JP2008150235A - Thermal spraying material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To develop a thermal spraying repairing material which fulfills the requirements for increasing severity of using condition and for extending the life of the oven for a long period of time in a coke oven of the recent years and which does not hinder the operation. <P>SOLUTION: The thermal spraying material is one that contains a mixture of refractory particles and metal particles, and that is used by melting the mixture by an oxidation exothermic reaction of the metal particles through spraying the mixture onto a repairing body of a high temperature together with oxygen and by welding onto the repairing body, wherein the refractory particles have a particle size of 2 mm or smaller and contain as a main component a raw material having a composition of 65 wt.% or less SiO<SB>2</SB>and 35-70 wt.% Al<SB>2</SB>O<SB>3</SB>and 1 wt.% or less of an alkali component (Na<SB>2</SB>O, K<SB>2</SB>O), and the metal particles are formed by blending metallic silicon having a particle size of 150 μm or smaller. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a thermal spray material used for repairing these refractory wear parts in the field of thermal spray materials for industrial furnaces and metal melting containers, and due to oxidation exothermic reaction of metal particles contained in the material, refractory particles, low melting point The present invention relates to a thermal spray material that melts particles and welds a repair target.

  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. Thermal spray repair methods include plasma spraying, laser spraying, and flame spraying, but a large-scale apparatus is required.

  On the other hand, there is a method in which refractory particles are melted by heat of oxidation combustion reaction of metal powder such as thermite reaction and welded to the repair surface. This method has a feature that the apparatus is simple because a mixture of metal particles and refractory particles is sprayed on the repair surface heated with oxygen to heat and the refractory particles are melted and welded by heat of oxidation reaction of the metal particles.

  Since the operation downtime, that is, the repair time is limited, when the thermal spray repair of the coking oven carbonization chamber is performed with limited personnel, it may not be possible to take time to clean. In this case, repair work may be interrupted, the door closed, and left for 2 to 6 days. At this time, if the refractory particles of the thermal spray material are silica brick or silica sand, the particles dropped by rebound solidify and it is difficult to clean the bottom of the carbonization chamber furnace. The bottom of the furnace must be cleaned before putting the coal into the carbonization chamber and starting operation.

  Therefore, it is important that the particles that have fallen due to rebound do not solidify even when left at 1000 to 1300 ° C. for about 2 days, and the furnace bottom can be easily cleaned.

In Japanese Patent Publication No. 5-21865, Japanese Patent Laid-Open No. 5-17237, and Japanese Patent Laid-Open No. 2000-159579, since a silica-based refractory material such as silica is used, the rebound material is left at 1000-1300 ° C. for about 2 days. Because it solidifies, the bottom of the furnace cannot be easily cleaned.
Japanese Patent Publication No. 5-21865 JP-A-5-17237 JP 2000-159579

In recent years, coke ovens have demands such as severe use conditions and long life of the furnace, and it is necessary to repair the thermal spraying so as not to hinder the operation. In thermal spraying work, there is always rebound, and it falls and accumulates on the furnace bottom. When silica-based refractory materials such as silica are used, if the rebound material is left at 1000-1300 ° C. for about 2 days, it reacts with the falling metal silicon used for the combustion material, and the refractory falling material solidifies. come. Considering the calorific value and the burned product (SiO ₂ ), metal silicon is the most suitable as the combustion material, and it is difficult to replace it.

  That is, by using metallic silicon as a combustion material, the silica brick of the coke oven carbonization chamber wall is firmly bonded, and the thermal spray itself is also strong. Therefore, it has become necessary to use a material that does not solidify by reacting with falling metal silicon as a refractory material.

The present invention has been made in view of the above points, and in order to solve the above-described problems, a mixture of refractory particles and metal particles is sprayed on a high-temperature repair object together with oxygen, and an oxidation exothermic reaction of the metal particles is performed. A thermal spray material characterized in that a mixture is melted and welded to a repaired object, wherein the refractory particles have a particle diameter of 2 mm or less, SiO ₂ is 65% by weight or less, and Al ₂ O ₃ is 35 to 35%. Thermal spraying characterized in that the raw material has a composition containing 70% by weight, the alkali component (Na ₂ O, K ₂ O) is 1% by weight or less, and the metal particles are metal silicon having a particle size of 150 μm or less. In providing materials.

  The thermal spraying is characterized in that a carbon-based powder or a metal powder or a mixture of a carbon-based powder and a metal powder having an ignition point of 300 ° C. or higher and 800 ° C. or lower is added to the thermal spray material as an ignition accelerator at 5% by weight or less. In providing materials.

  Furthermore, another object of the present invention is to provide a thermal spray material characterized in that an ultrafine silica powder having an average particle size of 0.2 μm or less is added to the thermal spray material as a powder fluidization promoter at 5% by weight or less.

The thermal spray material of the present invention is mainly composed of a raw material having a composition in which the refractory particles have a particle diameter of 2 mm or less, SiO ₂ is 65% by weight or less, and Al ₂ O ₃ is 35 to 70% by weight. Na ₂ O, K ₂ O) is 1% by weight or less, and the metal particles are made of metal silicon having a particle diameter of 150 μm or less, so that the rebound product of the metal particles as the combustion material and the rebound product of the refractory particles are at a high temperature. It can be effectively prevented from sticking and solidifying at (1100 to 1300 ° C.), and it can be well melted by the oxidation combustion heat of the metal particles to prevent rebound, and can be sprayed well.

  In addition, by adding carbon-based powder or metal powder or a mixture of carbon-based powder and metal powder having an ignition point of 300 ° C. or higher and 800 ° C. or lower to the thermal spray material as an ignition accelerator at 5% by weight or less, It can be ignited easily and can be sprayed safely without risk of explosion.

  Further, by adding an ultrafine silica powder having an average particle size of 0.2 μm or less to a thermal spray material as a powder fluidization promoter at 5% by weight or less, the suspension is suspended when the thermal spray material is put into a hopper tank and cut out. Therefore, good thermal spraying can be performed without generating pulsation.

The thermal spray material of the present invention is characterized in that a mixture of refractory particles and metal particles is sprayed onto a repair object at a 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 object. The material is a refractory particle having a particle diameter of 2 mm or less, a raw material having a composition containing SiO ₂ of 65% by weight or less and Al ₂ O ₃ of 35 to 70% by weight, and its alkali component (Na ₂ O, K ₂ O) is 1 wt% or less, and the metal particles are metal silicon having a particle diameter of 150 μm or less.

As shown in FIG. 1, the refractory material has a structure as shown in FIG. 1. A mixture of the refractory material and metal silicon was put in an alumina crucible and fired at 1300 ° C., and it was investigated with a cluster hardness meter whether it solidified hot. As a result, it has been found that solidification is suppressed when the SiO ₂ component of the refractory material is 65% by weight or less and the Al ₂ O ₃ component is 35% by weight or more. Further, since the alkali components _{(Na 2 O, K 2 O} ) comes solidifies to become at least 1% by weight, the alkali content was found necessary to select a refractory material comprising 1 wt% or less.

Table 1 Firing test results (hardness of 20 mm or more solidified)

Therefore, the refractory particles are characterized by using a raw material having a composition of SiO ₂ of 65% by weight or less and Al ₂ O ₃ of 35 to 70% by weight, preferably SiO ₂ of 60% by weight or less. In addition, it is preferable to use a raw material having a composition of 40 to 60% by weight of Al ₂ O ₃ .

When the Al ₂ O ₃ content is 35% by weight or less and the SiO ₂ content is 65% by weight or more, the rebound material of the metallic silicon as the combustion material and the rebound material of the refractory particles are easily welded, and the rebound of the refractory particles. Objects stick together at high temperature (1100-1300 ° C.) and solidify. When Al ₂ O ₃ is 70% by weight or more, the fire resistance exceeds SK37, and it becomes difficult to melt by the oxidation combustion heat of metallic silicon, and rebound increases.

When the alkali components (Na ₂ O, K ₂ O) of the refractory particles are also 1% by weight or more, they tend to solidify, and the alkali component needs to be 1% by weight or less. It is desirable to use pyroxene, mullite, chamotte or the like whose alkali component is 0.5% by weight or less.

  The particle size of the refractory particles is 2 mm or less, 425 μm or more is 10 wt% or less, 425 to 2000 μm is 10 to 60 wt%, 75 μm or less is 10 wt% or less, and 75 to 425 μm is the rest. Is desirable. When 75 μm or less is 10% by weight or more, pulsation occurs when the material is sprayed, and good spraying cannot be performed. 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, the particle size of the metal silicon particles is 150 μm or less, 75 μm or more is 10% by weight or less, 20 μm or less is 5 to 15% by weight, and 20 to 75 μm. Is the rest.

  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.

  When the particle size of the metal silicon particles is 75 μm or more, the combustion reaction is weak and is not preferable, so it must be 10% by weight or less of the metal silicon particles. Even if 20 μm or less is 5 wt% or less of the metal silicon particles, the combustion reaction becomes weak, which is not preferable. When the material is 20% by weight or less and 15% 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 ignition accelerator is added to the thermal spray material when the temperature of the carbonized chamber wall surface is 800 ° C. or less in the thermal spray body, that is, the coke oven. It is characterized by comprising a carbon-based powder or a metal powder having an ignition point of 300 to 600 ° C. or a mixture of a carbon-based powder and a metal powder, and the addition amount is preferably 1 to 5% by weight. When the ignition point of the ignition accelerator is 600 ° C. or higher, when the wall surface temperature is 800 ° C. or lower, it may be difficult to ignite at the start of thermal spraying. If the ignition point is 300 ° C. or lower, the risk of explosion increases, which is not preferable for safety. Moreover, even if the added amount is 5% by weight or more on the outside, the risk of explosion is increased, which is not preferable for safety.

  Examples of the carbon-based powder include coke powder (ignition point: 400 to 600 ° C.), charcoal powder (ignition point: 320 to 400 ° C.), corn starch powder (ignition point: 470 ° C.), and the metal powder is aluminum powder. (Ignition point: 645 ° C), magnesium powder (ignition point: 520 ° C), manganese powder (ignition point: 450 ° C), vanadium powder (ignition point: 500 ° C), iron powder (ignition point: 315-320 ° C), etc. Is mentioned.

  Tables 2 and 3 show the test results of Examples and Comparative Examples of the present invention.

Table 2 Examples and test results

  When adding 10% by weight or more of metal silicon of 75 μm or less, when the thermal spray material is put into the hopper tank and cut out, it cannot be cut out satisfactorily by hanging from the shelf, pulsation occurs, and good thermal spraying cannot be performed. In order to prevent this, a powder fluidization accelerator is added. The powder dough fluidization accelerator is desirably an ultrafine silica powder having an average particle size of 0.2 μm or less, and the addition amount is desirably 5% by weight or less. If it is 5% by weight or more, the effect of promoting fluidization does not increase for a high price.

Table 3 Comparative examples and test results

  Examples 1 to 12 of the present invention have good thermal spraying properties as shown in Table 1, rebounds of metal silicon as a combustion material and rebounds of refractory particles are easily welded, and rebounds of refractory particles Can be prevented from sticking and solidifying at a high temperature (1100 to 1300 ° C.), and can be melted satisfactorily by oxidation combustion heat of metal silicon to prevent rebound, and can be thermally sprayed.

  In addition, Example 5 and Comparative Example 14 were tested for 100 kg each in the A steelworks coke oven, and as a result of examining whether the rebound fallen solidified after 2 days, Example 5 was not solidified, and the furnace bottom was excellent. However, Comparative Example 14 was solidified and difficult to clean.

Explanatory drawing of the solidification test method of the crucible baking of the rebound thing of this invention.

Claims (3)

A spray material characterized by spraying a mixture of refractory particles and metal particles onto a repair object at a high temperature together with oxygen, melting the mixture by oxidation exothermic reaction of the metal particles, and welding the mixture to the repair object,
The refractory particles have a particle diameter of 2 mm or less, a raw material having a composition containing SiO ₂ of 65 wt% or less and Al ₂ O ₃ of 35 to 70 wt% as a main component, and alkali components (Na ₂ O, K _2). A thermal spray material characterized in that O) is 1% by weight or less and the metal particles are metal silicon having a particle size of 150 μm or less.   Adding a carbon-based powder or metal powder or a mixture of a carbon-based powder and a metal powder having an ignition point of 300 ° C. or higher and 800 ° C. or lower, preferably 600 ° C. or lower to the thermal spray material as an ignition accelerator at 5% by weight or less. The thermal spray material according to claim 1, wherein the thermal spray material is a thermal spray material.   The thermal spray material according to claim 1 or 2, wherein an ultrafine silica powder having an average particle size of 0.2 µm or less is added to the thermal spray material as a powder fluidization promoter at 5 wt% or less.

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