DE102009060924B4 - Production Method for a Solid Lubricant Structure A solid lubricant structure produced by the production method, and uses - Google Patents

Abstract

Production method for a solid lubricant structure, wherein on a substrate base (1) and / or connected to a substrate base (1) at least one layer (2a) comprising or consisting of diamond-like carbon DLC layer system (2) is formed, wherein either only in Layer system (2) or both in the layer system (2), as well as in the substrate base (1) a plurality of individual recesses (3a, 3b, ...), which together form a recess structure (3) is formed, and wherein recesses ( 3a, 3b, ...) of the recess structure (3) are partially filled with at least one solid lubricant (4), wherein the distance d (d1, d2) of adjacent recesses (3a, 3b, ...) of the recess structure (3) and / or the periodicity p of the depressions (3a, 3b,...) in the layer plane of the layer system (2) is between 80 nm and 500 .mu.m, the depth extent h of the depressions (3a, 3b, 5 nm and 50 microns, the la is the lateral extent l of the depressions (3a, 3b,...) in the layer plane of the layer system (2) between 10 nm and 250 .mu.m and / or where the aspect ratio A = h / l of the above depth extent h and the projecting lateral extent l.sub.0 , 1 to 10 and the laser irradiation of the substrate base (1) or the layer system (2) is performed by a plurality of coherent laser beams (7a, 7b, ...) in a superposition area (U) at a predefined angle (s) for interference and positioning the substrate base (1) or the layer system (2) at a predefined position in this overlapping area (U).

Description

The present invention relates to a production method for a solid lubricant structure, a solid lubricant structure prepared by the production method, and uses.

Solid lubricants that can be used under unfavorable conditions (eg in a high vacuum or under protective gas atmospheres) are already known from the prior art (C. Donnet, T. Le Mogne, M. Berlin and J.-M. Martin " Solid lubricant studies in high vacuum ", Proceedings of the sixth European space mecanisms & Tribology symposium, Technopark, Zurich, Switzerland, 4th to 6th October 1995, pp. 259 to 264).

The known technical solutions for tribologically stressed surfaces under unfavorable lubrication conditions generally use solid lubricants from the group of chalcogenides (eg MoS ₂ , WS ₂ , NbSe ₂ ), which are in the form of a powder, a lubricating varnish or else in other bonded form can be applied to surfaces by manual application, dipping, spraying or by plasma coating. An advantage of such solutions is that the solid lubricants adhere well to the surface under moderate load and in inert gases and in vacuum very low coefficients of friction (typically 0.03, sometimes even below) show.

A disadvantage of these solutions is on the one hand the low mechanical stability of the relatively soft solid lubricants and thus the loss of material even under moderate stress. A further disadvantage is that, in particular in the case of MoS _{2 which is} mostly used under moisture (ie already at normal air), the coefficient of friction increases to about 0.4. At the same time, the service life is drastically shortened. Thus, the use of the known technical solutions under changing environmental conditions (eg between vacuum and air) is to be seen at least critically.

So are in JP 2007 162045 A Described ways in which a layer of diamond-like carbon is structured. A solid lubricant can be used in conjunction with the structuring.

US 7,318,847 B2 relates to a structured layer system with a three-dimensional microstructure. Also diamond-like carbon can be used.

A method for producing oil pockets with small depth on mechanically stressed surfaces is in JP 2003 247691 A described.

WO 03/044383 A1 relates to a bearing and a composite structure with a microrough surface.

Self-lubricating slide bearings are from E. Dörre u. a. in "self-lubricating and maintenance-free plain bearings", Ehningen at Böblingen: Expert-Verlag, 1993, pages 8, 9, 223-241 described.

The use of diamond-like carbon layers in layer systems with improved tribological properties is described by J. Brand et al. a. in "The Variety of Carbon Layers - An Overview", Tribology + Lubrication Technology, 50th year, 3/2003, pages 18-22 described.

Possibilities for the use of microlens arrays to form holes go out GB 2 311 953 A out.

JP H10-258 383 A relates to a linear laser beam system for laser interference structuring.

A drive system for hard discs with low friction is out US 5,949,612 A known.

US 2009/0290824 A1 concerns rolling bearings, which can also be used in vacuum.

Low-friction rolling bearings intended to operate in a corrosive environment are known in WO 01/33091 A1 described.

A method and an apparatus for processing with laser pulses of large spectral width are in DE 103 33 770 A1 disclosed.

The US 2001/0031346 A1 also concerns layers of diamond-like carbon that achieve improved wear resistance and friction properties.

The object of the present invention is, starting from the prior art, to provide a solid lubricant structure (as well as a production method for such a structure) which has a low coefficient of friction and low wear as well as sufficient mechanical stability under any lubricated and unlubricated conditions which can be used even under changing environmental conditions (eg of air in vacuum or vice versa) without significant shortening of their life, which can be easily manufactured and which is insensitive to ionizing radiation, is thermally stable and exhibits a stable outgassing behavior.

This object is achieved by a manufacturing method according to claim 1. The claim 7 relates to solid lubricant structures produced by the method and the claim 17 are Uses. Advantageous embodiments of the structure and the manufacturing method can be found in the dependent claims.

The invention will first be described in general terms, then with reference to several embodiments. In the context of the present invention (the scope of which is defined by the claims), the individual features shown in combination within the scope of the exemplary embodiments need not be realized exactly in the configuration shown in the examples, but can also be realized in other combinations within the scope of the invention. In particular, individual features of the embodiments shown may also be omitted.

The basic idea of the invention is based on modifying a surface (for example a substrate base used to build up a solid lubricant structure according to the invention) by introducing depressions. This modification is combined with a coating of the surface with a layer system comprising at least one layer containing or consisting of diamond-like carbon (DLC). The layer system can also comprise a plurality of such diamond-like carbon-containing or consisting of individual layers. Solid lubricant (eg MoS ₂ ) is introduced into the recesses. By combining a deep structuring of the surface with the above DLC coating and with the introduction of the solid lubricant in the resulting wells, an advantageous friction / sliding behavior even under unfavorable lubrication conditions such. B. be ensured in a vacuum. Advantageously, the deep structuring or the surface modification takes place by means of a laser (laser structuring).

The present invention thus achieves the above object by a combination of a laser-structured, DLC-coated surface with a solid lubricant, which is introduced into the microwells of the recessed structure structured in the surface.

If, in the context of the present invention, a depression structure (having a multiplicity of individual depressions) or, for short, a depression in a substrate, in a layer system and / or in a layer is mentioned below, then in a surface (of the substrate, the layer system and / or a single layer of the layer system) recesses (cavities such as trenches or the like) to be understood. For this purpose, the considered structure (eg individual layer) does not necessarily have a variation in its (layer) thickness, if necessary, such a depression in a surface of this structure or layer can also be realized by (for the same layer thickness the layer) the underlying structure (eg substrate or substrate base) has a thickness variation or recess structure. Is so z. For example, when a substrate sinusoidally varying in thickness is coated with a DLC layer of constant thickness, the minima of the sinusoidal waveform not only form recesses of the substrate base but also depressions of the DLC layer.

A solid lubricant structure according to the invention thus has a substrate base (eg part of a tool surface) and a layer system formed adjacent to and / or connected thereto. The layer system contains at least one (possibly also several) layer (s) which consists of diamond-like carbon or contain this / contain. In the layer system (or in one or more individual layers of this system) alone or both in the layer system (or at least in one layer of this system) and in the substrate base a plurality of individual recesses is formed. The totality of the amount of depressions is also referred to below as a recess structure. Finally, at least some of the recesses are each at least partially filled with at least one solid lubricant.

In principle, it is therefore possible according to the invention to form the depression structure exclusively in the layer system (eg also bounded on both sides by further DLC monolayers without depressions), but it is likewise possible to form depressions, for example, in the substrate base. Trenching and then coating the surface of the substrate base having the recesses with the DLC layer system of constant thickness (so that the recesses of the substrate base are transferred to the DLC layer system) and finally filling the recesses in the DLC layer system with the solid lubricant , The depressions can thus run only within the layer system itself or from the layer system to the substrate base.

It is thus possible that portions of the recesses are formed only in the individual layers (or in the single layer) of the layer system, but not in the substrate base; it is also possible to provide recess sections both in the layer system (or at least in individual layers thereof) and in the substrate base.

Advantageously, a periodic recess structure in the layer system and / or in the substrate base is realized in one direction or in two (for example, perpendicular to one another) directions. Particularly advantageous distances adjacent individual recesses of such a recess structure (the corresponding distance then corresponds to the periodicity of the recesses), particularly advantageous expansions of the recesses perpendicular to the layer plane or substrate surface (depth), particularly preferred lateral expansions (in the layer plane) of the individual wells and particularly advantageous aspect ratios to be described in detail below. The aspect ratio of a depression is understood to be the ratio of its depth extent (perpendicular to the layer plane) and its lateral extent (in the layer plane).

Particularly advantageous periodic depression structures are one-dimensional or two-dimensional (that is to say intersecting in the latter at an angle of, for example, 90 °) trench structures consisting of a plurality of individual, linear trenches running parallel to one another and each with a constant trench spacing. However, it is also possible to provide periodic pit structures comprising a plurality of individual holes (dot patterns). These hole structures can be formed periodically in one or in two directions or dimensions. These two-dimensional structures can be realized with multi-beam interference or with the help of microlens arrays (see below).

In a further advantageous variant, the above-described layer system consists of exactly one single layer of diamond-like carbon DLC. It is also possible to form the layer system from a plurality of such DLC layers. The one or more DLC monolayer (s) advantageously contain predominantly amorphous carbon present in a mixture of graphitic and diamond-like chemical bonds. The structure of such layers is known in the art, they are, for example, in the VDI Guideline VDI 2840 "Carbon Layers: Fundamentals, Coating Types and Properties", November 2005 issue, s. there in chapter 4 the subitems 2.1. to 2.7., Described.

Advantageously, the individual carbon layer (s) may have a Vickers hardness between 1000 HV and 8000 HV and / or a layer thickness between 2 nm and 50 μm. The individual layers can also be formed as gradient layers in which the carbon content and / or the ratio of graphite-like diamond-like bonded carbon atoms in the direction perpendicular to the layer plane to the substrate base increases or decreases.

In order to ensure or improve the adhesion of the layer system or of the DLC layers to the substrate base, adhesion promoter layers can be provided between the layers or the layer system and the substrate base. The above-described depressions can then also be formed in these adhesion promoter layers.

As a substrate base, a ceramic, a metal and / or a plastic can be used. Also appropriate material combinations are conceivable. The substrate base may be, for example, the surface of a component or a tool.

In a production method according to the invention for a solid lubricant structure, a layer system containing at least one DLC layer is applied to a substrate base, it being possible to deposit an adhesion promoter layer before application of the layer system to the substrate base. The above-described recess structure is formed either only in the layer system or both in the layer system and in the substrate base and, if appropriate, the adhesion promoter layer. The recesses are then filled at least in sections with at least one solid lubricant.

In a first advantageous production variant, it is possible to irradiate the substrate base (eg via a microlens array or also by means of a direct laser interference method, see below) with laser radiation in order to incorporate recesses into the surface of the substrate base according to the invention. Subsequently, the DLC layer system can be deposited on the deep-structured surface of the substrate base (possibly after previous deposition of adhesion promoter layers). In this way, assuming a deposition of the layer system or of the individual layers of this system with a constant thickness, the depression structures of the substrate base in the form are also transferred unchanged to the layer system. In the wells thus formed in the layer system can finally (as will be described in detail below), the solid lubricant are introduced.

Alternatively or possibly also in combination with this procedure, it is likewise possible first to deposit the DLC layer system on a (eg flat or curved) surface of a recessless substrate base, before finally exposing the depressions of the recess structure by laser irradiation of the layer system applied to the substrate base be introduced into the layer system and / or the substrate base. Bonding agent layers can also be deposited here before the layer system is connected to the substrate base. After the laser irradiation of the already applied layer system or the deep structuring of substrate base and / or layer system, a further deposition of one or more DLC single layers take place before finally the solid lubricant is introduced into the wells created by the laser structuring.

In an advantageous variant, the laser irradiation of the substrate base and / or of the layer system takes place in that a laser beam is irradiated (advantageously focused) via a microlens array (which separates the laser beam into a plurality of individual beams) onto a defined surface (hereinafter: focus area). , The substrate base and / or the layer system is then, viewed in the laser beam direction, arranged behind the microlens array at a predefined position. This position can lie at a defined distance in front of the focus area, at the height of the focus area or at a defined distance behind the focus area: Depending on the setting, the lateral extent and / or the depth extent of the individual cavities of the recess structure can be set to a predetermined value (Minimum structure size with arrangement of substrate base and / or layer system in the area of the focus area, with increasing or decreasing distance to the focus area, the extent of the structured depressions increases).

Alternatively, it is also possible to cause a plurality of coherent laser beams to interfere at predefined angles in a superposition area. The substrate base and / or the layer system is hereby positioned at a predefined position in the interference or overlay region. Depending on the positioning of the substrate base and / or the layer system, the desired (periodic) structures with the desired lateral expansions and / or depth expansions can be realized at their maxima by the interference patterns arising in the interference region. The multiple laser beams can be generated by means of beam splitters and then beamed via beam deflectors (eg mirrors) from different directions or at the desired angles into the overlapping area.

The laser irradiation can be pulsed or continuous; Lasers with emissions in the visible or in the infrared range are just as applicable as lasers with emission wavelengths in the UV range.

Advantageously, the coating system is applied to the substrate base (or to corresponding adhesion promoter layers) by means of a coating method. The chemical vapor deposition can be used as well as the physical. An application of the layer system is possible in particular by means of plasma-assisted chemical vapor deposition, by magnetron sputtering and / or by means of a vacuum arc process. The adhesion promoter layers can also be deposited accordingly.

The filling of the wells with solid lubricant can be done by mechanical introduction of present in paste form of solid lubricant. Also in powder form mixed with at least one organic and / or inorganic binder present solid lubricant can be introduced. Alternatively, a spray position of a solid lubricant present in liquid form is possible, as is immersion of the depressions introduced in the substrate base and / or the layer system into a solid lubricant-containing liquid.

After the introduction of the solid lubricant in the wells, a post-treatment in the form of drying, curing, sintering and / or firing can take place.

Thus, according to the invention, a planar or contoured surface of a component or a tool before or even after coating with a DLC layer with a μm or nm depth structure by direct laser interference and / or by using microlens arrays using preferably pulsed Laser radiation in the UV range, in the visible range and / or in the IR range are structured. It is also possible first to pattern a plastic, ceramic or metal substrate with the laser before coating with the DLC layer, as well as first to deposit the DLC layer on a corresponding substrate and then perform the laser patterning after deposition , In the latter case, after the laser structuring again DLC-coated.

The DLC coating can be made using PVD techniques (eg, arc evaporation or magnetron sputtering), PECVD techniques, or a combination of both. Single layers, multiple layers or even gradient layers can be deposited as DLC layers. Advantageously, layers of amorphous carbon z. B. type a-C, ta-C, a-C: H and / or ta-C: H and optionally also doped with a metal or other elements types such. B. a-C: H: W deposited as DLC layers (see VDI Guideline 2840). Advantageously, these layers have a hardness between 1000 HV and 8000 HV and a layer thickness between 2 nm and 50 microns.

• – linienartige Muster mit periodischem Abstand d (Periode p ist gleich Linienabstand d).
• – kreuzartige Muster erreicht durch Mehrfachbestrahlung mit Linienmustern mit einem spezifischen Rotationswinkel von z. B. 30°, 60° oder 90°.
• – kombinierte kreuzartige Muster mit unterschiedlichen Linienabständen d₁ und d₂.
• – verschiedene Anordnungen von Vertiefungen z. B. in Form von Löchern mit unterschiedlichen Abständen.
• – beliebige Formen von Vertiefungen bzw. Löchern mit einem Mikrolinsen-Array über der zu strukturierenden Substratbasis und/oder Schicht.
• – beliebige Formen von Vertiefungen über ein Verschieben der Substratbasis und/oder Schichtstruktur während der Bestrahlung über ein Mikrolinsen-Array.
• – beliebige Formen von Vertiefungen mit einer Verschiebung der Bestrahlungsoptik während/zwischen den Bestrahlungen über ein Mikrolinsen-Array.
• – linienartige Muster über ein Mikrolinsen-Array.
• – kreuzartige Muster durch Mehrfachbestrahlung mit Linienmustern mit einem Mikrolinsen-Array.
• – auch beliebige Kombinationen der vorbeschriebenen Musterstrukturen sind denkbar.

The structures introduced by the laser structuring can be formed as follows:

• - Line-like pattern with periodic distance d (period p is equal to line distance d).
• - Cross-like pattern achieved by multiple irradiation with line patterns with a specific rotation angle of z. B. 30 °, 60 ° or 90 °.
• - Combined cross-like patterns with different line spacing d ₁ and d ₂ .
• - Different arrangements of wells z. B. in the form of holes with different distances.
• Any shapes of pits or holes with a microlens array over the substrate base and / or layer to be patterned.
• Any shapes of depressions via a displacement of the substrate base and / or layer structure during the irradiation via a microlens array.
• Any shapes of pits with a shift of the irradiation optics during / between the irradiations via a microlens array.
• Line-like patterns over a microlens array.
• - Cross-type patterns by multiple irradiation with line patterns with a microlens array.
• - Any combinations of the above pattern structures are conceivable.

The structures thus produced are finally filled with a solid lubricant, so that the structures are at least partially filled. Excess solid lubricant may possibly remain on the filled surface. The solid lubricant may consist of sulphides (eg MoS ₂ , WS ₂ ), selenides (for example NbSe ₂ ), graphite, plastic (eg PTFE particles) and / or of soft metals (eg Al, Co, Pb) or also consist of any mixture of the aforementioned substances. It can be present in powdered or else in liquid-bound form. The solid lubricant can be introduced, for example, by immersion, spraying or by simple manual application in the wells and optionally aftertreated (eg by sintering or heat drying).

Compared to the solid lubricant structures known from the prior art, the greatest advantage of the present invention lies in the fact that the surfaces produced have good sliding and anti-wear properties under the most difficult ambient and / or lubricating conditions (in particular even in a vacuum).

Another advantage lies in the wide tolerance range of environmental conditions under which the surface according to the invention retains its sliding properties.

Pure DLC coatings are known to exhibit good anti-slip and anti-wear properties under mixed-friction conditions as well as in normal atmospheres but lose their advantageous properties under very dry air, inert gas, vacuum or other difficult environmental conditions, producing high coefficients of friction and high wear. By the invention z. B. introduced via a laser structuring wells and their filling with solid lubricant in combination with the DLC coating, a reservoir of lubricant is provided, which always holds the necessary lubricant even under unfavorable environmental conditions, without this is consumed quickly. Thus, a modified DLC layer modified according to the invention or provided with filled depth structures can be used almost universally. The invention can be used in the range of all tribologically loaded components and components, in particular for components and components that are otherwise insufficiently supplied with lubricant due to heavy loads, constructive aspects or due to the prevailing environmental conditions.

In particular, the surfaces modified according to the invention or the solid lubricant structures according to the invention are suitable for mechanical components such as bearings, gears or guides in vacuum applications (for example in space applications such as satellite positioning systems or in vacuum pumps) and under protective gas (eg in microelectronics applications).

Further examples of the application of solid lubricant structures according to the invention are tribologically highly stressed parts, for. In the automotive sector (distributor pumps, injection components, piston rings, piston pins, gears in gears). Finally, dry running friction / sliding pairings (eg for machine tools, textile machines or even in aircraft applications) are fields of use for solid lubricant structures according to the invention.

Hereinafter, the present invention will be described in detail with reference to embodiments.

Show it:

1 the structure of two inventive solid lubricant structures.

2 various pit structure forms of the present invention.

3 a microlens array configuration for carrying out a manufacturing method according to the invention.

4 different microlens arrays for the construction according to 3 ,

5 a direct laser interference structuring structure for a manufacturing method according to the present invention in two-beam configuration.

6 a corresponding structure in three-beam configuration.

7 a corresponding structure in four-beam configuration.

8th a schematic diagram of the inventive generation of a recess structure in a substrate base by laser interference.

9 to 11 in two-, three- or four-beam configuration generated intensity pattern.

12 to 14 Examples of DLC layer systems structured according to the invention.

Unless otherwise stated below, the embodiments relate to a solid lubricant structure comprising a hardened steel substrate base, e.g. B. 100Cr6, on which by means of a PVD coating process, a 2.5 micron thick homogeneous layer of Ta-C is deposited. Before depositing, the substrate base (hereinafter also referred to as a component) is cleaned in a conventional manner and first a plasma cleaning and a deposition of an adhesion-promoting layer are carried out in the coating chamber, before finally the homogeneous layer of ta-C is coated. The deposition of the ta-C layer is carried out using a pulsed vacuum arc method, for. B. with a laser arc process from a graphite cathode. In this case, the coating is preferably carried out with a plasma filter in order to deposit the smoothest possible layer.

After the laser structuring of the substrate base and / or of the layer system before or after the coating of the substrate base (the laser structuring will be described in detail below), the solid lubricant is applied to the surface structured in this way. The application of the solid lubricant can be done in a conventional manner, such as. B. Bhushan, BK Gupta Handbook of Tribology: Materials, Coatings and Surface Treatments, McGraw Hill Inc., New York 1991. For example, paste-like solid lubricants are applied in accordance with instructions with brushes or cloths, bonded coatings (eg conventional, air-drying bonded coatings based on MoS ₂ ) are sprayed in accordance with regulations and sliding films are applied according to the instructions by means of dipping. In addition to air-drying products, thermosetting products can also be used. Excess solid lubricant, z. B. excess lubricating varnish can be removed by wiping from the structured surface, so that only in the formed wells of the structured surface remains solid lubricant. However, it is also possible to leave excess solid lubricant application on the structured surface protruding.

1 shows in cross section perpendicular through the layer system level (here: plane of the ta-C layer) two different solid lubricant structures according to the invention.

When in 1a) example shown is first on the steel substrate base 1 (After depositing a primer layer not shown), the ta-C layer 2a , here the only layer of the layer system 2 trains, isolated. Then, using a z. B. via a microlens array (see below) guided laser beam a periodic recess structure 3 in the shift system 2 or the ta-C layer 2a einstrukturiert. The parameters of the laser irradiation are chosen so that the wells 3a . 3b , ... of the specialization structure 3 exclusively in the ta-C layer 2a be formed, so do not extend to a depth in which the layer 2a facing surface O1 of the substrate base 1 or the boundary between layers 2a and substrate base 1 lies.

The here periodic deepening structure 3 comprises a plurality of individual, linearly extending, parallel to each other at constant intervals d arranged, rectangular in cross-section trenches 3a . 3b , ... as depressions. The thickness of the ta-C layer 2a here is 2.5 microns, the depth h of the wells 3a . 3b , ... perpendicular to the layer plane 1.25 μm, the distance d between two adjacent trenches 3a . 3b , ... (ie, the periodicity p = d) is here 10 microns and the lateral extent l of the trenches in the layer plane and perpendicular to the trench longitudinal axis is here l = 5 microns (the representation is therefore not to scale).

After introducing the recess structure 3 in the layer 2a an entry of the solid lubricant takes place 4 in the form of z. B. MoS ₂ in the individual wells 3a . 3b , as described above. The wells are here completely with solid lubricant 4 refilled. Solid lubricant, over the substratumbasisabgewandte side (surface O2) of the layer system 2 survives, is removed.

1b) shows a second example of a solid lubricant structure according to the invention in cross section; the structure is basically the same as in 1a) case, so only the differences are described below.

In 1b) does not become the shift system 2 but the substrate base 1 using the laser structured before the primer layer (not shown) and the layer system 2 be applied. The adhesion promoter layer and the layer system 2 be with a constant layer thickness (here, for example, 1 micron for the layer 2a ) on the already structured, that is provided with depressions surface O1 of the substrate base 1 deposited. Because of this, those in the substrate base 1 formed depressions on the layer system 2 transferred, so that the recess structure 3 here both in the substrate base 1 , as well as in the shift system 2 is trained. The clear widths of these depressions 3a . 3b , ... (with the height or depth h and the lateral extent l) are completely filled with solid lubricant 4 filled; via the substrate-remote surface O2 of the layer system 2 out standing solid lubricant is removed.

2 shows different periodic pit structures 3 formed by laser structuring and parallel to the layer plane and / or the surfaces O1 and O2 running in the substrate base 1 and / or in the shift system 2 can be trained. So shows 2a) a one-dimensional trench structure G1, in which a plurality of parallel trenches spaced from each other. The distance d of immediately adjacent trenches or the periodicity p in the direction R1 perpendicular to the trench longitudinal axes can be, for example, between 1 μm and 100 μm.

2 B) shows a superposition of two such trench structures at an angle α ≠ 0 ° (here: α = 70 °): For example, first using a cylindrical lens microlens array, the first trench structure G1 (trench spacing d1) are generated in the direction of R1, before the substrate base 1 with the layer system 2 is rotated by α, and then by renewed laser irradiation by the cylindrical lens microlens array, the second trench structure G2 (trench spacing d2) in the direction R2 (which is then rotated by α with respect to the direction R1) to generate.

2c) shows the case 2 B) in which α = 90 °, that is two perpendicular to each other and in the substrate base 1 and / or the layer system 2 formed trench structures G1, G2 (cross lattice).

2d) shows an example where the pit structure 3 is not in the form of one or more trench structure (s), but comprises a plurality of individual holes LO. The holes LO are arranged at the crossing points of a square lattice, so that there is a two-dimensional periodicity of the recess structure in two mutually perpendicular directions R1 and R2 (the hole pitch d1 in the direction R1 and the hole pitch d2 in the direction R2 are identical here). For example, d1 = d2 = 150 μm and a hole diameter l in the layer plane of 30 μm and a hole depth h perpendicular to the layer plane of 10 μm are selected. The aspect ratio a = h / l = 10 μm / 30 μm is thus 0.3.

2e) shows another case of a periodic hole structure as in FIG 2d) , but here the two directions R1 and R2, in which the individual holes LO are arranged in each case at periodic intervals in rows, not perpendicular to each other, but form an angle of α = 70 °.

3 shows a first structure for producing a solid lubricant structure according to the invention. The structure comprises a laser (not shown), for example a UV-emitting laser with a wavelength of λ = 266 nm. The laser beam 5 This laser is here in pulsed form (but it can also be a continuous laser beam are generated, the element 10 then omitted) first by a device 10 to control the number of pulses, here a mechanical shutter, blasted. Behind the mechanical shutter 10 is in the beam path of the laser beam 5 a homogenizer 11 arranged. The homogenizer consists of a system of optical elements, the z. B. generate a top-has beam profile. In the beam path 5 behind the homogenizer 11 is a telescope system 12 arranged to control or for adjusting a desired beam diameter. This follows in the beam path 5 a diaphragm (here: iris diaphragm) or also a rectangular diaphragm 13 before the laser beam 5 finally on a microlens array 6 meets. The aperture 13 is used to calculate the beam outline and beam diameter of the laser beam 5 to bring to a predetermined shape (eg, rectangular) and size. The order of the components 10 to 13 This can be different than in 3 be selected. If necessary, you can access the elements 10 to 13 be waived.

The microlens array 6 Here, a cylindrical lens microlens array with a plurality of in a plane parallel to each other and at constant distances from each other arranged cylindrical lenses (the longitudinal axes are arranged here perpendicular to the plane shown). The individual cylindrical lenses of the microlens array 6 have a focus distance f. Through the microlens array 6 becomes the laser beam 5 thus in a variety of individual sub-beams 5a . 5b . 5c , ..., split at a distance f behind the microlens array 6 be focused on a flat surface F.

By means of a movable in the three translational directions x, y and z of a Cartesian coordinate system moving table 14 that's it substratum 1 with the layer system 2 (the latter is not shown here) aligned so that the substrate base surface O1 and the layer system surface O2 (see. 1 ) are aligned parallel to the focal surface F. In the case shown, the surface O1 of the layer system and the focus area F coincide, so that the partial beams 5a . 5b , ... are focused on this surface (focus distance f equals the distance of the array 6 from the surface O1). By a suitable choice of the beam parameters of the laser beam 5 are thus at the place of incidence of the partial beams 5a . 5b , ... in the elements 1 and or 2 above-described specialization structures 3 generated.

For setting the structure size of the recess structure 3 can the distance a between microlens array 6 and substrate base 1 To be changed: By moving the substrate base 1 by means of the sliding table 14 in the + z direction, the focal plane F becomes behind the surface O1 of the substrate base 1 inside the substrate base 1 postponed; it then becomes pits 3a . 3b , ... produced with increased lateral extent l. The same happens with a method in the -z direction, since the focal plane F then outside the substrate 1 and before that lies. In order to control the structure size of the recess structure, the distance a can thus be selected to be greater or smaller than the focal distance f. In addition, it is possible by translation of the substrate 1 in the x and / or y direction by means of the displacement table 14 create different well structure geometries of controlled size.

Instead of a sliding table (with or without rotation axis), a robot can be used. Here, both the components 6 and 10 to 13 as well as the substrate base 1 be coupled with the translation table and / or robot. When arranging the components 6 and 10 to 13 at a corresponding translation table or robot, it is advantageous to use fiber-coupled lasers.

4a) again outlines how about a change in the distance a relative to the focal distance f (variation of the distance of the substrate relative to the microlens array), the structure size, that of the substrate base 1 and / or the layer system 2 is restructured, can be changed. 4b) to f) shows that different microlens arrays can be used: Line-generating microlens arrays with cylindrical ( 4b) ), dot-producing microlenses with crossed cylindrical ( 4c) ) Microlenses, hexagonal ( 4d) ) or square ( 4e) ) Lens arrays and square microlens arrays ( 4f) ). All of these microlens arrays 6a to 6b from the 4b) to 4f) can thus be in 3 shown construction can be used.

When in the 3 and 4 shown construction can use different laser wavelengths. For pulsed lasers (with pulse lengths eg in the nanosecond, picosecond or femtosecond range), various processes such as erosion, reflow, phase transformation, local hardening, etc. can be used to form the well structure 3 in the elements 1 . 2 be achieved. Likewise, direct surface modifications are possible with a laser pulse. The number of laser pulses can be varied to suit the shape and depth of the surface modifications 3 to control.

Also, the laser intensity can be varied to different geometries of the modifications 3 to obtain.

5 shows a structure for a direct laser interference patterning for the production of a solid lubricant structure according to the invention. A pulsed laser beam 7 with predefined intensity is first through a device 10 to control the number of pulses (here: mechanical shutter) blasted (alternatively, a continuous laser beam can be used, in this case, the device 10 possibly omitted). In the beam path after the device 10 is a homogenizer (here: a cylindrical or rectangular aperture) 11 arranged. The laser beam leaving the homogenizer is passed through a telescope system 12 , with which the beam diameter is brought to a predefined, desired size (eg 5 mm), blasted. The telescope system 12 follows an aperture (eg iris diaphragm) or a rectangular diaphragm 13 to arrive at a predefined, desired shape (eg rectangular) and beam size.

In the beam path after the aperture 13 follows a first, here also the only beam splitter 8a with which the laser beam 7 in two partial beams 7a and 7b is separated. The first partial beam 7a is arranged over two beam deflectors arranged in the beam path in the form of mirrors 9b and 9c deflected and finally at a predefined angle to the substrate 1 including layer system 2 (not shown here). The substrate base 1 is here, similar to in 3 shown on a sliding table 14 arranged. The the beam splitter 8a leaving second partial beam 7b gets over another mirror 9a deflected and also at a defined angle to the substrate 1 and the shift system 2 irradiated. The two aforementioned irradiation angle of the two partial beams 7a and 7b are formed so that the two partial beams at an angle β of z. B. 30 ° to each other and cross in a superposition area U or overlay. In this overlapping area U, in which the two partial beams 7a . 7b Cross, that is overlay, is the element 1 . 2 arranged in the surface of the recess structure 3 is to bring. The angle β between the two laser beams 7a . 7b can be varied to produce structures of different periodicity. Using the sliding table 14 can be a move of the elements 1 . 2 so that large, flat as well as non-planar (eg cylindrical) surfaces deep-structured 3 can be. The displacement can be both orthogonal to the beam axis 7 (eg lateral or vertical), parallel to the beam axis 7 and / or from a rotation of the elements 1 . 2 consist. The lateral extent l and / or the depth h of the structures 3 can be set via the beam intensity, irradiation duration and / or number of pulses.

8th outlines the overlay area U 5 in detail: Both rays overlapping at the angle β 7a . 7b form in the overlapping area U, in which the surface of the substrate base 1 or the substrate base 1 is arranged, an interference pattern at the maxima of a periodic deep structuring 3 of the substrate 1 (at the nodes of the interference structure lying between the maxima there is no deep structuring of the substrate, since here the incident intensity is lower (possibly also zero)).

The in the 5 and 8th Thus, the direct laser beam interference patterning technique shown enables the production of periodic two-dimensional or three-dimensional microstructures on almost all types of substrate surfaces and component geometries. To generate an interference structure, N (with N ≥ 2) become collimated and coherent laser beams 7a . 7b , ... on a surface 1 . 2 superimposed. This also results in particular the advantage that both flat, and not flat, curved surfaces can be structured, since the interference in the entire overlapping volume of the individual partial beams 7a . 7b , ... takes place.

6 and 7 show two further structures for direct laser interference patterning. These are basically like the ones in 5 shown construction, so that only the differences are described below: When in 6 shown construction is a three-beam structure, in which two successive in the beam path of the laser beam 7 introduced beam splitter 8a . 8b a split into three individual partial beams 7a . 7b and 7c done, then using appropriate mirror 9a to 9d from three different directions, ie at different angles to the substrate 1 be irradiated. The three partial beams 7a to 7c thus also overlap in a superposition area U, in which the substrate 1 is arranged. 7 shows a corresponding four-beam arrangement, in which over three consecutive in the beam path of the laser radiation 7 arranged beam splitter 8a to 8c a splitting of the beam 7 in a total of four different partial beams 7a to 7d takes place, in turn, by means of differently arranged and aligned beam deflector 9a to 9e from four different directions on the arranged in the overlay area U substrate 1 be irradiated. Here, too, all four individual rays intersect or overlap 7a to 7d in the overlay area U.

9 shows an example of one by two individual partial beams (b) 7a . 7b produced (a) line-like interference structure and another example of one by superposition or interference of a total of three sub-beams 7a to 7c (d) generated hexagonal point-like interference structure (c) (I = intensity).

10 also shows examples of interference structures by interference of two individual beams (d), three individual beams (e) or four individual laser beams (f): Two-beam interference results in a linear intensity distribution I (a), by three Beam interference in symmetric beam configuration in 10 (b) shown interference structure with interference maxima of equal intensity and by four-beam interference with the beam configuration shown in (f) an interference structure I with maxima of different intensity (c).

11 shows another example of an interference structure by four-beam interference (I = intensity, x and y denote two orthogonal directions in the layer plane of the layer system 2 or tangential to the surface of the substrate base 1 ).

12 to 14 show further examples of laser structuring according to the present invention using the interference method or using microlens arrays. The structuring can be carried out with different wavelengths in the UV, in the IR or in the visual range (for example 266 nm, 355 nm, 532 nm or 1064 nm) by using one or more laser pulses with pulse durations from a few femtoseconds to several nanoseconds , The laser fluence (incident energy per unit area) of each individual laser pulse can be varied, for example, in the range from a few mJ / cm ² up to several J / cm ² . In the examples shown the 12 u. 13 A pulsed 10 ns UV laser with a wavelength of 355 nm was used to detect the different DLC layer systems 2 Deep restructure on steel and on silicon 3 , with energy densities (laser fluence) between 60 and 900 mJ / cm ² .

12 and 13 show examples of direct laser interference patterning.
12a) : λ = 355 nm, laser fluence: 80 mJ / cm ² , 1 laser pulse, pulse duration: 10 ns, period spacing d = 180 nm, sample (substrate base and / or layer system) 1, 2: 100 nm DLC layer on silicon substrate ( Atomic force microscopic picture).
12b) : λ = 355 nm, laser fluence: 100 mJ / cm ² , 1 laser pulse, pulse duration: 10 ns, period spacing d = 240 nm, sample 1, 2: 80 nm DLC layer on silicon substrate (atomic force microscope image).
13a) : λ = 355 nm, laser fluence: 470 mJ / cm ² , 1 laser pulse, pulse duration: 10 ns, period spacing d = 4.7 μm, sample 1, 2: 2.5 μm DLC layer on steel substrate (scanning electron micrograph).

13b) : Shows the surface embossing of two orthogonal staggered line structures. Two line structures were generated one after the other, whereby the substrate was rotated by 90 ° before the application of the second line structure. λ = 355 nm, laser fluence = 0.9 J / cm ² , 50 laser pulses per line pattern, pulse durations: 10 ns, period spacing d = 10 μm, sample 1, 2: 2.5 μm DLC layer on steel substrate (scanning electron micrograph).

13c) : Shows the surface embossing of two orthogonal staggered line structures. Two line structures were generated one after the other, whereby the substrate was rotated by 90 ° before the application of the second line structure. λ = 355 nm, laser fluence = 470 mJ / cm ² , 30 laser pulses per line pattern, pulse durations: 10 ns, period spacing d = 10 μm, sample 1, 2: 2.5 μm DLC layer on steel substrate (scanning electron micrograph).

14 finally shows two more examples of deep structuring 3 a sample 1, 2, which was carried out by means of a microlens array.

14a) : λ = 266 nm, laser fluence (impinging on the microlens array) = 60 mJ / cm ² , 10 laser pulses, pulse durations: 10 ns, period spacing d = 120 μm, hole diameter l approx. 30 μm. The microlens array used was a point-generating array with a square lattice structure (120 μm pitch size). Sample 1, 2 is a 2.5 μm DLC coating on a steel substrate (optical microscope image).

14b) : λ = 355 nm, laser fluence (when hitting the microlens array) = 80 mJ / cm2, 10 laser pulses, pulse durations: 10 ns, period spacing d = 300 μm, line width or lateral extent of the structured trenches l approx. 35 μm. The microlens array used is designed as a line generator (parallel cylindrical lens arrangement) with a pitch of 300 μm. Sample 1, 2: 2.5 μm DLC layer on steel substrate (optical microscope image).

Claims (17)

Manufacturing method for a solid lubricant structure, wherein on a substrate basis ( 1 ) and / or connected to a substrate base ( 1 ) at least one layer ( 2a ) comprising or consisting of diamond-like / DLC carbon layer system ( 2 ), whereby either only in the layer system ( 2 ) or both in the shift system ( 2 ), as well as in the substrate base ( 1 ) a plurality of individual wells ( 3a . 3b , ...), which together form a specialization structure ( 3 ), and wherein depressions ( 3a . 3b , ...) of the specialization structure ( 3 ) partially with at least one solid lubricant ( 4 ), the distance d (d1, d2) of adjacent depressions ( 3a . 3b , ...) of the specialization structure ( 3 ) and / or the periodicity p of the recesses ( 3a . 3b , ...) in the layer plane of the layer system ( 2 ) is between 80 nm and 500 μm, the depth extent h of the depressions ( 3a . 3b , ...) is between 5 nm and 50 μm, the lateral extent l of the depressions ( 3a . 3b , ...) in the layer plane of the layer system ( 2 ) is between 10 nm and 250 μm and / or wherein the aspect ratio A = h / l of the above depth extension h and the protruding lateral extent l is 0.1 to 10 and the laser irradiation of the substrate base ( 1 ) or the layer system ( 2 ) is carried out by several coherent laser beams ( 7a . 7b , ...) are brought into interference in a superposition area (U) at a predefined angle (s) and in that the substrate base (FIG. 1 ) or the layer system ( 2 ) is positioned at a predefined position in this overlay area (U). Manufacturing method according to the preceding method claim, characterized in that before the formation of the layer system (s) ( 2 ) by laser irradiation of the substrate base ( 1 ) Depressions in a surface (O1) of the substrate base ( 1 ) are introduced so that then the layer system ( 2 ) is applied to this surface (O1) or connected to this surface (O1) in such a way that in the substrate base (O1) 1 ), in the layer system ( 2 ) or in the substrate base ( 1 ) facing away from the surface (O2) of this layer system ( 2 ) the specialization structure ( 3 ) with their depressions ( 3a . 3b , ...), wherein preferably after the laser irradiation one or more adhesion promoter layer (s) are applied to the surface (O1). Manufacturing method according to the Vorvorhergehenden method claim, characterized in that on a recessless surface (O1) of the substrate base ( 1 ) first the layer system ( 2 ) is formed before, by laser irradiation of the applied layer system ( 2 ) the depressions ( 3a . 3b , ...) of the specialization structure ( 3 ), wherein before forming the layer system ( 2 ) first on the surface (O1) of the substrate base ( 1 ) a bonding agent layer is applied before the application of the layer system ( 2 ) he follows. Manufacturing method according to one of the two preceding method claims 2 or 3, characterized in that the laser irradiation of the substrate base ( 1 ) or the layer system ( 2 ) is carried out by a laser beam ( 5 ) through a microlens array ( 6 ) and thereby into several individual beams ( 5a . 5b , ...), which are blasted onto a preferably flat surface (F) and the substrate base ( 1 ) or the layer system ( 2 ) seen in the laser beam direction behind the microlens array ( 6 ) is positioned at a predefined position, or multiple laser beams ( 7a . 7b , ...) by means of at least one beam splitter ( 8a . 8b , ...) from a single laser beam emitted by a laser ( 7 ) and using at least one beam deflector ( 9a . 9b , ...) into the overlay area (U). Manufacturing method according to one of the preceding method claims, characterized in that the application and / or bonding of at least one of the layers ( 2a ) of the layer system, on / with the substrate base ( 1 ) and / or the application of a primer layer to the substrate base ( 1 ) by means of a coating process selected from physical vapor deposition (PVD), plasma assisted chemical vapor deposition (PECVD), magnetron sputtering and pulsed vacuum arc processes. Manufacturing method according to one of the preceding method claims, characterized in that in the recess (s) ( 3a . 3b , ...) of the specialization structure ( 3 ) filled solid lubricant ( 4 ) is dried after drying, cured, sintered or fired. A solid lubricant structure produced by a manufacturing method according to any one of the preceding claims. Solid lubricant structure according to the preceding claim, characterized in that that of the substrate base ( 1 ) facing away from the surface (O2) of the layer system ( 2 ) towards the layer system ( 2 ) facing away from the substrate base seen the wells ( 3a . 3b , ...) starting from this surface (O2) either only within the layer system ( 2 ), or from the shift system ( 2 ) into the substrate base ( 1 ). Solid lubricant structure according to one of the preceding claims 7 or 8, characterized in that only in at least one of the layers of the layer system ( 2 ) at least portions of the recesses ( 3a . 3b , ...) of the specialization structure ( 3 ) are formed, but not in the substrate base ( 1 ), whereby the layer system ( 2 ), the recessless surface (O1) of the substrate base is formed as a flat or curved surface, or that in at least one of the layers of the layer system ( 2 ), as well as in the shift system ( 2 ) facing surface (O1) of the substrate base ( 1 ) at least portions of the recesses ( 3a . 3b , ...) of the specialization structure ( 3 ) are formed. Solid lubricant structure according to one of the preceding claims 7 to 9, characterized by a recessed structure formed periodically in one direction (R1) ( 3 ) or a recess structure formed periodically in two mutually at an angle (α) of not equal to 0 °, preferably of 90 °, (R1, R2) ( 3 ) is trained. Solid lubricant structure according to the preceding claim, characterized in that the periodic recess structure ( 3 ) one of a plurality of individual, linear, parallel to each other and each with a constant trench spacing (d, d1) extending trenches extending trench structure (G1) or a two such at an angle (α) of not equal to 0 °, preferably from 90 °, crossing Trench structures (G1, G2) having the same or different trench spacing (d1, d2) having structure. Solid lubricant structure according to the preceding claim, characterized in that the periodic recess structure ( 3 ) comprises a periodic hole structure having a multiplicity of holes (LO), wherein the holes (LO) of this hole structure are arranged in two directions (R1, R2) which are at different angles (α) from directions other than 0 ° at periodic intervals (d1, d2) are formed. Solid lubricant structure according to one of the preceding claims 7 to 12, characterized in that at least one of the diamond-like carbon DLC-containing or consisting of layers of the layer system ( 2 ) is an amorphous carbon-containing or consisting of layer. Solid lubricant structure according to one of the preceding claims 7 to 13, characterized in that the at least one of the DLC-containing or consisting of layers of the layer system ( 2 ) is formed as a gradient layer, wherein the carbon content and / or the ratio of graphite-like diamond-like bonded carbon atoms in the direction perpendicular to the layer plane to the substrate base increases or decreases. Solid lubricant structure according to one of the preceding claims 7 to 14, characterized in that between the substrate base ( 1 ) and the substrate base ( 1 ) nearest layer of the layer system ( 2 ) one the liability of the layer system ( 2 ) on the substrate base ( 1 ) is arranged ensuring or at least improving adhesion promoter layer. Solid lubricant structure according to one of the preceding claims 7 to 15, characterized in that the solid lubricant ( 4 ) contains or consists of at least one (s) of the following chemical elements, chemical compounds, minerals and / or substances and / or a mixture thereof: a sulfide of a transition metal, in particular MoS ₂ and / or WS ₂ , a selenide of a transition metal , in particular NbSe ₂ , graphite, a plastic or particles thereof, a ceramic or particles thereof, or a soft metal or particles thereof, in particular Al, Cu and / or Pb or alloys thereof. Use of a solid lubricant structure or a production method according to one of the preceding claims in the range of mechanical components designed for use in a vacuum or under protective gas, in particular bearings, gear components, guides, satellite adjustment systems or vacuum pumps, in the field of tribologically stressed parts in the automotive industry, in particular distributor pumps, injection components, Valve train components, piston rings, piston pin or gear wheels, or in the range of dry-running friction / sliding pairings, especially in machine tools, textile machinery or aircraft.

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