JP2010150664A - Immersion member for hot-dip metal plating bath - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an immersion member for a hot-dip metal plating bath in which the durability against thermal shock and repeated thermal fatigue are substantially improved and the replacement work at the time of wear and breakage is remarkably simplified. <P>SOLUTION: The immersion member 3 for the hot-dip metal plating bath is provided in a pot roll device that is immersed in the hot-dip metal plating bath. The immersion member 3 is a silicon-carbide-based ceramic member and is fitted to a part or the whole of a sliding part of at least a sleeve member of a pot roll shaft part or a bearing member of the pot roll device. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an immersion member for a molten metal plating bath in a continuous molten metal plating apparatus such as a steel plate.

  As shown in FIG. 1, as a method for obtaining a metal plating plate, a metal plate heated and annealed in a heating furnace is guided to a molten metal tank, the molten metal is plated on the metal plate, and this is passed through a pot roll and a guide roll. A method of continuously obtaining a metal plating plate by pulling up is widely used. More specifically, in the case of using a steel plate as the metal plate, the plating method on the metal plate by the continuous molten metal plating apparatus inserts the steel plate whose surface has been cleaned and activated as a pretreatment into the molten metal bath, After changing the direction with the pot roll, the sheet is passed between two guide rolls in order to suppress warpage in the width direction of the steel sheet. Thereafter, the steel plate is further lifted upward, and excess molten metal adhering to the surface of the steel plate immediately above the plating bath is removed by high-pressure gas wiping, etc., and adjusted to a predetermined plating amount to produce a hot-dip metal plated steel plate. To do.

  Generally, 24Cr-12Ni stainless steel having good corrosion resistance is used for the bearing member and the shaft sleeve member of the pot roll immersed in the molten metal plating bath. Stainless steel has low reactivity with molten metals such as molten zinc and molten aluminum, and has good corrosion resistance, but it cannot be said to have sufficient wear resistance. In particular, the bearing member is extremely narrow compared to the shaft sleeve member. Since the contact is always made in the range (the upper half), the wear amount is larger than that of the shaft sleeve member, and the life is as short as about 4 to 8 days. As wear of the bearing member progresses, fluttering or the like occurs on the steel sheet, and satisfactory plating cannot be performed. Therefore, the member must be lifted from the molten metal plating bath and the bearing member must be replaced. Therefore, even if there is no abnormality in other members such as a pot roll immersed in the molten metal plating bath, it is necessary to stop the operation and pull up the entire component immersed in the molten metal plating bath. At this time, since it is cooled rapidly from the bath temperature to room temperature, damage such as thermal shock breakage may occur in other parts, and the entire part may be replaced in a lump, and production loss is extremely large. . For this reason, various proposals have been made to extend the life of rolls used in a molten metal plating bath.

  In Patent Document 1 and Patent Document 2, proposals have been made to use alumina or silicon nitride sialon for the bearing member and shaft sleeve member in the molten zinc bath, and to rotate and rotate the rotating pot roll from the outside. However, in this proposal, only zinc is taken as the molten metal, and only the sliding wear amount and the wear coefficient are used as selection criteria, and the thermal shock resistance and wettability with the molten metal are not considered. Further, regarding alumina / sialon ceramics, there is no description of optimum conditions for various properties such as composition, firing conditions (density, structure), mechanical properties, and sliding surface roughness.

  Monolithic silicon carbide and zirconia ceramics are known to be inferior in thermal shock to sialon.

JP-A-3-253547 JP-A-5-44002

  The above-mentioned technology relating to the sliding bearing is such that the surfaces of the bearing member and the shaft sleeve member that are in contact with each other have better corrosion resistance in a molten metal bath than stainless steel, and are coated with a high-hardness ceramic, or By using cermet, cemented carbide, ceramic sintered body, etc., it is intended to extend the life of the bearing. However, the optimum combination of the bearing member and the shaft sleeve member is a much more important selection factor for the member for the molten metal plating bath, considering the material's characteristics such as thermal shock resistance, high toughness, and poor wettability. . It is indispensable to increase the durability against thermal shock and repeated thermal fatigue associated with air cooling at the time of pulling up the pot roll heated to several hundred degrees Celsius, and to control the wettability with respect to molten aluminum among molten metals.

  Moreover, since the opportunity loss in operation can be reduced if the replacement operation can be performed quickly, it is also desired that the member can be replaced easily.

  Accordingly, an object of the present invention is to provide an immersion member for a molten metal plating bath that greatly improves durability against thermal shock and repeated thermal fatigue, and at the same time, remarkably simplifies replacement work when worn or damaged. .

The present invention has been made for the purpose of providing an immersion member for a molten metal plating bath that can be used stably and repeatedly in a molten metal plating bath for a long time and can be easily replaced during replacement work. Yes,
(1) An immersion member attached to a pot roll apparatus immersed in a molten metal plating bath, wherein the immersion member is at least a portion of the pot roll facility where the pot roll shaft sleeve member and the bearing member slide. A silicon carbide-based ceramic member that is partially or entirely fitted, wherein the ceramic member is a volume fraction of a composite metal boride in which the ceramic member is a Ti-Zr-B solid solution and / or a Ti-Hf-B solid solution. A silicon carbide sintered body containing 20 to 70% by mass, and a sintered body density of 95% or more of the theoretical density;
(2) The immersion member for a molten metal plating bath according to (1), wherein the immersion member includes a plurality of columnar members,
(3) The immersion member for a molten metal plating bath according to (2), wherein the columnar member is fitted in the axial direction of the bearing portion,
(4) The immersion member for a molten metal plating bath according to (3), wherein the sliding surface in the rotation direction of the columnar member is a flat surface or an arcuate surface having a radius of curvature of the pot roll shaft sleeve member,
(5) The immersion member for a molten metal plating bath according to (2), wherein the columnar member is fitted to the pot roll shaft sleeve member in the axial direction.
(6) The immersion member for a molten metal plating bath according to (5), wherein the sliding surface of the columnar member is an arc-shaped surface having a radius of curvature of the bearing member or less.
(7) The axial sliding surface of the columnar member has a concavo-convex shape and / or a corrugated shape, and the height of the sliding surface of the convex portion is aligned in the axial direction. The dipping member for a molten metal plating bath is used as a gist.

  By this invention, the lifetime of the bearing member in a continuous molten metal plating apparatus can be extended significantly. This makes it possible to produce a metal-plated steel sheet stably for a long time, and its industrial utility is very large.

Equipment cross-sectional schematic diagram of hot dipping bath Longitudinal sectional view and rotational axis sectional view of the embedded member Assembly structure diagram of bearing Device sectional view at the time of bearing wear evaluation according to an embodiment of the present invention

  The present inventors reviewed the roll bearings in the molten zinc bath proposed in Patent Document 1 and Patent Document 2, and even in the molten aluminum bath having a higher melting point than zinc, sliding wear and thermal fatigue that were difficult in the prior art Bearing members that can suppress chipping and cracking around the part, have excellent durability against mechanical shock when landing after pulling up the roll, and thermal stress repeatedly applied by taking out from the bath and air cooling The structure, shape and material were found. These chipping and cracking defects are generated and propagated by thermal shock and mechanical shock. When there are many holes in the member, low strength, low toughness, and good wettability with molten metal , Low thermal conductivity, low thermal shock, when the sliding surface is rough, etc., and sliding wear is remarkable when the sliding part is not a surface but a line contact or a point contact It was confirmed that it was suppressed.

  The immersion member for a molten metal plating bath of the present invention is an immersion member attached to a pot roll device immersed in a molten metal plating bath, and the immersion member is at least a pot roll shaft sleeve member of the pot roll facility or This is a silicon carbide ceramic member that is fitted to a part or all of the sliding portion of the bearing member. The immersion member for the molten metal plating bath is preferably a silicon carbide ceramic from the viewpoint of high thermal shock resistance, high toughness, and high wear resistance.

  Moreover, it is preferable to fit a plurality of columnar members from the viewpoint of easy handling of the immersion member. As for the embedded shape, the surface that slides directly with the pot roll is preferably a flat surface or an arcuate surface that is convex above the radius of curvature of the pot roll shaft sleeve member, but there is no particular limitation, and the cross section is perpendicular to the axis. The shape may be a polygon more than a quadrangle, a semicircle, or a circle. It is not preferable to arrange the columnar members in the rotation direction. In order to limit the compressive stress load, it is recommended to arrange line contact and point contact in the same direction as the rotation direction. In addition, an arcuate surface that is convex upward or less than the radius of curvature of the pot roll shaft sleeve member or a concave arcuate surface that is greater than or equal to the radius of curvature loads the embedded material other than compressive stress, and has a higher probability of failure than compression. It is expected to be. Preferably, if a ceramic bearing piece having an isosceles trapezoidal cross section whose lower side is longer than the upper side is used, positioning is easy without using wedges or adhesives, and only compressive stress is used. Can be loaded. Furthermore, as shown in iii) to iv) of FIG. 2, it is possible to change from line contact to point contact by sequentially providing irregularities or corrugations in a direction parallel to the rotation axis of the columnar embedding material, Since the flow of the plating bath can be promoted, it is assumed that the rotation becomes smooth. Whether the unevenness or corrugated pattern with the adjacent embedding material should be reversed or in phase should correspond to the flowability of the plating bath and the number of rotations of the pot roll. By adopting such a shape, it becomes difficult to collect molten metal at the bearing portion, and work efficiency such as repair work can be improved.

  In addition, regarding the sliding portion of the rotating shaft member of the pot roll, the same ceramic material or cemented carbide particles as the bearing member may be dispersed in a binding metal (a binder such as copper, titanium, or zinc). Also in this case, if the curvature on the bearing side is not larger than the curvature of the shaft, as described above, a tensile stress to be applied to the bearing member is applied, which is completely inappropriate. If it is flat or arcuate, processing is easy, and if the curvature is large, it is easily expected that the stability of the rotating shaft on the pot roll side will slightly increase. Further, when fitting to the rotating shaft, if the curvature of the embedded material on the rotating shaft side is larger than the curvature of the bearing, the shape of the embedded material becomes extremely large or too thin, which is not preferable.

  And by making this member into the above-mentioned shape, the absolute value of the expansion / contraction difference in the bath and air cooling caused by the difference in thermal expansion coefficient with the metal member fitted to the member can be reduced, and compression applied to the ceramic side Or, in addition to reducing the tensile stress, it has the effect of facilitating densification in manufacturing the ceramic member. The member to be fitted has a thickness of 5 mm or more and 20 mm or less, and preferably two or more columnar members are used. When the thickness is less than 5 mm, the compressive strength of the ceramic member is low, and the wear mark generated on the sliding surface after use is polished, and the total life is shortened when recycled, which is not preferable. If only one columnar member is used, stability at the time of rotation is not obtained at all, which is not suitable. Moreover, the range of 5-20 mm thickness is preferable also from the point of intensity | strength provision with respect to the mechanical impact at the time of handling a roll arm. About width, although depending on the size of the pot roll diameter and the number of the fitted columnar members, 10 to 30 mm is preferable. Further, the length of the columnar member is uniquely determined by the sleeve length of the metal member into which the member is fitted. Generally, a thickness of about 80 to 200 mm is often used.

  As shown in FIG. 3, in order to reduce the compressive or tensile stress caused by the difference in thermal expansion coefficient from the molten metal caught in the gap between the metal ring member used to hold the ceramic bearing, The gap between the fitting part between the member and the metal member is preferably 1 mm or less.

  Contrary to the above, it is also possible to fit a columnar member having a circular arc-shaped surface having a bearing portion which is a circular integral part and having a convexity lower than the curvature of the bearing to the pot roll shaft portion sleeve. However, care must be taken to ensure that sufficient fixing strength is obtained when embedding in the bearing part.In order to reduce the frictional resistance when the bearing part comes into contact, the sliding part is not a flat surface but has a curvature larger than the inner diameter of the bearing part. A small arcuate curved surface is most preferred. Furthermore, it is necessary to fit over the entire circumference, and stable rotation can be obtained with 2 or more, preferably 3 or more, more preferably 5 or more. If the number is less than two, the chance of sliding on the portion other than the columnar member is increased, and the metal shaft sleeve material is selectively worn away from the columnar member, so that the extension of the life cannot be expected.

As a method for simultaneously improving characteristics such as low wettability with molten metal, high thermal conductivity, high thermal shock, and wear resistance, in a sufficiently dense SiC or Si ₃ N ₄ sintered body, the second phase (Ti—Zr— It is effective to control the structure of the sintered body by forming a B solid solution or a chromium compound typified by Cr ₂ N or the like. Such a sintered body structure can simultaneously provide an effect of significantly improving chipping resistance, such as chipping and cracking, from a bearing made of a monolithic sialon described in the prior art. Metal composite borides represented by Ti _x Zr _y B ₂ have the effect of increasing toughness and hardness by dispersing in a silicon carbide sintered body, and dramatically improve fracture resistance and wear resistance. Improve. On the other hand, it has the effect of reducing wettability to molten metal.

Regarding the surface roughness of the sliding portion, it is effective to finish R _max ≦ 0.2 μm in order to prevent molten aluminum from adhering and to reduce the dynamic friction coefficient. If it exceeds 0.2 μm, even if the wettability with molten aluminum is low, the adhesion ratio increases mechanically and the dynamic friction coefficient is remarkably increased, which is not preferable. In contact with a flat surface or a convex arc surface, machining is relatively easy, and even finishing with R _max ≦ 0.1 μm is often excellent in terms of cost effectiveness.

  In addition, as the columnar member shape of the embedding material (FIG. 2), if it is a simple flat surface or circular arc surface, and also has a concavo-convex or corrugated shape in the longitudinal direction, it can be given by simple grinding, so the cost of finishing the sintered body The life of the member for a molten metal plating bath can be extended without increasing the thickness.

Silicon carbide (SiC) is a substance having a strong covalent bond, and it is difficult to sinter in atmospheric inert gas (such as Ar) by itself. These additives may be added. The theoretical density ratio of 95% means a sintered body structure in which open pores are almost eliminated and closed pores are dominant, and it prevents the penetration of the plating bath into the member and significantly reduces the wear rate. This is a possible density region. As the sintering aid, for example, carbon black, various borides, alumina, an organic substance that can be a carbon source, aluminum carbide, aluminum nitride, and the like can be used. As the sintering aid, for example, silica, alumina, yttria, tetrairon iron oxide, magnesia, AlN—Si ₃ N ₄ —SiO ₂ —Al ₂ O ₃ eutectic, aluminum nitride, various rare earth oxides, etc. are used. be able to.

  As a sintering method, any of a normal pressure (no pressure) sintering method, a gas pressure sintering method, a hot isostatic pressing sintering method, and a hot pressing method can be used. It is also possible to combine a plurality of sintering methods. If the normal pressure sintering is performed in a nitrogen gas or Ar gas flow, a dense sintered body is easily obtained. In order to achieve high density in a molten metal bath member having a complicated shape, hot isostatic pressing sintering may be performed in a nitrogen gas or Ar gas pressurized atmosphere after atmospheric pressure sintering. preferable. Among them, the range of the maximum temperature during normal pressure sintering is preferably 1900 to 2150 ° C. for silicon carbide, and the holding time at the maximum temperature is preferably 2 hours or more. In the case of silicon carbide, if it is less than 1900 ° C., a sufficiently high density (relative density ≧ 95%) cannot be obtained, the particle dispersion effect is not sufficiently exhibited, and a high fracture toughness value cannot be obtained. Moreover, abnormal grain growth may occur at a temperature higher than 2150 ° C., which is not preferable.

  For silicon carbide-based ceramics, if the metal composite boride is dispersed in the sintered silicon carbide in a volume fraction of less than 20% by volume, the toughness is insufficient, and if the volume fraction exceeds 70% by volume, it is normal pressure. Densification with a relative density of 95% or more during sintering is difficult, and the original hardness and high temperature strength of silicon carbide cannot be obtained, which is not preferable. Further, due to differences in thermal expansion and Young's modulus between silicon carbide and Ti-Zr-B solid solution particles and / or Ti-Hf-B solid solution particles, dispersed Ti-Zr-B solid solution particles and / or Ti-Hf. -B Residual stress is generated in the vicinity of the solid solution particles, and has the function of dispersing the fracture energy when the sintered body is broken, and has the effect of significantly improving toughness and wear resistance. As the chemical compound, Ti-Zr-B solid solution particles and Ti-Hf-B solid solution particles are suitable.

  These Ti-Zr-B solid solution particles and / or Ti-Hf-B solid solution particles are hard and oxidation-resistant high melting point compounds having an hcp structure, and are dispersed as dispersed particles in a silicon carbide sintered body after sintering. It remains and has the effect of improving the hardness and fracture toughness of the entire sintered body.

The composition of the Ti-Zr-B solid solution particles and / or Ti-Hf-B solid solution particles are respectively expressed by _{Ti 1-x Zr x B 2} , Ti 1-x Hf x B 2, x ranges 0.02 -0.25 is preferable, More preferably, it is 0.02-0.05. When the the TiB ₂ solid solution of ZrB ₂ and HfB _2, compared with the TiB ₂ alone, hardness and fracture toughness value increases. However, if x is smaller than 0.02, the solid solution effect of Zr and Hf in TiB ₂ becomes poor, and there is a risk that sufficient hardness cannot be achieved. On the other hand, when x exceeds 0.25 Since the thermal expansion coefficient of the matrix is different from that of silicon carbide, it becomes difficult to be densified during sintering, and a sintered body having a low relative density is likely to be formed, and the fracture toughness value is likely to be lowered. The average particle size of the solid solution particles is preferably 1 to 10 μm. More preferably, it is 3-5 micrometers. If the average particle size is smaller than 1 μm, it is difficult to obtain a contribution to toughness, while if it is larger than 10 μm, the hardness and fracture toughness value tend to be lowered.

  Next, examples of the present invention will be described together with comparative examples.

(Examples 1 and 2)
Silicon carbide (SiC) powder (α-type, purity 98.5%, average particle size 0.4 μm), titanium boride (TiB ₂ ) powder (average particle size 3.5 μm), zirconium boride (ZrB ₂ ) powder ( A predetermined amount (mass%) shown in Table 1 was added to boron carbide (B ₄ C) powder (average particle size 1.5 μm), carbon black powder (average particle size 0.02 μm), average particle size 5.5 μm), Purified water was used as a dispersion medium at the time of kneading and kneaded for 24 hours by a ball mill. The amount of purified water added was also 100 g with respect to 100 g of all ceramic powder raw materials.

  Next, the obtained mixed powder was molded and then sintered. The molding conditions were a pressure of 150 MPa by cold isostatic pressure, and a plate-like molded body having a 100 mm square and a height of 22 mm was obtained. As sintering conditions, nitrogen gas or Ar gas circulation was performed, and pressureless sintering maintained at each temperature shown in Table 1 for 4 to 8 hours and hot isostatic pressing sintering were added as necessary. .

  From the obtained sintered body, a fixed-side bearing test material of 15 mm × 20 mm × length 80 mm was ground and subjected to a bearing test in a molten aluminum bath (FIG. 4).

A test piece for evaluating mechanical properties was cut out from the remaining material when the test material of 15 mm × 20 mm × length 80 mm was cut out from the plate-like sintered body, and its characteristics were evaluated. The hardness was measured as Vickers hardness at an indentation load of 10 kg. Regarding toughness, the fracture toughness value K _IC was measured at room temperature by the SEPB method of JIS R1607. The thermal shock resistance was evaluated based on a rapid cooling temperature difference ΔT at which a bending test piece was heated to a predetermined temperature in the air and then rapidly cooled in water, and the bending strength began to deteriorate. The sintered body density was measured as a relative density by the Archimedes method. The wettability was measured by the contact angle between a normal molten droplet and a horizontal plate.

  Table 2 shows the Archimedes density, mechanical properties, and results of bearing evaluation in the aluminum bath shown in FIG. 4 for each blended system. The test in the aluminum bath was performed under the following conditions.

(1) Rotating side bearing test material: Carbide ring material φ90mm x Height 60mm
(2) Fixed side bearing test material: 3 ceramic test materials 15 mm x 20 mm x 80 mm length (3) Molten aluminum temperature: 680 ° C
(4) Pushing force: 30-50N
(5) Sliding speed: 2 to 3 m / sec (6) Sliding time: 1 hour after immersion (7) Finished surface roughness before test: R _max = 0.2 μm (about ΔΔΔΔ, see JIS B0031) )
(8) Repeated thermal fatigue test: after being immersed in a bath for 1 hour, then pulled up from the bath and repeated air cooling for 30 minutes. After melting, observation measurement from outside the furnace through a viewing window As a method for obtaining the wear amount under the conditions (1) to (7) above, the depths h _r and h _s of the wear traces generated on the rotating side and the fixed side are determined. Measured with a surface roughness meter. In addition, the presence or absence of damage around the wear trace, the chipping depth, and the crack depth were evaluated by a fluorescent flaw detection method and observation of the cross-section polished surface with an optical microscope. The required amount of grinding of the bearing-sliding surfaces for reuse is 1.2 times the wear trace depth h when no cracking or chipping damage is observed around the wear trace. When cracking occurs 1.2 times, it is shown in Table 2 as 1.2 times the crack depth.

(Comparative Example 3)
Comparative example 3 is a comparative example in which a part of the ring is fitted into a bearing using known silicon carbide. The material of this comparative example was also tested in a molten aluminum bath under the same conditions as in Examples 1 and 2, and the results are shown in Table 2.

  As shown in Table 2, according to the embodiment of the present invention, the wear trace depth is very small at 25 μm or less on both the fixed side and the rotation side, and there are no cracks or chipping defects around the wear trace. In some cases, the wear resistance and fracture resistance are excellent, but each bearing of the comparative example has a wear trace depth of 60 μm or more larger than that of the embodiment of the present invention, and either cracking or chipping occurs. It was confirmed that neither wear resistance nor fracture resistance was achieved. The required amount of grinding was found to be remarkably large at 72 μm or more in the comparative example as compared to 30 μm or less in the example.

  Table 3 shows the results based on the conditions (8) and (9) of the bearing evaluation test in the aluminum bath.

  Even when the bearing is repeatedly subjected to thermal fatigue, the one according to the present invention can be used 20 to 30 times, whereas each material of the comparative example is 5 to 10 times and less than half. Considering the processing cost at the time of regrinding and the total life of the product including repeated use, it was confirmed that the bearing material made of the sintered body of the present invention is extremely advantageous. Further, in the wettability evaluation, it was found that the material according to the present invention was not easily wetted at 105 to 135 °, and that each material of the comparative example had a small contact angle of 40 to 50 ° and was easily wetted. The effect of reducing the tensile stress to the fixed side is sufficiently expected when the corrosion resistance is improved and the thermal contraction due to air cooling during pulling occurs. For this reason, it is easily estimated that it is difficult to get wet with molten aluminum and that it has a high durability against repeated thermal fatigue. It is thought that it did not occur. From the evaluation results in the high-temperature aluminum bath, it can be easily assumed that the thermal shock resistance in the lower-temperature zinc bath is also satisfied. Therefore, it can be determined that the present invention can be applied to a member for a molten metal plating bath.

1 Steel plates being passed through the plating line,
2 pot rolls,
3 guide rolls,
4 Bathtub with heating function,
5 Rotating side bearing test material (φ90mm × height 50mm),
6 Fixed side bearing test material (15 mm x 20 mm x length 80 mm),
7 Molten aluminum bath (680 ° C),
8 Thermocouple with protective tube.

Claims (7)

  A dipping member attached to a pot roll apparatus immersed in a molten metal plating bath, wherein the dipping member is a part of a sliding part of at least a pot roll shaft sleeve member and a bearing member of the pot roll equipment or A silicon carbide-based ceramic member that is entirely fitted, wherein the ceramic member is a Ti-Zr-B solid solution and / or a Ti-Hf-B solid solution composite metal boride in a volume fraction of 20 An immersion member for a molten metal plating bath, characterized in that it is a silicon carbide sintered body containing ˜70% and has a sintered body density of 95% or more of the theoretical density.   The immersion member for a molten metal plating bath according to claim 1, wherein the immersion member includes a plurality of columnar members.   The immersion member for a molten metal plating bath according to claim 2, wherein the columnar member is fitted in the axial direction of the bearing portion.   The immersion member for a molten metal plating bath according to claim 3, wherein the sliding surface in the rotation direction of the columnar member is a flat surface or an arcuate surface having a radius of curvature of the pot roll shaft sleeve member.   The immersion member for a molten metal plating bath according to claim 2, wherein the columnar member is fitted to the pot roll shaft sleeve member in the axial direction.   The immersion member for a molten metal plating bath according to claim 5, wherein the sliding surface of the columnar member is an arcuate surface having a radius of curvature of the bearing member.   6. The molten metal plating bath according to claim 3, wherein the sliding surface in the axial direction of the columnar member has an uneven shape and / or a wave shape, and the sliding surface height of the convex portion is aligned in the axial direction. Immersion member.