Gradient anti-oxidation coating based on rare earth alloying modification

Abstract

The invention relates to the field of gradient coatings, in particular to a gradient anti-oxidation coating based on rare earth alloying modification. The rare earth alloying system disclosed by the invention is (HfB2-HfSi2-La2O3) MA-SiC, and the rare earth alloying system disclosed by the invention is a rare earth alloying system. By constructing the stable Hf-La-Si-O multiphase glass layer, the problems that when a conventional system rapidly forms a SiO2 barrier, the viscosity is low, volatilization is prone to occurring, and the stable sealing effect is difficult to achieve are solved, so that the glass barrier sealing oxygen resistance is strengthened, and the dynamic stability of the gradient anti-oxidation coating is guaranteed. Meanwhile, based on the rare earth alloying modification effect, the refractory La / Hf oxide is embedded into the glass layer, the pinning effect is strengthened, and the advantage of inhibiting crack diffusion is shown.

Description

Technical Field

[0001] The invention relates to the field of gradient coatings, in particular to a gradient anti-oxidation coating based on rare earth alloying modification. Background Art

[0002] In recent years, HfB 2 -Silicon-based coatings have attracted much attention for their excellent antioxidant properties. During the high-temperature protection process, they can generate a composite glass layer after oxidation, which can repair surface defects while forming a dense and compact sealing layer, forming a gradient antioxidant structure with the original coating to resist oxygen penetration. With the rapid development of aerospace materials, antioxidant materials are expanding to higher working environments, and the original working environment can no longer meet the increasingly updated application needs. However, when the working environment exceeds 1650℃, the harsh oxidation environment under ultra-high temperature will degrade the dynamic stability of the gradient antioxidant, causing the oxygen barrier structure to be rapidly destroyed, seriously affecting the antioxidant protection effect of the coating.

[0003] Zhang Menglin et al. disclosed a ZrB-based 2 Non-equilibrium alloying modified high oxygen barrier coating and preparation method (Chinese patent, application number: 202110416686.2), using transition metal silicide MoSi 2 Phase powder alloying improves ZrB 2 Phase distribution uniformity is aimed at improving its anti-oxidation ability in an ultra-high temperature environment of 1700℃ after coating. Although transition metal silicides can quickly form SiO in situ in the initial stage of oxidation 2 barrier, forming a gradient anti-oxidation coating structure to alleviate oxygen corrosion, but in this state, SiO 2 The barrier has low viscosity and is easy to volatilize, making it difficult to exert a stable sealing effect, resulting in limited antioxidant protection of the gradient coating. Therefore, there is an urgent need for a gradient coating antioxidant layer that can provide stable protection in an ultra-high temperature environment and a preparation method thereof. Summary of the invention

[0004] The present invention aims to provide a gradient anti-oxidation coating based on rare earth alloying modification and a preparation method thereof, and solves the problem of the conventional system rapidly forming SiO by constructing a stable Hf-La-Si-O multiphase glass layer. 2 When forming a barrier, problems such as low viscosity, easy volatilization, and difficulty in achieving a stable sealing effect are overcome, thereby strengthening the glass barrier sealing oxygen barrier and ensuring the dynamic stability of the gradient anti-oxidation coating.

[0005] In order to achieve the above technical purpose, the technical solution provided by the present invention is as follows:

[0006] A gradient anti-oxidation coating based on rare earth alloying modification, wherein the gradient coating anti-oxidation layer based on rare earth alloying modification has a rare earth alloying system of (HfB 2 -HfSi 2 -La 2 O 3 ) MA -SiC.

[0007] As an improvement, the rare earth alloying system volume ratio range of the gradient coating anti-oxidation layer based on rare earth alloying modification is: HfB 2 :HfSi 2 :La 2 O 3 :SiC=47.4:12:0.6:40~47.85:12:0.15:40.

[0008] The present invention also discloses a method for preparing a gradient anti-oxidation coating based on rare earth alloying modification, which is carried out according to the following steps:

[0009] S1. Hf, B, Si and La 2 O 3 As raw materials, HfB was prepared by mechanical mixing and self-propagating combustion synthesis method. 2 -HfSi 2 -La 2 O 3 Powder;

[0010] S2. The ground HfB 2 -HfSi 2 -La 2 O 3 The powder is mixed with SiC powder to prepare (HfB 2 -HfSi 2 -La 2 O 3 ) MA -SiC gradient coating anti-oxidation layer powder source;

[0011] (3) Use (HfB 2 -HfSi 2 -La 2 O 3 ) MA -SiC gradient coating anti-oxidation layer powder source, using low temperature hot pressing technology to densify the coating on the substrate surface, to prepare (HfB 2 -HfSi 2 -La 2 O 3 ) MA -SiC rare earth alloy modified gradient coating anti-oxidation layer.

[0012] As an improvement, Hf, B, Si, La described in step S1 2 O 3 The molar ratio range of the powder is: Hf:B:Si:La 2 O 3 =100:173.44:26.56:0.1~100:173.22:26.78:0.39

[0013] As an improvement, the HfB described in step S2 2 -HfSi 2 -La 2 O 3 Powder volume ratio range: HfB 2 :HfSi 2 :La 2 O 3 =79:20:1~79.75:20:0.25.

[0014] As an improvement, the (HfB 2 -HfSi 2 -La 2 O 3 ) MA -SiC gradient coating anti-oxidation layer powder source volume ratio range is: HfB 2 :HfSi 2 :La 2 O 3 :SiC=47.4:12:0.6:40~47.85:12:0.15:40.

[0015] The advantages of the present invention are:

[0016] The present invention utilizes rare earth oxide alloying modified (HfB 2 -HfSi 2 -La 2 O 3 ) MA -SiC coating system can generate a stable Hf-La-Si-O composite glass layer by in-situ oxidation on the surface of the anti-oxidation layer, overcoming the problem of the conventional system in the rapid formation of SiO 2 At the same time, based on the rare earth alloying modification effect, refractory La / Hf oxides are embedded in the glass layer, which enhances the pinning effect and shows the advantage of inhibiting crack propagation. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1This is a cross-sectional microscopic morphology of the gradient coating anti-oxidation layer based on rare earth alloying modification obtained in Example 1 of the present invention.

[0018] Figure 2 This is a cross-sectional microscopic morphology of the gradient coating anti-oxidation layer based on rare earth alloying modification obtained in Example 2 of the present invention.

[0019] Figure 3 This is a cross-sectional microscopic morphology of the gradient coating anti-oxidation layer based on rare earth alloying modification obtained in Example 3 of the present invention.

[0020] Figure 4 This is a cross-sectional microscopic morphology of the conventional gradient coating anti-oxidation layer obtained in Comparative Example 1 of the present invention.

[0021] Figure 5 The 1700°C oxidation weight gain curves of the gradient coating anti-oxidation layer obtained in Examples 1 to 3 of the present invention and Comparative Example 1. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments.

[0023] Example 1

[0024] This embodiment discloses a gradient anti-oxidation coating based on rare earth alloying modification and a preparation method thereof.

[0025] The rare earth alloying system of the gradient coating anti-oxidation layer involved in this embodiment is (HfB 2 -HfSi 2 -La 2 O 3 ) MA -SiC. Among them, the volume ratio of the rare earth alloying system is: HfB 2 -HfSi 2 -La 2 O 3 -SiC=47.85:12:0.15:40.

[0026] The preparation method of this embodiment comprises the following steps:

[0027] S1. Hf, B, Si and La 2 O 3 As raw materials, HfB was prepared by mechanical mixing and self-propagating combustion synthesis method. 2 -HfSi 2 -La 2 O3 Powder; in this embodiment, Hf, B, Si, La 2 O 3 The molar ratio of the powder is: Hf:B:Si:La 2 O 3 =100:173.44:26.56:0.1; HfB 2 -HfSi 2 -La 2 O 3 The volume ratio of the powder is: HfB 2 :HfSi 2 :La 2 O 3 =79.75:20:0.25.

[0028] S2. The ground HfB 2 -HfSi 2 -La 2 O 3 The powder is mixed with SiC powder to prepare (HfB 2 -HfSi 2 -La 2 O 3 ) MA -SiC gradient coating anti-oxidation layer powder source; among them, HfB 2 -HfSi 2 -La 2 O 3 The volume ratio of powder to SiC powder is 60:40, and the final product is (HfB 2 -HfSi 2 -La 2 O 3 ) MA -The volume ratio of SiC powder source is: HfB 2 :HfSi 2 :La 2 O 3 :SiC=47.85:12:0.15:40.

[0029] (3) Use (HfB 2 -HfSi 2 -La 2 O 3 ) MA -SiC gradient coating anti-oxidation layer powder source, using low temperature hot pressing technology to densify the coating on the substrate surface, to prepare (HfB 2 -HfSi 2 -La 2 O 3 ) MA-SiC rare earth alloy modified gradient coating anti-oxidation layer.

[0030] This embodiment provides a preferred ratio of a gradient anti-oxidation coating based on rare earth alloying modification and a preparation method thereof, wherein the cross-sectional morphology and oxidation weight gain curve are as follows: Figure 3 , Figure 5 As shown in the figure, it can be seen that the gradient coating anti-oxidation layer based on rare earth alloying modification provided in this embodiment has a low weight gain after high-temperature oxidation at 1700°C, showing a good oxidation penetration inhibition effect.

[0031] Embodiment 2:

[0032] This embodiment discloses a gradient anti-oxidation coating based on rare earth alloying modification and a preparation method thereof.

[0033] The rare earth alloying system of the gradient coating anti-oxidation layer involved in this embodiment is (HfB 2 -HfSi 2 -La 2 O 3 ) MA -SiC. Among them, the volume ratio of the rare earth alloying system is: HfB 2 -HfSi 2 -La 2 O 3 -SiC=47.7:12:0.3:40.

[0034] The preparation method of this embodiment comprises the following steps:

[0035] S1. Hf, B, Si and La 2 O 3 As raw materials, HfB was prepared by mechanical mixing and self-propagating combustion synthesis method. 2 -HfSi 2 -La 2 O 3 Powder; in this embodiment, Hf, B, Si, La 2 O 3 The molar ratio of the powder is: Hf:B:Si:La 2 O 3 =100:173.37:26.63:0.19; HfB 2 -HfSi 2 -La 2 O 3 The volume ratio of the powder is: HfB 2 :HfSi 2 :La 2 O 3 =79.5:20:0.5.

[0036] S2. The ground HfB 2 -HfSi 2 -La 2 O 3 The powder is mixed with SiC powder to prepare (HfB 2 -HfSi 2 -La 2 O 3 ) MA -SiC gradient coating anti-oxidation layer powder source; among them, HfB 2 -HfSi 2 -La 2 O 3 The volume ratio of powder to SiC powder is 60:40, and the final product is (HfB 2 -HfSi 2 -La 2 O 3 ) MA -The volume ratio of SiC powder source is: HfB 2 :HfSi 2 :La 2 O 3 :SiC=47.7:12:0.3:40.

[0037] (3) Use (HfB 2 -HfSi 2 -La 2 O 3 ) MA -SiC gradient coating anti-oxidation layer powder source, using low temperature hot pressing technology to densify the coating on the substrate surface, to prepare (HfB 2 -HfSi 2 -La 2 O 3 ) MA -SiC rare earth alloy modified gradient coating anti-oxidation layer.

[0038] This embodiment provides a preferred ratio of a gradient anti-oxidation coating based on rare earth alloying modification and a preparation method thereof, wherein the cross-sectional morphology and oxidation weight gain curve are as follows: Figure 2 , Figure 5 As shown in the figure, it can be seen that the gradient coating anti-oxidation layer based on rare earth alloying modification provided in this embodiment has a low weight gain after high-temperature oxidation at 1700°C, showing a good oxidation penetration inhibition effect.

[0039] Embodiment 3:

[0040] This embodiment discloses a gradient anti-oxidation coating based on rare earth alloying modification and a preparation method thereof.

[0041] The rare earth alloying system of the gradient coating anti-oxidation layer involved in this embodiment is (HfB 2 -HfSi 2 -La 2 O 3 ) MA -SiC. Among them, the volume ratio of the rare earth alloying system is: HfB 2 -HfSi 2 -La 2 O 3 -SiC=47.4:12:0.6:40.

[0042] The preparation method of this embodiment comprises the following steps:

[0043] S1. Hf, B, Si and La 2 O 3 As raw materials, HfB was prepared by mechanical mixing and self-propagating combustion synthesis method. 2 -HfSi 2 -La 2 O 3 Powder; in this embodiment, Hf, B, Si, La 2 O 3 The molar ratio of the powder is: Hf:B:Si:La 2 O 3 =100:173.22:26.78:0.39; HfB 2 -HfSi 2 -La 2 O 3 The volume ratio of the powder is: HfB 2 :HfSi 2 :La 2 O 3 =79:20:1.

[0044] S2. The ground HfB 2 -HfSi 2 -La 2 O 3 The powder is mixed with SiC powder to prepare (HfB 2 -HfSi 2 -La 2 O 3 ) MA -SiC gradient coating anti-oxidation layer powder source; among them, HfB 2 -HfSi 2 -La 2 O 3 The volume ratio of powder to SiC powder is 60:40, and the final product is (HfB2 -HfSi 2 -La 2 O 3 ) MA -The volume ratio of SiC powder source is: HfB 2 :HfSi 2 :La 2 O 3 :SiC=47.4:12:0.6:40.

[0045] (3) Use (HfB 2 -HfSi 2 -La 2 O 3 ) MA -SiC gradient coating anti-oxidation layer powder source, using low temperature hot pressing technology to densify the coating on the substrate surface, to prepare (HfB 2 -HfSi 2 -La 2 O 3 ) MA -SiC rare earth alloy modified gradient coating anti-oxidation layer.

[0046] This embodiment provides a preferred ratio of a gradient anti-oxidation coating based on rare earth alloying modification and a preparation method thereof, wherein the cross-sectional morphology and oxidation weight gain curve are as follows: Figure 1 , Figure 5 As shown in the figure, it can be seen that the gradient coating anti-oxidation layer based on rare earth alloying modification provided in this embodiment has a low weight gain after high-temperature oxidation at 1700°C, showing a good oxidation penetration inhibition effect.

[0047] Comparative Example 1:

[0048] The gradient coating anti-oxidation layer involved in this comparative example is a conventional gradient coating anti-oxidation layer without rare earth alloying modification inside, and its system is (HfB 2 -HfSi) MA -SiC, the volume ratio is: 48:12:40, which is carried out according to the following steps:

[0049] A method for preparing the above conventional gradient coating anti-oxidation layer comprises:

[0050] (1) Hf, B, and Si were used as raw materials (the molar ratio of Hf, B, and Si powders was: Hf:B:Si=100:173.51:26.49), and HfB was prepared by self-propagating combustion synthesis after mechanical mixing. 2 -HfSi 2 Powder.

[0051] (2) The polished HfB2 -HfSi 2 Powder (volume ratio is HfB 2 :HfSi 2 =80:20) mixed with SiC powder to prepare (HfB 2 -HfSi 2 ) MA -SiC conventional gradient coating anti-oxidation layer powder source.

[0052] (3) Use (HfB 2 -HfSi 2 ) MA -SiC conventional gradient coating anti-oxidation layer powder source (volume ratio is HfB 2 :HfSi 2 :SiC=48:12:40), and the coating was densified on the substrate surface by low temperature hot pressing technology to prepare (HfB 2 -HfSi 2 ) MA -SiC conventional gradient coating anti-oxidation layer.

[0053] This comparative example provides a conventional gradient coating anti-oxidation layer and a preparation method thereof, wherein the cross-sectional morphology and oxidation weight gain curve are respectively as follows: Figure 4 , Figure 5 As shown in the figure, it can be seen that since there is no rare earth alloying modification inside the coating of Comparative Example 1, although the transition metal silicide can quickly form SiO in situ in the initial stage of oxidation, 2 barrier, forming a gradient anti-oxidation coating structure to alleviate oxygen corrosion, but in this state, SiO 2 The barrier viscosity is low, it is easy to volatilize, and it is difficult to exert a stable sealing effect, resulting in limited antioxidant protection of the gradient coating, showing an overall higher oxidation weight gain curve. Compared with the examples, examples 1 to 3 play a role in (HfB 2 -HfSi 2 -La 2 O 3 ) MA -The rare earth alloying modification in the SiC coating system can generate a stable Hf-La-Si-O composite glass layer on the surface of the anti-oxidation layer by in-situ oxidation, which can form an effective gradient anti-oxidation structure with the anti-oxidation layer, overcoming the conventional system's rapid formation of SiO 2 It overcomes a series of problems as a barrier, shows good oxidation penetration inhibition effect, and has a low oxidation weight gain curve, which ensures the dynamic stability of the gradient anti-oxidation coating.

[0054] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A gradient anti-oxidation coating based on rare earth alloying modification, characterized in that: The rare earth alloying modified gradient coating anti-oxidation layer has a rare earth alloying system of (HfB2-HfSi2-La2O3) MA -SiC.

2. A gradient anti-oxidation coating based on rare earth alloying modification according to claim 1, characterized in that: The volume ratio range of the rare earth alloying system of the gradient coating anti-oxidation layer based on rare earth alloying modification is: HfB2:HfSi2:La2O3:SiC=47.4:12:0.6:40~47.85:12:0.15:

40.

3. A method for preparing a gradient anti-oxidation coating based on rare earth alloying modification as described above, characterized in that: Follow these steps: S1. Using Hf, B, Si and La2O3 as raw materials, mechanically mixing and using self-propagating combustion synthesis method to prepare HfB2-HfSi2-La2O3 powder; S2. Mix the ground HfB2-HfSi2-La2O3 powder with SiC powder to prepare (HfB2-HfSi2-La2O3) MA -SiC gradient coating anti-oxidation layer powder source; (3) Use (HfB2-HfSi2-La2O3) MA -SiC gradient coating anti-oxidation layer powder source, using low temperature hot pressing technology to densify the coating on the substrate surface to prepare (HfB2-HfSi2-La2O3) MA -SiC rare earth alloy modified gradient coating anti-oxidation layer.

4. The method for preparing a gradient anti-oxidation coating based on rare earth alloying modification according to claim 3, characterized in that: The molar ratio range of the Hf, B, Si and La2O3 powders described in step S1 is: Hf:B:Si:La2O3=100:173.44:26.56:0.1~100:173.22:26.78:0.

39.

5. The method for preparing a gradient anti-oxidation coating based on rare earth alloying modification according to claim 3, characterized in that: The volume ratio range of the HfB2-HfSi2-La2O3 powder described in step S2 is: HfB2:HfSi2:La2O3=79:20:1~79.75:20:0.

25.

6. The method for preparing a gradient anti-oxidation coating based on rare earth alloying modification according to claim 3, characterized in that: (HfB2-HfSi2-La2O3) as described in step S3 MA -The volume ratio range of the powder source of the anti-oxidation layer of the SiC gradient coating is: HfB2:HfSi2:La2O3:SiC=47.4:12:0.6:40~47.85:12:0.15:40.

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