JP3160387B2 - Composite thermal spray material and composite thermal spray coating excellent in molten metal resistance - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a powdery or granular composite sprayed material having excellent resistance to molten metal and a composite sprayed coating formed by spraying the material.

[0002]

2. Description of the Related Art Plating layers such as hot-dip galvanizing, hot-dip aluminum plating, hot-dip zinc-aluminum alloy plating exhibit excellent rust and corrosion resistance. It is a useful surface treatment technology that has been used for a long time in main components such as home appliances and still plays a major role even today.

[0003] In particular, plating of hot-dip galvanized steel sheets, which are produced in large quantities, is often performed by continuous plating as shown in FIG. This continuous hot-dip galvanizing apparatus includes a sink roll 2 immersed in a plating bath 1, a support roll 3 disposed near the surface in the plating bath, and a plated steel sheet 4 after passing through these rolls. A guide roll 5 for guiding, an injection nozzle 6 for blowing off excess zinc attached to the steel plate with nitrogen gas or water vapor, and the like are provided. Here, the plating member to be sprayed with the composite sprayed material according to the present invention is immersed in a plating bath, or molten zinc is scattered and adhered,
Alternatively, the zinc plated on the steel sheet is placed at the place where it comes into contact with the softened condition, and (1) the erosion by molten zinc is unlikely to occur, (2) even if it comes in contact with the threading material (steel sheet) (3) Easy removal of adhered molten zinc and easy maintenance and inspection, (4) Long life as a plating member and low cost, (5) Immersion in hot zinc bath It is required to well withstand the thermal shock when it is performed.

[0004] In order to meet such a demand, taking a film for a sink roll as an example, (1) An alloy based on a Co-based self-fluxing alloy specified in JIS H8303 (1976) described in Japanese Patent Publication No. 58-11507. A film with a composition formed. (2) JP-A-61-117260
As disclosed in Japanese Unexamined Patent Publication (Kokai) Publication No. H8-78, a ceramic coating composed of ZrO ₂ and Al ₂ O ₃ is spray-formed, (3) As disclosed in Japanese Patent Publication No. 58-37386, WC, Cr ₃ C ₂ , TiC For one or two or more types, a hot corrosion resistant metal such as Ni or Si, or a 0.1 to 2.4 mm thick film formed by coexisting these oxides, mainly formed by a thermal spraying method, has been proposed. With respect to the above-mentioned technologies, the inventors have also conducted research on the development of similar technologies. (4) In Japanese Patent Application No. 63-49846 (Japanese Patent Application Laid-Open No.
Thermal spray coating having a porosity of 1.8% or less and a film thickness of 0.040 to less than 0.10 mm.
No. 192753 (Japanese Unexamined Patent Publication No. 2-43352), a method in which a boride or a material containing 5 to 28% of Co is formed by a low pressure plasma spraying method. No. 2-236266), using a material in which ZrB ₂ , TiB ₂ and various carbides contain 5 to 40% of Ta and Nb were used, and the coating surface roughness was reduced to Ra 0.01 to
5 μm, having a film with a porosity of 1.8% or less,
(7) In Japanese Utility Model Application No. 1-124010 (Japanese Utility Model Application Laid-Open No. 3-63565), a film in which Cr ₃ O ₃ is formed by a chemical densification method on a cermet sprayed coating mainly composed of carbide; Japanese Unexamined Patent Application No. Hei 2-201187 (Japanese Patent Application Laid-Open No. 4-88159) discloses a coating obtained by converting a part of a carbide sprayed coating into a boride by boride treatment. .1) by heating and diffusing Al or Al-Zn alloy to various carbides, borides or their cermet sprayed coatings,
Various technologies and films have been proposed, such as improving the resistance to molten zinc.

[0005]

As can be seen from the above examples, the research issues regarding the thermal spray coating formed on the conventional hot-dip galvanized member are to select a hot-dip galvanizing coating material and to improve the adhesion of the coating. In addition, improvement of the surface roughness and denseness of the film is mainly occupied, and the improvement effect is recognized respectively. However, with the recent increase in the demand for hot-dip galvanized steel sheets, the demand for improving the operation rate of the plating plant and the quality of the coated steel sheets has become extremely strong. Adhesion of the fine dross component (Zn-Fe, Zn-Fe-Al alloy) to the sprayed coating surface It has become. Therefore, an object of the present invention is to provide a composite sprayed material which can sufficiently satisfy these requirements and has excellent resistance to molten metal, and a composite sprayed coating formed by spraying using this material.

[0006]

As a result of various experiments and studies, the present inventors have found that the penetration of molten zinc into a sprayed coating can be prevented by employing a dense carbide or carbide cermet coating. On the other hand, it has been found that it is effective to prevent the adhesion of the dross component by using a boride that does not react with the molten zinc by metallurgy. For this reason, in the composite thermal spraying material of the present invention, which is excellent in molten metal resistance, the particles of the mixed thermal spraying material composed of carbide or carbide cermet particles and boride are preliminarily composite-integrated, whereby the thermal spraying is performed. During the operation, the two components were sprayed and formed into a film in a composite state without separation. That is, the present invention is characterized in that, in a composite thermal spray material obtained by mixing each particle of carbide or carbide cermet and boride, each of the above-mentioned particles of carbide or carbide cermet and boride are preliminarily compositely integrated. We propose a composite sprayed material that is excellent in molten metal resistance. Further, the present invention provides a composite spray formed by spraying a sprayed material of a carbide which is preliminarily melt-bonded with a boride or provided with a boride coating layer on the surface or a carbide cermet sprayed material which is subjected to the same treatment. Suggest a coating. The composite thermal spray coating formed by thermal spraying the composite thermal spray material is a film having both the property of preventing intrusion of molten zinc, which is a property of carbide and carbide cermet, and the property of preventing dross component adhesion of boride. .

[0007]

The main components constituting the thermal sprayed material of the present invention are carbides, borides and metals constituting cermets. Such carbides include TiC, NbC, WC, Cr ₃ C ₂ , B ₄ C, TaC,
BiC, ZrC, etc. are advantageously adapted HfC or VC, as such _{boride, TiB 2, ZrB 2, HfB} 2, VB 2, TaB 2, NbB 2,
W ₂ B ₅ or CrB ₂ or the like is advantageously suitable, and as a metal component constituting the above-mentioned carbide cermet, Co,
Any one or more of Ni, Cr, Al, and Fe are used.

Each of these main components has the following characteristics. Carbide exhibits strong erosion resistance to molten metal, that is, the property of preventing molten zinc from entering the inside, but is not easily melted by itself. However, when a metal coexists, this acts as a binder to facilitate the formation of a thermal spray coating. Borides are characterized by having a higher erosion resistance to molten metal than carbides, and have a substantially large contact angle with molten metal, are hardly wet, and do not react with the molten metal. The present invention intends to utilize this property for the purpose of preventing the dross component floating in the molten zinc bath from adhering. Further, the boride exhibits a stable molten state, so that thermal spray deposition is easy. The metal component essentially reacts with the molten zinc to form an alloy, while it can also react with carbides and borides to form intermetallic compounds. This intermetallic compound is characterized by facilitating the formation of a thermal spray coating and improving the resistance to molten zinc as compared with a single metal.

[0009] Some of the commercially available carbides may contain free carbon depending on the production conditions, and the metal material may contain C, Si, Mn, P, S and other impurities. It should be noted that the amount of the components to be mixed is not particularly specified because no phenomena that hinder the object of the present invention are observed.

An example of manufacturing the thermal spray material of the present invention using the above materials will be described. (1) A boride powder is mixed with a commercially available carbide cermet powder, and at least a part of both components is melted by a mechanical alloying method or a mechanofusing method so as to be integrated. At this time, the binding of both powders can be promoted by adding a polymer binder (mechanical composite method). (2) by exposing a commercial carbide cermet powder to boride vapors, in particular halogen boride vapors,
Boron or boride is deposited on the surface of the carbide cermet powder and coated by vapor deposition (CVD method). (3) Boron or boride in a vacuum vessel is irradiated with an electron beam to vaporize it, and a carbide cermet powder is exposed to the vapor to deposit and coat boride on the surface (PVD). Law). (4) Commercially available carbide cermet is melted borax (Na ₂ B ₂ O ₇ )
The surface of the carbide cermet powder is boridified by immersion and impregnation therein. Instead of this borax, NH
_A method in which a carbide cermet powder is added to a ₄ Cl + B ₄ C mixed powder and heated at 600 ° C. to 800 ° C. for 1 to 3 hours to impregnate a boride may be used (thermal diffusion method).

[0011] The thermal spray powder material produced in this way is:
Materials with significantly different specific gravities such as WC (about 15.6), TiB ₂
(Approximately 4.4) can be handled as one powder particle (composite particle). Therefore, once the composite is integrated, these two components do not separate during the thermal spraying operation. The particles integrated into a composite are pulverized and adjusted to a particle size suitable for thermal spraying, if necessary. That is, for thermal spraying, diameter 5
If it is less than 50 μm, fumes are formed during thermal spraying, and if it is more than 50 μm, undesired particles are mixed and formed when forming a coating film, which is not preferable because voids are generated and the interparticle bonding force is reduced.

Next, a method of forming a thermal sprayed film using the above-described composite thermal spray material will be specifically described. As described above, since the sprayed material of the present invention is all in a powder state, the film is formed by a plasma spraying method, a flame spraying method using a combustible gas combustion flame as a heat source, or an explosive spraying method. It is preferable to form a film by a method. Also,
In forming such a thermal spray coating, carbides, borides, cermets or composite particles thereof can be arbitrarily selected according to the purpose of use, so that those thermal spray materials can be formed into a layered structure or formed into a gradient structure. It is possible. For example, (1) a carbide cermet is formed to a thickness of 50 μm by flame spraying, and composite material particles are further
(2) Varying the mixing ratio between the carbide cermet material and the composite powder material, increasing the carbide cermet content toward the steel base material and increasing the composite material ratio toward the upper layer. It is possible to freely select the proportion of the constituent components of the film formation, such as formation of a film having a high structure.

By the way, it is important that the thermal sprayed coating formed in this way is made dense, and in the case of a porous coating, the molten zinc penetrates through the pores and enters the inside, so that it has no problem. Even if a film is formed using a molten material having excellent molten zinc properties, its function cannot be sufficiently exhibited.
For this reason, at the time of thermal spray deposition, a plurality of thermal sprays are repeated to obtain a predetermined film thickness so as to obtain a film thickness of 3 to 30 μm per pass by adjusting the supply amount of the thermal spray powder to the thermal spray gun. It is preferable that When the film thickness per pass is thinner than described above, a denser film can be obtained, but it takes a long time to obtain a practical film thickness of, for example, 100 μm, which is not economical. On the other hand, when the film thickness per pass exceeds 30 μm, the porosity of the film becomes high, and the bonding force between the particles constituting the film becomes weak, so that there is a disadvantage that the film is easily peeled.

The most significant feature of the thermal sprayed material of the present invention produced by the above-described method and the thermal sprayed coating formed by using this material is that carbide or carbide cermet particles and boride having excellent molten metal resistance are used. The point is that they are completely integrated into a single particle. For this reason, the surface of the coating formed by the thermal spray material of the present invention exhibits a state in which the composite particles composed of carbide, boride, metal, etc. are uniformly distributed, and the probability that boride is always present on the surface of the particles. Is high. On the other hand, if thermal spraying is performed with carbides, borides, metals, etc. simply kept in a mixed state, or simply with carbide cermets and borides mixed, high-speed particles will be formed and fly. The specific gravity of each material (for example, WC specific gravity about 15, TiB ₂ specific gravity about 4.4, Ti
Separation phenomena occur due to a difference in specific gravity of C of about 4.9, a specific gravity of CrB ₂ of about 5.2), a difference in particle size, and the like. For this reason, no matter how even the sprayed material is mixed, the distribution of the powder material components becomes extremely uneven on the surface on which the sprayed film is formed, and as a result, the penetration rate of the molten metal into the inside becomes high, There is a defect that makes it easy for components to adhere. That is, the adhesion of the dross component often grows with the metal part existing on the surface of the sprayed coating as a nucleus.
Dross adhesion cannot be prevented. In this regard, in the composite sprayed material of the present invention, as shown in the above-mentioned powder processing example, since the boride is always in a state of being coated with the metal, a portion serving as a nucleus of the adhesion of the dross component is formed on the film surface. Is almost nonexistent.

[0015]

【Example】

(Example 1) The following experiment was conducted in order to investigate the molten zinc resistance of a thermal spray coating formed by thermal spraying the material according to the present invention. First, structural carbon steel (SS400) diameter 15 x length 200m
m was used as a base material, and a film having a thickness of 100 μm was formed on the surface thereof using the powder materials (1) to (13) below by a high-speed gas flame spraying method and a plasma spraying method. The materials (1) to (9) were manufactured by a mechanical composite method, and the other materials (10) and (11) were manufactured by a mechanical mixing method.
The materials (3) and (14) were produced by the melt-pulverization method, and the material (12) was produced by the spray method.

[0016] (1) (85WC-11Co) -4TiB 2 (2) (80TiC -1Ni -2Cr -10Al) -7TiB 2 (3) 80Cr 3 C 2 -20ZrB 2 (4) (84WC-10Co-2Al) - 4CrB ₂ (5) (90TiC −5Al −2Fe) −3TiB ₂ (6) (88WC−12Co) 50μm (1) 50μm (7) (83WC−17Co) 70μm (2) 30μm ( 8) (88WC-12Co) 80μm (3) 20μm (9) (83WC-17Co) 50μm (4) 50μm (10) (88WC-12Co) (11) (83WC-17Co) ( 12) self-fluxing alloy (JIS H8303, MSFCo1) (13 ) 100Al 2 O 3 (14) 8Y 2 O 3 of -92ZrO ₂ or more materials (10) to (14) are those prepared for comparison, The numbers in parentheses indicate powder particles of one cermet.

Next, the material having a sprayed coating obtained by spraying the composite sprayed material was immersed in a molten zinc bath. The conditions are as follows. (1) Zinc bath composition 0.05 as dross component in pure zinc
(2) Temperature 480 ° C (3) Immersion time 10 days Observation of the appearance of the film after immersion, cutting of the test piece film, and cross-section of the film with an optical microscope and an X-ray microanalyzer. The state of penetration of zinc into the coating was observed.

Table 1 summarizes the results.
A large amount of zinc adhered to the surface of the self-fluxing alloy of the No. 12 comparative material, and the self-fluxing alloy film was eroded by zinc, exposing the base metal locally. No.13 100A
Both l ₂ O ₃ film and 8Y ₂ O ₃ · 92ZrO ₂ film of No.14 is peeled off more than 50% of the coating, even the base material has been甚properly eroded by zinc here. However, No.10 and No.11
In the WC-Co film, although the zinc was eroded, the film itself was not destroyed. However, adhesion of dross components was observed on the film surface. On the other hand, in the film made of the material of the present invention, the penetration depth of zinc into the inside thereof is 3 to 10%.
In addition to being in the μm range, no dross component was found to adhere and the condition was extremely clean and healthy.

[0019]

[Table 1]

(Example 2) In this example, while being identical in chemical composition to the composite thermal spray material of the present invention, particles of carbide (including carbide cermet), boride, metal and the like are simply mixed. We investigated the molten zinc resistance and the adhesion of dross components of the 100-μm-thick film formed by plasma spraying.

[0021] - composite spray material (all components are integrated) of the present invention (1) (85WC -11Co) -4TiB 2 (2) (80TiC-1Ni -2Cr -10Al) -7TiB 2 (3) 80Cr 3 the _{C 2 -20ZrB 2 (4) (} 84WC -10Co-2Al) -4CrB 2 (5) (90TiC-5Al -2Fe) -3TiB 2 · spray material for comparison (6) (85WC-11Co) in 4TiB ₂ mechanically mixing (7) (80TiC-1Ni -2Cr -10Al) mechanically mixing mechanically mixed (8) 80Cr ₃ C ₂ and 20ZrB ₂ the _{7TiB 2 (9) (84WC -10Co} -2Al) 4CrB ₂ is mechanically mixed (10) (90TiC-5Al-2Fe) is mechanically mixed with 3TiB ₂ Here, the zinc bath composition for spray coating immersion, temperature, immersion time, and procedures for investigating the coating after immersion, etc. Was the same as in Example 1.

The results of the survey are summarized in Table 2. As is evident from these results, the penetration depth of zinc from the surface of the No. 6 to No. 10 coatings formed with the comparative sprayed material was within 30 μm, and in this respect, the zinc Sex is recognized. However, dross components adhered and grew on the surface of the film. Microscopic observation of the surface of the film to which the dross component adhered revealed that a metal component was present at that portion, and dross was adhered to the metal component. On the other hand, in the No. 1 to No. 5 coatings formed of the composite thermal spray material of the present invention, the penetration depth of zinc was 5
It was not more than μm, and there was no dross component attached, showing an extremely healthy and clean state. When the surface of the film was examined with a magnifying glass and EPMA, it was in a state where boride was covered almost entirely, and it is considered that there was no adhesion phenomenon of the dross component.

[0023]

[Table 2]

(Embodiment 3) In this embodiment, aluminum
The applicability of the plasma sprayed coating using the composite sprayed material of the present invention to a (55) -zinc (45) alloy bath was experimentally investigated. Also here, the thickness of the thermal spray coating was 100 μm, and the same comparative material as in Example 2 was used.

[0025] - composite thermal spray material of the present invention (1) (85WC -11Co) -4TiB 4 (2) (80TiC-1Ni -2Cr -10Al) -7TiB 4 (3) 80Cr 3 C 2 -20ZrB 2 (4) ( 84WC −10Co−2Al) −4CrB ₂ (5) (90TiC−5Al −2Fe) −3TiB ₂・ Spray material for comparison (6) 4TiB ₄ is mechanically mixed with (85WC-11Co) (7) (80TiC -1Ni -2Cr -10Al) mechanically mixing 7TiB ₂ to (8) 80Cr ₃ C ₂ and 20ZrB ₂ mechanically mixed (9) (84WC -10Co-2Al ) mechanically mixing 4CrB ₂ (10 ) (90TiC-5Al -2Fe) mechanically mixing and aluminum 3TiB ₂ - immersion conditions to zinc alloy bath (1) bath composition aluminum 55 wt% - Fe zinc 45 weight%
(2) Temperature 605 ° C (3) Immersion time 10 days The film after immersion was evaluated in the same manner as in Examples 1 and 2.

Table 3 summarizes these results. As is clear from the results, the coatings of No. 6 to No. 10 formed with the comparative thermal spray material did not show any destruction in appearance, but a large amount of dross component adhered and the cross section was Inspection revealed that some of the zinc was completely coated (10
0 μm thick) and reached the base metal. On the other hand, in the thermal spray coating formed using the composite thermal spray material of the present invention, penetration of zinc is limited to a depth of 30 to 60 μm, and adhesion of dross component is slight. The film of No. 5 was hardly recognized and showed a good appearance.

[0027]

[Table 3]

Example 4 In this example, the resistance of the coating formed from the thermal sprayed material of the present invention to melting was evaluated.
In order to investigate the molten aluminum properties,
Structural carbon steel of dimensions is used as a base material, and the following (1)
~ (High-speed coating of 150μm thick using powder material of 12
It was formed by gas flame spraying and plasma spraying. In addition,
Materials (1) to (7) are manufactured by the mechanical composite method
(8) and (9) are mechanical mixing, (10) is spraying, (1)
1) and (12) are commercial products manufactured by the melt pulverization method.
You. (1) (84NbC-5Al-4Fe) -5NbB₂−2TiB₂  (2) (90B₄C-3Al-3Fe-1Co) -3TiB₂  (3) (84TaC-8Al-3Fe-2Co) -3VB₂  (4) (85SiC-7Al-1Fe-2Co) -5HfB₂  (5) (87ZrC-7Cr-2Al)-4W ₂ B ₅  (6) (80Cr₃C₂−10VC−5Ni −2Co) −3NbB₂  (7) (80WC −5TiC−10Co) −5TiB₂  (8) (80WC −12Co) (9) (83WC −17Co) (10) Self-fluxing alloy (JIS H8303, MSFCo1) (11) 100Al₂O₃  (12) 8Y₂O₃−92ZrO₂  Of the above materials, (8) to (12) were prepared for comparison
In the parentheses, one piece of cermet material is used.
Show particles. Next, these thermal spray coatings were
The condition was as follows. (1) Aluminum bath composition 0.1% iron powder added as a dross component to a pure aluminum bath. (2) Temperature 720 ° C (3) Immersion time 4 days.
Using an optical microscope and an X-ray microanalyzer.
Then, the state of penetration of aluminum into the inside of the film was observed.

Table 4 summarizes the results.
The self-fluxing alloy film of No. 10 was eroded by the molten aluminum, and the erosion of the base metal was remarkable. No.11 100 Al ₂ O
₃ coatings and 8Y ₂ O ₃ -92ZrO ₂ film of No.12, the base material is selectively eroded by aluminum together entering from the pores of the thermal spray coating, the coating was destroyed with peeling accordingly. Also, in the WC-Co cermet films of Nos. 8 and 9, the penetration of the molten zinc was severe, and the tip reached the vicinity of the base metal and dross components were attached. In addition, a chipping phenomenon was observed in a part of the film. In contrast,
In the film formed of the material of the present invention, the penetration depth of aluminum into the film remains within the range of 10 to 20 μm, and there is no adhesion of dross component, or the adhesion of dross is slight. Removal was very easy.

[0030]

[Table 4]

[0031]

As is apparent from the above examples, the thermal spray coating formed by using the composite thermal spray material according to the present invention, which is obtained by integrally integrating carbide or carbide cermet particles and boride, is formed of molten zinc. In addition, it has been found that not only the excellent molten metal resistance can be exhibited in the molten zinc-aluminum alloy bath and the aluminum bath, but also the adhesion of dross components floating in the bath can be prevented. As a result, a long-term continuous production of hot-dip coated steel sheets becomes possible, and it is possible to reduce the maintenance and inspection costs of equipment and production costs, and to expect a great effect on stable production of high-quality coated steel sheets without dross adhesion. Further, the sink roll having a sprayed coating formed by the composite material of the present invention is prevented from being eroded by the molten zinc, so that the roll material does not decrease in purity of the zinc bath due to elution into the zinc bath. Production of high-quality plated steel sheets can be expected from the aspect as well.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a hot-dip galvanizing bath, various rolls attached thereto, and other arrangement states.

[Explanation of symbols]

 Reference Signs List 1 molten zinc bath 2 sink roll 3 support roll 4 steel plate for plating 5 guide roll 6 injection nozzle

Claims (6)

(57) [Claims] 1. A composite spray material comprising a mixture of carbide or carbide cermet particles and boride,
A composite sprayed material having excellent resistance to molten metal, wherein each of the above-mentioned carbides or carbide cermet particles and a boride are compositely integrated in advance. 2. The composite integration of carbide particles or carbide cermet particles with boride is carried out by mechanical bonding, fusion bonding of each particle and boride, or by vapor coating or impregnation of boride on the particle surface. The composite thermal spray material according to claim 1, which is obtained. 3. The method according to claim 1, wherein the carbide is TiC, NbC, WC, Cr ₃ C ₂ , B
_2. The composite thermal spray material according to claim 1, comprising at least one of ₄ C, TaC, SiC, ZrC, HfC and VC. 4. The method according to claim 1, wherein the boride is TiB ₂ , ZrB ₂ , HfB ₂ , VB ₂ ,
_2. The composite thermal spray material according to claim 1, comprising at least one of TaB ₂ , NbB ₂ , W ₂ B ₅ and CrB ₂ . 5. The composite thermal spray material according to claim 1, wherein the metal component constituting the carbide cermet is one or more of Co, Ni, Cr, Al, and Fe. 6. A sprayed material of a carbide which has been previously melt-bonded with a boride or has a boride coating layer formed on its surface and which has been combined and integrated, or a carbide cermet which has been subjected to the same treatment. Composite spray coating.