DE102021200891A1 - Process for producing a wear-resistant oxide layer, component - Google Patents

Abstract

The invention relates to a method for producing a wear-resistant oxide layer (1) on an at least essentially flat surface (3) of a component (2), in particular an aluminum component, the surface (3), in particular an aluminum surface, being coated with an oxide layer (1) by means of laser alloying. is provided, and wherein a laser beam (4) is moved linearly over the surface (3) of the component (2) for the laser alloying. A lubricant pocket (8) is introduced into the surface (3) in at least one line section and is processed by the laser beam (4).

Description

The invention relates to a method for producing a wear-resistant oxide layer on an at least essentially flat surface of a component, in particular an aluminum component, the surface being provided with an oxide layer, in particular aluminum oxide layer, by means of laser alloying, and a laser beam being drawn linearly over the surface for the laser alloying is moved.

The invention also relates to a component, in particular a cylinder for a brake booster or plain or friction bearing, for a motor vehicle which has a wear-resistant oxide layer produced by laser alloying on at least one surface, in particular the running surface of the cylinder.

State of the art

Methods and components of the type mentioned are already known from the prior art. The selective or local production of an aluminum oxide layer by laser-induced oxidation as a result of the laser alloying of aluminum surfaces in particular is known, for example in the published patent application EP 2 853 616 B1 described. Pure aluminum oxide is significantly harder than aluminum and is therefore an excellent material for plain bearings. Laser alloying allows for improved protection against wear, with costly masking of the surface of the component to be treated being no longer necessary for production.

Disclosure of Invention

The method according to the invention with the features of claim 1 has the advantage that the lubricating or sliding properties of the treated surface are improved, so that friction and wear phenomena are reduced in continuous operation. According to the invention, a lubricant pocket is introduced into the surface in at least one line section, in particular along at least one line section, and processed by the laser beam. The lubricant pocket can be produced by the laser beam, ie by processing the surface, or a lubricant pocket can be introduced mechanically into the surface and then treated by the laser beam, ie also processed. In any case, there is a linear indentation in the form of the lubricant pocket in the surface, in which lubricant or lubricant can be absorbed during operation and released to the friction partners, such as the cylinder and a piston that can be displaced axially in the cylinder, during operation .

According to a preferred embodiment of the invention, at least one lubricant pocket is formed in the surface of the component by a simple change in the laser alloying, in which lubricant or lubricant can be stored or temporarily stored in order to use lubricant with a sliding or friction partner interacting on the surface during operation of the component or to be able to deliver lubricant and to permanently ensure hydrodynamic lubrication between the contact partners. This reduces friction losses and wear. For this purpose, it is provided that the laser beam, which is generated in particular by a disk laser (disk laser beam), is moved linearly in at least one line section of the linear movement at a predetermined angle inclined to the surface and/or is generated by an ultra-short pulse laser in order to create a Train lubricant pocket in the surface. While previously the laser beam was aligned at an angle or angle of incidence of 90° to the surface for surface treatment by laser alloying and then moved linearly over the surface, it is now provided that in at least one line section the laser beam is not perpendicular to the surface but inclined to it is aligned. This results in a uniform layer structure in this line section during the laser treatment, which leads to an asymmetrical contour—seen in cross section—with a depression introduced into the surface and an elevation adjoining it. A kind of wave is created in the surface, which creates the lubricant pocket in the depression. Preferably, several such line sections are generated on the surface with an inclined laser beam. It is assumed that the effective radius of the laser beam or the width of the laser beam is smaller, in particular much smaller than the surface of the component to be treated, so that the laser beam has to be moved linearly over the surface several times in order to form a continuous oxide layer on the component .

According to a preferred development of the invention, the laser beam is moved in the line section at an angle of 35° to 70°, in particular 45° to 65°, inclined to the surface of the component. This creates a particularly advantageous lubricant pocket, which ensures that the lubricant is received and released.

The laser alloying is particularly preferably carried out in an atmosphere with an oxygen content of at least 80%, in particular more than 85%. This creates an advantageous aluminum oxide layer or oxide layer on the surface of the treated component. This leads to an exothermic reaction between the component, in particular the aluminum component, and the oxygen, as a result of which the oxide layer, in particular aluminum oxide, is formed. As described above, the advantageous angle of the laser beam inclined to the surface creates the lubricant pocket in the aluminum oxide layer. In particular, a kind of wave form is created in the surface of the component, because the laser treatment results in both an elevation and a depression in the surface.

The laser beam is preferably moved linearly over the entire surface that is to be provided with the oxide layer, in particular over the entire surface of the component assigned to a sliding or friction contact partner, at the angle inclined to the surface. As a result, a large number of lubricant pockets are formed in the oxide layer, which improves the friction and wear properties of the component.

The laser beam is preferably moved linearly in at least one line section at an angle perpendicular or almost perpendicular to the surface. This results in a mixed treatment of the surface, namely on the one hand by the obliquely inclined laser beam and on the other hand by a laser beam aligned at least essentially perpendicularly to the surface. This allows the surface to be further profiled in order to optimize or influence the effect of the lubricant pockets.

The laser beam is particularly preferably moved linearly over the surface in such a way that adjacent line sections are produced alternately with a laser beam aligned perpendicularly and with a laser beam aligned at an angle. This results in a uniform formation of the surface with pockets of lubricant present therein.

Furthermore, it is preferably provided that the laser beam is moved linearly over the surface in such a way that the surface is given a wave-shaped surface profile as a result of the adjusted laser beam inclination. This results in the previously mentioned advantages of the uniform formation of the surface with lubricant pockets contained therein.

Furthermore, it is preferably provided that the laser beam is generated as an ultra-short pulse laser, in particular as a nanosecond, picosecond or femtosecond laser. The laser types mentioned are known and can therefore be used inexpensively in the alloying process. The ultra-short pulse laser introduces a particularly high energy density into the surface, which creates a depression in the form of the aforementioned lubricant pocket in the surface of the component even if the laser beam is not moved at the aforementioned angle to the surface, but also when the laser beam is perpendicular or nearly perpendicular to the surface. Instead of an inclined laser beam or a device that enables the laser beam to be inclined and positioned vertically, two laser beam sources are required for this variant.

In particular, the surface is first treated with a conventional laser beam, for example a disk laser beam, which is aligned perpendicularly to the surface and moved linearly over the surface, and only then in at least one line section by the ultra-short pulse laser, which is then also perpendicular or almost perpendicular to the surface of the tub component is aligned. Instead of tilting the laser beam, the surface is first oxidized or treated by conventional laser alloying with a vertical angle of incidence of the laser beam, and then the lubricant pockets are introduced into the already pretreated surface in a targeted manner using the ultrashort pulse laser. Optionally, the ultra-short pulse laser beam is aligned at an angle to the surface at an angle described above.

Furthermore, it is preferably provided that the at least one lubricant pocket is produced by an ultra-short-pulse laser beam or mechanically, for example by milling, and then at least partially treated by a disk laser beam. In particular, the flanks of the groove, ie the side walls of the groove, are treated and alloyed with the disk laser, preferably under an oxygen atmosphere. As a result, the surface is protected by an anti-wear layer and serves as a lubricant dispenser during operation thanks to the lubricant pockets, which reduces wear and friction losses.

The component according to the invention with the features of claim 10 is characterized in that the surface has at least one lubricant pocket extending linearly over the surface. This results in the advantages already mentioned above. In particular, the component is produced by the method according to the invention.

• 1A und 1B ein vorteilhaftes Verfahren zur Herstellung einer verschleißfesten Oxidschicht auf einem Aluminiumbauteil, und
• 2 eine Schnittdarstellung der durch das Verfahren hergestellten Oxidschicht.

Further advantages and preferred features and feature combinations result in particular from what has been described above and from the claims. The invention will be explained in more detail below with reference to the drawing. to show

• 1A and 1B an advantageous method for producing a wear-resistant oxide layer on an aluminum component, and
• 2 a sectional view of the oxide layer produced by the method.

1A and 1B each show a simplified representation of a method for producing a wear-resistant oxide layer 1 of a component 2, which is designed, for example, as a bearing part, in particular a friction or slide bearing part, or as a brake body of a motor vehicle. The component 2 has a surface 3 which, when used as intended, is in physical contact with a contact partner and, in particular, moves relative to the contact partner. This creates friction and wear between the two contact partners on their touching surfaces.

In order to increase the wear resistance of the component 2, it is known to provide the surfaces 3 used for physical contact with a wear protection layer or with a wear-resistant protective layer. According to the present embodiment, the component 2 is made of aluminum. In the case of aluminum components, it is known to produce a wear-resistant oxide layer on a surface as a protective layer by means of laser alloying. For this purpose, the surface is locally melted in an oxygen atmosphere with a laser beam, the aluminum then reacting with the surrounding oxygen and forming the oxide layer on the surface 3 .

1A shows a side view of the component 2 to which the oxide layer 1 is applied by means of laser alloying. In known methods, the laser beam 4 is aligned at an angle perpendicular to the surface 3 of the component 2 and is moved linearly over the surface 3, as shown in FIG 1A represented by a dashed laser beam. 1B shows a top view of the component 2 and the laser beam 4, which is moved linearly over the surface 3, in this case along lines 5 running parallel to one another, in order to treat the entire surface 3. The lines 5 lie parallel to one another and are aligned in a straight line, so that a simple sequence of movements of the laser beam 4 over the surface 3 is ensured.

According to the present exemplary embodiment, it is advantageously provided that the laser beam 4 is not aligned at an angle perpendicular to the surface 3, but at an angle α inclined obliquely to the surface 3. The angle α has a value of 35° to 70°, in particular 45° to 65°. As a result, the laser beam hits 4, as in 1A Drawn in with a solid line, obliquely on the surface 3, which results in an advantageous deformation in the surface 3 through the laser treatment or the laser alloying.

2 shows a simplified sectional view through the component 2 in the area of a line 5 generated by the laser beam 4 on the surface 3. While in conventional laser alloying processes, an at least essentially flat surface 3 of the oxide layer 1 is formed due to the laser beam being aligned perpendicularly to the surface 3 a wavy surface profile was created by the advantageous procedure according to the present exemplary embodiment. This is characterized by an indentation 6 and an elevation 7 adjoining it. This creates a lubricant pocket 8, in particular in the area of the depression 6, into which lubricant can be introduced and, if necessary, dispensed between the friction partners. The wavy or sinusoidal surface profile causes the depression to act as a lubricant reservoir or lubricant pocket 8 when lubricant is applied to the surfaces 3 of the component 2 . When there is a relative movement between the two friction partners, as described above, the contact surfaces are wetted by the lubricant or the lubricant, which creates an advantageous separating layer between the friction partners, which reduces wear and friction between the contact partners.

In particular, the laser alloying is carried out in an atmosphere with an oxygen content of at least 85%. For this purpose, the area treated by the laser beam 4 is optionally exposed to a stream of oxygen at the same time, as in 1A represented by a dashed arrow 9 applied.

According to an embodiment, all lines 5 on the surface 3 are treated by the laser 4 in the inclined orientation. According to a further exemplary embodiment, only every second line 5 is treated with the obliquely aligned laser 4, while the remaining lines are subjected to conventional laser alloying, in which the laser beam, as in FIG 1A represented by the history line, is oriented perpendicular to the surface 3 at an angle β.

According to a further exemplary embodiment, to produce the lubricant pockets 8, the surface 3 is first conventionally laser-alloyed, with a laser beam 4 aligned perpendicularly to the surface 3, as shown in FIG 1A shown by dashed lines. This laser beam is also drawn linearly over the surface 3, so that an at least essentially flat surface structure is created. The anti-wear layer or oxide layer 1 designed in this way is then post-treated with an ultra-short pulse laser. In particular, the ultra-short pulse laser is moved linearly, in particular parallel to the lines 5, over the surface 3 or the oxide layer 1. Due to the increased power of the ultra-short pulse laser compared to the laser used for the conventional laser alloy, for example a disk laser, depressions 7 also arise in the surface 3, which serve as pockets 8 of lubricant. For example, every second line 5 is post-treated by the ultra-short pulse laser. In particular, a nanosecond, picosecond or femtosecond laser beam is generated as an ultrashort pulse laser.

According to a further exemplary embodiment, at least one of the line sections or at least one of the lines 5 is first machined mechanically or by an ultra-pulse laser in such a way that a groove or groove-like depression 6 in the form of the lubricant pocket 8 is produced. Then, in particular, the flanks or side walls of the groove are alloyed by a disk laser in an oxygen atmosphere, as described above, in order to optimize the friction and wear properties of the surface 3 during operation.

QUOTES INCLUDED IN DESCRIPTION

This list of the documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• EP 2853616 B1 [0003]

Claims (12)

Method for producing a wear-resistant oxide layer (1) on an at least essentially flat surface (3) of a component (2), in particular an aluminum component, wherein the surface (3), in particular an aluminum surface, is provided with an oxide layer (1) by means of laser alloying, and a laser beam (4) being moved in a line over the surface (3) of the component (2) for the laser alloying, characterized in that a lubricant pocket (8) is introduced into the surface (3) in at least one line section and the laser beam (4 ) is processed. procedure after claim 1 , characterized in that the laser beam (4) is moved linearly in at least one line section at a predetermined angle (a) inclined to the surface (3) and/or is generated by an ultra-short pulse laser in order to create a lubricant pocket (8) in the line section form the surface (3). procedure after claim 2 , characterized in that the laser beam (4) is moved in the line section at an angle (a) of 40° to 70°, in particular of 45° to 65°, inclined to the surface (3). Method according to one of the preceding claims, characterized in that the laser alloying is carried out in an atmosphere with an oxygen content of at least 80%, in particular at least 85%. Method according to one of the preceding claims, characterized in that the laser beam (4) is moved over the entire surface (3) at the angle (a) inclined to the surface (3). Method according to one of the preceding claims, characterized in that the laser beam (4) is moved linearly in at least one line segment at an angle (β) perpendicular or almost perpendicular to the surface (3). Method according to one of the preceding claims, characterized in that the laser beam (4) is moved linearly over the surface (3) in such a way that adjacent line sections are produced alternately with a laser beam (4) aligned vertically and with a laser beam (4) aligned at the angle (a). . Method according to one of the preceding claims, characterized in that the laser beam (4) is moved linearly over the surface (3) in such a way that the surface (3) is given a wave-shaped surface profile as a result of the angle (a) set. Method according to one of the preceding claims, characterized in that the laser beam (4) is generated as an ultra-short pulse laser by a nanosecond, picosecond or femtosecond laser. procedure after claim 9 , characterized in that the surface (3) is first treated by a laser beam (4), in particular a disk laser beam, which is aligned perpendicularly to the surface (3) and is moved in a line over the surface (3), and then in at least one line section by the ultrashort pulse laser. Method according to one of the preceding claims, characterized in that the at least one lubricant pocket (8) is produced mechanically or by an ultra-short pulse laser beam and is then treated at least in regions by a disk laser beam. Component (2), in particular cylinder for a brake booster or slide or friction bearing for a motor vehicle, preferably produced by a method according to one of Claims 1 until 11 which has a wear-resistant oxide layer (1) produced by laser alloying on at least one at least essentially flat surface (3), characterized in that the surface (3) has at least one lubricant pocket (8) extending linearly over the surface (3). .

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