EB-PVD coating method for reducing roughness of coating on surface of part

Abstract

The invention discloses an EB-PVD coating method for reducing the roughness of a coating on the surface of a part, and belongs to the technical field of surface treatment. Abrasive particle flow is introduced into the surface treatment device, and the surface of the part is ground through the abrasive particle flow; taking out the part from the surface treatment device, putting the part into an ultrasonic device, and carrying out ultrasonic cleaning on the part in the ultrasonic device; the parts are taken out and put into drying equipment to be dried; the dried part is loaded into a coating protection clamp, and then the coating protection clamp is loaded into an EB-PVD coating chamber for coating; and after coating of the part is completed, the EB-PVD coating chamber is opened, and the part is taken out of the coating protection clamp. Firstly, a part is fully ground through the surface treatment device, the part with the flat surface is obtained, then ultrasonic cleaning is conducted, and finally coating is conducted, so that the binding force between a coating on the surface of the part and a base body is higher, and the coating density is better.

Description

Technical Field

[0001] The present invention relates to the technical field of surface treatment, and particularly to an EB-PVD coating method for reducing the surface coating roughness of parts. Background Art

[0002] Coatings are prepared on the surfaces of hot-end parts of aeroengines (such as combustion chambers and turbine blades), which can effectively improve the oxidation and corrosion resistance of the parts, reduce the surface temperature of the parts, and thus increase the service life of the parts (theoretically, if the surface temperature of the parts is reduced by 15 °C, the service life of the parts can be doubled). The EB-PVD (Electron Beam Physical Vapor Deposition) technology is to heat the target material (raw material to be coated) with an electron beam, so that the target material is evaporated into gaseous molecules or atoms by heating, and then deposited on the surface of the part to form a coating. Before preparing the coating, the surface of the part needs to be pretreated to improve the bonding force between the coating and the part substrate. The most commonly used pretreatment method at present is sandblasting. The main principle is to continuously impact the surface of the part with sand grains under high pressure / high speed to remove the scale and stains on the surface. The sandblasting process has the following disadvantages:

[0003] ① The surface roughness of the part after sandblasting treatment is poor, and the coating prepared on its surface is uneven (as Figure 1 shown), which affects the coating morphology, density and coating performance;

[0004] ② After sandblasting treatment, if the sand grains remaining on the surface of the part are not cleaned up (as Figure 3 shown), it is easy to cause interface pollution, reduce the bonding force between the coating and the substrate, and cause the coating to fall off. Summary of the Invention

[0005] The purpose of the present invention is to overcome the deficiencies of the prior art and provide an EB-PVD coating method for reducing the surface coating roughness of parts, that is, treating the surface of the part to be coated with abrasive flow to significantly reduce the surface roughness of the part.

[0006] The purpose of the present invention is achieved by the following technical solutions:

[0007] An EB-PVD coating method for reducing the surface coating roughness of parts, comprising the following steps:

[0008] S1: Loading the part into a surface treatment device;

[0009] S2: Introducing abrasive flow into the surface treatment device, and grinding the surface of the part with the abrasive flow;

[0010] S3: After the grinding of the part is completed, take out the part from the surface treatment device and put it into the ultrasonic device, and perform ultrasonic cleaning on the part in the ultrasonic device;

[0011] S4: After the cleaning is completed, take out the part and put it into the drying equipment for drying treatment;

[0012] S5: Load the dried part into the coating protection fixture, then load the coating protection fixture into the EB-PVD coating chamber, seal the EB-PVD coating chamber and evacuate the EB-PVD coating chamber;

[0013] S6: After the vacuum degree in the EB-PVD coating chamber reaches the preset value, turn on the heating gun and preheat the part in the EB-PVD coating chamber;

[0014] S7: After the temperature of the part reaches the preset value, turn on the evaporation gun and perform evaporation work on the target material. After the target material evaporates, coat the part;

[0015] S8: After the coating of the part is completed, open the EB-PVD coating chamber and take out the part from the coating protection fixture.

[0016] Further, the abrasive grains in the abrasive flow are hard material particles with a particle size less than 500 mesh, and the surface roughness of the part after grinding is not greater than Ra1.6.

[0017] Further, the material of the hard material particles is silicon carbide particles or alumina particles.

[0018] Further, a fresh water cleaning chamber and an alcohol cleaning chamber are provided in the ultrasonic device, and the part is cleaned at room temperature in both the fresh water cleaning chamber and the alcohol cleaning chamber.

[0019] Further, the part is first cleaned in the fresh water cleaning chamber for 10 - 15 minutes, and then cleaned in the alcohol cleaning chamber for 10 - 15 minutes.

[0020] Further, the preset value of the vacuum degree in the EB-PVD coating chamber is not greater than 0.01 Pa.

[0021] Further, the preheating temperature of the part is 850 - 950 °C, and the coating time of the part is 20 - 30 minutes.

[0022] Further, the surface treatment device includes a mounting base, a bottom plate, an intermediate plate, a cover plate, a spray head, guide posts, and a circulation pipe. The bottom plate is fixedly arranged on the mounting base. The intermediate plate is connected between the bottom plate and the cover plate. The lower ends of the guide posts are fixedly arranged on the mounting base. The bottom plate, the intermediate plate, and the cover plate are all provided with guide holes that cooperate with the guide posts. The bottom plate is provided with a lower mounting groove that cooperates with the part. A through collecting hole is arranged at the bottom of the lower mounting groove. The intermediate plate is provided with an upper mounting groove that cooperates with the part. The cover plate is provided with a spraying hole that cooperates with the upper mounting groove. One end of the circulation pipe is fixedly and sealingly connected to the collecting hole, and the other end of the circulation pipe is fixedly and sealingly connected to the spray head. The spray head cooperates with the spraying hole. A material return device and a material discharging device are sealingly connected to the circulation pipe. The material discharging device is arranged close to the spray head.

[0023] Further, the cover plate is provided with a spray head groove for mounting the spray head, and the spray head groove cooperates with the spraying hole.

[0024] Further, both the material return device and the material discharging device are electrically connected to the control center.

[0025] The beneficial effects of the present invention are as follows:

[0026] 1) In the present technology, first, the part is fully ground by the surface treatment device to obtain a part with a flat surface, then ultrasonically cleaned, and finally coated. This makes the bonding force between the surface coating of the part and the substrate higher, and the coating density better.

[0027] 2) In the present technology, by utilizing the mutual friction between finer hard abrasive grains and the surface of the part, the obtained surface of the part is flat, and even a mirror polishing effect can be achieved. When grinding the surface of the part, the abrasive fluid contacts the surface of the part under high-pressure extrusion and flows rapidly along the surface of the part, achieving the effects of cleaning the surface of the part and removing the oxide scale on the surface of the part. There is no residual abrasive grain on the surface of the part, so no part-coating interface pollution will be generated. At the same time, the nozzle position of the abrasive flow is fixed, and the part is fixed with a special fixture, which can ensure that the distance between all parts and the nozzle of the abrasive flow is the same, and can ensure that the surface treatment quality of parts in different batches is the same. Description of the Drawings

[0028] Figure 1 EB-PVD coating-substrate microstructure diagram of the uneven surface of the part after sandblasting for coating;

[0029] Figure 2 EB-PVD coating-substrate microstructure diagram of the part with residual sand grains after sandblasting and then coating;

[0030] Figure 3EB-PVD coating-substrate microstructure diagram of the part after abrasive flow machining and then coating

[0031] Figure 4 Schematic connection structure diagram of the surface treatment device

[0032] Figure 5 Schematic side view connection structure diagram between the bottom plate, the middle plate and the cover plate

[0033] Figure 6 Schematic setting structure diagram of the part on the bottom plate

[0034] Figure 7 Schematic setting structure diagram of the nozzle groove on the cover plate

[0035] In the figure, 1 - part, 2 - mounting seat, 3 - bottom plate, 4 - middle plate, 5 - cover plate, 6 - nozzle, 7 - guide post, 8 - circulation pipe, 9 - collection hole, 10 - lower mounting groove, 11 - upper mounting groove, 12 - injection hole, 13 - material return device, 14 - discharging device, 15 - nozzle groove. Detailed implementation manners

[0036] Next, the technical solutions of the present invention will be clearly and completely described in conjunction with the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative efforts fall within the scope of protection of the present invention.

[0037] Refer to Figures 3 - 7 , the present invention provides a technical solution:

[0038] An EB-PVD coating method for reducing the surface coating roughness of a part, comprising the following steps:

[0039] (1) Load the part 1 into the surface treatment device. The function of the surface treatment device is to grind the surface of the part 1. When grinding, the distance between the part 1 and the nozzle 6 is controlled within 10 - 20 cm, and the grinding pressure is 300 - 500 Mpa.

[0040] (2) Introduce abrasive flow into the surface treatment device, and grind the surface of the part 1 through the abrasive flow. The abrasive grains in the abrasive flow are hard material particles with a particle size less than 500 mesh. The surface roughness of the ground part 1 is not greater than Ra1.6. The material of the hard material particles is silicon carbide particles or alumina particles. The particle size of the abrasive grains is selected between 200 - 500 mesh. The grinding time is 3 - 5 min to ensure that the surface roughness of the part 1 ≤ Ra1.6. Generally, it is not less than 200 mesh. If the particle size is too small, the pretreatment time is longer and the effect of removing the oxide scale on the surface of the part 1 is not obvious.

[0041] (3) After the grinding of part 1 is completed, take out part 1 from the surface treatment device and put it into the ultrasonic device, and perform ultrasonic cleaning on part 1 in the ultrasonic device. A clean water cleaning chamber and an alcohol cleaning chamber are provided in the ultrasonic device, and part 1 is cleaned at room temperature in both the clean water cleaning chamber and the alcohol cleaning chamber. Part 1 is first cleaned in the clean water cleaning chamber for 10 - 15 minutes, and then cleaned in the alcohol cleaning chamber for 10 - 15 minutes. The ultrasonic device is a prior art. Part 1 is first ultrasonically washed with water and then ultrasonically cleaned with alcohol. After the grinding of part 1, ultrasonic cleaning is required to remove residual grinding particles or other stains on the surface.

[0042] (4) After the cleaning is completed, take out part 1 and put it into the drying equipment for drying treatment. The drying equipment is the equipment in the prior art, and the function of the drying equipment is to dry the cleaning liquid on part 1.

[0043] (5) Load the dried part 1 into the coating protection fixture, then load the coating protection fixture into the EB-PVD coating chamber, seal the EB-PVD coating chamber and evacuate the EB-PVD coating chamber. The coating protection fixture is a fixture in the prior art. The coating protection fixture has two functions. One is to clamp part 1, and the other is to protect part 1 and wrap the parts of part 1 that do not need coating.

[0044] (6) After the vacuum degree in the EB-PVD coating chamber reaches the preset value, turn on the heating gun and preheat part 1 in the EB-PVD coating chamber. The preset value of the vacuum degree in the EB-PVD coating chamber is not greater than 0.01 Pa.

[0045] (7) After the temperature of part 1 reaches the preset value, turn on the evaporation gun and perform evaporation work on the target. After the target is evaporated, coat part 1. The preheating temperature of part 1 is 850 - 950 °C, and the coating time of part 1 is 20 - 30 minutes.

[0046] (8) After the coating of part 1 is completed, open the EB-PVD coating chamber and take out part 1 from the coating protection fixture.

[0047] In some embodiments, the surface treatment device includes a mounting base 2, a bottom plate 3, an intermediate plate 4, a cover plate 5, a nozzle 6, a guide post 7, and a circulation pipe 8. The bottom plate 3 is fixedly arranged on the mounting base 2. The intermediate plate 4 is connected between the bottom plate 3 and the cover plate 5. The lower end of the guide post 7 is fixedly arranged on the mounting base 2. The bottom plate 3, the intermediate plate 4, and the cover plate 5 are all provided with guide holes that cooperate with the guide post 7. The bottom plate 3 is provided with a lower mounting groove 10 that cooperates with the part 1. A through collecting hole 9 is provided at the bottom of the lower mounting groove 10. The intermediate plate 4 is provided with an upper mounting groove 11 that cooperates with the part 1. The cover plate 5 is provided with a spraying hole 12 that cooperates with the upper mounting groove 11. One end of the circulation pipe 8 is hermetically and fixedly connected to the collecting hole 9, and the other end of the circulation pipe 8 is hermetically and fixedly connected to the nozzle 6. The nozzle 6 cooperates with the spraying hole 12. A material return device 13 and a material discharge device 14 are hermetically connected to the circulation pipe 8. The material discharge device 14 is arranged close to the nozzle 6. The cover plate 5 is provided with a nozzle groove 15 for mounting the nozzle 6, and the nozzle groove 15 cooperates with the spraying hole 12. Both the material return device 13 and the material discharge device 14 are electrically connected to the control center. Among them, the function of the guide post 7 is to better align the bottom plate 3, the intermediate plate 4, and the cover plate 5 together. The bottom plate 3, the intermediate plate 4, and the cover plate 5 are used in cooperation to protect the non-grinding area of the part 1. The bottom plate 3, the intermediate plate 4, and the cover plate 5 are made of stainless steel or high-strength steel. The thickness of the bottom plate 3 and the cover plate 5 is not less than 20 mm. In order to facilitate the installation / removal of the part 1, the depth of the lower mounting groove 10 in the bottom plate 3 is not greater than 15 mm, preferably 10 - 11 mm. The inner cavity dimensions of the bottom plate 3, the intermediate plate 4, and the cover plate 5 for abrasive flow are set according to the dimensions of the outer contour of the part 1. In order to ensure that there is no jamming phenomenon when installing or removing the part 1, there should be a certain gap between the inner cavity of the bottom plate 3, the intermediate plate 4, and the cover plate 5 of the surface treatment device and the part 1 in contact. The unilateral gap between the inner cavity of the bottom plate 3, the intermediate plate 4, and the cover plate 5 of the surface treatment device and the part in contact is 0.1 - 0.3 mm, preferably 0.15 mm. The width of the spraying hole 12 is 8 - 15 mm, preferably 10 mm. The width of the collecting hole 9 is 5 - 10 mm, preferably 7 mm. The bottom plate 3, the intermediate plate 4, and the cover plate 5 all have a clearance fit with the guide post 7, and the unilateral gap is 0.2 mm. The upper edge of the guide post 7 is rounded. The mounting base 2 is used to mount the bottom plate 3, the intermediate plate 4, and the cover plate 5 through the guide post 7. The circulation pipe 8 is used to transport the abrasive grains so that the abrasive grains can be recycled. The control center is a prior art and controls the coordinated operation of the material return device 13 and the material discharge device 14. The material return device 13 is a prior art and is used to process the impurities in the abrasive grains. The material discharge device 14 is a prior art and is used to pressurize and accelerate the abrasive grains.

[0048] Mounting base 2, bottom plate 3, intermediate plate 4, cover plate 5, nozzle 6, guide post 7, and circulation pipe 8

[0049] Advantages compared with the prior art:

[0050] 1) The surface roughness of the obtained part is low

[0051] In the prior art, sandblasting is used to pre-treat the surface of parts. The main principle is to continuously impact the surface of the parts with sand grains under high pressure to remove the oxide scale, stains, etc. on the surface. Due to the relatively large particle size of the selected sand grains, different sand grains have different particle sizes, different sand grain morphologies, or different sandblasting angles, resulting in an uneven surface (high roughness) of the parts. In the present invention, the main principle is to utilize the mutual friction between finer hard abrasive grains and the surface of the parts, and the obtained surface of the parts is flat (low roughness), and even a mirror polishing effect can be achieved.

[0052] 2) Less interface contamination between the part and the coating

[0053] In the existing sandblasting technology, the sand grains used have sharp edges. Even if round sand grains are selected, after multiple cyclic collisions, the sand grains will break into small sand grains with sharp edges. After high-speed impact on the parts, they are easily embedded in the surface of the parts and cannot be thoroughly cleaned. After EB-PVD coating, interface contamination is generated at the part-coating interface, reducing the bonding force of the coating and affecting the coating life. In the present invention, when grinding the surface of the parts, the abrasive fluid contacts the surface of the parts under high-pressure extrusion and flows rapidly along the surface of the parts, achieving the effect of "cleaning" the surface of the parts and removing the oxide scale on the surface of the parts. There is no residual abrasive grain on the surface of the parts, so that no part-coating interface contamination will be generated.

[0054] 3) The surface quality of the obtained parts is relatively consistent

[0055] In the prior art, sandblasting is used to pre-treat the surface of parts. The operator mainly holds the parts by hand and moves the parts back and forth at a distance of 10-20 cm from the nozzle of the fixed sandblasting machine, or fixes the parts on the tooling, and the operator holds the nozzle of the sandblasting machine by hand to ensure that the nozzle moves back and forth at a distance of 10-20 cm from the parts. In either case, it is impossible to ensure that the distance between all parts and the nozzle is the same, resulting in different surface treatment qualities of different parts. When the present invention performs surface treatment, the nozzle position of the abrasive flow is fixed, and the parts are fixed by a special fixture, which can ensure that the distance between all parts and the nozzle of the abrasive flow is the same, and can ensure that the surface treatment qualities of different batches of parts are the same.

[0056] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "bottom", "one end", "top", "middle", "the other end", "coaxial", "one side", "inner", "front", "center", "both ends", etc. is the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0057] In the present invention, unless otherwise clearly specified and defined, terms such as "arranged", "installed", "connected", "fixed", "hinged", etc. shall be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two components or the interaction relationship between two components. Unless otherwise clearly defined, for those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0058] The above are only the preferred embodiments of the present invention. It should be understood that the present invention is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be changed within the scope of the concept described herein through the above teachings or the technology or knowledge in related fields. And any changes and modifications made by those skilled in the art without departing from the spirit and scope of the present invention shall fall within the protection scope of the appended claims of the present invention.

Claims

1. An EB-PVD coating method for reducing the roughness of a part surface coating, characterized in that: The following steps are involved: S1: Loading the part (1) into the surface treatment device; S2: introducing an abrasive flow into the surface treatment device to grind the surface of the part (1) by the abrasive flow; S3: After the grinding of the part (1) is completed, the part (1) is taken out from the surface treatment device and placed in an ultrasonic device, and the part (1) is ultrasonically cleaned in the ultrasonic device; S4: After cleaning, the part (1) is taken out and placed in a drying device for drying; S5: placing the dried part (1) into a coating protection fixture, placing the coating protection fixture into an EB-PVD coating chamber, sealing the EB-PVD coating chamber and evacuating the EB-PVD coating chamber; S6: After the vacuum degree in the EB-PVD coating chamber reaches a preset value, start the heating gun and preheat the part (1) in the EB-PVD coating chamber; S7: After the temperature of the part (1) reaches a preset value, the evaporation gun is turned on to evaporate the target material, and after the target material evaporates, the part (1) is coated; S8: After the coating of the part (1) is completed, the EB-PVD coating chamber is opened, and the part (1) is taken out from the coating protection fixture.

2. The EB-PVD coating method for reducing the roughness of the coating on the surface of a part according to claim 1, characterized in that: The abrasive particles in the abrasive flow are hard material particles with a particle size less than 500 mesh, and the surface roughness of the part (1) after grinding is not greater than Ra1.

6.

3. The EB-PVD coating method for reducing the roughness of the coating on the surface of a part according to claim 2, characterized in that: The hard material particles are made of silicon carbide particles or aluminum oxide particles.

4. An EB-PVD coating method for reducing the roughness of a coating on a part surface according to any one of claims 1 to 3, characterized in that: The ultrasonic device is provided with a clean water cleaning chamber and an alcohol cleaning chamber, and the part (1) is cleaned at room temperature in both the clean water cleaning chamber and the alcohol cleaning chamber.

5. The EB-PVD coating method for reducing the roughness of the coating on the surface of a part according to claim 4, characterized in that: The parts (1) are first cleaned in the clean water cleaning chamber for 10 to 15 minutes, and then cleaned in the alcohol cleaning chamber for 10 to 15 minutes.

6. An EB-PVD coating method for reducing the roughness of a coating on a part surface according to any one of claims 1 to 3, characterized in that: The vacuum degree in the EB-PVD coating chamber reaches a preset value of no more than 0.01 Pa.

7. An EB-PVD coating method for reducing the roughness of a coating on a part surface according to any one of claims 1 to 3, characterized in that: The preheating temperature of the part (1) is 850-950° C., and the coating time of the part (1) is 20-30 minutes.

8. An EB-PVD coating method for reducing the roughness of a coating on a part surface according to any one of claims 1 to 3, characterized in that: The surface treatment device comprises a mounting seat (2), a base plate (3), an intermediate plate (4), a cover plate (5), a nozzle (6), a guide column (7) and a circulation pipe (8); the base plate (3) is fixedly arranged on the mounting seat (2); the intermediate plate (4) is connected between the base plate (3) and the cover plate (5); the lower end of the guide column (7) is fixedly arranged on the mounting seat (2); the base plate (3), the intermediate plate (4) and the cover plate (5) are all provided with guide holes matching with the guide column (7); the base plate (3) is provided with a lower mounting groove (10) matching with the part (1); the lower mounting groove ( A through collecting hole (9) is provided on the bottom of the intermediate plate (4), an upper mounting groove (11) cooperating with the part (1) is provided on the intermediate plate (4), an injection hole (12) cooperating with the upper mounting groove (11) is provided on the cover plate (5), one end of the circulation pipe (8) is sealed and fixedly connected to the collecting hole (9), the other end of the circulation pipe (8) is sealed and fixedly connected to the nozzle (6), the nozzle (6) is cooperating with the injection hole (12), a return device (13) and a discharge device (14) are sealedly connected to the circulation pipe (8), and the discharge device (14) is arranged close to the nozzle (6).

9. The EB-PVD coating method for reducing the roughness of the coating on the surface of a part according to claim 8, characterized in that: The cover plate (5) is provided with a nozzle groove (15) for mounting the nozzle (6), and the nozzle groove (15) cooperates with the spray hole (12).

10. The EB-PVD coating method for reducing the roughness of the coating on the surface of a part according to claim 8, characterized in that: The material return device (13) and the material discharge device (14) are both electrically connected to a control center.

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