CN112063962B - Method for preparing uniform coating on surface of complex profile by PS-PVD - Google Patents
Method for preparing uniform coating on surface of complex profile by PS-PVD Download PDFInfo
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- 239000011159 matrix material Substances 0.000 claims abstract description 9
- 238000005507 spraying Methods 0.000 claims description 77
- 238000007789 sealing Methods 0.000 claims description 46
- 238000010438 heat treatment Methods 0.000 claims description 33
- 239000007921 spray Substances 0.000 claims description 30
- 239000000843 powder Substances 0.000 claims description 28
- 239000012720 thermal barrier coating Substances 0.000 claims description 11
- 230000001681 protective effect Effects 0.000 claims description 10
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- 230000007547 defect Effects 0.000 description 1
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- 238000010891 electric arc Methods 0.000 description 1
- 238000009713 electroplating Methods 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
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- C23C4/00—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge
- C23C4/12—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge characterised by the method of spraying
- C23C4/134—Plasma spraying
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Abstract
The invention discloses a method for preparing uniform coatings on the surfaces of a plurality of workpieces with complex profiles at one time by utilizing plasma physical vapor deposition (PS-PVD). according to the technical scheme, the workpieces to be sprayed can be accurately and uniformly preheated, all parts of the complex profiles are uniformly heated, and the uniformity of the coatings on the surfaces of the workpieces with complex profiles is improved; the invention can allow higher preheating temperature under the protection of vacuum and inert gas and under the condition that a workpiece matrix does not deform and change the structure, so that the temperature difference between coating particles and the matrix is reduced, the cooling speed of the coating is reduced, the generation of thermal stress is reduced, the coating is not easy to crack, and gas phase particles can be fully diffused when being sprayed to the surface of the matrix to form a regularly arranged columnar structure coating; in addition, the method is favorable for enhancing the bonding force between the coating and the substrate.
Description
Technical Field
The invention belongs to the technical field of coating preparation, and particularly relates to a method for preparing a uniform coating on the surface of a complex profile by using plasma physical vapor deposition (PS-PVD).
Background
In recent years, aerospace technology is rapidly developing, and a high-performance gas turbine engine is required to have a higher thrust-weight ratio. Therefore, new and higher demands are also being made on the blades inside the engine. The inlet temperature of the aero-engine with the thrust-weight ratio of 10 in front of the turbine is 1850-1988K, the inlet temperature of the first-class aero-engine with the thrust-weight ratio of 12-15 in front of the turbine is 2000-2100K, and the inlet temperature of the first-class aero-engine with the thrust-weight ratio of 15-20 in front of the turbine is higher and can reach 2100-2200K. Even with the most advanced film cooling techniques, the turbine blade will be in service at a surface temperature that far exceeds the ultimate service temperature of the superalloy material used for the blade. In addition, the film cooling method is technically well developed, and if the cooling effect is further improved by increasing the flow rate of the cooling gas, part of the performance of the engine is sacrificed, and energy is wasted. In this case, thermal barrier coating techniques have been developed.
Thermal barrier coatings, also known as TBCs, are a surface protection technique that deposits ceramic materials with high temperature resistance, low thermal conductivity, corrosion resistance, etc. on the surface of a metal substrate in the form of a coating, thereby increasing the service temperature and high temperature oxidation resistance thereof, extending the service life of turbine engine blades, and improving the engine efficiency, and are also key techniques for the core hot end components of advanced gas turbine engines. The current preparation methods of the thermal barrier coating mainly comprise three methods: atmospheric Plasma Spraying (APS), electron beam physical vapor deposition (EB-PVD), plasma physical vapor deposition techniques (PS-PVD).
Plasma-Physical Vapor Deposition (PS-PVD) is an advanced coating preparation technology that has been developed in recent years. The PS-PVD uses a high-power (180 kW) plasma spray gun to spray under ultralow working pressure (0.5-2 mbar). The plasma jet morphology and characteristics have changed greatly. Plasma gas is heated and dissociated into high-energy and high-pressure plasma in the electrode gun by electric arcs, and the high-energy and high-pressure plasma is violently expanded to form supersonic plasma jet after entering a vacuum chamber through a nozzle. The plasma jet becomes thick and long, the length can exceed 2m, and the diameter can increase to 200-400 mm.
The plasma physical vapor deposition technology adopts high-energy plasma jet generated by a high-power plasma spray gun to melt and gasify sprayed particles, and the melted/gasified particles reach the surface of a substrate at high speed along with the plasma jet and are deposited, so that gas-liquid-solid multiphase composite deposition is realized, and the microstructure of a coating is also controlled. The plasma physical vapor deposition technology combines the technical advantages of Plasma Spraying (PS) and vapor deposition (PVD), has the advantages of high deposition speed of the PS technology and the like, and can realize vapor deposition. Most importantly, PS-PVD can achieve deposition of non-line-of-sight region coatings. The plasma jet can be directed around to the shadow areas of the geometrically complex workpiece and achieve uniform deposition of the coating.
The substrate temperature in the PS-PVD coating preparation technology has an important influence on the coating structure. The coating structure is influenced most by the temperature of the substrate during pure vapor deposition, and the coating presents different structure characteristics along with the change of the temperature of the substrate. At lower temperatures (less than 500 c), the deposition efficiency of the coating is low and the bond strength between the coating and the substrate is low. The shadow effect plays a main role at the temperature of 700-900 ℃, the crystal grows into a coarse conical crystal, and the top of the conical structure presents a circular arch shape; when the temperature is higher (more than 1200 ℃), the surface diffusion plays a main role to form columnar crystals with preferred orientation, certain gaps exist between the columns, and pores between the columns can penetrate to the surface of the coating along the surface of the substrate.
The existing coating preparation technologies such as EB-PVD, APS, LPPS, HVOF and the like mainly adopt high-energy beam jet flow to preheat a workpiece when preparing a coating so as to reach the matrix temperature required by spraying and generate a thermal product protective layer in the preheating process. But the preheating of a large workpiece by plasma flame flow of the PS-PVD equipment is difficult to achieve uniformly. The temperature at the clamping end of the workpiece is low, the spraying requirement cannot be met, the workpiece is easy to be locally overheated in the middle of the jet flow, the workpiece is locally melted, in addition, the simultaneous preheating and spraying of multiple workpieces are difficult to realize by using the plasma flame flow for preheating, and the production efficiency is low. The two main reasons for this are that the effective heating range of the flame flow is limited, the temperature of the PS-PVD plasma jet near the nozzle outlet is the highest and can reach 15550K, but the plasma jet temperature is continuously reduced along with the increase of the spraying distance, in addition, the temperature distribution in the radial direction of the plasma flame flow is not uniform, the center temperature of the plasma jet is very high, and the edge temperature of the jet is low. On the other hand, PS-PVD has the advantages of electroplating, but the plasma jet has limited heating capacity for non-line-of-sight areas due to shielding of different parts of a workpiece with a complex profile.
Therefore, according to the PS-PVD process of the prior art, when a plurality of complex-profile workpieces are coated at one time, the uniformity of the coating at different positions is poor due to uneven preheating. In order to improve the thickness uniformity, microstructure uniformity and service life consistency of the PS-PVD coating prepared on the complex surface, a method suitable for PS-PVD equipment for preparing uniform coatings on the surfaces of a plurality of complex surface workpieces at one time is urgently needed.
Disclosure of Invention
In order to solve the defects of the prior art, the invention provides a method for preparing uniform coatings on the surfaces of a plurality of workpieces with complex profiles at one time by using plasma physical vapor deposition (PS-PVD), and the specific technical scheme of the invention is as follows:
a method for preparing a uniform coating on the surface of a complex profile by using PS-PVD is characterized in that a multi-degree-of-freedom workpiece preheating system is arranged on PS-PVD equipment, the preheating system comprises a workpiece transfer working tank, a preheating working tank and an automatic workpiece rotating table, wherein,
the workpiece transferring working tank is a stainless steel tank body and is connected with the spraying working tank through a vacuum flange, and a workpiece transferring operation arm is arranged inside the workpiece transferring working tank and is used for transferring workpieces;
the preheating working tank is a stainless steel tank body, the heating body is a graphite heating body, and the preheating working tank is connected with the workpiece transfer working tank through a vacuum flange and is used for preheating a workpiece to be sprayed;
the two automatic workpiece rotating tables are respectively arranged inside the spraying working tank and the preheating working tank and used for clamping workpieces to be sprayed;
the spray gun and the spray gun operating arm are arranged inside the spraying working tank and are used for realizing a gun moving procedure required by a spraying process in the spraying process;
the spraying working tank, the workpiece transferring working tank and the preheating working tank are three main working spaces, and the vacuum degrees are respectively controlled by independent vacuum control systems; the preheating working tank is a pre-vacuumizing heating bin;
the PS-PVD equipment also comprises auxiliary equipment, wherein a power supply system, an air supply and powder feeding system and a cooling system are connected with the spraying working tank through vacuum flanges, and the power supply system provides high-power direct current for the plasma spray gun; the gas supply and powder feeding system provides gas for generating plasma and spraying powder for the spraying system and provides protective gas for the preheating system; the cooling system provides cooling water for the PS-PVD equipment; the vacuum and dust removal system is connected with the spraying working tank, the workpiece transfer working tank and the preheating working tank through vacuum flanges and is used for vacuumizing and removing dust; the control system is connected with the preheating working tank through a vacuum flange, the vacuum degree in all the tank bodies is respectively controlled through a vacuum gauge, the gas flow in all the tank bodies is respectively controlled through a gas flow meter, and the temperature in all the tank bodies is respectively controlled through an infrared thermometer;
the PS-PVD equipment also comprises four switchable vacuum sealing doors, wherein the first switchable vacuum sealing door is arranged at one end of the spraying working tank and is used for maintaining the plasma spray gun, the spray gun and the spray gun operating arm; the second switchable vacuum sealing door is arranged between the spraying working tank and the workpiece transferring working tank; the third switchable vacuum sealing door is arranged between the workpiece transfer working tank and the preheating working tank; the fourth switchable vacuum sealing door is arranged at the other end of the preheating working tank;
specifically, the method comprises the following steps:
s1: setting spraying parameters, a workpiece preheating program and a workpiece transferring program;
s2: preheating a first batch of workpieces;
s2-1: opening a fourth switchable vacuum sealing door, loading a first batch of workpieces into a first clamp, and then fixing the first batch of workpieces onto an automatic workpiece rotating table in a preheating working tank;
s2-2: closing the fourth switchable vacuum sealing door, vacuumizing to ensure that the pressure in the spraying working tank and the preheating working tank is lower than-10 mbar;
s2-3: opening a switch of a heating body of the preheating working tank, detecting the substrate temperature of the workpieces through an observation window on the preheating working tank by using an infrared temperature measuring probe, heating the first batch of workpieces to a set preheating temperature, and then preserving heat;
s2-4: opening a third switchable vacuum sealing door and a second switchable vacuum sealing door, transferring a first batch of workpieces heated to the preheating temperature to the spraying working tank together with the first clamp by using the workpiece transferring operation arm, and closing the second switchable vacuum sealing door and the third switchable vacuum sealing door;
s3: preheating a second batch of workpieces;
s3-1: opening a gas switch of the preheating working tank, and filling protective gas into the preheating working tank until the air pressure is balanced with the atmospheric pressure;
s3-2: opening a fourth switchable vacuum sealing door, loading a second batch of workpieces into a second fixture, and then fixing the second batch of workpieces onto an automatic workpiece rotating table in a preheating working tank;
s3-3: closing the fourth switchable vacuum sealing door, and vacuumizing to enable the pressure in the preheating working tank to be lower than 10 mbar;
s3-4: opening a switch of a heating body of the preheating working tank, detecting the matrix temperature of the workpieces through an observation window on the preheating working tank by using an infrared temperature measuring probe, heating the second batch of workpieces to a set preheating temperature, and then preserving heat;
s4: spraying a first batch of workpieces;
s4-1: checking the spraying parameters, opening a working gas valve of the plasma spray gun, striking an arc, and gradually adjusting the gas flow to the set gas flow after the arc is stabilized;
s4-2: opening a powder feeder of a gas supply and powder feeding system filled with thermal barrier coating powder, adjusting the powder feeding rate to be 2-20g/min, adjusting the spraying distance to be 450-1400 mm, adjusting the rotating speed of a workpiece to be 0-30 rpm, adjusting the moving mode of a plasma spray gun, and after the adjustment is finished, beginning to deposit a ceramic coating;
s4-3: stopping powder feeding after the deposition of the ceramic coating is finished; gradually reducing the gas flow and extinguishing arc;
s4-4: after the spraying is finished, opening a second switchable vacuum sealing door and a third switchable vacuum sealing door, transferring a first batch of sprayed workpieces to a preheating working tank by using a workpiece transfer operation arm, and transferring a second batch of preheated workpieces to a spraying working tank;
s5: repeating the step S4, and spraying the second batch of workpieces;
s6: taking out the first batch of workpieces after the spraying is finished, and preheating the third batch of workpieces;
s6-1: opening a gas switch of the preheating working tank, and filling protective gas into the preheating working tank until the air pressure is balanced with the atmospheric pressure;
s6-2: opening a fourth switchable vacuum sealing door, taking out the first batch of sprayed workpieces, loading the third batch of workpieces into a first clamp, and fixing the third batch of workpieces onto an automatic workpiece rotating table in a preheating working tank;
s7: and repeating the steps S3-3, S3-4 and S4 until all workpieces are sprayed.
Further, the heating body of the preheating working tank is a graphite heating body, and the heating temperature is not higher than 1300 ℃.
Further, the flow rate of the spraying gas in the step S4-1 is Ar 20-40SLPM and He 40-70 SLPM;
further, in the step S4-2, the powder feeding rate is 2-20g/min, the spraying distance is 450-1400 mm, and the rotating speed of the workpiece is 0-30 rpm.
Further, the movement form of the gun body in the step S4-2 is fixed, up and down sweeping, left and right sweeping, snake sweeping or leaf-shaped sweeping.
Further, the protective gas is Ar.
The invention has the beneficial effects that:
1. the invention can realize accurate and uniform preheating of the workpiece to be sprayed, uniform heating of each part of the complex profile and improvement of the uniformity of the coating on the surface of the workpiece with the complex profile.
2. The invention can allow higher preheating temperature under the protection of vacuum and inert gas and under the condition that a workpiece matrix is not deformed and changed in structure, so that the temperature difference between coating particles and the matrix is reduced, the cooling speed of the coating is reduced, the generation of thermal stress is reduced, the coating is not easy to crack, and gas phase particles can be fully diffused when being sprayed to the surface of the matrix to form a regularly arranged columnar structure coating; in addition, the method is favorable for enhancing the bonding force between the coating and the substrate.
3. The preheating system can be used in cooperation with the traditional low-pressure plasma spraying technology, so that the workpiece can be preheated and sprayed at the same time, the streamlined spraying and the simultaneous spraying of multiple workpieces can be realized, the production efficiency can be improved, and the production period can be shortened.
4. The preheating system can transfer the sprayed or preheated workpieces in a vacuum environment, avoids repeated inflation and warehouse opening, and reduces production cost.
Drawings
In order to illustrate embodiments of the present invention or technical solutions in the prior art more clearly, the drawings which are needed in the embodiments will be briefly described below, so that the features and advantages of the present invention can be understood more clearly by referring to the drawings, which are schematic and should not be construed as limiting the present invention in any way, and for a person skilled in the art, other drawings can be obtained on the basis of these drawings without any inventive effort. Wherein:
FIG. 1 is a schematic diagram of a PS-PVD system including a multi-degree of freedom workpiece preheating system of the present invention;
FIG. 2(a) is a partial view of a workpiece preheated by a flame stream in accordance with example 1 of the present invention;
fig. 2(b) is a partial view of a workpiece using a multi-degree-of-freedom workpiece preheating system in embodiment 1 of the present invention.
FIG. 3(a) is a cross-sectional view showing the thickness distribution of the coating layer of the workpiece in example 2 of the present invention;
FIG. 3(b) is a schematic diagram of the thickness measuring positions of various profiles in embodiment 2 of the present invention;
fig. 4(a) -4 (g) are micrographs of a coating on a cross-section of a workpiece corresponding to positions 1-7 in fig. 4(h) in example 3 of the present invention.
The reference numbers illustrate:
1-spray gun and spray gun operating arm; 2-spraying a working tank; 3-a work piece transferring working tank; 4-a workpiece transfer manipulator; 5-preheating the working tank; 6-automatic workpiece rotating table; f1 — power supply system; f2-air supply and powder feeding system; f3 — cooling system; f4-vacuum and dust removal system; f5-control system; k1-first switchable vacuum sealing door; k2 — a second switchable vacuum sealing door; k3-third switchable vacuum sealing door; k4-fourth switchable vacuum tight door.
Detailed Description
In order that the above objects, features and advantages of the present invention can be more clearly understood, a more particular description of the invention will be rendered by reference to the appended drawings. It should be noted that the embodiments of the present invention and features of the embodiments may be combined with each other without conflict.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, however, the present invention may be practiced in other ways than those specifically described herein, and therefore the scope of the present invention is not limited by the specific embodiments disclosed below.
As shown in figure 1, a multi-degree-of-freedom workpiece preheating system is arranged on a PS-PVD device, the preheating system comprises a workpiece transfer working tank 3, a preheating working tank 5 and an automatic workpiece rotating table 6, wherein,
the workpiece transferring working tank 3 is a stainless steel tank body and is connected with the spraying working tank 2 through a vacuum flange, and the workpiece transferring operation arm 4 is installed inside the workpiece transferring working tank 3 and is used for transferring workpieces;
the preheating working tank 5 is a stainless steel tank body, the heating body is a graphite heating body, and the preheating working tank is connected with the workpiece transfer working tank 3 through a vacuum flange and is used for preheating a workpiece to be sprayed;
the two automatic workpiece rotating tables 6 are respectively arranged inside the spraying working tank 2 and the preheating working tank 5 and are used for clamping workpieces to be sprayed;
the spray gun and the spray gun operating arm 1 are arranged inside the spraying working tank 2 and are used for realizing a gun moving procedure required by a spraying process in a spraying process;
the spraying working tank 2, the workpiece transferring working tank 3 and the preheating working tank 5 are three main working spaces, and the vacuum degrees are respectively controlled by independent vacuum control systems; the preheating working tank 5 is a pre-vacuumizing heating bin;
the PS-PVD equipment also comprises auxiliary equipment, wherein a power supply system F1, a gas supply and powder feeding system F2 and a cooling system F3 are connected with the spraying working tank 2 through a vacuum flange, and the power supply system F1 provides high-power direct current for the plasma spray gun; the gas supply and powder feeding system F2 provides gas for generating plasma and spraying powder for the spraying system and provides protective gas for the preheating system; the cooling system F3 provides cooling water for the PS-PVD equipment; the vacuum and dust removal system F4 is connected with the spraying working tank 2, the workpiece transfer working tank 3 and the preheating working tank 5 through vacuum flanges and is used for vacuumizing and removing dust; the control system F5 is connected with the preheating working tank 5 through a vacuum flange, the vacuum degree in all the tank bodies is respectively controlled through a vacuum gauge, the gas flow in all the tank bodies is respectively controlled through a gas flow meter, and the temperature in all the tank bodies is respectively controlled through an infrared thermometer;
the PS-PVD equipment also comprises four switchable vacuum sealing doors K1, K2, K3 and K4, wherein the first switchable vacuum sealing door K1 is installed at one end of the spraying working tank 2 and is used for maintaining the plasma spray gun and the spray gun and spray gun operating arm 1; the second switchable vacuum sealing door K2 is arranged between the spraying working tank 2 and the workpiece transferring working tank 3; the third switchable vacuum sealing door K3 is arranged between the workpiece transfer working tank 3 and the preheating working tank 5; a fourth openable and closable vacuum sealing door K4 is installed at the other end of the preheating operating tank 5.
For the convenience of understanding the above technical aspects of the present invention, the following detailed description will be given of the above technical aspects of the present invention by way of specific examples.
Example 1
A duplex blade of a ground gas turbine of a certain model is sprayed by a PS-PVD surface YSZ ceramic layer, and the blade is preheated before being sprayed by a flame flow heating system and a multi-degree-of-freedom workpiece preheating system. As shown in fig. 2(a) and 2(b), after preheating for 15min by using flame flow, the temperature difference between the upper and lower edge plates of the blade and the middle position of the blade body is large, the temperature difference reaches 50-100 ℃, and the exhaust edge of the blade body is locally overheated after preheating; after the multi-degree-of-freedom workpiece preheating system is used for spraying, the exhaust edge of the blade is intact, and the exhaust hole is not deformed.
Therefore, the invention can realize accurate and uniform preheating of the workpiece to be sprayed and uniform heating of all parts of the complex profile.
Example 2
A duplex blade of an aero-engine of a certain model is sprayed by a PS-PVD surface YSZ ceramic layer, and the blade is preheated before being sprayed by a flame flow heating system and a multi-degree-of-freedom workpiece preheating system respectively. As shown in fig. 3(a) and 3(b), 3 sections are taken at the blade body position, the M section is the blade middle section, the P section is the section 14mm away from the M section upwards, the N section is the section 14mm away from the N section downwards, 7 points are selected at each section position, the coating thickness of each point is measured by using an eddy current thickness gauge, the average value is taken for 3 times at each point, and the coating thickness at different profiles of each section is analyzed.
Table 1 shows the thickness of the thermal barrier coating at different profiles of the blade heated by flame flow, and the data in the table show that the mean value of the thicknesses of the P-section ceramic layers of the first blade of the duplex body is about 80 μ M, the mean value of the thicknesses of the M-section ceramic layers is about 114 μ M, the mean value of the thicknesses of the N-section ceramic layers is about 78 μ M, the mean value of the thicknesses of the P-section ceramic layers of the second blade of the duplex body is about 78 μ M, the mean value of the thicknesses of the M-section ceramic layers is about 117 μ M, and the mean. The blade preheated by flame flow heating has uneven thickness of the coating on the blade after spraying, thick coating in the middle of the blade, thin coating near the upper and lower edge plates and thickness difference of 30-40 μm.
And table 2 shows the thickness of the thermal barrier coating at different molded surfaces of the blade using the multi-degree-of-freedom workpiece preheating system, and the data in the table shows that the uneven thickness of the coating on the blade after the blade is sprayed and preheated by using the multi-degree-of-freedom workpiece preheating system is obviously improved, and the uniformity of the coating thickness is improved.
TABLE 1 thermal barrier coating thickness at different profiles of blade heated by flame flow
TABLE 2 thermal barrier coating thickness at different profiles of blade using multi-degree of freedom workpiece preheating system
Example 3
The single-connected blade of an aero-engine of a certain model is sprayed by a PS-PVD surface YSZ ceramic layer. The method comprises the following specific steps:
s1: setting spraying parameters, specifically a spray gun current 2000A, a spray gun working gas flow (Ar: 30 SLPM; He: 60SLPM), a powder feeding speed (5g/min), a powder feeding carrier gas (10SLPM), a spraying distance (1200mm) and a gun moving program; setting a workpiece preheating program (preheating temperature is 800 ℃, preheating time is 5min), and setting a workpiece transferring program;
s2: opening a fourth switchable vacuum sealing door K4, loading the blade into a clamp, and fixing the blade on an automatic workpiece rotating table 6 in a preheating working tank 5;
s3: closing a fourth switchable vacuum sealing door K4, vacuumizing to ensure that the pressure in the spraying working tank 2 is 2mbar, the pressure in the preheating working tank 5 is 1mbar, and the pressure in the workpiece transferring working tank 3 is 0.08 mbar;
s4: opening a switch of a heating body of the preheating working tank 5, detecting the temperature of a workpiece substrate by using an infrared temperature measuring probe through an observation window on the preheating working tank 5, heating the first batch of workpieces to the specified preheating temperature of 800 ℃, and then preserving heat for 5 min;
s5: the second switchable vacuum sealing door K2 and the third switchable vacuum sealing door K3 are opened, the first batch of workpieces heated to the preheating temperature are transferred to the spraying working tank 2 by the workpiece transfer operating arm 4, and the second switchable vacuum sealing door K2 and the third switchable vacuum sealing door K3 are closed;
s6: checking the spraying parameters, opening a working gas valve, striking an arc, and gradually adjusting the gas flow to the specified gas flow after the electric arc is stabilized, wherein Ar: 30SLPM, He: 60 SLPM;
opening a powder feeder of an air supply and powder feeding system F2 filled with thermal barrier coating powder, adjusting the powder feeding rate to be 5g/min, adjusting the spraying distance to be 1200mm, and adjusting the moving mode of a plasma spray gun, wherein the gun body is fixed at the center of a blade and is fixed, and after the adjustment is finished, the ceramic coating is deposited for 15 min;
s7: stopping powder feeding after the deposition of the ceramic coating is finished; gradually reducing the gas flow and extinguishing arc;
s8: after the painting is completed, the doors K2 and K3 are opened, and the blade after the painting is completed is transferred to the preheating work tank 5 by the work transfer operation arm 4.
S9: and opening a gas switch of the preheating working tank 5, filling protective gas Ar into the tank until the air pressure is balanced with the atmospheric pressure, opening a K4 door, and taking out the blade.
As can be seen from the microstructure of the coating at different profiles of the blade section shown in fig. 4(a) -4 (g), the ceramic layers at different profiles of the blade after spraying are all in a typical quasi-columnar crystal structure, the ceramic layers have similar thickness, the ceramic layers and the bonding layer are perfectly combined, and the coating with a uniform structure can be prepared on the surface of a workpiece with a complex profile. After spraying, the ceramic layers on different molded surfaces of the blade are well combined with the bonding layer, and the bonding strength is greater than 60 Mpa. The coating after spraying has good service life, and the thermal shock service life at 1100 ℃ is more than 2000 times (heating for 5min, cooling for 5 min).
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (5)
1. A method for preparing a uniform coating on the surface of a complex profile by using PS-PVD is characterized in that a multi-degree-of-freedom workpiece preheating system is arranged on PS-PVD equipment, the preheating system comprises a workpiece transfer working tank (3), a preheating working tank (5) and an automatic workpiece rotating table (6),
the workpiece transferring working tank (3) is a U-shaped stainless steel tank body and is connected with the spraying working tank (2) through a vacuum flange, and a workpiece transferring operation arm (4) is installed inside the workpiece transferring working tank (3) and is used for transferring workpieces;
the preheating working tank (5) is a stainless steel tank body, the heating body is a graphite heating body, and the preheating working tank is connected with the workpiece transferring working tank (3) through a vacuum flange and is used for preheating a workpiece to be sprayed;
the two automatic workpiece rotating tables (6) are respectively arranged in the spraying working tank (2) and the preheating working tank (5) and used for clamping workpieces to be sprayed;
the spray gun and the spray gun operating arm (1) are arranged inside the spraying working tank (2) and are used for realizing a gun moving procedure required by a spraying process in a spraying process;
the spraying working tank (2), the workpiece transferring working tank (3) and the preheating working tank (5) are three main working spaces, and the vacuum degrees are respectively controlled by independent vacuum control systems; the preheating working tank (5) is a pre-vacuumizing heating bin;
the PS-PVD equipment also comprises auxiliary equipment, wherein a power supply system (F1), a gas supply and powder feeding system (F2) and a cooling system (F3) are connected with the spraying working tank (2) through a vacuum flange, and the power supply system (F1) provides high-power direct current for a plasma spray gun; the gas supply and powder feeding system (F2) provides gas for generating plasma and spraying powder for the spraying system and provides protective gas for the preheating system; the cooling system (F3) provides cooling water for the PS-PVD equipment; the vacuum and dust removal system (F4) is connected with the spraying working tank (2), the workpiece transfer working tank (3) and the preheating working tank (5) through vacuum flanges and is used for vacuumizing and removing dust; the control system (F5) is connected with the preheating working tank (5) through a vacuum flange, the vacuum degree in all the tank bodies is respectively controlled through a vacuum gauge, the gas flow in all the tank bodies is respectively controlled through a gas flow meter, and the temperature in all the tank bodies is respectively controlled through an infrared thermometer;
the PS-PVD apparatus further comprises four switchable vacuum sealing doors (K1, K2, K3, K4), wherein the first switchable vacuum sealing door (K1) is mounted at one end of the spray work tank (2) for maintenance of the plasma spray gun and the spray gun and gun handling arm (1); the second switchable vacuum sealing door (K2) is installed between the spraying work tank (2) and the workpiece transfer work tank (3); the third switchable vacuum sealing door (K3) is installed between the workpiece transfer work tank (3) and the preheating work tank (5); the fourth switchable vacuum sealing door (K4) is arranged at the other end of the preheating working tank (5);
specifically, the method comprises the following steps:
s1: setting spraying parameters, a workpiece preheating program and a workpiece transferring program;
s2: preheating a first batch of workpieces;
s2-1: opening a fourth switchable vacuum sealing door (K4), loading a first batch of workpieces into the first clamp, and then fixing the first batch of workpieces onto an automatic workpiece rotating table (6) in a preheating working tank (5);
s2-2: closing a fourth switchable vacuum sealing door (K4), vacuumizing to ensure that the pressure in the spraying working tank (2) and the preheating working tank (5) is lower than 10 mbar;
s2-3: opening a switch of a heating body of the preheating working tank (5), detecting the substrate temperature of the workpieces through an observation window on the preheating working tank (5) by using an infrared temperature measuring probe, heating the first batch of workpieces to a set preheating temperature, and then preserving heat;
s2-4: opening a third switchable vacuum sealing door (K3) and a second switchable vacuum sealing door (K2), transferring the first batch of workpieces heated to the preheating temperature to the spraying working tank (2) together with the first fixture by using a workpiece transfer operating arm (4), and closing the second switchable vacuum sealing door (K2) and the third switchable vacuum sealing door (K3);
s3: preheating a second batch of workpieces;
s3-1: opening a gas switch of the preheating working tank (5), and filling protective gas into the preheating working tank (5) until the air pressure is balanced with the atmospheric pressure;
s3-2: opening a fourth switchable vacuum sealing door (K4), loading a second batch of workpieces into a second fixture, and then fixing the second batch of workpieces onto an automatic workpiece rotating table (6) in a preheating working tank (5);
s3-3: closing the fourth switchable vacuum sealing door (K4), vacuumizing to enable the pressure in the preheating working tank (5) to be lower than-10 mbar;
s3-4: opening a switch of a heating body of the preheating working tank (5), detecting the matrix temperature of the workpieces through an observation window on the preheating working tank (5) by using an infrared temperature measuring probe, heating the second batch of workpieces to a set preheating temperature, and then preserving heat;
s4: spraying a first batch of workpieces;
s4-1: checking the spraying parameters, opening a working gas valve of the plasma spray gun, striking an arc, and gradually adjusting the gas flow to the set gas flow after the arc is stabilized;
s4-2: opening a powder feeder of a gas supply and powder feeding system (F2) filled with thermal barrier coating powder, adjusting the powder feeding rate to be 2-20g/min, adjusting the spraying distance to be 450-1400 mm, adjusting the rotating speed of a workpiece to be 0-30 rpm, adjusting the moving mode of a plasma spray gun, and after the adjustment is finished, beginning to deposit a ceramic coating;
s4-3: stopping powder feeding after the deposition of the ceramic coating is finished; gradually reducing the gas flow and extinguishing arc;
s4-4: after the spraying is finished, a second switchable vacuum sealing door (K2) and a third switchable vacuum sealing door (K3) are opened, the first batch of workpieces after the spraying is finished are transferred to a preheating working tank (5) by using a workpiece transfer operating arm (4), and the second batch of workpieces after the preheating is transferred to a spraying working tank (2);
s5: repeating the step S4, and spraying the second batch of workpieces;
s6: taking out the first batch of workpieces after the spraying is finished, and preheating the third batch of workpieces;
s6-1: opening a gas switch of the preheating working tank (5), and filling protective gas into the preheating working tank (5) until the air pressure is balanced with the atmospheric pressure;
s6-2: opening a fourth switchable vacuum sealing door (K4), taking out the first batch of sprayed workpieces, loading the third batch of workpieces into a first clamp, and fixing the third batch of workpieces onto an automatic workpiece rotating table (6) in a preheating working tank (5);
s7: and repeating the steps S3-3, S3-4 and S4 until all workpieces are sprayed.
2. The method for preparing the uniform coating on the surface of the complex profile by using PS-PVD according to claim 1, characterized in that the heating body of the preheating working tank (5) is a graphite heating body, and the heating temperature is not higher than 1300 ℃.
3. The method for preparing the uniform coating on the surface of the complex profile by using the PS-PVD according to the claim 1 or the claim 2, wherein the flow rate of the spraying gas in the step S4-1 is Ar 20-40SLPM and He 40-70 SLPM.
4. The method for preparing uniform coating on the surface of a complex profile by using PS-PVD according to claim 1 or 2, wherein the movement form of the gun body in the step S4-2 is fixed, up and down sweeping, left and right sweeping, snake sweeping or simulated blade sweeping.
5. The method for preparing the uniform coating on the surface of the complex profile by using PS-PVD according to claim 1 or 2, wherein the protective gas is Ar.
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| CN114015980B (en) * | 2022-01-10 | 2022-04-01 | 北京航空航天大学 | Method for preparing thermal barrier coating on surface of engine turbine blade |
| CN114086128B (en) * | 2022-01-17 | 2022-04-15 | 北京航空航天大学 | Coating preparation method for realizing high-efficiency operation of PS-PVD equipment |
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| CN201172685Y (en) * | 2008-03-31 | 2008-12-31 | 北京世纪辉光科技发展有限公司 | Vertical producing apparatus for double-face plasma surface treated sheet metal |
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