Roller for a roller furnace having at least one coating on the surface

Abstract

A roller for a roller furnace with a roller base body and a coating on the surface, wherein the coating has a first layer, containing: 10.0-30.0 wt.-% Si, 10.0-30.0 wt.-% Al(OH).sub.3, 1.0-3.0 wt.-% B.sub.4C, 0.5-1.5 wt.-% Y.sub.2O.sub.3, 0.1-1.0 wt.-% Fe.sub.2O.sub.3 and the remainder Al.sub.2O.sub.3 and a second layer, containing 10.0-30.0 wt.-% Si, 10.0-30.0 wt.-% Al(OH).sub.3, 1.0-3.0 wt.-% B.sub.4C, 2.0-4.0 wt.-% Y.sub.2O.sub.3 and the remainder Al.sub.2O.sub.3.

Claims

1. A roller for a roller furnace with a roller base body and a coating on the surface, wherein the coating has at least one layer, containing: 10.0-30.0 wt.-% Si 10.0-30.0 wt.-% Al(OH).sub.3 1.0-3.0 wt.-% B.sub.4C 0.5-1.5 wt.-% Y.sub.2O.sub.3 0.1-1.0 wt.-% Fe.sub.2O.sub.3 and the remainder Al.sub.2O.sub.3.

2. The roller for a roller furnace according to claim 1, wherein the coating has at least one layer, containing: 15.0-25.0 wt.-% Si 15.0-25.0 wt.-% Al(OH).sub.3 1.5-2.5 wt.-% B.sub.4C 0.8-1.2 wt.-% Y.sub.2O.sub.3 0.3-0.7 wt.-% Fe.sub.2O.sub.3 and the remainder Al.sub.2O.sub.3.

3. The roller for a roller furnace according to claim 1, wherein the roller has a diameter of 60 mm to 80 mm.

4. The roller for a roller furnace according to claim 1, wherein the wall of the roller has a thickness of 6 mm to 12 mm.

5. The roller for a roller furnace according to claim 1, wherein the roller has a length of 2500 mm to 4000 mm.

6. The roller for a roller furnace according to claim 1, wherein the roller has a taper on both ends over a length of 80 mm to 100 mm.

7. The roller for a roller furnace according to claim 1, wherein the coating has at least, a) a first layer, containing: 10.0-30.0 wt.-% Si 10.0-30.0wt.-% Al(OH).sub.3 1.0-3.0 wt.-% B.sub.4C 0.5-1.5 wt.-% Y.sub.2O.sub.3 0.1-1.0 wt.-% Fe.sub.2O.sub.3 and the remainder Al.sub.2O.sub.3 and b) a second layer, containing: 10.0-30.0 wt.-% Si 10.0-30.0 wt.-% Al(OH).sub.3 1.0-3.0 wt.-% B.sub.4C 2.0-4.0 wt.-% Y.sub.2O.sub.3 and the remainder Al.sub.2O.sub.3.

8. The roller for a roller furnace according to claim 7, wherein, a) the first layer, contains: 15.0-25.0 wt.-% Si 15.0-25.0 wt.-% Al(OH).sub.3 1.5-2.5 wt.-% B.sub.4C 0.8-1.2 wt.-% Y.sub.2O.sub.3 0.3-0.7 wt.-% Fe.sub.2O.sub.3 and the remainder Al.sub.2O.sub.3 and b) the second layer, contains: 15.0-25.0 wt.-% Si 15.0-25.0 wt.-% Al(OH)3 1.5-2.5 wt.-% B.sub.4C 2.8-3.2 wt.-% Y.sub.2O.sub.3 and the remainder Al.sub.2O.sub.3.

9. The roller for a roller furnace according to claim 7, wherein the proportion of Al.sub.2O.sub.3 in the first layer is 40.0-70.0 wt.-%, and the proportion of Al.sub.2O.sub.3 in the second layer is 40.0-70.0 wt.-%.

10. The roller for a roller furnace according to claim 9, wherein the proportion of Al.sub.2O.sub.3 in the first layer is 50.0-60.0 wt.-% and the proportion of Al.sub.2O.sub.3 in the second layer is 50.0-60.0 wt.-%.

11. The roller for a roller furnace according to claim 7, wherein the first layer has a thickness of 0.2 mm to 1.0 mm.

12. The roller for a roller furnace according to claim 7, wherein the second layer has a thickness of 0.1 mm to 0.5 mm.

13. A method for producing a roller for a roller furnace with at least one layer according to claim 1, comprising: a) coating a roller with a first aqueous suspension, b) drying the coated roller at 90 C. to 120 C. for 0.5 to 2 hours, and c) sintering the dried roller at 1400 C. to 1500 C. for 6 to 8 hours in an N.sub.2 atmosphere.

14. The method for producing a roller for a roller furnace according to claim 13, wherein the roller sintered in an N.sub.2 atmosphere is coated and the coated roller is sintered, or the roller is coated and the coated roller is sintered.

15. A method for producing a roller for a roller furnace with at least one layer according to claim 1, comprising: a) coating a roller with a first aqueous suspension, b) drying the coated roller at 90 C. to 120 C. for 0.5 to 2 hours, c) coating the dried roller with a second aqueous suspension, d) drying the coated roller at 90 C. to 120 C. for 0.5 to 2 hours, and e) sintering the dried roller at 1400 C. to 1500 C. for 6 to 8 hours in an N.sub.2 atmosphere.

16. A method comprising hot forming metal parts with a roller for a roller furnace according to claim 1.

17. The method according to claim 16, wherein the hot forming metal parts are AlSi coated metal sheets.

Description

EXAMPLE 1

(1) Base body coated only with a base layer

(2) NSiC base body N-Durance was coated with an aqueous suspension of AnnaPlast 171-5 (Table 4)

(3) then dried at 110 C. for 1 hour and

(4) then sintered at 1470 C. for 7 hours in an N.sub.2 atmosphere. More detailed data are found in Table 1.

EXAMPLE 2

(5) Base body coated with a base layer and a cover layer

(6) NSiC base body N-Durance was coated with an aqueous suspension of AnnaPlast 171-5 (Table 4),

(7) then dried at 110 C. for 1 hour,

(8) then coated with an aqueous suspension of AnnaPlast 171-3 (Table 4), and

(9) then dried at 110 C. for 1 hour, and

(10) then sintered at 1470 C. for 7 hours in an N.sub.2 atmosphere. More detailed data are found in Table 1.

(11) TABLE-US-00001 TABLE 1 Example 1 and Example 2 Invention Example 1 Example 2 Components Base body Fired, Fired, containing: containing: Base body N-Durance N-Durance contains: Single coated Double coated Layer 1 contains: cf. Apl 171-5 Apl 171-5 Layer 2 contains: No 2nd layer Apl 171-3 Firing 1470 C. - 1470 C. - N.sub.2 atmosphere N.sub.2 atmosphere Field test Temperaturee 900 C. 900 C. with rollers Time <4000 h <4000 h Result no infiltration no infiltration or reaction with or reaction with the roller the roller structure, slight, structure, very uniform, readily slight, uniform, removable caking readily removable caking Corrosion Temperature 900 C. 900 C. test Time 90 h 90 h Result no infiltration no infiltration no caking no caking

EXAMPLE 3

(12) Green base body coated with a base layer, wherein the layer was free of silicon oxide.

(13) NSiC base body N-Durance was coated with an aqueous suspension of AnnaPlast 171-5 (Table 4)

(14) then dried at 110 C. for 1 hour and

(15) then sintered at 1470 C. for 7 hours in an N.sub.2 atmosphere. More detailed data are found in Table 2.

EXAMPLE 4

(16) Green base body coated with a base layer and a cover layer, wherein both layers were free of silicon oxide.

(17) NSiC base body N-Durance was coated with an aqueous suspension of (AnnaPlast 171-5 (Table 4),

(18) then dried at 110 C. for 1 hour,

(19) then coated with an aqueous suspension of AnnaPlast 171-3 (Table 4), and

(20) then dried at 110 C. for 1 hour, and

(21) then sintered at 1470 C. for 7 hours in an N.sub.2 atmosphere. More detailed data are found in Table 2.

(22) TABLE-US-00002 TABLE 2 Example 3 and Example 4 Invention Example 3 Example 4 Components Base body Unfired, Unfired, containing: containing: Base body N-Durance N-Durance contains: Single coated Double coated Layer 1 contains: Apl 171-5 Apl 171-5 Layer 2 contains: No 2nd layer Apl 171-3 Firing 1470 C. - 1470 C. - N.sub.2 atmosphere N.sub.2 atmosphere Field test Temperature 900 C. 900 C. with rollers Time <4000 h <4000 h Result no infiltration no infiltration or reaction with or reaction with the roller the roller structure slight, structure very uniform, readily slight, uniform, removable caking readily removable caking Corrosion Temperature 900 C. 900 C. test Time 90 h 90 h Result no infiltration no infiltration no caking no caking

COMPARATIVE EXAMPLES 1 AND 2 (PRIOR ART)

(23) For this, two base bodies NSiC base bodies N-Durance were single coated with a coating containing Al.sub.2O.sub.3 and SiO.sub.2,

(24) then dried at 110 C. for 1 hour, and

(25) then sintered at 1250 C. for 7 hours in an O.sub.2 atmosphere. More detailed data are found in Table 3.

(26) TABLE-US-00003 TABLE 3 Comparative Example 1 and Comparative Example 2 Comparative Comparative Prior Art Example 1 Example 2 Components Base body Fired, Fired, containing: containing: Base body Mullite rollers N-Durance contains: mullite, corundum Single coated Single coated Layer 1 contains: From the group From the group Al.sub.2O.sub.3/SiO.sub.2 Al.sub.2O.sub.3/SiO.sub.2 Layer 2 contains: No 2nd layer No 2nd layer Firing <1250 C. - <1250 C. - O.sub.2 atmosphere O.sub.2 atmosphere Field test Temperature 900 C. 900 C. with rollers Time <4000 h <4000 h Result Firm, nonuniform Removal of the adhesion of AlSi coating material, on the roller adhesion of AlSi, surface, AlSi Firm, nonuniform diffuses into adhesion of AlSi the porous on the roller roller structure, surface. chemical reactions result in roller breakage. Corrosion Temperature 900 C. 900 C. test Time 90 h 90 h Result Infiltration Infiltration Caking Caking

(27) As seen in Tables 1 to 3, rollers according to the invention have greater durability than already known rollers. Known rollers from the Comparative Examples have the disadvantages of these rollers, namely infiltration and caking, which results in removal of the coating material and also in roller breakage. The result was unexpected and surprising.

(28) The following Table 4 presents the ingredients of the aqueous suspensions for producing the layers.

(29) TABLE-US-00004 TABLE 4 Layer 1 Apl 171-5 Base Layer Layer 2 Apl 171-3 Cover Layer % % 19.704 Si 19.417 Si 19.704 Al(OH).sub.3 19.417 Al(OH).sub.3 57.143 Al.sub.2O.sub.3 56.311 Al.sub.2O.sub.3 1.970 B.sub.4C 1.942 B.sub.4C 0.494 Fe.sub.2O.sub.3 0.000 Fe.sub.2O.sub.3 0.985 Y.sub.2O.sub.3 2.913 Y.sub.2O.sub.3 100.000 Total 100.000 Total

(30) The drawing comprises FIG. 1.

(31) FIG. 1 depicts the side view of a roller for a roller furnace having a coating on the surface. The coated roller 1 comprises a base body 2 and a coating on the outer surface of the base body of the roller 1. The roller 1 is a hollow roller with a cavity 3. The roller 1 has a taper 4 on both ends for attaching the drive sleeve. The roller 1 includes as material N-Durance. The roller 1 has, by way of example, a diameter of 60 mm and a length of 3070 mm. On both ends, the roller 1 is tapered over a length of 80 mm to a diameter of 59 mm. The roller includes, according to the invention, a coating with at least one or at least two layers on the outer surface.

LIST OF REFERENCE CHARACTERS

(32) 1 roller 2 roller base body 3 cavity of the roller 4 taper at the ends of the roller