperature repaired object together with oxygen to obtain metal particles. a thermal spray material comprising by welding to the repair material by melting the mixture by oxidation exothermic reaction, with silica or quartz sand refractory particles unfired in 425~2000μm 30-60 wt%, is 75μm or less Less than 10% by weight, 75 to 425 μm is the remainder, the metal particles are metallic silicon, the addition amount is 10 to 30% by weight, 20 to 300 μm is 5 to 50% by weight, and 2 μm or less is 10 ˜40 wt%, 2 to 20 μm being the remainder, crystallization accelerator contains one or more of sodium salt, potassium salt and lithium salt, and the addition amount is 0.3 to 10 wt% Characterized by There is provided a morphism material.

Further, refractory particles, spraying SiO ₂ is characterized in that at least 90 wt%, and an unfired silica or silica sand Al ₂ O ₃ uses 10% by weight of the raw material of the high content of SiO ₂ The material is provided.

Further, the present invention provides a thermal spray material characterized in that the particle size of the refractory particles is 600 μm or more and 10% by weight or less .

Furthermore, the metal silicon particles provide a thermal spray material characterized in that the particle size contains not less than 150 μm and not more than 10% by weight .
Furthermore, a carbon-based powder having an ignition point of 200 ° C. or higher and 800 ° C. or lower is 10% by weight or less, a thermal spray material added as an ignition accelerator, and a silica powder having an average particle size of 0.2 μm or less is 5% by weight. Below, the thermal spray material added as a powder fluidization promoter is provided, respectively.

According to the present invention, the fire- resistant particles are unfired silica stone or silica sand, the metal particles are metal silicon, and the crystallization accelerator is one or more of sodium salt, potassium salt, and lithium salt, so that the brick of the furnace wall The thermal expansion coefficient can be matched, and the refractory particles can be melted to promote crystallization, thereby obtaining a good construction body.

Further, refractory particles, by SiO ₂ is 90 wt% or more, and an unfired silica or silica sand Al ₂ O ₃ uses 10% by weight of the raw material of high SiO ₂ composition, furnace wall brick And a good construction body can be obtained.

And , the particle size of the refractory particles is 4 to 25 to 2000 μm, 30 to 60 wt%, 75 μm or less is 10 wt% or less, and 75 to 425 μm is the rest, so that the material does not pulsate well. Thermal spraying can be performed with little rebound loss.
Since refractory particles having a particle size of 600 μm or more remain as particles and inhibit crystallization of the thermal sprayed body, it is desirable that 600 μm or more is 1% by weight or less.

Moreover, the addition amount of metal silicon particles is 10 to 30% by weight , 20 to 300 μm is 5 to 50% by weight, 2 μm or less is 10 to 40% by weight, and 2 to 20 μm is the remainder. As a result, the refractory particles can be melted with good combustion reaction, and good thermal spraying can be performed.
Since the metal silicon particles having a particle size of 150 μm or more are not preferable because the combustion reaction is weak, the metal silicon particles having a particle size of 150 μm or more can be blended in 10 wt% or less to enhance the combustion reaction.

  Furthermore, the crystallization accelerator is composed of one or more of a sodium salt, a potassium salt, and a lithium salt, and by adding 0.3 to 10% by weight of the crystallization accelerator, the crystallization is promoted and good. A construction body can be obtained.

  Furthermore, by adding a carbon-based powder having an ignition point of 200 ° C. or higher and 800 ° C. or lower as an ignition accelerator at 10% by weight or less, it can be ignited at the start of thermal spraying with good timing and sprayed well as described above. be able to.

  Furthermore, by adding silica powder having an average particle size of 0.2 μm or less as 5% by weight or less as a powder fluidization accelerator, powder fluidization of the thermal spray material can be promoted, and the thermal spraying process can be performed well. Peeled off.

The thermal spray material of the present invention is a thermal spraying method in which a mixture of refractory particles, metal particles, and a crystallization accelerator is sprayed onto a repair target at high temperature together with oxygen, and the mixture is melted by an oxidative exothermic reaction of the metal particles to be welded to the repair target. a material, in silica or quartz sand refractory particles unfired in 425~2000μm 30-60 wt%, in 75μm or less than 10% by weight, is the remainder 75～425Myuemu, metal metal particles Silicon, the addition amount is 10 to 30% by weight, 20 to 300 μm is 5 to 50% by weight, 2 μm or less is 10 to 40% by weight, and 2 to 20 μm is the rest, crystallization accelerator Includes one or more of a sodium salt, a potassium salt, and a lithium salt, and the addition amount is 0.3 to 10% by weight.

Means to be Solved by the Invention

  By adapting the thermal expansion of the thermal spray material with the silica brick on the furnace wall, it is possible to suppress the peeling of the repair brick from the surface by heating and cooling, and to improve the durability. Once melted and vitrified, thermal expansion with silica brick cannot be accommodated. Therefore, as a means for preventing this, it is important to crystallize the repair material simultaneously with the thermal spraying.

The refractory particles, of SiO ₂ is 90 wt% or more, and although Al ₂ O ₃ is characterized by the use of 10 wt% or less of the raw material of high SiO ₂ composition, preferably SiO ₂ is 95 wt% As described above, it is desirable to use a raw material having a high SiO ₂ composition containing 5% by weight or less of Al ₂ O ₃ . When the Al ₂ O ₃ content is 10% by weight or more, crystallization is hindered and the thermal expansion of the furnace wall brick does not match. Examples of the raw material for the refractory particles include unfired silica stone and silica sand.

The particle size of the refractory particles is at 425~2000μm 30-60 wt%, in 75μm or less than 10% by weight, it is desirable 75~425μm is the remainder. When 75 μm or less is 10% by weight or more, pulsation occurs when the material is sprayed, and good spraying cannot be performed. Moreover, since the thing of 600 micrometers or more remains as a particle | grain and inhibits crystallization of a thermal spraying construction body, it is desirable that it is 10 weight% or less. When the amount of 425 μm or more is 60% by weight or more, rebound is large and loss is increased, which is not preferable.

The addition amount of the metal silicon particles is 10 to 30% by weight, and the particle size of the metal silicon particles is 5 to 50% by weight of 20 to 300 μm, 10 to 40% by weight of 2 μm or less, and 2 to 20 μm. The rest is desirable. When the addition amount of the metal silicon particles is 10% by weight or less, the combustion reaction is weak, the refractory particles do not melt, and good thermal spraying cannot be performed. When the added amount is 30% by weight or more, when the material is sprayed, the combustion reaction becomes too strong, the sprayed body flows down, and good spraying cannot be performed.

  In addition, the particle size of the metal silicon particles of 150 μm or more is not preferable because the combustion reaction is weak and should be 10% by weight or less of the metal silicon particles. Even if 20-300 micrometers is 50 weight% or more of a metal silicon particle, a combustion reaction becomes weak and is unpreferable. When 20 to 300 μm is 5% by weight or less of the metal silicon particles, the pulsation increases and good thermal spraying cannot be performed. When the particle size of 2 μm or less is 10% by weight or less of the metal silicon particles, the combustion reaction becomes weak, which is not preferable. Further, when the material of 2 μm or less is 40% by weight or more of the metal silicon particles, when the material is sprayed, the combustion reaction becomes too strong, the sprayed material flows down, and good spraying cannot be performed.

  The crystallization accelerator is characterized by comprising one or more of a sodium salt, a potassium salt and a lithium salt. The addition amount of the crystallization accelerator is preferably 0.3 to 10% by weight. When the amount is less than 0.3% by weight, the effect of promoting crystallization is small. When the amount is more than 10% by weight, the sprayed material flows down during spraying. A good construction body cannot be obtained. Examples of sodium salts include sodium carbonate and sodium chloride, potassium salts include potassium chloride, and lithium salts include lithium carbonate and the like.

  The ignition accelerator is added to the thermal spray material used during thermal spray repair when the temperature of the sprayed body is 900 ° C. or lower. It is characterized by comprising a carbon-based powder having an ignition point of 200 to 800 ° C., and its addition amount is preferably 10% by weight or less as an outer coating. When the ignition point of the ignition accelerator is 800 ° C. or higher, when the wall surface temperature is 900 ° C. or lower, ignition does not occur at the start of spraying. An ignition point of 200 ° C. or lower increases the risk of explosion, which is not preferable for safety.

When the ignition accelerator is metallic aluminum, Al ₂ O ₃ enters the thermal sprayed construction body and inhibits crystallization. Metal magnesium increases the risk of explosion and is not preferable for safety. Carbon-based powders are preferable because they have good combustibility and do not remain in the construction body. If the addition amount is 10% by weight or more as an outer coating, the carbon-based powder remains on the sprayed body, but this is not preferable because it hinders lath formation. Examples of the carbon powder include coke powder and charcoal powder.

  The powder fluidization accelerator is preferably a silica-based powder, and the average particle size is preferably 0.2 μm or less. The addition amount is desirably 5% by weight or less. As shown in FIG. 2 (a), the material was put into the funnel, the stopper rod was pulled out, the vibration 1G was applied, and the discharge time was measured. As a result, as shown in FIG. The effect of promoting fluidization does not increase. It turns out that 2 weight% or less is more preferable. In addition, an alumina system is not preferable because it inhibits crystallization. Metal powder and carbon-based powder having a small average particle size increase the risk of explosion and are not preferable for safety. Examples of the silica-based powder include fumed silica powder.

  Tables 1 and 2 show the test results in the coke oven at A Steel Works. The hot linear expansion coefficient of Example 1, Comparative Example 12, and silica brick is shown in FIG. Example 1 shows a hot linear expansion coefficient equivalent to that of silica brick and is excellent for peeling by heating and cooling. FIG. 2B shows the relationship of the discharge time that is effective as an evaluation of powder fluidity when a powder fluidization accelerator is added to Example 5. As the amount of the powder fluidization accelerator increased, the discharge time was shortened and the fluidity was improved. However, the effect is not further improved at 5% by weight or more. As shown in Table 1, the examples have good discharge properties, ignitability, flammability, adhesion, good thermal spraying workability, and good physical properties of the construction body. Shows life.

Table 1 Example characteristics table

Table 2 Comparative table characteristics

Example and comparative example of the present invention, comparison chart of thermal expansion coefficient of silica brick, Explanatory drawing (a) of the measuring method of the discharge time of a fluid, and the relationship figure (b) of the addition amount of a powder fluidization promoter, and discharge time.

Claims (6)

A spraying material formed by spraying a mixture of refractory particles, metal particles, and a crystallization accelerator together with oxygen onto a high-temperature repair target, melting the mixture by oxidation exothermic reaction of the metal particles, and welding the mixture to the repair target,
In silica or quartz sand refractory particles unfired in 425~2000μm 30-60 wt%, in 75μm or less than 10% by weight, is the remainder 75～425Myuemu,
The metal particles are metallic silicon, the addition amount is 10 to 30% by weight, 20 to 300 μm is 5 to 50% by weight, 2 μm or less is 10 to 40% by weight, and 2 to 20 μm is the remainder,
A thermal spray material, wherein the crystallization accelerator includes one or more of a sodium salt, a potassium salt, and a lithium salt, and an addition amount thereof is 0.3 to 10% by weight. Refractory particles, according to claim 1, SiO ₂ is characterized in that at least 90 wt%, and an unfired silica or silica sand Al ₂ O ₃ uses 10% by weight of a high content of SiO ₂ raw material The thermal spray material as described in.   The thermal spray material according to claim 1 or 2, wherein the particle size of the refractory particles is 600 µm or more and 10 wt% or less.   The thermal spray material according to any one of claims 1 to 3, wherein the metallic silicon particles have a particle size of not less than 150 µm and not more than 10 wt%.   The thermal spray material according to any one of claims 1 to 4, wherein a carbon-based powder having an ignition point of 200 ° C or higher and 800 ° C or lower is added at 10% by weight or less as an ignition accelerator. .   6. The thermal spray material according to claim 1, wherein a silica powder having an average particle size of 0.2 μm or less is added to the thermal spray material according to claim 1 as a powder fluidization promoter at 5% by weight or less. .

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