JPH06322499A - Molten zinc erosion resistant alloy and its production and application - Google Patents

Abstract

PURPOSE:To provide the member which prevents erosion from molten zinc, obviates the precipitation of intermetallic compds., etc., of Al added into a bath, Fe eluted from a base material and zinc which is the essential component of the bath on a dense alloy film, has excellent corrosion resistance and wear resistance and is immersed into or brought into contact with the molten zinc by forming the alloy film described above on the surface of the base material without using a metallic binder such as Co. CONSTITUTION:This member has a coating layer consisting of an Mo-B alloy contg. 3 to 9wt.%, more preferably 6 to 8wt.% boron and forms the alloy in which at least a part of the boron exists in the form of MoB or Mo2B and the intermetallic compds. of MoB or Mo2B are precipitated in the molybdenum substrate. The precipitation phase of these intermetallic compds. have high hardness and wear resistance. The alloy is adequate for applications where the corrosion resistance and the wear resistance are simultaneously demanded and moreover, the alloy has the higher toughness than the toughness of 100% ceramics such as MoB.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a Mo-B alloy having excellent wear resistance and hot-dip zinc erosion resistance, a method for producing the same, and its use. In particular, it is immersed in a zinc bath such as a hot-dip galvanizing facility. Or a member having excellent corrosion resistance for use in contact with molten zinc and a method for manufacturing the same.

[0002]

2. Description of the Related Art Molten zinc is highly corrosive to metals and has a low surface tension and a low viscosity, so that it also penetrates into minute gaps of a micrometer unit.

Therefore, for example, a stainless steel material such as SCH-13 is generally used as a material for a pot roll of a steel plate plating line, but aluminum which is significantly corroded by zinc and is usually added to a zinc bath. Further, since iron leached from the steel plate or the roll base material and the ternary intermetallic compound with zinc which is the main component of the bath are deposited, the surface of the roll body is roughened in a short period of time.
This surface roughness causes a flaw in the steel sheet and deteriorates the quality of the steel sheet.

Therefore, conventionally, the following techniques have been proposed in an attempt to improve the member itself or form a coating on the member to prevent corrosion of the metallic structural member by molten zinc or precipitation of a zinc alloy on the member. Has been done. (1) Improvement of roll base material (2) Self-fluxing alloy spraying (3) Cermet spraying and build-up

[0005]

As an example of the above (1), there is an iron-based alloy member disclosed in, for example, Japanese Patent Laid-Open No. 56-112447, but since it is a metal alloy, it is used as a molten zinc bath dipping member. For practical purposes, sufficient corrosion resistance is not obtained.

Regarding the above (2), for example, Japanese Patent Laid-Open No. 1-
Like the member disclosed in 108335, Co, N
There is one in which an i or Fe-based self-fluxing alloy is sprayed on a base material and then a densified corrosion-resistant coating is formed by welding heat treatment. In many cases of actual use, some improvement effect is recognized, but the member is Since it is basically a metal alloy, the corrosion resistance for the above-mentioned practical purpose is still insufficient.

Further, the above (3) is a thermal spray coating of an alloy of a metal and a carbide or boride, or a mixed composition thereof, and, for example, like the member disclosed in Japanese Patent Laid-Open No. 1-225761, WC-Co. A member provided with a thermal spray coating layer of a cermet series, a member having a thermal spray coating layer of a cermet composed of a metal and a metal boride or a metal carbide, such as the member disclosed in JP-A-2-236266, or JP There is known a member such as the member disclosed in -94048 in which a carbide or boride-containing Co alloy is built up. However, in both cases, metal components such as Co added to obtain sufficient denseness are preferentially eroded by zinc, so that it is not possible to sufficiently exhibit the excellent corrosion resistance inherent to carbides and borides. . Conventionally,
It was an essential requirement to add a metal such as Co as a binder in the above-mentioned thermal spraying, because the boride or carbide of a certain metal has a high resistance to the molten metal. Although known,
All of them have a high melting point of 2000 ° C or more and are brittle, so depending on the thermal spraying method often used for the surface treatment of relatively large parts such as hot dip galvanizing bath members, the infiltration of molten zinc by using only boride or carbide. This is because it has been conventionally extremely difficult to form a coating having sufficient density to prevent the above.

Therefore, an object of the present invention is to provide a novel alloy having the characteristics that the above coating can be easily formed without using a metal binder such as Co and a method for producing the same, and more specifically. Speaking specifically, a dense film of the above alloy is formed on the surface of the base material to prevent corrosion from molten zinc, and Al added to the bath on the film,
A member which is excellent in corrosion resistance and wear resistance in which Fe and the intermetallic compound with zinc, which is a main component of a bath, eluted from a base material is not deposited and which is used by being immersed in or in contact with molten zinc, and a method for manufacturing the same. To provide.

[0009]

In order to achieve the above object, the inventors of the present invention have conducted a test study of protective coatings made of various materials alone or in combination thereof, and as a result, have a boron content of 3 to 9% by weight, preferably 6%. A Mo-B alloy containing up to 8% by weight and the balance consisting of molybdenum and unavoidable impurities is a material having excellent molten zinc erosion resistance and abrasion resistance, and has excellent suitability for forming the coating for the above purpose. It was discovered that it was an alloy, and the technology of the present invention could be developed. The alloy further contains at least a part of boron M
It has been found that when it has a structural characteristic that it exists as precipitates and dispersions in the dough in the form of oB or Mo ₂ B, it exhibits properties particularly suitable for the above purpose.

The above alloy uses MoB as a starting material and is subjected to explosive spraying or high speed gas flame spraying in a weakly oxidizing atmosphere, or contains 3 to 9% by weight of boron, and the balance is molybdenum and inevitable impurities, Mo in which at least part of boron is present in the form of MoB or Mo ₂ B
It was confirmed that the alloy can be produced by performing plasma spraying using the -B alloy as a starting material and can be easily formed as a direct sprayed coating on the surface of a metal member or the like on which a coating is desired to be formed. Furthermore, it was confirmed that the desired characteristics can be further enhanced by subjecting the thermal spray coating thus formed to an inorganic treatment with water glass or colloidal silica.

An alloy of Mo and B containing a certain amount of boron has an M content in the molybdenum matrix as the boron content increases.
It becomes an alloy in which intermetallic compounds of o ₂ B or MoB are precipitated, and the precipitation phase thereof has a high hardness and contributes greatly to the hardness of the alloy and thus to the wear resistance thereof. The film obtained is a state in which MoB or Mo ₂ B is appropriately deposited in the molybdenum substrate under gas conditions, that is, oxidation conditions. This requires corrosion resistance as well as wear resistance like that of a pot roll of a galvanizing line for steel sheets. It is convenient for the intended use.

It has also been found that the dense coating layer made of the Mo-B alloy is preferably formed by the explosive spraying method using the detonation of acetylene and oxygen, and the residual porosity of 1% or less can be achieved. .

That is, the inventors of the present invention have solved the above-mentioned problems mainly by developing the following alloys and their manufacturing methods, and the members coated with them and their manufacturing methods.

(1) 3 to 9% by weight of boron, preferably 6 to
A molten zinc erosion resistant alloy containing 8% by weight and the balance of molybdenum and inevitable impurities.

(2) The molten zinc erosion resistant alloy according to (1) above, wherein at least a part of boron is present in the form of MoB or Mo ₂ B.

(3) Boron 3 to 9% by weight, preferably 6 to
An alloy for forming a thermal spray coating on the surface of a molten zinc erosion resistant member containing 8% by weight and the balance of molybdenum and inevitable impurities.

(4) Using MoB as a starting material, and by means of an explosive spraying method or a high-speed gas flame spraying method, in a weakly oxidizing atmosphere, that is, in an atmosphere containing sufficient oxygen for the reaction necessary to form the sprayed coating. A method for forming a sprayed coating of a molten zinc erosion resistant alloy containing boron in an amount of 3 to 9% by weight, preferably 6 to 8% by weight, and the balance of molybdenum and inevitable impurities on the surface of the member.

(5) Using a Mo-B alloy containing boron in an amount of 3 to 9% by weight and the balance of molybdenum and inevitable impurities as a starting material, the surface of a metal member is preferably in an amount of 3 to 9% by weight by plasma spraying. Of 6 to 8% by weight, the balance being molybdenum and unavoidable impurities, to form a sprayed coating of a molten zinc erosion resistant alloy.

(6) Using MoB as a starting material, boron is added in an amount of 3 to 3 in a weak oxidizing atmosphere by an explosive spraying method or a high-speed gas flame spraying method, that is, in an atmosphere containing sufficient oxygen for the reaction necessary to form the sprayed coating. A method for forming a sprayed coating of a molten zinc erosion resistant alloy containing 9% by weight, preferably 6 to 8% by weight, and the balance being molybdenum and inevitable impurities.

(7) Molten zinc having a coating layer made of a Mo-B alloy containing 3 to 9% by weight of boron, preferably 6 to 8% by weight on the surface thereof, which has excellent corrosion resistance and wear resistance to molten zinc. Parts to be immersed or contacted.

(8) The member according to the above (7), wherein at least a part of the boron is present in the form of MoB or Mo ₂ B.

(9) The member according to (7) or (8) above, wherein the coating layer is a thermal spray coating.

(10) In the above, the thermal spray coating is subjected to an inorganic sealing treatment with water glass or colloidal silica.
(9) The member described.

(11) Using MoB as a starting material, dipping or contacting with molten zinc characterized by forming a sprayed coating on the surface of a steel member in a weakly oxidizing atmosphere by an explosion spraying method or a high-speed gas flame spraying method. A method of manufacturing a member to be used.

(12) Forming a thermal spray coating on the surface of a steel member by plasma spraying using a Mo-B alloy containing 3 to 9% by weight of boron and the balance of molybdenum and unavoidable impurities as a starting material. A method for producing a member that is immersed in or in contact with molten zinc.

[0026]

In the present invention, the reason why the content of boron in the Mo-B alloy of the coating layer formed on the surface of the member is limited to 3 to 9% by weight is that if less than 3%, MoB precipitated in the molybdenum matrix or On the balance of Mo ₂ B and molybdenum,
This is because the desired corrosion resistance and especially the hardness and thus the wear resistance are not sufficient, and even if the desired corrosion resistance is increased above 9%, the characteristics are saturated and the porosity of the coating layer tends to decrease. It was confirmed experimentally that it is preferably 6 to 8%.

The Mo-B alloy itself according to the present invention is M
Compared to 100% ceramics such as oB, it has excellent toughness because it contains a metal component.

[0028]

Example 1 FIGS. 1 and 2 are sketch diagrams showing the results of a test (reaction between a coating surface and zinc) on a member according to the present invention and a conventional member, and FIG. 3 is a plate subjected to the above test. FIG. 4 is a perspective view of a test sample, and FIG. 4 is a schematic cross-sectional view of a test apparatus used for a reaction test between a coating surface and zinc, which will be described below with reference to these figures.

Zinc particles 4 were placed on a plate-like sample (30 × 30 × 10 mm) 1 as shown in FIG. 3 having SUS403 having a coating layer 3 formed by spraying MoB on one side by explosive spraying as a base material. In the furnace kept in a nitrogen atmosphere by the nitrogen gas introducing hole 9 provided in the furnace body 7, the melting point of zinc is exceeded.
It was heated to 00 ° C. by the heater 6 and kept as it was for 5 hours.

After the test, the zinc particles 4 were not wet with the coating layer 3 at all and remained in a droplet form as seen in the sketch of FIG. No evidence of reaction with zinc was observed on the coated surface.

[0031]

[Comparative Example 1] In the comparative material tested in the furnace at the same time as in Example 1, that is, in the WC-Co coated sample, a clear reaction between zinc and the coating layer was observed, and as shown in the sketch diagram of FIG. Moreover, the wetting angle was determined to be about 20 degrees from the shape of the zinc particles 4.

[0032]

[Embodiment 2] FIG. 5 is a schematic sectional view of a test apparatus used for a zinc bath immersion test using a rod-shaped sample, which will be described below with reference to this drawing.

Using the apparatus shown in FIG. 5, a rod-shaped sample 2 having a diameter of 20 mm and a base material made of SUS403 having a hemispherical tip was spray-coated with MoB to a thickness of 0.12 mm, and the graphite was provided in the furnace body 7. 470 ℃ with heater 6 in crucible 8
It was immersed in the zinc bath 5 kept at 10 days for 10 days.

Although zinc was thinly adhered to the sample 2 when it was pulled up from the bath, it could be easily removed, and after the removal, some oxidation was observed at the site exposed to the atmosphere from the bath surface. However, no change in appearance was observed at the site in the bath before the test.

The above results are summarized in Table 1 for comparison with the conventional material.

[0036]

Comparative Example 2 According to the procedure of Example 2, WC-C was formed on the base material.
A similar test was performed on the rod-shaped sample 2 coated with o. After the test, the entire surface of the sample was thickly covered with zinc, and its removal was difficult. The results are summarized in Table 1 for comparison with the examples.

[0037]

[Comparative Example 3] The same test was performed on the rod-shaped sample 2 coated with pure Mo metal by the plasma spraying method. After 100 hours, the sample was thickly covered with a strongly adherent zinc and its removal was impossible.

[0038]

[Table 1]

[0039]

Example 3 A hardness test and a sliding wear test were performed on the member according to the present invention. FIG. 6 is a perspective view showing the procedure of the ring / disk type sliding wear test, which will be described below also with reference to this figure. (1) Hardness test A sample coated in advance was cut, and the room temperature hardness of its cross section was measured by a Vickers hardness tester, and the results are shown in Table 2. The measurement load was 300 g.

Further, the high temperature hardness was similarly evaluated by a high temperature Vickers tester, and the results are shown in Table 2. (2) Sliding wear test It was measured by the sliding wear test shown in FIG. That is, on the coating layer 3 of the plate-shaped sample 1 to be tested, carbon steel S4
A mating material ring 10 of 5C having an inner diameter of 24.0 mm and an outer diameter of 25.6 mm was placed, and a measuring load of 5 kgf was applied in the direction of the outlined arrow while rotating in the direction of the arrow in the figure.

The test was conducted in the air at room temperature, the sliding distance was 9,800 m (300 rpm for 420 minutes), and the ring and plate samples had surface roughnesses of 0.4 μmRa and 0.5, respectively.
It was μmRa.

The test results are shown in Table 3. In the evaluation of the results, the wear amount was taken as the specific wear amount (mm ² / kg), and the actual wear volume (mm ³ ) was calculated as the sliding distance (mm). The specific wear amount was defined as the value obtained by dividing by the load load (kg).

[0043]

Comparative Example 4 The hardness of SUS304 at room temperature and high temperature (500 ° C. and 700 ° C.) was measured in the same manner as in Example 3, and the results are shown in Table 2.

In the sliding wear test, the specimen was SUS304.
Except for the above, the same procedure as in Example 3 was carried out, and the results are also shown in Table 3.

[0045]

[Table 2]

[0046]

[Table 3]

[0047]

As described above, the member according to the present invention has a coating layer formed on its surface with a Mo-B alloy containing 3 to 9% by weight, preferably 6 to 8% by weight of boron. Explosive spraying method, high-speed gas flame spraying method and plasma spraying method are applied to the formation of, and especially the explosive spraying method can have residual pores of 1% or less.

Further, in the sprayed coating obtained in the present invention, a part of boron is present in the form of MoB or Mo ₂ B, and these are high hardness deposited in the molybdenum substrate as an intermetallic compound, which is a pot roll of the plating line. It is suitable for applications where corrosion resistance and abrasion resistance are required at the same time as body surfaces, bearings, shaft sleeves, or jigs for suspending objects to be plated by immersion plating.

[Brief description of drawings]

FIG. 1 is a sketch diagram showing a test result of a member according to the present invention.

FIG. 2 is a sketch diagram showing a test result of a conventional member.

FIG. 3 is a perspective view showing a plate-shaped sample used for a reaction test between a coated surface and zinc.

FIG. 4 is a schematic cross-sectional view of a test device used for a reaction test between a coated surface and zinc.

FIG. 5 is a schematic cross-sectional view of a test apparatus used for a zinc bath immersion test using a rod-shaped sample.

FIG. 6 is a perspective view showing the procedure of a ring / disk type sliding wear test.

[Explanation of symbols]

 1 Plate-shaped sample 2 Rod-shaped sample 3 Coating layer 4 Zinc particles 5 Zinc bath 6 Heater 7 Furnace body 8 Graphite crucible 9 Nitrogen gas introduction hole 10 Mating material ring

Claims (14)

[Claims] 1. A molten zinc erosion resistant alloy containing 3 to 9% by weight of boron and the balance being molybdenum and unavoidable impurities. 2. At least a part of boron is MoB or M.
The molten zinc erosion resistant alloy of claim 1 which is present in the form o ₂ B. 3. The molten zinc erosion resistant alloy according to claim 1, which has a boron content of 6 to 8% by weight. 4. An alloy for forming a thermal spray coating on the surface of a molten zinc erosion resistant member, which contains 3 to 9% by weight of boron and the balance is molybdenum and unavoidable impurities. 5. A metallic member using MoB as a starting material in a weakly oxidizing atmosphere, that is, in an atmosphere containing sufficient oxygen for the reaction necessary to form the above-mentioned sprayed coating by an explosive spraying method or a high-speed gas flame spraying method. 3-9% by weight of boron on the surface
A method of forming a sprayed coating of a molten zinc erosion resistant alloy containing molybdenum and unavoidable impurities as the balance. 6. A Mo-B alloy containing boron in an amount of 3 to 9% by weight and the balance being molybdenum and inevitable impurities, is used as a starting material, and the surface of a metal member is in an amount of 3 to 9% by weight of boron on a surface of a metal member by a plasma spraying method. A method for forming a sprayed coating of a molten zinc erosion resistant alloy, the balance of which is molybdenum and inevitable impurities. 7. Boron is used in an amount of 3 to 9 with MoB as a starting material in a weak oxidizing atmosphere by an explosive spraying method or a high-speed gas flame spraying method, that is, in an atmosphere containing sufficient oxygen for the reaction necessary to form the sprayed coating. A method for forming a sprayed coating of a molten zinc erosion resistant alloy containing 50% by weight and the balance of molybdenum and unavoidable impurities. 8. The method according to claim 5, wherein the content of boron in the alloy formed as the sprayed coating is 6 to 8% by weight. 9. A Mo-containing surface containing 3-9% by weight of boron.
A member which has a coating layer made of B alloy and which is immersed in or in contact with molten zinc having excellent molten zinc erosion resistance and abrasion resistance. 10. A member according to claim 9, wherein at least a part of the boron is present in the form of MoB or Mo ₂ B. 11. The member according to claim 9, wherein the coating layer is a thermal spray coating. 12. The inorganic sealing treatment with water glass or colloidal silica is applied to the thermal spray coating.
1. The member according to 1. 13. A steel member made of MoB as a starting material in a weakly oxidizing atmosphere by an explosive spraying method or a high-speed gas flame spraying method, that is, an atmosphere containing sufficient oxygen for the reaction necessary to form the sprayed coating. A method for manufacturing a member to be immersed in or in contact with molten zinc, which comprises forming a sprayed coating on the surface. 14. A spray coating is formed on the surface of a steel member by a plasma spraying method using a Mo—B alloy containing 3 to 9% by weight of boron and the balance being molybdenum and unavoidable impurities as a starting material. And a method for producing a member that is immersed in or in contact with molten zinc.