JP5669390B2 - Abrasion resistant coating and manufacturing method therefor - Google Patents

Description

  The present invention is in the field of tribology and deals with coatings on machine parts to reduce friction loss and wear. Basically, the present invention is applicable to a wide variety of machine parts that are subject to frictional wear. However, as a particularly advantageous example, it is cited for use in components of internal combustion engines, in particular in valve device parts such as bucket tappets. However, applications in industrial use are also conceivable, for example in rolling bearings and linear bearings.

  Basically, the requirements for such parts are further increased by increasing the mechanical load, the speed of movement and the pot life. At that time, even less maintenance management is assumed. Corresponding lubricants are increasingly demanding not to burden the environment, so that less additive is used and partly with low viscosity lubricants or even without lubricants. There is a tendency to drive.

  Not only liquid lubricated contact areas, but also dry contact areas and corresponding requirements for low friction and adhesion in contact areas, low adhesion, high wear resistance and at the same time toughness against impact loads and resistance to fracture The corresponding requirements are no longer met by conventional coatings.

  In part, each of the requirements can be met by a coating that is characterized in a particular way, for example hardness or slight frictional resistance, but other properties of the tribological system are detrimentally affected. .

  This is particularly evident in the example of a valve device in an internal combustion engine, with particular attention being paid to cam tappet devices.

  For example, such a cam tappet device is mounted in an automobile engine having a reciprocating piston having an intake valve and an exhaust valve that opens and closes at the stage of rotation of the crankshaft or in synchronization therewith. The valve drive mechanism is used to transmit the movement of a cam attached to the camshaft to the valve when the camshaft rotates together with the engine crankshaft. At that time, the cam of the cam shaft is brought into frictional contact with the sliding surface of the incorporated bucket tappet.

  In general, the demands placed on such valve device components such as bucket tappets and pump tappets are increasing. The reason why increased wear resistance is required is due to the increasing loads and stresses of the tribological system consisting of control cams and control tappets. This is due to new engine specifications, such as gasoline systems and direct injection diesel engine systems, with increasing injection pressures, an increased proportion of abrasive particles in the lubricant, insufficient oil supply to the friction partner (as a result With increased proportion of mixed friction), and increased use of tribologically disadvantageous steel cams for cost reduction and weight reduction. A significant contribution to resource conservation is a reduction in friction loss in the valve device, resulting in fuel savings and at the same time increasing the overall life of the valve device. In order to effectively reduce the friction loss, it is necessary to reduce the friction torque over a wide range of rotation speeds.

  It is known to form such bucket tappets for valve control of internal combustion engines as light alloy tappets, which are hardened surfaces inserted into the contact surfaces for the tappet body and the control cam of the valve control device With a steel plate.

  However, as a disadvantage of this attempt, it is clear that such bucket tappets are exposed to relatively large temperature fluctuations from −30 ° C. during cold start to about 130 ° C. during combustion engine operation in operating cases. became. The problem here is the various thermal expansions of the materials used. Indeed, steel plates inserted into light alloy tappets as inserts have good wear properties, however, they tend to delaminate under corresponding heat loads. Therefore, the heat load capacity is limited. Another disadvantage of the applied technology is the loss of structural space in the form of a relatively wide edge as a functional surface with which the control cam of the valve control device contacts or as a cam contact surface.

  According to the prior art, the sliding surfaces of machine parts that are subject to frictional wear, depending on the application, are preferably made of electroplated metal or applied in a spraying process, possibly hard It is likewise known to provide a wear protection layer consisting of a metal and / or metal alloy with the composition.

  However, in this case, the fact that the sprayed metal layer has a relatively weak intensity is manifested as a drawback, and therefore, for the improvement of the intensity, the metal layer can be treated with, for example, a plasma beam, a laser beam, an electron beam or an arc. It is known that after the application by, the spray material is melted so as to melt and mix with the base material melted in the surface region at the same time and form an alloy. In addition, in order to have good tribological properties, the sprayed and thus coarse coating must be mechanically post-processed. However, in the case of a molten alloy, non-uniform zones of various compositions that can occupy a large number of layer materials as well as the base material occur. If the proportion of the base material is too high, then the wear of the layer will be too high, and if the proportion of the base material is low, macro cracks may form during the combination of the various layers, so that Such a layer is not usable. In such cases, undesired adhesive wear can be caused in the layer by friction loading.

  Moreover, it is known to carbonitrid and / or soft-nitride the sliding surfaces of bucket tappets by a thermal process. However, in that case, a satisfactory coefficient of friction was not achieved, and it was revealed as a drawback that wear resistance that was too low occurred.

  In addition, it is known to coat the sliding surface of the tappet with a manganese phosphate layer or a slide coat (Gleitklack). Again, satisfactory coefficient of friction and wear resistance are not achieved. In addition, such a material places an extra burden on the environment. The same applies to electroplating layers that can be applied to the sliding surface as well.

  From the prior art, hard alloys and high-speed steel (ASP 23) are also known as coating materials, however, they are additionally high as disadvantages, besides an unsatisfactory coefficient of friction and unsatisfactory wear resistance. Have mass.

  In addition, hard, for example, PVD or (PA) CVD layers, such as TiN, CrN, (Ti, Al) N, are known. However, as a disadvantage of this attempt, these layers result in increased wear of the mating body if they are not post-processed. When post-processed, an indeterminate surface condition results based on the reactive surface.

  From US Pat. No. 5,237,967, carbon-based PVD and (PA) CVD layers with 20-60 atomic% hydrogen in the coating layer, so-called metal-containing hydrocarbon layers (aC: H: Me) and non- A crystalline hydrocarbon layer (aC: H) is known. However, because these layers have relatively low wear and fatigue resistance, they are not suitable for high load structural members in new generation engines and the friction reduction provided during operation is relatively small.

  As already explained above, the reduction of friction in the valve device necessarily contributes to fuel savings and resource conservation. This goal can be achieved by reducing the area of solid friction and mixed friction and thus increasing the area of liquid friction with complete material separation. This is achieved by the overall roughness optimized as much as possible of the tribological system consisting of bucket tappet and camshaft.

  In order to obtain the optimum surface structure of the bucket tappet required for this purpose over the entire life, the surface has a high wear resistance, a slight tendency to adhere to the mating body and a low reactivity to the surroundings. You need to form it. In addition, the surface should preferably not contain abrasive particles such as liquid particles.

  Bucket tappets from iron-carbon alloys do not reach the wear and tribologically advantageous surface conditions required for this even in heat treated states such as carbonitriding, soft nitriding or nitriding. For example, when the nitride layer is mechanically post-treated, in particular by (fine) grinding, lapping, polishing, light rays, etc., the chemical composition and the reactivity of the surface can be changed in addition to the surface structure. These changes are largely distributed on the one hand, so that uniform quality cannot be achieved. On the other hand, localized affine surfaces have more inconvenient tribological properties and tend to adhere to the mating body. Moreover, internal and compressive stresses are induced in the region near the surface by the grinding and polishing processes, which stresses are added to the high internal compressive stress of the hard composition layer already present.

  Additionally, the induced misalignment and torn liquid particles cause floatation and macrocracking, resulting in reduced local fatigue resistance of the layer in the bucket tappet and adhesive strength It goes down until it can break apart during post-processing.

  However, if, for example, in a layer deposited by the arc method, the subsequent polishing is omitted, the hard liquid particles randomly cause the abrasive wear of the counterpart body or at least the polish of the counterpart body, which is an unexpected disadvantage. Results. In addition, the liquid particles break up and exit the layer during operation, which results in damage to the layer and free particles that are abrasive.

In addition, from DE 102004043550A1, the wear-resistant coating has the function of at least one nanocrystal from at least two CrN _x phases for reducing friction and for increasing the wear resistance of the surface of a predetermined machine part. Forms consisting of layers are known. However, this coating also does not ideally meet all tribological requirements with regard to friction reduction and wear resistance, especially in the mixed friction region.

  The problem underlying the present invention is therefore a coating that eliminates the above-mentioned drawbacks and reduces the friction torque, especially over the entire service area, and increases the working time of the coated machine part and the mating body, and thus Is to provide a manufacturing method for a simple coating.

  This problem is solved according to the invention by a wear-resistant coating having the features of claim 1 and by a method having the features of claim 21.

  A nanostructured layer by having a functional layer based on hydrogen-containing carbon and in the cross-section having a range of various consistency (Konsistenz) that is less than 20 nm in a direction and less than 10 nm in one direction. Within the layer, regions of different consistency, i.e. regions from different materials, different transformations, for example, may be of a single homogeneous nature, either by different material proportions or simply by different crystal orientations. Depending on the material, it can meet various challenges that are very difficult to meet. However, due to the nanostructure, in the functional layer at the same time, different areas, for example for reducing sliding friction and for generating the required material hardness, are facing the friction partner.

  This is also true when the functional layer is formed at least partly by a layer essentially parallel to the surface forming the regions of different consistency. In this case, the slight thickness of the layer (<20 nm or even <10 nm) creates a hybrid surface where the various layers appear at different points already from the beginning or after a short run and after wear has begun. The surface of the functional layer thus provides the friction partner with different surface areas having different hardness, different friction properties, adhesion and different toughness. Such nanostructures additionally create high crack resistance to layer splitting and exfoliation due to inhomogeneities. With the appropriate configuration and arrangement of the layers, increased corrosion resistance or increased wettability or reduced wettability can be achieved with the lubricant. Measurements have shown that a 30% reduction in friction torque as well as a 15-70 GP hardness reduction can be achieved with the present invention.

  Advantageously, in such a form, one or more of the layers are thinner than 10 nm. In so doing, typically the number of layers is more than two and can be up to several tens, in particular more than 50 or 100, so that the total thickness of the layers can be up to 10 micrometers.

  In that case, the adjacent layers have different consistency each time, for example in that at least two adjacent layers have different next three consistency each time. Amorphous, metal-free, hydrogen-containing carbon, amorphous, metal-containing, hydrogen-containing carbon, amorphous, at least one non-metal-containing, hydrogen-containing carbon. In so doing, it may contain essentially less than 1% of processed impurities.

  In addition, a layer with other properties may be provided. In doing so, hydrogen-containing carbon containing non-metals, for example, typically has the property of reducing frictional forces, and, for example, when fluorine, silicon or oxygen is incorporated, it promotes slight wetting by the lubricant. Also have. Thereby, a thinner oil film is encouraged, which is advantageous for the friction partner, for example in the valve device, especially when the relative movement is fast.

  Metal-containing amorphous hydrogen-containing hydrocarbons typically have rather properties of hardness and friction strength.

  The distinction between adjacent layers can also be made simply by being doped with different materials or by different amounts of doping.

  Especially when it is in the crystalline phase, the material properties are obviously changed by doping. Doping can therefore be used to generate specific mechanical properties for the purpose, the properties produced thereby also depending on the type and size of the doping atoms. In addition, the type of crystal structure that is generated depends on the amount of doping atoms in that the crystal transition takes place from a certain doping level or in that the mixed phase results from various transformations. Thus, adjacent layers that are distinguished only by the type or amount of doping also have completely different mechanical or tribological properties.

  In addition, adjacent layers can also be distinguished by hydrogen expressed as a percentage in amorphous carbon. The proportion of hydrogen in the carbon also clearly determines basic tribological properties. If the hydrogen proportion is lower than 20%, in particular 5% to 20%, the hydrogen-containing amorphous carbon tends to be harder, which proportion is advantageous for the implementation according to the invention.

The percentage ratio of sp ³ -and sp ² -hybrid orbital carbons can also distinguish two adjacent layers from each other. This relates to carbon existing in the form of diamond- and graphite transformations with various mechanical properties as is known. Accordingly, such various adjacent layers also have various tribological properties. In this case, it is particularly advantageous when the proportion of sp ³ -hybrid orbital C atoms is greater than 50% of C atoms.

It may also be advantageously planned that at least one of the parameters: hydrogen content, proportion of sp ³ -hybrid orbital C atoms, doping in at least one layer has a gradient perpendicular to the surface of the coating.

  In that case, it is particularly important to provide different areas with different mechanical properties on the actual friction surface in substantial use.

  Depending on the described type and form of the layers and on the thickness and sequence of the layers as viewed from the friction surface, the quality of the surface increases with the high hardness, It can be continually adjusted by the fact that the proportion of the area with great toughness or effective friction reduction occupies the majority or less. Thus, the present invention allows for individual tailoring to the customer's special requirements by suitable stratification of regions having different consistency.

  It may also be envisaged according to the invention that the region is at least partly formed by nanoparticles. These may be formed, for example, from one or more of the following materials: nitrides, borides, carbides, silicides. In this case, for example, chromium nitride, titanium nitride, silicon nitride, silicon carbide or titanium carbide can be considered.

  Such nanoparticles may be deposited together with the corresponding hydrogen-containing carbon layer, or before or after the deposition, for example, within the framework of the deposition process.

  For this purpose, sometimes the correspondingly required substances are entrained in the gas phase in the deposition apparatus, promoting the crystallization of the particles by either sputtering or other known methods and by the processing parameters. In this case, nano-dispersed self-assembled regions are generated from various crystals or from crystals of the same structure having various orientations thereto.

  For example, so-called nitride formers, such as chromium, titanium, and other elements that form unstable nitrides, such as copper, may be deposited together, for example when copper and chromium nitride are used, copper The proportion may be less than 2% with respect to the chromium proportion. Chromium nitride is then formed as nanocrystals in the copper matrix. Similar results can be achieved with titanium nitride and a very small proportion of boron, in which case titanium carbide can be used instead of titanium nitride, in which case the corresponding nitride or carbide is quasi-amorphous. Crystallize in a boron matrix.

  As a result, the corresponding nanoparticles can be embedded in an amorphous layer of hydrogen-containing carbon, or a nanoparticle layer can be formed between the carbon layers.

  In that case, it is important that the formed layer is thin or that the particles are finely dispersed, and as a result, the area of the exposed nanoparticles on the surface of the functional layer only occupies a part of the surface. Instead, the other parts will be covered by regions of other consistency having other mechanical or tribological properties.

  The introduction of nanoparticles also effectively prevents overall crack propagation in the resulting functional layer, in addition to their inherent mechanical properties. This is ensured in an optimal manner for nanoparticle sizes of less than 20 nm and better than 10 nm.

  Advantageously, the coating has at least one adhesion promoting layer made of chromium, tungsten or titanium or of a transition metal boride, carbide or nitride under the functional layer. Such an adhesion promoter stabilizes the entire structure from the coated machine part having the functional layer and in particular prevents the separation of the functional layer. As materials suitable for machine parts, the usual easy to process and low cost materials (16MnCr5, C45, 100Cr6, 31CrMoV9, 80Cr2, etc.) are taken into account. As a friction partner, an iron / carbon alloy can also be considered in order to reduce weight in the sense of a lightweight structure.

  In addition, it is particularly advantageous to provide a support layer underneath a functional layer from a metal-containing or non-metal-containing hydrogen-containing carbon layer, which layer on the one hand contains the components tungsten, tantalum, chromium. , Vanadium, hafnium, titanium or nickel or on the other hand one or more of silicon, oxygen, fluorine, nitrogen.

  Such a support layer interrupts the load of large mechanical forces acting on the functional layer, so that the functional layer can be destroyed by separation or crack formation and splitting of the base layer (Untergruende). Has the problem of preventing excessive deformation. The intermediate layer is remarkably fixed, in which case it does not have to have frictional resistance or wear strength. The support layer is therefore tailored to suit the purpose so that it has a slight plasticity or in terms of the plasticity it creates an optimal transition between the functional layer and the actual mechanical member It may be configured in the form.

  Furthermore, the present invention relates to a method for producing a coating according to claim 1 and below, in order to apply the region on the surface in the deposition method, the processing parameters are determined by the size of the region formed by the deposition. You may change at the time of continuing so that it may be less than 20 nm in the cross section. Particularly advantageous is when the region size is below 10 nm.

  For this purpose, at least one of the parameters pressure, temperature, doping substance incorporation, hydrogen content, rotational speed, carbon content may be varied irregularly or continuously during the production of the functional layer.

  As in the case of the deposition process, the processing temperature of 250 ° C. is advantageously not exceeded in the case of other coating steps which may be possible depending on the situation, for example baking or plasma etching. This is because it keeps the hardness of the base material of the machine part, and does not have to be post-processed, for example by induction hardening.

  The deposition takes place within the framework of the known PVD (physical vapor deposition) and (PA) CVD (plasma assisted chemical vapor deposition) methods.

  In the case of PVD methods, the starting material, for example graphite, is heated in a manner that is accelerated in a section in the direction of the surface to be coated, where the beam of high-energy carbon ions from the graphite is imitated.

  In the case of (PA) CVD methods, with the aid of plasma, a gas mixture is introduced into the process chamber in which the material parts to be coated are present. The (PA) CVD method is an advanced form of the CVD method, and combines the advantages of the CVO method (omnidirectional processing) and the PVD method (low temperature). In the case of the PACVD method, the layer deposition is performed by a chemical reaction from the gas phase at a temperature below 200 ° C. that is plasma-supported for the purpose.

  Changes in the processing parameters such as pressure, temperature and hydrogen content and the rotational speed of the doping substance or the object to be coated determine the structure of the resulting coating. In so doing, at certain parameter limits, irregular changes in the consistency of the deposited layer also occur. This is because certain, in particular crystalline arrangements, can only be formed up to a certain material proportion of the individual substances. In the absence of these moieties, other crystals or other transformations or mixed phases are formed.

  Thus, by changing the processing parameters, correspondingly small (less than 10 nm) regions can be deposited in particles or layers at suitable time intervals.

  The present invention finally relates to a valve tappet for a valve of an internal combustion engine operable by a mechanical member, in particular a cam, provided with a coating according to the invention.

  In the following, the present invention will be illustrated and explained with reference to an embodiment for taking out the valve tappet as a reference.

The figure which shows the front of the friction couple which consists of the bucket tappet and the camshaft for operating the valve of the combustion engine Figure showing a perspective view of the bucket tappet from Figure 1 Figure showing a perspective view of a hydraulic support element (hydraulisches Abstuetzelement) connected to a drag lever via a rolling bearing part 1 shows a schematic cross section of a mechanical member having an abrasion resistant coating according to an embodiment of the present invention. Diagram showing functional layer

  In the drawings, the same reference number represents the same part or the same part in function unless otherwise stated.

  FIG. 1 illustrates a friction pair consisting of a bucket tappet 5 having a cam contact surface 50 and a bucket shirt 51 and a cam 6. The bucket tappet 5 is shown in detail in the form of a perspective in FIG. In general, the bucket tappet 5 is connected to a valve shaft 7 for a material part in a combustion engine, which opens the valve by sliding the cam surface towards the cam contact surface 50 of the bucket tappet 5 or close up.

  In general, state-of-the-art valve device components, for example bucket tappets and pump tappets, impose high demands on the contact surface 50 in particular in terms of wear resistance and resource conservation.

  In connection with FIG. 4 illustrating a schematic cross-sectional view of a wear-resistant coating for a mechanical member 1, for example a bucket tappet 5, according to an advantageous embodiment of the invention, an embodiment of the invention is described. This will be described in detail below.

  The packet tappet 5 is used in the region of the cam contact surface 50 or in the region of the cam contact surface 50 and the bucket shirt 51 as necessary to reduce the coefficient of friction and increase wear resistance. Coated with an abrasion resistant coating according to the invention. When the deformation of the bucket shirt 51 of the bucket tappet 50 in the exposed region is strong, the bucket shirt 51 may be partially coated selectively.

  The surface 2 to be coated, ie here the cam contact surface 50 of the bucket tappet 5, is preferably surface hardened or carbonitrided and tempered before coating.

  The cam contact surface 50 of the body in this case, preferably a bucket tappet 5 made of low-cost steel material, for example 16MnCr5, C45, 100Cr6, 31CrMoV9, 80Cr2, etc., is first coated with the adhesion promoting layer 3 according to this embodiment. . The adhesion-promoting layer 3 consists of a compound from, for example, metal-containing carbon, for example tungsten and carbon, but also from metal materials (for example Cr, Ti), and transition metal borides, carbides, nitrides and silicides. It's okay. Additional support layers above the adhesion promoting layer can be metallic or non-metallic, such as W, Ta, Cr, V, Hf, Ti, Ni or Si, O, F, N and amorphous carbon containing hydrogen. Consists of. The adhesion-promoting layer and the support layer are associated with heat treatments such as surface hardening, carbonitriding, soft nitriding, by thermochemical methods such as nitriding, boriding, by galvanic methods, for example by applying chromium-containing layers, or It can be formed by application of methods such as Me-C, transition metal carbides and nitrides.

  The fatigue strength of the entire coating should be increased by the support layer, i.e. plastic deformation, crack formation, crack growth and rupture of the layer system should be prevented. Such fatigue processes can occur due to cam loading and the material stress of the bucket tappet 5 caused therefrom, as well as various hardness levels, elastic moduli and plasticity of the individual layers or bodies and wear-resistant coatings. In this case, the formation of layer 3 as support layer 3 is preferred either alone or in combination with a suitable adhesion promoting layer.

  As shown in FIG. 4, an abrasion resistant coating 4 is formed on the support layer and / or adhesion promoting layer 3 according to this embodiment.

  The functional layer 4 is then shown schematically as being composed of four individual nanolayers, in which the size ratio is reproduced only graphically and not to scale.

  On the other hand, in FIG. 5, the functional layer is shown clearly enlarged on a scale. The left half of the figure then shows a variant with several layers of sub-10 nm thick layers of amorphous carbon containing hydrogen, each with a different consistency. On the other hand, on the right side of the figure, an alternative with additional nanodispersed particles is shown.

  The scale is further expanded in a direction perpendicular to the surface because of the small thickness of the nanolayer. The corrugated line on the surface represents the actual surface, which is naturally adjusted during manufacture or after use. This waveform is not as large as actually shown, but rather appears to be emphasized perpendicular to the friction surface by a uniaxial enlargement of scale. Nevertheless, the effect achieved by the present invention can be explained using this figure as a clue. The individual layers 60, 61, 62 are variously thinly drawn toward the surface in at least the upper region and are distinguishable thereby. Due to the structure of some irregular surfaces (several nanometers), the lower layers 61, 62 and also the individual below them were not marked at various points after the first start-up and after wear at the latest. It becomes clear that a layer appears. These layers each have different tribological properties, so that the surface of the friction partner as a mixture of very different areas with different properties in terms of hardness, elasticity, wear resistance and coefficient of friction. The whole appears. This condition will continue to be maintained as wear increases further, but this is greatly postponed by the structure described and the adjusted wear resistance.

  The individual layers are distinguished at least in part by referring to the consistency, i.e. the hydrogen proportion, the type and amount of doped material or crystal transformation added and the orientation. At the same time, a few layers or multiple layers are exposed on the surface.

  On the right side of FIG. 5, a deformation is shown in which the nanoparticles 63, 64 are introduced together in the carbon matrix. Corresponding nanoparticles, which may be formed, for example, as borides, carbides or nitrides, form hard and wear-resistant regions where they appear on the surface, ie in the case of particles 63, 64 and thus Abrasion of the carbon matrix material surrounding the particles is also prevented. This also contributes somewhat to the reduction of the coefficient of friction, for example, depending on the surface composition.

  If some material is scraped off the surface of the functional layer in the process of wear, new nanoparticles will appear, and then the particles will again be responsible for the listed issues of ensuring hardness and wear resistance.

  In principle, the nanoparticles may be concentrated in different layers. This is the case, for example, when certain metal nitrides, metal borides or metal carbides that are deposited in a mixture ratio that automatically forms different phases between the deposits of the other layers are used throughout the PVD or PACVD process. It can be considered within the framework of the deposition process by being introduced. This then forms hard nanoparticles in the corresponding layer.

  The described invention creates a new coating that allows the adaptation of the tribological requirements to this very precise form by the choice of particles and individual nanolayers, with known homogeneous materials The parameters can be adjusted in the macro region by mixing regions with different consistency on the surface that cannot be achieved. In addition, the present invention provides a simple manufacturing method for such functional layers that does not require structural changes during PVD and (PA) CVD-coating compared to previously used manufacturing means. To do.

  The maximum coating temperature is preferably 250 ° C. so that the base material is not tempered during the coating process.

  The coating is formed with a thickness of about 0.5 μm to about 10.0 μm, preferably 2.0 μm. Thereby, the dimensions and surface roughness of the body change only so little that no post-processing is required.

  In the following, further advantageous uses of the coating according to the invention will be described in detail. FIG. 3 shows a perspective view of a hydraulic support element 8 having a piston 9 and a casing 10. The hydraulic support element 8 is connected to a drag lever 11, and at this time, the drag lever 11 is pivotable via a rolling bearing 12. Moreover, as can be seen in FIG. 3, the piston 9 has a contact area 90 between the piston 9 and the drag lever 11. In addition, the piston 9 has a contact area 91 between the piston 9 and the casing 10. In order to reduce the wear in the contact area 90 between the piston 9 and the drag lever 11, the contact area 90 is likewise provided with a nanostructured functional layer 4 according to the invention.

  Moreover, the contact area 91 between the piston 9 and the casing 10 can likewise be coated with such a coating 3, 4 depending on the application and the manufacturing technique. Thereby, the overall lifetime of the represented tribology system is increased, thereby reducing the failure of individual machine parts during operation and thus overall cost savings.

  In addition to this, the rolling bearing 12, such as rolling element parts, inner and outer races of the rolling bearing 12, rolling bearing cages, disks, etc., are simultaneously used for increasing the wear resistance and friction by the functional layer 4 according to the invention. For reduction, for example, it may be coated under the intermediate connection of the support layer and / or the adhesion promoting layer 3.

  Of course, the above-mentioned layer system is used for other structural and functional units, such as valve stems, support elements and plug-in units, rolling bearing parts, release bearings, piston pins, bearing bushes, for example injection nozzles in the engine area. It is also suitable for other control pistons, linear bearings and other parts that are subjected to high mechanical and tribological loads.

  It is pointed out at this point that the functional layer 4 can also be deposited directly on the body of the machine part to be coated without applying a support layer 3 or an adhesion promoting layer 3 therebetween.

  Although the invention has been described above with reference to advantageous embodiments, it is not limited thereto but rather can be modified in a wide variety of ways.

  DESCRIPTION OF SYMBOLS 1 Machine member 2 Predetermined machine member surface 3 Support layer / adhesion promotion layer 4 Nanocrystal functional layer 5 Bucket tappet 6 Cam 7 Valve stem 8 Hydraulic support element 9 Piston 10 Casing 11 Drag lever, 12 Rolling bearing, 50 Cam contact surface, 51 Bucket shirt, 60 layers, 61 layers, 62 layers, 63 nanoparticles, 64 nanoparticles, 90 Contact area between piston and drag lever, 91 Piston and casing Contact area between

Claims (19)

A wear-resistant coating having a functional layer based on hydrogenated amorphous carbon for equipment parts exposed to frictional wear, wherein the functional layer is selected from hydrogenated amorphous carbon layers having different consistency. Wherein the uppermost layer is a non-metal-containing hydrogenated amorphous carbon layer, the non-metal comprising fluorine, silicon and / or oxygen, and the region (60, 61, 62) . 61, 62) each having a layer thickness of less than 20 nm and at least partly formed from nanoparticles of one or more of nitrides, borides, carbides and silicides (63, 64) ) Are embedded in at least one hydrogenated amorphous carbon layer of the region (60, 61, 62) or the region And wherein the forming the nanoparticle layer in hydrogenated amorphous carbon layers of (60, 61, 62), abrasion resistant coatings for aircraft members.   2. Coating according to claim 1, characterized in that the region (60, 61, 62, 63, 64) is at least partly formed by a layer parallel to the coating surface.   Coating according to claim 1 or 2, characterized in that the thickness of at least one of the regions (60, 61, 62) is less than 10 nm.   At least two of the adjacent regions (60, 61, 62) have a metal-free hydrogenated amorphous carbon layer, a metal-containing hydrogenated amorphous carbon layer, or a non-metal-containing metal-free hydrogenated amorphous, each having a different consistency. 4. Coating according to any one of claims 1 to 3, characterized in that it is selected from carbon layers.   Coating according to any one of claims 1 to 4, characterized in that adjacent regions (60, 61, 62) are distinguished by the type and / or amount of doping.   6. Coating according to any one of claims 1 to 5, characterized in that adjacent regions (60, 61, 62) are distinguished by a hydrogen fraction expressed as a percentage. Coating according to any one of claims 1 to 6, characterized in that adjacent regions (60, 61, 62) are distinguished by the quantity ratio of sp ³ -and sp ² -hybrid orbital carbon. At least one of the parameters in at least one of the regions (60, 61, 62): hydrogen content, proportion of sp ³ -orbital C atoms, at least one of the dopings has a gradient perpendicular to the surface of the coating, 8. A coating according to any one of claims 1-7.   9. Coating according to claim 1, wherein the regions (63, 64) of the same composition are provided with different crystal orientations.   10. Coating according to any one of claims 1 to 9, characterized in that the regions (63, 64) are made of nanocrystalline material.   Under the functional layer, there is provided at least one adhesion promoting layer made of chromium, tungsten or titanium, or made of transition metal boride, carbide, nitride or silicide. Item 11. The coating according to any one of Items 1 to 10.   Under the functional layer, a support layer made of a metal layer containing hydrogen or a metal-containing or non-metal is provided, and the support layer is made of tungsten, tantalum, chromium, vanadium, hafnium, titanium and nickel as metals. It contains one or more components selected from the group consisting of or one or more components selected from the group consisting of silicon, oxygen, fluorine and nitrogen as non-metals. 12. The coating according to any one of 1 to 11.   13. Coating according to any one of claims 1 to 12, characterized in that the layer thickness of the functional layer is between 0.5 and 10 micrometers.   14. A coating according to any one of the preceding claims, characterized in that the hydrogenated amorphous carbon layer contains less than 20 atomic percent of hydrogen. 15. A method for producing a coating as claimed in any one of claims 1 to 14, wherein the regions (60, 61, 62) are each less than 20 nm in thickness on the material component by PVD or (PA) CVD. The method is characterized in that at least one of the processing parameters consisting of pressure, temperature, doping material incorporation, hydrogen content and rotational speed is changed at regular time intervals so as to deposit at   16. Method according to claim 15, characterized in that the processing parameters are controlled so that each layer thickness of the region (60, 61, 62) is deposited below 10 nm respectively.   17. The process according to claim 15 or 16, characterized in that at least one of the processing parameters consisting of pressure, temperature, doping substance incorporation, hydrogen content and rotational speed is irregularly changed many times during the production of the functional layer. the method of.   18. Process according to any one of claims 15 to 17, characterized in that the production of the coating is carried out at a temperature below 250 [deg.] C.   15. A valve tappet for a valve of an internal combustion engine operable by a cam, comprising a coating according to any one of claims 1-14.

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