JP2000266055A - Corrosion- and abrasion-resistant sliding member and manufacturing of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sliding member such as a bush, superior in the corrosion- and abrasion-resistances even though it slides while contacting with molten zinc, and its manufacturing method by coating a surface of a sliding member to be treated, with a mixture prepared by mixing WC powder into Ni wax material powder, while sintering the same by a hot isostatic pressing(HIP) method. SOLUTION: As a coating layer is fixed onto a sliding member to be treated by a Ni wax material prepared by melting and solidifying WC powder, WC is superior in the anticorrosion property to molten zinc, and further molten zinc has a large contact angle to WC, so that the molten zinc does not contact with the Ni wax material among WC powder, and the Ni wax material can be prevented from being corroded. Further as the Ni wax material and Ni, Co and the like are diffused in the sliding member to be treated, the coating layer is firmly bonded, and is not separated. Cr in the Ni wax material exists as CrC, and B in the Ni wax material exists as NiB, FeB and the like, so that the hardness of the coating layer can be improved, and the abrasion resistance can be also improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a corrosion- and wear-resistant sliding member having high corrosion resistance and wear resistance to molten zinc and a method for producing the same.

[0002]

2. Description of the Related Art In the case of galvanizing a surface of a steel strip or the like, a method of continuously transferring a cold-rolled steel strip or the like in a molten zinc bath in a tensioned state and plating zinc on the surface is performed. ing. As shown in FIG. 4, the continuous plating line for plating in this manner includes a sink roll 4 that tensions the steel strip 8 and changes the direction as necessary, suppresses vibration of the steel strip 8 during transfer, and controls the transfer direction. Is used as an indispensable member. These rolls 4, 5
As shown in FIG. 5, a bush 7 is mounted on a roll shaft, and a portion of the bush 7 is supported by a bearing 6 so as to be rotatable.

The rolls 4 and 5, the bush 7 and the bearing 6 handle a hard material such as a steel strip 8 in the molten zinc 10. Therefore, the inner surface of the bearing 6, the outer surface of the bush 7 mounted on the roll shaft and The surfaces of the sink roll 4 and the support roll 5 which come into contact with the steel strip are severely abraded, and are considerably corroded and eroded by the molten zinc.

Conventionally, the following method has been implemented as a method for imparting wear resistance and corrosion resistance to such members. (1) Coating a Co-based self-fluxing alloy material by thermal spraying to cover the sliding portion of the sliding member to be processed. (2) WC─10-18% C on the sliding part of the sliding member to be processed
o is coated by high-speed gas flame spraying. (3) The sliding portion of the sliding member to be processed is coated with a stellite-based material by welding.

[0005] However, the mechanism of thermal spray coating after thermal spraying is a method in which molten particles collide with the surface of a base material and are successively laminated to form a metal coating, so that the coated metal particles rapidly rise from room temperature to a temperature higher than the melting point. The material is subjected to a process of colliding with the coating surface to rapidly cool and solidify by colliding with the coating surface. Therefore, the material is liable to be oxidized and deteriorated, and pore-shaped voids are likely to be formed at the metal grain boundaries constituting the coating surface. These voids cause cracks due to impact load due to vibrations of the steel strip, and the cracks are the starting point of zinc erosion. Further, in the high-speed gas flame spray coating method, although the deterioration of the material is relatively suppressed and the generation of pores is small, there is a mechanical weakness of the forming portion of the thermal spraying method.
In addition, a stellite-based material welded overlaid cannot withstand erosion of molten zinc and is difficult to maintain for one week.

[0006]

SUMMARY OF THE INVENTION The present invention provides a corrosion-resistant and abrasion-resistant sliding member such as a bush having excellent corrosion resistance and abrasion resistance even when sliding while contacting with molten zinc, and a method of manufacturing the same. The challenge is to do.

[0007]

Means for Solving the Problems To solve the above problems, the present inventors investigated materials having excellent corrosion resistance and abrasion resistance even when sliding while contacting with molten zinc, coating methods, and the like. In a study, a mixture of a Ni brazing material powder and a WC powder was mixed with hot isostatic pressing (HI
When the surface of the sliding member to be treated is coated while sintering by the P) method, it has been found that this coating layer is extremely excellent in corrosion resistance and wear resistance, and particularly excellent in corrosion resistance to molten zinc. The present invention has been made.

That is, in the method for manufacturing a corrosion-resistant and abrasion-resistant sliding member of the present invention, at least the surface of the sliding portion of the to-be-processed sliding member that comes into contact with the molten zinc is coated with an alloy powder of WC, Ni, Co or the like. In this case, the mixture of the WC-based powder and the Ni brazing material powder is kept in contact with each other and heated and pressed by a hot isostatic pressing method to cover the sintered product of the mixture.

Further, in the corrosion-resistant and abrasion-resistant sliding member of the present invention, a mixture of a WC-based powder and a Ni brazing material powder is hot-statically applied to at least the surface of the sliding portion of the sliding member to be treated which is in contact with the molten zinc. This is to provide a coating layer which is sintered and coated by a pressure forming method. In the corrosion-resistant and abrasion-resistant sliding member of the present invention, the WC-based powder is made of an alloy powder of WC and Ni or Co, and the mixture of the WC-based powder and the Ni brazing material powder is a WC-based powder. 60-90
%, The balance of the Ni brazing material powder.

[0010]

Next, the present invention will be described with reference to the drawings. FIG. 1 is a side view (a) and an A-A cross-sectional view (b) of a bearing manufactured according to an embodiment of the present invention. FIG. 2 illustrates the overall configuration of a hot isostatic pressing apparatus used in the present invention. FIG. 3 is a diagram for explaining an example of heating conditions and pressing conditions in the hot isostatic pressing method of the present invention. The sliding member 2 to be treated of the corrosion-resistant and abrasion-resistant sliding member of the present invention is a cylindrical or semi-cylindrical bearing, a cylindrical bush, a sink roll, or a support covering a portion that comes into contact with a roller shaft bearing. It comes into contact with molten zinc, such as a roll roll, and slides, and its material is carbon steel, low alloy steel,
It is 1200 with steel such as stainless steel, nickel alloy, etc.
Any material may be used as long as it has appropriate strength at a temperature of not more than ℃ and does not extremely soften. The WC-based powder of the mixture coated on the surface of the substrate of the present invention is composed of WC and 5 to 30% by weight of Ni and Co.
It is a powder of an alloy of the like and the like. The reason for using such a WC-based powder is that a strong material in which WC is uniformly dispersed is obtained, and when stainless steel is used as the sliding member 2 to be processed, metallurgical bonding is also obtained.

The Ni brazing filler metal powder mixed with the WC powder is a so-called Ni-based self-fluxing alloy, and is JIS Z 326.
5 is Cr: 1 specified in BNi-1 to BNi-7.
9.5 wt% or less, B: 3.5 wt% or less, Si: 10.5
wt% or less, Fe: 5.0 wt% or less, C: 0.9 wt% or less, P: 12, 0 wt% or less, the balance of Ni powder, etc., for example, Cr: 16 wt%, B: 3.5 wt%, Fe: 2wt%,
C: 0.6 wt%, with the balance being Ni powder. The above WC
The mixture of the WC-based powder and the Ni brazing material powder is 60%.
It is preferable that the Ni brazing material powder has a balance of about 90%. W
If the content of the C-based powder is less than 60%, the hardness of the coating layer coated on the sliding member to be processed using the powder is not sufficient, and
%, The toughness of the coating layer is undesirably reduced. The mixing of the WC-based powder and the Ni brazing material powder may be performed using a ball mill, or another method or apparatus may be used as long as the mixing is sufficient.

Next, a mixture of a WC-based powder and a Ni brazing material powder is hot-coated on the surface (inner surface) of a sliding part of a roll bearing made of ferritic stainless steel as an example of a sliding member, which comes into contact with molten zinc. The method of coating by the hydrostatic molding method will be described. First, the powder to be coated by sintering on the inner surface of the bearing is mixed, and capsules are manufactured in dimensions and shapes taking shrinkage into account by sintering. The capsules are assembled, the mixed powder is filled, the lid is covered, and vacuum removal is performed. After completion of degassing, vacuum sealing is performed, and the resultant is put into a hot isostatic pressing device for processing. The processed capsule is cut by wire cutting, machining or the like to form a sintered coating layer 3 on the inner surface. This is a method of taking out the bearing 1 having the above.

The corrosion-resistant and wear-resistant sliding member of the present invention and the sliding member
Pressurization and heating of hot isostatic pressing in manufacturing method
In an Ar gas atmosphere, as shown in FIG.
00 ~ 1500kgf / cm^TwoPressure, 1050-1150 ° C
Pressing and heating at a temperature of 1 to 3 hours
I can. Sintering pressure 1000 ~ 1500kgf / cm
^TwoTo do 1000kgf / cm^TwoLower is enough sintering
No, 1500kgf / cm^TwoEven with the above, the effect is saturated
This is because that. And the sintering temperature is 1050 ~ 1150 ℃
If the temperature is lower than 1050 ° C, sintering will not be sufficient and
If the temperature is higher than 1150 ° C., the treated sliding member of the base material deteriorates.
This is because that.

Further, a hot isostatic pressing apparatus used in the hot isostatic pressing method used in the corrosion-resistant and abrasion-resistant sliding member of the present invention and the method for manufacturing the same is provided with, for example, an object to be processed as shown in FIG. Pressurized and heated for sintering body 11, gas supply 1
4, comprising a vacuum pump 19, a transfer device 20, a heating power control device 21, etc., the main body 11 is held by a press frame 18, and comprises a pressure vessel 12, a Mo heater 13, etc. Gas equipment 14 for supplying Ar gas, etc.
Are the Ar gas storage container 15, the pressure regulator 16, the gas compressor 17
It is made up of

[0015]

The corrosion-resistant and abrasion-resistant sliding member of the present invention has a coating layer of W
WC is not corroded because it has excellent corrosion resistance to molten zinc because it is fixed to the sliding member to be processed by the Ni brazing material that has melted and solidified the C-based powder. Further, since the molten zinc has a large contact angle with respect to WC, it does not come into contact with the Ni brazing material between the WC powder and the WC powder, and the Ni brazing material does not corrode. Further, since the Ni brazing material, Ni, Co, and the like are diffused into the sliding member to be processed, the coating layer is firmly bonded and does not peel off. In addition, since the structure of the coating layer is dense, unlike a thermal sprayed coating, there is no pore or trachea, which is a starting point of wear, so that wear is small. In addition, Cr in Ni brazing material
Is CrC, B is NiB, FeB or the like to increase the hardness of the coating layer and increase the wear resistance.

Next, an embodiment of the present invention will be described.

Example 1 80% by weight of WC-20% Ni powder and 0.6% by weight of C-1
20 wt% of 6 wt% Cr-2 wt% Fe {3.5 wt% B} balance Ni alloy powder was mixed in a ball mill, and the mixture powder was used to form a ferrite stainless steel having a diameter of 200 wt.
mm, the mixed powder is vacuum-sealed in a capsule through the same process as in FIG. 2 on the inner surface of a cylindrical bearing 2 having a thickness of 15 mm,
It was loaded into the same hot isostatic press as in FIG. 3 and heated and pressurized in an Ar gas atmosphere.

Heating is performed from room temperature to 800 as shown in FIG.
To 400 ° C at a heating rate of 400 ° C / hour.
After holding for a time, heat to 1050 ° C. at the above heating rate,
It was kept at the same temperature for 2 hours and cooled at a cooling rate of 125 ° C./hour. Pressing conditions were such that when the heating temperature reached 1050 ° C., the pressure was gradually increased to 1000 kgf / cm ² ,
The pressure was maintained at 0 kgf / cm ² for 2 hours, then the pressure was gradually reduced to 150 kgf / cm ² , and then the pressure was rapidly reduced to the atmospheric pressure.

Thereafter, the bearing and the capsule are taken out of the hot isostatic pressing apparatus, and the capsule is machined and cut.
The bearing 1 shown in FIG. The thickness of the coating layer 3 of the bearing 1 was 3 mm as expected. The bearing 1 was mounted on a galvanizing apparatus currently in operation and used for 20 days, and the amount of wear was measured. After 14 more days of use, the amount of wear was measured and found to be 0.1
mm. Since the thickness of the coating layer is 3 mm,
The expected life is about 150 days. In contrast, the currently used Co-based alloy sprayed product had a life of 14 days.

Example 2 A mixture of ferrite stainless steel was prepared using the same mixture powder as in Example 1 and under the same coating conditions as in Example 1.
A test piece having a 3 mm coating layer on a steel plate of 0 mm (width) × 60 mm (length) × 9 mm (thickness) was manufactured. The test piece was subjected to a bath temperature test using a molten zinc bath shaft component tester (a device for fixing the test piece in a molten zinc bath and pressing the test piece while rotating a Co alloy cylinder while measuring the wear amount). : 460 ° C, rotation speed: 100rpm, load: 100k
g, the result of measuring the amount of wear under the condition of the partner material: Co alloy was as follows. Further, a comparative example in which a Co-based self-fluxing alloy was sprayed on a base material by 3 mm and Stellite No. 6
The results of measuring the wear amount under the same conditions with respect to the comparative example in which the mm welding build-up was performed were as follows. Product of the present invention: 76 μm / hr Co-based self-fluxing alloy sprayed (Comparative Example): 124 μm / hr Stellite No. 6 weld-welded (Comparative Example): 231 μm / hr

From these results, it was found that the product of the present invention was about 11 times as large as the currently used Co-based alloy sprayed product when mounted on a galvanizing apparatus currently in operation. In a test using a molten zinc bath shaft component tester, a test piece manufactured by the same method as the method of the present invention had a stellite No. 6 welded to about 1.6 times that of a sprayed Co-based self-fluxing alloy. It was about three times.

In the above embodiment, the surface of the sink roll and the surface of the support roll in contact with the outer surface of the bush and the steel strip are not described, but the result is the same as that of the bearing.

[0022]

According to the present invention, the above-described configuration enables
Corrosion due to the molten zinc can be reduced, and since it is hard, the amount of wear can be reduced, so that there is an excellent effect that the life can be extended.

[Brief description of the drawings]

FIG. 1 is a side view of a bearing manufactured in an embodiment (a) and AA.
It is sectional drawing (b).

FIG. 2 is a conceptual diagram for explaining the overall configuration of a hot isostatic pressing apparatus.

FIG. 3 is a diagram for explaining a heating condition and a pressing condition of the present invention.

FIG. 4 is a conceptual diagram illustrating a hot-dip galvanizing apparatus.

5 is a cross-sectional view illustrating a bearing structure of a sink roll and a support roll of the hot dip galvanizing apparatus of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Corrosion-resistant wear-resistant sliding member (bearing with coating layer) 2 Sliding member to be processed (bearing) 3 Coating layer 4 Sink roll 5 Support roll 6 Bearing 7 Bush 8 Steel strip 9 Wiping nozzle 10 Melted zinc 11 Hot static Hydraulic molding machine body 12 Pressure vessel 13 Mo heater 14 Gas equipment 15 Ar gas storage vessel 16 Pressure regulator 17 Gas compressor 18 Press frame 19 Vacuum pump 20 Transport device 21 Heating power control device

Claims (4)

[Claims] 1. A mixture of a WC powder and a Ni brazing material powder is brought into contact with at least the surface of a sliding portion of a sliding member to be treated which is in contact with molten zinc, and is heated and pressed by hot isostatic pressing. A method for producing a corrosion-resistant and abrasion-resistant sliding member, comprising: 2. A mixture of a WC-based powder and a Ni brazing powder is sintered and coated by hot isostatic pressing on at least the surface of the sliding portion of the sliding member to be treated (2) which comes into contact with molten zinc. A corrosion-resistant and wear-resistant sliding member provided with a coating layer (3). 3. The corrosion-resistant and wear-resistant sliding member according to claim 2, wherein the WC-based powder is a powder of an alloy of WC and Ni or Co. 4. The method according to claim 2, wherein the mixture of the WC-based powder and the Ni brazing material powder contains 60 to 90% of the WC-based powder, and the balance is the Ni brazing material powder. Corrosion- and wear-resistant sliding member.