JP2982944B2 - Immersion member for hot-dip galvanizing bath - 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 used by dipping in a galvanizing bath, and more particularly to a sink for use in a zinc or zinc-aluminum alloy plating bath in a facility for manufacturing a galvanized steel sheet. Related to members such as rolls and support rolls. In other words, when spraying ceramics that are difficult to react with molten zinc and hard to wet on the surface of these members, a sprayed material that can prevent the erosion of the molten zinc alloy as a lower layer coating and enhance the bonding between ceramics and metal It is characterized in that the immersion member has a two-layered film formed by thermal spraying.

[0002]

2. Description of the Related Art As a method for producing a galvanized steel sheet,
The continuous hot-dip galvanizing method is mainly employed. The main steps of the continuous hot-dip galvanizing method are as follows. That is, the steel strip whose surface has been cleaned has an aluminum content of 0.1%.
After being immersed in a molten zinc alloy bath containing ~ 0.2%, the direction of movement is changed by a sink roll in the bath, and sent to a heating furnace via a support roll, a wiping nozzle, etc. to be subjected to alloying treatment. And cooled to room temperature.

In the above continuous hot-dip galvanizing process,
When the molten zinc erodes the immersion member, and when the steel strip passes through the aluminum-containing molten zinc, iron is eluted from the steel strip to the molten zinc, and a FeAl or FeZn-based solid phase metal is formed on the sink roll surface. Form a compound (called a deposited metal layer or dross). Since this adhered alloy layer is firmly and firmly adhered, the surface quality of the steel strip is deteriorated particularly in a high-grade plated steel sheet.

[0004] In order to prevent erosion of the immersion member by zinc and to prevent adhesion of a zinc alloy to the member, it has been proposed to spray a specific material onto the surface of a sink roll or a support roll. One of the roles of the surface spraying is to prevent the erosion of the member surface by the zinc alloy, and the other is to prevent the formation of the adhesion alloy layer (dross adhesion) on the surface of the member. For example, in Japanese Patent Application Laid-Open No. 4-116147, Cr ₃ C ₂ , WC, TiC, TiB ₂ , CrB ₂ , Z
A cermet sprayed material in which a non-oxide ceramic such as rB ₂ is mixed with Co, Cr or the like is disclosed in Japanese Patent Application Laid-Open No. 5-788.
No. 01 discloses Fe-containing Fe containing 22% or more of Al on the member surface.
A thermal spraying material for forming an Al alloy layer is disclosed in Japanese Patent Application Laid-Open No. HEI 5-106011, furthermore, Al ₂ O ₃ —TiO ₂ pseudo-2.
A thermal spray material of a base metal oxide has been proposed.

[0005]

However, oxide ceramics are excellent in molten zinc erosion resistance and zinc alloy adhesion resistance, for example, as in the thermal spraying material disclosed in Japanese Patent Laid-Open No. 5-106011, but have low mechanical strength. Therefore, when used by spraying on an actual roll, the sprayed coating often cracks or peels off, and is unsuitable as a protective coating.

[0006] Further, non-oxide ceramics have poor adhesion and mechanical strength similarly to oxide ceramics, and the addition of a metal component is indispensable for improving these. For example, the thermal spray material disclosed in Japanese Patent Application Laid-Open No. 4-116147 is a cermet material in which Co, Cr, etc. are mixed, but there is erosion of a zinc alloy.
There is dross adhesion on the surface.

In Japanese Patent Application Laid-Open No. 5-78801, Fe-
Al is almost the same component as dross, and adhesion of dross is remarkable.
Japanese Patent Application Laid-Open No. 5-33113 discloses a thermal spraying material in which 0.1 to 20% of Fe-Al is added to non-oxidizing ceramics. When Al is added, the diffusion rate of zinc decreases,
He emphasizes that the effect of adding Al is large, but points out that the effect brought about by adding Al to the oxide ceramic is poor because the oxide ceramic has poor matching with the metal.

[0008] The performance requirements of the above-mentioned sprayed coating for hot-dip galvanizing-related equipment include (1) hot-dip galvanized alloy erosion resistance,
(2) Dross adhesion resistance, (3) denseness and (4) mechanical strength.

Ceramics are materials having the above-mentioned characteristics (1) and (2), but ceramics have low toughness and a high porosity as compared with metal sprayed coatings. The diffusion at the interface is not easy, the bonding strength is small, and there is a risk of peeling of the coating during use as compared with the metal spray coating, so the above proposal has been made, but the performance requirements of the spray coating are sufficiently No satisfactory thermal spray material has been developed.

Accordingly, an object of the present invention is to provide a sprayed coating formed on the surface of a member, which coating is excellent in both the erosion resistance and the dross adhesion resistance of the molten zinc alloy, and which has high density and sufficient mechanical strength. An object of the present invention is to provide an immersion member for a galvanizing bath having stickiness resistance.

[0011]

Means for Solving the Problems As a result of researching to achieve the above object, the present inventor has taken advantage of the advantages of ceramic sprayed coatings, and the drawback is that two-layer coating is performed, that is, the metal member surface is coated. the (Fe _x Al _y intermetallic compound + oxide ceramics) sprayed cermet, yet can be removed if so spraying ceramic and same type of ceramic in the cermet to withstand molten zinc alloy erosive The present inventors have found that a dipping member having a sprayed coating having excellent adhesion resistance to zinc alloy and exfoliation resistance can be obtained, and arrived at the present invention. The appropriate thickness of the coating is 80 to 120 μm for the lower layer and 40 to 80 μm for the upper layer.

That is, the present invention firstly provides a member having a spray-coated film on a surface to be used by being immersed in a hot-dip galvanizing bath, wherein the member is composed of a Fe _x Al _y intermetallic compound and an oxide ceramic. A cermet layer formed by directly spraying a spraying powder material made of a mixture on the surface of a member, and a ceramic formed by spraying a spraying powder material made of the same type of ceramic as that contained in the cermet on the cermet layer Provided is a hot-dip galvanizing bath immersion member excellent in hot-dip galvanized alloy erosion resistance and zinc alloy-adhesive property, characterized in that a peel-resistant coating having a two-layer structure consisting of layers is formed on the member surface. by and; to a 2, Fe _x Al _y intermetallic compound x = 1 to 3 of the cermet layer, y =. 1 to
The present invention is to provide the above-mentioned member, which is an intermetallic compound corresponding to 5 and wherein the added amount of the mixed oxide ceramic is 5 to 70% by weight based on the total amount of the intermetallic compound and the oxide ceramic. (However, the Fe _x Al _y
In the above, the bond between Fe and Al must be an intermetallic compound. A simple alloy bond between Fe and Al has low resistance to Zn erosion and is unsuitable as a protective coating. The composition of the FeAl intermetallic compound is Fe ₃ Al, FeAl ₂ , Fe ₃ A
_{l 5, FeAl 8 (x =} 1~3, y = 1~5) but the like, most of anti-Zn erodible is strong FeAl _2, Fe ₃
Al ₅ . Third, the oxide ceramic is made of Al ₂ O ₃ , stabilized or partially stabilized ZrO ₂ ,
Cr ₂ O ₃ , ZrSiO ₄ and spinel (Al ₂ O ₃
(MgO) is at least one member selected from the group consisting of:
Another object is to provide a member according to the second aspect.

[0013]

The coating formed by spraying the immersion member of the present invention has improved bonding between ceramics and metal,
Sprayed (FeAl ₂ + oxide ceramics) as the lower layer of the coating has excellent resistance to zinc erosion, so that even if zinc is infiltrated, the base layer is not eroded even if zinc penetrates, and the protective effect is low. There is a characteristic that it can be adjusted so that a film having an expansion coefficient equivalent to that of the material to be sprayed is formed. The reason why the amount of ceramics added to the lower layer cermet is set to 5 to 70% is that if it is less than 5%, the volume ratio of the ceramics is too small, and if it exceeds 70%, the volume ratio of the ceramics is too large. Since the effect is poor, the content is set to 5 to 70%.

[0014]

Embodiment 1 FIG. 1 is a schematic sectional view of an experimental apparatus commonly used in an embodiment of the present invention and a comparative example. This will be described below with reference to this figure.

A crucible 4 mounted on a table 6 provided at the bottom of a furnace body 8 whose inside is maintained at a predetermined temperature by a heater 1
Zinc-0.1% aluminum alloy 5 stored inside
In the inside, a rod-shaped sample (SUS40
3 and a diameter of 20 mm and a length of 275 mm) are rotated in a soft iron cylinder 3 having a window 7.
1 to 0.15 mm cermet layer (FeAl ₂ 80 wt%
+ Al ₂ O ₃ 20wt%) film was sprayed, Al ₂ thereon
A sprayed sample 2 having a ceramic layer of O ₃ sprayed was prepared and set in a furnace. Then, the inside of the furnace was adjusted to a hydrogen-nitrogen atmosphere of 460 to 550 ° C., and an immersion experiment was performed.

As a result of immersion for two weeks or more, it was confirmed that the sprayed coating of the rod-shaped sample tested did not easily react with the molten zinc and had extremely high stability.

[0017]

Example 2 Using the experimental apparatus shown in FIG. 1, a rod-shaped sample was used as a cermet layer (80 wt% of FeAl ₂ +20 wt% of ZrO ₂₎ .
%) An immersion experiment was performed in the same manner as in Example 1 except that the coating was sprayed and a ZrO ₂ ceramic layer was sprayed thereon. As a result, no abnormality was found after 2 weeks.

[0018]

COMPARATIVE EXAMPLE 1 Using a test apparatus shown in FIG. 1, a sprayed sample obtained by spraying a WC-Co cermet layer on a rod-shaped sample was subjected to an immersion test according to the procedure of Example 1. As a result, dross adhered to the entire surface of the sprayed sample.

[0019]

Comparative Example 2 Using the experimental apparatus shown in FIG. 1, a bar-shaped sample was sprayed with a cermet layer of a cobalt-based alloy and Al ₂ O ₃ , and a ceramic layer of ZrO ₂ was further sprayed thereon. An immersion experiment was performed according to the procedure of Example 1. Examination of the coating on the thermal sprayed sample that was tested revealed that the erosion by zinc in the bath extended to the SUS base metal.

The experimental results obtained in the above Examples and Comparative Examples are summarized in Table 1.

[0021]

[Table 1]

[0022]

Example 3 A cermet layer (80 wt% FeAl ₂ ) similar to that of Example 1 was applied to a support roll drive shaft (spindle) used in a bath of a galvanizing bath for an automobile outer panel in which the bath temperature was maintained at 450 to 480 ° C. + Al ₂ O ₃ 20 wt%) and a ceramic coating (Al ₂ O ₃ ) having a two-layer structure was formed by thermal spraying. The following effects were confirmed as a result of applying galvanization to an automobile outer panel using this member. (1) Rotational shake of the support roll due to dross winding can be effectively prevented. (2) The work of removing dross wrapped around the spindle becomes unnecessary. (3) Conventionally, when SUS403 material is used, if dross adheres, it cannot be reused and has a short life as a base material.
The formation of a two-layer spray coating according to the method of the present invention allows the spray coating to be reclaimed and reused, extending the life of the alloy.

[0023]

Embodiment 4 A cermet layer (80 wt% of FeAl ₂ +
(ZrO ₂ 20 wt%) The same operation as in Example 3 was carried out except that ZrO ₂ was formed as a ceramic layer thereon, and it was confirmed that the same effect as in Example 3 was obtained.

[0024]

As described above, in the immersion member provided with a thermal spray coating according to the present invention, the thermal spray coating is a two-layer coating of a lower layer of a cermet layer and an upper layer of a ceramic layer of the same type as the ceramic contained in the cermet layer. Even if the ceramic layer has low density and the zinc penetrates, the base material will not be attacked even if zinc penetrates, and it has peeling resistance along with molten zinc erosion resistance and zinc alloy adhesion resistance, and excellent protection for members Has an effect.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an immersion test apparatus commonly used in Examples and Comparative Examples of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heater 2 Thermal spray sample 3 Soft iron cylinder 4 Crucible 5 Molten zinc-aluminum alloy 6 units 7 Window 8 Furnace 9 Rotation axis

──────────────────────────────────────────────────続 き Continuing on the front page (72) Michihiko Tsuchiya 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Kawasaki Steel Corporation Chiba Works (72) Inventor Hiroaki Kishida 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Kawasaki Steel In Chiba Works, Ltd. (72) Inventor Harumasa Muramoto 1 Kawasaki-cho, Chuo-ku, Chiba City, Chiba Prefecture Kawasaki Steel Works Chiba Works, Ltd. (56) References JP-A-4-350154 (JP, A) (58) Survey Field (Int.Cl. ⁶ , DB name) C23C 4/10

Claims (3)

(57) [Claims] 1. A member of the thermal spray coating is applied to the surface to be used was immersed in molten zinc plating bath, _Fe x Al
_y A cermet layer formed by directly spraying a thermal spraying powder material comprising a mixture of an intermetallic compound and an oxide ceramic on the surface of a member, and further an oxide ceramic of the same type as that contained in the cermet layer And a ceramic layer formed by thermal spraying of a powder material for thermal spraying comprising: Excellent immersion member for hot dip galvanizing bath. 2. The method according to claim 1, wherein the Fe _x Al _y intermetallic compound of the cermet layer is an intermetallic compound corresponding to x = 1 to 3 and y = 1 to 5; The member according to claim 1, wherein the amount is 5 to 70% by weight based on the total amount of the oxide ceramic and the oxide ceramic. 3. The method according to claim _2, wherein the oxide ceramic is Al ₂ O ₃ ,
Stabilized or partially stabilized ZrO ₂ , Cr ₂ O ₃ ,
The member according to claim 1, wherein the member is at least one selected from ZrSiO ₄ and spinel (Al ₂ O ₃ .MgO).