CN110205626B - Functionally graded thermal barrier coating and preparation method thereof - Google Patents
Functionally graded thermal barrier coating and preparation method thereof Download PDFInfo
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- 239000012720 thermal barrier coating Substances 0.000 title claims abstract description 50
- 238000002360 preparation method Methods 0.000 title claims abstract description 10
- 238000004942 thermal barrier coating method Methods 0.000 title description 2
- 238000000576 coating method Methods 0.000 claims abstract description 59
- 239000011248 coating agent Substances 0.000 claims abstract description 55
- 239000000919 ceramic Substances 0.000 claims abstract description 35
- 238000000034 method Methods 0.000 claims abstract description 24
- 238000005516 engineering process Methods 0.000 claims abstract description 18
- 239000011159 matrix material Substances 0.000 claims abstract description 17
- 230000008569 process Effects 0.000 claims abstract description 7
- 229910045601 alloy Inorganic materials 0.000 claims abstract description 5
- 239000000956 alloy Substances 0.000 claims abstract description 5
- 239000000843 powder Substances 0.000 claims description 103
- 239000010410 layer Substances 0.000 claims description 87
- 229910001233 yttria-stabilized zirconia Inorganic materials 0.000 claims description 40
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 32
- 239000000758 substrate Substances 0.000 claims description 29
- 238000000151 deposition Methods 0.000 claims description 27
- 230000008021 deposition Effects 0.000 claims description 17
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 claims description 16
- 239000012790 adhesive layer Substances 0.000 claims description 16
- 229910052786 argon Inorganic materials 0.000 claims description 16
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 14
- 229910002080 8 mol% Y2O3 fully stabilized ZrO2 Inorganic materials 0.000 claims description 12
- 229910052593 corundum Inorganic materials 0.000 claims description 11
- 239000010431 corundum Substances 0.000 claims description 11
- 239000004576 sand Substances 0.000 claims description 11
- 238000005488 sandblasting Methods 0.000 claims description 10
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 8
- 229910000601 superalloy Inorganic materials 0.000 claims description 8
- 238000010146 3D printing Methods 0.000 claims description 7
- 238000001035 drying Methods 0.000 claims description 7
- 229910052759 nickel Inorganic materials 0.000 claims description 7
- JNDMLEXHDPKVFC-UHFFFAOYSA-N aluminum;oxygen(2-);yttrium(3+) Chemical compound [O-2].[O-2].[O-2].[Al+3].[Y+3] JNDMLEXHDPKVFC-UHFFFAOYSA-N 0.000 claims description 6
- 238000005524 ceramic coating Methods 0.000 claims description 6
- 229910001092 metal group alloy Inorganic materials 0.000 claims description 6
- 238000011112 process operation Methods 0.000 claims description 6
- 238000004506 ultrasonic cleaning Methods 0.000 claims description 6
- 229910019901 yttrium aluminum garnet Inorganic materials 0.000 claims description 6
- 239000003344 environmental pollutant Substances 0.000 claims description 5
- 231100000719 pollutant Toxicity 0.000 claims description 5
- 244000137852 Petrea volubilis Species 0.000 claims description 4
- 238000004140 cleaning Methods 0.000 claims description 4
- 238000011068 loading method Methods 0.000 claims description 4
- 230000003746 surface roughness Effects 0.000 claims description 4
- 230000007423 decrease Effects 0.000 claims description 3
- 238000000746 purification Methods 0.000 claims description 3
- 230000001105 regulatory effect Effects 0.000 claims description 3
- 238000007788 roughening Methods 0.000 claims description 3
- 239000000356 contaminant Substances 0.000 claims description 2
- 230000001276 controlling effect Effects 0.000 claims description 2
- 238000005498 polishing Methods 0.000 claims description 2
- 238000007751 thermal spraying Methods 0.000 abstract description 4
- 230000002035 prolonged effect Effects 0.000 abstract 1
- 239000000463 material Substances 0.000 description 14
- 238000012360 testing method Methods 0.000 description 6
- 239000007789 gas Substances 0.000 description 5
- 229910052751 metal Inorganic materials 0.000 description 5
- 239000002184 metal Substances 0.000 description 5
- 238000002844 melting Methods 0.000 description 4
- 238000005245 sintering Methods 0.000 description 4
- 230000006872 improvement Effects 0.000 description 3
- 230000008018 melting Effects 0.000 description 3
- 230000007704 transition Effects 0.000 description 3
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 230000004888 barrier function Effects 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 230000007797 corrosion Effects 0.000 description 2
- 238000005260 corrosion Methods 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 230000035699 permeability Effects 0.000 description 2
- 238000005507 spraying Methods 0.000 description 2
- 229910019655 synthetic inorganic crystalline material Inorganic materials 0.000 description 2
- 238000001291 vacuum drying Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
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- 238000009413 insulation Methods 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 238000003754 machining Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 238000007750 plasma spraying Methods 0.000 description 1
- 238000010248 power generation Methods 0.000 description 1
- 239000011343 solid material Substances 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
Classifications
-
- 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
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C24/00—Coating starting from inorganic powder
- C23C24/08—Coating starting from inorganic powder by application of heat or pressure and heat
- C23C24/10—Coating starting from inorganic powder by application of heat or pressure and heat with intermediate formation of a liquid phase in the layer
-
- 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
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C24/00—Coating starting from inorganic powder
- C23C24/08—Coating starting from inorganic powder by application of heat or pressure and heat
- C23C24/10—Coating starting from inorganic powder by application of heat or pressure and heat with intermediate formation of a liquid phase in the layer
- C23C24/103—Coating with metallic material, i.e. metals or metal alloys, optionally comprising hard particles, e.g. oxides, carbides or nitrides
-
- 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
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C24/00—Coating starting from inorganic powder
- C23C24/08—Coating starting from inorganic powder by application of heat or pressure and heat
- C23C24/10—Coating starting from inorganic powder by application of heat or pressure and heat with intermediate formation of a liquid phase in the layer
- C23C24/103—Coating with metallic material, i.e. metals or metal alloys, optionally comprising hard particles, e.g. oxides, carbides or nitrides
- C23C24/106—Coating with metal alloys or metal elements only
Abstract
The invention discloses a functionally graded thermal barrier coating and a preparation method thereof, namely, a bonding layer and a ceramic layer with continuously changing components and structures are prepared on a part matrix alloy by utilizing a laser near net forming technology. The thermal barrier coating prepared by the method is not constrained by the size and the geometric complexity of the die, the fixture and the tool and the parts in the traditional thermal spraying processing process; the prepared thermal barrier coating has the advantages of columnar grain orientation structure, high coating crystallinity, controllable thickness, more than 350MPa of bonding strength between the coating and the matrix and the like; the thermal cycle life of the functionally graded thermal barrier coating disclosed by the invention is far longer than that of the traditional pure YSZ and double-ceramic-layer thermal barrier coating, and the service life of a heat channel component and the inlet gas temperature of a gas turbine can be effectively prolonged by using the thermal barrier coating.
Description
Technical Field
The invention belongs to the technical field of thermal barrier coatings, and particularly relates to a functionally graded thermal barrier coating and a preparation method thereof.
Background
The thermal barrier coating technology is to cover materials with lower thermal conductivity and higher stability on the surface of a base material in a high-temperature environment to form a coating which not only has thermal barrier effect, but also can prevent oxidation, corrosion, erosion of foreign matters and the like from damaging the base material, and is widely applied to heat channel components of a ground heavy (power generation) gas turbine, such as transition sections of combustion chambers, flame tubes and the like and the surfaces of turbine blades at present.
The most mature thermal barrier coating ceramic layer material at present is 6 to 8 weight percent of Y 2 O 3 Partially stabilized ZrO 2 (6-8 YSZ for short), the YSZ material has higher fracture toughness and low thermal conductivity (2.12 W.m -1 ·K -1 1273K) and a coefficient of thermal expansion closer to the substrate (11.5×10) -6 K -1 293K-1273K) and the long-term safe use temperature is lower than 1200 ℃. However, for advanced heavy duty gas turbines with higher inlet gas temperatures (1600 ℃ and above), traditional YSZ coatings are obviously unsatisfactory due to the disadvantages of high oxygen permeability, easy sintering and phase transition at temperatures above 1200 ℃, easy corrosion at high temperatures, and the like. Therefore, developing a new material or structure with longer life at higher temperatures, lower thermal conductivity, and stronger resistance to sintering and ultra-high temperature phase change free capabilities has been the main development direction of advanced thermal barrier coating technology.
Hexaaluminate RMAl of magnetoplumbite structure 11 O 19 The (R=La-Gd; M=Mg, mn-Zn) material has the advantages of low heat conductivity, high thermal expansion coefficient, sintering resistance, no phase change below 2000 ℃, low high-temperature oxygen permeability and the like, and becomes a potential high-temperature thermal barrier coating new material for replacing the traditional YSZ material. However, the coefficient of thermal expansion and fracture toughness of hexaaluminate materials are lower than those of YSZ materials, resulting in a single hexaaluminate thermal barrier coating with very short thermal cycle life; in addition, partial amorphous phase is easy to form in the process of spraying hexaaluminate coating by atmospheric plasma, and under the condition of high temperature, the amorphous phase is converted into crystalline state to lead the volume of the coating to shrink, so that a large number of cracks are generated in the coating, and the service reliability of the hexaaluminate thermal barrier coating is severely restricted.
Disclosure of Invention
The invention aims to provide a functional gradient thermal barrier coating and a preparation method thereof, which aim at the defects of short thermal cycle life of a single hexaaluminate thermal barrier coating and the defects of the existing atmospheric plasma hexaaluminate coating spraying process, and the thermal barrier coating still has longer thermal cycle life at the temperature higher than 1200 ℃ and simultaneously has the performances of high-temperature phase stability, sintering resistance, high-efficiency thermal barrier and the like.
In order to achieve the above purpose, the present invention is realized by the following technical scheme:
a functionally graded thermal barrier coating comprises an adhesive layer and a ceramic layer which are sequentially arranged on a substrate.
The invention is further improved in that the substrate is a nickel-based superalloy.
A further improvement of the invention is that the bonding layer is gradually transited from a 100% NiCoCrAlY coating to a 100% 6-8 YSZ coating.
A further improvement of the invention is that the ceramic layer is a RMAl transition from a 100% 6-8 YSZ coating to 100% 11 O 19 A coating, wherein r=la to Gd; m=mg, mn to Zn.
A preparation method of a functionally graded thermal barrier coating comprises the following steps:
step (1), purifying and coarsening the surface of a nickel-based superalloy substrate;
step (2), adopting a laser near-net forming technology, and depositing a bonding layer with the thickness of 80-200 mu m on the surface of the high-temperature alloy matrix after the post-treatment in the step (1);
and (3) depositing a ceramic layer with the thickness of 200-400 mu m on the surface of the bonding layer in the step (2) by adopting a laser near-net forming technology.
A further improvement of the invention is that the cleaning treatment in step (1) is to remove oxides, oil stains and other contaminants from the substrate surface.
The invention is further improved in that the surface purification treatment adopts 320-800 mesh sand paper to polish and remove surface oxide, and then acetone and absolute ethanol solution are sequentially used for ultrasonic cleaning of oil stains and other pollutants on the surface of the matrix;
the surface roughening treatment adopts corundum sand to perform pressurized wet sand blasting to roughen the surface of the matrix, then acetone and absolute ethyl alcohol solution are sequentially used for ultrasonic cleaning of the corundum sand remained on the surface of the matrix, and the matrix is dried for later use;
wherein, corundum sand adopts 80-360 meshes, the sand blasting pressure is 0.2-0.6 MPa, and the surface roughness Ra of the substrate after sand blasting is more than or equal to 3 mu m.
The invention is further improved in that the adhesive layer coating process flow in the step (2) is as follows: firstly, drying the NiCoCrAlY metal alloy powder and the 6-8 YSZ ceramic powder used in the step (2), then fixing the nickel-based superalloy substrate treated in the step (1) on a processing workbench, respectively loading the dried NiCoCrAlY metal alloy powder and the 6-8 YSZ ceramic powder into two independent powder feeders with controllable rotating speeds, and starting to perform laser 3D printing on the bonding layer coating.
The invention further improves that the specific method for laser 3D printing of the bonding layer comprises the following steps: the focusing neodymium-doped yttrium aluminum garnet laser with the power of up to 2kW is used, the laser power is adjusted to be 200-250W, the radius of the laser beam is 0.83-2 mm, and the laser scanning speed is 10-50 mm.s -1 The powder feeding speed is 0-9 g.min -1 The method comprises the steps of carrying out a first treatment on the surface of the The whole process operation is carried out in an argon environment, and the argon flow is 5-200/min;
for the adhesive layer, controlling the thickness of each deposition layer to be 40-60 mu m; during the first layer deposition, the rotation speed of the NiCoCrAlY powder feeder is adjusted to 5-9 g.min -1 The rotation speed of the 6-8 YSZ powder feeder is 0 g.min 1 So that the first adhesive layer is a 100% NiCoCrAlY coating, and the rotation speed of the NiCoCrAlY powder feeder gradually decreases to 0 g.min when the third layer is deposited along with the increase of the layer number -1 The rotation speed of the 6-8 YSZ powder feeder is adjusted to 5-9 g.min -1 So that the second adhesive layer is a mixed coating of 80 percent of NiCoCrAlY and 20 percent of 6-8 YSZ, and the third adhesive layer is a 100 percent of 6-8 YSZ coating.
The invention is further improved in that the gradient ceramic coating process flow in the step (3) is as follows: first for RMAl 11 O 19 Drying the powder, and then using a focusing neodymium-doped yttrium aluminum garnet laser with the power of up to 2kW, adjusting the laser power to be 200-250W, the radius of the laser beam to be 0.5-2.5 mm, and the scanning speed of the laser to be 10-50 mm.s -1 The powder feeding speed is 0-12 g.min -1 The method comprises the steps of carrying out a first treatment on the surface of the The whole process operation is carried out in an argon environment, and the argon flow is 5-200/min;
for the gradient ceramic coating, the thickness of the 1 st to 5 th deposition layers is controlled to be 40 to 70 mu m, and the thickness of the last deposition layer is controlled to be 50 to 100 mu m; during the first layer deposition, the rotation speed of the 6-8 YSZ powder feeder is adjusted to be 4-9 g.min -1 ，RMAl 11 O 19 The rotational speed of the powder feeder was 0gmin 1 So that the first ceramic layer is a 100 percent 6-8 YSZ coating, and the rotation speed of the 6-8 YSZ powder feeder is reduced to 0 g.min when the number of layers is increased and the sixth layer is deposited -1 ，RMAl 11 O 19 The rotation speed of the powder feeder is regulated to 5-12 g.min -1 So that the second, third, fourth and fifth ceramic layers are 6-8 YSZ and RMAl 11 O 19 Hybrid coating wherein 6 to 8YSZ and RMAl 11 O 19 The mass percentage ratio of the components is 1:4, 2:3, 3:2 and 4:1 respectively, and the sixth layer is 100% RMAl 11 O 19 And (3) coating.
The invention has the following beneficial technical effects:
according to the preparation method of the functionally graded thermal barrier coating, the thermal barrier coating on the surface of the thermal channel part of the gas turbine is prepared, the thermal barrier coating is not limited by a die, a clamp and a special tool in the traditional thermal spraying processing process, the size and the geometric complexity of the part are not limited, and different parts correspond to the 3D models in the computer.
Further, the invention adopts the laser near-net forming technology to prepare the thermal barrier coating, which is different from other 3D printing technologies and traditional thermal spraying technologies, the laser near-net forming is a novel production technology comprising numerical control, computer, laser and other technologies, the laser focusing beam forms a small melting area on the substrate and the metal powder, the metal powder is injected to the melting part through gas flow, the laser beam moves, and the melting area is rapidly cooled and solidified to form a solid material firmly combined with the substrate.
The functionally graded thermal barrier coating provided by the invention has the following advantages:
1) The prepared thermal barrier coating has a functional gradient structure; 2) The prepared coating has high crystallinity, controllable thickness and good bonding strength between the coating and the matrix; 3) The coating produced has a columnar grain-oriented structure comprising segmented cracks in the thickness direction of the coating, suitable for thermal insulation applications.
Drawings
FIG. 1 is a schematic diagram of a laser near net shape machining process;
FIG. 2 is a functionally graded thermal barrier coating system including a NiCoCrAlY/YSZ bond coat and YSZ/RMAl 11 O 19 And a ceramic layer.
FIG. 3 is a thermal cycle life versus graph.
Reference numerals illustrate:
1-a substrate; 2-a processing platform; 3. 4-first and second powder feeders of controlled rotational speed; 5-laser beam; a 6-melting zone; 7-depositing a layer; 8-gradient thermal barrier coating; 9-a bonding layer; 10-ceramic layer.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings.
As shown in FIG. 2, the functionally graded thermal barrier coating 8 provided by the invention comprises a substrate 1, a bonding layer 9 and a ceramic layer 10 which are sequentially arranged on the substrate 1, wherein the substrate 1 is a nickel-based superalloy, the bonding layer 9 is a coating system with continuously changing components and structures, particularly a coating system with continuously changing components and structures, which gradually changes from a 100% NiCoCrAlY coating to a 100% 6-8 YSZ coating, and the ceramic layer 10 is a coating system with continuously changing components and structures, particularly a coating system with continuously changing components and structures, which changes from a 100% 6-8 YSZ coating to a 100% RMAl 11 O 19 (r=la to Gd; m=mg, mn to Zn) coating.
The invention provides a preparation method of a functionally graded thermal barrier coating, which comprises the following steps:
step (1), purifying and coarsening the surface of a nickel-based superalloy substrate;
the cleaning treatment is to remove oxides, oil stains and other pollutants on the surface of the substrate.
Further, the surface purification treatment can adopt 320-800 mesh sand paper to polish and remove surface oxides, and then acetone and absolute ethanol solution are sequentially used for ultrasonic cleaning of oil stains and other pollutants on the surface of the substrate.
Further, the surface roughening treatment can be carried out by adopting corundum sand to carry out pressurized wet sand blasting to roughen the surface of the matrix, then sequentially using acetone and absolute ethyl alcohol solution to ultrasonically clean the corundum sand remained on the surface of the matrix, and drying the matrix for later use.
Furthermore, the corundum sand can be 80-360 meshes, the sand blasting pressure is 0.2-0.6 MPa, and the surface roughness Ra of the substrate after sand blasting is more than or equal to 3 mu m.
Before step (2) is carried out, the NiCoCrAlY metal alloy powder, the 6-8 YSZ ceramic powder and the RMAl used in step (2) and step (3) are mixed 11 O 19 The powder is subjected to a drying process.
Before the step (2), a 3D model of the thermal barrier coating is established in a computer and layered, each layer plans a scanning path and is converted into a numerical control program for mechanical operation.
Step (2), adopting a laser near-net forming technology, and depositing a bonding layer with the thickness of 80-200 mu m on the surface of the high-temperature alloy matrix after the post-treatment in the step (1); the adhesive layer coating process flow is as follows: fixing the high-temperature alloy matrix treated in the step (1) on a processing workbench, respectively loading the dried NiCoCrAlY metal alloy powder and the 6-8 YSZ ceramic powder into two independent powder feeders with controllable rotating speeds, and starting to perform laser 3D printing on the bonding layer coating.
Further, the specific method for laser 3D printing of the bonding layer comprises the following steps: a focused neodymium-doped yttrium aluminum garnet (Nd: YAG) laser with the power of up to 2kW is used, the laser power is adjusted to be 200-250W, the radius of the laser beam is 0.83-2 mm, and the scanning speed of the laser is 10-50 mm.s -1 The powder feeding speed is 0-9 g.min -1 . The whole process operation is carried out in an argon environment, and the flow of the argon is 5-200/min.
Further, for the adhesive layer, the thickness of each deposited layer is controlled to be 40-60 μm. During the first layer deposition, the rotation speed of the NiCoCrAlY powder feeder is adjusted to 5-9 g.min -1 The rotation speed of the 6-8 YSZ powder feeder is 0 g.min -1 So that the first adhesive layer is a pure 100% NiCoCrAlY coating, and the rotation speed of the NiCoCrAlY powder feeder gradually decreases to 0 g.min when the third layer is deposited along with the increase of the layer number -1 The rotation speed of the 6-8 YSZ powder feeder is adjusted to 5-9 g.min -1 So that the second adhesive layer is a mixed coating of 80 percent of NiCoCrAlY and 20 percent of 6-8 YSZ, and the third adhesive layer is a pure 100 percent of 6-8 YSZ coating.
In the proceeding step (3)) Before, the NiCoCrAlY powder remaining in the NiCoCrAlY powder feeder was removed and after washing the dry feeder, the dried RMAl was removed 11 O 19 The powder is fed into the feeder.
And (3) depositing a ceramic layer with the thickness of 200-400 mu m on the surface of the bonding layer in the step (2) by adopting a laser near-net forming technology. The technological process of the gradient ceramic coating comprises the following steps: the laser power is adjusted to be 200-250W, the radius of the laser beam is 0.5-2.5 mm, and the scanning speed of the laser is 10-50 mm.s by using a focusing neodymium-doped yttrium aluminum garnet (Nd: YAG) laser with the power of up to 2kW -1 The powder feeding speed is 0-12 g.min -1 . The whole process operation is carried out in an argon environment, and the flow of the argon is 5-200/min.
Further, for the gradient ceramic coating, the thickness of the 1 st to 5 th deposition layers is controlled to be 40 to 70 mu m, and the thickness of the last deposition layer is controlled to be 50 to 100 mu m. During the first layer deposition, the rotation speed of the 6-8 YSZ powder feeder is adjusted to be 4-9 g.min -1 ，RMAl 11 O 19 The rotational speed of the powder feeder was 0 g.min 1 So that the first ceramic layer is a 100 percent 6-8 YSZ coating, and the rotation speed of the 6-8 YSZ powder feeder is reduced to 0 g.min when the number of layers is increased and the sixth layer is deposited -1 ，RMAl 11 O 19 The rotation speed of the powder feeder is regulated to 5-12 g.min -1 So that the second, third, fourth and fifth ceramic layers are 6-8 YSZ and RMAl 11 O 19 Hybrid coating wherein 6 to 8YSZ and RMAl 11 O 19 The mass percentage ratio of the components is 1:4, 2:3, 3:2 and 4:1 respectively, and the sixth layer is 100% RMAl 11 O 19 And (3) coating.
Example 1
And establishing a 3D model of the thermal barrier coating in a computer, layering the model according to the composition gradient of the prefabricated coating, planning a scanning path of each layer, and converting the scanning path into a numerical control program for mechanical operation.
Before the coating is prepared: the DZ411 nickel-base superalloy was wire-cut into a substrate 1 of 40mm by 10mm size, and the corners of the sample were rounded. Sequentially polishing the surface of a coating to be processed of the substrate 1 by adopting 320-mesh and 800-mesh sand paper, sequentially placing the substrate in acetone and absolute ethanol solution for ultrasonic cleaning for 30min, and removing oil stains and other pollutants on the surface; and (3) carrying out wet sand blasting treatment on the surface by adopting 120-mesh corundum sand under the pressure of 0.3MPa, sequentially placing the surface into acetone and absolute ethyl alcohol solution, and carrying out ultrasonic cleaning for 30min to remove residual corundum sand on the surface, wherein the surface roughness Ra=6μm of the substrate 1 after coarsening. The purified and coarsened substrate 1 is dried in a vacuum drying oven for later use.
The Ni23Co17Cr12Al0.5Y metal powder with the mark Amdry 365-1 and the 8YSZ ceramic powder with the mark Metco 204NS are adopted as bonding layer materials, and the 8YSZ ceramic powder and LaMgAl are adopted 11 O 19 And (3) taking the powder as a ceramic layer material, and placing the powder material into a vacuum drying oven for drying for 5 hours for later use.
Starting to prepare a tie layer coating: fixing a substrate 1 on a processing workbench 2, respectively loading Ni23Co17Cr12Al0.5Y metal powder and 8YSZ ceramic powder into a first powder feeder 3 and a second powder feeder 4 with controllable rotation speed, adjusting laser power to 250W, laser beam radius to 1.5mm and laser scanning speed to 50mm s during the first layer deposition -1 The powder feeding speed of the first powder feeder 3 was 9 g.min -1 The powder feeding speed of the second powder feeder 4 was 0 g.min -1 The method comprises the steps of carrying out a first treatment on the surface of the When the second layer is deposited, the laser power is adjusted to 250W, the radius of the laser beam is 1.5mm, and the scanning speed of the laser is 40 mm.s -1 The powder feeding speed of the first powder feeder 3 was 4 g.min -1 The powder feeding speed of the second powder feeder 4 was 1.5 g.min -1 The method comprises the steps of carrying out a first treatment on the surface of the When depositing the third layer, the laser power is adjusted to 250W, the radius of the laser beam is 1.5mm, and the scanning speed of the laser is 50 mm.s -1 The powder feeding speed of the first powder feeder 3 was 0 g.min -1 The powder feeding speed of the second powder feeder 4 was 9 g.min -1 And the whole argon environment is provided, and the argon flow is 200/min.
Starting to prepare a ceramic layer coating: cleaning the Ni23Co17Cr12Al0.5Y metal powder remained in the first powder feeder 3, and collecting LaMgAl 11 O 19 The powder is charged into the first powder feeder 3. During the deposition of the first layer, the laser power is adjusted to 220W, the radius of the laser beam is 1.65mm, and the scanning speed of the laser beam is 50mm·s -1 The powder feeding speed of the first powder feeder 3 was 0 g.min -1 The powder feeding speed of the second powder feeder 4 was 9 g.min -1 The method comprises the steps of carrying out a first treatment on the surface of the When the second layer is deposited, the laser power is adjusted to 250W, the radius of the laser beam is 1.5mm, and the scanning speed of the laser is 40 mm.s -1 The powder feeding speed of the first powder feeder 3 was 1.5 g.min -1 The powder feeding speed of the second powder feeder 4 was 4 g.min -1 The method comprises the steps of carrying out a first treatment on the surface of the When depositing the third layer, the laser power is adjusted to 250W, the radius of the laser beam is 1.5mm, and the scanning speed of the laser is 45 mm.s -1 The powder feeding speed of the first powder feeder 3 was 2.0 g.min -1 The powder feeding speed of the second powder feeder 4 was 3.25 g.min -1 The method comprises the steps of carrying out a first treatment on the surface of the When the fourth layer is deposited, the laser power is adjusted to 250W, the radius of the laser beam is 1.5mm, and the scanning speed of the laser is 45 mm.s -1 The powder feeding speed of the first powder feeder 3 was 3.25 g.min -1 The powder feeding speed of the second powder feeder 4 was 2.0 g.min -1 The method comprises the steps of carrying out a first treatment on the surface of the When depositing the fifth layer, the laser power is adjusted to 250W, the radius of the laser beam is 1.5mm, and the scanning speed of the laser is 40 mm.s -1 The powder feeding speed of the first powder feeder 3 was 4 g.min -1 The powder feeding speed of the second powder feeder 4 was 1.5 g.min -1 The method comprises the steps of carrying out a first treatment on the surface of the When depositing the sixth layer, the laser power is adjusted to 220W, the radius of the laser beam is 1.65mm, and the scanning speed of the laser is 50 mm.s -1 The powder feeding speed of the first powder feeder 3 was 12 g.min -1 The powder feeding speed of the second powder feeder 4 was 0 g.min -1 . And the whole argon environment is provided, and the argon flow is 200/min.
In the preparation process, along with the movement of the laser beam 5, the molten area 6 is rapidly cooled and solidified to form a deposition layer 7, the thickness of the bonding layer 9 of the prepared gradient thermal barrier coating 8 is 150 mu m, and the thickness of the ceramic layer 10 is 320 mu m.
Example 2
And further testing the bonding strength of the functionally graded thermal barrier coating prepared by the laser near-net forming technology. Samples required for tensile bond strength testing were prepared according to the requirements in ASTM 633-01 standard: the diameter of the sample is 23-25 mm, the length is 38.1mm, the coating thickness is more than 380 mu m, the number of the samples is 5, and the tensile load is 0.013-0.021 mm.s -1 Until a fracture occurs. When the tensile stress is 350MPa, fracture occurs in the coating, so that the bonding strength of the functionally graded thermal barrier coating prepared by the laser near net forming technology disclosed by the invention is more than 350MPa, which is far higher than that of the thermal barrier coating prepared by the traditional thermal spraying technology, and meets the metallurgical bonding standard.
Example 3
And further testing the thermal cycle life of the functionally graded thermal barrier coating prepared by the laser near net shape forming technology. By contrast, a thermal barrier coating of a conventional pure 8YSZ ceramic layer with a total thickness of 450 μm and LaMgAl with a total thickness of 450 μm were prepared by plasma spraying 11 O 19 The thermal barrier coating of the 8YSZ double ceramic layers adopts a controllable thermal barrier coating automatic thermal cycler to test the thermal cycle life of three thermal barrier coatings, and the specific test method is as follows: the surface of the coating and the surface of the substrate are heated by flame respectively, heated to 1050 ℃ and 950 ℃ in 120 seconds, kept for 180 seconds, cooled to room temperature in 120 seconds, circulated until the shedding area of the coating on the surface of the sample is 5%, regarded as the coating to be invalid, the test is stopped, the circulation number at the moment is recorded as the thermal cycle life of the coating, and each group of tests takes the average value of the thermal cycle life of 5 samples. Thermal barrier coating of traditional pure 8YSZ ceramic layer and LaMgAl 11 O 19 The thermal cycle life of the thermal barrier coating of the 8YSZ double ceramic layers and the thermal cycle life of the functional gradient thermal barrier coating of the invention are shown in figure 3, and the thermal cycle life of the functional gradient thermal barrier coating of the invention is far longer than that of the thermal barrier coating of the traditional pure 8YSZ ceramic layers and LaMgAl 11 O 19 Thermal cycle life of the thermal barrier coating of the 8YSZ dual ceramic layer.
Claims (3)
1. The preparation method of the functionally graded thermal barrier coating is characterized by comprising the following steps of:
step (1), purifying and coarsening the surface of a nickel-based superalloy substrate;
step (2), adopting a laser near-net forming technology, and depositing a bonding layer with the thickness of 80-200 mu m on the surface of the high-temperature alloy matrix after the post-treatment in the step (1); the adhesive layer coating process flow is as follows: firstly, drying NiCoCrAlY metal alloy powder and 6-8 YSZ ceramic powder used in the step (2), then fixing the nickel-based superalloy substrate treated in the step (1) on a processing workbench, respectively loading the dried NiCoCrAlY metal alloy powder and 6-8 YSZ ceramic powder into two independent powder feeders with controllable rotating speeds, and starting to perform laser 3D printing on the bonding layer coating;
the specific method for laser 3D printing of the junction layer comprises the following steps: the focusing neodymium-doped yttrium aluminum garnet laser with the power of up to 2kW is used, the laser power is adjusted to be 200-250W, the radius of the laser beam is 0.83-2 mm, and the laser scanning speed is 10-50 mm.s -1 The powder feeding speed is 0-9 g.min -1 The method comprises the steps of carrying out a first treatment on the surface of the The whole process operation is carried out in an argon environment, and the argon flow is 5-200/min;
for the adhesive layer, controlling the thickness of each deposition layer to be 40-60 mu m; during the first layer deposition, the rotation speed of the NiCoCrAlY powder feeder is adjusted to 5-9 g.min -1 The rotation speed of the 6-8 YSZ powder feeder is 0 g.min 1 So that the first adhesive layer is a 100% NiCoCrAlY coating, and the rotation speed of the NiCoCrAlY powder feeder gradually decreases to 0 g.min when the third layer is deposited along with the increase of the layer number -1 The rotation speed of the 6-8 YSZ powder feeder is adjusted to 5-9 g.min -1 The second adhesive layer is a mixed coating of 80 percent of NiCoCrAlY and 20 percent of 6-8 YSZ, and the third adhesive layer is a 100 percent of 6-8 YSZ coating;
step (3), adopting a laser near-net forming technology to deposit a ceramic layer with the thickness of 200-400 mu m on the surface of the bonding layer in the step (2);
the technological process of the gradient ceramic coating comprises the following steps: first for RMAl 11 O 19 Drying the powder, and then using a focusing neodymium-doped yttrium aluminum garnet laser with the power of up to 2kW, adjusting the laser power to be 200-250W, the radius of the laser beam to be 0.5-2.5 mm, and the scanning speed of the laser to be 10-50 mm.s -1 The powder feeding speed is 0-12 g.min -1 The method comprises the steps of carrying out a first treatment on the surface of the The whole process operation is carried out in an argon environment, and the argon flow is 5-200/min;
for the gradient ceramic coating, the thickness of the 1 st to 5 th deposition layers is controlled to be 40 to 70 mu m, and the thickness of the last deposition layer is controlled to be 50 to 100 mu m; during the first layer deposition, 6 to 8Y is adjustedThe rotation speed of the SZ powder feeder is 4-9 g.min -1 ，RMAl 11 O 19 The rotational speed of the powder feeder was 0 g.min 1 So that the first ceramic layer is a 100 percent 6-8 YSZ coating, and the rotation speed of the 6-8 YSZ powder feeder is reduced to 0 g.min when the number of layers is increased and the sixth layer is deposited -1 ，RMAl 11 O 19 The rotation speed of the powder feeder is regulated to 5-12 g.min -1 So that the second, third, fourth and fifth ceramic layers are 6-8 YSZ and RMAl 11 O 19 Hybrid coating wherein 6 to 8YSZ and RMAl 11 O 19 The mass percentage ratio of the components is 1:4, 2:3, 3:2 and 4:1 respectively, and the sixth layer is 100% RMAl 11 O 19 And (3) coating.
2. The method of claim 1, wherein the purifying treatment in step (1) is to remove oxides, oil stains and other contaminants on the substrate surface.
3. The method for preparing the functionally graded thermal barrier coating according to claim 2, wherein the surface purification treatment comprises the steps of removing surface oxides by polishing with 320-800 mesh sand paper, and then sequentially ultrasonically cleaning oil stains and other pollutants on the surface of the substrate with acetone and an absolute ethanol solution;
the surface roughening treatment adopts corundum sand to perform pressurized wet sand blasting to roughen the surface of the matrix, then acetone and absolute ethyl alcohol solution are sequentially used for ultrasonic cleaning of the corundum sand remained on the surface of the matrix, and the matrix is dried for later use;
wherein, corundum sand adopts 80-360 meshes, the sand blasting pressure is 0.2-0.6 MPa, and the surface roughness Ra of the substrate after sand blasting is more than or equal to 3 mu m.
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| 张国会.激光近净成形Inconel718/NiCrAlY/ZrO2功能梯度材料实验研究.中国优秀硕士学位论文全文数据库 工程科技Ⅰ辑.2019,第B020-419页. * |
| 张彦飞 ; 李芹 ; 曹学强 ; .一种长寿命热障涂层――LaMgAl_(11)O_(19)/YSZ双陶瓷层介绍.中国新技术新产品.2012,(13),第10-11页. * |
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