Double-rare-earth crystal inhibition reinforced modified ultra-high-temperature protective coating as well as preparation method and application thereof

Abstract

The invention relates to a double-rare-earth crystal inhibition reinforced modified ultra-high-temperature protective coating as well as a preparation method and application thereof. The preparation method comprises the following steps: preparing a CVD-SiC inner coating on the surface of a matrix material by adopting a chemical vapor deposition method; a slurry sintering method is adopted, and a double rare earth (DRE) doped silicon-based structure anti-oxidation middle layer is prepared on the surface of the CVD-SiC inner coating; and preparing the PVD-ZrC thermal ablation prevention outer coating on the rare earth doped silicon-based anti-oxidation layer by adopting a physical vapor deposition method. According to the SiC / dRe coated Si-ZrSi2-ZrB2 / ZrC coating provided by the invention, the crystallization growth of SiO2-TGO in a silicon-based component structure is inhibited by doping rare earth oxide (REO) and / or rare earth carbide (REC), so that the stress accumulation and thermal expansion mismatch effect of the coating in a thermal service process is greatly relieved. Meanwhile, the complementary advantages of silicon-based ceramic and ultra-high-temperature ceramic in the aspects of oxidation resistance and ablation resistance are fully combined, the thermal protection capacity of the coating under the ultra-high-temperature condition is improved, the service life of the coating is remarkably prolonged, and the service stability of the coating is remarkably improved.

Description

Technical Field

[0001] The invention belongs to the technical field of thermal protection of carbon-based or ceramic-based composite materials, and in particular relates to a composite coating with a long-life protection function and a preparation method and application thereof. Background Art

[0002] Future new space equipment will put forward more stringent requirements on the service performance of carbon / carbon (C / C) composite materials under ultra-high temperature conditions. Focusing on the development of highly reliable and long-life ultra-high temperature protective coatings is an effective way to improve the service stability of C / C composite materials. In order to solve the problems of high-temperature intrinsic oxidation and thermal ablation faced by C / C composite materials, research has shown that by fully combining the performance advantages of silicon-based ceramics and ultra-high temperature ceramics (UHTC), it is expected to develop ultra-high temperature anti-oxidation and anti-ablation protective coatings with excellent comprehensive performance. Among them, the composite structure of transition bonding layer-silicon-based ceramic oxygen barrier layer-UHTC anti-ablation layer has been proven to be the most promising coating solution that can maintain good anti-oxidation and anti-ablation performance. However, during the thermal service process, the amorphous SiO2 with high self-healing and low oxygen permeability formed by the oxidation of silicon-based ceramics is prone to crystallization phase change and seriously damages the thermal mismatch performance of the coating, which in turn leads to a decrease in the service stability of the coating system and the sustainability of ultra-high temperature thermal protection. Therefore, seeking to improve the structural compatibility and phase structure stability of the silicon-based ceramic intermediate oxygen barrier layer by inhibiting the crystallization of amorphous SiO2 in the coating is an important technical basis for ensuring the stability, reliability and long life of the coating system under ultra-high temperature service.

[0003] Through past research, the inventors also observed the formation of a SiO2-TGO growth layer near the silicon carbide interface layer at 1400°C. The cracks in the distribution area increased significantly, and the SiC coating showed obvious thinning, cracking and buckling damage, which greatly increased the risk of failure of the coating system. Amorphous SiO2 is prone to crystallization and transformation into quartz at high temperatures. The essence of this is that the local medium-range ordered structure of amorphous SiO2 is similar to the dynamic disordered structure of β-quartz, accompanied by a large volume effect, which causes cracking, weak self-healing, and weakened thermal protection capabilities of the silicon-based coating material, greatly reducing the overall service life and reliability of the coating system. In view of the fact that the traditional design concept has failed to propose an effective solution to the problem of inhibiting the growth of SiO2-TGO in the coating, this has become a significant obstacle to the material obtaining long-life thermal protection in a high-temperature oxidizing environment. To this end, it is urgent to explore and construct a new system and innovative structure of the coating based on the traditional coating design thinking, aiming to fundamentally solve the problem of thermal mismatch of the coating caused by the growth of SiO2-TGO. Summary of the invention

[0004] In view of the above problems, the present invention provides a double rare earth crystal suppression strengthened modified ultra-high temperature protective coating and its preparation method and application, which effectively improves the stable thermal protection capability of carbon-based or ceramic-based composite materials under high temperature service conditions.

[0005] The above purpose can be achieved through the following technical solutions:

[0006] In the first aspect, the present invention provides a double rare earth crystal suppression strengthened modified ultra-high temperature protective coating, including a CVD-SiC inner coating prepared on the surface of a substrate material, a double rare earth (DRE) doped silicon-based structured anti-oxidation intermediate layer (dRe@Si-ZrSi2-ZrB2) prepared on the CVD-SiC inner coating, and a PVD-ZrC outer coating prepared on the intermediate layer.

[0007] The double rare earth doped silicon-based structure anti-oxidation dRe@Si-ZrSi2-ZrB2 coating comprises a doping phase of rare earth oxide (REO) and / or rare earth carbide (REC), and a Si-ZrSi2-ZrB2 composite ceramic phase.

[0008] Preferably, the thickness of the CVD-SiC inner coating is 20 to 50 μm; the thickness of the dRe@Si-ZrSi2-ZrB2 intermediate layer is 80 to 150 μm; and the thickness of the PVD-ZrC outer coating is 10 to 30 μm.

[0009] Preferably, the thickness of the CVD-SiC inner coating is 20 μm; the thickness of the dRe@Si-ZrSi2-ZrB2 intermediate layer is 120 μm; and the thickness of the PVD-ZrC outer coating is 12 μm.

[0010] In a second aspect, the present invention provides a method for preparing the above-mentioned antioxidant composite coating, comprising the steps of S1: preparing a CVD-SiC inner coating on the surface of a substrate material by a chemical vapor deposition method, so as to improve the physicochemical compatibility between the outer coating layer / substrate material, and simultaneously providing a primary antioxidant barrier for the substrate material during the coating preparation process of step S2; S2: preparing a double rare earth doped silicon-based structure antioxidant dRe@Si-ZrSi2-ZrB2 intermediate layer on the surface of the CVD-SiC inner coating by a slurry sintering method combined with an oxygen-assisted heat treatment process, wherein the amorphous SiO2, borosilicate and other glassy media produced by the layer are the key to maintaining good thermal protection performance of the coating; S3: preparing a double rare earth doped silicon-based structure antioxidant dRe@Si-ZrSi2-ZrB2 intermediate layer on the surface of the CVD-SiC inner coating by a magnetron sputtering method; 2- A PVD-ZrC layer is prepared on the ZrB2 intermediate layer. This design of a multi-layer composite coating and a rare earth doping inhibition strategy can ensure that the coating has better protection for the substrate under ultra-high temperature service conditions, thereby achieving long-life service of the C / C composite material in an ultra-high temperature environment.

[0011] In a further embodiment of the present invention, S1 specifically includes the steps of: surface processing a fiber-reinforced carbon-based or ceramic-based composite material (C / C, C / SiC, SiC / SiC, C / SiCN, etc.) to keep it flat, cleaning and drying it; placing the pretreated substrate sample into a chemical vapor deposition furnace, using trichloromethylsilane (MTS) as a liquid precursor, H2 as a reaction gas, Ar as a dilution gas, and H2 as a carrier gas assisted by MTS bubbling gasification and transport; during the deposition process, the reaction pressure is controlled to be 900-2000 Pa, the MTS heating temperature is 30-50°C, the reaction temperature is 900-1250°C, and the reaction time is 15-30 hours.

[0012] In a further embodiment of the present invention, S2 specifically includes the following steps: S201: any two combinations of rare earth oxides (CeO2, Y2O3, La2O3, Yb2O3, Ho2O3 and HfO2, etc.) and / or rare earth carbides (CeC2, LaC2, NdC2, etc.) are used as double rare earth dopants, and the rare earth dopants with a mass fraction of 5-25% are added to the Si-ZrSi2-ZrB2 mixed powder and ground finely and evenly. The mixed powder after doping and grinding is added to a 3-6wt% polyvinyl alcohol / ethanol dispersant, and stirred continuously at room temperature for 6-12 hours to form a slurry, wherein the mass fraction of Si powder is 5-22%, the mass fraction of ZrSi2 is 28-54%, and the mass fraction of ZrB2 is 24-67%; S202: brush or cold spray the slurry onto the surface of the CVD-SiC inner coating, and perform oxygen-assisted pre-oxidation heat treatment after drying. The dried coating sample was placed on the Y2O3 layer powder and placed in an atmosphere reactor for densification sintering. The nitrogen flow rate was controlled at 50-80 ml min -1 , oxygen flow rate is 10~50ml·min -1 , the heat treatment temperature is 1100~1400℃, and the constant temperature pre-oxidation heat treatment time is 0.5~3 hours.

[0013] In a further embodiment of the present invention, S3 specifically includes the steps of: fixing the coating sample treated by S2 on the copper back plate of the sample holder at the top of the magnetron sputtering reaction chamber, and using a high-purity C target and a Zr target excited by DC to deposit PVD-ZrC on the sample surface. During the implementation process, the C target power is 90-130W, the Zr target power is 60-100W, the substrate temperature is 100-300°C, the deposition pressure is 0.3-2Pa, the Ar flow rate is 10-70sccm, the sample rotation speed is 5-30rpm, the target sputtering distance is 80-150mm, and the deposition time is 20-60 hours.

[0014] It should be noted that in order to prevent some REO from forming rare earth silicates with SiO2, a rare earth inhibitor with high field strength, high coordination and high accumulation effect on amorphous SiO2 can usually be used to carry out crystallization inhibition research of silicon-based structural coatings. In the high-temperature inhibition and strengthening process, the inhibition effect can be controlled by optimizing the composition, content and particle size of the double rare earth doping material.

[0015] In a third aspect, the present invention provides a long-life application of the above-mentioned double rare earth crystal suppression and strengthening modified ultra-high temperature protective coating in achieving crystal suppression and strengthening of silicon-based ceramic thermal protective coating.

[0016] The technical solution provided by the present invention has the following beneficial effects:

[0017] (1) Aiming at the failure problems caused by the crystallization of amorphous SiO2 and the growth of TGO on the interface in the silicon-based coating structure, the present invention proposes a new method for inhibiting the crystallization of amorphous SiO2 by inhibiting the transformation of amorphous SiO2 to crystallized quartz under thermal environment conditions by rare earth doping, thereby slowing down the growth of TGO in the coating. The crystallization of the silicon-based structure coating is inhibited by means of rare earth inhibitors with high field strength, high coordination and high accumulation effects on amorphous SiO2, so as to achieve high structural compatibility and phase structure stability of the silicon-based structure in the coating, and overcome the failure problems such as cracks, interface separation and delamination caused by the growth of SiO2-TGO in the coating under high temperature and long-term service.

[0018] (2) The present invention fully combines the performance advantages of silicon-based ceramics and UHTC, and is expected to develop a high-temperature thermal protective coating with excellent comprehensive performance. It also further improves the crystallization inhibition theory of amorphous SiO2 in silicon-based protective coatings, which has important engineering application value for achieving long life and high reliability of C / C composite materials under extreme service conditions and the development of new silicon-based ceramic coatings.

[0019] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the coating structure of the present invention.

[0021] Figure 2 This is a schematic diagram of the oxygen-assisted pre-oxidation heat treatment device of the present invention.

[0022] Figure 3 This is the stress distribution diagram of Y2O3@Si-ZrSi2-ZrB2 ceramics with different doping states after oxidation prepared by hot isostatic pressing technology. DETAILED DESCRIPTION

[0023] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present invention.

[0024] The experimental methods in the following examples are conventional methods unless otherwise specified. The experimental materials used in the following examples are purchased from conventional reagent manufacturers unless otherwise specified. Any parameters can be increased or decreased in proportion according to actual conditions.

[0025] Embodiment 1

[0026] This embodiment provides a double rare earth crystal suppression strengthened modified ultra-high temperature protective coating, the matrix material is a carbon fiber reinforced carbon-based composite material (C / C), including a CVD-SiC inner coating with a thickness of 30μm; a dRe@Si-ZrSi2-ZrB2 intermediate layer with a thickness of 150μm; and a PVD-ZrC outer coating with a thickness of 17μm.

[0027] The preparation method comprises the following steps:

[0028] Substrate pretreatment: The density is 1.74cm 3 / g C / C composite material is processed into 10×10×10mm 3 The block was polished and ground with 400-mesh and 800-mesh sandpaper for 1 hour respectively, and then ultrasonically cleaned in anhydrous ethanol, acetone and deionized water, and dried for later use.

[0029] S1: First, the pretreated C / C block samples were evenly distributed on the graphite rack and placed in the core reaction zone of the chemical vapor deposition furnace. Then, the input flow rates of H2 carrier gas, H2 reaction gas and Ar dilution gas were controlled by mass flow meters to be 48L / h, 60L / h and 360L / h, respectively, and the corresponding MTS heating temperature was 35℃ and the gasification input flow rate was 110g / h. The heating temperature and carrier gas flow rate of MTS were controlled to achieve the input flow rate of gasified MTS. The difference in the flow rate of each gas will lead to differences in the deposition reaction kinetics and the self-shaped structure and thermophysical properties of CVD-SiC. Further, by adjusting the opening of the solenoid valve on the exhaust pipeline to 35%, maintaining the pressure in the furnace at 1100-1200Pa, the reaction temperature at 1100℃, and the deposition time at 15 hours, a CVD-SiC inner coating with a thickness of about 30μm was finally obtained.

[0030] S2: First, according to the mass ratio of Y2O3:CeC2=3:1, the two powders were weighed as double rare earth dopants. In addition, according to the mass ratio of Si:ZrSi2:ZrB2=0.18:0.44:0.38, the three powders were weighed into a mortar, and an additional rare earth dopant with a mass ratio of 10wt.% was added and finely ground for 2 hours to obtain a Y2O3-CeC2@Si-ZrSi2-ZrB2 mixed filler. Then, a polyvinyl butyral / ethanol dispersant with a mass fraction of 3wt% was prepared, 20wt.% of the mixed filler was added to the dispersant, and stirred continuously at room temperature for 12 hours to obtain a Y2O3-CeC2@Si-ZrSi2-ZrB2 slurry. Finally, the Y2O3-CeC2@Si-ZrSi2-ZrB2 intermediate layer was prepared by brushing on the surface of the CVD-SiC inner coating of the C / C composite material to 150μm, and dried at 90℃ for 3 hours. In order to prevent adhesion during the pre-oxidation sintering process, the dried sample was placed on the Y2O3 layer powder and then transferred to the oxygen-assisted pre-oxidation heat treatment furnace. Heat treatment process: heating to 950℃ at 5℃ / min, keeping warm for 30 minutes; heating to 1200℃ at 3℃ / min, keeping warm for 1.5 hours; cooling to 500℃ at 8℃ / min, and cooling to room temperature with the furnace. The entire oxygen-assisted heat treatment process controlled the N2 input flow rate to 70ml / min and the O2 flow rate to 30ml / min, and finally obtained the double rare earth modified Y2O3-CeC2@Si-ZrSi2-ZrB2 coating with densification sintering.

[0031] S3: First, use high-temperature adhesive to fix the prepared intermediate layer coating sample on the copper back plate of the sample holder at the top of the magnetron sputtering reaction chamber, heat the sample holder to 300℃ at 5℃ / min and keep constant temperature, adjust the speed to 15rpm, and the sputtering distance to 115mm. Before formal deposition, only the Zr target is turned on for deposition to improve the bonding strength of the coating, control the ignition pressure to 2Pa, the Ar flow rate to 50sccm, and the ignition sputtering time to 5min. Then, a high-purity C target and a Zr target excited by DC are used to deposit PVD-ZrC on the sample surface at the same time, control the C target power and the Zr target power to 100W and 90W respectively, the deposition pressure to 0.8Pa, and the continuous deposition time to 32 hours, so that the thickness of the PVD-ZrC outer coating reaches about 17μm, and then SiC / Y2O3-CeC2@Si-ZrSi2-ZrB2 / ZrC is obtained. In the entire coating system, PVD-ZrC serves as an anti-thermal ablation layer; Y2O3-CeC2@Si-ZrSi2-ZrB2 is a silicon-based anti-oxidation layer, which suppresses the formation and growth of SiO2-TGO at high temperatures by adjusting the doping amounts of Y2O3 and CeC2, thereby achieving its crystal inhibition and strengthening effect; the inner layer CVD-SiC serves as a buffer layer.

[0032] Embodiment 2

[0033] This embodiment provides a double rare earth crystal suppression strengthened modified ultra-high temperature protective coating, the matrix material of which is a carbon fiber reinforced SiCN ceramic matrix composite material (C / SiCN), including a CVD-SiC inner coating with a thickness of 20μm; a dRe@Si-ZrSi2-ZrB2 intermediate layer with a thickness of 120μm; and a PVD-ZrC outer coating with a thickness of 12μm.

[0034] The preparation method comprises the following steps:

[0035] Substrate pretreatment: The density is 2.01cm 3 / g C / C composite material is processed into 10×10×10mm 3 The block was polished and ground with 400-mesh and 800-mesh sandpaper for 1 hour respectively, and then ultrasonically cleaned in anhydrous ethanol, acetone and deionized water, and dried for later use.

[0036] S1: First, the pretreated C / C block samples were evenly distributed on the graphite rack and placed in the core reaction zone of the chemical vapor deposition furnace. Then, the input flow rates of H2 carrier gas, H2 dilution gas and Ar protective gas were controlled by mass flow meters to be 30L / h, 58L / h and 224L / h, respectively, and the corresponding MTS heating temperature was 40°C and the gasification input flow rate was 80g / h. Further, by adjusting the opening of the solenoid valve on the exhaust pipeline to 22%, maintaining the pressure in the furnace at 900-1100Pa, the reaction temperature at 1100°C, and the deposition time for 15 hours, a CVD-SiC inner coating with a thickness of about 20μm was finally obtained.

[0037] S2: First, according to the mass ratio of Y2O3:CeO2=4:1, the two powders were weighed as double rare earth dopants. In addition, according to the mass ratio of Si:ZrSi2:ZrB2=0.22:0.46:0.32, the three powders were weighed into a mortar, and an additional rare earth dopant with a mass ratio of 8wt.% was added and finely ground for 2 hours to obtain a Y2O3-CeO2@Si-ZrSi2-ZrB2 mixed filler. Then, a polyvinyl butyral / ethanol dispersant with a mass fraction of 3.5wt% was prepared, 20wt.% of the mixed filler was added to the dispersant, and stirred continuously at room temperature for 12 hours to obtain a Y2O3-CeO2@Si-ZrSi2-ZrB2 slurry. Finally, the Y2O3-CeO2@Si-ZrSi2-ZrB2 intermediate layer was prepared by brushing on the surface of the CVD-SiC inner coating of the C / C composite material to 120μm, and dried at 90℃ for 3 hours. In order to prevent adhesion during the pre-oxidation sintering process, the dried sample was placed on the Y2O3 layer powder and then transferred to the oxygen-assisted pre-oxidation heat treatment furnace. Heat treatment process: heating to 950℃ at 5℃ / min, keeping warm for 30 minutes; heating to 1300℃ at 3℃ / min, keeping warm for 1 hour; cooling to 500℃ at 8℃ / min, and cooling to room temperature with the furnace. The entire oxygen-assisted heat treatment process controlled the N2 input flow rate to 80ml / min and the O2 flow rate to 20ml / min, and finally obtained the double rare earth modified Y2O3-CeO2@Si-ZrSi2-ZrB2 coating with densification sintering.

[0038] S3: First, use high-temperature adhesive to fix the prepared intermediate layer coating sample on the copper back plate of the sample holder at the top of the magnetron sputtering reaction chamber, heat the sample holder to 250℃ at 5℃ / min and keep constant temperature, adjust the speed to 20rpm, and the sputtering distance to 95mm. Before formal deposition, only the Zr target is turned on for deposition to improve the bonding strength of the coating, control the ignition pressure to 2Pa, the Ar flow rate to 30sccm, and the ignition sputtering time to 5min. Then, a high-purity C target and a Zr target excited by DC are used to deposit PVD-ZrC on the sample surface at the same time, control the C target power and the Zr target power to 100W and 70W respectively, the deposition pressure to 0.6Pa, and the continuous deposition time to 40 hours, so that the thickness of the PVD-ZrC outer coating reaches about 12μm, and then SiC / Y2O3-CeO2@Si-ZrSi2-ZrB2 / ZrC is obtained.

[0039] Embodiment 3

[0040] This embodiment provides a double rare earth crystal suppression strengthened modified ultra-high temperature protective coating, the matrix material of which is a carbon fiber reinforced SiC ceramic matrix composite material (C / SiC), including a CVD-SiC inner coating with a thickness of 50μm; a dRe@Si-ZrSi2-ZrB2 intermediate layer with a thickness of 80μm; and a PVD-ZrC outer coating with a thickness of 25μm.

[0041] The preparation method comprises the following steps:

[0042] Substrate pretreatment: The density is 1.98cm 3 / g C / SiC composite material is processed into 10×10×10mm 3 The block was polished and ground with 400-mesh and 800-mesh sandpaper for 1 hour respectively, and then ultrasonically cleaned in anhydrous ethanol, acetone and deionized water, and dried for later use.

[0043] S1: First, the pretreated C / C block samples were evenly distributed on the graphite rack and placed in the core reaction zone of the chemical vapor deposition furnace. Then, the input flow rates of H2 carrier gas, H2 dilution gas and Ar protective gas were controlled by mass flow meters to be 60L / h, 48L / h and 330L / h, respectively, and the corresponding MTS heating temperature was 45°C and the gasification input flow rate was 150g / h. Further, by adjusting the opening of the solenoid valve on the exhaust pipeline to 30%, maintaining the pressure in the furnace at 1400-1500Pa, the reaction temperature at 1200°C, and the deposition time for 22 hours, a CVD-SiC inner coating with a thickness of about 50μm was finally obtained.

[0044] S2: First, according to the mass ratio of Yb2O3:CeC2=4:1, the two powders were weighed as double rare earth dopants. In addition, according to the mass ratio of Si:ZrSi2:ZrB2=0.20:0.52:0.28, the three powders were weighed into a mortar, and an additional rare earth dopant with a mass ratio of 8wt.% was added and finely ground for 2 hours to obtain a Yb2O3-CeC2@Si-ZrSi2-ZrB2 mixed filler. Then, a polyvinyl butyral / ethanol dispersant with a mass fraction of 5wt% was prepared, 20wt.% of the mixed filler was added to the dispersant, and it was continuously stirred at room temperature for 6 hours to obtain a Yb2O3-CeC2@Si-ZrSi2-ZrB2 slurry. Finally, the Yb2O3-CeC2@Si-ZrSi2-ZrB2 intermediate layer was brushed on the surface of the CVD-SiC inner coating of the C / C composite material to 80μm, and dried at 90℃ for 3 hours. In order to prevent adhesion during the pre-oxidation sintering process, the dried sample was placed on the Y2O3 layer powder and then transferred to the oxygen-assisted pre-oxidation heat treatment furnace. Heat treatment process: heating to 950℃ at 5℃ / min, keeping warm for 30 minutes; heating to 1100℃ at 3℃ / min, keeping warm for 0.5 hours; cooling to 500℃ at 8℃ / min, and cooling to room temperature with the furnace. The entire oxygen-assisted heat treatment process controlled the N2 input flow rate to 50ml / min and the O2 flow rate to 50ml / min, and finally obtained the double rare earth modified Yb2O3-CeC2@Si-ZrSi2-ZrB2 coating with densification sintering.

[0045] S3: First, use high-temperature adhesive to fix the prepared intermediate layer coating sample on the copper back plate of the sample holder at the top of the magnetron sputtering reaction chamber, heat the sample holder to 100°C at 5°C / min and keep constant temperature, adjust the speed to 25rpm, and the sputtering distance to 105mm. Before formal deposition, only the Zr target is turned on for deposition to improve the bonding strength of the coating, control the ignition pressure to 2Pa, the Ar flow rate to 70sccm, and the ignition sputtering time to 5min. Then, PVD-ZrC is deposited on the sample surface using a high-purity C target and a Zr target excited by DC at the same time, and the C target power and the Zr target power are controlled to be 110W and 90W respectively, the deposition pressure is 1.0Pa, and the continuous deposition time is 44 hours, so that the thickness of the PVD-ZrC outer coating reaches about 25μm, thereby obtaining SiC / Yb2O3-CeC2@Si-ZrSi2-ZrB2 / ZrC.

[0046] The SiC / dRe@Si-ZrSi2-ZrB2 / ZrC coatings prepared in Examples 1 to 3 of the present invention were subjected to high temperature oxidation and SiO2-TGO growth thickness tests, and the specific results are shown in Table 1 below:

[0047] Table 1. Statistics of test results of SiC / dRe@Si-ZrSi2-ZrB2 / ZrC coating

[0048] Example Embodiment 1 Embodiment 2 Embodiment 3 1400℃ / 150h oxidation weight loss rate (%) 0.57 -1.14 -0.89 <![CDATA[Interface SiO2-TGO growth thickness (μm)]]> 7～13 - 5～8

[0049] It should be noted that, in addition to the parameters in the preparation process involved in the above-mentioned embodiments 1 to 3, it is also feasible to select other preparation parameters.

[0050] The numerical values ​​mentioned in the embodiments of the present invention are only exemplary, and the remaining numerical values ​​also belong to the present invention; the steps involved in the embodiments of the present invention are not sequential, so changing the order of the steps also belongs to the scope of the present invention. It should be noted that, unless otherwise specified, the professional terms involved in the present invention should be the technical workers in this field.

Claims

1. A double rare earth crystal suppression strengthened modified ultra-high temperature protective coating, characterized in that: The method comprises preparing a CVD-SiC inner coating on the surface of a substrate material, preparing a double rare earth (DRE) doped silicon-based structured anti-oxidation intermediate layer (dRe@Si-ZrSi2-ZrB2) on the CVD-SiC inner coating, and preparing a PVD-ZrC outer coating on the intermediate layer; The double rare earth doped silicon-based structure anti-oxidation dRe@Si-ZrSi2-ZrB2 coating comprises a doping phase of rare earth oxide (REO) and / or rare earth carbide (REC), and a Si-ZrSi2-ZrB2 composite ceramic phase.

2. The double rare earth crystal suppression strengthened modified ultra-high temperature protective coating according to claim 1, characterized in that: The thickness of the CVD-SiC inner coating is 20 to 50 μm; the thickness of the dRe@Si-ZrSi2-ZrB2 intermediate layer is 80 to 150 μm; and the thickness of the PVD-ZrC outer coating is 10 to 30 μm.

3. A method for preparing the double rare earth crystal suppression strengthened modified ultra-high temperature protective coating according to claim 1 or 2, characterized in that: Use the following steps: S1: Prepare CVD-SiC inner coating on the surface of substrate material by chemical vapor deposition method; S2: Using slurry sintering method, a double rare earth doped silicon-based structured anti-oxidation dRe@Si-ZrSi2-ZrB2 intermediate layer was prepared on the surface of CVD-SiC inner coating; S3: Prepare the PVD-ZrC layer on the dRe@Si-ZrSi2-ZrB2 intermediate layer by magnetron sputtering.

4. The method for preparing the double rare earth crystal suppression strengthened modified ultra-high temperature protective coating according to claim 3, characterized in that: The S1 step includes: surface processing of fiber-reinforced carbon-based or ceramic-based composite materials (C / C, C / SiC, SiC / SiC, C / SiCN, etc.) to keep it flat, cleaning and drying; placing the pretreated substrate sample into a chemical vapor deposition furnace, using trichloromethylsilane (MTS) as a liquid precursor, hydrogen (H2) as a reaction gas, argon (Ar) as a diluent gas, and H2 as a carrier gas assisted by MTS bubbling gasification and transportation; during the deposition process, the H2 carrier gas is controlled to be 30-60L / h, the H2 reaction gas is 48-80L / h, the Ar diluent gas is 220-450L / h, the reaction pressure is 900-2000Pa, the MTS heating temperature is 30-50°C, the reaction temperature is 900-1250°C, and the reaction time is 15-30 hours.

5. The method for preparing the double rare earth crystal suppression strengthened modified ultra-high temperature protective coating according to claim 3, characterized in that: The S2 specifically comprises the steps of: S201: using any two combinations of rare earth oxides (CeO2, Y2O3, La2O3, Yb2O3, Ho2O3 and HfO2, etc.) and / or rare earth carbides (CeC2, LaC2, NdC2, etc.) as double rare earth dopants, adding 5-25% of the added rare earth dopant by mass into Si-ZrSi2-ZrB2 mixed powder and grinding it finely and evenly, adding the mixed powder after doping and grinding into 3-6wt.% polyvinyl alcohol / ethanol dispersant, and stirring continuously at room temperature for 6-12 hours to form a slurry; The mass fraction of Si powder is 5-22%, the mass fraction of ZrSi2 is 28-54%, and the mass fraction of ZrB2 is 24-67%; S202: brushing or cold spraying the slurry onto the surface of the CVD-SiC inner coating, and performing oxygen-assisted pre-oxidation heat treatment after drying; The dried coating sample was placed on the Y2O3 layer powder and placed in an atmosphere reactor for densification sintering. The nitrogen flow rate was controlled at 50-80 ml min. -1 , oxygen flow rate is 10~50ml·min -1 , the heat treatment temperature is 1100~1400℃, and the constant temperature pre-oxidation heat treatment time is 0.5~3 hours.

6. The method for preparing the double rare earth crystal suppression strengthened modified ultra-high temperature protective coating according to claim 3, characterized in that: The step S3 comprises: fixing the coating sample processed in S2 on the copper back plate of the sample holder at the top of the magnetron sputtering reaction chamber, and performing PVD-ZrC deposition on the sample surface using a high-purity C target and a Zr target excited by direct current; The C target power is 90-130 W, the Zr target power is 60-100 W, the substrate temperature is 100-300°C, the deposition pressure is 0.3-2 Pa, the Ar flow rate is 10-70 sccm, the sample rotation speed is 5-30 rpm, the target sputtering distance is 80-150 mm, and the deposition time is 20-60 hours.

7. The double rare earth crystal suppression and strengthening modified ultra-high temperature protective coating according to claim 1 or 2 is used to achieve long-life application of crystal suppression and strengthening of silicon-based ceramic thermal protective coating.

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