A coating for extending the high temperature service life of a metal component and applications

Abstract

The application relates to a coating prolonging the high-temperature service life of a metal component and application, in particular to a coating which is composed of a high-entropy alloy intermediate layer, an oxidation-resistant layer, an oxygen-blocking layer and a heat-insulating layer in sequence, the high-entropy alloy intermediate layer is composed of seven or more elements and has an ordered L12 crystal structure, the oxidation-resistant layer is composed of a Pt-containing metal parent phase with an ordered L12 crystal structure and a small amount of alumina nanoparticles, the oxygen-blocking layer is alumina, and the heat-insulating layer is composed of nano lanthanum phosphate and nano yttria-stabilized zirconia. The coating is applied to the heated surface of a component, including but not limited to the surface of components such as an aero-engine combustion chamber, a turbine and a nozzle, and plays the roles of oxidation resistance, heat insulation, ablation resistance, high-temperature corrosion resistance and erosion resistance. The application has the advantages that the allowable temperature of a part can be increased to 1500 DEG C, the high-temperature creep life of the protected part is not damaged, the heat insulation temperature is increased by more than one time compared with common thermal barrier coatings, and the service life is increased by more than 20 times.

Description

Technical Field

[0001] This invention relates to ultra-high temperature protection technology for metal surfaces, specifically a coating and its application for extending the high-temperature service life of metal components. Background Technology

[0002] When metallic materials are heated, they undergo high-temperature damage phenomena such as oxidation, ablation, high-temperature corrosion, and high-temperature erosion. To reduce these damages, internal cavity cooling or back-side cooling methods can be used to lower the temperature of the parts. Applying a high-temperature protective coating to the surface of components to protect them and extend their service life is also a common technical measure. Known high-temperature protective coatings include metallic coatings, non-metallic coatings, and metallic-non-metallic composite coatings. The combination of the above cooling and coating techniques has promoted the development of thermal barrier coatings (TBCs). These TBCs involve applying a low thermal conductivity high-temperature protective coating to the surface of a part while simultaneously employing internal cavity cooling techniques, further significantly reducing the metal surface temperature by 50-300°C. Thermal barrier coatings are now widely used in advanced industrial products, such as core components of aero engines, industrial and marine gas turbines, and rocket engines.

[0003] Current industry-standard thermal barrier coatings consist of an adhesive layer and a ceramic top layer. The ceramic top layer material is typically yttrium partially stabilized zirconia (YSZ), while the adhesive layer material is typically MCrAlY (M = Ni, Co, or a combination thereof) or platinum aluminum (β-NiPtAl). During service, a thermally grown oxide (TGO), typically alumina, spontaneously forms at the interface between the adhesive layer and the ceramic layer.

[0004] When the applied component material is a single-crystal nickel-based superalloy and the component metal temperature exceeds 1000℃, the service life of components coated with existing industry-standard thermal barrier coatings exhibits a dramatic decrease. Based on a 1000℃ service life benchmark, the coating lifespan at 1050, 1100, 1150, and 1200℃ is 40%, 15%, 6%, and 3%, respectively. The main reasons for this dramatic decrease in component service life are: severe interdiffusion between the coating and substrate damages the substrate, softening of the adhesive layer, and a significant increase in the coating oxidation rate leading to the peeling off of the insulation layer. Summary of the Invention

[0005] To avoid the problem of a significant decrease in the service life of components, this invention adopts a new coating structure and materials, expanding the application range of thermal barrier coatings and significantly extending the service life of the protected parts:

[0006] 1) The traditional adhesive layer is replaced by a double-layer structure consisting of a high-strength and highly compatible intermediate layer and a low-expansion optimized anti-oxidation layer, thereby avoiding the problems of coating-substrate interdiffusion damage, adhesive layer softening, and a significant increase in coating oxidation rate.

[0007] 2) The traditional YSZ ceramic layer is replaced with a double-layer structure of oxygen barrier layer and low oxygen permeability ultra-low thermal conductivity insulation layer, which simultaneously and significantly reduces the surface temperature and surface oxidation rate of the anti-oxidation layer.

[0008] The uses of this invention are as follows:

[0009] The coating can be applied to the heated surfaces of components, including but not limited to the surfaces of components such as aerospace engine combustion chambers, turbines, and nozzles, to provide anti-oxidation, heat insulation, anti-ablation, high-temperature corrosion resistance, and erosion resistance.

[0010] The purpose of this invention is to provide new thermal barrier coating materials and structures, mainly to solve the problem that when the applied component material is a single-crystal nickel-based high-temperature alloy and the ambient temperature exceeds 1500°C, the service life of components coated with existing industrial standard thermal barrier coatings will decrease dramatically. It can also be used to replace all applications of existing industrial standard thermal barrier coatings.

[0011] The main principle of this invention:

[0012] 1) A dual-layer structure consisting of a high-entropy alloy interlayer and an anti-oxidation layer replaces the traditional adhesive layer, separating the low-diffusion and anti-oxidation functions. Interdiffusion between the high-entropy alloy interlayer and the substrate does not lead to new phases or recrystallization, thus avoiding the harmful effects of interdiffusion while retaining the high bonding strength advantages generated by it. Both the high-entropy alloy interlayer and the anti-oxidation layer adopt an ordered L12 crystal structure and employ high-entropy and noble metal strengthening measures to enhance high-temperature strength and solve the softening problem. The anti-oxidation layer is mainly composed of Ni, Al, and Pt. The addition of a small amount of Hf makes its anti-oxidation performance superior to β-NiPtAl. Doping with alumina nanoparticles reduces the difference in thermal expansion coefficients between the coating and the ceramic, lowering thermal stress and extending the coating's anti-oxidation lifespan.

[0013] 2) Replacing the traditional YSZ ceramic layer with a dual-layer structure consisting of an oxygen barrier layer and a low-oxygen-permeability thermal insulation layer enhances both oxygen barrier and thermal insulation functions. The oxygen barrier layer, made of alumina, reduces the oxygen partial pressure on the surface of the anti-oxidation layer, extending the coating's lifespan. The thermal conductivity of the low-oxygen-permeability thermal insulation layer is less than half that of the YSZ layer, and its oxygen permeability is less than an order of magnitude lower. Simultaneously, it significantly reduces the surface temperature and oxygen partial pressure of the anti-oxidation layer, making a crucial contribution to extending the lifespan of the protected parts and the coating itself.

[0014] The technical solution of this invention is:

[0015] A coating for extending the high-temperature service life of metal components comprises, in sequence, a high-entropy alloy intermediate layer (A), an anti-oxidation layer (B), an oxygen barrier layer (C), and a heat insulation layer (D), as follows: Figure 1 As shown. Among them,

[0016] A high-entropy alloy intermediate layer (A) is characterized by: an ordered L12 crystal structure composed of 7 or more chemical elements, with a thickness of 0.01–0.2 mm. The optimized chemical composition by mass percentage is: 6–12 Cr, 0.1–3 Ta, 8–11 Al, 6–15 Co, 2–5 (two or more of Re, W, and Mo), with the balance being Ni, and a thickness of 0.02–0.06 mm.

[0017] The antioxidant layer (B) is characterized by being composed of an ordered L12 crystal structure containing a Pt-containing metallic matrix (E) and a small amount of alumina nanoparticles (F), with a thickness of 0.01–0.1 mm. The optimized chemical composition of the matrix (E) is as follows (molar percentage): 25–30 Al, 10–25 Pt, 0.005–0.02 Hf, with the balance being Ni; the volume percentage of the alumina nanoparticles (F) is 0.1–5, and the thickness is 0.02–0.06 mm.

[0018] The oxygen barrier layer (C) is characterized in that it is aluminum oxide and has a thickness of 0.0005 to 0.002 mm.

[0019] The heat insulation layer (D) is characterized by being composed of nano-lanthanum phosphate (G) and nano-yttrium oxide-stabilized zirconium oxide (YSZ) (H), with a thickness of 0.1–1.5 mm. The volume percentage of nano-lanthanum phosphate (G) is 30–70%, the molar percentage of yttrium oxide in nano-YSZ (H) is 3.5–4.2%, and the optimized thickness is 0.15–0.30 mm.

[0020] The application of the coating that extends the high-temperature service life of metal components is to coat the heated surfaces of the components, including but not limited to the surfaces of components such as aerospace engine combustion chambers, turbines, and nozzles, and to provide anti-oxidation, heat insulation, anti-ablation, high-temperature corrosion resistance, and erosion resistance.

[0021] Compared with the prior art, the advantages of this invention are:

[0022] It can be used in new applications where existing industrial standard thermal barrier coatings are not applicable, including but not limited to core hot-end components of ultra-high temperature advanced engines, with a maximum allowable temperature of 1500℃. It can replace all applications of existing industrial standard thermal barrier coatings, increasing the thermal insulation temperature by more than 100% and the service life by more than 20 times. Attached Figure Description

[0023] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments:

[0024] Figure 1 A schematic diagram of a coating used to extend the high-temperature service life of metal components;

[0025] In the diagram, 1 is the heat insulation layer (D), 2 is the oxygen barrier layer (C), 3 is the anti-oxidation layer (B), 4 is the high-entropy alloy intermediate layer (A), and 5 is the component. Detailed Implementation

[0026] Implementing the coating of this invention requires the following two steps: 1) Pre-treating the surface to be sprayed to remove contaminants that may affect the coating quality, and protecting surfaces that cannot be sprayed to prevent them from being coated. 2) Sequentially preparing a high-entropy alloy intermediate layer (A), an antioxidant layer (B), an oxygen barrier layer (C), and a heat insulation layer (D) on the surface to be sprayed, from the substrate outwards.

[0027] The high-entropy alloy intermediate layer (A) has a thickness of 0.01–0.2 mm and an ordered L12 crystal structure. Its chemical composition includes five elements: Ni, Cr, Ta, Al, and Co, and two or more elements: Re, W, and Mo. The mass percentage is: 6–12 Cr, 0.1–3 Ta, 8–11 Al, 6–15 Co, 2–5 (two or more elements: Re, W, and Mo), with the balance being Ni.

[0028] The antioxidant layer (B), with a thickness of 0.01–0.1 mm, is composed of an ordered L12 crystal structure containing a Pt-containing metal matrix (E) and a small amount of alumina nanoparticles (F). The chemical composition of the matrix (E) is as follows: 25–30 Al, 10–25 Pt, 0.005–0.02 Hf, with the balance being Ni. The volume percentage of the alumina nanoparticles (F) is 0.1–5%.

[0029] The oxygen barrier layer (C), with a thickness of 0.0005–0.002 mm, is made of aluminum oxide.

[0030] The heat insulation layer (D), with a thickness of 0.1 to 1.5 mm, is composed of nano-lanthanum phosphate (G) and nano-yttrium oxide stabilized zirconium oxide (referred to as nano-YSZ)(H). The volume percentage of nano-lanthanum phosphate (G) is 30 to 70, and the molar percentage of yttrium oxide in nano-YSZ(H) is 3.5 to 4.2%.

[0031] The present invention will be further described in detail below with reference to the embodiments, wherein the comparative samples include blank alloy samples and coated alloy samples (coated with a platinum-aluminum bonding layer / YSZ thermal barrier coating, the coating thickness being comparable to that of the samples of the present invention):

[0032] Example 1

[0033] The component is a turbine blade made of 6th generation single-crystal TMS-238, with a coating applied to the flow channel surface. The high-entropy alloy intermediate layer has a thickness of 0.06 mm and a chemical composition by mass percentage of 8Cr-1Ta-1Re-1Mo-1W-8Al-10Co-Ni balance. The anti-oxidation layer has a thickness of 0.04 mm, and the parent phase chemical composition by molar percentage is 30Al-25Pt-0.01Hf-Ni balance. The alumina nanoparticles (F) have a volume percentage of 5%, the oxygen barrier layer has a thickness of 0.0015 mm, the heat insulation layer has a thickness of 0.3 mm, the lanthanum phosphate nanoparticles (G) have a volume percentage of 60%, and the yttrium oxide molar percentage in the nano-YSZ (H) is 3.9–4.2%.

[0034] The bonding strength of the samples tested in the furnace was not less than 40 MPa. Thermal conductivity at 800-1400℃: the sample of this invention was not greater than 0.5 W / m·K, while the comparative coated alloy sample was not greater than 1 W / m·K. Thermal shock life (hot end 1400~1450℃, cold end 800~1000℃, heating time 20s): the sample of this invention withstood at least 3000 cycles, while the comparative coated alloy sample with a maximum of 140 cycles. Cyclic oxidation (1150℃ for 1 hour per cycle, natural atmospheric cooling): the sample of this invention showed no peeling after 500 cycles, with a weight gain not greater than 0.3 mg / cm², while the comparative coated alloy sample began to peel after a maximum of 20 cycles. Creep fracture life (800℃ / 735 MPa): blank alloy sample 1150h, sample of this invention 1145h, comparative coated alloy sample 115h.

[0035] Example 2

[0036] The component is a turbine blade made of fourth-generation single-crystal TMS138, with a coating applied to the flow channel surface. The high-entropy alloy intermediate layer has a thickness of 0.05 mm and a chemical composition by mass percentage of 6Cr-2Ta-0.5Re-2Mo-11Al-6Co-Ni balance. The anti-oxidation layer has a thickness of 0.03 mm and a parent phase chemical composition by molar percentage of 25Al-20Pt-0.01Hf-Ni balance. The alumina nanoparticles (F) have a volume percentage of 3%. The oxygen barrier layer has a thickness of 0.0015 mm, the heat insulation layer has a thickness of 0.25 mm, the lanthanum phosphate nanoparticles (G) have a volume percentage of 60%, and the yttrium oxide molar percentage in the nano-YSZ (H) is 3.9–4.2%.

[0037] The tested samples exhibited the following characteristics: adhesion strength not less than 40 MPa; thermal conductivity not greater than 0.5 W / m·K at 800-1400℃; thermal shock life (hot end 1300-1350℃, cold end 850-1050℃, heating time 20s) not less than 3000 cycles; and no coating peeling after 500 cycles of cyclic oxidation (1150℃ for 1 hour per cycle, natural atmospheric cooling), with a weight gain not greater than 0.3 mg / cm². Creep fracture life (1100℃ / 137 MPa) was 390 h for the blank alloy sample, 398 h for the sample of this invention, and 56 h for the comparative coated alloy sample.

[0038] Example 3

[0039] The components are turbine blades made of second-generation single-crystal CMSX-4 or René N5, with a coating applied to the flow channel surface. The high-entropy alloy intermediate layer has a thickness of 0.03 mm and a chemical composition by mass percentage of 8Cr-2Ta-0.5Re-2Mo-10Al-9Co-Ni balance. The anti-oxidation layer has a thickness of 0.03 mm and a parent phase chemical composition by molar percentage of 20Al-20Pt-0.01Hf-Ni balance. The alumina nanoparticles (F) have a volume percentage of 2%. The oxygen barrier layer has a thickness of 0.001 mm, the thermal insulation layer has a thickness of 0.3 mm, the nano-lanthanum phosphate (G) has a volume percentage of 60%, and the yttrium oxide molar percentage in nano-YSZ (H) is 3.9–4.2%.

[0040] The tested samples exhibited the following characteristics: adhesion strength not less than 40 MPa; thermal conductivity not greater than 0.5 W / m·K at 800-1400℃; thermal shock life (hot end 1250-1300℃, cold end 800-1000℃, heating time 20s) not less than 3000 cycles; and no coating peeling after 500 cycles of cyclic oxidation (1150℃ for 1 hour per cycle, natural atmospheric cooling), with a weight gain not greater than 0.3 mg / cm². Creep fracture life (982℃ / 206 MPa) was 201 h for the blank René N5 alloy sample, 210 h for the sample of this invention, and 135 h for the comparative coated alloy sample.

[0041] Example 4

[0042] The component is a turbine blade made of first-generation single-crystal PWA1483, with a coating applied to the flow channel surface. The high-entropy alloy intermediate layer has a thickness of 0.02 mm and a chemical composition by mass percentage of 12Cr-3Ta-1W-2Mo-10Al-9Co-Ni balance. The anti-oxidation layer has a thickness of 0.03 mm and a parent phase chemical composition by molar percentage of 30Al-10Pt-0.01Hf-Ni balance. The alumina nanoparticles (F) have a volume percentage of 3%. The oxygen barrier layer has a thickness of 0.001 mm, the heat insulation layer has a thickness of 0.15 mm, the nano-lanthanum phosphate (G) has a volume percentage of 50%, and the yttrium oxide molar percentage in nano-YSZ (H) is 3.9–4.2%.

[0043] The samples tested in the furnace showed a bonding strength of not less than 40 MPa, a thermal conductivity of not more than 0.5 W / m·K at 800-1400℃, a thermal shock life (hot end 1100~1150℃, cold end 750~950℃, heating time 20s) of not less than 3000 cycles, and no coating peeling after 500 cycles of cyclic oxidation (1100℃ for 1 hour per cycle, natural atmospheric cooling), with a weight gain of not more than 0.3 mg / cm2.

[0044] Example 5

[0045] The part is a guide vane made of cast high-temperature alloy K38G, with a coating applied to the flow channel surface. The thickness of the high-entropy alloy intermediate layer is 0.02 mm, and the chemical composition by mass percentage is 12Cr-1Ta-1W-1Mo-11Al-15Co-Ni balance. The thickness of the anti-oxidation layer is 0.03 mm, and the chemical composition of the parent phase by molar percentage is 30Al-10Pt-0.01Hf-Ni balance. The volume percentage of alumina nanoparticles (F) is 3%. The thickness of the oxygen barrier layer is 0.0005 mm, the thickness of the heat insulation layer is 0.4 mm, the volume percentage of nano-lanthanum phosphate (G) is 45%, and the molar percentage of yttrium oxide in nano-YSZ (H) is 3.9-4.2%.

[0046] For samples tested in the furnace, the bonding strength should be no less than 40 MPa, the thermal conductivity at 800-1400℃ should be no more than 0.5 W / m·K, the thermal shock life (hot end 1050~1100℃, cold end 700~900℃, heating time 20s) should be no less than 3000 cycles, and the coating should not peel off after 500 cycles of cyclic oxidation (each cycle 1000℃ holding for 1h, natural atmospheric cooling). The weight gain should be no more than 0.3 mg / cm2.

[0047] Example 6

[0048] The component is a combustion chamber assembly made of wrought high-temperature alloy GH4199, with a coating applied to the flow channel surface. The high-entropy alloy intermediate layer has a thickness of 0.02 mm and a chemical composition by mass percentage of 12Cr-3Ta-2W-3Mo-11Al-6Co-Ni balance. The anti-oxidation layer has a thickness of 0.03 mm and a parent phase chemical composition by molar percentage of 30Al-10Pt-0.01Hf-Ni balance. The alumina nanoparticles (F) have a volume percentage of 0.1%. The oxygen barrier layer has a thickness of 0.0005 mm, the heat insulation layer has a thickness of 0.5 mm, the nano-lanthanum phosphate (G) has a volume percentage of 30%, and the yttrium oxide molar percentage in nano-YSZ (H) is 3.9–4.2%.

[0049] The samples tested in the furnace showed a bonding strength of not less than 40 MPa, a thermal conductivity of not more than 0.5 W / m·K at 800-1400℃, a thermal shock life (hot end 1050~1100℃, cold end 500~700℃, heating time 20s) of not less than 3000 cycles, and no coating peeling after 500 cycles of cyclic oxidation (1000℃ for 1 hour per cycle, natural atmospheric cooling), with a weight gain of not more than 0.3 mg / cm2.

[0050] Example 7

[0051] The component is a flat plate assembly made of deformed high-temperature alloy, with a coating applied to the heated surface. The high-entropy alloy intermediate layer has a thickness of 0.02 mm and a chemical composition by mass percentage of 10Cr-2Ta-1W-1Mo-10Al-6Co-Ni balance. The anti-oxidation layer has a thickness of 0.03 mm and a parent phase chemical composition by molar percentage of 30Al-10Pt-0.01Hf-Ni balance. The alumina nanoparticles (F) have a volume percentage of 5%. The oxygen barrier layer has a thickness of 0.0005 mm, the heat insulation layer has a thickness of 1.5 mm, the lanthanum phosphate nanoparticles (G) have a volume percentage of 30%, and the yttrium oxide molar percentage in the nano-YSZ (H) is 3.9–4.2%.

[0052] The samples tested in the furnace showed a bonding strength of not less than 40 MPa. After 500 cycles of cyclic oxidation (holding at 950℃ for 1 hour per cycle and then cooling under natural atmosphere), no coating peeling was observed, and the weight gain was not greater than 0.3 mg / cm2.

[0053] Example 8

[0054] The parts are irregularly shaped components made of deformed high-temperature alloys, with a coating applied to the heated surfaces. The high-entropy alloy intermediate layer has a thickness of 0.02 mm and a chemical composition by mass percentage of 6Cr-2Ta-1W-1Mo-8Al-6Co-Ni balance. The anti-oxidation layer has a thickness of 0.03 mm and a parent phase chemical composition by molar percentage of 25Al-10Pt-0.01Hf-Ni balance. The alumina nanoparticles (F) have a volume percentage of 5%. The oxygen barrier layer has a thickness of 0.0005–0.002 mm, the thermal insulation layer has a thickness of 0.5–1.5 mm, the nano-lanthanum phosphate (G) has a volume percentage of 30%, and the yttrium oxide molar percentage in nano-YSZ (H) is 3.9–4.2%.

[0055] The samples tested in the furnace showed a bonding strength of not less than 40 MPa. After 500 cycles of cyclic oxidation (holding at 950℃ for 1 hour per cycle and then cooling under natural atmosphere), no coating peeling was observed, and the weight gain was not greater than 0.3 mg / cm2.

[0056] The above description is merely a preferred embodiment of the present invention and should not be construed as limiting the scope of the invention. Therefore, various corresponding changes and modifications made based on the technical solutions and concepts of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A coating for extending the high temperature service life of a metal component, characterized by: From bottom to top, it is composed of high-entropy alloy intermediate layer (A), oxidation-resistant layer (B), oxygen barrier layer (C) and thermal insulation layer (D) in turn; The high-entropy alloy intermediate layer (A) has ordered L12 crystal structure, is composed of seven or more chemical elements, and has a thickness of 0.01-0.2 mm; the seven or more chemical elements are CrTaAlCoMNi, wherein M is two or more of Re, W and Mo. The oxidation-resistant layer (B) is composed of a Pt-containing metal parent phase (E) with ordered L12 crystal structure and alumina nanoparticles (F), and has a thickness of 0.01-0.1 mm; the chemical composition of the parent phase (E) is Al, Pt, Hf and the balance of Ni.

2. The coating for extending the high temperature service life of a metal component according to claim 1, wherein: The oxygen barrier layer (C) is alumina, and has a thickness of 0.0005-0.002 mm.

3. The coating for extending the high temperature service life of a metal component according to claim 1, wherein: The thermal insulation layer (D) is composed of nano lanthanum phosphate (G) and nano yttria-stabilized zirconia (H), and has a thickness of 0.1-1.5 mm.

4. The coating for extending the high temperature service life of a metal component according to claim 1, wherein: The high-entropy alloy intermediate layer (A) has a mass percentage of 6-12 Cr, 0.1-3 Ta, 8-11 Al, 6-15 Co, 2-5 M and the balance of Ni, and has a thickness of 0.02-0.06 mm.

5. The coating for extending the high temperature service life of a metal component according to claim 1, wherein The parent phase (E) of the oxidation-resistant layer (B) has a molar percentage of 25-30 Al, 10-25 Pt, 0.005-0.02 Hf and the balance of Ni, and the alumina nanoparticles (F) have a volume percentage of 0.1-5, and the thickness is 0.02-0.06 mm.

6. The coating for extending the high temperature service life of a metal member according to claim 3, wherein: In the thermal insulation layer (D), the nano lanthanum phosphate (G) has a volume percentage of 30-70, and the nano yttria-stabilized zirconia (H) has a molar percentage of 3.5-4.2 of yttria, and the thickness is 0.15-0.30 mm.

7. Use of a coating to extend the high temperature service life of a metal component according to claim 1, characterized in that: It is coated on the heated surface of a component, including but not limited to the surface of an aero-engine combustion chamber, a turbine, a nozzle assembly, and has the effects of oxidation resistance, thermal insulation, ablation resistance, high-temperature corrosion resistance and erosion resistance.

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