WO2017043423A1 - Sealing agent, sealing agent coating solution, corrosion-resistant coating film, high-temperature member, and method for producing high-temperature member - Google Patents

Abstract

Provided is a sealing agent that does not corrode substrates. A sealing agent for sealing the pores of a corrosion-resistant coating film, the sealing agent characterized in comprising glass having a proportion of alkali metal oxide in the composition of 20 mass% or less.

Description

Sealant, sealant coating solution, corrosion-resistant coating, high temperature member and method for producing high temperature member

The present invention relates to a sealing agent for filling pores of a corrosion-resistant film, and a corrosion-resistant film and a high-temperature member produced using the same.

In thermal power generation, coal, oil, and LNG are burned in a boiler, and the turbine is rotated using the high-temperature and high-pressure gas, or the turbine is rotated by steam generated using the heat of the high-temperature gas. Is going. For this reason, high temperature members such as gas turbines and heat transfer tubes are exposed to corrosive and oxidizing combustion gas atmospheres of oxygen, sulfur oxides, hydrogen sulfide, etc. at 500 to 1000 ° C. As a result, there is a problem of a decrease in life due to so-called high temperature corrosion.

Since the high temperature member deteriorates due to such acid gas corrosion, it is necessary to frequently replace the high temperature member. Since replacement of the high temperature member increases the power generation cost, a high temperature member that does not deteriorate for a longer period of time is required.

Therefore, it has been studied to prevent the deterioration by forming a corrosion-resistant film on the surface of these high-temperature members. In order to extend the life of the high-temperature member by the corrosion-resistant coating, it is important how to form a dense coating without pores. That is, if pores exist in the corrosion-resistant film, the acidic gas reaches the base material of the high temperature member through the pores, and the high temperature member is corroded.

JP 2001-152307 A JP-A-60-194063

For example, Patent Document 1 discloses a composite coating in which cermet or ceramics is formed by thermal spraying as a base layer, a sealing process is performed on the surface of the base layer with an oxide ceramic, and a glassy coating is further formed. The composite coating described in Patent Document 1 has no through pores and exhibits not only excellent corrosion resistance against corrosive gas, but also the service life of the substrate is remarkably improved. Examples of sealing agents include heat-resistant organic resin ceramic suspensions, chromic acid that generates Cr ₂ O ₃ by heating, inorganic metal compound solutions and colloidal solutions that generate metal oxides by firing, metal alkoxide alcohol solutions Metal chloride aqueous solution or alcohol solution, metal phosphate aqueous solution, metal hydroxide colloid solution, alcohol or water suspension containing metal oxide ultrafine powder, or a mixture of two or more of these are recommended . However, these sealing agents have a problem that gas is generated even after solidification and complete sealing cannot be performed. Moreover, although the use of Na ₂ SiO ₃ , NaPO ₃ , NaHSiO ₃ as an inorganic binder has been proposed, these include alkali metals. As described in Patent Document 2, since alkali metals cause high-temperature corrosion, if the above-described inorganic binder is used, these may corrode a base material or a coating film.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a sealing agent that does not corrode the base material.

The sealing agent of the present invention is a sealing agent for sealing pores of a corrosion-resistant film, and is characterized by comprising glass having a proportion of alkali metal oxide in the composition of 20% by mass or less. Here, the “alkali metal oxide” refers to one or more of Li ₂ O, Na ₂ O, and K ₂ O.

The sealing agent having the above configuration does not corrode the base material because it has few alkali metal components.

In the present invention, it is preferably made of glass containing ZnO and / or B ₂ O ₃ as an essential component.

In addition to the above problems, it is desirable that the sealing agent can seal the pores of the corrosion-resistant film over a long period of time. In response to this problem, the present inventors have found that amorphous glass or crystalline glass having a low softening point may be adopted as the glass constituting the sealing agent.

The sealing agent of the present invention that can seal the pores of the corrosion-resistant film for a long period of time is a sealing agent for sealing the pores of the corrosion-resistant film, and has a softening point of 900 ° C. or less and an alkali metal occupying the composition It is characterized by comprising an amorphous glass having an oxide ratio of 20% by mass or less. “Amorphous glass” means glass having a property that crystals do not precipitate when heat-treated at a softening point of + 40 ° C. for 30 minutes.

Since the sealing agent having the above-described structure is made of glass having a low softening point, when the high temperature member is exposed to a high temperature, the sealing agent enters a molten state and flows to fill the pores. Can be sealed. Moreover, since there are few alkali metal components, a base material is not corroded.

By the way, when the thermal power generation facility temporarily stops operation, for example, by repair or the like, and the high temperature member is cooled, the sealing agent may be cracked due to a difference in expansion from the high temperature member or the like. Even when such a situation occurs, the sealing agent of the present invention is made of amorphous glass. Therefore, when the equipment is restarted and the high temperature member is exposed to a high temperature, the sealing agent is restarted. Melt. As a result, since the crack of the sealing agent disappears, it can be returned to the sealing state again.

In the present invention, the amorphous glass has a glass composition of B ₂ O ₃ 10 to 50%, ZnO 0 to 70%, MgO + CaO + SrO + BaO 0 to 80%, Li ₂ O + Na ₂ O + K ₂ O 0 to 20% as a glass composition. SiO ₂ 0-50% and Al ₂ O ₃ 0-30% are preferable. Here, “MgO + CaO + SrO + BaO” means the total amount of MgO, CaO, SrO and BaO. “Li ₂ O + Na ₂ O + K ₂ O” means the total amount of Li ₂ O, Na ₂ O and K ₂ O.

If the above configuration is adopted, it becomes easy to produce a sealing agent that is amorphous and has a low softening point.

In the present invention, the amorphous glass is preferably B ₂ O ₃ —ZnO-based glass. Here, “B ₂ O ₃ —ZnO-based glass” refers to glass containing 10% by mass or more of B ₂ O ₃ and 1% by mass or more of ZnO as a glass composition.

Another sealing agent of the present invention that can seal pores of the corrosion-resistant coating over a long period of time is a sealing agent for sealing pores of the corrosion-resistant coating, and the proportion of the alkali metal oxide in the composition is It consists of crystalline glass which is 20 mass% or less. In the present invention, “crystalline glass” means glass having a property that crystals are precipitated when heat-treated at a softening point of + 40 ° C. for 30 minutes.

In the sealing agent having the above structure, crystals are precipitated from the glass when the high temperature member is exposed to a high temperature (operating temperature range). Since the crystal is less reactive than the amorphous glass, the sealing agent of the present invention in which the crystal is precipitated has a feature that it hardly reacts with a high-temperature combustion gas. Moreover, since there are few alkali metal components, a base material is not corroded.

In the present invention, the crystalline glass has a glass composition as a percentage by weight of ZnO 10-80%, B ₂ O ₃ 0-50%, MgO + CaO + SrO + BaO 0-50%, Li ₂ O + Na ₂ O + K ₂ O 0-20%, It is preferable to contain 0 to 50% of SiO _{2 and} 0 to 30% of Al ₂ O ₃ .

If the above configuration is adopted, it becomes easy to produce a sealing agent made of crystalline glass.

In the present invention, the crystalline glass is preferably ZnO—B ₂ O ₃ glass. Here, “ZnO—B ₂ O ₃ -based glass” refers to glass containing 10% by mass or more of ZnO and 1% by mass or more of B ₂ O ₃ as a glass composition.

The sealant coating solution of the present invention is characterized by containing the above-mentioned sealant.

If the above configuration is adopted, it becomes easy to apply the sealing agent on the corrosion-resistant coating by a simple method such as brushing.

The corrosion-resistant film of the present invention is a corrosion-resistant film containing 50% by mass or more of at least one selected from ZrO ₂ , Al ₂ O ₃ and SiO _2, and the powder composed of the above-mentioned sealing agent is attached to the surface. It is characterized by that. “Adhering to the surface” includes not only the state where the sealant powder is chemically and physically bonded to the corrosion-resistant coating, but also the state where the sealant powder is geometrically caught by the corrosion-resistant coating and does not fall off. .

Since the high-temperature member employing the corrosion-resistant coating having the above-described configuration can seal the pores of the corrosion-resistant coating using a high-temperature atmosphere at the time of use, it is possible to omit a prior firing step.

The corrosion-resistant film of the present invention is a corrosion-resistant film containing 50% by mass or more of one or more selected from ZrO ₂ , Al ₂ O ₃ and SiO _2, and part or all of the pores existing on the surface are sealed as described above. It is filled with a pore agent.

The high-temperature member employing the corrosion-resistant coating having the above-mentioned configuration is because the sealing agent is fixed in the pores of the corrosion-resistant coating, so that the sealing agent layer may fall off during installation during installation or use, The situation where it breaks can be avoided effectively.

The high temperature member of the present invention is characterized in that the above-mentioned corrosion-resistant film is formed on the surface of the base material.

The method for producing a high-temperature member of the present invention includes a step of forming a corrosion-resistant film containing 50% by mass or more of at least one selected from ZrO ₂ , Al ₂ O ₃ and SiO ₂ on a substrate, and the above-described method on the corrosion-resistant film. A sealing agent coating solution is applied. In addition, it is preferable to dry a sealing agent coating liquid after application | coating.

In the present invention, it is preferable to have a step of baking after applying the sealing agent coating solution (or after drying).

It is a photograph which shows the result of SEM observation and EDS analysis of the corrosion-resistant film of sample A. It is a photograph which shows the result of the SEM observation and EDS analysis of the interface of the base layer of sample A, and a corrosion-resistant film. It is a photograph which shows the result of SEM observation and the EDS analysis of the interface of the base layer of sample B, and a corrosion-resistant film. It is a photograph which shows the result of the SEM observation and EDS analysis of the interface of the base layer of sample C, and a corrosion-resistant film. It is a photograph which shows the result of SEM observation and EDS analysis of the corrosion-resistant film of sample D. It is a photograph which shows the result of the SEM observation and EDS observation of the interface of the base layer of sample D, and a corrosion-resistant film.

Hereinafter, embodiments of the present invention will be described.
(Sealing agent)
The sealing agent of this invention seals the pore which exists in a corrosion-resistant film. The corrosion resistant coating to which the sealing agent of the present invention can be applied is not particularly limited, and can be used as a sealing agent for a corrosion resistant coating containing 50% by mass or more of at least one selected from ZrO ₂ , Al ₂ O ₃ and SiO ₂ . The corrosion resistant coating will be described later.

In the glass constituting the sealing agent, the proportion of the alkali metal oxide in the glass composition is 20% by mass or less. Alkali metal oxide is a component for lowering the viscosity of glass to achieve a low softening point, but it causes high temperature corrosion. Therefore, the total amount of alkali metal oxides (Li ₂ O + Na ₂ O + K ₂ O) contained in the glass composition is 0 to 20%, preferably 0 to 18% and 0.1 to 15%. The Li ₂ O content is preferably 0 to 20%, 0 to 15%, 0 to 10%, particularly preferably 0.1 to 5%, and the Na ₂ O content is preferably 0 to 20%, 0 to 15% and 0.1 to 12% are preferable. The content of K ₂ O is preferably 0 to 20%, 0 to 15%, particularly preferably 0.1 to 13%.

The glass constituting the sealing agent is preferably a glass containing ZnO and / or B ₂ O ₃ as an essential component. As a more specific glass composition, ZnO + B ₂ O ₃ 10 to 95% by mass, ZnO 0 to 80%, B ₂ O ₃ 0 to 50%, MgO + CaO + SrO + BaO 0 to 80%, Li ₂ O + Na ₂ O + K ₂ O 0 to 20%, SiO ₂ 0-50%, Al ₂ O ₃ 0-30%, especially ZnO + B ₂ O ₃ 20-95% by mass percentage, ZnO 10-70%, B ₂ O ₃ 10-45%, MgO + CaO + SrO + BaO 1 to 65%, Li ₂ O + Na ₂ O + K ₂ O 0 to 18%, SiO ₂ 0 to 40%, Al ₂ O ₃ 0 to 20% can be used. The reason for limiting the glass composition as described above will be described below. In the following description, “%” means mass%. The glass constituting the sealant may be amorphous glass or crystalline glass.

B ₂ O ₃ is a glass network-forming oxide. B ₂ When the content of O ₃ is too large will water resistance is low, the handling of a normal humidity becomes difficult. B ₂ When the content of O ₃ is too small glass tends to be devitrified and becomes unstable. The content of B ₂ O ₃ is preferably 0 to 50%, 5 to 45%, 10 to 45%, 10 to 40%, more than 10 to 35%, particularly preferably 20 to 35%.

ZnO is a component contributing to glass formation as an intermediate oxide. When there is too much content of ZnO, it will become easy to devitrify. If the content of ZnO is too small, the melting temperature becomes high and it becomes difficult to melt, or the glass becomes unstable. The content of ZnO is preferably 0 to 80%, 1 to 75%, 5 to 72%, 10 to 70%, particularly preferably 15 to 68%.

MgO + CaO + SrO + BaO is preferably 0 to 80%, 1 to 65%, particularly 3 to 25%. When there is too much MgO + CaO + SrO + BaO, it will become easy to devitrify.

MgO is a component that lowers the melting temperature of the glass and adjusts the thermal expansion coefficient. When there is too much content of MgO, it will become easy to devitrify. If the content of MgO is too small, the melting temperature becomes high and it becomes difficult to melt. The MgO content is preferably 0 to 40%, 1 to 25%, particularly 2 to 10%.

CaO is a component that lowers the melting temperature of the glass and adjusts the thermal expansion coefficient. When there is too much content of CaO, it will become easy to devitrify. If the content of CaO is too small, the melting temperature becomes high and it becomes difficult to melt. The CaO content is preferably 0 to 40%, 1 to 30%, particularly 2 to 20%.

SrO is a component that lowers the melting temperature of the glass and adjusts the thermal expansion coefficient. When there is too much content of SrO, it will become easy to devitrify. If the content of SrO is too small, the melting temperature becomes high and it becomes difficult to melt. The SrO content is preferably 0 to 40%, 1 to 30%, particularly 2 to 20%.

BaO is a component that lowers the melting temperature of the glass and adjusts the thermal expansion coefficient. When there is too much content of BaO, it will become easy to devitrify. If the content of BaO is too small, the melting temperature becomes high and it becomes difficult to melt. The BaO content is preferably 0 to 50%, 1 to 40%, 2 to 30%, particularly preferably 3 to 25%.

MgO + CaO + SrO + BaO + ZnO is preferably 10 to 80%, 20 to 75%, particularly preferably 25 to 70%. “MgO + CaO + SrO + BaO + ZnO” means the total content of MgO, CaO, SrO, BaO and ZnO.

Li ₂ O + Na ₂ O + K ₂ O is as described above, and a description thereof is omitted here.

SiO ₂ is a network-forming oxide of glass, and is a component that contributes to glass formation and simultaneously increases water resistance. When the content of SiO ₂ is too large it tends to be devitrified. If the content of SiO ₂ is too small, the water resistance becomes low and the glass becomes unstable. The content of SiO ₂ is preferably 0 to 50%, 0 to 45%, 0 to 40%, 3 to 40%, particularly 5 to 30%.

Al ₂ O ₃ is a component that increases water resistance and increases the viscosity of the glass. When the content of Al ₂ O ₃ is too large it tends to be devitrified. When the content of Al ₂ O ₃ is too small to become water resistance low handling at normal humidity it becomes difficult. The content of Al ₂ O ₃ is preferably 0 to 30%, 0 to 20%, 1 to 20%, particularly 3 to 15%.

In addition to the above components, P ₂ O ₅ , TiO ₂ , MnO ₂ , Fe ₂ O ₃ , CoO, NiO, CuO, Y ₂ O ₃ , ZrO ₂ , SnO ₂ , and La ₂ are within a range that does not impair the desired characteristics. O ₃ , CeO ₂ , Bi ₂ O _{3 and the} like may be included up to 10% each.

The glass constituting the sealant preferably has a thermal expansion coefficient at 30 to 380 ° C. of 30 to 120 × 10 ⁻⁷ / K, particularly 50 to 90 × 10 ⁻⁷ / K. If the thermal expansion coefficient is too high or too low, cracks caused by the difference in thermal expansion from the base material become large, and there is a possibility that the surface of the corrosion-resistant coating will fall off during the cooling process of the power generation equipment.

The glass constituting the sealant preferably has a softening point of 900 ° C. or lower, 850 ° C. or lower, particularly 800 ° C. or lower. If the softening point is too high, the glass becomes difficult to be in a molten state in the operating temperature range. The lower the softening point, the more advantageous. However, if the softening point is too low, the viscosity of the glass in the operating temperature range becomes too low and the glass may be washed away from the surface of the corrosion-resistant coating. In such a case, the softening point is preferably 400 ° C. or higher, particularly 500 ° C. or higher.

Moreover, in the sealing agent of this invention, in order to obtain the sealing agent which can seal the pore of a corrosion-resistant film over a long period of time, it is preferable to employ | adopt especially the following glass I or glass II. Hereinafter, each glass will be described.
[Glass I]
The glass I constituting the sealant is an amorphous glass and has a softening point of 900 ° C. or less.

The softening point of glass I is preferably 850 ° C. or lower, particularly preferably 800 ° C. or lower. If the softening point is too high, the glass becomes difficult to be in a molten state in the operating temperature range. The lower the softening point, the more advantageous. However, if the softening point is too low, the viscosity of the glass in the operating temperature range becomes too low and the glass may be washed away from the surface of the corrosion-resistant coating. In such a case, the softening point is preferably 400 ° C. or higher, particularly 500 ° C. or higher.

In the glass I, the proportion of the alkali metal oxide in the glass composition is 20% by mass or less. Alkali metal oxide is a component for lowering the viscosity of glass to achieve a low softening point, but it causes high temperature corrosion. Therefore, the total amount of alkali metal oxides contained in the glass composition (Li ₂ O + Na ₂ O + K ₂ O) is 0-20%, 0.1-18%, 1-15%, especially 5-12%. Is preferred. The Li ₂ O content is preferably 0 to 20%, 0 to 15%, 0 to 10%, particularly preferably 0.1 to 5%, and the Na ₂ O content is preferably 0 to 20%, 0. It is preferably 1 to 15%, 1 to 13%, particularly preferably 1.5 to 12%. The content of K ₂ O is preferably 0 to 20%, 1 to 15%, particularly preferably 5 to 13%.

The glass I is preferably made of a B ₂ O ₃ —ZnO-based amorphous glass. This type of glass has a low softening point and has a property of being easily melted in the operating temperature range of the high temperature member. Also, since it is amorphous, even if it is cooled and solidified after becoming a molten state, it returns to the molten state again by heating, so even if the operation and stop of the power generation equipment are repeated, When the equipment is in operation, the molten state can always be maintained.

For example, the glass I has a glass composition of B ₂ O ₃ 10-50%, ZnO 1-70%, MgO + CaO + SrO + BaO 0-80%, Li ₂ O + Na ₂ O + K ₂ O 0-20%, SiO ₂ 0-50 as a glass composition. %, Al ₂ O ₃ containing from 0 to 30% can be used. The reason for limiting the glass composition as described above will be described below. In the following description, “%” means mass%.

B ₂ O ₃ is a glass network-forming oxide. B handling in the ₂ O ₃ of the content is too great water resistance is lowered normal humidity is difficult. B ₂ When the content of O ₃ is too small glass tends to be devitrified and becomes unstable. The content of B ₂ O ₃ is preferably 10 to 50%, more than 10% to 50%, 15 to 40%, particularly preferably 20 to 35%.

ZnO is a component contributing to glass formation as an intermediate oxide. When there is too much content of ZnO, it will become easy to devitrify and it will become difficult to maintain an amorphous state in a use temperature range. If the content of ZnO is too small, the melting temperature becomes high and it becomes difficult to melt, or the glass becomes unstable. The content of ZnO is preferably 0 to 70%, 1 to 70%, 5 to 60%, 10 to 50%, particularly preferably 15 to 45%.

MgO + CaO + SrO + BaO is preferably 0 to 80%, particularly preferably 5 to 25%. When there is too much MgO + CaO + SrO + BaO, it will become easy to devitrify.

MgO is a component that lowers the melting temperature of the glass and adjusts the thermal expansion coefficient. When there is too much content of MgO, it will become easy to devitrify. If the content of MgO is too small, the melting temperature becomes high and it becomes difficult to melt. The MgO content is preferably 0 to 40%, 1 to 25%, particularly 2 to 10%.

CaO is a component that lowers the melting temperature of the glass and adjusts the thermal expansion coefficient. When there is too much content of CaO, it will become easy to devitrify. If the content of CaO is too small, the melting temperature becomes high and it becomes difficult to melt. The CaO content is preferably 0 to 40%, 1 to 30%, particularly 2 to 20%.

SrO is a component that lowers the melting temperature of the glass and adjusts the thermal expansion coefficient. When there is too much content of SrO, it will become easy to devitrify. If the content of SrO is too small, the melting temperature becomes high and it becomes difficult to melt. The SrO content is preferably 0 to 40%, 1 to 30%, particularly 2 to 20%.

BaO is a component that lowers the melting temperature of the glass and adjusts the thermal expansion coefficient. When there is too much content of BaO, it will become easy to devitrify. If the content of BaO is too small, the melting temperature becomes high and it becomes difficult to melt. The BaO content is preferably 0 to 50%, 1 to 40%, 2 to 30%, and particularly preferably 5 to 25%.

MgO + CaO + SrO + BaO + ZnO is preferably 10 to 80%, 20 to 70%, particularly preferably 25 to 50%. “MgO + CaO + SrO + BaO + ZnO” means the total content of MgO, CaO, SrO, BaO and ZnO.

Li ₂ O + Na ₂ O + K ₂ O is as described above, and a description thereof is omitted here.

SiO ₂ is a network-forming oxide of glass, and is a component that contributes to glass formation and simultaneously increases water resistance. When the content of SiO ₂ is too large it tends to be devitrified. If the content of SiO ₂ is too small, the water resistance becomes low and the glass becomes unstable. The content of SiO ₂ is preferably 0 to 50%, 3 to 45%, particularly 5 to 30%.

Al ₂ O ₃ is a component that increases water resistance and increases the viscosity of the glass. When the content of Al ₂ O ₃ is too large it tends to be devitrified. When the content of Al ₂ O ₃ is too small to become water resistance low handling at normal humidity it becomes difficult. The content of Al ₂ O ₃ is preferably 0 to 30%, 2 to 20%, particularly 4 to 15%.

In addition to the above components, P ₂ O ₅ , TiO ₂ , MnO ₂ , Fe ₂ O ₃ , CoO, NiO, CuO, Y ₂ O ₃ , ZrO ₂ , SnO ₂ , and La ₂ are within a range that does not impair the desired characteristics. O ₃ , CeO ₂ , Bi ₂ O _{3 and the} like may be included up to 10% each.

Glass I preferably has a thermal expansion coefficient at 30 to 380 ° C. of 30 to 120 × 10 ⁻⁷ / K, particularly 50 to 90 × 10 ⁻⁷ / K. If the thermal expansion coefficient is too high or too low, cracks caused by the difference in thermal expansion from the base material become large, and there is a possibility that the surface of the corrosion-resistant coating will fall off during the cooling process of the power generation equipment.
[Glass II]
Glass II constituting the sealant is crystalline glass, and the proportion of the alkali metal oxide in the glass composition is 20% by mass or less. Alkali metal oxide is a component for lowering the viscosity of glass to achieve a low softening point, but it causes high temperature corrosion. Therefore, the total amount of the alkali metal oxide (Li ₂ O + Na ₂ O + K ₂ O) contained in the glass composition is 0-20%, 0-15%, 0.01-10%, especially 0.1-7%. Preferably there is. The Li ₂ O content is preferably 0 to 20%, 0 to 15%, 0 to 10%, particularly preferably 0.1 to 5%, and the Na ₂ O content is preferably 0 to 20%, 0 to It is preferably 15%, 0.01 to 10%, particularly preferably 0.1 to 7%. The content of K ₂ O is preferably 0 to 20%, 0.01 to 10%, particularly preferably 0.1 to 7%.

Glass II has a softening point of 900 ° C. or lower, 850 ° C. or lower, and particularly preferably 800 ° C. or lower. In the operating temperature range, the glass is once melted and crystallized. However, if the softening point is too high, the glass becomes difficult to be melted. The lower the softening point, the more advantageous. However, if the softening point is too low, the viscosity of the remaining glass (glass matrix) remaining after crystallization in the operating temperature range will be too low, and it will be washed away from the surface of the corrosion-resistant coating. There is. In such a case, the softening point is preferably 400 ° C. or higher, particularly 500 ° C. or higher.

The glass II is preferably made of ZnO—B ₂ O ₃ based crystalline glass. This type of glass has the property that crystals such as 2ZnO.SiO ₂ and ZnO.B ₂ O ₃ precipitate densely when heated, and it is difficult to react with combustion gas.

For example, glass II has a glass composition of ZnO 10 to 80% by mass, B ₂ O ₃ 0 to 50%, MgO + CaO + SrO + BaO 0 to 50%, Li ₂ O + Na ₂ O + K ₂ O 0 to 20%, SiO ₂ 0 to 50%. %, Al ₂ O ₃ containing from 0 to 30% can be used. The reason for limiting the glass composition as described above will be described below. In the following description, “%” means mass%.

ZnO is a component contributing to glass formation as an intermediate oxide. When there is too much content of ZnO, it will become easy to devitrify. If the content of ZnO is too small, the melting temperature becomes high and it becomes difficult to melt, or the glass becomes unstable. Moreover, it becomes difficult to precipitate crystals at the operating temperature. The content of ZnO is preferably 10 to 80%, 20 to 75%, 30 to 72%, 40 to 70%, particularly 45 to 68%.

B ₂ O ₃ is a glass network-forming oxide. B handling in the ₂ O ₃ of the content is too great water resistance is lowered normal humidity is difficult. B ₂ When the content of O ₃ is too small glass tends to be devitrified and becomes unstable. The content of B ₂ O ₃ is preferably 0 to 50%, 5 to 40%, more than 10 to 35%, particularly preferably 15 to 30%.

MgO + CaO + SrO + BaO is preferably 0 to 50%, particularly preferably 3 to 25%. When there is too much MgO + CaO + SrO + BaO, it will become easy to devitrify.

MgO is a component that lowers the melting temperature of the glass and adjusts the thermal expansion coefficient. When there is too much content of MgO, it will become easy to devitrify. If the content of MgO is too small, the melting temperature becomes high and it becomes difficult to melt. The MgO content is preferably 0 to 40%, 1 to 25%, particularly 2 to 10%.

CaO is a component that lowers the melting temperature of the glass and adjusts the thermal expansion coefficient. When there is too much content of CaO, it will become easy to devitrify. If the content of CaO is too small, the melting temperature becomes high and it becomes difficult to melt. The CaO content is preferably 0 to 40%, 1 to 30%, particularly 2 to 20%.

SrO is a component that lowers the melting temperature of the glass and adjusts the thermal expansion coefficient. When there is too much content of SrO, it will become easy to devitrify. If the content of SrO is too small, the melting temperature becomes high and it becomes difficult to melt. The SrO content is preferably 0 to 40%, 1 to 30%, particularly 2 to 20%.

BaO is a component that lowers the melting temperature of the glass and adjusts the thermal expansion coefficient. When there is too much content of BaO, it will become easy to devitrify. If the content of BaO is too small, the melting temperature becomes high and it becomes difficult to melt. The BaO content is preferably 0 to 50%, 1 to 40%, 2 to 30%, particularly preferably 3 to 25%.

MgO + CaO + SrO + BaO + ZnO is preferably 10 to 80%, 30 to 75%, particularly preferably 45 to 70%. “MgO + CaO + SrO + BaO + ZnO” means the total content of MgO, CaO, SrO, BaO and ZnO.

Li ₂ O + Na ₂ O + K ₂ O is as described above, and a description thereof is omitted here.

SiO ₂ is a network-forming oxide of glass, and is a component that contributes to glass formation and simultaneously increases water resistance. When the content of SiO ₂ is too large it tends to be devitrified. If the content of SiO ₂ is too small, the water resistance becomes low and the glass becomes unstable. The content of SiO ₂ is preferably 0 to 50%, 3 to 45%, particularly 5 to 30%.

Al ₂ O ₃ is a component that increases water resistance and increases the viscosity of the glass. When the content of Al ₂ O ₃ is too large it tends to be devitrified. When the content of Al ₂ O ₃ is too small to become water resistance low handling at normal humidity it becomes difficult. The content of Al ₂ O ₃ is preferably 0 to 30%, 1 to 20%, particularly 3 to 15%.

In addition to the above components, P ₂ O ₅ , TiO ₂ , MnO ₂ , Fe ₂ O ₃ , CoO, NiO, CuO, Y ₂ O ₃ , ZrO ₂ , SnO ₂ , and La ₂ are within a range that does not impair the desired characteristics. O ₃ , CeO ₂ , Bi ₂ O _{3 and the} like may be included up to 10% each.

Glass II preferably has a coefficient of thermal expansion at 30 to 380 ° C. after crystallization of 30 to 120 × 10 ⁻⁷ / K, particularly 50 to 90 × 10 ⁻⁷ / K. If the thermal expansion coefficient is too high or too low, cracks caused by the difference in thermal expansion from the base material become large, and there is a possibility that the surface of the corrosion-resistant coating will fall off during the cooling process of the power generation equipment.
[Grain size of glass powder]
The glass constituting the sealing agent is preferably a glass powder having an average particle diameter of 10 nm to 500 μm, particularly 1 to 100 μm. Here, the “average particle size” is defined by D50 calculated on the basis of the number of particles when the particle size of an arbitrary powder is measured by the laser diffraction scattering method.
(Sealing agent coating solution)
The sealant coating solution of the present invention refers to a paste or slurry obtained by mixing a sealant with various resins, paints, organic solvents, water and other inorganic solvents. By making it into a paste or slurry, it becomes easy to apply uniformly on the corrosion-resistant coating. Also, the resin or paint has a function of fixing the sealing agent on the coating until the sealing agent softens and does not fall off from the corrosion-resistant coating. As such a resin or paint, for example, an unsaturated polyester resin, an epoxy resin, a silicone resin, or polytitanocarboxylsilane can be used. Among these, it is most preferable to employ a silicone resin that has high heat resistance and a small reducing action at a temperature at which the sealing agent becomes a molten state (melt).
(Corrosion resistant coating)
The corrosion-resistant film of the present invention is a corrosion-resistant film containing 50% by mass or more of one or more selected from ZrO ₂ , Al ₂ O ₃ and SiO ₂ . This type of corrosion-resistant coating can have corrosion resistance against corrosive and oxidizing combustion gas atmospheres of oxygen, sulfur oxides, hydrogen sulfide, etc. at 500 to 1000 ° C., for example.

Examples of the corrosion resistant coating include a corrosion resistant coating having stabilized ZrO ₂ as a main constituent (hereinafter referred to as a stabilized ZrO ₂ -based corrosion resistant coating). Stabilized ZrO ₂ is mainly composed of ZrO ₂ , and one or more kinds of stable selected from Y ₂ O ₃ , MgO, CaO, SiO ₂ , CeO ₂ , Yb ₂ O ₃ , Dy ₂ O ₃ , HfO _{2 and the} like. An agent is added. Specifically, the ZrO ₂ content is 85% by mass or more, preferably 85 to 95% by mass, and the stabilizer content is 15% by mass or less, preferably 5 to 15% by mass. To do. If the ZrO ₂ content is 85% by mass or more, the corrosion resistance of the coating can be ensured, and the phase from the tetragonal or cubic to monoclinic phase of ZrO ₂ generated near 1000 ° C. in the cooling process after plasma spraying. Metastasis can also be suppressed. Incidentally the content of ZrO ₂ is less than 85 wt%, the corrosion resistance of the coating is reduced.

The porosity of the corrosion-resistant film is preferably 5% or less, particularly 4% or less. By densifying the corrosion-resistant film, it becomes possible to further prevent the corrosion of the base material caused by the acidic gas permeating the film. When the porosity of the corrosion-resistant coating is too high, it becomes difficult to completely seal the pores with the sealing agent, and it becomes difficult to suppress permeation of acid gas. Here, “porosity is 5% or less” means that when the cross section of the corrosion-resistant coating is observed with a scanning electron microscope at a magnification of 1000 times, the ratio of the total area of cracks and voids to the surface of the observation screen is 5%. It means the following.

The thickness of the corrosion-resistant film is preferably 10 to 1000 μm, 10 to 500 μm, 50 to 400 μm, particularly preferably 70 to 300 μm. If the thickness of the corrosion-resistant film is too small, it is difficult to suppress permeation of acidic gas. On the other hand, when the film thickness of the corrosion-resistant film is too large, the thermal stress generated by the thermal cycle increases, and the corrosion-resistant film easily peels off. The porosity of the corrosion-resistant coating can be adjusted by changing the particle size of the sprayed powder (stabilized ZrO ₂ powder or inorganic glass powder).
(High temperature member)
The high temperature member of the present invention preferably has the above-mentioned corrosion-resistant film formed thereon. In addition, as a material of a high temperature member main body (base material), the metal material which has at least one of Fe, Ni, Co, and Cr as a main component is preferable. The corrosion-resistant coating is preferably formed directly on the substrate, but for the purpose of improving adhesion and the like, one or more underlayers may be provided between the substrate and the corrosion-resistant coating.

For example, when the above-described stabilized ZrO ₂ -based corrosion-resistant film is formed on a substrate made of SUS, a layer made of, for example, an M—Cr—Al—Y alloy (M = Ni, Co, Fe) is used as the underlayer. It is preferable to provide it. The M-Cr-Al-Y alloy is an alloy containing Ni or Co, which has excellent properties of high temperature oxidation resistance and high temperature corrosion resistance, with Cr, Al and Y added. This type of alloy is characterized in that it easily adheres to both SUS and the stabilized ZrO ₂ -based corrosion resistant coating.

The porosity of the underlayer is preferably 1% or less. From the viewpoint of suppressing permeation of acid gas, the lower the porosity of the underlayer, the more advantageous.

The film thickness of the underlayer is preferably 10 to 500 μm, particularly 50 to 400 μm, more preferably 70 to 350 μm. From the viewpoint of suppressing permeation of acid gas, the thicker the base layer, the more advantageous. In addition, the underlayer generally has an effect of relieving thermal stress due to the difference in thermal expansion characteristics generated at the interface between the base material and the corrosion-resistant film, but it is difficult to obtain a thermal stress mitigating effect if the underlayer is too thin. Become. On the other hand, if the film thickness of the underlayer is too large, thermal stress generated by a heat cycle or the like inside the power generation facility increases, and the underlayer is easily peeled off. The porosity of the underlayer can be adjusted by changing the particle size of the M-Cr-Al-Y alloy powder to be sprayed.

The high-temperature member is preferably a thermal power generation turbine or heat transfer tube that generates power by collecting kinetic energy or thermal energy via a fluid such as steam or air. However, it is not limited to these. For example, it can be suitably applied to various engines.
(Method for manufacturing high temperature member)
Next, a method for producing a high-temperature member using the sealing agent of the present invention is a stabilized ZrO ₂ -based corrosion-resistant coating film on a base material made of SUS and through an underlayer made of an M—Cr—Al—Y-based alloy. An example of forming the case will be described. In the following description, if a metal tube is used as the substrate, a heat transfer tube with a corrosion-resistant coating can be produced. The production method of the present invention is not limited to the following description. Of course, it goes without saying that the formation of the underlayer is not an essential requirement.

First, an underlayer made of an M—Cr—Al—Y alloy is formed on a base material made of SUS.

The formation of the underlayer is not particularly limited, but is preferably formed by gas spraying such as high-speed flame spraying (HVOF). By using high-speed flame spraying, it becomes easy to obtain a base layer having good adhesion to SUS as a base material and low porosity. Further, it is preferable to use a powder made of an M—Cr—Al—Y alloy as the thermal spraying powder used at this time. The M—Cr—Al—Y alloy is as described above, and the description thereof is omitted here. The average particle size of the sprayed powder is preferably 10 to 75 μm, 10 to 53 μm, and particularly preferably 10 to 45 μm. When the particle size of the thermal spray powder is large, the porosity of the base layer formed by gas spraying is increased. In addition, if the particle size of the sprayed powder is small, clogging of the jet port called the port, which supplies the sprayed powder to gas or plasma, is likely to occur, and it takes time to form a sprayed coating with an arbitrary film thickness. Cost is likely to increase.

Next, a stabilized ZrO ₂ -based corrosion resistant coating is formed on the underlayer made of the M—Cr—Al—Y alloy.

The stabilized ZrO ₂ -based corrosion resistant coating can be formed by a plasma spraying method. As the plasma spraying method, various methods such as an atmospheric pressure plasma spraying method and a vacuum plasma spraying method can be used. It is preferable to use stabilized ZrO ₂ powder as the thermal spraying powder used at this time. The corrosion resistant coating can be formed by a spraying technique other than plasma spraying (for example, gas spraying), a cold spray, an aerosol deposition method, or the like.

The average particle size of the stabilized ZrO ₂ powder is preferably 10 to 75 μm, 10 to 53 μm, particularly 10 to 45 μm. When the average particle size of the stabilized ZrO ₂ powder is large, the porosity of the corrosion-resistant coating formed by plasma spraying is increased. In addition, if the average particle size of the stabilized ZrO ₂ powder is small, clogging of the spray port (port) for supplying the sprayed powder to the plasma is likely to occur, and it takes time to form a sprayed coating having an arbitrary film thickness. Thermal spraying cost tends to be high.

Subsequently, a sealing agent layer is formed on the stabilized ZrO ₂ -based corrosion resistant coating.

For forming the sealant layer, for example, a paste or slurry containing the above-mentioned sealant is applied onto the corrosion-resistant film by a method such as brushing or spraying, and further dried as necessary. In this way, a sealant layer can be formed. It should be noted that other methods may be employed as long as the sealing agent powder does not fall off the corrosion-resistant coating, such as sputtering and thermal spraying.

The sealant layer of the high temperature member thus produced is in a state where the sealant powder is adhered to the surface of the corrosion-resistant coating, and is not yet in a state of completely closing the pores, Can be installed. That is, when the use is started, it is exposed to a high temperature atmosphere, and the heat causes the sealing agent to soften and flow to fill pores existing on the surface of the corrosion-resistant coating.

In producing the high-temperature member of the present invention, firing may be performed after the sealing agent layer is dried (and before actual use). As firing conditions, for example, 300 to 1000 ° C. and 10 minutes to 2 hours are preferable. By firing in advance before actual use, it is possible to prevent the sealant layer from falling off or being damaged during transfer or installation at the place of use.

Hereinafter, based on an Example, this invention is demonstrated in detail.
Example 1
[Preparation of sealant]
Table 1 shows Examples (Sample Nos. 1 to 6) of the sealing agent of the present invention using Glass I.

Each sample was prepared as follows. First, a glass batch prepared to have the composition in the table was melted at 1300 ° C. for 1 hour. Next, after forming this into a film, it was pulverized and classified to obtain a sealing agent made of glass powder having an average particle size of 50 μm. About the obtained sample, the softening point and the thermal expansion coefficient were measured. Moreover, the presence or absence of crystal precipitation was evaluated.

The softening point was measured using a differential thermal analyzer in accordance with the method described by Masayuki Yamane, “For the first glass maker”. The thermal expansion coefficient was calculated as an average linear thermal expansion coefficient of 30 to 380 ° C. from a thermal expansion curve obtained by pressing a sample into a rod shape and firing at 800 ° C. for 20 minutes and then using a dilatometer. Each sample was heat-treated at a softening point of + 40 ° C. for 30 minutes, and then observed for the presence of crystals by an optical microscope. As a result, no crystal was precipitated in any of the samples, and it was confirmed that the sample was amorphous glass.
[Production of high-temperature components]
Next, sample no. A high temperature member (sample A) was prepared using the glass No. 1.

Sample A was prepared as follows. First, SUS310S base material is degreased, washed, and then blasted, and alloy powder with an average particle size of 10 to 45 μm made of a Co—Ni—Cr—Al—Y alloy is sprayed at high speed to provide high temperature oxidation resistance and high temperature resistance. A base layer (Co—Ni—Cr—Al—Y alloy layer) excellent in corrosivity was formed. The thickness of the underlayer was uniform and was 200 to 400 μm. The film thickness of the underlayer was measured with a micrometer. The film thickness can be adjusted by first moving the thermal spraying device parallel to the substrate and spraying it, and measuring with a micrometer how much film thickness can be obtained with a single spray. This was done by adjusting the number of times.

Next, 8% Y ₂ O ₃ —ZrO ₂ powder having an average particle size of 10 to 45 μm was sprayed at atmospheric pressure on the underlayer to form a corrosion-resistant coating. The film thickness of the corrosion-resistant film was uniform and was 50 to 200 μm. The adjustment and measurement of the thickness of the corrosion-resistant coating were performed in the same manner as when the Co—Ni—Cr—Al—Y alloy was sprayed.

Subsequently, a sealant layer was formed on the corrosion-resistant film by the following method. First, silicone resin and sample no. 1 sealant was mixed to prepare a sealant paste. Next, a sealant paste was applied onto the corrosion-resistant film by brushing and then baked at 800 ° C. for 4 days. A sample A was thus obtained.

Also, a high temperature member sample B was prepared for comparison.

Sample B was prepared as follows. First, in the same manner as Sample A, an underlayer and a corrosion-resistant film were formed on a substrate. Next, a glass raw material (mixture of boric acid and sodium carbonate) prepared to have a composition of 32% by mass of B ₂ O ₃ and 68% of Na ₂ O is applied on the corrosion-resistant coating and then baked at 800 ° C. for 4 hours. A sample B was obtained.

Further, as a reference for judging the reactivity of the sealing agent, a sample C on which only the base layer and the corrosion-resistant film were formed was prepared. Sample C was prepared in the same manner as Sample A, except that no sealant layer or the like was formed.

The samples A and B thus obtained were evaluated for permeability and reactivity into the coating. The results are shown in FIGS. FIG. 4 shows the results of SEM observation and EDS analysis of Sample C.

As is apparent from FIGS. Sample A using a sealing agent composed of 1 B ₂ O ₃ —ZnO-based amorphous glass was excellent in permeability to pores and hardly reacted with the underlayer. On the other hand, it was confirmed that the sample B reacted strongly with the underlayer as apparent from FIG. These facts show that the sealing agent of the present invention has high sealing properties and is excellent in long-term stability without corroding the coating.

For the permeability, the cut sample was embedded in a resin, the cut surface was polished, and then the cut surface was subjected to SEM (scanning electron microscope) observation and EDS (energy dispersive X-ray analysis) analysis. Note that not all pores in the corrosion-resistant coating penetrate through the outside. Therefore, there is no problem even if independent pores exist.
(Example 2)
[Preparation of sealant]
Table 2 shows examples of the sealing agent of the present invention using glass II (sample Nos. 7 to 12).

Each sample was produced as follows. First, a glass batch prepared to have the composition in the table was melted at 1300 ° C. for 1 hour. Next, after forming this into a film, it was pulverized and classified to obtain a sealing agent made of glass powder having an average particle size of 50 μm. About the obtained sample, the softening point and the thermal expansion coefficient were measured by the above-mentioned method. Moreover, when the presence or absence of the crystal precipitation was evaluated by the above-described method, the crystal precipitation was confirmed in any of the samples.
[Production of high-temperature components]
Next, sample no. A high temperature member (sample D) was produced in the same manner as in Example 1 using the glass No. 7. For comparison, Sample B prepared in Example 1 was used.

For the high-temperature member sample D thus obtained, the permeability and reactivity to the coating were evaluated. The results are shown in FIGS.

As is apparent from FIGS. Sample D using a sealing agent composed of ZnO—B ₂ O ₃ based crystalline glass No. 7 was excellent in permeability to pores and hardly reacted with the underlayer. On the other hand, it was confirmed that the sample B reacted strongly with the underlayer as apparent from FIG. These facts show that the sealing agent of the present invention has high sealing properties and is excellent in long-term stability without corroding the coating.

The corrosion-resistant coating using the sealant of the present invention is a protective film for a thermal power generation turbine or heat transfer tube that recovers kinetic energy or thermal energy from a high-temperature combustion gas via a fluid such as steam or air. It is preferable to use it. Specifically, it is suitable as a protective film for turbines and heat transfer tubes of gas turbine power generation, coal thermal power generation, coal gasification combined power generation, oil thermal power generation, waste power generation, geothermal power generation, and the like. However, the present invention is not limited to these, and is also suitable as a protective film for various engines. The high-temperature member of the present invention is suitable as a turbine or heat transfer tube for various types of engines such as gas turbine power generation, coal-fired power generation, coal gasification combined power generation, oil-fired power generation, waste power generation, and geothermal power generation.

1 sealing agent 2 corrosion-resistant film 3 underlayer 4 Al ₂ O ₃ over layer 5 resin

Claims (14)

1. A sealing agent for sealing pores of a corrosion-resistant film, comprising a glass having a proportion of alkali metal oxide in the composition of 20% by mass or less.
2. Sealing agent according to claim 1, characterized in that the ZnO and / or B ₂ O ₃ glass containing as essential components.
3. A sealing agent for sealing pores of a corrosion-resistant coating, characterized by comprising an amorphous glass having a softening point of 900 ° C. or less and an alkali metal oxide content in the composition of 20% by mass or less. Sealing agent.
4. Amorphous glass has a glass composition of B ₂ O ₃ 10-50% by mass, ZnO 0-70%, MgO + CaO + SrO + BaO 0-80%, Li ₂ O + Na ₂ O + K ₂ O 0-20%, SiO ₂ 0- The sealing agent according to claim 3, which contains 50% and Al ₂ O ₃ 0 to 30%.
5. The sealing agent according to claim 3 or 4, wherein the amorphous glass is B ₂ O ₃ -ZnO-based glass.
6. A sealing agent for sealing pores of a corrosion-resistant film, comprising a crystalline glass in which the proportion of alkali metal oxide in the composition is 20% by mass or less.
7. The crystalline glass has a glass composition of ZnO 10-80% by mass, B ₂ O ₃ 0-50%, MgO + CaO + SrO + BaO 0-50%, Li ₂ O + Na ₂ O + K ₂ O 0-20%, SiO ₂ 0-50. %, Al ₂ O ₃ 0 to 30%, The sealant according to claim 6.
8. The sealing agent according to claim 6 or 7, wherein the crystalline glass is ZnO-B ₂ O ₃ glass.
9. A sealing agent coating liquid comprising the sealing agent according to any one of claims 1 to 8.
10. A corrosion-resistant film containing 50% by mass or more of one or more selected from ZrO ₂ , Al ₂ O ₃ and SiO _{2, wherein the} powder comprising the sealing agent according to any one of claims 1 to 8 adheres to the surface A corrosion-resistant coating characterized by the above.
11. A corrosion-resistant film containing 50% by mass or more of one or more selected from ZrO ₂ , Al ₂ O ₃ and SiO ₂ , wherein a part or all of the pores existing on the surface are according to any one of claims 1 to 8. A corrosion-resistant film characterized by being filled with a sealing agent.
12. A high-temperature member, wherein the corrosion-resistant film according to claim 10 or 11 is formed on a surface of a substrate.
13. The step of forming a corrosion-resistant film containing 50% by mass or more of at least one selected from ZrO ₂ , Al ₂ O ₃ and SiO ₂ on a substrate, and the sealing agent coating liquid according to claim 9 on the corrosion-resistant film. A method for producing a high-temperature member.
14. The method for producing a high-temperature member according to claim 13, further comprising a step of firing after application of the sealant coating solution.

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