JP2018062708A - Thermal spray material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal spray material, used for the repair work of an industrial kiln, capable of forming a dense construction body having the same expansion as a silica brick and excellent in workability and safety.SOLUTION: The thermal spray material using a mixture of fire-resistant powder and metal powder as a main raw material and used for a thermal spray method for spraying the thermal spray material with oxygen to repair a surface to be repaired includes calcium peroxide and a mixed powder including one or more kinds selected from a calcium hydroxide, a calcium sulfate and a calcium sulfate hydrate and having the amount of 0.4-2.6 mass% by outer percentage to the total amount of the main raw material. A calcium peroxide of 25-44 mass%, a calcium hydroxide of 0-11% and a calcium sulfate or calcium sulfate hydrate of 45-73 mass% are included in the calcium peroxide mixed powder.EFFECT: The calcium peroxide reacts with the metal powder by discharging oxygen by decomposition due to heat-receiving to improve combustion continuity, and CaO after the decomposition exhibits a sintering promotion effect.SELECTED DRAWING: None

Description

  The present invention relates to a repair material for a furnace wall of an industrial kiln, and more particularly, to a thermal spray material that melts a refractory powder using a heat of oxidation reaction of a metal powder and deposits it on a repair surface (part).

  In industrial kilns, molten metal containers, and the like, damage is caused to the lining made of refractory material with the use thereof. For such damage, repairs are performed as appropriate. For example, many coke ovens in steel works have been in operation for more than 20 years, and in particular, the walls of the carbonization chamber continue to be operated with repeated repairs.

  There is a thermal spray repair method as a technique for performing repairs while continuing operations. Examples of the thermal spray repairing method include a plasma spraying method, a laser spraying method, and a flame spraying method. However, since these spraying methods require a large apparatus, in recent years, a spraying process using a metal oxidation exothermic reaction that can be realized with a relatively simple apparatus has been used.

  For example, Patent Documents 1 to 4 describe a thermal spray material in which a mixture of a metal powder (combustion agent) and a refractory powder is transported with oxygen and sprayed on a high-temperature repair surface in this thermal spraying method. The sprayed mixture forms a refractory composition by an oxidative exothermic reaction of the metal powder caused by heat received from the repair surface and melts and adheres to the repair surface.

  Generally, when repairing a refractory lining, it is preferable that the thermal expansion of the construction body formed by repair and the repaired refractory is closer. Especially in kilns such as coke ovens and hot blast furnaces that have been in operation for several decades without brick replacement after construction, repair materials remain in the construction department for months to years to protect the repair department. An effect is required, and therefore, a construction body having a dense and high-strength structure in which the thermal expansion of the construction body coincides with the work portion is required. In most cases, such furnaces that operate over a long period of time use silica bricks with a coefficient of thermal expansion of approximately zero above 700 ° C., and therefore thermal expansion is equal to or close to that of silica bricks. Material is preferred.

  In addition, the thermal spray material needs to exhibit good workability during thermal spray repair. If workability is poor, the repair takes a long time and not only the construction cost increases, but the construction worker is exposed to a high temperature and dusty environment for a long time. The workability of the thermal spray material is required to be, for example, easy ignition, continuity of combustion, high adhesion rate, and low dust generation. In addition, due to the characteristics of self-combustion and repair, unexpected explosive combustion (ignition) during construction and backfire phenomenon in which the combustion tip propagates backward toward the combustion source puts the worker in danger and causes phenomena After that, a lot of time is spent on maintenance and restoration of the device.

  A number of inventions have been disclosed to satisfy these requirements at a higher level. For example, Patent Document 1 discloses that the particle size of the particles sprayed as a mixture is 80% and 20% of the particle size of refractory particles (sillimanite, mullite, zircon, silicon dioxide, zirconium dioxide, aluminum oxide, magnesium oxide, etc.). Is larger than the average of 80% and 20% particle diameters of oxidizing particles (silicon, aluminum, magnesium, zirconium, etc.), and the particle size distribution range ratio of the refractory particles is 1.2 or more. A thermal spray material is disclosed. According to this thermal spray material, it is said that reliability and fastness can be improved, and a fire-resistant weld layer having high durability can be realized. In addition, by igniting at least some of the refractory material before the temperature exceeds 0.7 times its melting point at the Kelvin temperature, the crystal structure of the refractory material is improved, and a high-quality sprayed refractory weld layer is formed. It can be formed.

  Patent Document 2 includes refractory raw material powder (magnesia powder 3 to 30% by mass, siliceous powder 50 to 90% by mass) and metal Si powder 5 to 30% by mass. The thermal spray material made into 1-25 mass% is disclosed. Further, Patent Document 3 discloses a thermal spray material powder containing refractory raw material powder (calcium powder 2 to 25 mass% of CaO content exceeding 75 mass%, siliceous powder 50 to 90 mass%) and metal Si powder 5 to 30 mass%. Is disclosed. In these techniques, melting of siliceous powder is promoted by reaction with magnesia powder or calcia powder, and adhesion and adhesion are improved.

  Patent Document 4 discloses a thermal spray material containing a refractory powder (a crushed powder of silica brick of 2000 μm or less as a main component) and a metal powder (metal silicon) which is an oxidizable powder. Patent Document 4 discloses that one or more of a sodium salt, a potassium salt, and a lithium salt are added as a crystallization accelerator in an amount of 0.3 to 5% by weight, and an ignition accelerator. As an example, a carbon-based powder (coke powder, charcoal powder, corn starch powder, etc.) or a metal powder (iron powder, manganese powder, vanadium powder, etc.) having an ignition point of 300-800 ° C. The addition of ˜5% by weight is disclosed. According to this thermal spray material, the coefficient of thermal expansion of the silica brick used in the coking chamber of the coke oven and the repair material can be approximated. ing. In addition, since it can be crystallized simultaneously with thermal spraying by adding a crystallization accelerator, it is possible to prevent the material from crystallizing with expansion during use after completion of thermal spraying, and the adhesive strength of bricks and repair materials is reduced. Can be prevented.

  Patent Document 5 discloses that lithium salt is added as a crystallization accelerator to the thermal spray material in an amount of 0.3 to 1.0% by mass in terms of oxide, and metal powder (iron powder, Manganese powder, vanadium powder, etc.) is added to the thermal spray material as an outer coating less than 1.5% by mass, and metal oxides (scandium oxide, titanium oxide, vanadium oxide, chromium oxide, manganese oxide, It discloses that 0.3 to 2.0 mass% of iron oxide, cobalt oxide, nickel oxide, copper oxide) is added as an outer coating to the thermal spray material. According to this thermal spray material, even if an alkali metal salt such as lithium sulfate that absorbs heat during decomposition and lowers the combustion efficiency is added as a crystallization accelerator, it can be ignited without adding a large amount of ignition accelerator. It is said that combustion continuity can be secured safely.

  By the way, since the coke oven carbonization chamber which is one of the repair targets by the above-mentioned sprayed material opens and closes the door when extruding the coke, the temperature inside the furnace is, for example, between 900 ° C. and 1300 ° C. near the door. Fluctuates. In addition, when repairing the carbonization chamber, the door temperature is opened for a long time, so that the furnace temperature may decrease to nearly 400 ° C. In parts exposed to such large temperature fluctuations, if the thermal expansion coefficient of the furnace wall, which is the workpiece, and the thermal expansion coefficient of the thermal spraying construction body used for repair are significantly different, It will be worn away from the wall. Therefore, it is necessary to ensure the durability by using a thermal sprayed construction body having a thermal expansion coefficient equivalent to the thermal expansion coefficient of the furnace wall that is the work body.

  In addition, a thermal spray material using an oxidation exothermic reaction of metal has a vitreous oxide (binding phase) generated by oxidation of metal powder or a partially molten refractory powder. The vitreous contained in such a construction body gradually crystallizes during use after repair construction. Since this crystallization is accompanied by expansion, the construction body is peeled away from the repair surface of the work body. Therefore, it is necessary to add a crystallization accelerator and quickly crystallize after spraying.

  In order to promote crystallization, an alkali metal ion source is added to the thermal spray material. As such an alkali metal ion source, as disclosed in Patent Document 5, an alkali metal salt, which is a safe compound without danger of explosion or the like and easily available industrially, is used. However, since the alkali metal salt absorbs heat at the time of decomposition, it is difficult to ignite by repairing the vicinity of the door whose temperature has dropped to about 400 ° C., or even if it is ignited, it is difficult to continue combustion.

  On the other hand, Patent Document 5 uses a combustion auxiliary agent (metal oxide) that becomes an oxygen supply source to metal silicon when receiving heat, so that no ignition accelerator is added while maintaining durability. The structure which ensures ignition property and combustion continuity with a small amount of addition is disclosed.

  Patent Document 6 discloses a powder mixture of chemical substances for generating a refractory composition composed of refractory additive particles, metal particles, and metal peroxide-containing particles as a thermal spray material. A base oxide used for the production of the metal peroxide and a decomposition product of the metal peroxide, such as a hydroxide and carbonate of the metal, and a metal peroxide Powders characterized in that the product-containing particles have a calcium peroxide content greater than 0% by weight and at most 75% by weight and / or a magnesium peroxide content greater than 0% by weight and at most 30% by weight The mixture is disclosed, and by these techniques, the reaction during the thermal spray repair is controlled step by step to suppress ignition and flashback.

JP 61-275170 A JP 2006-098029 A JP 2006-151771 A JP 2009-120406 A JP 2012-188345 A Patent No. 3946247

  The above-described conventional thermal spray material does not sufficiently satisfy all of the various characteristics required for the thermal spray material. That is, in the thermal spray material disclosed in Patent Document 1, when metal silicon is used as the oxidizing particles, only the metal silicon functions as a combustion material. It is difficult to ignite by repair, and there is a possibility that the continuity of combustion may be insufficient.

  Further, the thermal spray materials disclosed in Patent Document 2 and Patent Document 3 can be expected to improve the integrity between the thermal spray layers, but have a large thermal expansion at 1000 ° C. or higher. Therefore, even if an attempt is made to improve the integrity between the thermal spray layers by adding MgO or CaO, sufficient durability cannot be ensured if the amount added is large.

  In addition, since the thermal spray material disclosed in Patent Document 4 absorbs heat when the alkali metal salt decomposes, in the repair of the portion where the temperature is lowered to about 400 ° C. as described above, the thermal spray material containing the alkali metal salt does not ignite. It may be difficult or it may be difficult to continue combustion even when ignited. As a result, the adhesion rate of the thermal spray material to a construction object falls, and the problem that construction efficiency falls arises. Further, if the sprayed material continues to burn on the surface of the workpiece and the bonded phase cannot be sufficiently melted, there is a problem that the integrity between the sprayed layers becomes poor.

  The thermal spray material disclosed in Patent Document 5 uses a combustion auxiliary agent (metal oxide) to maintain the durability, while adding no ignition accelerator or adding a small amount of ignition accelerator and continuity of combustion. Although it is supposed to be secured, in repairing parts that do not require much overlay such as joint damage parts, it is necessary to suppress overlay, so the lance scanning speed is increased, but in that case it is likely to misfire is there. When a misfire is about to occur, the lance scanning speed must be slowed down, and a problem arises in that the result is an uneven finish due to overfilling.

  The thermal spray material disclosed in Patent Literature 6 includes metal peroxide-containing particles. The metal peroxide-containing particles contain at least 75% by weight of calcium peroxide and contain a decomposition product such as an oxide, hydroxide, carbonate, etc., so that the safety is remarkably high. It is considered that calcium peroxide is decomposed at 280 ° C. or higher by receiving heat and releases oxygen, thereby aiming at an auxiliary effect of combustion. However, since calcium peroxide may fall under the category of dangerous goods, firefighting of powders consisting of 60% by weight calcium peroxide, 20% by weight calcium hydroxide and 20% by weight calcium carbonate in accordance with the Dangerous Goods Identification Test Implementation Manual After confirming whether it falls under the dangerous goods stipulated in Article 2, Paragraph 7 of the Law, it was classified as a dangerous goods class 1 type 1 oxidizable solid. From this, it is considered that the composite particles containing 62% by weight of calcium peroxide as in Example 1 of Document 6 correspond to the hazardous material type 1 type 1 oxidizable solid. Hazardous material type 1 type 1 oxidizable solids are troublesome in handling during production, and it is difficult to say that safety is ensured when mixed in products.

  The present invention has been proposed in view of the above-described conventional circumstances, and can provide a thermal spray material that can form a dense construction body whose expansion matches that of silica brick and is excellent in workability and safety. The purpose is to do.

  The present invention is premised on a thermal spray material used in a thermal spraying method in which a repaired surface is repaired by spraying together with oxygen using a mixture of a refractory powder and a metal silicon powder as a main raw material.

  The thermal spray material according to the present invention includes a mixture of powder containing calcium peroxide and further including one or more selected from calcium hydroxide, calcium sulfate, and calcium sulfate hydrate with respect to the total amount of the main raw material. The thermal spray material contains 0.4 to 2.6% by mass.

  In the calcium peroxide mixed powder, calcium peroxide is 25% by mass or more and 44% by mass or less, calcium hydroxide is 0% or more and 11% or less, and calcium sulfate or calcium sulfate hydrate is 45% by mass or more. Contains 73% by mass or less.

  In the main raw material, the refractory powder may be 75 to 90% by mass with respect to the total amount of the main raw material, and the metal silicon powder may be 10 to 25% by mass with respect to the total amount of the main raw material.

Moreover, a silicate containing lithium or a silicate mineral containing lithium can be further added as a crystallization accelerator. In this case, it is preferable that the addition amount is an outer portion with respect to the total amount of the main raw material and is 0.2 to 0.7% by mass in terms of Li ₂ O. As the lithium-containing silicate, for example, lithium silicate can be used. Further, as lithium-containing silicate mineral, for example, spodumene (LiAlSi ₂ O ₆ ), petalite (LiAlSi ₄ O ₁₀ ), eucryptite (LiAlSiO ₃ ), lipidite (LiKAl ₂ F ₂ Si ₃ O ₉ ) and the like are used. can do. These lithium-containing silicates and lithium-containing silicate minerals may be used alone or in combination of two or more.

  Furthermore, as an ignition accelerator, an easily oxidizable metal powder having a function of assisting the initial heat amount necessary for the oxidation reaction of the metal silicon powder is 0.1 to 1.5 mass on the basis of the total amount of the main raw material. % Can be further blended. As such an easily oxidizable metal powder, for example, iron powder, manganese powder, vanadium powder, magnesium powder, titanium powder, or an alloy powder thereof can be suitably used. These metal powders may be used alone or in combination of two or more.

  In addition, as a combustion aid, a metal oxide having a function of supplying oxygen during combustion of the thermal spray material to oxidize the metal silicon powder as the combustion agent on the workpiece is excluded from the total amount of the main raw material. It can be further blended by 0.3 to 2.0% by mass. Examples of such metal oxides include transition metal oxides, particularly first transition metal oxides (scandium oxide, titanium oxide, vanadium oxide, chromium oxide, manganese oxide, iron oxide, cobalt oxide, nickel oxide, oxidation Copper) and alkaline earth metal peroxides (lithium peroxide, calcium peroxide, magnesium peroxide, strontium peroxide, barium peroxide) can be preferably used. In addition, these metal oxides may be used alone or in combination of two or more.

  According to the present invention, the calcium peroxide contained in the sprayed material reacts with the metal powder by releasing oxygen by decomposition due to heat reception, thereby improving combustion continuity, and the decomposed CaO exhibits a sintering promoting effect. . Calcium peroxide falls under the category of dangerous goods as defined in Article 2, Paragraph 7 of the Fire Service Law. However, by using calcium sulfate or a mixture with calcium sulfate hydrate, it is excluded from dangerous goods. In addition to ensuring safety when contained in the thermal spray material, it also exhibits a sintering promoting effect.

<Confirmation test>
The thermal spray material disclosed in the cited document 6 is added with a metal peroxide such as calcium peroxide in order to oxidize the metal added to the thermal spray material. However, metal peroxides such as the above-mentioned calcium peroxide fall under the category of hazardous material type 1 oxidizable solid. Therefore, by mixing a compound having crystal water, an attempt was made to make it a non-hazardous substance by utilizing the endotherm during dehydration from the crystal water. As the compound having water of crystallization, calcium sulfate which was decomposed at a relatively low temperature of 1000 ° C. to form a solid solution with CaO and expected to have a sintering promoting effect was selected.

  Formulations excluded from hazardous materials when tested by mixing calcium hydroxide containing calcium hydroxide or calcium peroxide with anhydrous, hemihydrate, monohydrate, dihydrate of calcium sulfate The percentage was confirmed. Table 1 shows the results of evaluating whether or not each mixed powder falls under the category of hazardous materials. When the mixture (sample numbers 10 to 13, 15 to 20) excluded from the hazardous material first class shown in Table 1 is actually added to the thermal spray material and sprayed as shown in the following examples, it is caused by calcium peroxide. The effect which improves combustibility and the sintering promotion effect by the CaO component produced | generated at the time of a calcium peroxide and a calcium sulfate decomposition | disassembly were acquired.

<Embodiment>
(principle)
The thermal spray material according to the present invention contains calcium peroxide in a mixture of metal silicon powder as a combustion agent and a refractory powder (hereinafter, a mixture of the refractory powder and the metal powder is referred to as a main raw material), and is further hydroxylated. Contains mixed powder containing at least one selected from calcium, calcium sulfate and calcium sulfate hydrate (hereinafter referred to as calcium peroxide mixed powder), and various trace amounts of additives to control the properties It has been added. As described above, calcium peroxide is excluded from dangerous substances by making a mixture of calcium hydroxide and calcium sulfate or calcium sulfate hydrate in a predetermined ratio. A sintering promoting effect can be obtained.

  Calcium peroxide is generally obtained by reacting calcium hydroxide with hydrogen peroxide. This reaction product is a mixture of unreacted calcium peroxide and calcium hydroxide. However, even if calcium carbonate is added to this mixture to reduce the calcium peroxide concentration to 60%, it is a dangerous substance class 1 first. It is a seed oxidizable solid, handling becomes complicated, and it is difficult to say that it is safe to contain in the thermal spray material. On the other hand, when calcium sulfate or calcium sulfate hydrate with water of crystallization is mixed, it is excluded from dangerous substances, and when added to the thermal spray material, the effect of improving combustion continuity and the effect of promoting sintering are obtained. I found out that

  The water of crystallization of calcium sulfate hydrate dehydrates when heated at 120 to 190 ° C, and due to the endothermic effect at that time, the calcium peroxide is a substance that is excluded from the hazardous substances Class 1 oxidizable solids. It is considered that the addition of calcium sulfate alone excluded the calcium peroxide from the hazardous substance type 1 type 1 oxidizable solid because of the dilution effect of calcium peroxide. In addition, it is considered that calcium peroxide decomposes during combustion and releases oxygen to oxidize unreacted metal silicon powder and improve combustion continuity. Calcium sulfate dihydrate is converted to calcium sulfate after the crystallization water is removed, but calcium sulfate begins to decompose at 1000 ° C or higher, and it is thought that sintering is promoted by forming a solid solution with CaO. It is done.

  The addition amount of calcium sulfate or calcium sulfate hydrate is 45% by mass or more and 73% by mass or less as an inner amount with respect to the whole calcium peroxide mixed powder. If it is less than 44% by mass, it corresponds to a dangerous substance, which is not preferable. If it exceeds 73 mass%, the combustion continuity and the adhesion rate are lowered, which is not preferable. More preferably, it is 50 mass% or more and 60 mass% or less.

  The content of the calcium peroxide mixed powder is 0.4% by mass or more and 2.6% by mass or less based on the total amount of the main raw material. More preferably, it is 0.7 mass% or more and 1.5 mass% or less.

  When the content of the calcium peroxide mixed powder is less than 0.4% by mass, a sufficient combustion continuity improvement effect cannot be obtained, and the CaO component is reduced, so that the sintering effect is not sufficiently exhibited. On the other hand, when the content is more than 2.6% by mass, it becomes difficult to obtain the target construction shape due to the flow of the construction body, and the influence of the construction body composition change becomes strong, and the deviation of thermal expansion from the silica brick exceeds the allowable range. Furthermore, since the reaction at the time of construction becomes intensely dazzling, the visibility is lowered, which is not preferable.

  The particle components of the calcium peroxide mixed powder to be used are calcium peroxide of 25% by mass to 44% by mass, calcium hydroxide of 0% by mass to 11% by mass, and calcium sulfate or calcium sulfate hydrate of 45%. The thing of the mass% or more and 73 mass% or less is preferable. Moreover, it is preferable that a particle size is 200 micrometers or less. This is because if the particle size is larger than 200 μm, the reactivity becomes poor and the effect of improving the combustion continuity tends to be lowered.

  Hereinafter, components other than the calcium peroxide mixed powder will be described in detail.

(Fireproof powder)
As described above, the thermal spray material according to the present invention is mainly composed of a mixture of refractory powder and metal silicon powder. As the refractory powder, silica stone, silica brick powder, fused silica, chamotte, cordierite, or the like can be used depending on the application.

  The refractory powder is 75 to 90 mass% (75 mass% or more and 90 mass% or less), preferably 83 to 87 mass% (83 mass% or more and 87 mass% or less) with respect to the total amount of the main raw material. is there.

  Although not particularly limited, the maximum particle size of the refractory powder is preferably 2.0 mm or less. If the maximum particle size is larger than 2.0 mm, large particles will rebound during construction, making it difficult to adhere to the work piece and lowering the thermal spraying efficiency.

(Metal powder)
In the thermal spray material according to the present invention, metallic silicon powder as a combustion agent is blended. A combustion agent turns into an oxide which forms the binder phase which couple | bonds the above-mentioned refractory powder after combustion. For example, when the work object to be repaired is made of silica brick mainly composed of silica, metal silicon powder can be used as the combusting agent.

  The addition amount of the metal silicon powder is 10 to 25% by mass (10 to 25% by mass), preferably 13 to 17% by mass (13 to 17% by mass) with respect to the total amount of the main raw material. The following).

  If the addition amount is less than 10% by mass, the combustion reaction is weakened, and the continuity of combustion and the adhesion to the workpiece are significantly deteriorated. On the other hand, if the amount added exceeds 25% by mass, the amount of heat generated by combustion is too high and the temperature becomes too high. As a result, since the viscosity of the sprayed material decreases and the sprayed material flows down from the work body and a good work body cannot be obtained, it is not established as a sprayed material. The mass ratio (Si purity) of the metal Si component contained in the metal silicon powder is preferably 90% or more. A low Si purity is not preferable because it contains a large amount of elements such as aluminum that inhibit crystallization of silica. The remainder other than the metal silicon powder of the main raw material is a refractory powder.

  As for the particle diameter of the metal silicon powder, it is preferable that 75 μm or more is 5% by mass or less, 20 μm or less is 3 to 14% by mass, and the remainder is 20 to 75 μm in the entire sprayed material. More preferably, 75 μm or more is 3.0% by mass or less, and 20 μm or less is 5 to 12% by mass. The metal powder having a particle size of 75 μm or more has a weak combustion reaction, and the combustion continuity is lowered when the blending amount is increased. Even when the metal powder of 20 μm or less is less than 3% by mass, the combustion reaction becomes weak and the combustion continuity is lowered, which is not preferable. When the metal powder of 20 μm or less exceeds 14% by mass, the powder fluidity is lowered, causing pulsation and increasing the risk of backfire, which is not preferable.

(Crystallization accelerator)
The thermal spray material according to the present invention requires a crystallization accelerator for lithium-containing silicate (hereinafter referred to as Li-containing silicate) or lithium-containing silicate mineral (hereinafter referred to as Li-containing silicate mineral). It can be blended according to. By adding an appropriate amount of crystallization accelerator, it crystallizes immediately after spraying (during cooling of the work piece after repair work), and peels off the work piece from the work piece due to expansion divergence from the work piece. Can be avoided.

As the Li-containing silicate, for example, lithium silicate can be used. Moreover, as Li-containing silicate minerals, for example, spodumene (LiAlSi ₂ O ₆ ), petalite (LiAlSi ₄ O ₁₀ ), eucryptite (LiAlSiO ₃ ), lipidite (LiKAl ₂ F ₂ Si ₃ O ₉ ), etc. are used. can do. Among these, spojumen and petalite are economically available industrially and are economical. These Li-containing silicates and Li-containing silicate minerals may be used alone or in combination of two or more.

When the crystallization accelerator is added, the amount added is 0.2 to 0.7% by mass in terms of oxide (Li ₂ O), which is an external amount with respect to the total amount of the main raw material. When the addition amount is less than 0.2% by mass in terms of Li ₂ O, a sufficient crystallization promoting effect cannot be obtained. On the other hand, if the amount added exceeds 0.7% by mass in terms of Li ₂ O, the alkali concentration in the melt increases, so that the viscosity decreases and the sprayed material flows down, which is not preferable. The particle size of the crystallization accelerator containing Li is not particularly limited, but it is desirable that the maximum particle size be 1.0 mm or less in order to melt quickly and mix with the binder phase during thermal spraying.

(Ignition accelerator)
In the thermal spray material according to the present invention, an ignition accelerator of an easily oxidizable metal powder having a function of assisting an initial amount of heat necessary for the oxidation reaction of the metal silicon powder can be blended as necessary. By blending the ignition accelerator, it is possible to promote ignition at the start of thermal spraying even when the temperature of the workpiece is a relatively low temperature of 800 ° C. or less.

  As such an easily oxidizable metal powder, for example, iron powder, manganese powder, vanadium powder, magnesium powder, titanium powder, or an alloy powder thereof can be suitably used. These metal powders may be used alone or in combination of two or more. The ignition accelerator can be used if its ignition point is 300 to 800 ° C, but iron powder having an ignition point of 400 ° C or less can be most preferably used.

  When the ignition accelerator is added, the amount added is preferably 0.1 to 1.5% by mass based on the total amount of the main raw material. When the addition amount is less than 0.1% by mass, the effect of adding the ignition accelerator (ignition promotion effect) cannot be obtained sufficiently. On the other hand, when the amount added is more than 1.5% by mass, it is not preferable because it inhibits crystallization of silica and increases the risk of work such as explosion and flashback. The particle size of the oxidizable metal powder as the ignition accelerator is preferably 100 μm or less. This is because if the particle size is larger than 100 μm, the reactivity becomes poor, and the effect of promoting ignition cannot be obtained.

(Combustion aid)
In the thermal spray material according to the present invention, oxygen is supplied during combustion of the thermal spray material, and a combustion auxiliary agent having a function of oxidizing the metal silicon powder as the combustion agent is blended as necessary on the workpiece. Can do. When the combustion auxiliary agent is attached to the metal silicon, the combustion auxiliary agent is made of a metal oxide powder that becomes an oxygen supply source by receiving heat when attached to the workpiece.

Examples of such metal oxides include transition metal oxides, particularly first transition metal oxides (scandium oxide, titanium oxide, vanadium oxide, chromium oxide, manganese oxide, iron oxide, cobalt oxide, nickel oxide, oxidation Copper) can be preferably used. When these metal oxides adhere to the metal silicon, the metal silicon is oxidized by lowering the oxidation number of the metal oxide during combustion on the workpiece. Since the metal silicon powder that is the combustion agent is oxidized, the combustion on the workpiece is continued. These metal oxides may be added alone or in combination of two or more. From the viewpoint of efficiently oxidizing the metal silicon powder, iron oxide (Fe ₂ O ₃ ) is particularly preferable because it has an effect of increasing the oxygen permeation rate when it is dissolved in silica glass formed by oxidation of the metal silicon powder. Can be used.

  When the combustion auxiliary agent is added, the addition amount is 0.3 to 2.0 mass% as an outer shell with respect to the total amount of the main raw material. When the addition amount is less than 0.3% by mass, the combustion continuation effect of the combustor is reduced. On the other hand, when the addition amount is more than 2.0% by mass, impurities are increased and the composition changes so much that design characteristics such as thermal expansion characteristics cannot be exhibited. Moreover, it is preferable that the particle diameter of metal oxide powder is 100 micrometers or less. When the particle size is larger than 100 μm, the reactivity becomes poor and the effect of improving the continuity of combustion cannot be obtained.

(Other additives)
In addition to the above components, fumed silica, oxides of elements selected from magnesium, calcium, and iron, carbides, nitrides, and the like can be added for the purpose of improving fluidity and adjusting mineral composition. .

  Examples and comparative examples are presented below to describe the thermal spray material of the present invention.

  Thermal spray materials were prepared at the blending ratios shown in Tables 2 and 3, and construction bodies formed by thermal spraying using the thermal spray materials were evaluated. The refractory powder used in each spray material is silica. The Si purity of the metal silicon powder used in each thermal spray material is 97%. The composition of the calcium peroxide mixed powder used in each thermal spray material is shown in Tables 2 and 3, and the particle diameter is 125 μm or less. The particle sizes of the refractory powder and the metal silicon powder are shown in Tables 2 and 3.

  The thermal spraying was carried out by spraying 4 kg of each thermal spray material on the sprayed body using an ejector-type thermal spraying apparatus. The carrier gas was oxygen with a purity of 100%, and the flow rate was 32 Nm3 / h. The material supply rate is 95 to 105 kg / h. A lance with a length of 2 m was used, and the tip nozzle diameter was φ14. As a sprayed body, a 230 × 230 × 30 mm chamotte brick (fire resistance SK36) was placed in the furnace, the atmospheric temperature in the furnace was heated to about 1000 ° C., the furnace was opened, and the brick surface temperature Was cooled to about 700 ° C., it was sprayed in a kamaboko shape.

  Evaluation was performed about the ignitability, the combustion continuity, the melting degree, and the adhesion rate as the thermal spraying workability for the construction body by each thermal spray material. Moreover, the thermal expansion coefficient of the construction body was measured as the physical properties of the construction body, and the agreement with the thermal expansion coefficient of the silica brick was evaluated. The results of each evaluation are described in Tables 2 and 3.

  The ignitability was evaluated by visually observing the time to ignite and the combustion state at the start of thermal spraying. “◎” indicates that the material started to ignite within 3 seconds, “○” indicates that the material began to ignite within 6 seconds, and “△” ignited within 10 seconds. This indicates that the material has begun to adhere.

  Combustion continuity was evaluated by visual observation of combustion continuity during thermal spraying. “◎” indicates that even if the lance scanning speed is increased, there is no sign of misfire and combustion continues with strong light during combustion, and “○” indicates that there is no sign of misfire and combustion with strong light during combustion is performed. Although it continued, it showed that it was likely to misfire if the lance scanning speed was increased, and “△” indicates that there was no misfire sign and combustion continued while the light at the time of burning was strong, but if the lance scanning speed was not lowered slightly, it would be misfiring "●" indicates that even if the lance scanning speed was increased, there was no sign of misfire and combustion continued with strong light during combustion, but the reaction was so intense that it became dazzling and difficult to see It is shown that.

  The degree of melting was evaluated from the state during construction and observation of the cut surface. "○" indicates that the sprayed layers in the construction body were dense and integrated without sagging during construction, and the distinction between the layers was unknown. "△" did not sag in the construction body, but the construction body The inside of the thermal spraying layer was integrated, but the interlayer was identified, “×” indicates that the thermal spraying layer was not integrated due to insufficient sintering promotion, and “XX” indicates melting. It indicates that it has dripped during construction due to excessive amount.

  The adhesion rate is obtained by collecting the material adhering to the workpiece after the thermal spray test and measuring the weight, and calculating the ratio of the adhering mass to the weight of the thermal spray material discharged from the tip nozzle.

  The coincidence of thermal expansion with silica brick is that when the construction body is cooled, a cylindrical sample is cut out from the construction body and the hot linear expansion coefficient of the sample is measured. The hot linear expansion coefficient was compared in the range of 400 to 1300 ° C., and the degree of deviation was evaluated. “○” indicates that the deviation is less than 0.05% and there is no practical problem at all, and “△” indicates that the deviation is 0.05% or more and less than 0.10% and that there is no practical problem. "X" indicates that there is a concern about practical problems with a deviation of 0.10% or more.

In each example shown in Table 2, the content of the metal silicon powder is 10 to 20% by mass in 100% by mass of the main raw material consisting of the refractory powder made of silica and the metal silicon powder, and the calcium peroxide mixed powder is contained. The amount is 0.4 to 2.6% by mass as an outer shell, and the content of calcium sulfate or calcium sulfate hydrate in the composition of the calcium peroxide mixed powder is 45 to 73% by mass. is there. Further, as additives, spodumene having a particle size of 1.0 mm or less as a crystallization accelerator, iron powder having a particle size of 100 μm or less as an ignition accelerator, and second oxidized oxide having a particle size of 100 μm or less as a combustion aid. Iron (iron (III) oxide) powder is appropriately added. In addition, the addition amount of spodumene, iron powder, and ferric oxide powder is prescribed | regulated with the outer coating with respect to the main raw material whole quantity. The amount of spodumene is described in oxide (Li 2 _O) conversion. Hereinafter, each formulation will be briefly described.

  In Examples 1 to 4 and Examples 18 to 19, the blending amount of the calcium peroxide mixed powder is changed. Examples 5 to 17 are the composition of Example 3, the amount of spojumen, the amount of ferric oxide powder, the amount of iron powder, the particle size of silica stone, and the composition of the calcium peroxide mixed powder, respectively. It has changed. In Examples 20 to 21, the mixing ratio of the refractory powder and the metal silicon powder is changed in the mixing of Example 3. In Examples 22 to 23, the mixing ratio of the refractory powder and the metal silicon powder in the formulation of Example 19 is changed.

  As shown in Table 2, it can be understood that good results are obtained in each of the evaluation items of ignitability, combustion continuity, degree of melting, adhesion rate, and coincidence of thermal expansion with silica brick.

  Then, the comparative example shown in Table 3 is demonstrated. Comparative Example 1 is a blend that does not contain calcium peroxide mixed powder (zero blending amount) in comparison with the blends of Examples 1 to 4 and Examples 18 to 19. With this formulation, the melt was insufficient and the compactness was reduced.

  Comparative Example 2 to Comparative Example 5 are different from Example 3 in that the amount of the calcium peroxide mixed powder is changed. Comparative Example 2 and Comparative Example 3 were cases where the blending amount of the calcium peroxide mixed powder was less than the appropriate amount, resulting in insufficient melting and reduced compactness. Moreover, Comparative Example 4 and Comparative Example 5 are cases where the blending amount of the calcium peroxide mixed powder is larger than the appropriate amount, and it is dazzling and difficult to see at the time of construction, resulting in a construction body that droops excessively and becomes dripped, and silica brick The expansion of tended to diverge.

  As described above, the thermal spray material is composed of refractory powder, metallic silicon powder as a combustion agent, and calcium peroxide mixed powder to form a dense construction body whose thermal expansion matches that of silica brick. Can do. In addition, by containing calcium peroxide as a mixed powder of calcium hydroxide and calcium sulfate dihydrate or a mixed powder of calcium peroxide and calcium sulfate dihydrate, dangerous substances of the first kind type 1 oxidation By utilizing the oxygen supply effect of calcium peroxide while avoiding the use of porous solids, the effect of preventing misfiring is exhibited even if the lance scanning speed is increased by further improving the combustion continuity. As a result, the lance scanning speed can be increased by repairing parts that do not require much overlay such as joints, and workability and construction quality are improved. As a result, it is possible to prevent the work time from becoming unnecessarily long, and to prevent an increase in construction cost. Further, the time for the construction worker to be exposed to a high temperature and dusty environment is not unnecessarily long.

As described above, the thermal spray material according to the present invention is useful as a thermal spray member used for repairing a coke oven carbonization chamber and the like because it has excellent ignitability and combustion continuity, as well as excellent durability and adhesion.

Claims (7)

A thermal spray material used for a thermal spraying method that includes a main raw material composed of a refractory powder and a metal silicon powder that is a combustion agent, and that is sprayed with oxygen to repair a repaired surface,
Containing 0.4 to 2.6% by mass of mixed powder containing calcium peroxide and containing at least one selected from calcium hydroxide, calcium sulfate, and calcium sulfate hydrate with respect to the total amount of the main raw material Thermal spray material characterized by   In a mixed powder containing calcium peroxide and further containing one or more selected from calcium hydroxide, calcium sulfate, and calcium sulfate hydrate, the calcium peroxide is 25 mass% or more and 44 mass% or less, calcium hydroxide The thermal spray material according to claim 1, wherein 0 to 11% and calcium sulfate or calcium sulfate hydrate is 45% to 73% by mass. 75 to 90% by mass of the refractory powder with respect to the total amount of the main raw material,
The thermal spray material of Claim 1 or Claim 2 containing 10-25 mass% of metal silicon powder with respect to the whole quantity of the said main raw material. As the crystallization accelerator, one selected from lithium silicate, spodumene (LiAlSi ₂ O ₆ ), petalite (LiAlSi ₄ O ₁₀ ), eucryptite (LiAlSiO ₃ ), and lipidoid (LiKAl ₂ F ₂ Si ₃ O ₉ ) The thermal spray material according to any one of claims 1 to 3, wherein two or more kinds are further added in an amount of 0.2 to 0.7% by mass based on the total amount of the main raw material.   As an ignition accelerator, one or two or more selected from iron powder, manganese powder, vanadium powder, magnesium powder, titanium powder, or powders of these alloys are used as the main raw material for the total amount of the main raw material. The thermal spray material according to any one of claims 1 to 4, further added in an amount of 0.1 to 1.5% by mass.   The transition metal oxide is further added as a combustion auxiliary agent in an amount of 0.3 to 2.0% by mass based on the total amount of the main raw material, according to any one of claims 1 to 5. Thermal spray material. The combustion aid is scandium oxide, titanium oxide, vanadium oxide, chromium oxide, manganese oxide, iron oxide, cobalt oxide, nickel oxide, copper oxide, lithium peroxide, calcium peroxide, magnesium peroxide, strontium peroxide, peroxide The thermal spray material of any one of Claims 1-6 which is 1 type, or 2 or more types chosen from barium.