A method for preparing thermal barrier coating for complex surface

Abstract

The present application provides a method for preparing a thermal barrier coating on a complex surface, which belongs to the field of thermal spraying technology. The method first cleans the surface of the part and protects the non-spraying part; then performs sandblasting and roughening treatment on the spraying flow channel surface of the part to make it a uniform rough surface without metallic luster; then cools the part; then sprays the flow channel surface of the part according to the preset spraying points using the first preset spraying parameters, the first preset spraying parameters including the movement speed of the spray gun between each point and the spraying angle of each point; then sprays the Ni22Cr10Al1.0Y bottom layer on the sandblasting surface; finally sprays the ZrO2 8Y2O3 surface layer on the bottom layer surface. Through this method, the porosity of the zirconium oxide coating can be controlled below 3%, the unmelted particles are not more than 15%, the coating can withstand 1100°C thermal shock for not less than 20 times, and the mechanical properties reach more than 10MPa.

Description

Technical Field

[0001] The present application belongs to the field of thermal spraying technology, and in particular relates to a method for preparing a thermal barrier coating of a complex surface. Background Art

[0002] In order to improve the thrust-to-weight ratio, efficiency and effective load of aircraft engines, thermal barrier coating technology has been increasingly valued in the design and development of multiple engine components. The flame tube is a high-temperature component of the engine and is the place where combustion is organized. Its components need to withstand high-temperature heat input all year round. In order to effectively extend the life of its components, reduce cooling requirements and improve the thermal efficiency of the engine, it is necessary to provide the components with effective heat insulation, anti-oxidation and corrosion-resistant coatings.

[0003] In the related technologies, the preparation technology of aviation high temperature resistant products is generally based on aluminizing, aluminizing chromium and electron beam-physical vapor deposition MCrAlY. However, the coating is prepared under high temperature, and the parts are easily deformed after preparation, and a large amount of energy is consumed. Summary of the invention

[0004] In order to solve the problem that the preparation process of aviation high temperature resistant products in the related art prepares the coating under high temperature, the parts are very easy to deform after preparation, and a large amount of energy is consumed, the present invention provides a method for preparing a thermal barrier coating on a complex surface, and the technical solution is as follows:

[0005] A method for preparing a thermal barrier coating on a complex surface, the method comprising:

[0006] Step 1: Clean the surface of the parts and protect the non-spraying parts;

[0007] Step 2: Perform sandblasting and roughening treatment on the spraying flow channel surface of the parts to make it a uniform rough surface without metallic luster;

[0008] Step 3: Cool the parts;

[0009] Step 4: spraying the flow channel surface of the part according to the preset spraying points using the first preset spraying parameters, where the first preset spraying parameters include the movement speed of the spray gun between the points and the spraying angle of each point;

[0010] Step 5: spraying a Ni22Cr10Al1.0Y bottom layer on the sandblasting surface using a second preset spraying parameter;

[0011] Step 6: On the surface of the bottom layer, spray a ZrO2 8Y2O3 surface layer using the third preset spraying parameters.

[0012] Optionally, in step 1, a high temperature resistant tape is used to protect the non-sprayed parts of the parts, and protective tooling is used for protection.

[0013] Optionally, in step 2, the sandblasting surface roughness Ra≥4.

[0014] Optionally, in step 3, after the sandblasting is completed, the sandblasting tooling is replaced with a spraying fixture, and cold air is blown toward the part from below to cool the part.

[0015] Optionally, in step 4, the spraying point is determined according to the axial arc length of the flow channel surface of the part.

[0016] Optionally, in step 4, the flow channel surface is divided into four parts along the axial direction according to the axial arc length of the flow channel surface of the part, the axial arc length of each part is equal, and the spraying point is set at the boundary of each part.

[0017] Optionally, the spraying points are A, B, C, D, and E. During spraying, the robot holds the spray gun and moves forward, passing through points A, B, C, D, and E in sequence to achieve continuous spraying. The spray gun moves from point A to point E and then returns to point A for a spraying cycle; the spraying angles of points A and E are 60°, the spraying angles of points B and D are 75°, and the spraying angle of point C is 90°. The spraying angle refers to the angle between the spray gun and the surface where the point is located.

[0018] Optionally, the spray gun movement speed of the AB section and the DE section is 20 mm / s, and the spray gun movement speed of the BC section and the CD section is 30 mm / s.

[0019] Optionally, in step 5, the second preset spraying parameters include: powder feeding amount is 25%; argon pressure is 100±5Psi; argon flow rate is 80~100SCFH; auxiliary gas pressure is 50±5Psi; auxiliary gas flow rate is 5~15SCFH; powder feeding gas pressure is 50±5bar; powder feeding gas flow rate is 8~12; current is 500±5A; voltage is 75±5V; first stage spraying distance is 200±10mm; second stage spraying distance is 180±10mm; and the final coating thickness is 0.1mm~0.2mm.

[0020] Optionally, in step 6, the third preset spraying parameters include: powder feeding amount is 25%; argon pressure is 75±5Psi; argon flow rate is 80~100SCFH; auxiliary gas pressure is 50±5Psi; auxiliary gas flow rate is 5~15SCFH; powder feeding gas pressure is 2.4±0.2bar; powder feeding gas flow rate is 5~6; current is 550±5A; voltage is 65±5V; first stage spraying distance is 100±10mm; second stage spraying distance is 90±10mm; and the final coating thickness is 0.2mm~0.4mm.

[0021] The beneficial effects of the present invention are at least:

[0022] 1. Through plasma spraying technology, the temperature of the parts substrate is kept below 150°C;

[0023] 2. Through the reasonable and evenly distributed spraying point design and spraying parameters, a spraying angle change of 5 times during the spraying process was designed;

[0024] 3. Optimize the robot's running speed and angle between various points so that the coating porosity can reach less than 3%, the unmelted particles are no more than 15% (φmax≤60μm), and the coating can withstand 1100℃ thermal shock for no less than 20 times, and its mechanical properties reach more than 10MPa;

[0025] 4. Parts are not easily deformed, reducing energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A schematic flow chart of a method for preparing a thermal barrier coating on a complex surface provided in an embodiment of the present application;

[0027] Figure 2 A schematic diagram of the spray protection tooling structure provided in an embodiment of the present application;

[0028] Figure 3 A schematic diagram of the robot operation points provided in the embodiment of the present application;

[0029] Figure 4 Schematic diagram of the zirconium oxide sample and metallographic results provided in the examples of the present application. DETAILED DESCRIPTION

[0030] The present application is further described in detail below through specific implementation methods and drawings.

[0031] This embodiment provides a method for preparing a complex surface thermal barrier coating. Figure 1 , the method comprises the following steps:

[0032] Step 1: Clean the surface of the parts and protect the non-spraying areas.

[0033] When cleaning and protecting, you can use acetone and other organic solvents to clean the surface of the flow channel and adjacent surfaces of the parts to be sprayed until there is no visible oil on the surface, and then let the cleaned parts dry in the air. Then use anti-high temperature tape to protect the non-spraying parts of the parts, and use protective tooling for protection. The protection diagram is shown in the figure below. Figure 2 As shown, Figure 2 100 in the figure are protected parts.

[0034] For example, the part in this embodiment may be a flame tube head or a flame tube outer ring, and this embodiment does not specifically limit the part.

[0035] Step 2: The sprayed flow channel surface of the part is roughened by sandblasting to make it a uniform rough surface without metallic luster.

[0036] The spraying flow channel surface of the part is roughened by sand blasting. After the sand blasting treatment, the spraying flow channel surface of the part is a uniform rough surface without metallic luster.

[0037] In one embodiment, the roughness of the sandblasted surface subjected to the sandblasting roughening treatment is Ra≥4.

[0038] Step 3: Cool the parts.

[0039] After the sandblasting is completed, the sandblasting tooling is replaced with a spraying fixture, and cold air is blown from the bottom of the part to cool the part.

[0040] Step 4: spray the flow channel surface of the part according to the preset spraying points and using the first preset spraying parameters.

[0041] The first preset spraying parameters include the movement speed of the spray gun between various points and the spraying angle of each point.

[0042] In this embodiment, when setting the robot automatic spraying point, the flow channel surface can be divided into 4 parts along the axial direction according to the axial arc length of the part flow channel surface, and the axial arc length of each part is equal. The robot automatic spraying point is set at the boundary of each part. The distance between the spray gun and the flow channel surface is the spraying distance specified in the thermal spraying process parameters. The cross section between the spray gun and the flow channel surface is 45° to 90°, as close to 90° as possible. The spraying points are named A, B, C, D, and E. Figure 3 As shown, the flow channel surface is divided into 4 parts along the axial direction, namely, AB segment, BC segment, CD segment, and DE segment. During spraying, the robot clamps the spray gun and moves through points A, B, C, D, and E in sequence to achieve continuous spraying. The spray gun moves from point A to point E and then returns to point A for a spraying cycle. The spraying angles of points A and E are 60°, the spraying angles of points B and D are 75°, and the spraying angle of point C is 90°. The spraying angle refers to the angle between the spray gun and the surface where the point is located. Due to the different spraying angles between different points, the deposition efficiency of the coating in different areas is different. To ensure uniform coating thickness, this embodiment optimizes the movement speed of the spray gun between each point. The movement speed of the spray gun in the AB section and the DE section is 20 mm / s, and the movement speed of the spray gun in the BC section and the CD section is 30 mm / s. During the spraying process, compressed air is used to cool the part substrate. At the same time, after every 2 spraying cycles, the spraying is stopped, and the spraying is continued for 2 minutes to ensure that the substrate temperature does not exceed 150°C during the spraying process.

[0043] Step 5: On the sandblasted surface, spray the Ni22Cr10Al1.0Y base layer using the second preset spraying parameters.

[0044] When spraying the bottom layer, the bottom layer powder composition is Ni22Cr10Al1.0Y; the plasma spraying equipment is: Metco9M; the second preset spraying parameters include: powder feeding amount: 25%; argon pressure: 100±5Psi; argon flow: 80~100SCFH; auxiliary gas pressure: 50±5Psi; auxiliary gas flow: 5~15SCFH; powder feeding gas pressure: 50±5bar; powder feeding gas flow: 8~12; current: 500±5A; voltage: 75±5V; the first stage (i.e. the first spraying cycle) spraying distance (the spraying distance is the distance between the spray gun and the flow channel surface): 200±10mm, the second stage (i.e. the second spraying cycle) spraying distance: 180±10mm, and the final coating thickness is 0.1mm~0.2mm. During the spraying process, the parts are cooled by compressed air, and the parts are cooled from the side.

[0045] Step 6: On the surface of the bottom layer, spray a ZrO2 8Y2O3 surface layer using the third preset spraying parameters.

[0046] When spraying the surface layer, the zirconium oxide powder composition is ZrO2 8Y2O3; the plasma spraying equipment is: Metco9M; the third preset spraying parameters include: powder feeding amount: 25%; argon pressure: 75±5Psi; argon flow: 80~100SCFH; auxiliary gas pressure: 50±5Psi; auxiliary gas flow: 5~15SCFH; powder feeding gas pressure: 2.4±0.2bar; powder feeding gas flow: 5~6; current: 550±5A; voltage: 65±5V; first stage spraying distance: 100±10mm, second stage spraying distance: 90±10mm, and the final coating thickness is 0.2mm~0.4mm. During the spraying process, the parts are cooled by compressed air, and the parts are cooled from the side.

[0047] Taking the flame tube head as an example, the sample and metallographic results of the coating prepared by the present invention are as follows: Figure 4 shown.

[0048] Step 7: Disassemble the fixture and clean the parts.

[0049] The present invention provides a process method for plasma spraying a zirconium oxide thermal barrier coating on a flame tube head, which can control the porosity of the zirconium oxide coating to below 3%, and the unmelted particles to be no more than 15% (φmax≤60μm). At the same time, the coating can withstand thermal shock of 1100°C for no less than 20 times, and its mechanical properties reach above 10MPa.

[0050] By adopting the present invention, the heating process of the spray powder in flight can be controlled through the stress distribution of the coating, and the oxide content and porosity content in the coating can be effectively adjusted to make the oxide content of the coating; at the same time, uniform spraying can disperse the heat during the spraying process to prevent local overheating.

[0051] The above only expresses the implementation methods of the present application, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the invention patent. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present application, which all belong to the protection scope of the present application. In addition, the parts that are not detailed in the present invention are all conventional technologies.

Claims

1. A method for preparing a complex surface thermal barrier coating, characterized in that: The method comprises: Step 1: Clean the surface of the parts and protect the non-spraying parts. Use acetone organic solvent to clean the surface of the flow channel and adjacent surfaces of the parts to be sprayed until there is no visible oil on the surface. Then let the cleaned parts dry in the air, and then use anti-high temperature tape to protect the non-spraying parts of the parts, and use protective tooling for protection; the parts are the flame tube head or the outer ring of the flame tube; Step 2: Perform sandblasting and roughening treatment on the spraying flow channel surface of the parts to make it a uniform rough surface without metallic luster; Step 3: Cool the parts; Step 4, according to the preset spraying points, the first preset spraying parameters are used to spray the flow channel surface of the part, and the first preset spraying parameters include the movement speed of the spray gun between each point, and the spraying angle of each point; the spraying points are determined according to the axial arc length of the flow channel surface of the part, and the flow channel surface is divided into 4 parts along the axial direction according to the axial arc length of the flow channel surface of the part, and the axial arc length of each part is equal, and the spraying points are set at the boundary of each part; the distance between the spray gun and the flow channel surface is the specified value of the spraying distance in the thermal spraying process parameters, the spray gun and the cross section of the flow channel surface are 45° to 90°, the spraying points are A, B, C, D, E, and the robot clamps the spray gun during spraying The spray gun moves from point A to point E and then returns to point A for a spraying cycle. The spraying angles of points A and E are 60°, the spraying angles of points B and D are 75°, and the spraying angle of point C is 90°. The spraying angle refers to the angle between the spray gun and the surface where the points are located. The moving speed of the spray gun in the AB and DE sections is 20mm / s, and the moving speed of the spray gun in the BC and CD sections is 30mm / s. During the spraying process, compressed air is used to cool the part substrate. At the same time, after every 2 spraying cycles, the spraying is stopped, and the spraying is continued for 2 minutes to ensure that the substrate temperature does not exceed 150°C during the spraying process. Step 5, on the sandblasted surface, spray the Ni22Cr10Al1.0Y bottom layer using the second preset spraying parameters, the second preset spraying parameters include: powder feeding amount is 25%; argon pressure is 100±5Psi; argon flow rate is 80-100SCFH; auxiliary gas pressure is 50±5Psi; auxiliary gas flow rate is 5-15SCFH; powder feeding gas pressure is 50±5bar; powder feeding gas flow rate is 8-12; current is 500±5A; voltage is 75±5V; first stage spraying distance is 200±10mm; second stage spraying distance is 180±10mm; final coating thickness is 0.1mm-0.2mm; Step 6. On the surface of the bottom layer, use the third preset spraying parameters to spray the ZrO2 8Y2O3 surface layer, and the third preset spraying parameters include: powder feeding amount is 25%; argon pressure is 75±5Psi; argon flow rate is 80~100SCFH; auxiliary gas pressure is 50±5Psi; auxiliary gas flow rate is 5~15SCFH; powder feeding gas pressure is 2.4±0.2bar; powder feeding gas flow rate is 5~6; current is 550±5A; voltage is 65±5V; first stage spraying distance is 100±10mm; second stage spraying distance is 90±10mm; final coating thickness is 0.2mm~0.4mm.

2. The method according to claim 1, characterized in that In step 2, the roughness of the sandblasting surface is Ra≥4.

3. The method according to claim 1, characterized in that In step 3, after the sandblasting is completed, the sandblasting tooling is replaced with a spraying fixture, and cold air is blown from the bottom of the part to cool the part.

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