DE102011006295A1 - Preparing a coated metal construction part on iron basis comprises forming a burnishing layer on a part of the metal construction partial surface in a burnishing method and applying a layer made of a sliding material on the burnishing layer - Google Patents

Abstract

Preparing a coated metal construction part (1) on iron basis comprises forming a burnishing layer (4) at least on a part of the metal construction partial surface in a burnishing method. A layer (5) made of a bearing material is applied on the burnishing layer in a gaseous phase separation method. An independent claim is also included for a metal construction part, preferably prepared by the above method, comprising a burnishing layer at least on a part of metal construction partial surface formed in a burnishing method.

Description

Field of the invention

The invention relates to a method for producing a coated iron-based metal component, in which a burnishing layer is formed at least on a part of the metal component surface in a burnishing method.

Background of the invention

Metal components with a burnishing layer applied by a burnishing process are used in many technical applications. An example is the field of storage technology, especially the area of rolling bearings. The burnishing layer is formed by means of a burnishing method in which the workpiece to be burned is immersed one or more times in acidic or alkaline solutions or molten salts. An oxide layer of FeO or Fe ₂ O ₃ or a mixed oxide layer (conversion layer) of these two oxides is formed on the surface. The burnishing layer is usually deep black and especially resistant to alkaline media.

Since burnishing layers are distinguished by very smooth surfaces with little roughness, they are frequently used, in particular in the field of bearing technology, to improve the running-in properties and, in particular, to increase the service life for components which are in tribological contact and highly stressed. However, the wear resistance of the burnishing layers is relatively low, that is, they wear relatively quickly in tribologically loaded workpieces, which is why it is necessary to ensure a continuous lubrication. However, this is not possible in some applications, problems also arise in the case of a lubricant deficit.

Summary of the invention

The invention is therefore based on the problem to provide a method for producing a burnishing layer having a metal component, in which the wear resistance of the burnishing layer is improved to solve this problem is provided according to the invention in a method of the type mentioned that the burnishing layer in a Gasphasenabscheideverfahren a Layer is applied from a sliding material.

The method according to the invention is characterized in that an additional sliding layer, which is deposited from the gas phase, is applied to the burnishing layer. This is possible since, as stated, the burnishing layer has an extremely low roughness and, as a result, is outstandingly suitable as a substrate for a vapor-deposited sliding layer which adheres very well to the burnishing layer surface. By means of this sliding layer can be a significant improvement in the wear resistance of the burnishing layer and thus improve the resistance of the same due to a reduction in the coefficient of friction can be achieved. This results in an extension of the life of the applied functional surface, namely the burnishing layer, on which therefore ultimately the lubricant is deposited "directly". An extension of the service life by more than ten times as compared to burnishing layers not covered by the sliding material layer is readily achievable.

Due to the manufacturing method according to the invention of the metal components, the range of application of these metal components, especially in the storage area, can be significantly extended, for example, small bearings with an inner diameter <75 mm, the process technically allow no or only very expensive rework in the area of the burnishing or due to the very low Storage tolerances require a very thin and dimensionally stable coating. Another area of application relates to very large, thin-walled and distortion-prone and stress-prone bearings, such as bearings for computed tomography, as well as bearings that run only under minor or deficient lubrication, such as bearings used in vacuum technology. Another field of application is the mechatronic components as well as linearly moving components such as control pistons and the like. The list is not exhaustive, but merely exemplary.

In the field of rolling bearing technology, a metal component may for example be a rolling element itself or else the raceway of an inner or outer ring or the like.

The gaseous phase deposited slip layer may be of any nature as long as it has the desired lubricating or lubricating properties. For example, as sliding materials MoS ₂ , WC, NbC, SbC, TaC or BiC be mentioned, which are all materials that form the tribomechanical properties improving and extending the life surfaces. The layer thickness of the applied layer should be between 50-500 nm, in particular between 100-400 nm. It is to be chosen so that the desired surface property is given.

The gas phase deposition process may be a PVD, PACVD or CVD process, the process used being optionally selected depending on the slip material to be deposited.

The burnishing layer itself should have an average roughness Ra ≦ 0.1 μm, in particular Ra ≦ 0.05 μm. Although the burnishing layer forms a very smooth, even surface, it can in individual cases, if appropriate even in a flat surface, but it may be necessary in individual cases, possibly also depending on the sliding material to be deposited, to reduce the burnishing roughness as part of a polishing process ,

A reworking of the deposited Gleitwerkstoffschicht is usually not required, because even after serving as a substrate burnishing layer is extremely smooth, and the deposited thereon Gleitwerkstoffschicht is very smooth. If necessary, it is possible to lubricate the sliding material layer in addition.

In addition to the process itself, the invention further relates to a metal component, which is produced in particular by the described method. The metal component is characterized by a burnishing layer formed in a burnishing process on at least part of the metal component surface, on which layer of a sliding material produced in a vapor deposition process is additionally applied.

The metal component can be any component, but primarily it concerns rolling bearing and / or sliding bearing components, for example inner and / or outer rings, rolling elements or cages for rolling elements and the like.

The applied sliding material layer can be MoS ₂ , WC, NbC, SbC, TaC or BiC, it should have a thickness between 50-500 nm, in particular between 100-400 nm.

Overall, the invention allows the production of metal components which are in many respects advantageous. On the one hand, the dimensions of the metal component remain virtually unchanged due to the functional layer, which only has a thickness of approximately 1500-2000 nm, consisting of the burnishing layer and the sliding material layer, which is advantageous in particular in the field of bearing technology. Also, the functional layer shows a very low surface roughness, as well as the tribological properties significantly improved thereby and the mechanical strength and wear resistance can be significantly increased. A rework of the functional layer is not required. Further, due to the excellent tribological properties, lower cost and lower viscosity lubricants having less internal friction may be used, as well as any lubricant change intervals may be extended. It is also possible to use the metal components, for example in the form of rolling bearings, under dry friction or insufficient lubrication. Another advantageous criterion of the functional layer applied according to the invention is its significantly higher thermal stability compared to other layers. Because as a result of the deposition from the gas phase, the layers applied according to the invention, for example, the MoS ₂ layer, stable up to about 600 ° C, resulting in an even larger application.

Detailed description of the drawing

In the figure is a schematic diagram of a metal component according to the invention 1 shown. In the metal component 1 For example, it is the inner ring of a rolling bearing, of course, the description of the layer structure and the production of the metal component 1 Of course, the layer of course for a wide variety of metal components (from the rolling bearing area, for example, the outer ring or the rolling elements or the Wälzkörperkäfig be mentioned) applies.

The metal component 1 on the one hand, the component body 2 based on an iron-based steel, for example 16MnCr5, C45, 100Cr6, 31CrMoV9 or 80Cr2, this list being of course merely exemplary in nature and in no way conclusive.

On the outside of the component body 2 is a functional layer 3 formed, consisting of a burnishing layer 4 directly on the component body 2 is applied, and one on the burnishing layer 4 applied sliding material layer 5 ,

The burnishing layer 4 is applied in a burnishing process. For this purpose, a two-bath method is preferably used.

For burnishing the component body 2 first, the component body 2 degreased, preferably by an alkaline hot degreasing, after which it is rinsed with water and pickled by means of a Mischbeize with inhibitor. After a new rinse, the component body 2 in the first burnishing bath given. The bronzing bath is made from a brining salt consisting of NaOH and NaNO ₂ and water. The content of NaOH is about 10-30%, the content of NaNO ₂ is about 70-90%. The bath itself is used in a ratio of brining salt: water = 1: 1. The bath temperature is 135-140 ° C. The residence time in the bath is preferably about 10-20 minutes. The duration of treatment is ultimately dependent on the composition, concentration and temperature of the bath and the nature and condition of the component body. The bath itself is continuously kept constant by adding water and / or brining salt.

After completion of the first Brünierschritts the component body 2 rinsed, followed by the second Brünierbad followed. The bath composition corresponds to that of the first Brünier bath, the residence time is the same. Only the bath temperature is slightly higher than at the first Brünierbad, here the bath temperature is 140-145 ° C. The temperature should be between 5-10 ° higher than the first burnishing bath.

After the second burnishing bath, the component body becomes 2 one or more times preferably rinsed with water, after which it receives a corrosion protection coating of ethanolamine (5% in warm water). This ethanolamine serves to protect against corrosion of the burnishing layer, which is subsequently dried in a circulating air dryer at elevated temperature.

The finished coated component body 2 Now wear the burnishing layer 4 , which is usually a mixed oxide (conversion) layer of FeO and Fe ₂ O ₃ .

This is now the Gleitstoffschicht 5 applied. For this purpose, the burnished component body 2 placed in the coating chamber of a gas phase separation plant. Primarily, a PVD or a PACVD method is used for this purpose. In the PVD process, the material to be deposited is evaporated, which can be done, for example, thermally or by electron beam. Sputtering is also possible for transferring the material to be applied into the gas phase. In the PACVD process, which is a special form of chemical vapor deposition because of plasma, the material to be deposited is transferred to the gas phase via the plasma. Regardless of the method used, the sliding material is deposited on the surface of the burnishing layer 4 as a sliding material layer 5 from. The Brünierschichtoberfläche is advantageous very smooth and planar, it has a roughness of Ra ≤ 0.05 .mu.m.

The thickness of the functional layer 3 total is about 1500-2000 nm, wherein the sliding material layer 5 should have a thickness between 100-400 nm. The thickness is chosen so that the desired surface properties are set.

As a sliding material MoS ₂ is preferably used, but other sliding materials such as WC, Nb or TaC and the like can be deposited.

LIST OF REFERENCE NUMBERS

1

metal component

2

component body

3

functional layer

4

Brünierschicht

5

Gleitwerkstoffschicht

Claims (10)

A method for producing a coated iron-based metal component, wherein a burnishing layer is formed at least on a part of the metal component surface in a burnishing method, characterized in that a layer of a sliding material is applied to the burnishing layer in a vapor deposition method. A method according to claim 1, characterized in that a layer of MoS2, WC, NbC, SbC, TaC or BiC is applied as the layer. A method according to claim 1 or 2, characterized in that the thickness of the layer is 50-500 nm, in particular 100-400 nm. Method according to one of the preceding claims, characterized in that the layer is applied in a PVD, PACVD or CVD method. Method according to one of the preceding claims, characterized in that the burnishing layer has an average roughness Ra ≤ 0.1 μm, in particular Ra ≤ 0.05 μm. Metal component, in particular produced by the method according to one of the preceding claims, having a burnishing layer (at least on a part of the metal component surface in a burnishing method) (US Pat. 4 ), characterized in that on the burnishing layer ( 4 ) a layer produced in a gas phase deposition process ( 5 ) is applied from a sliding material. Metal component according to claim 6, characterized in that the layer ( 5 ) from MoS ₂ , WC, NbC, SbC, TaC or BiC. Metal component according to claim 6 or 7, characterized in that the thickness of the layer ( 5 ) Is 50-500 nm, in particular 100-400 nm. Metal component according to one of claims 6 to 8, characterized in that the total thickness of burnishing layer and Gleitwerkstoffschicht 1500-2000 nm. Metal component according to one of claims 6 to 9, characterized in that it is a rolling or sliding bearing component.

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