Coating cylinder performents without pre-

Abstract

The invention relates to the coating of cylinder perforations without a pre-activated surface, to a cylinder of a piston internal combustion engine, comprising at least one perforation having an inner shell formed from a substrate material, in the region of which the substrate material is at least partially provided with a layer system, and thereby a first interface is formed between the substrate material and the layer system, and the layer system comprises at least one thermally sprayed layer, and the thermally sprayed layer at least partially forms the perforated shell surface and can be used there as a functional layer, and wherein the first interface does not include a profile applied for mechanically activating the surface except for the surface roughness resulting from the manufacture of the perforation. The invention is characterized in that the material of the layer system contains molybdenum and a further element in the interface region with the substrate material, also referred to as the interface material, and is bonded to the substrate material by chemical bonding, the interface material being different from the material of the functional layer in terms of its composition and / or structure.

Description

[0001] This application is a divisional application of patent application No. 201780043504.3, filed on July 13, 2017, entitled "Coating cylinder perforations without pre-activation of the surface". Technical Field

[0002] The cylinder perforations of some piston-type internal combustion engines are typically coated with a thermal spray to minimize weight and / or friction and / or wear. This reduces fuel and oil consumption and preferably also makes the surface of the cylinder perforation more corrosion-resistant.

[0003] However, adhesion of this layer to the cylinder material is problematic, thus posing a risk of peeling during operation. To improve it to the level required for the application, the perforated surfaces of the cylinder are typically roughened (activated). This activation ensures a mechanical interlock between the layer and the base material of the cylinder body, i.e., shape locking. This pre-processing step of activating the cylinder operating surfaces increases the cost of the coating. Background Technology

[0004] The interlacing between the cylinder block layer and the base material achieved through activation improves the adhesion of the layer to the base material and contributes to a longer cylinder service life. Activation can be performed using various techniques. For example, the surface can be roughened by corundum blasting, laser blasting, high-pressure water blasting, and / or low-pressure water blasting. Another possibility for activation is to provide the surface with a profile with a backcut, for example, by machining. Dovetail geometry is advantageously used here, for example.

[0005] Accordingly, Figure 1 The image shows that the sprayed coating 3 and the substrate material 1 are mechanically interlocked by activating the substrate material prior to coating. According to the prior art, this improves adhesion to the substrate material 1, for example, a cylinder perforation.

[0006] The main drawback of the above activation methods is that they can only be achieved by increasing production costs. In addition to the increased processing time required for the additional steps, there are also additional investment costs for the tools and / or machines used for activation.

[0007] Early attempts have attempted to avoid surface activation using an interlayer. For example, Shepard disclosed a molybdenum layer as an interlayer in US 2588422. It forms interfaces with the substrate material on one side and with the sprayed functional layer on the other. Besides the fact that elemental molybdenum is a very soft material, this approach also suffers from the problem that it does not necessarily improve adhesion at the two interfaces in a satisfactory manner. Summary of the Invention

[0008] Therefore, the object of the present invention is to provide a method for adhesively applying a thermally sprayed coating to a cylinder perforated shell without requiring the activation, particularly mechanical activation, that is typically required for the surface to be coated.

[0009] According to the invention, the objective is achieved by the cylinder of the invention according to claim 1 and the method of the invention according to claim 8. Claims 2 to 7 and 9 to 12 relate to further advantageous embodiments of the invention, and claims 13 and 14 relate to the corresponding engine or its manufacture.

[0010] The cylinder includes at least one perforation having an inner shell formed of a base material, wherein the base material is at least partially provided with a layer system in the region of the perforation. This forms a first interface between the base material and the layer system, wherein the first interface, apart from the surface roughness resulting from the fabrication of the perforation, does not include contours applied for surface activation, particularly contours applied for mechanical surface activation.

[0011] The layer system includes at least one thermally sprayed layer, particularly a layer thermally sprayed by means of plasma spraying, preferably a layer thermally sprayed by means of a rotating plasma burner, and the thermally sprayed layer at least partially forms the perforated shell surface and can be used there as a functional layer. Hereinafter, "functional layer" may also be preferably understood as a layer with functions, and particularly preferably as a thermally sprayed functional layer.

[0012] The core of this method is to apply an adhesive layer directly to the base material of the cylinder perforated shell, thereby forming at least a chemical bond between the adhesive layer and the base material. The adhesive layer may contain an interface material, and in particular, be composed of an interface material. Thus, adhesion at the interface with the base material is not primarily achieved through mechanical interlocking, but rather primarily through chemical bonding.

[0013] The interface material comprises molybdenum (Mo) and at least one other element, but in particular, it may consist essentially of molybdenum and at least one other element. If the presence of another element is mentioned in this specification or claims, it may, but is not required to, exist in elemental form, but may also exist as a molecule and / or in a compound.

[0014] In one embodiment of the invention, the proportion of molybdenum in the interface material, particularly in the adhesive layer, can be 30 to 90% by weight, and the proportion of other elements in the interface material, particularly in the adhesive layer, can be 70 to 10% by weight; preferably, the proportion of molybdenum in the interface material can be 40 to 80% by weight, and the proportion of other elements in the interface material can be 60 to 20% by weight; particularly preferably, the proportion of molybdenum in the interface material can be 50 to 70% by weight, and the proportion of other elements in the interface material can be 50 to 30% by weight. Specifically, the proportion of molybdenum in the interface material can be 55 to 65% by weight, 58 to 62% by weight, or 60% by weight, and the proportion of other elements in the interface material can be 45 to 35% by weight, 42 to 38% by weight, or 40% by weight. The interface material may also contain 0.01 to 0.2% by weight, preferably 0.01 to 0.1% by weight, of impurities such as S and P.

[0015] In one embodiment of the invention, the other elements and / or functional layers may comprise, and in particular may be composed of, the following materials: For other elements and / or functional layers, materials in powder form can be used, preferably iron-based materials (hereinafter also referred to as Fe-based materials), especially gas-atomized powders with the following chemical composition: C = 0.4 to 1.5% by weight Cr = 0.2 to 2.5% by weight Mn = 0.2 to 3% by weight Fe = Make up to 100% by weight Specifically, the powder may additionally comprise: S = 0.01 to 0.2% by weight P = 0.01 to 0.1% by weight.

[0016] Preferably, for other elements and / or functional layers, Fe-based materials in powder form can be used, particularly atomized powders with the following chemical composition: C = 0.1 to 0.8% by weight Cr = 11 to 18% by weight Mn = 0.1 to 1.5% by weight Mo = 0.1 to 5% by weight Fe = Make up to 100% by weight Specifically, the powder may additionally comprise: S = 0.01 to 0.2% by weight P = 0.01 to 0.1% by weight.

[0017] However, the other elements and / or functional layers may also be Fe-based materials with the following chemical composition: Fe0.2C1.4Cr1.4Mn, and in particular may also contain Mo = 0.1-5% by weight.

[0018] The particle size of the powder for the other elements and / or functional layers can be 5 to 25 μm, 10 to 45 μm, or 15 to 60 μm.

[0019] However, the other elements and / or functional layers may also comprise, in particular, the following materials: • Fe-based matrix + 30% Mo - particularly Fe0.2C1.4Cr1.4Mn + 30% Mo • MMC = a metal matrix composite material consisting of an Fe-based substrate and oxide ceramics (especially tribooxide ceramics), preferably composed of TiO2 or oxide ceramics composed of Al2O3TiO2 and / or Al2O3ZrO2 and / or Al2O3-20ZrO2 alloy systems, and / or the proportion of oxide ceramics in the material used (especially powder) is 5 to 50% by weight, preferably 35% by weight. In particular, MMC can be Fe14Cr2Mo and 5 to 50% by weight, preferably 35% by weight, of oxide ceramics.

[0020] • All-ceramic, such as TiO2 or Cr2O3 ·Cr3C2-25NiCr, especially Cr3C2-25NiCr and 20% Mo • AlSi and ceramics (such as TiO2, ZnO2), especially AlSi and 20% by weight Mo and ceramics.

[0021] If an adhesive layer is mentioned in this specification or claims (e.g., within a layer system), unless otherwise defined, it does not necessarily have to constitute an interface with one or more other layers of the layer system that are well-defined. For example, it may form a gradient transition to another layer, or it may lack a well-defined layer due to the interface profile.

[0022] If a chemical element is mentioned in this specification or claims, it does not necessarily have to exist in the form of an element, but may also exist in a compound.

[0023] According to a preferred first embodiment of the invention, the material of the adhesive layer is further selected such that it also forms chemical bonds with the material of the thermally sprayed functional layer to be applied and thus adheres thereto.

[0024] According to another equally preferred second embodiment, the adhesive layer is configured to have a surface roughness that allows the thermally sprayed functional layer to be applied to adhere to the adhesive layer to a sufficient degree, at least mechanically. For example, the roughness can be achieved through targeted columnar growth. The roughness of the adhesive layer can also be achieved by increasing the porosity.

[0025] Figure 2 An embodiment of the invention is shown, according to which the adhesion of the sprayed functional layer 3 to the substrate material 1 is ensured without activating the surface of the substrate material 1 through chemical bonding between the adhesive layer 5 and the substrate material 1 and through mechanical bonding and / or chemical bonding between the adhesive layer 5 and the functional layer 3.

[0026] In one embodiment, the coating of the cylinder perforation, particularly the layer system, can be formed in a gradually transitioning and / or gradient manner, especially in terms of chemical composition and / or structural construction. In this way, there is effectively only one layer with a gradually changing composition and / or morphology, i.e., a gradient layer, particularly a gradient layer system. A gradient layer, particularly a gradient layer system, can therefore be understood as containing a material chemically bonded to the surface of the cylinder's base material immediately adjacent to the first interface, i.e., the material of the adhesion layer, i.e., the interface material. As the distance from this surface increases, i.e., as the layer thickness increases, the layer material then gradually transitions to the layer material of the actual thermally sprayed protective layer to be applied, preferably a functional layer.

[0027] In one embodiment of the invention, a gradient layer having a gradually changing composition (i.e., having a gradual transition and / or gradient), particularly a gradient layer system, may include the following two variations: Variant 1 Interface materials gradually transition to functional layer materials, especially functional layer materials, which are suitable for: The layer with a gradually changing composition begins at the first interface with 0% by weight of functional layer material and 100% by weight of interface material, wherein the interface material may contain 60% by weight of molybdenum and 40% by weight of other elements; preferably, the interface material may consist of 60% by weight of molybdenum and 40% by weight of Ni5Al. The layer with the gradually changing composition ends with 100% by weight of functional layer and 0% by weight of interface material, such that the end of the gradient layer at least partially forms the perforated shell surface of the cylinder and can serve as the functional layer there.

[0028] Variant 2 The interface material may contain molybdenum and other elements, particularly those comprising, wherein said other elements preferably correspond to the material of the functional layer, and the interface material gradually transitions to the material of the functional layer, particularly the adhesive layer within the functional layer, wherein the following is suitable: The layer with a gradually changing composition begins at the first interface with 40% by weight of other elements and 50 to 70% by weight, preferably 60% by weight, molybdenum. The end of the layer with the gradually changing composition has 0 to 40% by weight of molybdenum and 60 to 100% by weight of other elements (these other elements particularly correspond to the material of the functional layer), preferably 20 to 40% by weight of molybdenum and 60 to 80% by weight of other elements, particularly preferably 30% by weight of molybdenum and 70% by weight of other elements, such that the end of the gradient layer at least partially forms the perforated inner shell surface of the cylinder and can serve as the functional layer there.

[0029] For example, variant 2 can have the following chemical composition and the following changes: Example 1: Other elements = Fe-substrate, especially functional layers = other elements = Fe-substrate Starting material: Fe-based material and 60% by weight of molybdenum, preferably Fe0.2C1.4Cr1.4Mn + 60% Mo End: Fe-based material, preferably Fe0.2C1.4Cr1.4Mn.

[0030] Example 2: Other elements = Fe-substrate, especially functional layers = other elements = Fe-substrate Starting material: Fe-based material and 60% by weight of molybdenum, preferably Fe0.2C1.4Cr1.4Mn + 60% molybdenum End: Fe-based material and 30% by weight of molybdenum, preferably Fe0.2C1.4Cr1.4Mn + 30% molybdenum.

[0031] In one embodiment of the invention, the proportion of interface material at the gradient layer with gradually changing composition can preferably decrease linearly or exponentially from the beginning to the end, especially in the case of variant 1 and / or variant 2, and / or the proportion of functional layer at the layer with gradually changing composition can preferably increase linearly or exponentially from the beginning to the end, especially in the case of variant 1 and / or variant 2.

[0032] According to a particularly preferred third embodiment of the invention, the coating of the cylinder perforation is configured in a gradient form. Immediately adjacent to the interface, the layer to be applied comprises a material chemically bonded to the surface of the cylinder's base material, i.e., particularly the material of the adhesive layer. As the distance from this surface increases, i.e., as the layer thickness increases, the layer material gradually transitions to the layer material of the actual thermally sprayed protective layer to be applied. This can be achieved, for example, through dual injection, wherein the injection of the adhesive layer decreases over time and / or the injection of the functional layer increases over time. In this way, there is effectively only one layer with a gradually changing composition and / or morphology, i.e., a gradient layer, particularly a gradient layer system.

[0033] In one embodiment of the invention, a layer with a gradually changing composition (i.e., a gradual transition), namely a gradient layer, can also be achieved by single injection, wherein two separate feeding devices, in particular two powder conveyors, can be used for the material of the adhesive layer and the functional layer, which are combined together in a Y-shaped component.

[0034] As an example of such an adhesive layer, a material composition comprising NiAl and Mo can be provided.

[0035] In one embodiment of the invention, the interface material may comprise molybdenum and Ni5Al, preferably composed of molybdenum and Ni5Al. Table 1 below shows the average adhesive tensile strength achieved under conventionally known activation (mechanical, corundum) and interface material composed of molybdenum and Ni5Al; in particular, the interface material may also consist of molybdenum and Ni5Al and impurities in proportions ranging from 0.1 to 0.3% by weight.

[0036] Table 1: Comparison of adhesive tensile strengths in conventionally known activated and interface materials composed of molybdenum and Ni5Al.

[0037] The present invention will now be described in detail with reference to embodiments and the accompanying drawings. Attached Figures

[0038] Figure 1 Showing existing technology to date Figure 2 The first specific embodiment of the present invention is shown. Figure 3 A second specific embodiment of the present invention is shown. Detailed Implementation

[0039] This embodiment relates to the invention according to a first embodiment. A perforation is coated on a cylinder, wherein the base material of the cylinder is an aluminum alloy, the perforation diameter is 85 mm, and the perforation depth is 170 mm. The perforation is coated with an iron-based thermal spray coating (95% Fe, 1.5% Cr, 1% Mn, 1% C) with a thickness of 200 to 300 micrometers. Atmospheric plasma spraying (APS) is used as the thermal spraying coating method. In this case, the powdered coating material is continuously melted in a plasma under the supply of energy and process gas, atomized in liquid form, and then internally applied to the base material of the cylinder wall, where it solidifies and forms a sealing layer. The plasma burner rotates during the melting process, thereby uniformly loading the layer onto the interior periphery of the cylinder wall.

[0040] If the layer is simply applied directly to the substrate material using the method described, it will not adhere sufficiently to the substrate material. According to existing technology, the surface of the substrate material can then be roughened or contoured.

[0041] In contrast, in this embodiment of the invention, an adhesion layer of 5 to 150 micrometers thick, consisting of a mixture of molybdenum and nickel-aluminum powders, is applied directly to the substrate material. The advantage of this material is that it forms chemical bonds with both the substrate material and the actual layer material. At the interface with the substrate material, compounds of, for example, ionic nature are generated; and at the interface between the adhesion layer and the layer material, ionic bonds are also formed, along with additional mechanical interlocking due to the rough spray coating. This ensures sufficient adhesion at both interfaces.

Claims

1. A cylinder for a piston-type internal combustion engine, wherein the cylinder includes at least one perforation having an inner shell formed of a base material, wherein in a region of the perforation, the base material is at least partially provided with a layer system, thereby forming a first interface between the base material and the layer system, and the layer system includes at least one thermally sprayed coating, which at least partially forms the shell surface of the perforation and can be used thereas as a functional layer, and wherein the first interface, apart from surface roughness resulting from the fabrication of the perforation, does not include a contour applied for surface activation, characterized in that, The material of the layer system contains molybdenum (hereinafter also referred to as the interface material) and at least one other element in the interface region with the substrate material, and is bonded to the substrate material by chemical bonding, and the interface material differs from the material of the functional layer in its composition and / or structure.

2. The cylinder according to claim 1, characterized in that, Structural measures for connecting the layer systems are provided within the layer system.

3. The cylinder according to claim 2, characterized in that, The structural measures include chemical bonding and / or interface roughness, which is preferably generated through the application of interface materials and / or through a gradual transition from interface materials to functional layer materials.

4. The cylinder according to any one of claims 1 to 3, characterized in that, The chemical bonding of interface materials to substrate materials is achieved through ionic bonds and / or covalent bonds.

5. The cylinder according to any one of claims 1 to 4, characterized in that, The interface material contains at least one chemical element that corresponds to a chemical element in the substrate material.

6. The cylinder according to any one of the preceding claims, characterized in that, The layer system forms at least one gradient in terms of chemical composition and / or structural configuration across the layer thickness from the first interface through the functional layer to the shell surface.

7. The cylinder according to any one of the preceding claims, characterized in that, At least one chemical element is present in the interface material, which corresponds to the chemical element in the functional layer.

8. A method for manufacturing a perforated cylinder for a piston internal combustion engine, wherein the method comprises the following steps: - Provides a cylinder with perforations, wherein the perforated inner shell is formed of a base material, and its surface does not include contours for activating the surface, except for the surface roughness resulting from the manufacture of the perforations. - A perforated inner shell loading layer system is provided, the layer system comprising an interface material at the interface with the substrate material, and wherein at least the layer system forming the cylinder bore surface is thermally sprayed and forms a functional layer. The characteristic feature is that the interface material comprises molybdenum and at least one other element, and is selected such that it forms a chemical bond with the substrate material, and the layer system is applied such that the interface material and the materials of the functional layers are chemically different in composition and / or structure.

9. The method according to claim 8, characterized in that, The region containing interface material between the substrate material and the functional layer is manufactured as a substrate layer forming a second interface with the functional layer, more precisely, configured such that the second interface has a structure suitable for mechanical activation, such as porosity and / or roughness and / or columnarity.

10. The method according to any one of claims 8 and 9, characterized in that, The layer system is applied entirely by thermal spraying.

11. The method according to any one of claims 8 and 10, characterized in that, The layer system is at least partially formed as a gradient layer in the direction of layer thickness.

12. The method according to claim 11, characterized in that, The transition from interface materials to functional layers is formed in the form of a gradient layer system.

13. An engine having a cylinder according to any one of claims 1 to 7.

14. A method for manufacturing an engine, characterized in that, The method includes the method steps according to any one of claims 8 to 12.

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