JP2016079418A - Thermal spray material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal spray material capable of obtaining ignitability and combustion continuity without adding alkali metal salt and excellent in durability and safety.SOLUTION: A silicate including lithium or a silicate mineral including lithium as a crystallization accelerator are included in a mixture of a fire-resistant powder and a metal powder as a combustion agent. An added amount of a crystallization catalyst is 0.2-0.7 mass% by outer percentage to the total amount of the fire-resistant powder and the metal powder as a combustion agent in terms of an oxide (LiO), and further if needed, an ignition accelerator and a combustion auxiliary agent can be added.SELECTED DRAWING: None

Description

  The present invention relates to a thermal spray material used for repairing an industrial kiln or the like using a metal oxidation exothermic reaction.

  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 steelworks have been built for over 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 repair method include plasma spraying, laser spraying, and flame spraying. However, these spraying methods require a large apparatus. Therefore, in recent years, a thermal spraying method using a metal oxidation exothermic reaction that can be realized with a relatively simple apparatus is also used (for example, see Patent Documents 1 to 3). In this thermal spraying method, a mixture of metal powder (combustion agent) and refractory powder (spraying material) is transported with oxygen and sprayed onto a hot repair surface.

  For example, Patent Document 1 discloses that the particle diameter of particles sprayed as a mixture is 80% and 20% particle diameter of refractory particles (silimanite, 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, and MgO occupies the entire composition in terms of chemical component values. The thermal spray material which made the component 1-25 mass% is disclosed. Furthermore, Patent Document 3 discloses a thermal spray material containing refractory raw material powder (2 to 25 mass% of calcia powder having a CaO content exceeding 75 mass%, 50 to 90 mass% of siliceous powder) and 5 to 30 mass% of metal Si powder. 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.

  On the other hand, the coke oven carbonization chamber, which is one of the objects to be repaired by the above-mentioned sprayed material, opens and closes the door when extruding the coke, so that the furnace temperature is, for example, between 900 ° C. and 1300 ° C. near the door. fluctuate. 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 used for thermal spraying utilizing the oxidation exothermic reaction of a 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.

  As a countermeasure, a technique of adding a crystallization accelerator and crystallizing promptly after spraying is employed. For example, Patent Document 4 discloses a thermal spray material containing a refractory powder (a pulverized powder of silica brick of 2000 μm or less as a main component) and a metal powder (metal silicon) which is an oxidizing powder. Carbon type powder having an ignition point of 300 to 800 ° C. as an ignition accelerator, adding one or more of salt, sodium salt and potassium salt as an external coating to the thermal spray material Coke powder, charcoal powder, corn starch powder, etc.) or metal powder (iron powder, manganese powder, vanadium powder, etc.) is added to the sprayed material in an amount of 0.3 to 5% by weight. 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, so that it is possible to suppress delamination wear from the brick surface during long-term use. 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.

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

JP 61-275170 A JP 2006-098029 A JP 2006-151771 A JP 2009-120406 A JP 2012-188345 A

  In the conventional thermal spray material described above, an alkali metal ion source is added to the thermal spray material in order to promote crystallization. As disclosed in Patent Documents 4 and 5, such an alkali metal ion source is an alkaline chloride, alkali carbonate, sulfuric acid, which is a safe compound without danger of explosion or the like and is easily available industrially. Alkali metal salts such as alkali are used. However, since the alkali metal salt absorbs heat during decomposition, it is difficult to ignite with the sprayed material containing the alkali metal salt in the repair of the vicinity of the door whose temperature has dropped to about 400 ° C., or the combustion continues even when ignited. It may be difficult. On the other hand, Patent Document 5 secures ignitability and combustion continuity by adding a combustion aid made of metal oxide powder. However, the adhesion may decrease under certain conditions, and the effect is not fully satisfactory.

  The present invention has been proposed in view of the above-described conventional circumstances, and provides a thermal spray material that ensures ignitability and combustion continuity without adding an alkali metal salt and is excellent in durability and safety. For the purpose.

  The inventors of the present application first considered a conventional crystallization accelerator. As described above, conventionally, an alkali metal ion source is added to the thermal spray material as a crystallization accelerator. Among alkali metal ions, lithium ions can obtain a high crystallization promoting effect. This is presumably because the ionic radius is small and thus movement within the silica network is likely to occur, and the crystallization promoting effect by cutting the silica network is high.

As such an alkali metal ion source, as disclosed in Patent Document 5, an alkali metal salt that is a safe compound without danger of explosion or the like and is easily available industrially has been used. The salt here is a compound of an anion derived from an acid and a cation derived from a base, but the conventional crystallization accelerator is thermally decomposed at a high temperature, and the cation-derived Li ₂ O remains. On the other hand, the anion derived from the acid was volatilized and diffused. Thus, since the alkali metal salt is decomposed by receiving heat and absorbs heat, in the repair of the vicinity of the door whose temperature has dropped to about 400 ° C., if a thermal spray material containing the alkali metal salt is used, ignition is difficult, Even when ignited, it was difficult to continue combustion.

  On the other hand, in Patent Document 5, ignitability and combustion continuity are improved by using a combination of an ignition accelerator made of metal and a combustion auxiliary agent made of metal oxide. A decrease in the adhesion rate was confirmed due to the endotherm during decomposition of the salt.

From the above considerations, the inventors of the present invention can use Li as a lithium ion source, and if it is a compound that does not cause thermal decomposition, it can be melted by thermal spraying without causing endotherm to act as a lithium ion source. I thought I could do it. As one of such lithium ion sources, attention was focused on silicate minerals containing lithium. Examples of the silicate mineral include spodumene (LiAlSi ₂ O ₆ ) and petalite (LiAlSi ₄ O ₁₀ ).

However, since spodumene and petalite contain aluminum in the composition, there is a concern that Al ₂ O ₃ is generated and the expansion characteristics deviate from the silica brick on the repaired surface, resulting in delamination wear. Therefore, the inventors of the present application actually added spojumen and verified the coincidence between the crystallization promoting effect and the silica brick of thermal expansion characteristics. As a result, it was found that it can be used as a crystallization accelerator and that the adhesion rate is improved as compared with the case where lithium carbonate or lithium sulfate is added. Further, the inventors have found that the crystallization promoting effect is exerted in a smaller amount than the addition amount of the lithium salt (lithium carbonate or lithium sulfate) shown in Patent Document 5 in terms of Li ₂ O.

The inventors of the present application have arrived at the present invention based on the new findings obtained as described above. First. The present invention is premised on a thermal spray material used in a thermal spraying method in which a refractory powder and a metal powder are used as main raw materials and sprayed together with oxygen to repair a repaired surface. The spraying material according to the present invention, addition of a silicate mineral containing silicate or lithium containing lithium to the main raw material, in outer percentage, from 0.2 to 0.7% by mass Li 2 _O in terms It is characterized by that.

  The main raw material may include refractory powder and metal silicon powder. In this case, the refractory powder can be 80 to 90 mass% with respect to the total amount of the main raw material, and the metal silicon powder can be 10 to 20 mass% with respect to the total amount of the main raw material.

  Moreover, 1 type, or 2 or more types chosen from the powder of iron powder, manganese powder, vanadium powder, magnesium powder, titanium powder, or these alloys can also be added as an ignition accelerator. In this case, the addition amount is preferably 0.1 to 1.5% by mass based on the total amount of the main raw material.

  Furthermore, a transition metal oxide can be further added as a combustion aid. In this case, it is preferable that the addition amount is 0.3 to 2.0% by mass with respect to the total amount of the main raw material. In addition, a combustion auxiliary agent can be made into 1 type, or 2 or more types chosen from scandium oxide, titanium oxide, vanadium oxide, chromium oxide, manganese oxide, iron oxide, cobalt oxide, nickel oxide, copper oxide.

  According to the present invention, the silicate containing lithium and the silicate mineral containing lithium added to the main raw material promote crystallization, but combustion by pyrolysis like lithium carbonate or lithium sulfate There is no inhibition. As a result, compared with the case where lithium carbonate or lithium sulfate is added as a crystallization accelerator, the adhesion rate is improved and the operation can be made efficient. In addition, the ignition performance, combustion continuity, durability, and safety are not deteriorated as compared with the prior art.

  The thermal spray material according to the present invention is an additive for controlling the characteristics of a mixture of a refractory powder and a metal powder as a combustion agent (hereinafter, a mixture of the refractory powder and the metal powder is referred to as a main raw material). It is comprised by adding. In the present invention, a silicate containing Li (lithium) (hereinafter referred to as Li-containing silicate) or a silicate mineral containing Li (hereinafter referred to as Li-containing silicate mineral) is added as a crystallization accelerator. Is done. By adding an appropriate amount of Li-containing silicate or Li-containing silicate mineral, a crystallization promoting effect can be obtained. Moreover, when Li containing silicate and Li containing silicate mineral are added as a crystallization accelerator, the adhesion rate improves compared with the case where lithium carbonate or lithium sulfate is added as a crystallization accelerator.

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 ) and the like 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.

The addition amount of the crystallization accelerator is 0.2 to 0.7% by mass (0.2% by mass or more and 0.7% by mass) based on the total amount of the main raw material in terms of oxide (Li ₂ O). % Or less). More preferably, it is 0.24-0.45 mass% (0.24 mass% or more and 0.45 mass% or less). Here, the total amount of the main raw material means a 100% by mass mixture of refractory powder and metal powder.

If the addition amount is less than 0.2% by mass in terms of Li ₂ O, a sufficient crystallization promoting effect cannot be obtained, which is not preferable. 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. Moreover, when the addition amount exceeds 0.7 mass% in terms of Li ₂ O, the thermal expansion coefficient between the sprayed layer and the silica brick on the repaired surface is inevitably contained in the Li-containing silicate. This is not preferable because the divergence of becomes gradually remarkable. 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.

  Hereinafter, components other than the crystallization accelerator will be described in detail.

(Fireproof powder)
As described above, the thermal spray material according to the present invention is configured by adding an additive for controlling characteristics to a mixture of a refractory powder and a metal powder. As the refractory powder, silica stone, silica brick powder, fused silica, chamotte, cordierite, or the like can be used depending on the application.

  Although not particularly limited, the maximum particle size of the refractory powder is preferably 2000 μm. This is because if the maximum particle diameter is larger than 2000 μm, large particles will rebound at the time of 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, a metal 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.

  When the total amount of the mixture of the refractory powder and the metal silicon powder as the main raw material is 100% by mass, the addition amount of the metal silicon powder is 10 to 20% by mass (10 to 20% by mass), preferably Is 13 to 17% by mass (13 to 17% by mass).

  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 20% 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 balance other than the metal silicon powder as the main raw material is refractory powder.

  As for the particle diameter of the metal powder, 75 μm or more is 5% by mass or less, 20 μm or less is 3 to 14% by mass (3% by mass or more and 14% by mass or less), and the remainder is 20 to 75 μm (greater than 20 μm). And 75 μm or less). More preferably, 75 μm or more is 3.0 mass% or less, and 20 μm or less is 5 to 12 mass% (5 mass% or more and 12 mass% or less). 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.

(Ignition accelerator)
In the thermal spray material according to the present invention, an ignition accelerator for metal powder having a function of assisting the 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 a metal powder, for example, iron powder, manganese powder, vanadium powder, magnesium powder, titanium powder, or a powder of these alloys can be preferably used. These metal powders may be added 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 used particularly preferably.

  The addition amount of the ignition accelerator is preferably 0.1 to 1.5% by mass (0.1% by mass to 1.5% by mass) based on the total amount of the main raw material. If the addition amount is less than 0.1% by mass, the effect of adding an ignition accelerator (ignition promoting effect) cannot be obtained sufficiently, which is not preferable. On the other hand, if it is more than 1.5% by mass, the crystallization of silica is hindered, and the risk of work such as explosion and flashback increases, which is not preferable. Moreover, it is preferable that the particle diameter of the metal powder which is an ignition accelerator is 100 micrometers or less. This is because if it is larger than 100 μm, the reactivity becomes poor and it becomes difficult to obtain the effect of accelerating ignition.

(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 material is blended as necessary on the workpiece. Can do. When the combustion auxiliary agent is attached to metal silicon (metal powder) as a combustion agent, 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 metal silicon powder, iron oxide (Fe ₂ O ₃ ) is particularly suitable because it has an effect of increasing the oxygen permeation rate when it is dissolved in silica glass formed by oxidation of metal silicon powder. Can be used for

  The addition amount of the combustion auxiliary agent is 0.3 to 2.0% by mass (0.3% by mass or more and 2.0% by mass or less) based on the total amount of the main raw material. If the amount added is less than 0.3% by mass, the combustion continuation effect of the combustion agent cannot be obtained sufficiently, which is not preferable. 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, which is not preferable. Moreover, it is preferable that the particle diameter of metal oxide powder is 100 micrometers or less. When it 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-mentioned components, for the purpose of reducing the viscosity of SiO ₂ when metallic silicon is melted and improving the integrity between layers during thermal spraying, CaO powder having a purity of 90% or more, MgO having a purity of 90% or more One or more kinds of powders can be added within a range not exceeding 4.0% by mass based on the total amount of the main raw material. When the addition amount exceeds 4.0% by mass, the composition change of the binder phase due to the added CaO powder or MgO powder becomes large, and it is not preferable because the thermal expansion coefficient cannot be matched with the silica brick. Moreover, it is preferable that the particle diameter of CaO powder and MgO powder is 200 micrometers or less. If it exceeds 200 μm, it is difficult to react with silica as a binder phase, and the effect of reducing the viscosity and improving the integrity between the layers cannot be expected.

  In addition, fumed silica and oxides, carbides, nitrides, etc. of elements selected from magnesium, calcium, and iron are added for the purpose of improving fluidity and adjusting the mineral composition within the range not impairing the effects of the present invention. You can also There is no need to add carbonates or sulfates of alkali metals such as lithium for the purpose of promoting crystallization, but if the addition amount is small, the effect on the ignitability, combustion continuity and adhesion of the sprayed material is Since it is small, using together with Li-containing silicate does not necessarily prevent. In this case, the total addition amount of alkali metal carbonate and alkali metal sulfate is less than 0.5% by mass, more preferably less than 0.2% by mass, based on the total amount of the main raw material. It is.

  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 Table 1 and Table 2, and construction bodies formed by thermal spraying using the respective thermal spray materials were evaluated. The refractory powder used in each spray material is silica. Further, the Si purity of the metal silicon powder used in each thermal spray material is 97%. The particle diameter of the refractory powder and the particle diameter of the metal silicon powder are also shown in Tables 1 and 2. In Tables 1 and 2, “1000-2000” means greater than 1000 μm and less than or equal to 2000 μm. “600-1000” means greater than 600 μm and less than 1000 μm. “200-600” means greater than 200 μm and less than or equal to 600 μm. “−200 μm” means 200 μm or less. “75−” means greater than 75 μm. “20-75” means greater than 20 μm and less than or equal to 75 μm. “−20 μm” means 20 μm or less.

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 having 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 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 was 500 When cooled to ˜600 ° C., thermal spraying was performed in a kamaboko shape.

  About the construction body by each thermal spray material, thermal spray workability (ignitability, combustion continuity, adhesion rate), construction body physical properties (coincidence of thermal expansion coefficient with silica brick) were evaluated and listed in Table 1 and Table 2. .

  The ignitability was evaluated by visual observation of the ignitability at the start of thermal spraying. “◎” indicates that the material has started to ignite quickly, “○” indicates that the material has begun to ignite with a slight delay within a range where there is no practical problem, and “△” indicates that the material has ignited. It indicates that the combustion of the object was weak, and “x” indicates that ignition is not performed.

  Combustion continuity was evaluated by visual observation of combustion continuity during thermal spraying. “◎” indicates that there was no misfire sign and combustion continued with strong light during combustion, “○” indicates that there was no sign of misfire but the light during combustion was weak, and “△” indicates misfire. “−” Indicates that evaluation could not be performed because ignition was not performed at the start of spraying.

  The adhesion rate is obtained by collecting the material adhering to the sprayed object after the thermal spray test, measuring the weight, and calculating the ratio of the adhering mass to the weight of the thermal spray material discharged from the tip nozzle. "-" Indicates that the evaluation could not be performed because ignition was not performed at the start of spraying or misfiring.

  The coincidence of thermal expansion coefficient 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, and the hot linear expansion coefficient and the quartz brick are measured. Were compared in the range of 400 to 1300 ° C., and evaluated by the degree of divergence at 1300 ° C. when 600 ° C. was the starting point. “◎” indicates that the deviation is 0.03% or less, “○” indicates that the deviation is greater than 0.03% and 0.15% or less, and “×” is greater than 0.15%. “−” Indicates that the construction body was not obtained and could not be evaluated because the ignition was not ignited or misfired. Note that “、” and “◯” are coincident to the extent that there is no practical problem.

In each example shown in Table 1, the content of the metal silicon powder is 10 to 20% by mass in the main raw material 100% by mass composed of the refractory powder made of silica and the metal silicon powder, and further, as a crystallization accelerator, It is a blend in which Li-containing silicate or Li-containing silicate mineral is added in an amount of 0.2 to 0.7% by mass in terms of Li ₂ O conversion. As the crystallization accelerator, spodumene, petalite, lithium silicate, cryptite, and lipidoid having a particle size of 1000 μm or less are used alone or in combination. For the purpose of improving interlaminar integrity, calcium oxide powder (CaO purity is 95%) having a particle size of 75 μm or less is added. Further, iron powder having a particle size of 100 μm or less as an ignition accelerator and ferric oxide (iron (III) oxide) powder having a particle size of 100 μm or less are appropriately added as a combustion aid. In addition, the addition amount of a calcium oxide powder, iron powder, and ferric oxide powder is prescribed | regulated by the outer coating with respect to the main raw material whole quantity. Hereinafter, each formulation will be briefly described.

Examples 1 to 4 are blends in which spodomen is added as a crystallization accelerator, and the blending amounts thereof are changed. Examples 5 to 8 are blends to which petalite is added as a crystallization accelerator, and the blending amounts thereof are changed. Examples 9 to 11 are blends to which lithium silicate, corcryptite, and lipidoid are added as crystallization accelerators, respectively, and the blending amounts thereof are those in Example 2 and Example 6 in terms of Li ₂ O. It is equivalent. Examples 12 to 15 are blends to which spojumen and petalite are added as crystallization accelerators, and the total blend amounts thereof are changed. In Example 16, in the formulation of Example 2, the silica particle size formulation is changed. In Examples 17 to 19, the amounts of iron powder and ferric oxide in the formulation of Example 2 are changed. In Examples 20 to 22, the mixing ratio of the refractory powder, which is the main raw material, and the metal silicon powder in the formulation of Example 2 is changed.

  As shown in Table 1, it can be understood that in all of the Examples, good results were obtained in each evaluation item of ignitability, combustion continuity, adhesion rate, and coincidence of thermal expansion with silica brick. In addition, in each example, a result in which the adhesion rate was improved was obtained even when compared with the case where lithium carbonate or lithium sulfate was used (for example, see Comparative Examples 3 to 6 described later). .

  Subsequently, a comparative example will be described. In Comparative Example 1 and Comparative Example 2, the amount of spojumen used as a crystallization accelerator in the formulations of Examples 1 to 4 is changed. In Comparative Example 1, the amount was less than the appropriate amount, and there was a disagreement in the evaluation items for the coincidence of thermal expansion with the silica brick. Comparative Example 2 was a case where the amount was larger than the appropriate amount. As a result of the increase in the alkali concentration in the melt, the viscosity decreased, and the sprayed material flowed down, the adhesion rate decreased. Also, the thermal expansion coefficient mismatch tended to be slightly larger.

Comparative Example 3 to Comparative Example 6 are lithium sulfate in place of Li-containing silicate or Li-containing silicate mineral as a crystallization accelerator in the formulations of Examples 1 to 15 and Examples 17 to 19.・ It is a formulation with added monohydrate. The addition amount of lithium sulfate monohydrate is 0.47% by mass (2.0% by mass for lithium sulfate) as an outer cover in terms of Li ₂ O with respect to the total amount of the main raw material. Moreover, in each comparative example, the addition amount of iron powder and ferric oxide is changed.

  Comparative Example 3 is similar to the blending of Examples 1 to 16, except that 0.8% by mass of iron powder and ferric oxide are added as outer shells with respect to the total amount of the main raw material. The continuity of combustion decreased and the adhesion rate also decreased. In Comparative Example 4, as with the formulation of Example 17, only iron powder was added in an amount of 1.0% by mass based on the total amount of the main raw material, but the combustion continuity was further reduced as compared with Comparative Example 3. did. In Comparative Example 5, as in the formulation of Example 18, only ferric oxide was added in an amount of 1.5% by mass based on the total amount of the main raw material. Declined. Comparative Example 6 was a formulation in which neither iron powder nor ferric oxide was added as in the formulation of Example 19, but ignition was not performed at the start of thermal spraying.

  From the above results, by adding an appropriate amount of Li-containing silicate or Li-containing silicate mineral as a crystallization accelerator to refractory powder and metal silicon powder, it has excellent ignitability and combustion continuity, durability and safety A thermal spray material with excellent properties can be realized. In addition, the adhesion rate is improved as compared with the conventional formulation using lithium carbonate or lithium sulfate, and an excellent effect can be obtained by adding a smaller amount. Further, as can be understood from Example 19, a sprayed material having no problem in ignitability and combustion continuity can be realized even if the formulation does not include an ignition accelerator and a combustion auxiliary agent.

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

Claims (5)

It is a thermal spray material used in a thermal spraying method in which refractory powder and metal powder are used as main raw materials and sprayed with oxygen to repair the repaired surface.
Spray material to a silicate mineral containing silicate or lithium containing lithium to the main raw material, in outer percentage, characterized in that the addition from 0.2 to 0.7% by mass Li 2 _O conversion. The main raw material includes refractory powder and metal silicon powder,
The refractory powder is 80 to 90% by mass with respect to the total amount of the main raw material,
10-20% by mass of metal silicon powder with respect to the total amount of the main raw material
The thermal spray material according to claim 1, wherein   As an ignition accelerator, one or more selected from iron powder, manganese powder, vanadium powder, magnesium powder, titanium powder, or a powder of an alloy thereof is 0.1% as an outer shell with respect to the total amount of the main raw material. The thermal spray material of Claim 1 or Claim 2 which added -1.5 mass% further.   The transition metal oxide as a combustion auxiliary agent is further added 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 3. Thermal spray material.   The said combustion auxiliary agent is 1 type, or 2 or more types chosen from scandium oxide, titanium oxide, vanadium oxide, chromium oxide, manganese oxide, iron oxide, cobalt oxide, nickel oxide, and copper oxide of Claim 4. Thermal spray material.