JP3203586B2 - Wear-resistant carbon roll and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
Roll cooling, or a wear-resistant carbon roll used for electric heating and a method for manufacturing the same, particularly, a thermal roll based on temperature distribution does not occur even when contacted with a high-temperature metal material, and a carbon roll excellent in wear resistance and It relates to the manufacturing method.

[0002]

2. Description of the Related Art Hearth rolls in a furnace used for annealing metal, for example, continuous annealing of cold-rolled steel sheets, have a high ambient temperature of the furnace, and when the steel sheet in contact with the furnace is lower than the ambient temperature, the center of the roll has a temperature. And the edge of the roll is hotter and has a temperature distribution. In response to this temperature distribution, the profile of the roll will have a concave crown with a central dent and high edges due to thermal expansion. Conversely, when contacting a steel sheet that is higher than the furnace ambient temperature, or when using a cooling roll used to cool a heated steel sheet, or an energizing roll or holding roll used for energizing heating, the roll temperature is lower than that of the steel sheet. The temperature of a portion that is in contact with a high-temperature steel plate is heated to a high temperature, but the temperature of a portion that is not in contact with the steel plate is low, and a convex crown is formed. In such a state, a temperature distribution and a tension distribution are easily formed on the steel sheet, and the shape is deteriorated, so that an ear wave and a diaphragm are easily generated. In addition, when the width of the steel sheet changes, the profile of the roll changes, and the shape of the steel sheet tends to become unstable.

[0003] Further, when a crown is formed on an energizing roll or a holding roll, a contact pressure to the steel sheet is partially reduced, and as a result, a spark is generated between the steel sheet and the energizing roll, and the steel sheet,
There has been a problem that melting marks are formed on both of the current-carrying rolls, resulting in a reduction in product quality and a reduction in roll life.

[0004] As described above, if the roll profile changes, various inconveniences may occur. To make the roll surface temperature uniform, Japanese Patent Application Laid-Open No. 57-136793 discloses a high magnetic flux density on the roll surface. It is described that a conductive magnetic film is formed so as to increase the resistance value of a portion, and induction heating is performed to obtain a uniform temperature distribution. Japanese Patent Application Laid-Open No. 61-79733 discloses a transport roll in which the surface of the roll body is made of conductive ceramic and can be heated by electricity. It is described that this roll can make the temperature distribution in the width direction of the roll uniform by resistance heating by supplying electricity to the conductive ceramic.

[0005]

However, even if only the roll surface temperature is to be made uniform as in these prior arts, the roll surface temperature distribution is still non-uniform if a material different from the roll surface temperature comes into contact with the roll. At the same time, since heat is transferred from the bearing to the roll to each part, it is difficult to make the temperature uniform inside the roll, and it is difficult to make the roll profile uniform.

[0006] When the roll itself becomes hot due to contact with a high-temperature atmosphere or a high-temperature object, oxidation of the roll itself becomes a problem. JP-A-3-
The graphite roll described in Japanese Patent No. 211219 has an atmosphere temperature of 40.
Although it shows excellent oxidation resistance in the range of 0 to 1200 ° C, it does not specifically mention the wear resistance required for such applications.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a carbon roll which hardly generates uneven temperature distribution on the roll surface, can prevent the occurrence of a thermal crown, and has abrasion resistance, and a method for producing the same.

[0008]

The gist of the present invention is as follows.
~ It is as follows.

[0009]

[0010]  TiN or TiC in base carbon
Wear-resistant carbon characterized by dispersing particles of
roll.

[0011]  Metal oxide in micropores of base metal carbon
Filled withSaidWear-resistant carbon roll.

[0012]  The metal oxide is ZrO_Two ・ SiO_Two Also
Is 3Al_Two O_Three ・ 2SiO_Two IsSaidAbrasion resistance
Bon roll.

[0013]  Metal alkoxide on carbon roll
Impregnated, hydrolyzed at a temperature of 200 ° C. or less,
Baking at a temperature of 0 ° C. or less, the surface of TiN or TiC
Wear-resistant car characterized by forming a wear-resistant coating
Manufacturing method of bon roll.

[0014]  TiN or TiC in base carbon
Metal alkoxide on a carbon roll with dispersed particles
And hydrolyzed at a temperature of 200 ° C. or less,
Abrasion resistance characterized by firing at a temperature of 00 ° C or less
Manufacturing method of carbon roll.

[0015]  1000 from impregnation of metal alkoxide
Perform firing up to ℃ below several timesSaid orWear resistance
Of producing a conductive carbon roll.

[0016]  Metal alkoxide is ZrO_Two ・ SiO
_Two Or 3Al_Two O_Three ・ 2SiO_Two GenerateSaid ~
The method for producing a wear-resistant carbon roll according to any one of the above.

[0017]

According to the present invention, in order to suppress the occurrence of temperature distribution in the roll due to the contact with the metal material and the ambient temperature, and to prevent the roll from expanding even if the temperature distribution occurs, the roll body length is reduced. Focusing on the material, a material that easily diffuses heat and does not expand thermally was studied. Materials with high thermal conductivity include copper and silver, and materials with low thermal expansion include non-conductive materials such as ceramic.Generally, materials with high thermal conductivity have large thermal expansion and conversely Difficult materials have the property of poor heat conduction. However, carbon is a unique material having both properties of good thermal conductivity and low thermal expansion. Extruded graphite also has the property of increasing the thermal conductivity as the crystallization proceeds. In particular, since the crystal is oriented in the extrusion direction, the heat conduction is particularly high in this direction, and shows a thermal conductivity that is two to three times that of the iron usually used. Therefore, if the extrusion direction is set to the roll body length direction, the heat is easily diffused in the body length direction, and the temperature distribution is hardly obtained even when contacting with a high-temperature metal. On the other hand, graphite has a small linear expansion coefficient and is 1/2 to 1/1 / of iron.
Since there is only an elongation of 10, the amount of thermal expansion is small even if the temperature distribution is provided, and the profile is unlikely to change. In many other carbon materials, those obtained by CIP molding and those molded by molding have similar properties.

As described above, carbon has an effective property for preventing thermal crown, but is soft on the other hand, and when used as a roll, there is a problem of abrasion resistance. Therefore, in order to impart abrasion resistance to the roll while making full use of the properties of carbon, TiN or Ti
C to form a wear-resistant coating, or TiN or Ti
The wear problem is avoided by dispersing the C particles into the base carbon.

TiN and TiC have extremely high hardness, and if these films are formed on the outermost layer of the carbon roll, the abrasion resistance of the roll itself becomes extremely high. The coating can be formed by spraying or CVD on the carbon roll surface,
A thickness of 150 to 200 μm is sufficient.

Both TiN and TiC not only have sufficient hardness but also have conductivity, and can be sufficiently used as a current-carrying roll. Comparing TiN and TiC, TiC is much harder and more resistant to oxidation than TiN, but TiN has better conductivity and conducts electricity like carbon.

When TiN or TiC particles are dispersed in the base carbon, the presence of these hard particles contributes to improving the wear resistance of the entire roll. In this case, TiN or T
The iC particles are commercially available, and a roll can be manufactured by mixing the mixture with carbon, extruding the mixture, and firing the mixture.
It is manufactured by mixing wt%. Thus, TiN or Ti
When the C particles are dispersed in the base carbon, the carbon is exposed on the roll surface. Since carbon has good adhesion to a steel plate, it can be said that carbon is particularly preferable for an energizing roll.

In the case of a transport roll or the like used at a low temperature, the oxidation resistance does not matter, but when used at a high temperature, oxidation of the carbon of the roll must be prevented. For this purpose, fine particles may be filled so as to close fine pores existing in the carbon, and the carbon particles may be protected from oxygen. This involves impregnating the fine pores of a carbon roll with a metal alkoxide, hydrolyzing it to form a metal hydroxide, and then oxidizing the metal hydroxide at a temperature of 1000 ° C. or lower to form a metal oxide. This is performed by obtaining a protective film for the object. That is, since many fine pores exist between carbon particles of the carbon roll, first, a vacuum treatment is performed to hold the carbon roll under a reduced pressure such as a pressure of 2 to 8 mmHg to remove air in the pores. A metal alkoxide impregnating agent is injected below to impregnate the pores with the metal alkoxide. Thereafter, when the carbon roll is heated to 200 ° C. or lower, the metal alkoxide reacts with the moisture in the impregnating agent to cause C ₂ H ₅ OMe + H ₂ O → C ₂
Is hydrolyzed as H ₅ OH + MeOH, metal hydroxide is generated. At this time, if the temperature of the hydrolysis exceeds 200 ° C., bumping of the solution occurs, and the impregnation amount is reduced. Then, it heats to the temperature of 1000 degreeC or less, and produces | generates a metal oxide from a metal hydroxide. As a result, the fine pores in the carbon can be filled with the metal oxide to prevent the invasion of oxygen, and the oxidation resistance effect can be obtained. It is preferable to perform this operation a plurality of times because the filling degree of the metal oxide is improved.

As the metal alkoxide, for example, Al
(OC ₂ H ₅ ) ₃ , Si (OC ₂ H ₅ ) ₄ , Zr (OC
₅ H ₁₁ ) ₄ , ZrSi (OC ₅ H ₁₁ ) ₄ or the like dispersed in an alcohol such as ethanol or isopropanol can be used. In particular, ZrO ₂ · Si as an oxide
When O ₂ and 3Al ₂ O ₃ .2SiO ₂ are generated, they have a coefficient of expansion substantially equal to the coefficient of expansion of carbon. Al (OC ₂ H ₅ ) ₃ and Si
When (OC ₂ H ₅ ) ₄ is oxidized, 3Al ₂ O ₃ .2
A mixture of SiO ₂ and a mixture of Si (OC
₂ H _{5) 4} and Zr (OC ₅ H _{11) 4} and a mixing ratio of a composition of ZrO ₂ · SiO ₂ when oxidized and it is preferred to impregnate the ZrSi (OC ₅ H _{11) 4} .

[0024]

The embodiments will be described below.

[0025]

Embodiment 1 FIG. 1 (a) shows a side section of the carbon roll of the present invention, and FIG. 1 (b) shows an AA section of FIG. 1 (a).

The carbon test material used for impregnation had a thermal conductivity of 140 [W / m ² , fired at 3000 ° C.
K] and an outer shape 230 having a linear expansion coefficient of 1 × 10 ⁻⁶ [1 / ° C.]
mm, a cylinder with a length of 1000 mm and a through-hole with an inner diameter of 150 mm for mounting a shaft. This carbon was degassed under reduced pressure of 2 to 8 mmHg for 60 minutes to remove air in the pores of the carbon, and then impregnated with alkoxide under reduced pressure for 30 minutes. Thereafter, the pressure was returned to the atmospheric pressure and the temperature was further maintained for 30 minutes. After being taken out of the impregnating agent and maintained at room temperature for 24 hours, hydrolysis treatment was performed at 150 ° C. for 24 hours. Thereafter, baking was performed in a lead hammer furnace at 900 ° C. for 20 hours, followed by heat treatment at a different heat treatment temperature for 15 days.

A shaft 3 made of 3000 iron was placed in the carbon sleeve 1 thus treated, and both ends of the sleeve 1 were fixed with fixing rings 2. The surface of the roll has a 150 μm T
Each of iC and TiN was plasma sprayed. Although not shown, four holes with a diameter of 10 mm and a depth of 30 mm are drilled at both ends of the carbon sleeve 1 at 90 ° intervals in the body length direction, and bolts are passed through the end face side of the fixing ring 2 through the sleeve 1.
The fixing ring 2 was fixed to the shaft 3 by passing a hexagonal bolt through a hole formed in the outer periphery. A 75 mm cold rolled steel sheet having a width of 500 mm and a thickness of 0.3 mm is placed on this roll.
The profile of the roll after heating at 0 ° C. and contacting for 1 hour was measured with a displacement meter that cooled the stylus. The same experiment was performed using an iron roll having the same size as the roll of the present invention. As a result, the difference between the center where the steel plate contacted and the steel plate edge was 10 μm, and the difference between the iron roll and the 500 μm
Approximately 1/5 as compared with the above, and the thermal crown could be greatly suppressed.

[0028]

Example 2 In order to confirm the wear resistance effect of the roll of the present invention, carbon rolls were manufactured as shown in Table 1 in the same manner as in Example 1, and a wear test by contact rotation was performed by a rotary contact type wear tester. Carried out. The material of the reference roll was mild steel assuming a steel plate. The test roll was brought into contact with the reference roll so that a rolling force of 5 kg / mm was applied to the roll contact portion, and the amount of wear after rotating at 500 rpm for 5 hours was measured. Table 1 shows the results of the wear test. Roll numbers A and B formed films by plasma spraying. Also,
Roll Nos. C and D were produced by mixing 30% by weight of each of carbon materials, TiC and TiN, performing a CIP treatment, and then firing at 2600 ° C.

[0029]

[Table 1]

As shown in Table 1, the roll A of the present invention,
B, C, and D had much less wear than the conventional rolls E and F.

[0031]

Example 3 Next, impregnation with various alkoxides was performed for 50 minutes.
A test piece was prepared by applying a carbon material having a size of 50 mm × 10 mm to an oxidation resistance test. The oxidation resistance test is
Dew point at 1050 ° C., N ₂ -25% H ₂ at + 40 ° C.
The test was repeated four times under the condition that the dew point was -40 ° C. and the dew point was 24 hours, and the test was performed for a total of 192 hours, and the oxidation loss after the test was evaluated by the weight loss rate. Table 2 shows the results of the oxidation resistance test.

[0032]

[Table 2]

Rolls 2 to 4 and 1 impregnated with colloidal particles
Nos. 2 to 14 showed only the same oxidation resistance as the untreated carbon rolls 1 and 11. Even rolls impregnated with metal alkoxide, rolls 8 to 1 exhibiting remarkably oxidation resistance
0, 18 to 20 and a roll 5 that does not show much oxidation resistance
-7, and 15-17. The rolls 8 to 10 and 18 to 20 exhibiting remarkable oxidation resistance were made of ZrSiO ₄ and 3Al ₂ O ₃ .3 at a test atmosphere temperature of 1050 ° C.
It was impregnated with a metal alkoxide having a SiO ₂ composition. On the other hand, rolls 5 that do not show much oxidation resistance
Nos. 7, 15 to 17 were impregnated with metal alkoxides having a composition of Al ₂ O ₃ , SiO ₂ and ZrO _{2 at} a test atmosphere temperature of 1050 ° C. The difference between these alkoxides is presumed to be due to the coefficient of thermal expansion determined by the chemical composition. That is, those exhibiting remarkable oxidation resistance have a thermal expansion coefficient of about 4 × 10 ⁻⁶ [ ^1/1 /
[° C.], whereas those which do not show much oxidation resistance are 8 × 10 ⁻⁶ [1 / ° C.], which is larger than carbon. This is probably due to peeling.

[0034]

The abrasion-resistant carbon roll of the present invention has a low temperature distribution even when it comes into contact with a high-temperature material to be heated, and has a small coefficient of thermal expansion, so that the generation of a thermal crown can be suppressed. Therefore, poor contact can be avoided, and deformation of the strip or the like heated to a high temperature and uneven temperature can be prevented. Therefore, for example, when used in a continuous annealing furnace for steel sheets, the roll profile is stable even if the sheet width is changed, so that the deterioration of the sheet shape can be prevented, and the occurrence of meandering can be prevented. Therefore, production can be performed without reducing the line speed, and high-speed conveyance can be performed.
Further, when used for roll cooling, carbon can be cooled efficiently and without shape defects due to good heat conduction of carbon. Even when applied to a current-carrying roll, the profile is stable even when it comes into contact with a metal heated to a high temperature, so that it is possible to prevent the occurrence of sparks due to poor contact.

Regarding wear, which was a disadvantage of carbon,
This roll has a hard coating on the surface layer or hard particles are dispersed in the base material, so that it can be used stably for a long time. Further, in the case of a coating film, even if the abrasion progresses, the base material can be used any number of times by reprocessing only the surface layer, which is economical. Further, even in the case where oxidation resistance is required for use in a high-temperature atmosphere, filling the fine pores of carbon with a metal oxide can sufficiently cope with it. Since carbon is lightweight, it also has the advantage that no auxiliary power is required for the roll.

[Brief description of the drawings]

FIG. 1 is a view showing a cross-sectional structure of a carbon roll of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Carbon sleeve 2 Fixing ring 3 Shaft 4 Coating

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ Identification code FI C21D 1/40 C21D 9/56 101G 9/56 101 C04B 35/52 B 35/54 B (58) Fields surveyed (Int.Cl. . ^7, DB name) C21D 1/00 115 C21D 1/40 C21D 9/56 101 B21B 27/00 B21B 39/00 C04B 35/52 C04B 41/85

Claims (7)

(57) [Claims] 1. A wear-resistant carbon roll in which particles of TiN or TiC are dispersed in base carbon. 2. The wear-resistant carbon roll according to claim 1, wherein the fine pores of the base carbon are filled with a metal oxide. Wherein the metal oxide is ZrO ₂ · SiO ₂ or 3Al ₂ O ₃ · 2SiO ₂ in which claim 2 abrasion carbon roll according. 4. A carbon roll impregnated with a metal alkoxide, hydrolyzed at a temperature of 200 ° C. or less,
A method for producing a wear-resistant carbon roll, wherein the method comprises sintering at a temperature of not more than ° C to form a wear-resistant coating of TiN or TiC on the surface. 5. A carbon roll in which particles of TiN or TiC are dispersed in base metal carbon is impregnated with a metal alkoxide, and is hydrolyzed at a temperature of 200 ° C. or less.
A method for producing an abrasion-resistant carbon roll, characterized by firing at a temperature of 0 ° C. or lower. 6. 1000 ° C. from the impregnation of the metal alkoxide
The method for producing a wear-resistant carbon roll according to claim 4 or 5, wherein the following firing is performed a plurality of times. 7. The method according to claim 1, wherein the metal alkoxide is ZrO ₂ .SiO ₂
Or 3Al ₂ O ₃ · 2SiO ₂ generates the claims 4 to
7. The method for producing a wear-resistant carbon roll according to any one of 6 .