JP3045463B2 - Steel member having composite sprayed coating and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steel member having a composite sprayed coating having excellent corrosion resistance and molten metal resistance, and a method for producing the same.
It is suitable for use as a member for molten metal such as aluminum alloy plating, various rolls used in the field of hot-dip aluminum plating, bearings, sleeves, bushes, metal fittings for adjusting the amount of plating, and has excellent corrosion resistance. Therefore, it is also effective as a member used in fields such as acid, alkali and molten salt environments.

[0002]

2. Description of the Related Art Plating layers such as hot-dip galvanizing, hot-dip aluminum plating, and hot-dip zinc-aluminum alloy plating exhibit excellent rust and corrosion resistance, and have been used for a long time in automobiles, aircraft, vehicles, construction and home appliances. It is applied to components such as products and is still one of the surface treatment films that still plays a major role. Among them, hot-dip galvanized steel sheets that are mass-produced are often manufactured by a continuous hot-dip galvanizing apparatus.

The continuous hot-dip galvanizing apparatus guides a sink roll immersed in a plating bath, a support roll disposed near a surface in the plating bath, and a plated steel sheet after passing through these rolls. A molten metal member such as a guide roll is used. These components are
It is immersed in a plating bath or installed in a place where molten zinc is easily scattered and adhered, and is used so as to come in contact with hot steel sheet to which molten zinc adheres. (1) Erosion by molten zinc occurs (2) It is hard to be worn even when it comes in contact with the passing material (steel plate), (3) It is easy to peel off the adhered molten zinc and maintenance is easy, and (4) The service life as a plating material is long and low. It is required to be cost-effective and (5) to withstand thermal shock when immersed in a high-temperature molten zinc bath.

In order to meet such a demand, a conventional film for a sink roll is taken as an example. (1) JP-B-56-39709, JP-B-58-11507, and JP-A-59-153875. JIS H8303 (1971) described in JP-A-1-108334, JP-A-64-79356 and JP-A-2-125833.
6) A film having an alloy composition conforming to the established Co-based self-fluxing alloy. (2) JP-A-61-117260, JP-B-3-54
No. 181 and Japanese Patent Publication No. 4-27290, in which an oxide-based ceramic film composed of ZrO ₂ and Al ₂ O ₃ is formed by thermal spraying, (3) Japanese Patent Publication No. 58-37386, As disclosed in JP-A-2-212366, JP-A-2-180755, JP-A-3-94048, JP-A-4-13857 and JP-A-4-346640, carbides and nitrides,
Non-oxide ceramics such as boride, a cermet spray coating formed by coexisting metals such as Cr and Ni, Co, (4) As described in JP-A-4-13857,
A combination of the techniques of (1) and (3). (5) Furthermore, Japanese Patent Publication No.
JP-A-53-128538 in which a film is formed by thermal spraying, and JP-A-4-165058 in which a thermal spray coating of Cr is formed.

[0005] The present inventors have also conducted research and development on similar technologies with respect to the above-mentioned technologies. For example, (6)
No. 63-49846 (Japanese Patent Application Laid-Open No. 1-257661), a WC cermet containing 5-28% of Co and having a porosity of 1.8% for the film.
% Or less, thermal spray coating with a film thickness of less than 0.040 to 0.10 mm,
(7) In Japanese Patent Application No. 63-192753 (JP-A-2-43352), a boride or a material containing 5 to 28% of Co is formed by a low pressure plasma spraying method. Flat one
-54883 (Japanese Patent Application Laid-Open No. 2-236266) discloses that ZrB ₂ , Ti
B ₂ and various carbides in 5-40% of Ta, a material impregnated with Nb used, by vacuum plasma spraying method, which the film surface roughness Ra were formed 0.01 5 .mu.m, porosity of 1.8% or less of the coating , (9) Japanese Utility Model Application No. 1-124010 (Japanese Utility Model Application No. 3-63565)
No.), a film in which Cr ₃ O ₃ is formed by a chemical densification method on a cermet sprayed coating mainly composed of carbide,
(10) In Japanese Patent Application No. 2-201187 (Japanese Patent Application Laid-Open No. 4-88159), a coating obtained by changing a part of a carbide sprayed coating to a boride by boride treatment is disclosed. Japanese Patent Application Laid-Open No. Hei 4-254571) discloses a method in which Al or an Al-Zn alloy is heated and diffused into various carbides, borides or a cermet sprayed coating thereof to improve molten zinc resistance.
2) In Japanese Patent Application No. 3-31448 (JP-A-4-254571), Al or Al-
(13) In Japanese Patent Application No. Hei 3-222425 (Japanese Patent Application Laid-Open No. Hei 4-358055), non-oxide ceramic powder or powder obtained by mixing metal with Al or Al-Al (14) Japanese Patent Application No. 3-213143 (JP-A-5-33113)
No.), a non-oxide ceramic powder or a powder obtained by mixing a metal with this, an Al-Fe alloy or Al-Fe
-Sprayed film formed by using a sprayed material to which a Zn alloy is added, (15) Japanese Patent Application No. 3-266874 (Japanese Patent Application Laid-Open No. 5-78801)
Has proposed various technologies and films, such as a steel roll having an Al—Fe alloy layer having an Al content of 22% or more formed on the surface thereof.

[0006]

On the other hand, a recent study by the inventors has revealed that there is still a problem to be solved regarding the molten metal resistance of the above-mentioned sprayed coating. . That is, (1) A sprayed film formed in the atmosphere always has pores and oxides. For this reason, even if the thermal spray coating material is a substance that does not cause a metallurgical reaction with the molten metal,
The molten metal penetrates into the inside through the pores and reacts with the base metal, thereby peeling and destroying the coating from the root. (2) Metals with a low free energy of oxide formation, such as molten aluminum, are oxides contained in the coating (those that are oxidized in the thermal spraying heat source and contained directly in the coating. In order to reduce), the pores are enlarged, while the metal generated by the reduction causes a metallurgical reaction, causing a volume change and destroying the film. (3) Carbide cermet represented by WC-Co is used as a thermal spray coating for molten metal, but molten metal adheres to metal components contained in the coating or reacts metallurgically. As a result, adhesion of the dross component is promoted, and finally, the quality of the plated steel sheet is deteriorated. (4) Since all the thermal spray members used in the molten metal bath are used in a high temperature environment, it is necessary that the thermal spray members have high heat resistance and high resistance to thermal shock.

A main object of the present invention is to provide a steel member exhibiting an excellent effect when applied to a member for molten metal.
In particular, it is an object of the present invention to provide a steel member having a composite thermal spray coating excellent in corrosion resistance and molten metal resistance. Another object of the present invention is to propose a configuration of the composite sprayed coating having high resistance to peeling and destruction of the coating and also having excellent heat resistance and thermal shock resistance. Still another object of the present invention is to solve the problems described above,
An object of the present invention is to provide a member which exhibits excellent corrosion resistance to an alkali aqueous solution and molten salts such as chlorides, sulfates, and nitrates, and can be advantageously used in such a corrosive environment. Still another object of the present invention is to propose a method for efficiently and reliably forming the composite coating on the surface of a steel base material.

[0008]

In order to solve the above-mentioned problems, the present invention basically employs the following means. First, as a lower layer (undercoat), a thermal spray coating of a cermet composed of a metal (including an alloy), an oxide-based ceramic and a non-oxide-based ceramic, or a ceramic and a metal is formed on the surface of a steel base material. And
As an upper layer (top coat) on the undercoat,
Oxide-based or non-oxide-based ceramics are used as dispersion particles for reinforcement, and these particles are mixed well with a vitreous material as a matrix to form a composite thermal spray coating. The vitreous material used as the matrix of the composite sprayed coating has a melting point in the range of 500 to 750 ° C. and a coefficient of linear expansion in the range of 5 to 14 × 10 ⁻⁶ / ° C.
The mixing ratio of the vitreous material and the oxide or non-oxide ceramic particles is 5 to 95% by weight of the vitreous material.
Within the range, a composite sprayed coating in a mixed state is formed in which uniform dispersion, stepwise variable dispersion, or gradually variable dispersion in which the mixing ratio gradually changes are formed.

Further, in applying a top coat sprayed coating containing ceramic particles as a reinforcing material in a glassy material of a matrix, an undercoat sprayed coating is formed at room temperature or at a temperature maintained at 200 to 500 ° C. Alternatively, after spraying the composite sprayed coating at 400-850 ° C, 0.
Heating for 1 to 5 hours, or if the top coat spray coating is formed on the undercoat spray coating under a temperature condition of less than 200 ° C., after spraying, 400 to 850 ° C., 0.1 to
The heat treatment is performed for 5 hours to eliminate pores of the top coat sprayed coating and form a composite sprayed coating excellent in corrosion resistance and molten metal resistance on the surface of the steel member.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the structure of the present invention will be described below in accordance with the working steps for forming a composite sprayed coating having excellent corrosion resistance and molten metal resistance on the surface of a steel base material. (1) Formation of thermal spray coating as undercoat After degreasing the surface of a steel base material, performing grid-blasting and roughening treatment, apply a metal, oxide or non- An oxide-based ceramic or cermet film is applied to a thickness of 30 to 750 μm to form an undercoat sprayed film composed of one or more layers.
When the thickness of the undercoat sprayed film is thinner than 30 μm, the function as an undercoat is poor.
When it is thicker than 0 μm, it is economically disadvantageous. Desirably, the range of 50 to 250 μm is recommended from the viewpoint of the function as an undercoat and economy.

The following materials can be used as the thermal spray material used for forming the undercoat thermal spray coating. Ni, Fe, Mo, Cr, Co, Ti, T
a, Nb, Al and W, and alloys thereof. As the ceramic material, one or a mixture of two or more of the following: a. _{Al 2 O 3, TiO 2,} MgO, ZrO 2, Ta 2 O 5, Nb 2 O 5, oxides such as SiO _2, b. Carbides such as WC, Cr ₃ C ₂ , NbC, TaC, HfC, MoC, ZrC, TiC, c. _{NiB 2, CrB 2, W 2} B 5, TiB 2, ZrB 2, NbB 2, borides such TaB _2, d. As nitride cermet materials such as TiN, VN, NbN, TaN, HfN, ZrN, BN, Si ₃ N ₄ , and CrN, use a mixed powder of the above-mentioned metal-based materials and ceramic-based materials or a sintered material powder be able to. The thermal spraying material may be a metal material, a ceramic material, or a cermet material alone or as a mixture, and may be used as an undercoat by forming a single layer or a plurality of layers. It may be a two-layer structure or the like relating to the combination of ceramic materials.

As the thermal spraying method, any thermal spraying method using plasma, a combustion flame of a combustible gas or explosive energy of a combustible gas, an arc by direct current electricity, or the like can be used.

(2) Formation of Composite Thermal Sprayed Film of Ceramic Powder and Vitreous Material as Top Coat The surface of the thermal sprayed film formed as an undercoat has appropriate roughness and pores unique to the thermal sprayed film. Therefore, by utilizing this feature, a thermal spraying material in which ceramic particles and a vitreous material are mixed is sprayed thereon as a top coat. Prior to this thermal spraying, the undercoat thermal spray coating is preheated to 200 to 500 ° C, and after the top coat is thermal sprayed, these films (composite thermal spray coating) are heated in an electric furnace at 400 to 850 ° C and 0.1 to 5 ° C. When heated for a long time, the degree of bonding between the undercoat and the top coat is improved, and the pores and bubbles existing in the top coat disappear, resulting in a dense composite sprayed coating. It is more effective to perform such a heat treatment in a reduced-pressure atmosphere.

In the top coat sprayed coating, ceramic powder is used as the particles for strengthening the dispersion, and it is preferable to use the following compounds alone or in combination of two or more. (A) Oxide ceramics Al ₂ O ₃ , TiO ₂ , MgO, ZrO ₂ , Ta ₂ O ₅ , Nb ₂ O ₅ , SiO ₂ , Cr
₂ O ₃ , NiO (B) Non-oxide ceramics WC, Cr ₃ C ₂ , NbC, TaC, HfC, MoC, TiC, ZrC and other carbides NiB ₂ , CrB ₂ , W ₂ B ₅ , TiB ₂ , ZrB ₂ , NbB ₂ , TaB ₂ and other borides TiN, VN, NbN, TaN, HfN, ZrN, BN, Si ₃ N ₄ , CrN and other nitrides The dispersion strengthening ceramic powder is a glassy material that is a matrix. Because it is dispersed inside,
The average particle size is preferably from 1 to 80 μm. If the average particle size is larger than 80 μm, the bondability with glass is poor, and if it is smaller than 1 μm, the uniform dispersibility is poor.

In the present invention, one of the features of the vitreous sprayed coating serving as the top coat (in the present invention, the vitreous coating includes so-called "enamel") is its linear expansion coefficient. Is in the range of 4 to 14 × 10 ⁻⁶ / ° C. The reason for this is
Steel substrates generally have a coefficient of linear expansion of 10 to 18 × 10 ^−6.
/ ° C, and the thermal expansion coefficient of the thermal spray coating as an undercoat formed on the surface of the metal is, for example, a metal having a large value (23.5 × 10 ⁻⁶ / ° C) such as Al. The thermal spray coating has a small value because it contains oxides and pores, it does not peel off even after a thermal change after film formation, and such a thermal spray coating is not linear for the top coat formed on it. It will play a buffering role in the expansion properties. In addition to the function of the undercoat, if the linear expansion coefficient of the vitreous material constituting the top coat is selected to be in the range of 4 to 14 × 10 ⁻⁶ / ° C., both coats may peel off or the top coat may be cracked. Is no longer generated.

In the present invention, the linear thermal expansion coefficient of the above-mentioned glassy sprayed coating used as a top coat is 4 to 14 × 10 ^-6 /
Another reason for limiting to the range of ° C is that most of the ceramic particles dispersed and mixed in the vitreous matrix of the composite sprayed coating are within this linear expansion coefficient range. This is because, even during use, the fused state of the contact interface between the vitreous material and the ceramics is maintained even if the temperature is suddenly changed, and the occurrence of micro cracks can be prevented.

Further, the vitreous material constituting the matrix of the above-mentioned vitreous thermal spray coating has a linear expansion coefficient of 4 to 14 × 10
^-6 / Yet another reason is limited to ° C., the vitreous material of the linear expansion coefficient of less than 4 × 10 ^-6 / ° C. does this after it is difficult to deposited by thermal spraying, can even deposition Even if a slight change in temperature occurs, a fine crack is generated in the vitreous material portion. On the other hand, the vitreous material having a linear expansion coefficient ^exceeding 14 × 10 ⁻⁶ / ° C. is industrially difficult to produce.

Adjustment of the linear expansion coefficient of the above-mentioned vitreous material, enamel and the like is performed mainly by controlling the contents of SiO ₂ , K ₂ O, Na ₂ O and Li ₂ O. In general, as the SiO ₂ content increases, the coefficient of linear expansion decreases, and as the alkali component increases, the coefficient increases.

Another feature of the vitreous spray coating constituting the top coat of the present invention is that the melting point of the vitreous material is 500 to 75.
Use in the range of 0 ° C. Vitreous materials in this temperature range have good compatibility with the undercoat sprayed coating preheated to 200 to 500 ° C, and also soften well when the topcoat is heated to 400 to 850 ° C after thermal spraying. The pores remaining immediately after the thermal spray coating is formed can be eliminated. Here, the melting point of the vitreous material is 500
Glass below ℃ cannot be used in molten metal, while glassy material above 750 ℃ has a linear expansion coefficient of 4 × 10 ^-6 / ℃
Therefore, it is not suitable as a vitreous material used in the present invention.

In the present invention, a compound having the following chemical composition can be advantageously used as a matrix material (vitreous material) of a vitreous spray coating to be a top coat. (a) Vitreous material: Na ₂ O, K ₂ O, BaO, B ₂ O ₃ , SiO ₂ , MgO
, As a main component _{CaO, PbO, Li 2 O,} SrO, and SnO ₂ (b) enamel material: natural feldspar, natural silica, soda ash
(Na ₂ CO ₃ ), borax (Na ₂ B ₄ O ₇ ), etc. as raw materials, SiO ₂ , Al ₂ O
₃ , B ₂ O ₃ , CaF, Na ₂ O, K ₂ O as main component, with minor components such as CoO, MnO, NiO, TiO ₂ , ZnO added

The particle size of the above-mentioned glassy material for thermal spraying can be in the range of 10 to 150 μm.
Particularly, those having a thickness of 30 to 90 μm are suitable. It has a particle size of 10
If it is smaller than μm, the probability of being overheated and scattered in the thermal spraying heat source is high, and the rate of adhering as a film (yield) is small. On the other hand, particles larger than 150 μm are poorly mixed with ceramic particles and have large and many pores when formed, so that even if combustion is performed, it takes a long time to eliminate the pores, leading to an increase in cost. This is not a good idea.

In the present invention, the mixing ratio of the ceramic powder and the vitreous material in the ceramic-reinforced glassy thermal spray coating used as the top coat is such that each is in the range of 5 to 95 by weight%. The specific mixing state is shown in FIGS. 1 (a), 1 (b) and 1 (c). That is, FIG.
Means that the ceramic particles are a vitreous material (matrix)
This shows a state in which the particles are uniformly dispersed therein. Fig. 1 (b)
Are films with different contents of ceramic particles (3-1, 3-2,
3-3) shows a film with stepwise variable dispersion obtained by changing stepwise.The content of ceramic particles is smaller on the surface side of the film, but if necessary, the structure is reversed. You can also. FIG. 1 (c) shows a gradual variable dispersion state in which the content of the ceramic particles of FIG. 1 (b) is continuously changed apparently, and also in this case, the content of the ceramic particles is also reduced. A structure having an inverse composition can be used. In the drawings, reference numeral 1 denotes an object to be processed, 2 denotes an undercoat, 3 denotes a sprayed top coat, 4 denotes ceramic particles, and 5 denotes a vitreous material.

The characteristics of the top coat thermal spray coating (vitreous thermal spray coating) formed in this way are mainly characterized by the fact that the vitreous material mainly prevents the penetration of corrosive components such as moisture, acid, alkali, seawater and the like, and the ceramic particles are formed of bone. When the material is used at a high temperature (450 to 630 ° C.) such as a roll in a hot-dip plating bath, the vitreous material is softened and the abrasion resistance is significantly reduced. However, at such a temperature, the ceramic particles have the same high strength as at room temperature, and the composite sprayed coating as a whole exhibits excellent wear resistance. Also, when the top coat sprayed coating is heated to a temperature equal to or higher than the melting point of the vitreous material, it has an effect of preventing the flow of the molten glass. The ceramic particles used in the present invention exhibit excellent corrosion resistance to corrosive components and molten metals, and can be used in a stable state for a long time.

In the present invention, the formation of the composite sprayed coating is as follows:
It can be applied using a thermal spraying method that uses the combustion flame of plasma and flammable gas as a heat source. If necessary, after forming the film, heating it in an electric furnace at 400 to 850 ° C for 0.1 to 5 hours will result in a dense undercoat. A top coat with good adhesion to

The composite sprayed coating obtained by combining the undercoat and the topcoat after forming the film has a thickness of 10 to 1000 μm.
m. If the thickness is less than 10 μm, the function as a composite spray coating will be insufficient.
When the thickness is more than 1000 μm, it is not advisable to take a long time to form the film even if the function as the composite sprayed film is maintained, which increases the cost.

As described above, the top coat glassy thermal spray coating is made by mixing ceramic powder and vitreous material powder in a weight ratio of 5 to 95% and performing thermal spraying. If the difference is large, for example, when WC (specific gravity 15) and vitreous powder (specific gravity 4.5) are mixed and sprayed, the mixing ratio of the two in the coating is considerably different from that in the powder state. According to our experiments, WC (50
wt%) and vitreous material powder (50wt%), and then sprayed, this coating shows WC on the undercoat side.
Occupies more than 90% of the film surface, while the vitreous material is
It has been confirmed that it is in a state of 0%.

From the above, in the present invention, the term “top coat” refers to a ceramic-reinforced glassy thermal sprayed coating, and the mixing ratio of ceramic powder and glassy powder is preferably 5 to 95% by weight as a material for thermal spraying. It can be used for forming a natural film. If the mixing ratio of the ceramic powder is less than 5%, the function as an aggregate is small, and if it is 95% or more, the vitreous function tends to be unable to be sufficiently exerted.

[0028]

【Example】

Example 1 In this example, the optimum thickness of a top coat thermal spray coating (mixed thermal spray coating of ceramic powder and glassy material) formed on an undercoat thermal spray coating of various materials was investigated. 1. The base metal to be tested, SUS410L (ferritic stainless steel), was
Finished and used for length 200mm. 2. Thermal spraying material for undercoat and film thickness 2-1 80 wt% Ni-20 wt% Cr was applied to a film thickness of 100 μm by plasma spraying. 2-2 After applying 80wt% Ni-20wt% Cr to a film thickness of 50μm by plasma spraying, 60wt% Al ₂ O ₃ -40wt% TiO ₂
Was applied to a film thickness of 100 μm by a plasma spraying method to form a two-layer structure. 2-3 was constructed in a thickness 100 [mu] m by _{73wt% Cr 3 C 2 -20wt%} Cr-7wt% Ni the high-velocity flame spraying method. 2-4 88wt% WC-12wt% Co was applied to a film thickness of 100μm by high-speed flame spraying. 3. Spray material and coating the topcoat thickness _{3-1 10wt% B 2 O 3 -25wt} % Na 2 O-5wt% CaO -60wt% Si
O ₂ 3-2 11 wt% B ₂ O ₃ -14 wt% Li ₂ O-3 wt% Al ₂ O ₃ -2 wt%
After thorough mixing so that the 50% SrO -70wt% SiO ₂ the glassy Al ₂ O ₃ powder in a weight ratio, by plasma spraying, 10 [mu] m on the undercoat sprayed coating, 50 [mu] m, 100 [mu] m, 250 mu
m, 500 μm, 750 μm, 1000 μm, 1500 μm, 2000 μ
A composite sprayed coating was applied by spraying to a thickness of m. Then, it was heated in an electric furnace at 850 ° C. × 1 hour.

Evaluation Method The test piece completed in the above process was heated in a 600 ° C. electric furnace for 15 minutes and then put into 25 ° C. water and cooled, as one cycle. This operation was repeated 20 times to generate a top coat. The presence or absence of cracks and peeling was visually observed.

Test Results Al ₂ O ₃ powder and 10 wt% B ₂ O ₅ -25 wt% Na ₂ O-5 wt% CaO-60
Table 1 shows the test results of the composite thermal spray coatings mixed with wt% SiO ₂ powder.
Al ₂ O ₃ powder and 11 wt% B ₂ O ₂ -14 wt% LiO ₂ -3 wt% Al ₂ O
The test results of _{3 -2wt%} SrO _-70wt% SiO ₂ composite sprayed coating powders were mixed as shown in Table 2, respectively. As is clear from the results, in the case where the composite thermal spray coating formed by mixing the Al ₂ O ₃ powder and the vitreous material has a thickness of 10 to 1000 μm, there is no generation of minute cracks even in 20 cycles of heating-cooling, All were in a healthy state regardless of the type of the undercoat sprayed coating material. On the other hand, the sprayed coating thickness is 1500-2000μ
In the case of m, minute cracks occurred, and the number of cracks increased and increased as the film thickness increased. From the above results, the composite thermal spray coating using two types of glassy material shows a common tendency, the thickness of the composite thermal spray coating containing the glassy material of the present invention, the range of 10 ~ 1000μm is suitable. Turned out to be.

[0031]

[Table 1]

[0032]

[Table 2]

Example 2 In this example, the preheating temperature of the undercoat thermal spray coating, the properties of the vitreous (top coat) thermal spray coating formed thereon, and the characteristics of the composite thermal spray coating by heat treatment after the formation of the vitreous thermal spray coating are described. Was investigated by a salt spray test. 1. Test Base Material The same material as in Example 1 was processed into dimensions of 50 mm in width, 100 mm in length, and 5 mm in thickness, and a thermal spray coating was formed on the entire surface. 2. Thermal spraying material for undercoat and its thickness of 13% Cr steel (JIS G4305 SUS 405 equivalent) were used as thermal spraying material, and undercoat sprayed film was formed by plasma spraying to a thickness of 150 μm. 3. Thermal spray material (vitreous material) for top coat and its thickness (1) 30 wt% SiO ₂ −21.0 wt% B ₂ O ₃ −17 wt% LiO ₂ −5.0 wt
% TiO ₂ −5.0 wt% ZnO −4.0 wt% ZrO ₂ −40 wt% SrO −3.
0 wt% SnO ₂ −3.0 wt% Al ₂ O ₃ −2.5 wt% BaO (2) 40.0 wt% SiO ₂ −27.0 wt% B ₂ O ₃ −18.0 wt% LiO ₂ −4.0
wt% SrO -3.0 wt% CaO -2.0 wt% Al ₂ O ₃ -2.0 wt% TiO
₂ −2.0 wt% ZnO −2.0 wt% ZrO ₂ −2.0 wt% SnO ₂ −2.5 w
to t% BaO said vitreous material (matrix material), a material obtained by adding and mixing Al ₂ O ₃ particles (10 to 30 [mu] m) so that 20 wt% and the spray material, was constructed this to 250μm thick. 4. Preheating temperature of undercoat sprayed coating Preheating was performed in an electric furnace from room temperature (no preheating) to 800 ° C. 5. Post-treatment of top coat sprayed coating Heated from room temperature (no post-treatment) to 900 ° C in an electric furnace, but heated from room temperature to 500 ° C for 10 hours, 550 ° C to 700 ° C for 3 hours, and higher temperature for 0.5 hours Of heating.

Evaluation method The properties of the composite coatings subjected to the various preheating and post-heating treatments described above were subjected to a continuous test for 96 hours by the salt spray test method according to JIS Z2371 (1988), and the top coating was determined based on the area of iron rust generated on the sprayed coating surface. The denseness of the thermal spray coating was evaluated.

Test Results FIG. 2 shows the rusting state of the thermal spray coating in relation to the preheating temperature and the post-treatment temperature. As is evident from these results, when the preheating temperature of the undercoat sprayed coating is 200 ° C or less and the post-treatment temperature is 400 ° C or less, red rust occurs over the entire coating and numerous pores are formed in the topcoat vitreous sprayed coating. Was found to be present. Preheating temperature is 500 ℃
When the post-treatment temperature is in the range of 400 ° C or less, although the generation of red rust is small, the preheating temperature is high, and a large number of bubbles are generated in the glassy sprayed coating of the top coat due to the abrasion due to the oxidation of the undercoat sprayed coating. Had lost sex. On the other hand, such a tendency is that the post-treatment temperature is 400-850.
When the temperature was increased to ° C., the generation of bubbles increased.

On the other hand, when heated to a preheating temperature of 200 to 500 ° C., even at a post-treatment temperature of 200 ° C. or less, the glassy sprayed film of the top coat is smooth and the generation of red rust is small.
(Less than 0.1 point per cm ² ). And, even if the preheating temperature is 200 ° C or less,
At temperatures of up to 850 ° C., the pores of the glassy thermal spray coating of the top coat disappear, and the generation of red rust is small. In particular, no red rust was observed in the coating in the range where the precoat temperature of the undercoat was 200 to 500 ° C and the post-treatment temperature of the topcoat was 400 to 850 ° C. (Especially in the top coat sprayed coating). The above results are common to the two types of vitreous components tested. FIG. 2 shows the optimum preheating temperature range for forming the composite sprayed coating of the present invention and the optimum heat treatment temperature range after forming the coating from the above results by oblique lines.

Example 3 In this example, a steel member (specimen) having a composite sprayed coating according to the present invention was immersed in a molten zinc bath, and its molten zinc resistance was investigated. At the same time, the test specimen pulled up from the molten zinc bath was put into water at 20 ° C., and the thermal shock performance was also evaluated. 1. 1. Base material to be tested Same as in Example 1. 2. Thermal spray material for undercoat and film thickness The type of thermal spray material and the film thickness are the same as in Example 1. Vitreous spray material and its coating topcoat thickness _{27wt% B 2 O 3 -18wt%} LiO 2 -4wt% SrO -3wt% CaO -2
_{wt% Al 2 O 3 -2wt%} TiO 2 -2wt% ZnO -2wt% ZrO 2 -2
wt% SnO -2.5 wt% BaO -40wt % SiO 2 Al 2 O 3 in the vitreous, Cr ₃ C _2, NiB, a mixture may be added 50 wt% TiN powder, respectively as a spray material,
The undercoat was applied to a thickness of 300 μm on the sprayed coating.

Evaluation method Zinc bath conditions: Zn bath containing 0.1 wt% Al 480 ° C. Immersion time in zinc bath: 24 hours, immersion in water at 20 ° C. as one cycle, 10 coatings after the test Visual observation of the appearance of
The presence or absence of cracks and peeling of the coating was investigated. As a comparative example, a film obtained by immersing a coating without forming a vitreous spray coating in a zinc bath under the same conditions as in the case of a top coat and repeating a cycle of throwing in water 10 times was tested.

Test Results The test results are summarized in Table 3. As is clear from the results, in the comparative example (No. 5) in which the composite thermal spray coating containing the vitreous material was not formed, the adhesion of the molten zinc was large, and in particular, the metallic undercoat thermal spray coating (80 wt.
% Ni-20wt% Cr), was severely eroded by zinc. Also, unlike 60 wt% Al ₂ O ₃ -40 wt% TiO ₂ , even though it does not react with zinc itself, molten zinc penetrates through the pores in the film and erodes the metal film in the lower layer. did. On the other hand, the composite thermal spray coating including the glassy thermal spray coating in which the ceramic powder is dispersed as the reinforcing dispersant according to the present invention (in the case of Nos. 1, 2, 3, and 4) has no relation to the type of the undercoat thermal spray coating. In all cases, the adhesion of zinc was slight or almost no. It is considered that such performance is due not only to the vitreous material but also to the fact that the ceramic particles added therein do not react with the molten zinc and are extremely dense and completely prevent the molten zinc from entering the inside. In addition, immediately raise the zinc bath from 480 ° C.
The composite sprayed coating was sound even when poured into water at 20 ° C.

[0040]

[Table 3]

Example 4 In this example, the coating of the present invention was immersed in a molten zinc-aluminum alloy bath and a molten aluminum bath, and its molten metal resistance and thermal shock resistance were investigated. 1. 1. Base material to be tested Same as in Example 1. 2. Thermal spray material for undercoat and film thickness The type of thermal spray material and the film thickness are the same as in Example 1. Thermal spray material for top coat and its film thickness The type of glassy thermal spray coating, the type and mixing ratio of ceramic powder dispersed and added thereto, and the film thickness are the same as in Example 3.

Evaluation method Immersion conditions: 45 wt% Zn-55 wt% Al 605 ° C. 8 wt% Si-92 wt% Al 680 ° C. In both baths, the test piece was immersed for 24 hours, and then put into water at 20 ° C. for 10 cycles. Repeated times. After the completion of the above test, the appearance of the film was visually inspected for the adhesion state of the molten metal and the presence or absence of cracks and peeling of the film. As a comparative example, a top coat was tested under the same conditions without forming a vitreous spray coating in which ceramic powder was dispersed and mixed, that is, only an undercoat spray coating.

Test Results The test results are summarized in Table 4. As is clear from the results, the thermal spray coatings of Comparative Examples (Nos. 9 and 10)
When immersed in a 45 wt% Zn-55 wt% Al alloy bath and an 8 wt% Si-92 wt% Al bath, the molten metal was eroded almost all over the first and second times. On the other hand, the composite sprayed coatings (Nos. 1 to 8) according to the present invention have little adhesion of the molten metal, and these metal coatings can be easily removed with a finger, and the composite coating surface of the removed portion has no effect. No abnormalities were observed. Further, cracking due to thermal shock was not visually observed in the composite film of the top coat.

[0044]

[Table 4]

Example 5 In this example, when the film of the present invention was immersed in a molten zinc bath and then pulled up, a thin zinc film adhered to the film. Although this zinc film can be easily peeled off mechanically, a method of chemically dissolving and removing the zinc film was studied. 1. 1. Base material to be tested Same as in Example 1. 2. Thermal spray material for undercoat and film thickness The type of thermal spray material and the film thickness are the same as in Example 1. Topcoat sprayed material and its coating thickness _{3-1 17wt% B 2 O 3 -12wt} % Na 2 O-5 wt% K 2 O -6 wt% Li
₂ O-4 wt% Al ₂ O ₃ -4 wt% SrO -52 wt% SiO ₂ 3 -26 26 wt% B ₂ O ₃ -18 wt% Li ₂ O-4 wt% SrO -2 wt% Al
₂ O ₃ -50 wt% SiO ₂ Al ₂ O ₃ , 92.5 wt% Al ₂ O ₃ -7.5 wt% Ti
As a thermal spraying material, a powder to which O ₂ , TiC, and TiB powders were added in an amount of 40 wt% was formed by thermal spraying on an undercoat film to a thickness of 150 μm. The test piece on which the undercoat film was applied prior to thermal spraying was heated to 250 ° C in an electric furnace in advance, and was heated in an electric furnace at 700 ° C for 30 minutes after thermal spraying.

Evaluation method The composite sprayed coating of the present invention formed as described above was treated at 480 ° C.
Immersed in a molten zinc bath for 24 hours, pulled up and cooled to room temperature, and then immersed in the next chemical for 24 hours to dissolve and remove zinc on the film, and to improve the chemical resistance of the film of the present invention. investigated. 5 wt% HCl 25 ° C. × 24 h 5 wt% NaOH 60 ° C. × 24 h As a comparative example, an undercoat sprayed coating having no top coat was tested under the same conditions.

Test results Table 5 summarizes the test results. As is evident from the results, in the case of the undercoat sprayed coating having no vitreous sprayed coating of the comparative example alone (No. 9), the zinc and the coating react even when immersed in the molten zinc bath, and the erosion phenomenon occurs. Appears, and a large amount of zinc adheres to the test piece pulled up from the bath. When the test piece in such a state is immersed in 5 wt% HCl and 5 wt% NaOH, zinc is eluted while generating hydrogen gas in any case. This is because zinc is an amphoteric metal that chemically reacts with both acids and alkalis. On the surface where zinc was dissolved, the film eroded by zinc was exposed, and the film was lifted up by the action of hydrogen gas generated at the time of dispensing of zinc, leading to peeling. Also, it was observed that the action of HCl was strongly exhibited. On the other hand, the composite sprayed coating having a top coat comprising the glassy material and the ceramic powder according to the present invention (Nos. 1 to 8) is not affected by the molten zinc, and when pulled up from the molten zinc bath, Thinly adhered zinc can be easily dissolved and removed with HCl and NaOH, and the removed surface shows no abnormality.
It was sound.

[0048]

[Table 5]

Example 6 In this example, the wear resistance of the composite sprayed coating of the present invention was investigated. 1. Base material to be tested Structural steel plate SS400 cut to a width of 50 mm, a length of 60 mm and a thickness of 5 mm was used. 2. Type and thickness of thermal spraying material for undercoating 88 wt% WC-12 wt% Co was used as the thermal spraying material, and the thickness was 150 μm by the constrained flame spraying method. 3. Types of thermal spraying material for top coat and its film structure 22 wt% B ₂ O ₃ -17 wt% Li ₂ O-4 wt% as vitreous material
SrO -3wt% Al ₂ O ₃ with -54wt% SiO _2, this Al ₂ O _3,
The mixture to which Cr ₃ C ₂ was added was sprayed by plasma spraying.
A composite film having the following structure was formed. 3-1 Structure of composite thermal spray coating Sprayed material with Al ₂ O ₃ and Cr ₃ C ₂ powder at 50wt% each in thickness of 150μm (uniform mixing and dispersion) Mixing of Al ₂ O ₃ and Cr ₃ C ₂ powder Applying a layer whose ratio is changed stepwise as follows to a thickness of 200 μm (stepwise variable dispersion) On the undercoat sprayed coating every 50 μm thickness (A) Ceramic powder / glassy = 95/5 (B) Ceramic powder / glassy = 50/50 (C) Ceramic powder / glassy = 20/80 (D) Ceramic powder / glassy = 95/5 While adjusting the amount of ceramic powder to be smaller in the upper part of the composite sprayed coating
It was applied to a thickness of μm. Although the maximum of the ceramic powder content of this film was 95 wt% and the minimum was 5 wt%, the outermost layer was partially scattered with 100% vitreous. (Gradual variable dispersion) The above-mentioned top coat spray coating is applied after preheating the undercoat spray coating to 300 ° C, and then 650 ° C ×
By performing a heat treatment for 5 hours, a composite spray was obtained.

Evaluation method Using an Ogoshi type abrasion tester, a test piece having the above-mentioned various MCrAlX alloy spray-coated was placed horizontally, and a diameter of 30 m was placed thereon.
m, the SiC paper thickness 3mm of the contact portion between the thermal spray coating is brought into contact with a disc that wound, while the load pressure on the 0.12 kgf / mm ² thereof, is rotated at a speed of 1 second 0.6 m, When the total rotation speed reached 300 m, the test was stopped and the determination was made by measuring the weight change of the test piece. FIG. 3 shows a test piece.
This shows the state of contact between the steel disk 31 and the steel disk 32 that makes a rotational movement.The coating of the present invention and the coating of the comparative example are located on the upper part 33 of the test piece and come into adjustment contact with the SiC paper. ing.

Test Results The test results are summarized in Table 6. As is clear from the results, the coating (No. 7) of the comparative example has a large weight loss due to abrasion, and decreases sharply as the test time (contact time with the rotating disk) increases. On the other hand, the coating of the present invention generally has a small weight loss regardless of the mixed state of the ceramic powder. In particular, a composite sprayed coating having a higher mixing ratio of ceramic powder has better wear resistance. However, in the case of the composite sprayed coating (No. 3, 6) in which the ceramic powder concentration is changed stepwise (No. 2, 5) or gradually, the initial wear is relatively large, but as the time elapses, The amount has shown a tendency to decrease. As can be seen from these test results, it was confirmed that the composite sprayed coating obtained by dispersing and mixing hard ceramic powder in a vitreous material had better wear resistance than the composite sprayed coating not containing ceramic powder. Was.

[0052]

[Table 6]

[0053]

As described above, a thermal spray coating made of metal, ceramics and these components is used as an undercoat, and a glassy composite thermal spray coating containing ceramic powder is formed as a top coat while preheating the same.
The heat-treated composite sprayed coating of the present invention has no pores in the coating due to the presence of the glass component, and the addition of the aggregate component made of ceramics, in addition to the properties of corrosion resistance, thermal shock resistance, and wear resistance, Demonstrates excellent performance in resistance to molten metal. Therefore, when the composite sprayed coating of the present invention is used as a member for hot-dip metal plating, it is not only improved in productivity and quality of plated products due to longer life, but also excellent in chemical resistance. There is an advantage that it becomes easy.

[Brief description of the drawings]

FIG. 1 shows a cross-sectional structure of a composite thermal spray coating used in the present invention.

FIG. 2 is a graph showing a relationship between a preheating temperature of an undercoat thermal spray coating and a heat treatment temperature after formation of a top coat vitreous thermal spray coating to obtain a preferable composite thermal spray coating.

FIG. 3 schematically shows a state of a wear test of a thermal spray coating of a top coat.

[Description of Signs] 1 Steel base material 2 Undercoat thermal spray coating 3 Top coat vitreous thermal spray coating 4 Ceramic powder particles 5 Vitreous material component 31 Steel base material 32 Rotating member wrapped with SiC paper 33 Thermal spray coating W Rotating member Symbol indicating that load is being applied

Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) C23C 4/08-4/18

Claims (5)

(57) [Claims] 1. A metal, an oxide or non-oxide ceramic and a ceramic on a surface of a steel base material.
And any one selected from these cermets
An undercoat sprayed film with a film thickness of 30 to 750 μm formed by spraying the above, and a 5% to 95% by weight
Oxide or non-oxide ceramic powder
And a vitreous material that forms a matrix
A steel member having a composite thermal spray coating, comprising: a ceramic reinforced glassy thermal spray coating having a thickness of 10 to 1000 μm ; 2. The above-mentioned glassy sprayed coating has a ceramic powder dispersed in a glassy material serving as a matrix, in which the dispersion form is one of a uniform dispersion, a stepwise variable dispersion, and a gradually variable dispersion. The steel member according to claim 1, wherein: 3. The thermal spray coating according to claim 1, wherein the thermal spray coating comprises SiO ₂ , Na
₂ O, K ₂ O, B ₂ O ₃ , Al ₂ O ₃ , Li ₂ O, CaO, MgO, Ti
The matrix is a vitreous material containing at least two oxides selected from O ₂ , ZnO, ZrO ₂ , SnO ₂ , SrO, BaO, and CoO as a matrix. The steel member according to claim 1, wherein the steel member has a temperature of 7 to 14 × 10 ⁻⁶ / ° C and a melting point of 500 to 750 ° C. 4. A steel base material having a surface selected from the group consisting of metals, ceramics and cermets thereof.
At least one kind of material is sprayed to form an undercoat sprayed coating, and then a glassy material containing ceramic particles dispersed therein is sprayed on the sprayed coating to form a composite sprayed coating. A method for producing a steel member having a composite sprayed coating, comprising heating at a temperature of 400 to 850 ° C for 0.5 to 10 hours. 5. A steel base material having a surface selected from the group consisting of metals, ceramics and cermets thereof.
Spraying more than one kind of material to form an undercoat sprayed film, and then applying the undercoat sprayed film at 200 to 500 ° C
Forming a composite thermal spray coating by spraying a vitreous material containing ceramic particles dispersed therein while heating the composite thermal spray coating, and thereafter heating the composite thermal spray coating at a temperature of 400 to 850 ° C. for 0.1 to 5 hours. A method for producing a steel member having a composite thermal spray coating.