Roller With Coating

Abstract

A heatable roller suitable for a machine for producing and/or upgrading a web of material, in particular a fibrous material web such as a paper, paperboard or tissue web. The roller has a main element with a metallic and cylindrical roller wall which is heatable by suitable means and on the radially outer side of which there is, at least in sections, a coating. When the roller is used as intended, the coating provides a web contact side which can be brought into contact with the web of material. The coating includes, or is formed by, at least one metallic or metal-carbidic layer with a first layer component providing a matrix and a second layer component distributed in the matrix. The first layer component has a higher abrasion resistance than the second layer component and the second layer component has a greater thermal conductivity than the first layer component.

Claims

1-18. (canceled)

19. A heatable roller for a machine for processing a web of material, the roller comprising: a main element having a heatable, metallic, cylindrical roller wall; a coating formed on a radially outer side of said roller wall, at least in sections thereof, for providing a web contact surface to be brought into contact with the web of material; said coating including, or consisting of, at least one metallic or metal-carbidic layer, said at least one metallic or metal-carbidic layer including, or consisting of, a first layer component providing a matrix and a second layer component distributed in said matrix; and said first layer component having a higher abrasion resistance than said second layer component and said second layer component having a greater thermal conductivity than said first layer component.

20. The heatable roller according to claim 19, wherein said second layer component is formed, in essence, of a plurality of discrete regions.

21. The heatable roller according to claim 19, wherein said first layer component comprises, of consists of, an iron-based alloy and/or a cermet.

22. The heatable roller according to claim 21, wherein said iron-based alloy comprises iron and at least one further constituent selected from the group consisting of chromium, niobium, tantalum, molybdenum, silicon, boron and tungsten.

23. The heatable roller according to claim 19, wherein said second layer component comprises, or consists of, copper or a copper-based alloy.

24. The heatable roller according to claim 23, wherein said at least one layer is formed with 60% by weight or more of said first layer component and with not more than 40% by weight of said second layer component.

25. The heatable roller according to claim 20, wherein discrete regions of said second layer component have a size in a range from 5 to 50 m.

26. The heatable roller according to claim 19, wherein said second layer component is configured to at least partly form a 3-dimensional network.

27. The heatable roller according to claims 26, wherein a plurality of discrete regions of the second layer component are in contact with one another to form the 3-dimensional network.

28. The heatable roller according to claim 19, wherein said coating is formed by a single one of said at least one metallic or metal-carbidic layer.

29. The heatable roller according to claim 19, wherein said at least one layer has a specific thermal conductivity in a range from 15 W/mK to 250 W/mK.

30. The heatable roller according to claim 19, wherein said at least one layer has an abrasion resistance of less than 0.6 g measured in accordance with ASTM G65-04.

31. The heatable roller according to claim 19, wherein said coating has a thickness in a range from 50 pm to 1500 m.

32. A coating for a component of a machine for processing a web of material, the coating comprising: at least one metallic or metal-carbidic layer including, or consisting of, a first layer component providing a matrix and a second layer component distributed in said matrix; and said first layer component having an abrasion resistance greater than an abrasion resistance of said second layer component; and said second layer component having a thermal conductivity greater than a thermal conductivity of said first layer component.

33. The coating according to claim 32 consisting of said at least one metallic or metal-carbidic layer.

34. A process for coating a heatable roller having a roller body with a metallic and cylindrical roller wall that is heatable by a heating device, the process comprising: providing the roller a with a radially outer side; and applying a coating to the outer side, the coating including, or consisting of, a least one metallic or metal-carbidic layer, thereby applying the at least one metallic or metal-carbidic layer with a first layer component providing a matrix and a second layer component distributed in the matrix, the first layer component having a higher abrasion resistance than the second layer component and the second layer component having a greater thermal conductivity than the first layer component.

35. The process for coating a heatable roller according to claim 34, which comprises surface-treating the radially outer side of the roller wall prior to applying the coating.

36. The process for coating a heatable roller according to claim 35, wherein the surface-treating step comprises grinding a radially outer surface of the roller wall.

37. The process for coating a heatable roller according to claim 34, which comprises producing the at least one layer by thermal spraying.

38. The process for coating a heatable roller according to claim 37, which comprises grinding the metallic or metal-carbidic layer providing the web contact side after the thermal spraying.

Description

[0033] The invention is illustrated below with the aid of a working example, see table 1 and FIG. 1 and also FIGS. 2 and 3.

[0034] The present working example is a coating which is formed by only one metallic layer and has been applied to the radially outer side of the cylindrical surface of a Yankee drying cylinder and has the following properties and the following composition:

TABLE-US-00001 TABLE 1 Competition sample 1 Competition (competition sample 2 Invention HVOF) (competition arc) Com- Iron-based alloy: Fe balance, Fe balance, position: Fe > 70% by weight, Mn 2% by weight, Mn 1.65% by Cr 20.6% by weight, Cr 14% by weight, weight, Nb 4.5% by weight, Mo 24% by weight, Cr 29% by Ta 3.5% by weight W 10% by weight, weight, Pure copper (99.9% C 5% by weight B 3.75% by by weight of Cu) weight, Ratio of iron-based Si 1.6% by alloy to copper in weight, the layer: 85% by weight to 15% by weight Thermal 32 W/mK 9 W/mK 11 W/mK conductivity Abrasion 0.17 g 0.2 0.2 resistance ASTM G65-04

[0035] It can be seen that the solution according to the invention provides a significantly higher thermal conductivity than is known from the prior art, at a comparable abrasion resistance.

[0036] FIG. 1 shows a section, which is not to scale, of a roller wall 1 of a Yankee drying cylinder having the coating 2 according to the invention as per table 1. The coating 2 is formed by a metallic layer which in turn is formed by a first layer component 3 providing a matrix and a second layer component 4 (shown hatched) distributed in the matrix 3.

[0037] In the present case, the second layer component 4 is pure copper (99.9% by weight) and in its entirety formed by a plurality of discrete regions which at least partly adjoin one another. The discrete regions of the second layer component 4 have a size in the range from 5 to 50 m. Furthermore, the second layer component 4 at least partly forms a 3-dimensional network, with a majority of the discrete regions of the second layer component 4 being in contact at the boundaries to form the 3-dimensional network.

[0038] The layer 2 and thus the coating has a specific thermal conductivity in the region of 32 W/mK and an abrasion resistance in the region of 0.2 g measured in accordance with ASTM G65-04. The thickness of the coating 2 is 500 m.