CN109763090B - Anti-sintering long-life double-layer gradient columnar structure thermal barrier coating and preparation method thereof - Google Patents
Anti-sintering long-life double-layer gradient columnar structure thermal barrier coating and preparation method thereof Download PDFInfo
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Abstract
The invention discloses a sintering-resistant long-life double-layer gradient columnar structure thermal barrier coating and a preparation method thereof, wherein the sintering-resistant long-life double-layer gradient columnar structure thermal barrier coating comprises a toughening layer and a thermal insulation layer; the heat insulation layer is divided by a longitudinal gap and is formed by stacking N sublayers, the ratio of the thickness of each sublayer to the thermal conductivity of each sublayer is equal, and the thermal conductivity of the sublayers decreases from a first sublayer close to the bonding layer to the equal N sublayers in an equal difference mode; each sub-layer is formed by alternating layered deposition of a second thermal barrier coating material powder and a third thermal barrier coating material powder; the toughening layer accounts for 10-50% of the total thickness of the thermal barrier coating with the double-layer structure. The double-layer gradient columnar structure thermal barrier coating provided by the invention can realize the purpose of sintering resistance of the ceramic coating in a high-temperature environment, the fracture toughness of the coating is enhanced through the design of the toughening layer, the cracking driving force of the coating is reduced through the columnar structure design, and the long-life service of the thermal barrier coating is realized.
Description
Technical Field
The invention belongs to the technical field of coatings, and particularly relates to a sintering-resistant long-life double-layer gradient columnar structure thermal barrier coating and a preparation method thereof.
Background
The primary function of Thermal Barrier Coatings (TBCs) is to provide Thermal insulation protection for high temperature hot end metal components of aircraft engines and gas turbines so that the alloy substrate can be stably in service for extended periods of time at temperatures well beyond its temperature tolerance limits. Therefore, the most important evaluation indexes of the TBC are the heat insulation temperature and the service life of the TBC. Typically, the TBC as initially prepared, having a thickness of 300 to 500 μm, is thermally insulated from 50 to 300 ℃. However, under prolonged high temperature thermal exposure, the thermal insulation temperature of the TBC can be significantly reduced. Meanwhile, the coating is easy to crack and peel. Therefore, how to make the TBC maintain the thermal insulation function at high temperature and realize long-life service is one of the challenges to be solved in future TBC development.
The thermal insulation function of the TBC is attributed to its own low material thermal conductivity on the one hand; on the other hand, the TBC prepared by adopting the spraying method contains a large amount of micron and submicron pores, and also plays a good heat insulation role. However, the thermal insulation function of TBCs after high temperature service is significantly reduced, primarily due to the loss of healing of the insulation pores inside the coating as a result of sintering. On the other hand, the sintering also causes the coating to be obviously hardened, so that the strain tolerance of the coating is greatly reduced, and the coating is easy to crack and peel, thereby influencing the service life of the coating.
From the perspective of sintering resistance, achieving spontaneous regeneration of pores under high temperature service is a viable way to ensure that the thermal insulation performance of the coating does not significantly degrade. From the perspective of extended service life, the failure of a thermal barrier coating to crack is related to its own fracture toughness and the external environment induced crack driving force. Improving the fracture toughness of the TBC and simultaneously reducing the cracking driving force are the keys for realizing the long-life service of the TBC. The crack driving force of a TBC is positively correlated to its own thickness and elastic modulus. It is worth mentioning that the thermal insulation temperature of the coating is also positively correlated to the thickness of the coating. Therefore, how to reasonably reduce the coating thickness and the overall elastic modulus on the premise of ensuring the heat insulation functionality is an effective way to reduce the cracking driving force of the TBC.
In conclusion, the key to realize the TBC anti-sintering is to realize the spontaneous regeneration of the heat insulation pores in the heat exposure, the key to prolong the service life of the TBC is to improve the fracture toughness of the coating, and simultaneously, the coating with low thickness and high strain tolerance is optimally designed in the early stage of ensuring the heat insulation function so as to finally realize the synergistic design of anti-sintering and long service life.
Disclosure of Invention
The invention aims to provide a sintering-resistant long-life double-layer gradient columnar structure thermal barrier coating and a preparation method thereof, and aims to realize the synergistic design of sintering resistance and long service life. The composite laminated structure can ensure that the coating keeps high heat insulation function through spontaneous regeneration of pores in high-temperature service; the gradient structure can reasonably reduce the overall thickness of the coating on the basis of equal heat insulation design on the premise of ensuring the heat insulation functionality of the coating; the columnar structure can obviously reduce the integral elastic modulus of the coating and realize high strain tolerance, thereby reducing the cracking driving force of the coating; the introduction of the toughening layer can improve the fracture toughness of the thermal barrier coating; finally, the synergistic design of sintering resistance and long service life can be achieved, and the preparation of the high-performance thermal barrier coating is realized.
In order to achieve the purpose, the invention adopts the following technical scheme:
a sintering-resistant long-life double-layer gradient columnar structure thermal barrier coating comprises a toughening layer and a thermal insulation layer which are sequentially arranged on a metal bonding layer from bottom to top; the toughening layer comprises a plurality of layers of first sheet layer units; the heat insulation layer comprises N sub-layers which are sequentially arranged from bottom to top, N is a natural number within 2-20, and the heat insulation layer is divided into columns by longitudinal gaps; the ratio of the thickness of the different sub-layers to the thermal conductivity of the different sub-layers is equal, and the equal difference of the thermal conductivity from the first sub-layer to the Nth sub-layer is decreased; each sublayer comprises a first coating and a third lamellar unit which are alternately arranged, the first coating is arranged at the bottom layer of each sublayer, and the first coating which is not arranged at the bottom layer covers the first coating and the third lamellar unit below the first coating; the first coating comprises a plurality of layers of second lamellar units; the second lamellar unit and the third lamellar unit are respectively formed by second thermal barrier coating material powder and third thermal barrier coating material powder, and the density of lamellar layers of the first lamellar unit and the second lamellar unit is larger than 90%; the density of the third slice unit is less than 60%; the thickness of the toughening layer accounts for 10-50% of the total thickness of the toughening layer and the heat insulation layer.
Furthermore, the width of the longitudinal gap along the direction perpendicular to the heat flow is 0.1% -3% of the thickness of the heat insulation layer, and the depth along the heat flow direction is 10% -100% of the thickness of the heat insulation layer.
Furthermore, M layers of second slice units are arranged between adjacent third slice units along the heat flow direction, wherein M is a natural number between 10 and 100; the volume of all the third sheet units is 10-50% of the total volume of all the second sheet units and all the third sheet units.
Furthermore, in the toughening layer, the bonding rate between the layers of the first sheet layer unit is not lower than 50%; the interlayer bonding rate of the second sheet unit in all the sub-layers in the heat insulation layer is less than or equal to 50%.
Further, the descending tolerance of the thermal conductivity of the first sub-layer to the N sub-layer is 0.1W/m.K-0.5W/m.K.
Furthermore, in the toughening layer, a first interlayer micropore is formed between two adjacent first layer units, and in the same layer of first layer units, a first layer of internal microcracks are formed between the adjacent first layer units; in the heat insulation layer, a second interlayer micropore is formed between two adjacent second sheet layer units, and in the same second sheet layer unit, a second interlayer microcrack is formed between the adjacent second sheet layer units.
Furthermore, the third sheet unit is arranged on the first coating at intervals, and the third sheet unit covers 10-50% of the surface area of the first coating below the third sheet unit.
A preparation method of a sintering-resistant long-life double-layer gradient columnar structure thermal barrier coating comprises the following steps:
step 3.1, depositing a second thermal barrier coating material;
step 3.2, spraying a suspension of third thermal barrier coating material powder, wherein the concentration of the suspension is 2-5 mol/L, and then repeating the step 3.1-the step 3.2 until each sublayer reaches the designed thickness;
and 4, preparing a longitudinal gap in the heat insulation layer by adopting a strong water flow impact method, and forming a columnar structure in the heat insulation layer.
Further, step 4 comprises the following steps:
step 4.1, heating the toughening layer, the heat insulation layer and the substrate to 900-1400 ℃ within 20min, and keeping the temperature at 900-1400 ℃ for no more than 2 min;
and 4.2, adopting strong water flow to impact in 10s to reduce the temperature of the toughening layer and the heat insulation layer to be below 200 ℃.
Further, in the step 2, the matrix is preheated to 300-500 ℃ in the deposition process; in step 3, the temperature of the substrate is controlled not to exceed 200 ℃ during the deposition process.
Compared with the prior art, the invention has the following beneficial effects:
the invention discloses a sintering-resistant long-life double-layer gradient columnar structure thermal barrier coating and a preparation method thereof, based on a mature low-cost plasma spraying process, a lamellar structure formed by loose nano-particle piles is introduced into the interior of a traditional compact micrometer lamellar layer, novel pores are spontaneously formed on the interface of the compact micrometer lamellar layer and the loose nano-particle piles at high temperature due to reverse shrinkage, and the orientation of the pores is vertical to the direction of heat flow, so that the reduction of the thermal conductivity is relieved, the TBC keeps high thermal insulation performance in high-temperature service, and the sintering resistance is realized.
In order to prolong the service life of the coating, the invention is designed from the aspects of improving the fracture toughness and reducing the cracking driving force. Reducing the crack driving force is achieved by gradient thickening and columnar strengthening strain tolerance. The gradient structure design of the heat insulation layer with the descending heat conductivity is realized by changing the spraying parameters, and the cracking and peeling driving force of a film-based system in the service process is obviously reduced by reducing the thickness of the coating under the heat insulation condition of the traditional coating and the like. The gradient structure is composed of N sublayers, the ratio of the thickness to the thermal conductivity of different sublayers is equal, and the thermal conductivity of the sublayers is gradually reduced from the first sublayer to the N sublayer. Therefore, the thicknesses of the first to N-th sublayers also necessarily decrease gradually. The thermal conductivity of the first sub-layer is the same as that of the conventional coating, and the thickness is 1/N of the thickness of the conventional coating, so that the conventional coating can be regarded as being composed of N first sub-layers, and the gradient structure designed by the invention is composed of the first sub-layers to the Nth sub-layers, so that the overall thickness of the coating can be reduced by the gradient structure provided by the invention. On the other hand, the thermal insulation performance of the coating can be expressed by the area thermal resistance, namely the ratio of the thickness of the coating to the thermal conductivity. Since the area thermal resistances of all the sub-layers are the same, the gradient structure designed by the invention has the same area thermal resistance as that of the coating formed by stacking the N first sub-layers. Based on the gradient structure, the overall thickness of the coating can be reduced on the premise of not weakening the heat insulation function. By designing the columnar structure, the overall elastic modulus of the coating is obviously reduced, and the strain tolerance of the coating is strengthened, so that the cracking driving force of the coating is reduced.
The improvement of fracture toughness is achieved by the introduction of a toughening layer. The lower limit of the thickness of the toughening layer is 10% to ensure that the whole coating has certain anti-cracking capability, and the upper limit of the thickness of the toughening layer is 50% to ensure that the heat-insulating property of the whole coating is not weakened.
Through the collaborative design of the double-layer and gradient columnar structures, the rapid decline of the heat insulation performance of the coating caused by high-temperature heat exposure is overcome, the reverse restriction relation of the thickness of the coating with a single structure on the heat insulation capacity and the service life is broken through, the cracking driving force of the coating is reduced, and the fracture toughness of the coating is enhanced, so that the collaborative design of sintering resistance and long service life of the thermal barrier coating with a novel structure is ensured. And the novel structure is based on a low-cost mature thermal spraying process, and has the characteristics of strong feasibility and capability of quickly realizing engineering application.
Drawings
FIG. 1 is a schematic surface topography of a thermal barrier coating with a double-layer gradient columnar structure prepared by a hybrid spray coating technique in combination with strong water flow impact;
FIG. 2 is a cross-sectional view taken along line A-A' of FIG. 1;
FIG. 3 is a schematic cross-sectional view of a thermal barrier coating with a double-layered gradient columnar structure after thermal exposure;
in the drawings: 1. the composite material comprises a base body, 2, a metal bonding layer, 3, a toughening layer, 4, a heat insulation layer, 41-a first sub-layer, 42-a second sub-layer, 43-a third sub-layer, 5, a longitudinal gap, 51-a first longitudinal gap, 52-a second longitudinal gap, 53-a third longitudinal gap, 54-a fourth longitudinal gap, 55-a fifth longitudinal gap, 56-a sixth longitudinal gap, 6, a first sheet layer unit, 7, a second sheet layer unit, 8, a third sheet layer unit, 91, a first interlayer micropore, 92, a second interlayer micropore, 101, a first interlayer microcrack, 102, a second interlayer microcrack, 11 and a pore formed in high-temperature service.
Detailed Description
The following are specific examples given by the inventor, and it should be noted that these examples are preferable examples of the present invention and are used for understanding the present invention by those skilled in the art, but the present invention is not limited to these examples.
A thermal barrier coating with an anti-sintering long-life double-layer gradient columnar structure comprises a toughening layer 3 arranged on a metal bonding layer 2 and a thermal insulation layer 4 arranged on the toughening layer 3; the toughening layer 3 comprises a plurality of layers of first layer units; the heat insulation layer 4 is formed by sequentially stacking N sub-layers from bottom to top, N is a natural number within 2-20, the value range of N is that the ratio of the thickness of different sub-layers to the thermal conductivity of the different sub-layers is the same, the thermal conductivity equal difference from the first sub-layer 41 to the N sub-layer is decreased gradually, the tolerance is 0.1W/m.K-0.5W/m.K, wherein the first sub-layer 41 is connected with the toughening layer 3; the thermal conductivity of the first sub-layer 41 of the thermal insulating layer 4 is less than or equal to 60% of the intrinsic thermal conductivity of the second thermal barrier coating material used for the thermal insulating layer 4.
The toughening layer 3 is formed by depositing first thermal barrier coating material powder, the toughening layer 3 accounts for 10% -50% of the total thickness of the thermal barrier coating with the double-layer structure, wherein the thermal barrier coating with the double-layer structure consists of the toughening layer 3 and the thermal insulation layer 4, and the fracture toughness of the first thermal barrier coating material is more than or equal to 2.5 MPa.m1/2. The lower limit of the thickness of the toughening layer is 10% to ensure that the whole coating has certain anti-cracking capability, and the upper limit of the thickness of the toughening layer is 50% to avoid weakening the heat insulation performance of the whole coating.
The heat insulation layer 4 accounts for 50% -90% of the total thickness of the double-layer structure thermal barrier coating, and the thermal conductivity of the second thermal barrier coating material and the third thermal barrier coating material does not exceed 2.5W/m.K at 1000-1600 ℃.
The double-layer structure thermal barrier coating is divided by longitudinal gaps 5 to form a columnar structure, the width of each longitudinal gap 5 in the direction perpendicular to the heat flow direction is 0.1% -3% of the thickness of the thermal insulation layer 4, the depth of each longitudinal gap 5 in the direction perpendicular to the heat flow direction is 10% -100% of the thickness of the thermal insulation layer 4, and the interval distance between every two adjacent longitudinal gaps 5 in the same extending direction is 1-10 times of the thickness of the thermal insulation layer 4; for example, in fig. 1, the distance between the first longitudinal slit 51 and the second longitudinal slit 52, the distance between the first longitudinal slit 51 and the third longitudinal slit 53, the distance between the fourth longitudinal slit 54 and the fifth longitudinal slit 55, and the distance between the fifth longitudinal slit 55 and the sixth longitudinal slit 56 are all in the range of 1 to 10 times the thickness of the thermal insulation layer 4. The longitudinal gap 5 divides the toughening layer 3 and the heat insulating layer 4 into a plurality of columnar structures. The cross section of each columnar structure is in an irregular pattern.
Each sublayer is provided with a first coating and a third lamellar unit 8 alternately, the bottom layer of each sublayer is a first coating, and the first coating which is not the bottom layer covers the first coating and the third lamellar unit 8 below the sublayer; the first coating comprises a plurality of layers of second lamellar units; the third lamellar units 8 are arranged on the first coating at intervals, cover 10-50% of the surface area of the first coating below the third lamellar units, the lower limit is to ensure that certain pores are formed for heat insulation, and the upper limit is to avoid forming overlarge pores to influence the service life. Each sub-layer is composed of a composite stack of a second lamellar unit 7 and a third lamellar unit 8. Specifically, the thermal insulation layer 4 is formed by alternately layering and depositing second thermal barrier coating material powder and third thermal barrier coating material powder; the first thermal barrier coating material powder and the second thermal barrier coating material powder are respectively deposited to form a first sheet unit 6 and a second sheet unit 7, and the sheet density of the first sheet unit 6 and the second sheet unit 7 is larger than 90%; the third thermal barrier coating material powder is deposited to form a third lamellar unit 8, and the density of lamellae of the third lamellar unit 8 is less than 60%. The density difference between the lamellar unit 7 and the lamellar unit 8 is to form new pores at the interface, namely the pores 11 formed in high-temperature service, due to the difference of sintering shrinkage degree in high-temperature thermal exposure.
In the heat insulation layer 4, the volume of all the third lamellar units 8 is 10-50% of the total volume of all the second lamellar units 7 and all the third lamellar units 8. The lower limit of 10 percent can ensure that a certain amount of new pores are formed in high-temperature service, and the sintering resistance effect is realized; the 50% upper limit is to avoid excessive formation of high temperature service-forming voids 11, which can lead to cracking and spalling.
M layers of second lamellar units 7 are longitudinally arranged in the heat insulation layer 4 at intervals adjacent to the third lamellar unit 8 along the heat flow direction, M is a natural number, and the value range of M is 10-100. The lower limit of M is to ensure that the coating can spontaneously form certain new pores in high-temperature service so as to achieve the aim of sintering resistance; the upper limit of M is to avoid the formation of large pores by interconnecting newly formed pores, which may cause cracking and peeling of the coating.
The first sheet unit 6 and the second sheet unit 7 are formed by spreading and resolidifying powder droplets, and the size of the first sheet unit 6 and the size of the second sheet unit 7 perpendicular to the heat flow direction are 5-40 μm and the size of the second sheet unit 6 and the size of the second sheet unit 7 along the heat flow direction are 0.5-5 μm. The third lamellar unit 8 is formed by spreading a suspension containing nanoparticles, the size of the third lamellar unit is 10-300 mu m in the direction vertical to the heat flow direction, the size of the third lamellar unit is 0.5-15 mu m in the direction parallel to the heat flow direction, and the particle size of the nanoparticles is 5-200 nm.
The interlayer bonding rate of the first sheet layer unit 6 in the toughening layer 3 is not lower than 50%; the interlayer bonding rate of the adjacent second sheet unit 7 in the heat insulation layer 4 is not higher than 50%. The interlayer bonding rate of the toughening layer is not lower than 50%, so that the whole anti-cracking capability of the toughening layer can be ensured, and the bonding rate of the heat insulation layer is not higher than 50%, so that the whole heat insulation capability of the toughening layer can be ensured.
The toughening layer 3 and the heat insulation layer 4 both comprise interlayer micropores 9 and interlayer microcracks 10, the size of the interlayer micropores 9 in the direction vertical to the heat flow is 1-40 μm, the size of the interlayer micropores in the direction parallel to the heat flow is 0.01-0.5 μm, the size of the interlayer microcracks 10 in the direction vertical to the heat flow is 0.01-0.8 μm, and the size of the interlayer microcracks in the direction parallel to the heat flow is 0.5-5 μm.
Referring to fig. 3, in the service process, because the shrinkage directions of the third lamellar unit 8 and the second lamellar unit 7 are opposite, and the shrinkage degree of the loosened third lamellar unit 8 is greater than that of the second lamellar unit 7, a plurality of pores vertical to the heat flow direction are spontaneously formed at the interface of the second lamellar unit 7 and the third lamellar unit 8, namely the pores 11 formed in the high-temperature service process, the performance degradation is delayed, and the purpose of integral sintering resistance is achieved. Meanwhile, the toughening layer can improve the fracture toughness, the gradient structure and the columnar structure of the coating, and can reduce the cracking driving force of the coating in the service process, thereby achieving the purpose of long service life. And furthermore, based on the design of a double-layer gradient columnar structure, the synergistic design of the anti-sintering long-life thermal barrier coating is realized.
Example 1
Referring to fig. 1 and 2, the thermal insulation layer 4 with three sub-layers is used as an example to illustrate the preparation method of the present invention.
The invention provides a preparation method of a sintering-resistant long-life double-layer gradient columnar structure thermal barrier coating, which comprises the following steps:
step 3.1, smelting and crushing powder by adopting yttria stabilized zirconia with the particle size of 20-50 microns, and spraying by using an atmospheric plasma technology to prepare a first coating with the diameter of 25.4mm multiplied by 20 microns, wherein the first coating is formed by stacking 15-25 layers of second lamellar units 7, and the second lamellar units 7 are formed by melting second thermal barrier coating material powder, then impacting the second thermal barrier coating material powder on the toughening layer 3, and spreading and solidifying the second thermal barrier coating material powder; the size of the second slice unit 7 along the direction vertical to the heat flow is 5-40 μm, and the size along the direction parallel to the heat flow is 0.5-5 μm; a second interlayer micropore 92 is also arranged between two adjacent layers of second layer units 7, a second interlayer microcrack 102 is arranged between the second layer units 7 of the same layer, the size of the second interlayer micropore 92 in the direction vertical to the heat flow is 1-40 μm, and the size in the direction parallel to the heat flow is 0.01-0.5 μm; the size of the microcracks 102 in the second layer is 0.01-0.8 μm in the direction vertical to the heat flow and 0.5-5 μm in the direction parallel to the heat flow. The spraying power is 39kW, the main gas argon is 50L/min, the auxiliary gas hydrogen is 7L/min, the spraying distance is 60mm, and the gun moving speed is 800 mm/s;
step 3.2, spraying nano YSZ dispersion liquid with the concentration of 5mol/L by adopting a suspension liquid material spraying technology, and spraying and forming a plurality of third lamellar units 8 with the size of 10-300 mu m vertical to the heat flow direction and the size of 0.5-15 mu m parallel to the heat flow direction on the deposited first coating, wherein the spraying power is 39kW, the main argon gas is 60L/min, the auxiliary hydrogen gas is 4L/min, the spraying distance is 200mm, the gun walking speed is 1500mm/s, and the liquid flow rate is 20 mL/min;
3.3, covering a first coating on the first coating formed in the step 3.1 and the third lamellar unit 8 formed in the step 3.2 by adopting an atmospheric plasma technology, wherein the first coating comprises 15-25 layers of second lamellar units 7; the second sheet unit 7 is formed by melting the second thermal barrier coating material powder, then impacting the first coating formed in the step 3.1 and the third sheet unit 8 formed in the step 3.2, and spreading and solidifying;
and 3.4, sequentially repeating the step 3.2 to the step 3.3 until the thickness of the first sub-layer 41 reaches 140 mu m and the thermal conductivity is 1.4W/m.K.
And 4, increasing the spraying distance of the plasma spraying deposition of the second lamellar unit 7, and preparing a second sub-layer 42 of the ceramic layer on the first sub-layer 41, wherein the method specifically comprises the following steps:
step 4.1, 8YSZ with the particle size of 20-50 microns is adopted to smelt and crush powder, a first coating with the diameter of 25.4mm multiplied by 20 microns is prepared by spraying through an air plasma technology, the first coating is formed by stacking 15-25 layers of second lamellar units 7, and the second lamellar units 7 are formed by melting second thermal barrier coating material powder, then impacting the second thermal barrier coating material powder onto a first sublayer 41 and spreading and solidifying the second thermal barrier coating material powder; the size of the second slice unit 7 along the direction vertical to the heat flow is 5-40 μm, and the size along the direction parallel to the heat flow is 0.5-5 μm; a second interlayer micropore 92 is also arranged between two adjacent second sub-layer units 7, in the same layer, a second interlayer microcrack 102 is arranged between the adjacent second sub-layer units 7, the size of the second interlayer micropore 92 in the direction vertical to the heat flow is 1-40 μm, and the size in the direction parallel to the heat flow is 0.01-0.5 μm; the size of the microcracks 102 in the second layer is 0.01-0.8 μm in the direction vertical to the heat flow and 0.5-5 μm in the direction parallel to the heat flow; the spraying power is 39kW, the main gas argon is 50L/min, the auxiliary gas hydrogen is 7L/min, the spraying distance is 70mm, and the gun moving speed is 800 mm/s;
step 4.2, spraying nano YSZ dispersion liquid with the concentration of 5mol/L by adopting a suspension liquid material spraying technology, and spraying and forming a plurality of third lamellar units 8 on the deposited first coating, wherein the size of the third lamellar units 8 perpendicular to the heat flow direction is 10-300 mu m, the size parallel to the heat flow direction is 0.5-15 mu m, the spraying power is 39kW, the main argon gas is 60L/min, the auxiliary gas hydrogen is 4L/min, the spraying distance is 200mm, the gun moving speed is 1500mm/s, and the liquid flow rate is 20 mL/min;
step 4.3, covering a first coating on the first coating formed in the step 4.1 and the third lamellar unit 8 formed in the step 4.2 by adopting an atmospheric plasma technology, wherein the first coating comprises 15-25 layers of second lamellar units 7; the second sheet unit 7 is formed by melting the second thermal barrier coating material powder, then impacting the first coating formed in the step 4.1 and the third sheet unit 8 formed in the step 4.2, and spreading and solidifying;
and 4.4, sequentially repeating the step 4.2 to the step 4.3 until the total thickness of the second sub-layer 42 reaches 130 mu m and the thermal conductivity is 1.3W/m.K.
step 5.1, 8YSZ with the particle size of 20-50 microns is adopted to smelt and crush powder, a first coating with the diameter of 25.4mm multiplied by 20 microns is prepared by spraying on the second sub-layer 42 through an air plasma technology, the first coating is formed by stacking 15-25 layers of second sheet units 7, and the second sheet units 7 are formed by melting second thermal barrier coating material powder, then impacting the second sub-layer 42, and spreading and solidifying the second thermal barrier coating material powder; the size of the second slice unit 7 along the direction vertical to the heat flow is 5-40 μm, and the size along the direction parallel to the heat flow is 0.5-5 μm; and a second interlayer micropore 92 is also arranged between two adjacent layers of second layer units, in the second layer unit of the same layer, a second interlayer microcrack 102 is arranged between the adjacent second layer units 7, the size of the second interlayer micropore 92 in the direction vertical to the heat flow is 1-40 μm, the size in the direction parallel to the heat flow is 0.01-0.5 μm, the size of the in-layer microcrack 10 in the direction vertical to the heat flow is 0.01-0.8 μm, and the size in the direction parallel to the heat flow is 0.5-5 μm. The spraying power is 39kW, the main gas argon is 50L/min, the auxiliary gas hydrogen is 7L/min, the spraying distance is 80mm, and the gun moving speed is 800 mm/s;
step 5.2, spraying nano YSZ dispersion liquid with the concentration of 5mol/L by adopting a suspension liquid material spraying technology, and spraying and forming a plurality of third lamellar units 8 on the deposited first coating, wherein the size of the third lamellar units 8 perpendicular to the heat flow direction is 10-300 mu m, the size parallel to the heat flow direction is 0.5-15 mu m, the spraying power is 39kW, the main argon gas is 60L/min, the auxiliary hydrogen gas is 4L/min, the spraying distance is 200mm, the gun walking speed is 1500mm/s, and the liquid flow rate is 20 mL/min;
step 5.3, covering a first coating on the first coating formed in the step 5.1 and the third lamellar unit 8 formed in the step 5.2 by adopting an atmospheric plasma technology, wherein the first coating comprises 15-25 layers of second lamellar units 7; the second sheet unit 7 is formed by melting the second thermal barrier coating material powder, then impacting the first coating formed in the step 5.1 and the third sheet unit 8 formed in the step 5.2, and spreading and solidifying;
and 5.4, sequentially repeating the step 5.2 to the step 5.3 until the total thickness of the third sub-layer 43 reaches 120 mu m and the thermal conductivity is 1.2W/m.K.
step 6.1, heating the prepared thermal insulation layer 4 by adopting flame, and simultaneously heating the double-layer thermal barrier coating and the substrate 1 to 900 ℃ within 5 min;
and 6.2, impacting the heat insulation layer 4 by adopting strong water flow with the liquid flow speed of 5m/s and the liquid flow diameter of 0.2mm, and reducing the temperature of the heat insulation layer 4 to be below 200 ℃ within 10 s. The thermal insulation layer 4 is restrained by the matrix 1 during cooling shrinkage to generate transverse tensile stress inside the thermal insulation layer 4, so that a longitudinal slit 5 is formed.
Based on the above process, a thermal barrier coating with a double-layer gradient columnar structure is prepared, as shown in fig. 1 and 2. The thermal barrier coating comprises a toughening layer 3 and a thermal insulation layer 4, wherein the thermal insulation layer 4 is in a gradient columnar structure, the ratio of the thickness of different sub-layers to the thermal conductivity of the different sub-layers is equal, the thermal conductivity of the sub-layers decreases from the sub-layer 33 to the sub-layer 31 in an equal difference mode, and the tolerance is 0.1W/m.K.
Example 2
The difference between this example and example 1 is that the thermal spraying method used in step 1 is vacuum plasma spraying or supersonic flame spraying or cold spraying.
Example 3
The present embodiment is different from embodiment 1 in that, in step 1, the thickness of the metal bonding layer 2 is 100 μm; in the step 2, in the deposition process, the substrate 1 is preheated to 300 ℃; in the steps 3-5, the temperature of the substrate 1 is controlled not to exceed 180 ℃ in the deposition process.
Example 4
The difference between this embodiment and embodiment 1 is that, in step 1, the thickness of the metal bonding layer 2 is 125 μm; in the step 2, in the deposition process, the matrix is preheated to 500 ℃; in the steps 3 to 5, the temperature of the substrate 1 is controlled not to exceed 160 ℃ in the deposition process.
Example 5
This example differs from example 1 in that in step 4, the plasma spray deposition of the second lamellar unit 7 has a spray distance of 90mm, a total thickness of the second sublayer 42 of 110 μm and a thermal conductivity of 1.1W/m · K; in step 5, the plasma spray deposition of the second lamellar unit 7 is carried out at a spray distance of 120mm, the total thickness of the third sublayer 43 is 80 μm, and the thermal conductivity is 0.8W/m · K, i.e. the decreasing tolerance of the thermal conductivity of the sublayers is 0.3W/m · K.
Example 6
This example differs from example 1 in that only two sublayers 41 and 42 are included and in step 4 the plasma spray deposition of the second lamellar unit 7 has a spray distance of 110mm, a total thickness of the second sublayer 42 of 90 μm and a thermal conductivity of 0.9W/m.k, i.e. a decreasing thermal conductivity tolerance of the sublayers of 0.5W/m.k.
Example 7
The difference between this example and example 1 is that the concentration of the nano YSZ suspension used in steps 3-5 is 2 mol/L.
Example 8
The difference between this example and example 1 is that the concentration of the nano YSZ suspension used in steps 3-5 is 3.5 mol/L.
Example 9
The difference between the embodiment and the embodiment 1 is that in the step 6, the temperature of the heat-insulating layer 4 and the substrate is simultaneously raised to 1150 ℃ within 10min, and the retention time is not more than 2min at 900-1150 ℃.
Example 10
The difference between the embodiment and the embodiment 1 is that in the step 6, the temperature of the heat-insulating layer 4 and the substrate 1 is simultaneously raised to 1400 ℃ within 15min, and the residence time at 900-1400 ℃ is not more than 2 min.
Example 11
This example differs from example 1 in that in step 6, a strong water flow velocity of 300m/s and a water flow diameter of 5.1mm are selected.
Example 12
This example differs from example 1 in that in step 6, a strong water flow rate of 500m/s and a water flow diameter of 10mm are selected.
Claims (10)
1. A sintering-resistant long-life double-layer gradient columnar structure thermal barrier coating is characterized by comprising a toughening layer (3) and a thermal insulation layer (4) which are sequentially arranged on a metal bonding layer (2) from bottom to top; the toughening layer (3) comprises a plurality of layers of first ply units (6); the heat insulation layer (4) comprises N sub-layers, the N sub-layers comprise a first sub-layer to an N sub-layer which are sequentially arranged from bottom to top, N is a natural number within 2-20, and the heat insulation layer (4) is divided into columns by longitudinal gaps (5); the ratio of the thickness of the different sub-layers to the thermal conductivity thereof is equal, and the thermal conductivity from the first sub-layer (41) to the Nth sub-layer is decreased in an equal difference manner;
each sub-layer comprises first coating layers and third lamellar units (8) which are alternately arranged, the bottom layer of the sub-layer is the first coating layer, and the first coating layers which are not the bottom layer in the sub-layer cover the first coating layers and the third lamellar units (8) below the first coating layers; the first coating comprises a plurality of layers of second lamellar units (7); the density of the first slice unit (6) and the density of the second slice unit (7) are both larger than 90%; the density of the third lamellar unit (8) is less than 60%; the thickness of the toughening layer (3) accounts for 10-50% of the total thickness of the toughening layer (3) and the heat insulation layer (4).
2. The sintering-resistant long-life double-layer gradient columnar structure thermal barrier coating as claimed in claim 1, wherein the width of the longitudinal slit (5) in the direction perpendicular to the heat flow direction is 0.1-3% of the thickness of the thermal insulation layer (4), and the depth in the heat flow direction is 10-100% of the thickness of the thermal insulation layer (4).
3. The thermal barrier coating with the sintering-resistant long-life double-layer gradient columnar structure as claimed in claim 1, wherein M layers of second sheet units (7) are arranged between adjacent third sheet units (8) in the heat flow direction, and M is a natural number within 10-100; the volume of all the third slice units (8) is 10-50% of the total volume of all the second slice units (7) and all the third slice units (8).
4. The sintering-resistant long-life double-layer gradient columnar structure thermal barrier coating as claimed in claim 1, wherein the bonding rate between the layers of the first sheet unit (6) in the toughening layer (3) is not less than 50%; the interlayer bonding rate of the second sheet layer unit (7) in all the sub-layers in the heat insulation layer (4) is less than or equal to 50%.
5. The sintering-resistant long-life double-layer gradient columnar structure thermal barrier coating as claimed in claim 1, wherein the thermal conductivity of the first sublayer (41) to the N sublayer has a tolerance of 0.1W/m-K to 0.5W/m-K.
6. The sintering-resistant long-life double-layer gradient columnar structure thermal barrier coating as claimed in claim 1, wherein the toughening layer (3) has a first layer of inter-micro-pores (91) between two adjacent first layer units (6), and has a first layer of intra-micro-pores (101) between adjacent first layer units (6) in the same layer of first layer units; in the heat insulation layer (4), a second interlayer micropore (92) is formed between two adjacent second sheet layer units, and in the same second sheet layer unit, a second interlayer microcrack (102) is formed between two adjacent second sheet layer units (7).
7. The anti-sintering long-life double-layer gradient columnar structure thermal barrier coating as claimed in claim 1, wherein the third sheet unit (8) is arranged on the first coating at intervals, and the third sheet unit (8) covers 10-50% of the surface area of the first coating below the third sheet unit.
8. The method for preparing a sintering-resistant long-life double-layer gradient columnar structure thermal barrier coating as claimed in any one of claims 1 to 7, comprising the steps of:
step 1, depositing a metal bonding layer (2) with the thickness of 100-150 microns on a substrate (1);
step 2, depositing a first thermal barrier coating material on the metal bonding layer (2) to form a toughening layer (3);
step 3, sequentially depositing N sub-layers of the heat insulation layer (4) on the toughening layer (3) from bottom to top, and adjusting the spraying parameters to ensure that the ratio of the thickness of different sub-layers to the heat conductivity of the different sub-layers is equal, and the heat conductivity of the sub-layers decreases from the first sub-layer (41) to the Nth sub-layer in an equal difference manner; the manufacturing process of each sub-layer is the same, and the method comprises the following steps:
step 3.1, depositing a second thermal barrier coating material to form a first coating;
step 3.2, spraying a suspension of third thermal barrier coating material powder on the first coating to form a third lamellar unit (8), and then repeating the step 3.1-the step 3.2 until each sublayer reaches the designed thickness;
and 4, preparing a longitudinal gap (5) in the heat insulation layer (4) by adopting a water flow impact method, and forming a columnar structure in the heat insulation layer (4).
9. The method for preparing a sintering-resistant long-life double-layer gradient columnar structure thermal barrier coating as claimed in claim 8, wherein the step 4 comprises the following steps:
step 4.1, heating the toughening layer (3), the heat insulation layer (4) and the substrate (1) to 900-1400 ℃ within 20min at the same time, and keeping the temperature at 900-1400 ℃ for no more than 2 min;
and 4.2, adopting water flow to impact in 10s to reduce the temperature of the toughening layer (3) and the heat insulation layer (4) to be below 200 ℃.
10. The preparation method of the anti-sintering long-life double-layer gradient columnar structure thermal barrier coating as claimed in claim 8, wherein in the step 2, the substrate (1) is preheated to 300-500 ℃ in the deposition process; in step 3, the temperature of the substrate (1) is controlled not to exceed 200 ℃ during the deposition process.
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Effective date of registration: 20221206 Address after: 712046 Floor 2, Building 7, Incubation Park, Gaoke Second Road, Xianyang Hi tech Industrial Development Zone, Shaanxi Province Patentee after: Xianyang Gazelle Valley New Material Technology Co.,Ltd. Address before: 710049 No. 28 West Xianning Road, Shaanxi, Xi'an Patentee before: XI'AN JIAOTONG University |