JP3403521B2 - Melting-resistant metal member 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 member for hot-dip metal having a composite coating and a method for producing the same, and in particular, it is used in various fields such as hot-dip galvanizing, hot-dip zinc-aluminum alloy plating, and hot-dip aluminum coating. This is a proposal for the technology of forming a composite film on the surface of molten metal members such as rolls, bearings, sleeves, bushes, and metal fittings for plating amount adjustment.

[0002]

2. Description of the Related Art Since galvanized layers such as hot-dip galvanizing, hot-dip aluminum coating, and hot-dip zinc-aluminum alloy plating exhibit excellent rust and corrosion resistance, they have long been used in automobiles, aircraft, vehicles, construction, home appliances. It is used for parts such as products, and is still one of the surface treatments that still plays a major role.

Hot-dip galvanized steel sheets that are produced in large quantities are often produced by continuous hot-dip galvanizing equipment. This continuous hot dip galvanizing device includes a sink roll immersed in a plating bath, a support roll arranged near the surface of the plating bath, and a guide roll for guiding the plated steel sheet after passing through these rolls. Members for molten metal such as These members are
Since it is immersed in the plating bath or installed in a place where molten zinc is likely to scatter and adhere, and since it is used so as to come into contact with the high temperature steel plate to which molten zinc adheres, (1) Corrosion by molten zinc occurs Difficulty, (2) Hard to wear even when it comes into contact with the strip material (steel plate), (3) Easy to remove adhered molten zinc and easy to perform maintenance inspection, (4) Long life and low durability as a plating member. Performance is required such as cost, and (5) well withstanding thermal shock when immersed in a hot molten zinc bath.

In order to meet such demands, taking a film for sink rolls as an example, (1) Japanese Patent Publication No. 56-39709, Japanese Patent Publication No. 58-11507, and Japanese Patent Publication No. 59-153875. JIS H8303 (197) 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
A spray-formed oxide ceramics film composed of ZrO ₂ and Al ₂ O ₃ , as disclosed in Japanese Patent No. 181 and Japanese Patent Publication No. 27290/1992, (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 borides with a cermet spray coating formed by coexisting a metal such as Cr, Ni, Co, (4) As described in JP-A-4-13857.
A combination of the techniques of (1) and (3), (5) Further, Japanese Patent Publication No. 52-22934, in which a molten metal is welded, and W
Japanese Patent Application Laid-Open No. 53-128538, in which a thermal spray film of Cr is formed, Japanese Patent Application Laid-Open No. 4-165058 in which a thermal spray film of Cr is formed, and the like are proposed.

The inventors of the present invention have conducted research and development on similar techniques to the above techniques. For example, (6) Japanese Patent Application
No. 63-49846 (Japanese Patent Laid-Open No. 1-225761), WC cermet contains 5 to 28% of Co and has a porosity of 1.8%.
% Or less, a thermal spray coating with a film thickness of 0.040 to less than 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 formed by a low pressure plasma spraying method, (8) Japanese Patent Application Flat 1
-54883 (JP-A-2-236266), 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) Jpn. Pat. Appln. 1-124010 (Kaikaihei 3-63565
No.), a coating formed by forming Cr ₃ O ₃ by a chemical densification method on a cermet sprayed coating mainly composed of carbide,
(10) Japanese Patent Application No. 2-201187 (Japanese Patent Application Laid-Open No. 4-88159), in which a part of the carbide sprayed coating is changed to boride by boride treatment, (11) Japanese Patent Application No. 3-31448 ( JP-A-4-254571), in which molten zinc resistance is improved by heat-diffusing Al or Al-Zn alloy into various carbides, borides or cermet spray coatings thereof, (1
2) In Japanese Patent Application No. 3-31448 (Japanese Patent Application Laid-Open No. 4-254571), Al or Al-
(13) Japanese Patent Application No. 3-222425 (Japanese Patent Laid-Open No. 4-358055) in which Zn is diffused and permeated, and a non-oxide ceramic powder or a powder obtained by mixing a metal with Al is added to Al or Al- (14) Japanese Patent Application No. 3-213143 (JP-A-5-33113), which is formed by using a thermal spray material containing a Zn alloy.
No.), a non-oxide ceramic powder or a powder obtained by mixing a metal with the non-oxide ceramic powder is added to an Al-Fe alloy or Al-Fe.
-Spray coating formed by using a spray material containing Zn alloy, (15) Japanese Patent Application No. 3-266874 (Japanese Patent Laid-Open No. 5-78801)
Has proposed various techniques and coatings 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, in recent research conducted by the inventors, it has been found that there are still problems to be solved regarding the molten metal resistance of the above-mentioned thermal spray coating. . That is, (1) The sprayed coating formed in the atmosphere always contains pores and oxides are mixed. Therefore, even if the thermal spray coating material is a substance that does not cause a metallurgical reaction with the molten metal,
Molten metal penetrates inside through these pores and reacts with the base metal, peeling off and destroying the film from the root. (2) Metals such as molten aluminum that have a small oxide formation energy are oxides contained in the coating (those that are directly contained in the coating after the thermal spray material is oxidized in the thermal spray heat source). In order to reduce, the pores are expanded, while the metal produced by the reduction also causes a metallurgical reaction to cause a volume change and destroys the film. (3) Carbide cermet represented by WC-Co is used as a spray coating for molten metal, but the molten metal adheres to the metal components contained in the coating or reacts metallurgically. As a result, sticking of the dross component is promoted, and finally the quality of the plated steel sheet is deteriorated. (4) Since all thermal spray members used in the molten metal bath are used in a high temperature environment, it is necessary that they have heat resistance and strong resistance to thermal shock.

An object of the present invention relates to a surface coating for coating the surface of a member for molten metal resistant, which is a composite modified thermal spray coating excellent in resistance to peeling and destruction of the coating, and also excellent in heat resistance and impact resistance. Is to propose. Another object of the present invention is to propose a technique that effectively contributes to the improvement of the quality of plated steel sheets.

[0008]

[Means for Solving the Problems] As a result of intensive studies aimed at achieving the above-mentioned purpose, the inventors found that the problems (1) and (2) above do not react with the molten metal on the surface of the thermal spray coating. The above can be solved by making the substance non-porous.
Regarding the problem of (3), we decided to coat the surface of the thermal spray coating with a substance that does not practically cause metallurgical reaction with molten metal, and further, in addition to the characteristics of (1) to (3) above, excellent heat resistance It is important to impart a thermal shock resistance to that, and therefore, in the present invention, a Co-based alloy-based fusing film is formed on the surface of the base material in order to firmly bond the thermal spray coating to the steel base material metallurgically. In some cases, we have found that it is more effective.

The present invention developed based on such knowledge provides (1) a Co-based alloy sprayed coating as a first layer on the surface of a steel substrate, and a carbide sprayed coating on the first layer. The second
The second layer of the carbide-based thermal spray coating is provided as a layer, and the thermal spray coating is a halogenated chlorinated gas containing hydrogen gas.
By heat treatment at 600 to 1100 ℃ in mug gas for 1 to 20 hours,
The reaction between the deposited metallic chromium and the carbon in the thermal spray coating
The Cr ₂₃ C ₆ type chromium carbide produced by
Having a modified layer formed by coating and impregnating the inside of the membrane pores
Moreover, the modified layer is further formed after the heat treatment,
In air, inert gas, vacuum or carburizing atmosphere
At 600-1000 ℃ for 0.5-10 hours
Includes those in which residual metal chromium is also changed to Cr ₂₃ C ₆ type carbide
It is a member for molten metal resistance, characterized in that Co
The base alloy spray coating is made of a Co base alloy having a thickness of 30 to 500 μm and a Co base alloy in which carbide particles are dispersed. The above-mentioned carbide-based sprayed coating has a thickness of 30 to 300 μm,
MnC, FeC, NiC, CoC, SiC, WC, MoC, BC, CrC, NbC, Ta
One or more carbides selected from C, HfC, ZrC and TiC, or one selected from these carbides and Co, Ni, Cr 1
It consists of a carbide cermet consisting of a mixture with one or more metals.

(2) First, a Co-based alloy is sprayed on the surface of the steel base material to form a Co-based alloy sprayed coating, and then a carbide or carbide cermet sprayed coating is further formed on this sprayed coating. Then, these thermal sprayed coatings were subjected to 600 to 1 in a chromium halide vapor generating atmosphere containing hydrogen gas.
100 ° C., then heated for 1 to 20 hours, Cr ₂₃ C ₆ type carbide chromium precipitated by reactions such as the free carbon of the activated metallic chromium particles and thermal spray coating in which occurs during the treatment atmosphere by the hydrogen reduction reaction at the time of heating Is formed on the surface of the carbide-based sprayed coating as well as in the pores to form a modified layer, and thereafter, with respect to the sprayed coating containing the modified layer, in the atmosphere,
600 ~ in inert gas, vacuum or carburizing atmosphere
Residual metal after post heat treatment at 1100 ℃ for 1 to 20 hours
This is a method for producing a member for molten metal resistant, characterized in that chromium is also changed to Cr ₂₃ C ₆ .

[0011]

The features of the present invention can be summarized as follows: Cr ₂₃ C ₆ type is formed on the surface and inside of the carbide-based sprayed coating, especially inside the pores, by the reaction between activated metal Cr and free carbon in the coating. It is intended to modify the film by forming chromium carbide to cover the surface of the film and to penetrate the inside of the film.

[0012] In this respect, generally used chrome charcoal
Compound spray material is Cr₃C₂Type carbide (orthorhombic), or
This and Cr₇C₃Mixed with type carbide (trigonal or orthorhombic)
It is a thing. This is the Cr used for modification in the present invention.
_{twenty three}C₆Type chrome carbide (cubic) has a big difference in characteristics
There is. That is, the conventional crystal type (Cr₃C₂, Cr₇C₃)
Rom has Cr contents of 86.8% and 91.0%, respectively. to this
On the other hand, Cr_{twenty three}C₆The type of chromium carbide is 94.3%,
The density is high and the hardness is high. Especially hydrogen gas
Metal chloride deposited by the reaction of bromine with chromium halides
Once the aluminum comes into contact with the free carbon, once Cr₃C₂, Cr₇C ₃ Raw
Even if it is done, this heat treatment atmosphere (600 to 1100 ℃)
In Cr_{twenty three}C₆Will be moved to. This invention is
This Cr_{twenty three}C₆-Type chromium carbide to modify the carbide spray coating
It has a feature in the complex technology.

In the present invention, the Co-based alloy for forming the first layer sprayed coating is, as a general commercial product name, such as MSFCo1, MSFCo2, MSFWC1 etc. defined in JIS H 8303 (1989) self-fluxing alloy spraying. Although a Co-based alloy called a stellite alloy can be used, it is also possible to disperse a carbide of 5 to 250 μm in these alloys. The composition of the Co-based alloy is Ni: 3% or less, Cr: 26
~ 30%, W: 0-12%, Mo: 0-5%, Fe: 3% or less,
It is preferable that C: 2.5% or less and Co: balance.

Further, as the carbide type thermal spraying material for forming the second layer thermal spray coating in the present invention, although detailed description will be given later, carbide powders (3) such as MnC, FeC, NiC, CoC, SiC, WC and BC can be used. ˜60 μm) is used. Incidentally, it is difficult to form a thermal spray coating with the above carbide alone, and even if a film can be formed, since the adhesion of the coating is weak and it is porous, the original function as a carbide thermal spray coating is exerted. Sometimes you can't. At this time, Co, Ni
Alternatively, when a metal element such as Cr is added and used as a cermet, the metal component is completely melted in the thermal spraying heat source and acts as a binder, which is effective in densifying the film and improving the adhesion. However, even if a film is formed using a cermet thermal spraying material in this way, there still exist about 0.5 to 5.0% of pores in the film, which impairs adhesion and wear resistance. Modification of the film is required.

In the present invention, at least carbon, preferably free carbon, must be contained in the above-mentioned carbide-based thermal spray material. Generally, this free carbon can be obtained by adding an excess of carbon when heating the metal and carbon or a carbon compound (CO, CmHn, etc.) in the production of various metal carbides. I mean,
This is because the presence of this free carbon is extremely effective in the present invention. That is, when the free carbon and the metal component in the form of fine particles are subjected to a contact reaction on the high temperature sprayed coating,
The metal component immediately becomes a carbide and strongly bonds to the spray coating component, and this spray coating deposits a new crystal type carbide generated by this reaction, that is, Cr ₂₃ C ₆ type chromium carbide, which is sprayed. It also penetrates into the inside of the coating (in the pores) and mutually bonds with the carbide particles that make up the thermal spray coating, significantly modifying the properties of the coating.

Next, the present invention will be described in more detail in accordance with a process for producing a member for molten metal resistance by forming a composite thermal spray coating comprising a first layer and a second layer on the surface of a steel base material. (1) Applying a thermal spray coating on the surface of the base material First, the surface of the steel base material is cleaned by blasting and roughened, and then the above-mentioned Co-based alloy spray coating is formed as the first underlayer. To do. Then, if necessary, this Co-based alloy sprayed coating may be subjected to a fusing treatment in which it is heated to a temperature of 980 to 1200 ° C. to improve the adhesion and the denseness of the coating.

Next, a carbide or carbide cermet coating is formed on the first layer Co-based alloy sprayed coating by a spraying method. The carbide-based thermal spray materials used here include (a) MnC, FeC, NiC, CoC, SiC, WC, MoC, MgC, B
Starting with any one or a mixture of two or more metal carbides such as C and CrC, which have a weaker carbon affinity than chromium, (b)
A metal carbide having a higher carbon affinity than chromium such as NbC, TaC, TiC, HfC, and ZrC, or (c), or a cermet thermal spraying material containing these carbides and a metal such as Co, Ni, or Cr or an alloy thereof is used.

As the thermal spraying method for forming the first and second layer coatings, a plasma thermal spraying method using electric energy as a heat source,
A laser spraying method, a flame spraying method using combustion energy of combustible gas as a heat source, or an explosive spraying method may be applied.

The thickness of each of the above thermal spray coatings is 30 to 30 for the Co-based alloy coating or the Co-based alloy coating in which the carbide is dispersed in the first layer.
The range of 500 μm is preferable, and 100 to 300 μm is particularly preferable. If the thickness is less than 30 μm, the function as the first layer film (adhesion to the substrate) is insufficient, and if it is more than 500 μm, it is economically disadvantageous. The thickness of the carbide or carbide cermet spray coating formed on the first layer as the second layer is preferably in the range of 30 to 300 μm, and particularly preferably 80 to 150 μm as the spray coating of the present invention. The reason for this is that if this coating is thinner than 30 μm, the Co-based alloy sprayed coating of the first layer cannot be completely coated, whereas if it is 300 μm or thicker, the coating thickness is less than that. This is because it does not change economically and is not a good idea.

(2) Heat Treatment in Chromium Halide Gas Containing Hydrogen Gas As described above, after the Co-based alloy sprayed coating, the carbide or the carbide cermet sprayed coating is formed on the surface of the steel substrate, these sprayed coatings are formed. Further, heat treatment is performed by heating in a chromium halide gas containing hydrogen gas at 600 to 1100 ° C. for 1 to 20 hours. The heat treatment in the chromium halide gas containing hydrogen gas can be performed by the apparatus shown in FIG. In Figure 1, 1 is Ni
Base alloy processing container, 2 chromium halide vapor introduction pipe, 3 argon gas introduction pipe, 4 hydrogen gas introduction pipe, 5
Is a gas discharge pipe, and each pipe is equipped with a valve capable of supplying or discharging gas. Further, the entire processing container is placed in an electric furnace and is heated from the outside, and 6 is a temperature measuring tube in the processing container.
Reference numeral 7 denotes an object to be processed, which can be installed on a shelf plate 8 using a porous alumina sintered plate.

This heat treatment is performed by first introducing argon gas, raising the temperature of the processing container to a predetermined temperature, and then introducing hydrogen gas and chromium halide gas. The hydrogen gas and the chromium halide gas react as in the following formula (1), and a large number of fine and chemically active metal chromium fine powders are deposited in this gas phase. CrX ₂ + H ₂ → Cr + 2HX (1) Here, X is a halogen element (Cl, F, I, Br, etc.). In some cases, the minute metallic chromium generated in the above formula (1) reaches the base material surface of the steel through the pores in the thermal spray coating, causes an alloying reaction, and strongly bonds, while a carbide or carbide cermet coating is formed. It reacts with the free carbon contained in it as shown in the following formula (2) to form the most thermodynamically stable Cr ₂₃ C ₆ type chromium carbide. _{23Cr + 6C → Cr 23 C 6} ... (2) It should be noted that, in the case of weak metal carbide of carbon affinity than Cr is,
It produces Cr ₂₃ C ₆ even if it contains no free carbon. For _{example, 23Cr + 6Fe 3 C → Cr} 23 C 6 + 18Fe ... (3) Fe generated in the equation (3), the Fe-Cr alloy reacts with Cr. Further, in the case of a carbide film in which Cr ₃ C ₂ or Cr ₇ C ₃ is mixed, thermodynamically stable Cr ₂₃ C ₆ type chromium carbide is produced.

Further, such heat treatment can be carried out by an apparatus as shown in FIG. In FIG. 2, 21 is a Ni-based alloy processing container, 22 is a hydrogen gas introducing pipe, 23
Is a gas discharge pipe, 24 is a temperature measuring pipe in the processing container, 25 is an object to be treated, 26 is a penetrant, and for example, when Cl is used as a halogen compound, the composition is 70% by weight of metallic chromium powder, 29% by weight of Al ₂ O ₃
%, Ammonium chloride 1.0 wt%. When hydrogen gas is flown into the processing container 26 and the temperature is raised to 330 ° C., ammonium chloride is decomposed and HCl gas is generated as shown in the following formula (4). NH ₄ Cl → NH ₃ + HCl (4) The HCl generated here reacts with the fine metal chromium powder in the penetrant to produce CrCl ₂ . Cr + 2HCl → CrCl ₂ (5) CrCl ₂ generated in the above formula (5) is a reaction gas of the above formula (1) due to the hydrogen gas introduced from the outside of the processing container to deposit fine metallic chromium in the container. , Which adheres to the thermal spray coating, bonds with the base material, fills the pores of the thermal spray coating, and forms a series of reactions such as Cr ₂₃ C ₆ formation. .

In the present invention, it is practical that the heat treatment is carried out at a reaction temperature with hydrogen of 600 to 1100 ° C. This is because if the temperature is lower than 600 ° C, the reaction of the formula (1) is slow, whereas if the temperature exceeds 1100 ° C, mechanical deterioration of the metal material that is the base of the thermal spray coating becomes serious.

The object of the present invention can be achieved if the amount of free carbon contained in the carbide spray coating is in the range of 0.01 to 5 wt%. Cr ₂₃ C ₆ with less than 0.01 wt% free carbon
If the amount of type chromium carbide produced is small, and if it is 5 wt% or more, it is difficult to apply the thermal spray coating of carbide and the film quality is deteriorated.

(3) Post heat treatment (2) Heat treatment in chromium halide gas containing hydrogen gas
Sprayed coating, especially on the surface of carbide sprayed coating
May remain unreacted chromium metal
In such a case, 600 to 600
Heat to 1000 ℃, Cr ₂O₃ To oxidize and physically remove
Or in an inert gas, vacuum or carburizing atmosphere
And heat to 600-1000 ℃ in Cr_{twenty three}C₆Anti-type chrome carbide
Complete the response.

FIG. 3 is a partial cross-sectional view of a member for molten metal resistance with a modified composite coating according to the present invention manufactured by the method as described above. 2 shows a cross-sectional structure of a modified thermal spray coating having excellent properties. In the figure (A), a Co-based alloy spray coating is formed as a first layer on a steel substrate, and a carbide spray coating is formed as a second layer on the first layer. 1 is a cross-sectional view of a composite thermal spray coating modified by heat-treating the thermal spray coating in a chromium halide gas containing hydrogen gas.
As shown in this figure, the fine metal chromium fine powder precipitated by the heat treatment passes through the pores existing in the film and reaches the surface of the steel base material, where an alloying reaction occurs and the first, second
The entire coating including the layers is strongly bonded by the action of the metallic chromium particles. (B) of the figure shows carbide particles dispersed in the Co-based alloy layer of the first layer coating, while (C) of the cross-sectional structure diagram when the amount of dispersion is increased toward the second layer coating,
It is a cross-sectional structure when carbide particles are uniformly dispersed in the Co-based alloy layer of the first layer coating.

In particular, in the pores in the vicinity of the sprayed surface of the second layer carbide-based sprayed coating, the filling with fine metal chromium fine powder and the reaction to form Cr ₂₃ C ₆ type chromium carbide rapidly proceed, and finally Cr _The surface is completely covered by the ₂₃ C ₆ type carbide. Here, 31 is a steel base material, 32 is a Co-based alloy sprayed coating, 33 is a carbide-based sprayed coating, 34 is a Cr ₂₃ C ₆ type chromium carbide layer formed on the carbide-based sprayed coating, and 35 is a Co-based alloy sprayed coating. Carbide particles dispersed in the coating, 36 is a layer showing a state in which particles constituting the Co-based alloy sprayed layer are metallurgically bonded by metal chromium particles, 37 is an alloy of the Co-based alloy sprayed layer and a steel base material It is a reaction layer.

[0028]

[Example] Example 1 SUS 403 stainless steel (50 x 100 x 5 mm
On top of t), 100 μ of MSFCo1 specified in JIS H 8303 as the first layer
m of thermal spray coating, and further, the following thermal spray coating of carbide cermet is formed on this first layer to a thickness of 150 μm, and then heat treated in hydrogen-containing chromium halide gas using the apparatus of FIG. Performed to produce Cr ₂₃ C ₆ type chromium carbide. Then, after that, the above-described post-heat treatment was performed to try to remove unreacted metallic chromium. (1) Test spray coating: 70 wt% Cr ₃ C ₂ -20 wt% Cr-9.7 wt% Ni-0.3 wt% C (2) Heat treatment conditions in chromium halide gas containing hydrogen gas; , Hydrogen gas 50ml per minute
Heat treatment was performed at 1000 ° C for 10 hours while flowing. (3) Post heat treatment conditions: The following conditions were combined. Atmosphere: Atmosphere, Argon gas, Vacuum, Carburizing gas Temperature: 600 ℃, 800 ℃, 900 ℃ Time: 0.5 h, 5 h, 10 h

Table 1 shows the X-ray diffraction test results at this time.
It was done. As is clear from the results shown in this table
In addition, the carbide of the coating immediately after plasma spraying is the same as the sprayed material
Cr₃C₂Which was oxidized in Ni and a plasma heat source.
Oxide of Cr (Cr₂O₃) Is recognized. This spray coating
Heat treatment in chromium halide gas containing hydrogen gas
And the carbide (Cr₃C₂) Is Cr_{twenty three}C₆Can change to
Is recognized. However, this heat treatment causes
Since a large amount of chromium particles belong to the Cr₃C ₂Ah
Ru Cr₃C₂Metals that do not react with free carbon contained in
Due to the presence of chromium particles, this diffraction peak is also observed.
It When these films are post-heat treated in various atmospheres,
The peaks of metallic chromium disappeared except in the atmosphere._{twenty three}
C₆It became only. In the post-heat treatment in air, unreacted metal
ROM reacts with oxygen to Cr₂O₃ Generated this Cr₂O₃ 
Has poor adhesion to the film and can be easily removed by buffing.
I was able to leave. Metallic vacuum in argon or vacuum
Rom Cr_{twenty three}C₆Changes to the joining of thermal spray coating and metallic chromium
Carbonaceous component (Cr₃C₂, Free carbon) and
Of the carburizing gas.
In the post heat treatment, the carbon content (CO) in the gas was changed to metallic chromium.
React and Cr_{twenty three}C₆It has changed to. Or more
Unreacted metallic chromium remaining on the thermal spray coating is
In air, in argon gas, in vacuum and in a carburizing atmosphere
By performing post heat treatment for 0.5 to 10 hours, C
r_{twenty three}C₆It turned out that it can be transformed into.

[0030]

[Table 1]

Example 2 SUS 403 steel (diameter 15 mm x length 200 mm) was obtained by the thermal spraying method.
After a film was formed on the surface of the rod-shaped test piece by the following steps, the durability was examined by immersing the film in a molten zinc bath. (1) After spraying 100μm thick Co-based alloy of MSFCo1, 1
00wt% WC was sprayed to a thickness of 100μm, then heat-treated at 930 ° C x 10h in chromium halide gas containing hydrogen gas, and then afterheat-treated at 800 ° C x 10h in the atmosphere. (2) After spraying 100μm thick Co-based alloy of MSFCo1, the coating is fused at 1050 ℃ and then 100wt% Cr ₃ C
₂ was sprayed to a thickness of 100 μm, then heat-treated at 930 ° C × 10h in chromium halide gas containing hydrogen gas, and then at 800 ° C × 10h in argon. (3) 150 μm of Co-based alloy with 10 wt% of TiC mixed with MSFCo1
After spraying thick, the coating is fused at 1050 ° C, then 70wt% Cr ₃ C ₂ -20wt% Cr- 9.7wt% Ni-0.3
Carbide composed of wt% C is sprayed to a thickness of 100 μm, and then
930 ℃ × 10h in chromium halide gas containing hydrogen gas
Heat treatment at 950 ℃ × 10h in vacuum
Post heat treatment is performed. (4) Film of (1) without post heat treatment in air (5) Film of (2) without post heat treatment in argon gas (6) Film of (3) in vacuum After the post-heat treatment was omitted, the following thermal spray coating was tested as a comparative example. (7) Fusing MSFCo1 150μm at 1050 ℃ (8) MSFCo1 150μm / 70wt% Cr ₃ C ₂ -20wt% Cr- 9.7wt
% Ni-0.3wt% C (9) MSFCo1 150μm / 88wt% WC-12wt% Co 100μm (10) 88 wt% WC-12wt% Co 150μm Immersion condition in molten zinc bath Composition of zinc bath Zn-0.3 wt % Al Temperature 480 ℃ Immersion time 7 days

Each of the above coatings was immersed in a molten zinc bath for 7 days and its appearance was observed. The results are shown in Table 2. As is clear from this result, the MSFCo1 single film (N
In o. 7), the coating was severely eroded by molten zinc and a large amount of zinc adhered. In addition, even if the upper layer of the MSFCo1 film is coated with Cr ₃ C ₂ -Ni ・ Cr (No. 8) and WC-Co (No. 9), no erosion of the film is observed,
Adhesion of zinc reached more than 80%. Furthermore, the same phenomenon was observed in the WC-Co film alone (No. 10). On the other hand, the coating conforming to the present invention has a Cr ₂₃ C ₆ type chromium carbide by heat treatment in a chromium halide gas containing hydrogen gas even if the carbide or carbide cermet film formed on the undercoat of MSFCo1 is provided. And the pores of the sprayed coating disappeared, and almost no metal component remained, so the adhesion of molten zinc was extremely low,
The film itself was also sound. However, the zinc adhesion area of the coatings (No. 1, 2, 3) that were post heat treated was only 2% or less, in comparison with the coatings that were not post heat treated (No. 4, 5, 6). In (), a little more zinc was admitted.
However, it is far less than the coatings of Comparative Examples (Nos. 8 and 9), and the heat treatment effect in a chromium halide gas containing hydrogen gas is well recognized. In the composite coating of the present invention, no significant difference was observed in zinc adhesion even when the MSFCo1 coating was fused or heat-sprayed and then directly heat-treated in a chromium halide gas containing hydrogen gas.

[0033]

[Table 2]

Example 3 The test piece of SUS 403 steel used in Example 2 was prepared according to the following (1)-
After forming the composite film conforming to the present invention and the films (5) to (9) of the comparative example, which were subjected to the treatment of (4), they were held at 610 ° C.
After being immersed in a 45 wt% Zn-55 wt% Al alloy bath for 5 days, it was pulled out from the bath and the state of molten metal adhesion and the state of film peeling were observed. 1. Composite coating of the present invention (1) MSFCo1 100 μm / 100 wt% WC 70 μm / Heat treatment in chromium halide gas containing hydrogen gas at 930 ° C. × 5 h / Post heat treatment at 900 ° C. × 1 h in argon (2) MSFCo2 100 μm / 50 wt% TiC − 25wt% Cr ₃ C ₂ −10wt
% HfC −10wt% ZrC −5wt% Co / Chromium halide gas containing hydrogen gas 850 ℃ × 20h Heat treatment / Vacuum 800 ℃
× 15h Post heat treatment (3) MSFWC1 100μm / 25wt% MoC -15wt% FeC -15wt%
CoC -10wt% SiC -10wt% NbC -10wt% TaC -14wt% Co
In chromium halide gas containing -1 wt% C / hydrogen gas
800 ° C. × 5h after heat treatment at 880 ° C. × 10h heat treatment / argon gas (4) 80wt% MSFCo1-10wt% Cr 3 C 2 -10wt% SiC / 70wt%
Cr ₃ C ₂ -10wt% WC-10wt% Ni-10wt% Cr / 800 ℃ × 15h heat treatment in chromium halide gas containing hydrogen gas / 900 ℃ × 5h post heat treatment in carburizing gas 2. Film of Comparative Example (5) MSFCo1 150μm at 1050 ° C. fusing (6) MSFCo1 150μm / 70wt% Cr 3 C 2 -20wt% Cr-9.7 wt
% Ni-0.3 wt% C (7) MSFWC1 150 μm fusing at 1070 ° C (8) 80 wt% MSFCo1-10 wt% Cr ₃ C ₂ -10 wt% SiC 150 μm
Fusing at 1070 ℃ (9) 88wt% WC-12wt% Co

Table 3 shows a summary of the above immersion test results.
It was done. As is clear from this result, the comparative example
MSF Co1 single film (No. 5), which was subjected to fusing treatment
Coating (No.7), Cr on the MSFCo1 layer₃C₂Shaped cermet
Formed film (No.6), Cr₃C ₂And SiC carbide cermet
The coating such as the one with a coated coating (No. 8) is for 5 days.
Molten metal adheres to almost the entire surface only by immersion, and WC-
No peeling of the coating was observed even with the Co cermet coating (No. 9)
However, molten metal adheres to 95% of the immersion
I was there. On the other hand, the composite film of the present invention (No. 1 to 4)
The best is that it adheres to 8% of the pickled area (No.1)
The molten metal film that adheres is thin and can be easily peeled off with your finger.
It was something that could be separated.

[0036]

[Table 3]

Example 4 The composite coating of the present invention used in Example 2 and the coating of the comparative example were dipped in a 90 wt% Al-10 wt% Si bath kept at 670 ° C. and pulled out of the bath every day. The appearance of the film was observed. Table 4 shows the results of immersion in the same bath as in the composite film example 2 of the same comparative example as the composite film example 2 of the present invention. As is clear from the results shown in Table 4, MSFCo1 (No. 5) of Comparative Example, a film (No. 6) formed with a carbide cermet on MSFCo1, and MSFCo1
WC The dispersed coating _{(No.7), r 3 C 2} , SiC and dispersed film (No.8) during MSFCo1, coating immersion of all one day is destroyed, the metal in the molten aluminum and the thermal spray coating The ingredients were tightly bound. In addition, the WC-Co film also had a remarkable adhesion of aluminum. On the other hand, the composite film according to the present invention has 3
It was durable enough to withstand immersion for a day, and the attached aluminum was weak enough to be easily peeled off with a finger. on the other hand,
The immersion temperature in this bath was very high, and since it was taken out of the bath twice a day and then put in water at 25 ° C for cooling, it was decided that a thermal shock test was carried out. .
In addition, as described above, in the film of the comparative example (No. 5 ~ 8),
Part of the film peeled off after one day of immersion, and one of the causes is considered to be thermal shock. In particular, a comparative example film in which a Cr ₃ C ₂ cermet was formed as the second layer (No. 6)
With the WC-Co coating (No. 9), when aluminum adhering to the surface was dissolved and removed with dilute hydrochloric acid, many cracks were found on the coating surface. On the other hand, the coatings of the present invention (Nos. 1 to 4) did not show cracks that could be visually discerned in the coating even after removing the aluminum adhering to the surface, and had a strong resistance to thermal shock. It turned out to have power.

[0038]

[Table 4]

[0039]

As described above, according to the present invention, a Co base alloy or a layer in which carbide is dispersed in the Co base alloy is formed as a first layer on a steel base material, and a second layer is formed as a second layer. A composite sprayed coating formed by forming a sprayed coating of a carbide or a carbide cermet and further heat-treating these coatings in a chromium halide gas containing hydrogen gas has at least a surface layer of Cr ₂₃ C ₆ type chromium carbide. Since it contains the main component, it does not undergo a metallurgical reaction even when it comes into contact with molten metal, and it exhibits extremely excellent resistance to molten metal with little adhesion of dross components.
Therefore, the member for hot-dip metal according to the present invention having such a modified thermal spray coating has a great effect on the quality improvement of the plated steel sheet, the stability of operation, and the cost reduction even in the actual hot-dip metal plating operation. Demonstrate.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an apparatus for heat treating a sprayed coating in a chromium halide gas containing hydrogen gas for producing a modified composite sprayed coating according to the present invention.

FIG. 2 is a schematic view of an apparatus in which an object to be processed is embedded in a penetrant and a heat treatment is performed while flowing hydrogen gas.

FIG. 3 is a sectional view showing a sectional structure of a modified composite thermal spray coating according to the present invention.

[Explanation of symbols]

1, 21 Treatment container 2 Chromium halide vapor introduction pipe 3 Argon gas introduction pipe 4, 22 Hydrogen gas introduction pipe 5, 23 Gas discharge pipe 6, 24 Temperature measuring pipe in treatment container 7, 25 Object 8 Shelf plate 26 Penetrant 31 Steel base material 32 Co-based alloy sprayed coating (first layer) 33 Carbide-based sprayed coating (second layer) 34 Cr ₂₃ C ₆ type chrome carbide layer 35 Carbide particles 36 Alloy layer 37 Alloy reaction layer

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-4-13857 (JP, A) JP-A-4-235269 (JP, A) JP-A-5-195253 (JP, A) JP-A-5- 295592 (JP, A) JP-A-8-74025 (JP, A) JP-A-8-74024 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C23C 4/10-4 / 18 C23C 10/10

Claims (7)

(57) [Claims] 1. A surface of a steel base material is provided with a Co-based alloy sprayed coating as a first layer, and a carbide-based sprayed coating is provided as a second layer on the first layer, and this second layer is provided. The carbide-based thermal spray coating of is a halogen-containing coating containing hydrogen gas.
Heat treatment for 1 to 20 hours at 600 to 1100 ℃ in chromium nitride gas
Between the deposited metal chromium and the carbon in the thermal spray coating.
If the Cr ₂₃ C ₆ type chromium carbide generated by the reaction is
Ku is have a modified layer formed by impregnating coated on said coating pores in in
And the modified layer is formed after the heat treatment.
In addition, in the atmosphere, in an inert gas, in a vacuum or in a carburizing atmosphere.
Post-heat treatment is performed at 600-1000 ℃ for 0.5-10 hours in ambient air.
And changed the residual metal chromium to Cr ₂₃ C ₆ type carbide
A member for molten metal resistant , comprising: 2. The Co-based alloy sprayed coating has a thickness of 30 to 500 μm.
The member according to claim 1, wherein the member is made of a Co-based alloy in which carbide particles are dispersed in addition to the Co-based alloy of m. 3. The carbide-based sprayed coating has a thickness of 30 to 300 μm.
m, MnC, FeC, NiC, CoC, SiC, WC, MoC, BC, CrC, N
It is characterized by comprising a carbide cermet composed of one or more carbides selected from bC, TaC, HfC, ZrC and TiC, or a mixture of these carbides and one or more metals selected from Co, Ni and Cr. The member according to claim 1. 4. A Co base alloy is first sprayed on the surface of a steel base material to form a Co base alloy spray coating, and then a carbide or carbide cermet spray coating is further formed on the spray coating. Next, these sprayed coatings were subjected to 600 to 1100 in a chromium halide vapor generation atmosphere containing hydrogen gas.
° C., then heated for 1 to 20 hours, precipitated by reaction with such free carbon of the activated metallic chromium particles and thermal spray coating in which occurs during the treatment atmosphere by the hydrogen reduction reaction at the time of heating Cr
₂₃ C ₆ type chromium carbide is formed on the surface of the carbide-based sprayed coating and in the pores to form a modified layer, and thereafter, the sprayed coating including the modified layer is exposed to the atmosphere or an inert gas. , 600 to 1100 in vacuum or carburizing atmosphere
° C., the residual heat treated after the condition of 1 to 20 hours metal black
A method for manufacturing a member for molten metal resistant, characterized in that the Cr content is also changed to Cr ₂₃ C ₆ . 5. The Co-based alloy sprayed coating has a thickness of 30 to 500 μm.
The manufacturing method according to claim 4 , which is composed of a Co-based alloy in which carbide particles are dispersed in addition to the Co-based alloy of m. 6. Co-based alloy sprayed coating, after spraying the Co-based alloy, a manufacturing method according to claim 4 or 5, characterized in that formed by further fusing treatment. 7. The surface of the steel base material is sprayed by MnC, Fe.
C, NiC, CoC, SiC, WC, MoC, BC, CrC, NbC, TaC, HfC,
Carbide cermet consisting of one or more carbides selected from ZrC and TiC, or a mixture of these carbides and one or more metals selected from Co, Ni, Cr is 30 to 300 μm
The method according to claim 4 or 5 , wherein thermal spraying is performed to a thickness of.