DE102016003036A1 - Method for coating a substrate, coating for a substrate and sliding element - Google Patents

Abstract

A method is proposed for coating a substrate (3), wherein a first layer (5) of amorphous carbon is arranged on the substrate (3) and nanoparticles (7) are arranged on the first layer (5).

Description

The invention relates to a method for coating a substrate, a coating for a substrate and a sliding element with such a coating.

From the European patent application EP 2 574 685 A1 For example, a slider with a DLC coating on a substrate emerges. A softer material is embedded as a DLC in a surface of the DLC coating with which the slider is to come into contact with a sliding partner against which the slider is to slide. A disadvantage of such layers, which in themselves offer good friction reduction and good wear protection for sliding elements, is that they can rapidly corrode and / or degrade in contact with chemicals, in particular in an environment which comprises engine oil. This increases the wear of such coatings. In this case, their increased wear can be explained by a reactivity of certain components of the DLC coating, in particular of hydrogen and / or metal atoms, with the constituents of the engine oil. Typical types of attack for corrosion and / or degradation of the layer are layer defects such as holes, pinholes or grain boundaries.

The invention has for its object to provide a method for coating a substrate, a coating for a substrate and a sliding element, in particular with such a coating, wherein said disadvantages do not occur.

The object is achieved by providing the subject matters of the independent claims. Advantageous embodiments emerge from the subclaims.

The object is achieved in particular by providing a method for coating a substrate, in which a first layer of amorphous carbon is arranged on the substrate. Nanoparticles are arranged on the first layer. Nanoparticles in particular have the property of collecting at defect sites, in particular grain boundaries, holes, microcracks, line defects, pinholes, or the like, which is also referred to as nucleation. In this way, the nanoparticles provide protection there for the first layer, where it is particularly exposed to corrosion and / or degradation effects. The nanoparticles on the first layer can thus help to protect the first layer against corrosion and / or degradation and thus also increased wear - especially in a motor oil-containing environment. At the same time, the favorable properties of the first amorphous carbon layer with respect to friction reduction and wear protection are maintained.

Under amorphous carbon is in particular DLC (Diamond-like carbon) understood. The first layer is thus designed in particular as a DLC coating. DLC is an amorphous, diamond-like carbon modification characterized by special properties such as high resistance to abrasive and adhesive wear, protection against surface disruption, chemical stability, good thermal conductivity and mechanical properties, in particular a high hardness and a high modulus of elasticity. distinguished. High hardness is obtained especially for DLC layer systems with a high proportion of sp ³ -hybridized carbon atoms, the mole fraction is more than 60%. This substance is also called tetrahedral bound amorphous carbon (ta-C). In addition, however, DLC layers are used which have a lower proportion of sp ³ -hybridized carbon atoms and are less hard than the ta-C layer systems, such as hydrogen-containing and / or metal-containing DLC systems.

The first layer is preferably deposited by chemical vapor deposition (CVD), Plasma Assisted Chemical Vapor Deposition (PACVD), Physical Vapor Deposition (PVDD), or atomic layer deposition (ALD) Substrate applied. The first layer is preferably applied with a layer thickness of at least 0.2 μm to at most 15 μm, preferably of at least 0.5 μm to at most 10 μm. In particular, the first layer ensures high hardness and a low coefficient of friction.

A nanoparticle is understood as meaning in particular an atom or molecular structure, in particular a cluster, a crystal, a quasicrystal, or the like, which has dimensions on the nanometer scale. In particular, the dimensions of such particles on the nanometer scale result in properties which are intrinsic to neither the individual atoms and / or molecules nor the corresponding bulk material.

Nanoparticles which comprise a noble metal, in particular gold, platinum, palladium or ruthenium, or which consist of a noble metal, in particular of noble metal atoms, preferably gold, platinum, palladium or ruthenium, are preferably arranged on the first layer. The nanoparticles can by physical vapor deposition, chemical vapor deposition, soft landing (Soff landing), or means wet chemical methods are produced. Nanoparticles having a size of at least 0.2 nm to at most 700 nm, preferably from at least 0.5 nm to at most 500 nm, are preferably arranged on the first layer. The nanoparticles are used in particular for the corrosion protection of the first layer, in particular by being deposited in the region of layer defects, in particular nucleating there, wherein they provide effective corrosion protection for the first layer especially at particularly vulnerable sites.

According to one embodiment of the invention, it is provided that a second layer is applied as a protective layer on the nanoparticles. In this case, it is possible in particular for the nanoparticles to be embedded in the second protective layer. This protective layer acts together with the nanoparticles quasi-sealing on the layer defects of the first layer and thus leads to a particularly efficient corrosion and / or degradation protection.

Preferably, a chemical-resistant protective layer is applied to the nanoparticles, wherein the protective layer is preferably inert to engine oil and in particular to components of engine oil. In this case, the protective layer itself does not react with the engine oil and prevents - together with the nanoparticles - at the same time that the engine oil or its constituents reach defects of the first layer and corrode or degrade there.

Preferably, a protective layer is applied to the nanoparticles, which comprises CrN, TiN, Al ₂ O ₃ and / or TaO _x , or consists of one of said materials. The second layer is preferably applied with a thickness of at least 0.1 nm to at most 100 nm, particularly preferably with a thickness of at least 0.2 nm to at most 50 nm.

According to one embodiment of the invention, it is provided that an adhesive layer is arranged between the substrate and the first layer. The adhesive layer mediates between the substrate and the first layer and in particular improves the adhesion of the first layer to the substrate. Preferably, an adhesive layer is used which comprises chromium or CrN, or consists of chromium or CrN. The adhesive layer may be made by chemical vapor deposition, plasma assisted chemical vapor deposition, physical vapor deposition, and / or atomic layer deposition.

Alternatively, it is also possible for the first layer to be applied directly to the substrate, in particular without an adhesive layer arranged therebetween.

According to one embodiment of the invention, it is provided that a layer is applied as the first layer, which has hydrogen. Alternatively or additionally, it is possible for the first layer to be doped with at least one metal. Alternatively or additionally, it is possible that the first layer is doped with at least one non-metal. In particular, the first layer formed as a DLC coating may have hydrogen and correspond to the type a-C: H. However, the first layer may also comprise a metal and be of the type a-C: H: Me, where Me is a metal which is preferably selected from a group consisting of chromium, tungsten and titanium. The first layer may also have hydrogen and be of the ta-C: H type. The first layer may also be doped with a nonmetal and of the type aC: H: X, where X is a nonmetal, which is preferably selected from a group consisting of silicon, oxygen, nitrogen and boron. Alternatively, it is also possible the first layer is a DLC coating which is hydrogen-free and type ta-C or type aC.

It thus turns out that the first layer can be produced with different hydrogen contents and / or different metal dopings.

According to one embodiment of the invention, it is provided that the first layer is produced from a layer. In particular, the first layer may consist of a single layer and preferably be prepared in a single coating cycle.

Alternatively, it is possible that the first layer is made of a plurality of layers. In particular, the first layer may then have a plurality of layers and / or be produced in a plurality of coating cycles.

According to a development of the invention, it is provided that the second layer, ie the protective layer, is produced by means of atomic layer deposition. With this method, it is possible to produce particularly low-defect, in particular hole-free, layers, which has proven itself in combination with a first layer designed as a DLC coating. The second layer can namely effectively protect the first layer from corrosion and / or degradation because, in particular together with the nanoparticles, it seals its defects and thereby itself is designed to be virtually defect-free or defect-free.

The object is also achieved by providing a coating for a substrate which has a first layer of amorphous carbon which is intended for the substrate and a plurality of layers arranged on the first layer Having nanoparticles. In connection with the coating, in particular, the advantages that have already been explained in connection with the method. Preferably, the coating is obtainable or manufactured by one of the previously described embodiments of the method. The fact that the first layer of amorphous carbon, which is preferably designed as a DLC coating, is intended to face the substrate means in particular that it is arranged on the substrate, namely either directly on a substrate surface, or mediated by at least one adhesive layer.

It is preferably provided that a second layer is arranged as a protective layer on the nanoparticles.

The object is also achieved by a sliding element is provided, wherein on a sliding surface of the sliding element, with which the sliding member comes in contact with a sliding partner as intended, a coating according to one of the embodiments described above, or wherein the sliding surface by means of a method according to one of the embodiments described above is coated. In particular, the advantages which have already been explained in connection with the coating process and the coating are realized in connection with the sliding element.

The sliding element is, in particular, a sliding element for an internal combustion engine, wherein the sliding element is intended to slide with its sliding surface relative to the sliding partner.

Preferred embodiments of such a sliding element are a piston of an internal combustion engine, a piston ring for a piston of an internal combustion engine, a cylinder of an internal combustion engine, wherein the sliding surface is in particular a cylinder wall, and in particular a cylinder liner for a cylinder of an internal combustion engine, wherein the sliding surface in particular an inner wall of the cylinder liner is, on which purpose a piston or a piston ring slides.

Sliding elements, in particular for internal combustion engines, are typically exposed to lubricating oils, in particular engine oil, during operation, so that the advantages of the proposed method and of the proposed coating are realized in a special way.

The description of the method on the one hand and the coating and the sliding element on the other hand are to be understood as complementary to one another. Process steps which have been explained explicitly or implicitly in connection with the coating and / or the sliding element are preferably individually or combined with one another Steps of a preferred embodiment of the method. Features of the coating and / or of the sliding element, which have been explained explicitly or implicitly in connection with the method, are preferably individually or combined with one another features of an intended embodiment of the coating and / or the sliding element. The method is preferably characterized by at least one method step, which is due to at least one feature of a coating according to the invention or preferred embodiment of the coating and / or the sliding element. The coating and / or the sliding element is preferably characterized by at least one feature that is caused by at least one method step of a preferred embodiment of the method according to the invention or preferred embodiment.

The invention will be explained in more detail below with reference to the drawing. The single figure shows a schematic representation of an embodiment of a coating.

The single figure shows a schematic representation of an embodiment of a coating 1 on a substrate 3 is arranged. This shows the coating 1 a first, the substrate 3 facing layer 5 of amorphous carbon, wherein the first layer 5 is designed in particular as a DLC coating. The layer thickness of the first layer 5 is preferably in the range of 0.5 .mu.m to 10 .mu.m. On the first layer 5 are a plurality of nanoparticles 7 arranged here, for the sake of clarity here only one of the nanoparticles 7 is provided with a reference numeral. The nanoparticles 7 nucleate especially at defect sites of the first layer 5 , especially at grain boundaries, holes, microcracks, line defects, pinholes, or the like. As a result, the nanoparticles provide 7 for the first shift 5 a corrosion and / or degradation protection.

On the nanoparticles 7 is a second layer 9 arranged as a protective layer, wherein the nanoparticles 7 especially in the second layer 9 are embedded. The second layer 9 can be made in particular by means of atomic layer deposition, so that it is very low defect, preferably formed defect-free. Thus, it seals together with the nanoparticles 7 Defects of the first layer 5 , and therefore can protect them in combination with the nanoparticles extremely efficient against corrosion and / or degradation.

Between the first shift 5 and the substrate 3 here is still an adhesive layer 11 arranged.

The substrate 3 is preferably designed as a sliding element, in particular for an internal combustion engine, wherein it can be designed especially as a piston, a piston ring, a cylinder or a cylinder liner for an internal combustion engine.

The first layer may comprise hydrogen, in particular with different proportions, and / or be doped with at least one metal or with at least one non-metal. Additionally or alternatively, the first layer may be made of one layer or of a plurality of layers.

Possible production methods for the first layer are CVD, PACVD, PVD and / or ALD. As an alternative to the embodiment illustrated here, it is also possible that the first layer directly on the substrate 3 is arranged.

The nanoparticles 7 are preferably made of gold, platinum, palladium and / or ruthenium. They can be made by PVD, CVD, gentle deposition, or by a wet chemical process. The particle size is preferably in the range of 0.5 nm to 500 nm.

The protective layer is preferably made of CrN, TiN, Al ₂ O ₃ , and / or TaO _x . The thickness of the second layer 9 , ie the protective layer, is preferably in the range of 0.2 nm to 50 nm.

The adhesive layer 11 For example, it may be chromium or CrN or it may be one of these materials. It may in particular be produced by means of CVD, PACVD, PVD and / or ALD.

Overall, it is found that a hard and at the same time corrosion-resistant tribological coating, in particular for use in an internal combustion engine, can be provided by means of the method, the coating and the sliding element described here.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been 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.

Cited patent literature

• EP 2574685 A1 [0002]

Claims (10)

Process for coating a substrate ( 3 ), wherein - on the substrate ( 3 ) a first layer ( 5 ) is arranged from amorphous carbon, and wherein - on the first layer ( 5 ) Nanoparticles ( 7 ) to be ordered. Method according to claim 1, characterized in that the nanoparticles ( 7 ) a second layer ( 9 ) is applied as a protective layer. Method according to one of the preceding claims, characterized in that between the substrate ( 3 ) and the first layer ( 5 ) an adhesive layer ( 11 ) is arranged. Method according to one of the preceding claims, characterized in that the first layer ( 5 ) Has hydrogen and / or is doped with at least one metal or at least one non-metal. Method according to one of the preceding claims, characterized in that the first layer ( 5 ) is produced from one layer or from a plurality of layers. Method according to one of the preceding claims, characterized in that the second layer ( 9 ) is produced by atomic layer deposition. Coating ( 1 ) for a substrate ( 3 ), with - a first, the substrate ( 3 ) intended facing layer ( 5 ) of amorphous carbon, and with - one on the first layer ( 5 ) arranged plurality of nanoparticles ( 7 ). Coating ( 1 ) according to claim 7, characterized in that on the nanoparticles ( 7 ) a second layer ( 9 ) is arranged as a protective layer. Sliding element, in particular for an internal combustion engine, wherein on a sliding surface of the sliding element with which the sliding element comes into contact with a sliding partner as intended, a coating ( 1 ) according to one of claims 7 or 8, or wherein the sliding surface is coated by means of a method according to one of claims 1 to 6. Sliding element according to claim 9, characterized in that the sliding element is designed as a piston, as a piston ring, as a cylinder, or as a cylinder liner.

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