JP2000016875A - Maintenance material for flame metal spraying - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a maintenance material for flame metal spraying that has stabilized workability and durability. SOLUTION: This flame metal spraying maintenance material comprises refractory oxide powder and readily oxidizable metallic powder where the refractory oxide powder has a particle size range distribution of <=1.0 with the maximum particle size of <=1.5 mm and the content of fine particles of <=50 μm is <=10 wt.%. In addition, the weight average diameter of the mixture of the refractory oxide powder and the readily oxidizable metallic powder is 300-500 μm and the content of the fine particles of <=20 μm is <=15 wt.% in the mixture.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refractory such as a lining of a kiln and a metal melting furnace, and more particularly to a damaged portion such as joint breaks, cracks, peeling of bricks, abrasion, etc. generated on a wall of a coke oven. The present invention relates to a metal flame spray repair material for repair.

[0002]

2. Description of the Related Art As a thermal spray repairing method, a plasma thermal spraying method and a flame thermal spraying method using a flame such as oxygen-propane are generally known. However, these thermal spraying methods have the disadvantage that the thermal spraying equipment is very large. That point,
The metal flame spraying method utilizing the combustion heat of metal powders such as Al and Si has features that the apparatus is simple and easy to handle.

As a flame spray material, for example, Japanese Patent Publication No. Sho 61
No. 4790 essentially discloses 45 to 70% by weight of SiO _2, 15 to 40% by weight of Al ₂ O ₃ and 1 to 25% of MgO.
A low-expansion flame-sprayed material comprising by weight is disclosed.

Further, Japanese Patent Publication No. Hei 3-9185 discloses that S
iO ₂ from 93.9 to 99.6 _wt%, Al _{2 O} 3 1.5 wt% or less, CaO2.0 wt% or _less, Fe _{2 O} 3 1.0 wt% or less and _Na 2 _O0.4~2 wt% A high siliceous thermal spray material is disclosed. The high-silica spray material disclosed in the publication is intended for use in a flame spraying method, and the particle size is adjusted so that the whole mixed powder has a particle size of 0.21 mm or less. There is a description that it may be used. That is, as in this publication, there are disclosures regarding the particle size of the material constituting the flame sprayed material, but in the flame spraying method and the metal flame spraying method, the specifications of the equipment used and the refractory oxide powder are used. Similar considerations cannot be made due to the large differences in particle size.

On the other hand, with respect to metal flame sprayed materials, for example, Japanese Patent Publication No. 50192/1986 discloses that 5 to 50% of metallic silicon or one or a mixture of two or more alloys containing a silicon component of 55% or more is used. 5 aluminum
A thermal spraying material for repairing a furnace wall, wherein the thermal spraying material contains -20% and the remainder consists of an oxide thermal spraying material.

[0006] Japanese Patent Application Laid-Open No. Hei 3-60472 discloses that
An oxidizing gas and a mixture of refractory and combustion powder are projected onto a surface to burn the fuel and generate sufficient heat to cause the refractory powder to at least partially melt or soften. In a ceramic welding process in which the agglomerates adhere progressively to the surface, the fuel powder is present in a proportion of not more than 15% by weight of the total mixture, and the fuel powder is at least 2% selected from aluminum, magnesium, chromium and zirconium. At least a major part by weight of the refractory powder consists of one or more of magnesia, alumina and chromic oxide, if present, of silica and calcium oxide present in the refractory powder. A ceramic welding method is disclosed in which the molar ratio satisfies the following formula: [SiO ₂ ]% ≦ 0.2 + [CaO]%.

[0007] Further, Japanese Patent Laid-Open No. 4-13308 discloses that
Mixing particles of an exothermic oxidizing material having an average particle diameter of 50 μm or less with particles of a non-combustible refractory material and burning the mixture while spraying the mixture on one surface to form an intimate refractory aggregate on the surface; The oxidizing material comprises silicon and aluminum, wherein aluminum is present in an amount of up to 12% by weight of the total mixture and aluminum and silicon are present in a total amount not exceeding 20% by weight of the total mixture. A method for producing a refractory aggregate is disclosed.

Further, Japanese Patent Publication No. 5-21865 discloses that
Spraying a mixture of refractory granules and oxidizing granules on the surface, causing the oxidizing granules to undergo an exothermic reaction with oxygen and generating sufficient heat to soften or melt at least the surfaces of the refractory granules,
In the refractory molding method in which the refractory is formed on the surface, the average particle size of 80% and 20% of the refractory particles is set to 2.
5 mm or less, the average of the 80% and 20% particle sizes of the oxidizable particles is 50 μm or less, and the particle size range distribution ratio of the refractory particles is 1.2 or more and 1.9 or less. There is disclosed a method for forming a refractory body, wherein the particle size range distribution ratio of the granular material is 1.4 or less.

Further, Japanese Patent Application Laid-Open No. 5-17237 discloses that
A thermal spray material characterized by adding an alloy powder as a heating material to a refractory material is disclosed. Also, JP-A-8-21
No. 0783 discloses a mixed powder comprising one or more refractory oxide powders for repairing a refractory by thermal spraying and one or more oxidizable metal powders which easily form a refractory oxide by burning. And a particle size distribution corresponding to 10% of the cumulative mass fraction of the refractory oxide powder is less than 1.2, and the particle size of the refractory oxide powder is less than 1.2. Disclosed is a flame spray repair material characterized in that the maximum particle size of the easily oxidizable metal powder having a particle size of 5 mm or less is not more than 90% of the integrated mass fraction of the refractory oxide powder. are doing.

Here, it is also disclosed that the particle size range distribution is represented by the following formula:

## EQU1 ## Particle size range distribution ratio f (G) = 2 · (G80−G2
0) / (G80 + G20) where G80 is the 80% by weight particle size of that type of granule, G
20 is the 20% by weight particle size of that type of granules. Among them, the particle diameter corresponding to 10% of the cumulative mass fraction of the refractory oxide powder is 20 to 50% of the cumulative mass fraction of the easily oxidizable metal powder having a particle diameter of 0.5 mm or less. Although it is shown that the diameter is within the range, the amount of the fine powder tends to be large in the refractory oxide powder and the easily oxidizable metal powder as a whole.

[0011]

However, it has not been said that metal flame spraying materials including workability have been sufficiently developed, and the inventors of the present invention have conducted intensive studies and found that metal flame spraying materials have not been sufficiently developed. In the thermal spraying method, it was found that the fluidity of the material had a great effect on the workability, the properties of the sprayed body after the work, and the adhesion rate. That is, if the fluidity of the metal flame sprayed material is poor, the cut-out amount of the material during construction is not stable, and pulsation occurs. for that reason,
Abnormal combustion or flashback occurs when blown out or cut out in large quantities, and there is a risk of clogging of the nozzles and flames passing through the nozzles and burning in the material tank. Further, the thermal sprayed body constructed in such a state has a large density unevenness, and the material is not sufficiently melted, particularly in the portion where the cutout amount is large, the porosity is increased, and the strength of the constructed body is reduced. Further, from the viewpoint of the filling property of the construction body, the particle size distribution of the metal flame sprayed material is very important, and the adhesion rate and the density of the construction body fluctuate depending on the quality of the particle size distribution. However, conventionally, the particle size distribution of the metal flame sprayed material has not been sufficiently studied, particularly the influence of the fine powder portion. Generally, the refractory oxide powder has the particle size obtained by pulverization as it is. I was using. In addition, conventionally, the study of the particle size composition on the density of the sprayed body has not been sufficiently studied. Alloys and the like have been added. However, although the density of the construction body is slightly increased by the addition of these metals, since the metals are highly flammable, the risk of clogging of nozzles due to the occurrence of flashback and the danger of burning in the material tank has been a problem.

Accordingly, it is an object of the present invention to provide a metal flame spray repair material having stable workability and durability.

[0013]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a feature of the present invention is to control the particle size composition of the refractory oxide powder and the easily oxidizable metal powder more than before, and particularly to the fine powder portion. Therefore, it is possible to provide a metal flame spray repair material having stable workability and durability at all times.

That is, the present invention provides a metal flame spray repair material comprising a refractory oxide powder and an easily oxidizable metal powder, wherein the refractory oxide powder has a particle size range distribution ratio of 1.0 or less. The amount of fine powder having a maximum particle size of 1.5 mm or less and 50 μm or less is less than 10% by weight, and the mixture of refractory oxide powder and easily oxidizable metal powder has a weight average diameter of 300 to
The present invention relates to a metal flame spray repair material characterized in that the amount of fine powder having a size of 500 μm and a size of 20 μm or less is 15% by weight or less.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The metal flame sprayed repair material of the present invention comprises a refractory oxide powder and an easily oxidizable metal powder, wherein the refractory oxide powder has a particle size range. The distribution rate is 1.0 or less, the maximum particle size is 1.5 mm or less, and 50 μm.
The amount of the following fine powder is less than 10% by weight. Further, a mixture of the refractory oxide powder and the easily oxidizable metal powder, that is, the amount of fine powder of 20 μm or less in the entire metal flame spray repair material is 15% by weight or less, and the weight average diameter of the mixture is The range is 300 to 500 μm. The easily oxidizable metal powder preferably has a fine powder content of 20 μm or less in an amount of 80% by weight or less. As a result, the fluidity of the flame metal spray repair material is improved, and blow-out, flashback and porosity are suppressed. In addition, since the filling property is good, a dense thermal sprayed product is obtained. For this reason, the addition of highly combustible metal Al or the like, which has been conventionally used to obtain a dense thermal sprayed article, becomes unnecessary.

The present invention will be described in more detail below. First, regarding the refractory oxide powder, if the maximum particle diameter exceeds 1.5 mm, the irregularities on the surface of the sprayed body become large, and at the same time, the rebound loss during the spraying is large. Therefore, the adhesion rate is undesirably reduced. When the amount of the fine powder having a particle size of 50 μm or less is set to less than 10% by weight, if it exceeds 10% by weight, the particle size range distribution rate increases, dust generation becomes remarkable, the adhesion rate decreases, and the fluidity is further deteriorated. Therefore, it is not preferable because flashback occurs and the porosity of the sprayed body is increased.

Here, the “particle size range distribution ratio f (G)” described in the present specification is represented by the following formula:

## EQU2 ## Particle size range distribution ratio f (G) = 2 (80% by weight particle size-20% by weight particle size) / (80% by weight particle size + 20% by weight particle size)

Next, regarding the easily oxidizable metal powder, 20
It is preferable that the amount of fine powder having a particle size of μm or less be 80% by weight or less. This is because the amount of the fine powder having a particle size of 20 μm or less in the mixture of the refractory oxide powder and the easily oxidizable metal powder is suppressed to 15% by weight or less. In addition, 20 μ of the mixture
Fines below m have a significant effect on the fluidity of the mixture.

Here, regarding the fluidity of powder, Carr
Fluidity index [(Sakashita, Introductory Powder Trouble Engineering p24 ~
30 (1986)], and is determined from the values of the densely packed bulk density and the loosely packed bulk density of the powder determined by an ABD powder property measuring instrument as the degree of compression according to the following equation:

## EQU3 ## Compressibility (%) = (closely packed bulk density−loosely packed bulk density) / closely packed bulk density × 100 Here, it is considered that a powder having good fluidity is obtained when the compression degree is 25% or less. .

Therefore, the relationship between the amount of fine powder of 20 μm or less and the degree of compression and workability was examined.
If it exceeds 10% by weight, the degree of compression becomes 25% or more, and pulsation and flashback occur during construction. Further, when adjusting the particle size of the mixture of the refractory oxide powder and the easily oxidizable metal powder to a particle size of 300 to 500 μm, it is 300 μm.
If it is less than m, the number of fine particles is large, and if it exceeds 500 μm, the number of coarse particles is large.
This is because the porosity of the sprayed material tended to increase.

As described above, by using the metal flame spray repair material formulated according to the present invention, there is no blow-out or flashback due to pulsation at the time of construction, and the sprayed body after construction has a high adhesion rate and a low porosity. And a highly durable sprayed body can be obtained. Here, the refractory oxide powder includes silica, chamotte, alumina, spinel, magnesia,
Any one or more of magcro, serpen, petalite, cordierite and the like may be used.

On the other hand, the easily oxidizable metal powder is preferably metal Si, and its addition amount is preferably from 10 to 30% by weight on the outer side. If the amount is less than 10% by weight, stable construction cannot be performed due to incomplete combustion, and the sprayed heat has a low adhesion rate and a high porosity due to low combustion heat. On the other hand, if it exceeds 30% by weight, the fluidity becomes poor, and abnormal combustion and flashback are likely to occur, which is dangerous.

[0023]

EXAMPLES The metal flame sprayed material of the present invention will be further described below with reference to examples. Example 1 A silica powder having a particle size range distribution ratio f (G), a maximum particle size and a fine powder amount of 50 μm or less described in Table 1 was used as a refractory oxide powder. Metallic Si
Was added by an outer hook and the mixture was dry-mixed with a mixer for 20 minutes to prepare metal flame spray repair materials of the present invention and comparative products. Here, as the metal Si, a fine powder having a particle size of 20 μm or less and a constant amount of 70% by weight was used. Next, the degree of compression of the product of the present invention and the comparative product was measured by an ABD powder property measuring device. The obtained degree of compression is also shown in Table 1. Note that the measurement of the degree of compression was measured using AB manufactured by Tsutsui Physical and Chemical Instruments Co., Ltd.
D. Using a powder property measuring instrument, drop the mixed powder into a sample container having an internal volume of 100 ml, fill it, cut it with a stainless steel spatula, weigh it with a balance, and weigh it [loose packing bulk density (g / m
l)] Then, the sample container frame was placed on the loosely filled container, the mixed powder was dropped and filled, and after tapping was performed for 3 minutes, the frame was removed, cut off, and weighed using a balance. This was performed by calculating the degree of compression from the values of the obtained loosely packed bulk density and densely packed bulk density.

Further, 3 kg of the metal flame spray repair material of the present invention and the comparative product was sprayed on a chamotte type brick (230 × 114 mm surface) heated to 600 ° C., and the nozzle clogged due to blowout during the spraying or flashback. At the same time as examining the occurrence or non-occurrence, the adhesion rate of the thermal spray and the apparent porosity were measured for those which did not occur. In addition, the adhesion rate was calculated from the difference between the weight of the chamotte-type normal brick before spraying and the weight of the sprayed body and the chamotte brick after spraying by the following equation:

[Equation 4] Adhesion rate (%) = [weight after thermal spraying (kg) −weight before thermal spraying (kg) / 3 (kg)] × 100 Also, the apparent porosity of the thermal sprayed body is obtained by cutting the thermal sprayed body after cooling, It was measured based on JIS R2205. Table 1 shows the measurement results.

[0025]

[Table 1]

From the measurement results shown in Table 1, the following was found: When the maximum particle size exceeds 1.5 mm, rebound loss increases during thermal spraying, and the adhesion rate decreases. This is considered to be because the larger the particle size, the larger the mass, so that the particles cannot easily adhere and easily rebound. Furthermore, it is also conceivable that, due to the large particle size, melting by heat did not proceed sufficiently, making it difficult to adhere. When the amount of fine powder of 50 μm or less exceeds 10% by weight, the degree of compression increases, and although it does not reach the nozzle clogging due to blowout or flashback, the combustion is unstable and the apparent porosity of the sprayed body is reduced. There is a tendency to be higher. Further, nozzle clogging due to blow-out or flashback occurred due to an increase in the amount of fine powder.
From these points, the maximum particle size of the refractory oxide powder is 1.5.
mm or less, preferably 1.0 to 1.2 mm. Furthermore,
The amount of fine powder of 50 μm or less is 10% by weight or less, preferably 3% by weight.
-5% by weight, and the f (G) value is preferably 0.8-0.9. Here, when the f (G) value is too small, the particle size distribution becomes too narrow, so that the filling property is deteriorated and the apparent porosity increases. On the other hand, the f (G) value is 1.0
If the ratio exceeds, the particle size distribution becomes too wide, so that the filling property is deteriorated and the amount of fine powder is increased, and problems such as flashback easily occur in workability.

Example 2 Next, with respect to Formulation 1 of Example 1, the content and characteristics of metal Si as an easily oxidizable metal powder were investigated. To the same silica powder used for the product 1 of the present invention, metal Si having a different fine powder amount of 20 μm or less was added and dry-mixed with a mixer for 20 minutes to prepare a metal flame spray repair material. Thermal spraying was performed under the same conditions as in Example 1, and the same evaluation was performed. Table 2 shows the evaluation results.

[0028]

[Table 2]

From the measurement results shown in Table 2, the following facts were found: the degree of compressibility was 20 μm or less. As the amount of fine powder increased, the tendency to increase was observed, and the fine powder having a total amount of silica powder and metallic Si of 20 μm or less was observed. 17% by weight (Comparative 2
2; silica powder in 2% by weight), the degree of compression exceeded 25%, and nozzle clogging due to blowout and flashback occurred.

The smaller the amount of fine powder of metal Si of 20 μm or less, the lower the compressibility and the better the fluidity.
The workability at the time of thermal spraying is stabilized without pulsation. However, the apparent porosity of the thermal sprayed body tends to increase, which is considered to be a difference in the burning rate between the fine powder and the coarse powder of metal Si. That is, it is recognized that the fine powder burns at once, whereas the coarse powder burns gradually, so that the particle center remains unburned in the sprayed body. From this fact, it is better that the amount of the metal Si fine powder is large, but if the amount of the fine powder is too large, the fluidity is deteriorated.
The following fine powder amount is 80% by weight or less, preferably 40 to 8%.
0% by weight.

EXAMPLE 3 Metallic Si having a fine powder content of 20 μm or less having a weight of 70 wt% was externally increased to 17 wt%, a maximum particle size of 1.2 mm, and a fine powder having a particle size of 50 μm or less of 5 wt% without being changed. The intermediate particle size was changed, and the mixture was blended so that the weight average diameter of the mixture of silica powder and metal Si was 250 to 600 µm. Silica powder and metal Si were dry-mixed with a mixer for 20 minutes to prepare metal flame spray repair materials of the present invention and comparative products. Each metal flame spray repair material was sprayed under the same conditions as in Example 1 and the same evaluation was performed. Table 3 shows the evaluation results.

[0032]

[Table 3]

From the measurement results shown in Table 3, the following facts were found: no nozzle clogging due to blow-out or flashback occurred, and the workability was all good, but when the weight average diameter was in a range other than 300 to 500 μm. A decrease in the adhesion rate of the thermal spray and the apparent porosity was observed. This is considered to be related to the packing property between the particles, and the weight average diameter is 300 to 5
It is considered that the particles having a size in the range of 00 μm have a particle size composition that facilitates close packing.

[0034]

As described above, in the metal flame spray repairing material used in the metal flame spraying method, the refractory oxide powder and the easily oxidizable metal powder are used after adjusting the particle size, and thus, stable. A dense thermal spray with workability, high adhesion rate and low porosity can be obtained. As a result, the safety of construction is improved as compared with the related art, and the life of a kiln, a molten metal furnace, or the like can be greatly extended by a dense sprayed body.

Claims (2)

[Claims] 1. A metal flame spray repair material comprising a refractory oxide powder and an easily oxidizable metal powder, wherein the refractory oxide powder has a particle size range distribution ratio of 1.0 or less and a maximum particle size Is 1.5
mm or less, and the amount of fine powder of 50 μm or less is less than 10% by weight, and the weight average diameter of the mixture of the refractory oxide powder and the easily oxidizable metal powder is 300 to 500 μm, and the mixture has a particle diameter of 20 μm. A metal flame spray repair material characterized in that the amount of the following fine powder is 15% by weight or less. 2. The metal flame spray repair material according to claim 1, wherein the easily oxidizable metal powder has a fine powder content of 20 μm or less of 80% by weight or less.