JPH08337487A - Formation of ceramic coating film and ceramic member produced using same - Google Patents

Abstract

PURPOSE: To provide a method for forming a ceramic coating film on a ceramic substrate by which the substrate can be joined to the coating film with satisfactory strength. CONSTITUTION: The objective ceramic coating film is formed through a 1st process in which a middle layer 2 is formed on the surface of a substrate 1 made of an oxide ceramic material by a metallic coating film forming means such as thermal spraying, a 2nd process in which a ceramic outer layer 3 is formed on the surface of the middle layer 2 by thermal spraying and a 3rd process in which the substrate 1 with the formed layers 2, 3 is heat-treated so that at least part of the layer 2 is oxidized. By this oxidation reaction, chemical bonding is caused between the layers 2, 3 and the bonding strength of the substrate 1 to the resultant coating film is enhanced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a ceramic coating by coating the surface of an oxide-based ceramic substrate with an oxide-based ceramic layer by thermal spraying, and a ceramic member produced by the method. .

[0002]

2. Description of the Related Art As one of the methods for improving the surface characteristics of various versatile oxide-based ceramic base materials, the oxide-based ceramic base material having a composition different from that of the oxide-based ceramic base material is used. Methods of spraying layers are known.

[0003]

Here, there is known a method of roughening the surface of a base material by subjecting it to a blast treatment in advance in order to enhance the bonding characteristics obtained by thermal spraying. Simply spray-forming another ceramic material on the roughened oxide-based ceramic base material generally does not provide sufficient bonding strength between these materials, causing peeling during actual operation and withstanding use. There was room for improvement. The reason why the bonding strength is insufficient is that the mere thermal spraying involves the mechanical bonding obtained when the sprayed molten particles enter the recesses of the roughened surface of the ceramic substrate and rapidly solidify. It is thought that it depends only on. In view of the above-mentioned drawbacks of the prior art, it is an object of the present invention to provide a layer of another ceramic material and an oxide-based ceramic substrate in a method of forming another layer of ceramic material on an oxide-based ceramic substrate by thermal spraying. (EN) Provided is a method capable of joining and with a sufficient strength, and a ceramic member produced by the method.

[0004]

In order to achieve the above object, the characteristic constitution of the method for forming a ceramic film on an oxide-based ceramic substrate according to the present invention is that it comprises the following steps. That is, (a) a first step of forming an intermediate layer on the surface of a base material made of an oxide-based ceramic material by means of a metal film forming means, (b) forming a ceramic outer layer on the surface of the formed intermediate layer by thermal spraying. Second step, (c) Third step of heat treating the intermediate layer and the ceramic substrate on which the ceramic outer layer is formed so that at least a part of the intermediate layer is oxidized.

Further, a characteristic constitution of the ceramic member according to the present invention is that a base material made of an oxide-based ceramic material,
An intermediate layer formed on the base material, and a ceramic outer layer formed by thermal spraying on the intermediate layer, the intermediate layer, and at least the intermediate by heat treatment after forming the ceramic outer layer The secondary oxide containing each constituent of the intermediate layer and the ceramic outer layer is formed near the interface between the layer and the ceramic outer layer.

[0006]

By performing the third step described in claim 1, at least a part of the intermediate layer formed in the first step is oxidized, and the metal is formed at the interface between the metal intermediate layer and the ceramic outer layer. A secondary oxide having at least a part of the constituents and at least a part of the constituents of the ceramic outer layer as constituents is produced, which causes a strong chemical bond at the interface.

In the first step of the present invention, it is preferable to form a metal film made of a nickel alloy. When the nickel alloy is used as the intermediate metal layer, the metal of the intermediate metal layer is easily oxidized by the heat treatment in the third step, and the oxidized metal is easily diffused. Can be formed.

In the first step of the present invention, as a metal film forming means, a thermal spraying method, various PVD methods (evaporation, sputtering, ion plating, etc.), CVD
Methods, plating, spraying, brush coating, etc. are possible, but among these, it is preferable to adopt the thermal spraying method. By adopting thermal spraying, it becomes possible to obtain a relatively thick intermediate layer at a relatively low cost, and in order to obtain a more reliable coating bond, the secondary oxide can be surely added in the third step. It is convenient in terms of generation and cost.

As the ceramic outer layer forming means in the second step, it is preferable to use the plasma spraying method among the thermal spraying. By using the plasma spraying method, it becomes possible to spray ceramics having a high melting point, and it is easy to obtain a ceramic coating having a large thickness as compared with other spraying methods, and the secondary oxide is surely formed in the third step. By being able to form, it becomes possible to form a ceramic film having high adhesion strength.

Alumina is used as the oxide ceramic substrate, Ni—Cr—Al—Y based material is used as the thermal spray material for forming the metal intermediate layer, and the oxide based ceramic outer layer is formed. An alumina-chromia ceramic material is used as the thermal spray material, and the heat treatment in the third step is preferably performed at 1300 ° C. to 1500 ° C. in an air atmosphere. Oxidation of the metal intermediate layer is further promoted by the selection of such a material and the selection of such processing conditions, and after the metal thus oxidized is diffused into the structure of the oxide ceramic substrate, To generate a secondary oxide with the constituents of the oxide ceramic substrate in the structure of the oxide ceramic substrate,
A chemical bonding mechanism is created between these different layers, and as a result, a ceramic film having high adhesive strength can be formed.

Preferably, the ceramic member of claim 6 is a sleeve for a water-cooled tuyere of a blast furnace. in this case,
The alumina sleeve body serves as the oxide-based ceramic base material, and Ni-Cr- is formed on the inner cylindrical surface of the sleeve body.
A layer formed by spraying an Al-Y-based material serves as the intermediate layer, and an outer layer formed by spraying an alumina-chromia-based ceramic material serves as the ceramic outer layer. By selecting such a material, NiAl ₂ O ₄ in the heat treatment step, and
Since the secondary oxide containing (NiCr) Al ₂ O ₄ is reliably generated, the alumina-chromia ceramic protective coating adheres to the sleeve body more reliably, and therefore, even in the pulverized coal blowing operation, it becomes fine powder. It has become possible to fabricate a water-cooled tuyere sleeve for ironmaking blast furnaces in which ash generated from charcoal is less likely to deposit on the surface.

[0012]

As described above, the oxide-based ceramic substrate is used as a medium by using the metal intermediate layer capable of forming a chemical bond in addition to the mechanical bond by the heat treatment after the thermal spraying. A method for forming a layer of another ceramic material on the above by thermal spraying, which is capable of joining the layer of another ceramic material and the oxide-based ceramic substrate with sufficient strength, and a method for producing the same. It is now possible to provide a ceramic member that has

[0013]

Embodiments of the method for forming a thermal spray coating and the ceramic member according to the present invention will be described in detail with reference to the drawings.
FIG. 1 shows the ceramic substrate used in this example, and
It is what showed the formed film typically. As the ceramic substrate 1, a disc-shaped substrate made of high-purity alumina having a thickness of 5 mm and a diameter of 25 mm was used. The intermediate layer 2 is formed by a plasma spraying method, and the spraying material at that time is Ni-22Cr-10Al having a particle diameter of 45 to 10 μm.
-1Y alloy powder was used. The ceramic outer layer 3 is also formed by the plasma spraying method, and the spraying material at that time is 50%.
Cr ₂ with O ₃ -50% Al ₂ O ₃ powder. The surface of the ceramic substrate 1 was blasted with SiC grit having a grain size of # 24 in order to roughen the surface to be sprayed. The thermal spraying employs plasma spraying using argon as a plasma generating gas, and the thickness of the layer formed by this spraying is 0.1 m in the intermediate layer 2.
m and the outer ceramic layer 3 were 0.6 mm. The heat treatment after each layer thermal spraying was carried out by heating and holding at 1300 ° C. × 4 Hr in an air atmosphere in an electric furnace using a siliconite heating element, and then cooling in the same furnace.

In order to examine the bonding state of the intermediate layer 2 and the ceramic outer layer 3, the cross section of the sample after the above heat treatment was E.
Observed by PMA. As a result, as shown in the composition image photograph of FIG. 2, it was found that both the interface of the intermediate layer 2 with the base material 1 side and the ceramic outer layer 3 side showed a sound bonding state.

Next, in order to investigate the adhesion strength of the formed ceramic outer layer 3, a ceramic spraying test method (JIS
The tensile test was performed according to H8666). The result is shown in FIG. In addition to Ni-22Cr-10Al-1Y, as a thermal spray material for the intermediate layer, 50Ni
When -50Cr and 80Ni-20Cr are used, the heat treatment conditions are 1500 ° C and 130%.
The holding conditions of 4 hours at 0 ° C. and 1400 ° C. were compared and examined. As a result, the adhesion strength of the sample not heat-treated was about 2 MPa, whereas the adhesion strength of the heat-treated sample was about 7 to 20 MPa, which was excellent. Also,
Among these, Ni-22 is used as the thermal spray material for the intermediate layer.
Cr-10Al-1Y (or 50Ni-50Cr)
It can be seen that, when the heat treatment condition is 1300 ° C. (or 1400 ° C.) × 4 Hr, the adhesive strength is particularly excellent.

Further, in order to investigate the thermal shock resistance of the formed film, that is, the intermediate layer 2 and the ceramic outer layer 3, a quenching test was carried out by a method of holding in 200 ° C. × 1 Hr and then pouring in water. As a result, the film of the sample that was not heat-treated peeled off by the first immersion in water, whereas the film of the heat-treated sample did not peel even after 10 rapid cooling cycles.

By the way, when observing the fractured sample after the tensile test for investigating the adhesion strength of the above-mentioned coating, in the case of the sample subjected to the heat treatment, the fracture occurred in the base material 1 inside the intermediate layer 2.
It was found that it occurred at a position closer to the side. The composition of the tissue constituting the surface of this fracture surface was investigated by X-ray diffraction. FIG. 4 shows the results. According to this, α-A
l ₂ O ₃ , NiAl ₂ O ₄ , and (NiCr) Al ₂
The presence of O ₄ was recognized. This means that the metal intermediate layer 2 is transformed into Ni and Cr oxides by the heat treatment in the atmosphere, and these oxides penetrate at least the structure of alumina on the base material 1 side by diffusion. , A
NiAl ₂ O ₄ and (NiCr) by interaction with
A secondary oxide such as Al ₂ O ₄ is formed, suggesting that this formation mechanism is involved in the high adhesion strength of the film.

In addition to the results of analysis of the structure constituting the surface of the fracture surface, FIG. 4 shows the Ni-- before spraying.
22Cr-10Al-1Y powder, Ni-22Cr-10Al-1Y in a state of only being sprayed but not heat treated
The results of X-ray diffraction analysis are also shown for the layers, and only the Ni-22Cr-10Al-1Y layer after thermal spraying was heat-treated at 1300 ° C. and 1500 ° C. for 4 hours each. As a result,
No substantial phase change has occurred only by the thermal spraying process,
Further, it is shown that when Ni-22Cr-10Al-1Y is heat-treated, the growth of NiCr ₂ O ₄ and NiCrO ₃ is generally accelerated as the treatment temperature is increased. This result shows that the NiAl observed on the fracture surface of the film adhesion strength test sample of the ceramic member of the above example.
_It supports the formation mechanism of ₂ O ₄ and (NiCr) Al ₂ O ₄ .

By the way, in producing the ceramic member as shown in the above-mentioned embodiment by using the method of the present invention, as the oxide-based ceramic base material 1, in addition to the high-purity alumina used in the above-mentioned embodiment, alumina-magnesia is used. , Alumina-zirconia, alumina-silica, alumina-chromia, alumina-chromia-zirconia, and other alumina-based materials, zirconia-based materials, chromia-based materials, and the like can be used. Further, as the thermal spraying material for the metal intermediate layer 2, in addition to Ni-22Cr-10Al-1Y used in the above-mentioned example, 80
Ni-20Cr, 50Ni-50Cr, 95Ni-5A
1, 80Ni-20Al or the like can be used. further,
As the thermal spray material for the ceramic outer layer 3, in addition to the alumina-chromia material used in the above-mentioned examples, alumina,
Alumina-titania, alumina-zirconia, alumina-silica, alumina-magnesia, zirconia, zirconia-yttria, zirconia-magnesia, zirconia-calcia, zirconia-silica, titania, alumina-zirconia-silica and the like can be used.

Further, in this embodiment, the plasma spraying method was adopted as the metal film forming means, but other spraying methods such as gas spraying can be adopted, and the purpose of using the ceramic member as a finished product, Various PVD methods (evaporation, sputtering, ion plating, etc.), CVD methods, plating, spraying, brush coating, etc. can also be adopted depending on the suitability for the materials used.

[Other Embodiments] Here, an example in which the method of the present invention shown in the above embodiments is applied to a ceramic sleeve for a water-cooled tuyere of a pig-making blast furnace that performs a pulverized coal blowing operation will be described. Alumina-based materials are known as materials for the ceramic sleeve, because the alumina-based materials are excellent in heat resistance, mechanical strength at high temperatures, abrasion resistance, and corrosion resistance. However, under the above-mentioned pulverized coal blowing operation, the ash mainly composed of SiO ₂ —Al ₂ O ₃ generated from the pulverized coal builds up on the surface of the sleeve, especially the inner cylinder, and the inner cylinder of the sleeve becomes partially narrowed. Problems tend to occur. On the other hand, a method of forming the sleeve by using a Cr ₂ O ₃ -based material, which is known as a material mainly composed of SiO ₂ -Al ₂ O _{3 and} having low wettability with ash, can be considered. However, a sinter molding material having a high chromia content is difficult to realize due to manufacturing problems in shape and size.

Therefore, it is conceivable to provide a sleeve having a surface property with low wettability to ash content by applying a spray coating of a chromia material to the alumina-based sleeve body having good moldability. However, if the chromia-based material is simply formed by thermal spraying on the alumina-based sleeve body having the roughened surface, the bonding strength of the chromia-based material coating to the surface of the alumina-based sleeve body is sufficient. Therefore, there is room for improvement because the ceramic coating is easily peeled off from the main body ceramic. As described above, the reason why the bonding strength is insufficient is that, in the mere thermal spraying, the sprayed molten particles of the chromia-based material enter the concave portion of the roughened surface of the alumina-based sleeve body and are rapidly cooled and solidified. It is considered that it depends only on the mechanical coupling obtained.

Since the tuyere sleeve shown in this other embodiment is manufactured according to the method of the present invention, the above problems are remarkably improved.

FIG. 5 is a cross-sectional view of the tuyere attached to the furnace wall of the blast furnace. The left front side of the furnace wall 4 indicates the inside of the furnace. The tuyere sleeve body 61 as another embodiment is attached to the inner cylindrical surface of the tuyere 6, and the tuyere 6 communicates with the blow pipe 5. The pulverized coal (the main component of the ash of the pulverized coal is SiO ₂ —Al ₂ O ₃ ) is sprayed onto the inner cylindrical surface of the tuyere sleeve body 61 on the extension line of the pulverized coal blowing pipe 7.

FIG. 6 is a schematic view of a cross section of the inner cylindrical surface of the tuyere sleeve 61. The sleeve inner cylindrical surface has a sleeve body 61 made of alumina, a nickel alloy layer 62 as a metal intermediate layer formed on the sleeve body 61, and
It is composed of an alumina-chromia layer 63 as a ceramic coating formed by thermal spraying on the metal intermediate layer 62. The nickel alloy layer 62 as the metal intermediate layer is formed on the inner cylindrical surface of the sleeve body 61 by plasma spraying. At this time, the inner cylindrical surface of the sleeve body 61 is roughened in advance by a blast method or the like. . The alumina-chromia layer 63 as a ceramic coating is also formed on the nickel alloy layer 62 after the thermal spraying by plasma spraying.
Then, in order to increase the adhesive strength of the two-layer coatings 62 and 63, the entire sleeve body 61 on which the two-layer coatings 62 and 63 are formed is placed in an electric furnace or the like, and the temperature is set to 1400 ° C. in an air atmosphere. It was heated for 4 hours and oxidized. In the metal intermediate layer 62 and the ceramic coating 63 on the inner cylindrical surface of the sleeve main body 61 thus oxidized, at least a part of the metal intermediate layer 62 is oxidized and the sleeve main body 61, which is an adjacent member,
Further, since the ceramic coating 63 diffuses into the structure of the ceramic coating 63 and chemically bonds to each other, a good bonded state is exhibited, and high peel resistance is obtained.

As described above, the blast furnace tuyere sleeve of this embodiment is provided with the sprayed metal film as the intermediate layer based on the method of the present invention, and the alumina-chromia ceramic layer sprayed on the intermediate layer. Is provided as the outermost layer, and a chemical bond is generated between the metal intermediate layer and the ceramic structures on both sides by heat treatment of these sprayed films after these spraying steps, so that the alumina-chromia system is used. The ceramic layer is formed in a stable state in which peeling is unlikely to occur.

As a result, even in the operation of blowing pulverized coal, the long-life blast furnace water-cooled tuyere sleeve is resistant to wetting with ash containing SiO ₂ -Al ₂ O ₃ as a main component and has excellent surface characteristics stably. Could be provided.

It should be noted that reference numerals are given in the claims for convenience of comparison with the drawings, but the present invention is not limited to the structures of the accompanying drawings by the entry.

[Brief description of drawings]

FIG. 1 is a schematic view of an oxide-based ceramic member produced by using a method according to the present invention.

FIG. 2 is a photograph of a structure in the vicinity of an intermediate layer of a ceramic member subjected to a 1400 ° C. × 4 Hr oxidation treatment after a thermal spraying process.

FIG. 3 is a diagram showing the relationship between adhesion strength and heat treatment conditions when various alloys are used as materials for the intermediate layer.

FIG. 4 is Ni-22Cr-10Al as an intermediate layer material.
1 is a diagram showing a sprayed metal layer in the case of using -1Y, and a fracture surface X-ray diffraction analysis result after an adhesion strength test.

[Fig. 5] Schematic diagram of tuyere attached to blast furnace of pulverized coal blowing operation

FIG. 6 is a schematic diagram showing a state near the cross section of the inner surface of the tuyere sleeve.

[Explanation of symbols]

 1 Ceramic Substrate 2 Intermediate Layer 3 Ceramic Outer Layer 4 Furnace Wall 5 Blow Pipe 6 Tuyere 7 Pulverized Coal Blowing Pipe 61 Tuyere Sleeve Body 62 Middle Layer on Tuyere Sleeve Body 63 Ceramic Outer Layer on Tuyere Sleeve Body

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[Procedure amendment]

[Submission date] June 13, 1995

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 2

[Correction method] Change

[Correction content]

[Fig. 2]

Claims (9)

[Claims] 1. A method for forming a ceramic film on an oxide-based ceramic substrate, comprising the following steps: (a) a substrate (1, 6) made of an oxide-based ceramic material.
On the surface of 1), an intermediate layer (2, 6
2) a first step of forming, (b) a second step of forming a ceramic outer layer (3, 63) on the surface of the formed intermediate layer (2, 62) by thermal spraying, (c) the intermediate layer (2) , 62) and the ceramic base material (1, 61) having the ceramic outer layer (3, 63) formed thereon is heat-treated so that at least a part of the intermediate layer (2, 62) is oxidized. Third step. 2. The ceramic film forming method according to claim 1, wherein the metal film forming means in the first step is for spraying a nickel alloy. 3. The ceramic coating forming method according to claim 1, wherein the thermal spraying in the third step is thermal spraying by a plasma thermal spraying method. 4. The oxide ceramic substrate (1,61)
Is alumina, the metal sprayed to form the intermediate layer (2, 62) is a Ni-Cr-Al-Y-based alloy, and the oxide-based ceramic outer layer (3, 63) is alumina-chromia. It is a ceramic material and the heat treatment in the third step is performed at 1300 ° C. to 15 ° C. in an air atmosphere.
It is a heat treatment at a temperature of 00 ° C., and the components of the Ni—Cr—Al—Y alloy that are oxidized by the heat treatment are diffused at least in the structure of the oxide ceramic base material (1, 61) and then the oxidation is performed. The method for forming a ceramic film according to claim 2, wherein a secondary oxide is produced by reacting with a constituent component of the oxide ceramic substrate (1, 61) in the structure of the physical ceramic substrate. 5. The secondary oxidation produced in the third step
The thing is NiAl₂O _Four, And (NiCr) Al₂O
_FourThe method for forming a ceramic film according to claim 4, which comprises: 6. A base material (1, 61) made of an oxide ceramic material, and an intermediate layer (2, 2) formed on the base material.
62) and an outer ceramic layer (3, 63) formed on the intermediate layer, the oxide ceramic member comprising the intermediate layer (2, 62) and the outer ceramic layer (3, 63). ) Is formed and then heat-treated to form the intermediate layer (2, 62) and the ceramic outer layer (3, 6).
A ceramic member characterized in that a secondary oxide containing the respective constituent components of the intermediate layer and the ceramic outer layer is formed near the interface of 3). 7. The oxide-based ceramic substrate (1,6)
1) is at least alumina, alumina-magnesia,
Alumina-zirconia, alumina-silica, alumina-
Chromia, alumina-chromia-zirconia, and other materials selected from the group consisting of oxides consisting of alumina, zirconia, and chromia.
62) is at least 80Ni-20Cr, 50Ni-
50Cr, Ni-22Cr-10Al-1Y, 95Ni
-5Al, 80Ni-20Al is formed by thermal spraying a metal material selected from a nickel-based alloy group, and the ceramic material sprayed to form the ceramic outer layer (3, 63) is at least alumina. , An oxide of alumina-titania, alumina-zirconia, alumina-silica, alumina-magnesia, zirconia, zirconia-yttria, zirconia-magnesia, zirconia-calcia, zirconia-silica, titania, alumina-chromia, alumina-zirconia-silica The ceramic member according to claim 6, which is made of a material selected from a group of systems. 8. The oxide-based ceramic substrate (1,6)
1) is alumina, and the intermediate layer (2, 62) is Ni
-Cr-Al-Y type metal is formed by thermal spraying, and the material sprayed to form the ceramic outer layer (3, 63) is an alumina-chromia type ceramic material, and the secondary oxide is Is NiAl ₂ O ₄ and (NiCr) Al ₂ O ₄ . 9. A tuyere sleeve body (61) as the oxide ceramic substrate, and a ceramic protective film (63) formed on an inner cylindrical surface of the sleeve body as the oxide-based ceramic outer layer. The ceramic member according to claim 8, which is a sleeve for a water-cooled tuyere of a blast furnace equipped with the ceramic member.