Component having outer surface covered with multi-layer coating

Abstract

The invention relates to a component (1) having an outer surface (1a) covered with a coating (2) comprising at least: a) a first layer (3), and a first layer deposited on the outer surface (1a) of the component (1) and comprising at least two sub-layers (3a, 3b): i) a first sub-layer (3a) made of a material comprising at least one element selected from the group consisting of chromium, nickel, cobalt, phosphorus, nitrogen, niobium, alloys thereof and mixtures thereof; ii) a second sub-layer (3b) deposited on the first sub-layer (3a) and made of a material comprising at least two elements selected from the group consisting of chromium, nickel, tungsten, cobalt, carbon, nitrogen, alloys thereof and mixtures thereof; iii) a third sub-layer (3c) deposited on the second sub-layer (3b) and made of a material comprising at least one element selected from the group consisting of chromium, nickel, titanium, silicon, cobalt, phosphorus, nitrogen, alloys thereof and mixtures thereof, and b) a second layer (4) deposited on the first layer (3), the second layer being an amorphous carbon layer.

Description

Technical Field

[0001] This invention relates to the technical field of components for motor reduction gears, particularly components for motor reduction gears in aircraft engines (such as bearings for reduction gears in aircraft engines). Background Technology

[0002] The function of reduction gears, especially mechanical reduction gears, is to change the speed and torque ratio between the input and output shafts of a mechanical system.

[0003] New-generation bypass turbine engines, especially those with very high dilution, include mechanical reduction gears used to drive the fan shaft. Typically, the purpose of reduction gears is to convert the "fast" rotation of the power turbine shaft into the slow rotation of the shaft driving the fan.

[0004] This type of reduction gear consists of a central pinion (called the sun gear), a gear ring, and smaller pinions (called planet gears), which mesh between the sun gear and the gear ring. These planet gears are held in place by a chassis called a planetary gear carrier. Because the axes of rotation of the sun gear, gear ring, and planetary gear carrier coincide with the longitudinal axis X of the turbine engine, they are all planetary gears. Each planet gear has a different axis of rotation, which are evenly distributed along the same running diameter around the axis of the planetary gear mechanism. These axes are parallel to the longitudinal axis X.

[0005] Currently, various reduction gear structures exist. In existing bypass turbine engines, the reduction gears are planetary gear mechanisms or rotary gear mechanisms. In other similar applications, there are structures called differential architectures or composite architectures.

[0006] In a planetary gear mechanism, the planetary gear carrier is fixed, and the gear ring forms the output shaft of the device, rotating in the opposite direction to the sun gear.

[0007] In a planetary gear mechanism, the gear ring is fixed, and the output shaft of the planetary gear assembly rotates in the same direction as the sun gear.

[0008] In a differential gear mechanism, no component rotates at a fixed speed. The rotation direction of the gear ring is opposite to that of the sun gear and the planetary gear carrier.

[0009] A reduction gear can consist of one or more meshing stages. This meshing can be achieved through different methods such as contact, friction, or magnetic fields. There are various types of contact meshing, such as spur gear meshing, helical gear meshing, or herringbone gear meshing.

[0010] Bearings for reduction gears, especially sliding bearings for aircraft engine reduction gears, have various advantages, particularly limited size, the ability to withstand high radial loads at high speeds, and significantly improved reliability and dynamic performance.

[0011] Currently, bearings, especially sliding bearings of reduction gears (particularly those in aircraft engines), can be coated with various types of coatings to limit wear, reduce the impact of friction between mechanical parts, and thus limit the risk of seizure.

[0012] For example, copper-lead or copper-bismuth type coatings are used to cover the surfaces of bearings, such as sliding bearings. Coatings containing zinc-tin-lead alloys may also be mentioned. These coatings have a much lower Young's modulus than steel, and will peel off when the substrate deforms, limiting their lifespan. Similarly, the coefficients of thermal expansion of these coatings differ significantly from those of steel, and may peel off when the system is heated.

[0013] Therefore, these coatings are not entirely satisfactory, especially since their jamming limit is relatively low, and adverse consequences are quickly observed. This reduces the durability of the components.

[0014] Therefore, there is indeed a need to supply components with enhanced wear resistance, such as bearings, especially sliding bearings. Summary of the Invention

[0015] For this purpose, the present invention relates to a component having an outer surface covered with a coating, the coating comprising at least: a) A first layer, which is deposited on the outer surface of the component and comprises at least two sublayers: i) A first sublayer, the first sublayer being made of a material comprising at least one element selected from the group consisting of chromium, nickel, cobalt, phosphorus, nitrogen, niobium, alloys thereof, and mixtures thereof; ii) A second sublayer, deposited on the first sublayer, is made of a material containing at least two elements selected from the following: chromium, nickel, tungsten, cobalt, carbon, nitrogen, alloys thereof, and mixtures thereof; iii) A third sublayer, deposited on the second sublayer, is made of a material containing at least one element selected from: chromium, nickel, titanium, silicon, cobalt, phosphorus, nitrogen, alloys thereof, and mixtures thereof; b) A second layer, which is deposited on top of the first layer, is an amorphous carbon layer.

[0016] With the component according to the invention, improved wear resistance is achieved, for example, in various operating cycles, by using a coating with a Young's modulus and coefficient of thermal expansion close to that of steel. Furthermore, the coefficient of friction is minimized with the component according to the invention. Therefore, the durability of the component is improved by the invention.

[0017] Furthermore, the sublayer of the present invention ensures adhesion between the coating and the component surface. Additionally, in the event of tearing, the sublayer can also act as a solid lubricant, thereby allowing for an extension of the service life of the coating on the component, and thus increasing the service life of the component according to the present invention.

[0018] Preferably, the material of the first sublayer comprises at least one element selected from the following: chromium, nickel, phosphorus, nitrogen, niobium, alloys thereof, and mixtures thereof.

[0019] Advantageously, the material of the second sublayer comprises at least two elements selected from the following: chromium, nickel, tungsten, carbon, nitrogen, alloys thereof, and mixtures thereof.

[0020] Preferably, the first sublayer and the second sublayer are different. In other words, the materials of the first sublayer and the materials of the second sublayer are preferably different in properties.

[0021] According to the present invention, the first layer further includes: iii) A third sublayer, deposited on the second sublayer, is made of a material containing at least one element selected from: chromium, nickel, titanium, silicon, cobalt, phosphorus, nitrogen, alloys thereof, and mixtures thereof.

[0022] Advantageously, the hardness of the second layer is greater than or equal to, preferably strictly greater than, the hardness of the third sublayer.

[0023] According to a preferred embodiment, the second layer is a hydrogenated or non-hydrogenated amorphous carbon layer, preferably a hydrogenated amorphous carbon layer.

[0024] Amorphous carbon, also known as diamond-like carbon (DLC), is a type of coating containing carbon atoms.

[0025] Therefore, preferably, the second layer is a hydrogenated amorphous carbon layer (ac:H).

[0026] The wear resistance is further improved by the amorphous carbon layer, and the coefficient of friction is minimized.

[0027] Preferably, the carbon-carbon bonds in the amorphous carbon layer are sp 2 / sp 3 The ratio is between 1 and 3.

[0028] Through this specific ratio, the wear resistance is further improved.

[0029] Advantageously, the thickness of the coating is in the range of 0.5µm to 50µm.

[0030] According to a preferred embodiment, the hardness of the second layer is greater than or equal to, and more preferably strictly greater than, the hardness of the first layer.

[0031] Advantageously, the hardness of the second layer is greater than or equal to, and more preferably strictly greater than, the hardness of the second sublayer.

[0032] Therefore, preferably, the coating has a hardness gradient, and more preferably, a modulus gradient.

[0033] The hardness of the coating is preferably in the range of 1000 to 4000 Hv (Vickers hardness). Vickers hardness is determined by conventional methods well known to those skilled in the art, through nanoindentation or microhardness testing.

[0034] The Young's modulus of the coating is preferably in the range of 170 to 250 GPa. The Young's modulus is determined by nanoindentation experiments.

[0035] According to the specific implementation plan, the first layer also includes: iv) A fourth sublayer, deposited on the third sublayer, made of a material containing at least one element selected from: chromium, nickel, titanium, silicon, cobalt, phosphorus, nitrogen, alloys thereof, and mixtures thereof.

[0036] Advantageously, the hardness of the second layer is greater than or equal to, and more preferably strictly greater than, the hardness of the fourth sub-layer.

[0037] According to another specific implementation, the first layer further includes: v) A fifth sublayer, which is deposited on the fourth sublayer, is made of a material containing at least one element selected from: chromium, nickel, titanium, silicon, cobalt, phosphorus, nitrogen, alloys thereof, and mixtures thereof.

[0038] Advantageously, the hardness of the second layer is greater than or equal to, and more preferably strictly greater than, the hardness of the fifth sublayer.

[0039] Advantageously, the component according to the invention is a component of a motor reduction gear, more preferably a component of an aircraft motor reduction gear, even more preferably a bearing of an aircraft motor reduction gear, and even better still a sliding bearing of an aircraft motor reduction gear.

[0040] Advantageously, the component is a bearing, such as a sliding bearing.

[0041] Another object of the present invention is to provide a method for manufacturing a component according to the present invention, the method comprising the following steps: (a) A component according to the invention is provided, said component having an outer surface; (b) Forming at least a first sublayer, a second sublayer and a third sublayer on the outer surface to obtain the first layer as described above; (c) Form a second layer as described above on the first layer to obtain the coating.

[0042] The object of the present invention also includes at least one component as defined in any of the preceding claims. Attached Figure Description

[0043] Other objectives, advantages, and features will become apparent from the following description, which is given by way of example only and with reference to the accompanying drawings, in which: [ Figure 1 The image shows a component with a multi-layered coating on its outer surface for ease of illustration; [ Figure 2 The image shows a component whose outer surface is covered with a multi-layer coating according to a first embodiment of the present invention; [ Figure 3 The image shows a component whose outer surface is covered with a multi-layer coating according to a second embodiment of the present invention; [ Figure 4 The image shows a component whose outer surface is covered with a multi-layer coating according to a third embodiment of the present invention.

[0044] Subsequently, a series of numerical limits are contained within this range, especially in expressions such as “between… and…” and “…from… to…”.

[0045] Furthermore, the term "at least one" as used in this specification is equivalent to the term "one or more". Detailed Implementation

[0046] For ease of explanation, Figure 1 A component 1 with an outer surface 1a is shown, which is covered with a coating 2.

[0047] The coating 2 includes a first layer 3 deposited on the outer surface 1a of the component 1, and a second layer 4 deposited on the first layer 3.

[0048] The first layer 3 includes a first sublayer 3a, which is made of a material containing at least one element selected from: chromium, nickel, cobalt, phosphorus, nitrogen, niobium, alloys thereof, and mixtures thereof. The first sublayer 3a is deposited on the outer surface 1a of the component 1.

[0049] Preferably, the material of the first sublayer 3a includes at least one element selected from the group consisting of chromium, nickel, phosphorus, nitrogen, niobium, alloys thereof, and mixtures thereof.

[0050] The material of the first sublayer 3a can be a metal, a doped metal or a chromium-containing ceramic, a nickel alloy (such as a chromium-nickel alloy or even a nickel-phosphorus alloy), or a mixture of nitrogen and chromium (such as chromium nitride).

[0051] The first layer 3 also includes a second sublayer 3b deposited on the first sublayer 3a, the second sublayer being made of a material containing at least two elements selected from the following: chromium, nickel, tungsten, cobalt, carbon, nitrogen, alloys thereof, and mixtures thereof.

[0052] The material of the second sublayer 3b can be a nickel alloy (such as a chromium-nickel alloy), a mixture of nitrogen and chromium, or a mixture of carbon and tungsten (such as tungsten carbide).

[0053] In addition, the material of the second sublayer 3b can be doped with elements such as carbon or metals, such as silicon, chromium or titanium.

[0054] The first sublayer 3a and the second sublayer 3b can be different. Preferably, they are different. In other words, the materials of the first sublayer 3a and the second sublayer 3b preferably have different properties.

[0055] For example, if the material of the first sublayer 3a is a chromium-nickel alloy, then in this embodiment, the material of the second sublayer 3b is a different material from the chromium-nickel alloy.

[0056] Advantageously, the second layer 4 is a hydrogenated or non-hydrogenated amorphous carbon layer, preferably a hydrogenated amorphous carbon layer (ac:H).

[0057] Preferably, the carbon-carbon bonds in the second layer 4 are sp 2 / sp 3 The proportion is in the range of 1 to 3.

[0058] Preferably, the thickness of coating 2 is in the range of 0.5µm to 50µm.

[0059] The component 1 containing coating 2 can be manufactured by a method including the following steps: (a) Provide a component 1 having an outer surface 1a; (b) A first sublayer 3a and a second sublayer 3b are formed on the outer surface 1a to obtain the first layer as described above.

[0060] For example, sublayers 3a and 3b can be deposited by physical vapor deposition (PVD) or plasma-enhanced chemical vapor deposition (PECVD or PACVD (plasma-assisted chemical vapor deposition)); the second layer 4 is deposited by PACVD or PECVD to obtain better surface conditions and higher deposition rates.

[0061] (c) Form a second layer as described above on the first layer to obtain a coating.

[0062] Figure 2 A component 1 according to a first embodiment of the present invention is shown, having an outer surface 1a covered with a coating 2.

[0063] Like component 1 described above, coating 2 includes a first layer 3 deposited on the outer surface 1a of component 1, and a second layer 4 deposited on the first layer 3.

[0064] The first layer 3 also includes at least a first sublayer 3a and a second sublayer 3b.

[0065] The above preferred implementation scheme is also applicable to this first implementation scheme.

[0066] The first layer 3 also includes a third sublayer 3c deposited on the second sublayer 3b, the third sublayer being made of a material containing at least one element selected from: chromium, nickel, cobalt, phosphorus, titanium, silicon, nitrogen, alloys thereof, and mixtures thereof.

[0067] In this first embodiment, the second layer 4 is deposited on the third sublayer 3c.

[0068] Sublayer 3c is deposited in the same manner as sublayers 3a and 3b, for example, by physical vapor deposition (PVD) or plasma-enhanced chemical vapor deposition (PECVD or PAVCD). The second layer 4 is deposited by PACVD or PECVD to obtain better surface conditions and higher deposition rates.

[0069] Figure 3 A component 1 according to a second embodiment of the present invention is shown, having an outer surface 1a covered with a coating 2.

[0070] Similar to component 1 described in the first embodiment, coating 2 includes a first layer 3 deposited on the outer surface 1a of component 1, and a second layer 4 deposited on the first layer 3.

[0071] The first layer 3 also includes at least a first sublayer 3a, a second sublayer 3b, and a third sublayer 3c.

[0072] The same preferred embodiments described above and in the first embodiment also apply to this second embodiment.

[0073] The first layer 3 also includes a fourth sublayer 3d deposited on the third sublayer 3c, the fourth sublayer being made of a material containing at least one element selected from: chromium, nickel, titanium, silicon, cobalt, phosphorus, nitrogen, alloys thereof, and mixtures thereof.

[0074] In the second embodiment, the second layer 4 is deposited on the fourth sublayer 3d.

[0075] Sublayer 3d is deposited in the same manner as sublayers 3a, 3b and 3c, for example, by physical vapor deposition (PVD) or plasma-enhanced chemical vapor deposition (PECVD or PAVCD); the second layer 4 is deposited by PACVD or PECVD to obtain better surface conditions and higher deposition rates.

[0076] Figure 4 A component 1 according to a third embodiment of the present invention is shown, having an outer surface 1a covered with a coating 2.

[0077] Similar to component 1 described in the second embodiment, coating 2 includes a first layer 3 deposited on the outer surface 1a of component 1, and a second layer 4 deposited on the first layer 3.

[0078] The first layer 3 also includes at least a first sublayer 3a, a second sublayer 3b, a third sublayer 3c, and a fourth sublayer 3d.

[0079] The same preferred embodiments described above and in the first and second embodiments also apply to this third embodiment.

[0080] The first layer 3 also includes a fifth sublayer 3e deposited on the fourth sublayer 3d, the fifth sublayer 3e being made of a material containing at least one element selected from: chromium, nickel, cobalt, phosphorus, nitrogen, titanium, silicon, alloys thereof, and mixtures thereof.

[0081] In this third embodiment, the second layer 4 is deposited on the fifth sublayer 3e.

[0082] Similar to sublayers 3a, 3b, 3c and 3d, sublayer 3e is deposited, for example, by physical vapor deposition (PVD) or plasma-enhanced chemical vapor deposition (PECVD or PAVCD); the second layer 4 is deposited by PACVD or PECVD to obtain better surface conditions and higher deposition rates.

[0083] Example Five steel components were used, referred to below as components 1 to 5.

[0084] The pin-disc test was conducted according to DIN50324-07, ASTM G99-05 or ISO 18535 standards, and the results are shown in Table 1.

[0085] All pins are made of low-alloy steel and have a ground surface, as detailed in Table 1. The discs are identical, made of low-alloy steel and have a ground surface.

[0086] Component 1 undergoes thermochemical surface hardening treatment.

[0087] Component 2 is used directly without undergoing thermochemical treatment.

[0088] The surfaces of components 3 to 5 are covered with coatings of various properties. All information can be found in Table 1 below.

[0089] Table 1

[0090] Therefore, components 1 to 4 are comparative components. Component 5 is a component according to the invention, which is coated with an amorphous carbon layer having a sublayer with a thickness of 0.5 µm to 50 µm by PVD and PACVD.

[0091] These components are then tested to assess their wear rate.

[0092] The results are shown in Table 2 below. Wear rate is expressed in µm / s.

[0093] Table 2

[0094] Obviously, the wear rate of component 5 according to the present invention is significantly lower than that of comparative components 1 to 4.

[0095] Therefore, the component according to the invention allows for improved wear resistance.

Claims

1. Component (1) having an outer surface (1a) covered with a coating (2) comprising at least: a) a first layer (3) deposited on the outer surface (1a) of the component (1) comprising at least two sub-layers (3a, 3b): i) a first sub-layer (3a) made of a material comprising at least one element selected from the group consisting of chromium, nickel, cobalt, phosphorus, nitrogen, niobium, alloys thereof and mixtures thereof; ii) a second sub-layer (3b) deposited on the first sub-layer (3a) made of a material comprising at least two elements selected from the group consisting of chromium, nickel, tungsten, cobalt, carbon, nitrogen, alloys thereof and mixtures thereof; iii) a third sub-layer (3c) deposited on the second sub-layer (3b) made of a material comprising at least one element selected from the group consisting of chromium, nickel, titanium, silicon, cobalt, phosphorus, nitrogen, alloys thereof and mixtures thereof; and b) a second layer (4) deposited on the first layer (3), the second layer being an amorphous carbon layer.

2. The component of claim 1, wherein The material of the first sub-layer (3a) comprises at least one element selected from the group consisting of chromium, nickel, phosphorus, nitrogen, niobium, alloys thereof and mixtures thereof.

3. The component of claim 1 or 2, wherein, The material of the second sub-layer (3b) comprises at least two elements selected from the group consisting of chromium, nickel, tungsten, carbon, nitrogen, alloys thereof and mixtures thereof.

4. The component of any preceding claim, wherein, The first sub-layer (3a) and the second sub-layer (3b) are different.

5. The component of any preceding claim, wherein, The second layer (4) is a hydrogenated or non-hydrogenated amorphous carbon layer, preferably a hydrogenated amorphous carbon layer.

6. The component of any preceding claim, wherein, carbon-carbon bonds in the second layer (4) 2 / sp 3 The proportion is in the range of 1 to 3.

7. The component of any preceding claim, wherein The thickness of the coating (2) is in the range of 0.5 pm to 50 pm.

8. The component of any preceding claim, wherein, The first layer (3) further comprises: iv) a fourth sub-layer (3d) deposited on the third sub-layer (3c) made of a material comprising at least one element selected from the group consisting of chromium, nickel, titanium, silicon, cobalt, phosphorus, nitrogen, alloys thereof and mixtures thereof.

9. The component of claim 8, wherein, The first layer (3) further comprises: v) a fifth sub-layer (3e) deposited on the fourth sub-layer (3d) made of a material comprising at least one element selected from the group consisting of chromium, nickel, titanium, silicon, cobalt, phosphorus, nitrogen, alloys thereof and mixtures thereof.

10. A component according to any preceding claim, characterised in that, The component (1) is a bearing.

11. Method for manufacturing a component (1) as defined in any one of the preceding claims, comprising the following steps: (a) providing a component (1) having an outer surface (1a); (b) forming at least a first sub-layer (3a), a second sub-layer (3b) and a third sub-layer (3c) on the outer surface (1a) to obtain the first layer (3); (c) forming the second layer (4) on the first layer (3) to obtain the coating (2).

12. An aircraft comprising at least one component (1) as defined in any one of claims 1 to 10.

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