JP6505797B2 - Thermal spray material - Google Patents

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 for melting refractory powder and welding it to a repair surface (site) by utilizing the oxidation reaction heat of metal powder.

  In industrial kilns, molten metal containers and the like, damage occurs to the lining made of refractory and the like along with its use. For such damage, repair is appropriately performed. For example, many coke ovens at steelworks have been built for more than 20 years, and in particular, the walls of the carbonization chamber continue to operate while being repeatedly repaired.

  There is a thermal spray repair method as a technology for performing repair while continuing the operation. Examples of the thermal spray repair method include plasma thermal spray method, laser thermal spray method, and flame thermal spray method. However, since these thermal spraying methods require a large-scale apparatus, in recent years, a thermal spraying method using an oxidation exothermic reaction of metal, which can be realized by a relatively simple apparatus, is used.

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

  Generally, when repairing a refractory lining, it is preferable that the thermal expansion of the construction body formed by the repair and the repaired refractory be as close as possible. Especially in the kilns such as coke ovens and hot blast furnaces, which continue to operate for several decades without construction after brick relocation, repair materials remain in the construction section for several months to several years to protect the repair section. An effect is required, and therefore, a compact and high-strength construction body is required in which the thermal expansion of the construction body coincides with the portion to be constructed. In most cases, such long-lasting furnaces use silica bricks with a near zero thermal expansion coefficient at 700 ° C. and above, and thus thermal spray that matches or nearly matches that of the silica bricks. Materials are preferred.

  In addition, the thermal spray material needs to exhibit good workability at the time of thermal spray repair. If the workability is poor, the time required for repair will be long, and not only the construction cost will increase, but the construction worker will be exposed to a high temperature and dusty environment for a long time. For the workability of the thermal spray material, for example, easiness of ignition, continuity of combustion, high adhesion rate, less dust generation, etc. are required. Furthermore, due to the characteristics of self-burning and repairing, unexpected explosive combustion (ignition) during construction and a flash fire phenomenon in which the combustion tip propagates backward to the combustion source exposes the worker to danger and a phenomenon occurs. Much time will be spent on maintenance and restoration of the equipment after

  Many 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 diameter of the refractory particles (sillimanite, mullite, zircon, silicon dioxide, zirconium dioxide, aluminum oxide, magnesium oxide, etc.) So that the average particle size distribution ratio of the refractory particles is 1.2 or more, and the average of the particles is larger than the average of 80% and 20% particle sizes of the oxidizing particles (silicon, aluminum, magnesium, zirconium etc.) Disclosed thermal spray materials. According to this thermal spray material, it is believed that the reliability and the fastness can be improved, and a refractory welding layer having high durability can be realized. In addition, by firing at least some of the refractory materials at Kelvin temperature before the temperature exceeds 0.7 times its melting point, the crystalline structure of the refractory material is improved and a high quality sprayed refractory weld layer is obtained. It is believed that it can be formed.

  Patent Document 2 contains a refractory material powder (3 to 30% by mass of magnesia powder, 50 to 90% by mass of siliceous powder) and 5 to 30% by mass of metal Si powder, and the MgO component accounts for the whole composition by the chemical component value. The thermal-sprayed material which made 1-25 mass% is disclosed. Further, Patent Document 3 is a thermal spray material including refractory raw material powder (2 to 25 mass% of calcia powder having CaO content of more than 75 mass%, 50 to 90 mass% of siliceous powder) and 5 to 30 mass% of metallic Si powder. Is disclosed. In these techniques, it is believed that the reaction with magnesia powder and calcia powder promotes the melting of siliceous powder to improve adhesion and adhesion.

  Moreover, patent document 4 is disclosing the thermal spray material containing the refractory powder (The grinding powder of 2000 micrometers or less of a silica brick is a main component) and the metal powder (metallic silicon) which is oxidizing powder. In addition, Patent Document 4 adds 0.3 to 5% by weight of one or more of a sodium salt, a potassium salt, and a lithium salt as a crystallization accelerator to the thermal spray material, and an ignition accelerator As a carbon-based powder (coke powder, charcoal powder, corn starch powder, etc.) or metal powder (iron powder, manganese powder, vanadium powder, etc.) with an ignition point of 300 to 800 ° C. outside the thermal spray material It is disclosed to add ~ 5 wt%. According to this thermal spray material, it is possible to approximate the thermal expansion coefficients of the silica stone brick and the repair material used in the carbonization chamber of the coke oven, so it is possible to suppress peeling and wear from the brick surface during long-term use. ing. In addition, since crystallization can be simultaneously performed with thermal spraying by the addition of a crystallization accelerator, the material can be prevented from crystallization with expansion during use after completion of thermal spraying, and the adhesion strength between the brick and the repair material is lowered. It is said that it can prevent.

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

  By the way, since the coke oven carbonization chamber which is one of the objects to be repaired by the above-mentioned thermal spray material opens and closes the door when extruding coke, the temperature in the furnace between 900 ° C. and 1300 ° C. near the door, for example. Changes. Moreover, when repairing a carbonization chamber, in order to open a door for a long time, temperature in a furnace may fall to about 400 degreeC. If the thermal expansion coefficient of the furnace wall, which is the object to be installed, and the thermal expansion coefficient of the thermal spray coated body used for repair are significantly different at the site exposed to such a large temperature change, the thermal spray coated body is It will peel off from the wall. Therefore, it is necessary to secure the durability by using a thermal spray coated body having a thermal expansion coefficient equal to the thermal expansion coefficient of the furnace wall which is the installation object.

  Moreover, as for the thermal spray material using the oxidation exothermic reaction of metal, the oxide (binder phase) produced | generated by the oxidation of metal powder and the refractory powder partially melted are vitreous. The vitreous substance contained in such a construction body gradually crystallizes during use after the repair construction. Since this crystallization is accompanied by expansion, the construction body peels off from the repair surface of the construction body. Therefore, it is necessary to add a crystallization accelerator and to crystallize it immediately after thermal spraying.

  An alkali metal ion source is added to the thermal spray material to promote crystallization. As such an alkali metal ion source, as disclosed in Patent Document 5, an alkali metal salt which is a safe compound without a risk of explosion or the like and which is easily obtained industrially is used. However, since the alkali metal salt absorbs heat at the time of decomposition, in the repair near the door where the temperature is lowered to about 400 ° C., ignition may be difficult, or the continuation of combustion may be difficult even when the ignition occurs.

  On the other hand, Patent Document 5 uses a combustion aid (metal oxide) that serves as a source of oxygen supply to metal silicon when heat is received, thereby adding no ignition promoter while maintaining durability. Disclosed is a configuration that ensures ignitability and combustion continuity with a small amount of addition.

  Patent Document 6 relates to a powdery mixture of a chemical substance for producing a refractory composition comprising refractory additive particles, metal particles, and metal peroxide-containing particles as a thermal spray material, wherein the metal peroxide-containing particles are An oxide of a base used to form the metal peroxide, and decomposition products of the metal peroxide such as hydroxides and carbonates of the metal, and metal peroxidation Powder-containing particles characterized in that the calcium peroxide content is greater than 0% by weight, at most 75% by weight and / or the magnesium peroxide content is greater than 0% by weight and at most 30% by weight Mixtures are disclosed and these techniques provide step-by-step control of the reaction during thermal spray repair to reduce ignition and flashback.

Japanese Patent Application Laid-Open No. 61-275170 JP, 2006-098029, A Unexamined-Japanese-Patent No. 2006-151771 JP, 2009-120406, A JP 2012-188345 A Patent No. 3946247

  The above-mentioned conventional thermal spray materials do not sufficiently satisfy all of the various properties required of the thermal spray material. That is, when metal silicon is used as the oxidizing particles, the thermal spray material disclosed in Patent Document 1 functions only as the metal silicon as the combustion material, so that the temperature drops to about 400 ° C. as described above. In repair, it is difficult to ignite and there is a possibility that the combustion continuity 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 it is attempted to improve the integrity between the thermal spray layers by the addition of MgO or CaO, sufficient durability can not be ensured when the addition amount is large.

  Further, in the thermal spray material disclosed in Patent Document 4, since the alkali metal salt absorbs heat during decomposition, in the repair of the place where the temperature is lowered to about 400 ° C. as described above, the thermal spray material containing the alkali metal salt causes ignition. It is difficult, or even when ignited, it is difficult to continue combustion. As a result, the adhesion rate of the thermal spray material to the body to be installed is reduced, which causes a problem that the construction efficiency is reduced. In addition, if the combustion of the thermal spray material continues on the surface of the object to be treated and a state in which the binder phase is sufficiently melted can not be realized, there also arises a problem that the integrity between the thermal spray layers becomes poor.

  The thermal spray material disclosed in Patent Document 5 uses the combustion aid (metal oxide) to maintain the durability, and adds no ignition accelerator or adds a small amount of the ignition property and the combustion continuity. It is said that securing, but in the repair of the part which does not need a large amount of buildup such as joint damage, the lance scan speed is made faster because it is necessary to suppress the buildup, but it is likely to be misfired in that case. is there. In the case of a misfire, the lance scanning speed has to be reduced, and the overfilling causes a problem of an uneven finish.

  The thermal spray material disclosed in Patent Document 6 contains metal peroxide-containing particles. The metal peroxide-containing particles contain at most 75% by weight of calcium peroxide and are considered to be extremely high in safety by containing decomposition products such as oxides, hydroxides and carbonates. It is thought that calcium peroxide decomposes at 280 ° C. or higher due to heat reception and releases oxygen, aiming at the auxiliary effect of combustion. However, since calcium peroxide may be classified as a dangerous substance, according to the Hazardous Substance Verification Test Manual, a powder consisting of 60% by weight of calcium peroxide, 20% by weight of calcium hydroxide and 20% by weight of calcium carbonate is used. When we confirmed whether it corresponded to dangerous goods specified in Article 2 Clause 7 of the law, it corresponded to dangerous goods Class 1 Class 1 oxidizing 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 dangerous goods Class 1 Class 1 oxidative solids. In addition to complicated handling at the time of manufacture, it is difficult to say that the safety of first-class oxidizable solid of the first kind of class 1 dangerous solid is safe when it is mixed with the product.

  The present invention has been proposed in view of the above-mentioned conventional circumstances, and can provide a thermal spray material capable of forming a compact construction body whose expansion matches a silica brick, and having excellent workability and safety. The purpose is to

The present invention is premised on a thermal spray material used in a thermal spraying method in which a mixture of a silica-based refractory powder and a metallic silicon powder is used as a main raw material and sprayed with oxygen to repair a surface to be repaired.

  The thermal spray material according to the present invention contains calcium peroxide, and further contains at least one powder 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 It 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.

In addition, a lithium-containing silicate or a lithium-containing silicate mineral can be further added as a crystallization accelerator. In this case, the addition amount is preferably 0.2 to 0.7% by mass in terms of Li ₂ O, externally applied to the total amount of the main raw material. As a lithium containing silicate, lithium silicate can be used, for example. Also, as lithium-containing silicate minerals, for example, spodumene (LiAlSi ₂ O ₆ ), petalite (LiAlSi ₄ O ₁₀ ), eucryptite (LiAlSiO ₃ ), lepidolite (LiKAl ₂ F ₂ Si ₃ O ₉ ), etc. 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, an oxidizable metal powder having the function of assisting the initial heat amount necessary for the oxidation reaction of the metal silicon powder as an ignition promoter is 0.1 to 1.5 mass outside with respect to the total amount of the main raw material %, Can be further blended. As such easily oxidizable metal powder, for example, iron powder, manganese powder, vanadium powder, magnesium powder, titanium powder, powder of an alloy of these, or the like can be suitably used. These metal powders may be used alone or in combination of two or more.

In addition, as a combustion aid, metal oxides having the function of oxidizing the metal silicon powder, which is a combustion agent, are supplied to the installation object by supplying oxygen during combustion of the thermal spray material with respect to the total amount of the main raw material. It can be further blended at 0.3 to 2.0% by mass. As such a metal oxide, for example, transition metal oxides, particularly, first transition metal oxides (scandium oxide, titanium oxide, vanadium oxide, chromium oxide, manganese oxide, iron oxide, cobalt oxide, nickel oxide, oxide) copper) can be suitably used. These metal oxides may be used alone or in combination of two or more.

  According to the present invention, calcium peroxide contained in the thermal spray material reacts with the metal powder by releasing oxygen by decomposition due to heat reception to improve combustion continuity, and CaO after decomposition exhibits a sintering promoting effect . Calcium peroxide is a dangerous substance specified in Article 2 (7) of the Fire Service Act, but it is excluded from dangerous substances by using calcium sulfate or calcium sulfate hydrate as a mixture, so handling at the time of production In addition to ensuring safety when it is contained in the thermal spray material, it also exhibits a sintering promoting effect.

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

  When calcium peroxide or calcium peroxide containing calcium hydroxide is mixed with calcium sulfate anhydride, hemihydrate, monohydrate or dihydrate and tested, it is excluded from dangerous substances The proportion was confirmed. The result of having evaluated whether each mixed powder corresponds to dangerous-goods 1st class in Table 1 is shown. According to the calcium peroxide, when the mixture (sample numbers 10 to 13 and 15 to 20) excluded from the first class of dangerous goods shown in Table 1 is actually added to the thermal spray material and sprayed as shown in the following examples, The effect of improving the flammability and the effect of promoting sintering by the calcium peroxide and the CaO component generated during the decomposition of calcium sulfate were obtained.

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 refractory powder (hereinafter, a mixture of refractory powder and metal powder is referred to as a main raw material), and is further hydroxylated. It 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 additives to control properties. It is added. As described above, calcium peroxide is excluded from dangerous substances by mixing calcium hydroxide and calcium sulfate or calcium sulfate hydrate in a predetermined ratio, and when it is contained in a thermal spray material, combustion continuity is improved and The sintering promoting effect is obtained.

  Calcium peroxide is generally obtained by reacting calcium hydroxide with hydrogen peroxide. Although this reaction product is a mixture of unreacted calcium peroxide and calcium hydroxide, it is possible to add calcium carbonate thereto to reduce the calcium peroxide concentration to 60%, but it is dangerous substance first class 1 It corresponds to a seed oxidizable solid, handling becomes complicated, and it is difficult to say that it is safe for the thermal spray material to contain. On the other hand, when mixed with calcium sulfate or calcium sulfate hydrate having crystal water, it is excluded from dangerous substances, and when it is added to the thermal spray material, the effect of improving the combustion continuity and the effect of promoting sintering are obtained. Was found to be

  Water of crystallization of calcium sulfate hydrate is dehydrated when heated at 120 ° C to 190 ° C, and the effect of endothermic at that time causes the calcium peroxide to be excluded from the hazardous substances class 1 oxidizing solids. It is considered that the calcium peroxide is excluded from the hazardous substance class 1 class 1 oxidizing solid by the addition of calcium sulfate alone, which is the dilution effect of calcium peroxide. Further, it is considered that calcium peroxide is decomposed at the time of combustion to release oxygen, thereby oxidizing unreacted metal silicon powder and improving the combustion continuity. In addition, calcium sulfate dihydrate becomes calcium sulfate after crystal water is released, but calcium sulfate starts to decompose at 1000 ° C or higher, and it is thought that it promotes sintering by forming a solid solution with CaO Be

  The addition amount of calcium sulfate or calcium sulfate hydrate is 45% by mass or more and 73% by mass or less with respect to the whole of the calcium peroxide mixed powder. If it is less than 44% by mass, it is not preferable because it corresponds to a dangerous material. If the content is more than 73% by mass, the combustion continuity and the deposition rate decrease, 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 with respect to the total amount of the main raw material. More preferably, it is 0.7 mass% or more and 1.5 mass% or less.

  If the content of the calcium peroxide mixed powder is less than 0.4% by mass, sufficient effect of improving the combustion continuity can not be obtained, and the CaO component is reduced, so that the sintering effect can not be sufficiently exhibited. On the other hand, when the content is more than 2.6% by mass, it becomes difficult to obtain the intended construction shape by flowing the construction body, and the influence of the construction body composition change becomes strong, and the thermal expansion deviation from the silica stone brick exceeds the allowable range. Furthermore, since the reaction at the time of construction becomes intensely dazzling, the visibility is unfavorably reduced.

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

  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 mainly comprises a mixture of refractory powder and metallic silicon powder. For the refractory powder, silica stone, silica stone brick powder, fused silica, chamotte, cordierite and the like can be used according to 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) based on 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 bounce back during construction, making it difficult to adhere to the workpiece and the thermal spraying efficiency will be reduced.

(Metal powder)
In the thermal spray material according to the present invention, metal silicon powder as a combustion agent is blended. The combustion agent is an oxide that forms a binder phase that combines the above-described refractory powder after combustion. For example, when the target object to be repaired is made of silica brick mainly made of silica, metal silicon powder can be used as the combustion agent.

  The amount of metal silicon powder added is 10 to 25% by mass (10% by mass to 25% by mass), preferably 13 to 17% by mass (13% by mass to 17% by mass) based on the total amount of main raw materials The following is.

  If the addition amount is less than 10% by mass, the combustion reaction is weakened, and the continuity of the combustion and the adhesion to the object to be treated are significantly deteriorated, so that the thermal spray material is not realized. Further, when the addition amount exceeds 25% by mass, the amount of heat generated by the combustion is too much and the temperature becomes too high. As a result, the viscosity of the thermally sprayed material decreases, and the sprayed material flows down from the body to be installed, and a good coated body can not be obtained. The mass ratio (Si purity) of the metal Si component contained in the metal silicon powder is preferably 90% or more. When the Si purity is low, it is not preferable because a large amount of elements such as aluminum which inhibit the crystallization of silica are contained. In addition, the remainder other than the metal silicon powder and the main raw material is a refractory powder.

  The particle diameter of the metal silicon powder is preferably 5 to 75% by mass, 3 to 14% by mass to 20 .mu.m or less, and 20 to 75 .mu.m in the entire thermal spray 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 diameter of 75 μm or more has a weak combustion reaction, and when the compounding amount is large, the combustion continuity is reduced, so the content is preferably 5% by mass or less. Even when the metal powder of 20 μm or less is less than 3% by mass, the combustion reaction is weakened and the combustion continuity is unfavorably reduced. If the metal powder of 20 μm or less exceeds 14% by mass, the powder flowability is lowered to cause pulsation, which is not preferable because the risk of flashback increases.

(Crystallization promoter)
In the thermal spray material according to the present invention, a crystallization accelerator for a lithium-containing silicate (hereinafter referred to as Li-containing silicate) or a lithium-containing silicate mineral (hereinafter referred to as Li-containing silicate mineral) is required. It can be blended according to By adding a suitable amount of crystallization accelerator, it is crystallized immediately after thermal spraying (during cooling of the installation object after repair construction), and exfoliated from the application object of the installation object due to expansion and separation with the application application Can be avoided.

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

The addition amount in the case of adding the crystallization accelerator is 0.2 to 0.7% by mass outside the total amount of the main raw material in terms of oxide (Li ₂ O). If the amount added is less than 0.2% by mass in terms of Li ₂ O, a sufficient crystallization promoting effect can not be obtained. On the other hand, when the addition amount exceeds 0.7% by mass in terms of Li ₂ O, the alkali concentration in the melt becomes high, and the viscosity is lowered to cause the sprayed body to flow, which is not preferable. The particle size of the crystallization accelerator containing Li is not particularly limited, but in order to be rapidly melted and mixed with the binder phase at the time of thermal spraying, it is desirable that the maximum particle size be 1.0 mm or less.

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

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

  It is preferable that the addition amount in the case of adding an ignition promoter is 0.1-1.5 mass% by the outside with respect to the whole quantity of the main raw material. If the addition amount is less than 0.1% by mass, the addition effect (ignition promotion effect) of the ignition promoter can not be obtained sufficiently. On the other hand, if the addition amount is more than 1.5% by mass, the crystallization of the silica is inhibited and the operation hazard such as explosion and flashback is increased, which is not preferable. The particle diameter of the oxidizable metal powder as the ignition promoter is preferably 100 μm or less. If the particle size is larger than 100 μm, the reactivity is poor, and the effect of promoting ignition can not be obtained.

(Combustion aid)
In the thermal spray material according to the present invention, as necessary, a combustion auxiliary agent having a function of oxidizing metal silicon powder, which is a combustion agent, is supplied on the object to be supplied by supplying oxygen during combustion of the thermal spray material. Can. The combustion aid, when attached to metal silicon, is made of metal oxide powder that becomes an oxygen supply source due to heat received when it adheres to a workpiece.

As such a metal oxide, for example, transition metal oxides, particularly, first transition metal oxides (scandium oxide, titanium oxide, vanadium oxide, chromium oxide, manganese oxide, iron oxide, cobalt oxide, nickel oxide, oxide) Copper) can be used suitably. When attached to metal silicon, these metal oxides oxidize metal silicon by reducing their oxidation number during combustion on a target object. Since the metal silicon powder, which is a combustion agent, is oxidized, combustion on the object to be installed is continued. These metal oxides may be added singly or in combination of two or more. From the viewpoint of efficiently oxidizing metal silicon powder, iron oxide (Fe ₂ O ₃ ) is particularly preferable because it has the effect of increasing the oxygen transmission rate when it forms a solid solution in silica glass formed by oxidation of metal silicon powder. It can be used.

  The addition amount in the case of adding a combustion adjuvant is 0.3-2.0 mass% by the outside with respect to the whole quantity of the main raw material. When the addition amount is less than 0.3% by mass, the combustion continuation effect of the combustion agent decreases. Further, when the addition amount is more than 2.0% by mass, the amount of impurities increases, the composition changes too much, and design characteristics such as thermal expansion characteristics can not be exhibited, which is not preferable. The particle diameter of the metal oxide powder is preferably 100 μm or less. If the particle size is larger than 100 μm, the reactivity is poor, and the effect of improving the continuity of combustion can not be obtained.

(Other additives)
In addition to the above-mentioned components, fumed silica, oxides, carbides, nitrides, etc. of elements selected from magnesium, calcium and iron can also be added for the purpose of flowability improvement and adjustment of mineral composition. .

  The thermal spray material of the present invention will be described by presenting examples and comparative examples below.

  Thermal spray materials were prepared at the mixing ratios shown in Table 2 and Table 3, and a construction body formed by thermal spray application using each thermal spray material was evaluated. The refractory powder used in each thermal spray material is silica. The Si purity of the metallic 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 size of the refractory powder and the particle size of the metal silicon powder are shown in Table 2 and Table 3.

  The thermal spraying was carried out by spraying 4 kg of each thermal spraying material onto the body to be sprayed using an ejector-type thermal spraying apparatus. The carrier gas was oxygen with a purity of 100%, and the flow rate was 32 Nm 3 / h. The material supply rate is 95 to 105 kg / h. A lance of 2 m was used, and the tip nozzle diameter was φ14. A 230 × 230 × 30 mm chamotte brick (refractory degree SK36) is placed in a furnace as a material to be sprayed, and the atmosphere temperature in the furnace is heated to about 1000 ° C., then the furnace is opened and the surface temperature of the brick is When the mixture was cooled to about 700.degree. C., a thermal spray application was performed in the form of a pot.

  The evaluation was performed on the ignitability, the combustion continuity, the degree of melting, and the adhesion rate as the thermal spraying workability with respect to the application body by each thermal spray material. Moreover, the thermal expansion coefficient of the construction body was measured as a construction body physical property, and it evaluated about agreement with the thermal expansion coefficient of a silica stone brick. The results of each evaluation are described in Table 2 and Table 3.

  The ignitability was evaluated by visually observing the time until ignition and the combustion state at the start of the thermal spraying application. “◎” indicates ignition within 3 seconds and material starts to adhere, “○” indicates ignition within 6 seconds and material starts to adhere, “△” indicates ignition within 10 seconds It indicates that the material has begun to adhere.

  The combustion continuity was evaluated by visual observation on the combustion continuity at the time of the thermal spray application. “◎” indicates that there is no sign of misfire even if the lance scanning speed is increased, and that combustion continues with strong light at the time of combustion. “○” indicates that there is no sign of misfire and the light at the time of combustion is strong. Continued, but increased lance scan speed indicates that misfire was likely to occur. “△” indicates that there was no sign of misfire and combustion continued while the light at the time of combustion was strong, but misfire would occur if the lance scan speed was slightly reduced Indicates that it has become “●” indicates that there is no sign of misfire even if the lance scanning speed is increased and combustion continues while the light at the time of combustion is strong, but the reaction is too intense to be dazzling and visual recognition becomes difficult It is shown that.

  The degree of melting was evaluated from the appearance during construction and the observation of the cut surface. "○" indicates that the sprayed layer in the construction body was compacted and integrated without sagging during construction, and the discrimination of the layer was unclear, and "」 "did not sag in the construction body but the construction body Indicated that the thermal spray layers were integrated, but that the distinction between the layers was achieved, “x” indicates that the thermal spray layers were not integrated due to insufficient sintering promotion, and “××” indicates melting It indicates that it was dropped during construction due to excess.

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

  The agreement of the thermal expansion with the silica stone brick means that a cylindrical sample is cut out from the construction body in a state where the construction body is cooled, the coefficient of hot linear expansion of the sample is measured, and the coefficient of linear thermal expansion and the silica stone brick The coefficient of thermal expansion 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 problem in practice, and "△" indicates that the deviation is equal to no more than 0.05% and less than 0.10%. Indicated, "x" indicates that there is a concern in practical use, with a deviation of 0.10% or more.

In each of the examples shown in Table 2, the content of the metal silicon powder is 10 to 20% by mass and the content of the calcium peroxide mixed powder in 100% by mass of the main raw material consisting of the refractory powder consisting of silica stone and the metal silicon powder. The amount is 0.4 to 2.6% by mass on the outside, and the content of calcium sulfate or calcium sulfate hydrate in the composition of the mixed calcium peroxide powder is 45 to 73% by mass is there. Further, as additives, spodumene having a particle diameter of 1.0 mm or less as a crystallization accelerator, iron powder having a particle diameter of 100 μm or less as an ignition accelerator, and a second oxide having a particle diameter of 100 μm or less as a combustion aid Iron (iron oxide (III)) powder is added as appropriate. The addition amounts of the spodumene, the iron powder and the ferric oxide powder are specified by the external amount with respect to the whole main raw material. The amount of spodumene is described in oxide (Li 2 _O) conversion. Each composition will be briefly described below.

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

  As shown in Table 2, it can be understood that good results were obtained in all evaluation items of ignitionability, combustion continuity, melting degree, adhesion rate, and matching of thermal expansion with the silica brick.

  Subsequently, a comparative example shown in Table 3 will be described. The comparison example 1 is a combination which does not contain a calcium peroxide mixed powder (composition amount zero) in contrast with the combination of Examples 1 to 4 and Examples 18 to 19. In this composition, the melt became insufficient and the compactness decreased.

  Comparative Examples 2 to 5 are different from Example 3 in that the compounding amount of the calcium peroxide mixed powder is changed. In Comparative Example 2 and Comparative Example 3, the blending amount of the calcium peroxide mixed powder was smaller than the appropriate amount, the melting was insufficient and the compactness was reduced. In addition, Comparative Example 4 and Comparative Example 5 are cases where the compounding amount of the calcium peroxide mixed powder is larger than the appropriate amount, and the construction body looks dazzling and difficult to be recognized at the time of construction and becomes excessively molten and dropped. The expansion of the

  As described above, by forming the thermal spray material with the refractory powder, the metal silicon powder as the combustion agent, and the calcium peroxide mixed powder, a compact applied body whose thermal expansion matches the silica stone brick is formed. Can. 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 goods Class 1 Class 1 oxidation By using the oxygen supply effect of calcium peroxide while avoiding the use of a solid, the combustion continuity is further improved to exert the effect of preventing a misfire even if the lance scanning speed is increased. As a result, the lance scanning speed can be increased in the repair of a portion such as a joint portion that does not require a large amount of build-up, and the workability and the construction quality are improved. As a result, it is possible to suppress an unnecessary long working time and to prevent an increase in construction cost. In addition, the time when the construction worker is exposed to a high temperature dusty environment does not become unnecessary for a long time.

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

Claims (7)

A thermal spray material for use in a thermal spraying method comprising a main raw material comprising a silica-based refractory powder and a metallic silicon powder as a combustion agent, and spraying it with oxygen to repair a surface to be repaired,
0.4 to 2.6 mass% of mixed powder containing calcium peroxide and further containing one or more kinds selected from calcium hydroxide, calcium sulfate and calcium sulfate hydrate relative to the total amount of the main raw material Thermal spray material characterized by being.   Calcium hydroxide in an amount of 25% by mass or more and 44% by mass or less in a mixed powder containing calcium peroxide and further containing one or more selected from calcium hydroxide, calcium sulfate and calcium sulfate hydrate The thermal spray material according to claim 1, containing 0% or more and 11% or less, and containing 45% by mass or more and 73% by mass or less of calcium sulfate or calcium sulfate hydrate. 75 to 90% by mass of the refractory powder with respect to the total amount of the main raw material,
The thermal spray material according to claim 1, wherein the metal silicon powder is contained in an amount of 10 to 25% by mass with respect to the total amount of the main raw material. As a crystallization accelerator, lithium silicate, spodumene (LiAlSi 2 O 6), petalite (LiAlSi 4 O 10), eucryptite (LiAlSiO 3), lepidolite (
The method according to any one of claims 1 to 3, wherein one or more selected from LiKAl2F2Si3O9) is further added in an amount of 0.2 to 0.7% by mass with respect to the total amount of the main raw material. Thermal spray material described in.   One or two or more types selected from iron powder, manganese powder, vanadium powder, magnesium powder, titanium powder, or powder of these alloys as an ignition promoter, as a main raw material by externally attaching to the total amount of the main raw material The thermal spray material according to any one of claims 1 to 4, further comprising 0.1 to 1.5% by mass of   The transition metal oxide according to any one of claims 1 to 5, further comprising 0.3 to 2.0% by mass of a transition metal oxide as a combustion aid, with respect to the total amount of the main raw material. Thermal spray material. It said combustion aid is scandium oxide, titanium oxide, vanadium oxide, chromium oxide, manganese oxide, iron oxide, cobalt, nickel oxide is one or more selected from copper oxide, spraying of claim 6 material.