CN116239399A - Rare earth doped binary boride modified gradient oxygen barrier coating and preparation method thereof - Google Patents
Rare earth doped binary boride modified gradient oxygen barrier coating and preparation method thereof Download PDFInfo
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- 239000011248 coating agent Substances 0.000 title claims abstract description 126
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- 229910052760 oxygen Inorganic materials 0.000 title claims abstract description 105
- 239000001301 oxygen Substances 0.000 title claims abstract description 105
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- 229910052761 rare earth metal Inorganic materials 0.000 title claims abstract description 91
- 150000002910 rare earth metals Chemical class 0.000 title claims abstract description 91
- 238000002360 preparation method Methods 0.000 title claims abstract description 64
- 230000003647 oxidation Effects 0.000 claims abstract description 122
- 238000007254 oxidation reaction Methods 0.000 claims abstract description 122
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- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 51
- 239000010439 graphite Substances 0.000 claims abstract description 45
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- 229910018557 Si O Inorganic materials 0.000 claims abstract description 30
- LIVNPJMFVYWSIS-UHFFFAOYSA-N silicon monoxide Inorganic materials [Si-]#[O+] LIVNPJMFVYWSIS-UHFFFAOYSA-N 0.000 claims abstract description 30
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- 238000000034 method Methods 0.000 claims description 40
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Abstract
The invention discloses a rare earth doped binary boride modified gradient oxygen barrier coating and a preparation method thereof, wherein the coating comprises a substrate layer, a transition layer and a self-growing glass layer; the substrate layer comprises a graphite substrate material, the transition layer comprises a rare earth doped binary boride and a silicon carbide material, and the self-grown glass layer comprises a Hf-La-B-Si-O material; the invention overcomes the defects of the prior HfB 2‑ The SiC binary phase ceramic coating has the advantages of high sintering temperature, high material preparation difficulty, energy waste, high-temperature oxidation and loosening, low antioxidation protection temperature and the like, has the advantages of reducing the sintering temperature, simplifying the material preparation difficulty, saving energy consumption, improving the densification of a coating structure, reducing internal defects of the coating, reducing oxidation activity and oxidation consumption, improving service temperature, strengthening oxidation protection effect and prolonging service life, and achieves the effect of stabilizing the antioxidation protection in a high-temperature region of 1700 ℃.
Description
Technical Field
The invention relates to the technical field of high-temperature oxygen-resistant protection of carbon/carbon composite materials, in particular to a rare earth doped binary boride modified oxygen-resistant coating and a preparation method thereof, which can be used for oxidation corrosion protection of carbon/carbon composite materials and parts thereof in a high-temperature environment.
Background
With the rapid development of the aerospace field and the high-tech industry, the demand of high-temperature structural materials is increasing, and graphite materials are regarded as basic materials, and attention is paid to the high chemical stability, the high specific strength, the high specific modulus and the thermal shock resistance of the basic materials. In inert atmosphere, the mechanical properties of graphite materials are in direct proportion with the rise of temperature, and are essential mineral raw materials necessary for traditional industry and strategically emerging industry, and are important resources for the development of high and new technology industry.
When the working environment is an aerobic environment with the temperature higher than 400 ℃, the graphite material can react with oxygen and water in the air to generate CO or CO due to the intense oxidation activity 2 The gas is extremely easy to oxidize and corrode, and the higher the temperature is, the faster the oxidation and corrosion rate is, which seriously affects the use of the gas under high temperature conditions. Therefore, improving the ultra-high temperature oxidation resistance of graphite materials has become a research hotspot in recent years, wherein matrix modification methods and coating techniques are important fields for improving the high temperature performance of graphite materials.
HfB as a critical coating material for high-temperature oxygen barrier protection 2 The SiC binary phase oxygen-blocking coating can stably maintain the oxidation-resistant protection effect in a high-temperature environment and plays a great role in the high-temperature oxygen-blocking field of graphite materials. As Zhang Lulu et al (Zhang Lulu. Layered HfB) 2 Preparation of-SiC-based ceramic Material and study of Performance [ D ]]University of eastern university of lewy, 2019.) discloses a HfB 2 A SiC binary phase oxygen barrier coating and a preparation method thereof,and indicates that the static oxidation protection of the binary phase ceramic material can reach 1300 ℃, and the binary phase ceramic material has good high-temperature oxidation resistance. V. Gurineau et al (Gurineau V, vilmart G, dorval N, et al Comparison of ZrB) 2 -SiC,HfB 2 -SiC and HfB 2 -SiC-Y 2 O 3 oxidation mechanisms in air using LIF of BO 2 (g)[J]Corrosion Science,2020, 163:108278.) discloses a process for preparing HfB using SPS 2 The method of the SiC oxygen barrier coating indicates that the static oxidation protection of the material can be improved to 1600 ℃, but the method requires extremely high sintering temperature (about 1900-2000 ℃), which definitely limits the possibility of preparing the material and greatly causes energy waste. It is known that the improvement of the oxidation resistance per 100 ℃ is a very serious challenge for the oxidation-resistant protective coating of graphite materials. With the development of technological strength and the stricter working condition indexes of the service environment of the anti-oxidation coating, the static oxidation temperature of 1300 ℃ and even 1500 ℃ can not meet the anti-oxidation requirement of the graphite material at the present stage, however, hfB 2 The SiC binary phase coating is susceptible to loosening after oxidation at a temperature above 1700 ℃, deteriorating the oxygen barrier effect and the working life, and there is a need for a coating material and a preparation method that can provide a stable and effective oxidation-resistant protective effect in a higher temperature environment.
Disclosure of Invention
In order to solve the technical problems, the technical scheme provided by the invention is as follows:
a rare earth doped binary boride modified gradient oxygen barrier coating comprises a matrix layer, a transition layer and a self-growing glass layer; wherein the matrix layer comprises a graphite base material, and the transition layer is LaB 6 -HfB 2 -a SiC transition layer comprising rare earth doped binary boride and a silicon carbide material, said self-grown glass layer comprising Hf-La-B-Si-O material; the substrate layer and the self-growing glass layer are respectively arranged at the inner side and the outermost side, and the transition layer is arranged between the substrate layer and the self-growing glass layer.
Wherein, the invention selects rare earth boride LaB which can improve the compactness of the coating and has high oxidation resistance 6 To dope the additive, can make up for HfB 2 -SiC coatingDefects of the layer during high temperature oxidation; at the same time LaB 6 The atomic groups can be adsorbed to reduce stress concentration at the edges of the pores and the microcracks, and the aperture and the porosity of the coating are reduced; in addition, rare earth La 3+ Will diffuse to SiO 2 In the crystal lattice, the stability and viscosity of the glass layer are thereby improved to promote oxidation inhibition and reduce the oxygen diffusion rate.
In particular, the LaB 6 -HfB 2 The rare earth doping content in the SiC transition layer is 2.5-10 mol%, and the balance is hafnium boride and silicon carbide main phase ceramic; the self-growing glass layer is made of Hf-La-B-Si-O material.
In particular, the thickness of the transition layer is 1000-2000 μm, and the thickness of the self-grown glass layer is 5-20 μm.
In addition, the invention also provides a preparation method of the rare earth doped binary boride modified gradient oxygen barrier coating, which comprises the following steps:
s1, mixing raw materials: lanthanum boride, hafnium boride and silicon carbide are taken as raw materials and mixed in a molar ratio to obtain composite precursor powder;
s2, sintering a transition layer: filling a graphite matrix wrapped by composite precursor powder into a graphite mold, and performing spark plasma sintering in a vacuum environment to prepare graphite@LaB 6 -HfB 2 -a SiC transition layer;
s3, in-situ growth of a glass layer: polishing the spark plasma sintering sample, putting the polished spark plasma sintering sample into a muffle furnace, heating the spark plasma sintering sample along with the furnace, and carrying out in-situ growth of the Hf-La-B-Si-O self-grown glass layer;
s4, product treatment: and after the oxidation sintering is finished, naturally cooling along with a furnace, and taking out to obtain the rare earth doped binary boride modified gradient oxygen barrier coating.
In the method, the chemical composition of the transition layer in the prepared rare earth doped binary boride modified gradient oxygen barrier coating is as follows: laB (Lab) 6 -HfB 2 -SiC; the self-growing glass layer comprises the following components: hf-La-B-Si-O.
Particularly, the preparation method of the rare earth doped binary boride modified gradient oxygen barrier coating in the step S1 comprises the following steps of: 2.5:57.5:40 to 10:50:40;
in particular, the preparation method of the rare earth doped binary boride modified gradient oxygen barrier coating in the step S2 is characterized in that the LaB is prepared by spark plasma sintering 6 -HfB 2 The sintering temperature of the SiC transition layer is: 1400-1600 ℃;
in particular, the preparation method of the rare earth doped binary boride modified gradient oxygen barrier coating in the step S3 comprises the following steps: 1000-1300 ℃;
in particular, the preparation method of the rare earth doped binary boride modified gradient oxygen barrier coating in the step S3 comprises the following steps of: 2-8 h.
Compared with the prior art, the invention has the advantages that:
1. the invention utilizes the rare earth doped modified gradient coating, not only plays the advantages of the gradient coating with a matrix layer, a transition layer and a self-growing glass layer structure in the aspects of reducing internal defects, reducing oxidation activity and oxidation consumption, improving oxygen blocking quality and the like, but also can effectively avoid the loose state evolution of the coating structure caused by inherent high activity of transition metal boride, thereby further exacerbating the problem of failure caused by oxidation loss; meanwhile, the characteristics of promoting sintering compactness and complexing film formation by rare earth doping are also exerted, the advantages of improving densification of a coating structure and inhibiting oxygen diffusion are achieved, and a multiple synergistic oxygen blocking effect is achieved.
2. As an effective high-temperature oxygen-resistant protective coating of the carbon/carbon composite material, the rare earth doped binary boride modified gradient oxygen-resistant coating and the preparation method thereof overcome the defect of HfB 2 The problem of oxidation and bulking of the SiC coating at the temperature of more than 1700 ℃ is solved, and the HfB is improved 2 The service temperature of the SiC coating strengthens the oxidation protection effect and prolongs the service life; meanwhile, the method also solves the problems of high sintering temperature and energy waste of the conventional SPS preparation method, and has the advantages of reducing the sintering temperature, simplifying the material preparation difficulty and saving energy.
3. The invention uses rare earth doped binary boride modified gradient oxygen-blocking coating and the preparation technique thereof, stoneThe high-temperature stable oxygen-blocking protection temperature of the ink material can be raised to 1700 ℃, compared with the prior HfB 2 The SiC-based oxygen-resistant coating is improved by about 100-400 ℃ and shows remarkable oxidation resistance gain effect; meanwhile, the preparation temperature of the coating can be reduced to 1400 ℃ at most, which is about 500 ℃ lower than the sintering temperature of the conventional SPS preparation method, so that the energy is greatly saved, and the preparation difficulty of the product is reduced.
In summary, the present invention overcomes the existing HfB 2 The SiC binary phase ceramic coating has the advantages of high sintering temperature, high material preparation difficulty, energy waste, high-temperature oxidation and loosening, low antioxidation protection temperature and the like, has the advantages of reducing the sintering temperature, simplifying the material preparation difficulty, saving energy consumption, improving the densification of the coating structure, reducing the internal defects of the coating, reducing the oxidation activity and the oxidation consumption, improving the service temperature, strengthening the oxidation protection effect and prolonging the service life, and achieves the effect of stabilizing the antioxidation protection in a high-temperature region of 1700 ℃.
Drawings
Fig. 1 is a schematic structural view of the present invention.
Fig. 2 is a process flow diagram of the present invention.
FIG. 3 shows the results of X-ray diffraction phase analysis of the gradient oxygen barrier coatings obtained in examples 1 to 8 of the present invention.
FIG. 4 is a scanning electron microscope surface morphology of the gradient oxygen barrier coating obtained in example 1 of the present invention.
FIG. 5 is a scanning electron microscope surface morphology of the gradient oxygen barrier coating obtained in example 2 of the present invention.
FIG. 6 is a scanning electron microscope surface morphology of the gradient oxygen barrier coating obtained in example 3 of the present invention.
FIG. 7 is a scanning electron microscope surface morphology of the gradient oxygen barrier coating obtained in example 4 of the present invention.
FIG. 8 is a scanning electron microscope surface morphology of the gradient oxygen barrier coating obtained in example 5 of the present invention.
FIG. 9 is a scanning electron microscope surface morphology of the gradient oxygen barrier coating obtained in example 6 of the present invention.
FIG. 10 is a scanning electron microscope surface morphology of the gradient oxygen barrier coating obtained in example 7 of the present invention.
FIG. 11 is a scanning electron microscope surface morphology of the gradient oxygen barrier coating obtained in example 8 of the present invention.
FIG. 12 is a cross-sectional view of a scanning electron microscope of the gradient oxygen barrier coating obtained in example 1 of the present invention.
FIG. 13 is a cross-sectional view of a scanning electron microscope of the gradient oxygen barrier coating obtained in example 2 of the present invention.
FIG. 14 is a cross-sectional view of a scanning electron microscope of the gradient oxygen barrier coating obtained in example 3 of the present invention.
FIG. 15 is a cross-sectional view of a scanning electron microscope of the gradient oxygen barrier coating obtained in example 4 of the present invention.
FIG. 16 is a cross-sectional view of a scanning electron microscope of the gradient oxygen barrier coating obtained in example 5 of the present invention.
FIG. 17 is a cross-sectional view of a scanning electron microscope of the gradient oxygen barrier coating obtained in example 6 of the present invention.
FIG. 18 is a cross-sectional view of a scanning electron microscope of the gradient oxygen barrier coating obtained in example 7 of the present invention.
FIG. 19 is a cross-sectional view of a scanning electron microscope of the gradient oxygen barrier coating obtained in example 8 of the present invention.
FIG. 20 is an oxidized weight gain curve of the gradient oxygen barrier coatings obtained in examples 1 to 8 of the present invention.
FIG. 21 is a graph showing the oxidation rate of the gradient oxygen barrier coatings obtained in examples 1 to 8 of the present invention.
FIG. 22 is an oxidation-protecting efficiency curve of the gradient oxygen-barrier coatings obtained in examples 1 to 8 of the present invention.
FIG. 23 shows the results of X-ray diffraction phase analysis obtained in comparative examples 1 to 2 of the present invention.
FIG. 24 is a surface topography of a scanning electron microscope obtained in comparative example 1 of the present invention.
FIG. 25 is a surface topography of a scanning electron microscope obtained in comparative example 2 of the present invention.
FIG. 26 is a cross-sectional view of a scanning electron microscope obtained in comparative example 1 of the present invention.
FIG. 27 is a cross-sectional view of a scanning electron microscope obtained in comparative example 2 of the present invention.
FIG. 28 shows the results of X-ray diffraction phase analysis obtained in comparative examples 3 to 4 of the present invention.
FIG. 29 is a surface topography of a scanning electron microscope obtained in comparative example 3 of the present invention.
FIG. 30 is a surface topography of a scanning electron microscope obtained in comparative example 4 of the present invention.
FIG. 31 is a cross-sectional view of a scanning electron microscope obtained in comparative example 3 of the present invention.
FIG. 32 is a cross-sectional view of a scanning electron microscope obtained in comparative example 4 of the present invention.
Fig. 33 is a graph of weight gain data obtained in comparative examples 1 to 4 of the present invention.
FIG. 34 is a graph showing the oxidation rates obtained in comparative examples 1 to 4 of the present invention.
FIG. 35 is a graph showing the oxidation preventive efficiency obtained in comparative examples 1 to 4 of the present invention.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments of the present invention. The components of the embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.
Example 1
In the embodiment, graphite is used as a substrate, and a gradient oxygen-blocking coating is formed by a substrate layer, a transition layer and a self-grown glass layer. LaB (Lab) 6 -HfB 2 The rare earth doping content in the SiC transition layer is 5mol%, the balance is hafnium boride and silicon carbide main phase ceramic, and the thickness of the transition layer is 1500 mu m; the self-grown glass layer is made of Hf-La-B-Si-O material and has a thickness of 10 μm. The method comprises the following specific steps:
the preparation method of the rare earth doped binary boride modified gradient oxygen barrier coating comprises the following steps:
s1, mixing raw materials: lanthanum boride, hafnium boride and silicon carbide are used as raw materials, and the molar ratio is 5:55:40, mixing to obtain composite precursor powder;
s2, sintering a transition layer: coating the graphite matrix with the composite precursor powderFilling the powder into a graphite mold, and performing spark plasma sintering in a vacuum environment, wherein the sintering temperature is as follows: preparation of graphite @ LaB at 1500 ℃ 6 -HfB 2 -a SiC transition layer;
s3, in-situ growth of a glass layer: grinding the spark plasma sintering sample, putting the ground spark plasma sintering sample into a muffle furnace, heating the ground spark plasma sintering sample along with the furnace, and performing in-situ growth of the Hf-La-B-Si-O self-grown glass layer, wherein the growth temperature is as follows: 1000 ℃, the growth time is as follows: 2h;
s4, product treatment: and after the oxidation sintering is finished, naturally cooling along with a furnace, and taking out to obtain the rare earth doped binary boride modified gradient oxygen barrier coating.
The embodiment provides a rare earth doped binary boride modified gradient oxygen barrier coating preferable proportion and a preparation process thereof, wherein a phase structure, a surface morphology, a section morphology, an oxidation weight gain curve, an oxidation rate and an oxidation protection efficiency curve are respectively shown in fig. 3, fig. 4, fig. 12 and fig. 20-22, and oxidation weight gain and oxidation protection efficiency results at 1700 ℃ are shown in table 1. From the graph and the table, the rare earth doped binary boride modified gradient oxygen barrier coating provided by the embodiment has the advantages of good phase structure, excellent surface morphology, compact section morphology, no internal defects such as holes and the like, obvious oxidation resistance effect and capability of stably providing oxygen barrier protection effect in a high temperature region of 1700 ℃. In addition, compared with the conventional SPS preparation method, the sintering temperature is greatly reduced, the effects of saving energy and simplifying the process are achieved to a certain extent, and the method has the advantages of improving the service temperature and strengthening the oxidation protection effect.
Example 2
In the embodiment, graphite is used as a substrate, and a gradient oxygen-blocking coating is formed by a substrate layer, a transition layer and a self-grown glass layer. LaB (Lab) 6 -HfB 2 The rare earth doping content in the SiC transition layer is 5mol%, the balance is hafnium boride and silicon carbide main phase ceramic, and the thickness of the transition layer is 1500 mu m; the self-grown glass layer is made of Hf-La-B-Si-O material and has a thickness of 10 μm. The method comprises the following specific steps:
the preparation method of the rare earth doped binary boride modified gradient oxygen barrier coating comprises the following steps:
s1, mixing raw materials: lanthanum boride, hafnium boride and silicon carbide are used as raw materials, and the molar ratio is 5:55:40, mixing to obtain composite precursor powder;
s2, sintering a transition layer: filling the graphite matrix wrapped by the composite precursor powder into a graphite mold, and performing spark plasma sintering in a vacuum environment, wherein the sintering temperature is as follows: preparation of graphite @ LaB at 1500 ℃ 6 -HfB 2 -a SiC transition layer;
s3, in-situ growth of a glass layer: grinding the spark plasma sintering sample, putting the ground spark plasma sintering sample into a muffle furnace, heating the ground spark plasma sintering sample along with the furnace, and performing in-situ growth of the Hf-La-B-Si-O self-grown glass layer, wherein the growth temperature is as follows: 1100 ℃, the growth time is as follows: 2h;
s4, product treatment: and after the oxidation sintering is finished, naturally cooling along with a furnace, and taking out to obtain the rare earth doped binary boride modified gradient oxygen barrier coating.
The embodiment provides a rare earth doped binary boride modified gradient oxygen barrier coating preferable proportion and a preparation process thereof, wherein a phase structure, a surface morphology, a section morphology, an oxidation weight gain curve, an oxidation rate and an oxidation protection efficiency curve are respectively shown in fig. 3, fig. 5, fig. 13 and fig. 20-22, and oxidation weight gain and oxidation protection efficiency results at 1700 ℃ are shown in table 1. From the graph and the table, the rare earth doped binary boride modified gradient oxygen barrier coating provided by the embodiment has the advantages of good phase structure, excellent surface morphology, compact section morphology, no internal defects such as holes and the like, obvious oxidation resistance effect and capability of stably providing oxygen barrier protection effect in a high temperature region of 1700 ℃. In addition, compared with the conventional SPS preparation method, the sintering temperature is greatly reduced, the effects of saving energy and simplifying the process are achieved to a certain extent, and the method has the advantages of improving the service temperature and strengthening the oxidation protection effect.
Example 3
In the embodiment, graphite is used as a substrate, and a gradient oxygen-blocking coating is formed by a substrate layer, a transition layer and a self-grown glass layer. LaB (Lab) 6 -HfB 2 The rare earth doping content in the SiC transition layer is 5mol%, the balance is hafnium boride and silicon carbide main phase ceramic, and the thickness of the transition layer is 1500 mu m; the self-grown glass layer is made of Hf-La-B-Si-O material and has a thickness of 10 μm. The method comprises the following specific steps:
the preparation method of the rare earth doped binary boride modified gradient oxygen barrier coating comprises the following steps:
s1, mixing raw materials: lanthanum boride, hafnium boride and silicon carbide are used as raw materials, and the molar ratio is 5:55:40, mixing to obtain composite precursor powder;
s2, sintering a transition layer: filling the graphite matrix wrapped by the composite precursor powder into a graphite mold, and performing spark plasma sintering in a vacuum environment, wherein the sintering temperature is as follows: preparation of graphite @ LaB at 1500 ℃ 6 -HfB 2 -a SiC transition layer;
s3, in-situ growth of a glass layer: grinding the spark plasma sintering sample, putting the ground spark plasma sintering sample into a muffle furnace, heating the ground spark plasma sintering sample along with the furnace, and performing in-situ growth of the Hf-La-B-Si-O self-grown glass layer, wherein the growth temperature is as follows: 1200 ℃, growth time: 2h;
s4, product treatment: and after the oxidation sintering is finished, naturally cooling along with a furnace, and taking out to obtain the rare earth doped binary boride modified gradient oxygen barrier coating.
The embodiment provides a rare earth doped binary boride modified gradient oxygen barrier coating preferable proportion and a preparation process thereof, wherein a phase structure, a surface morphology, a section morphology, an oxidation weight gain curve, an oxidation rate and an oxidation protection efficiency curve are respectively shown in fig. 3, fig. 6, fig. 14 and fig. 20-22, and oxidation weight gain and oxidation protection efficiency results at 1700 ℃ are shown in table 1. From the graph and the table, the rare earth doped binary boride modified gradient oxygen barrier coating provided by the embodiment has the advantages of good phase structure, excellent surface morphology, compact section morphology, no internal defects such as holes and the like, obvious oxidation resistance effect and capability of stably providing oxygen barrier protection effect in a high temperature region of 1700 ℃. In addition, compared with the conventional SPS preparation method, the sintering temperature is greatly reduced, the effects of saving energy and simplifying the process are achieved to a certain extent, and the method has the advantages of improving the service temperature and strengthening the oxidation protection effect.
Example 4
In the embodiment, graphite is used as a substrate, and a gradient oxygen-blocking coating is formed by a substrate layer, a transition layer and a self-grown glass layer. LaB (Lab) 6 -HfB 2 The rare earth doping content in the SiC transition layer is 5mol%The balance of hafnium boride and silicon carbide main phase ceramic, and the thickness of the transition layer is 1500 mu m; the self-grown glass layer is made of Hf-La-B-Si-O material and has a thickness of 10 μm. The method comprises the following specific steps:
the preparation method of the rare earth doped binary boride modified gradient oxygen barrier coating comprises the following steps:
s1, mixing raw materials: lanthanum boride, hafnium boride and silicon carbide are used as raw materials, and the molar ratio is 5:55:40, mixing to obtain composite precursor powder;
s2, sintering a transition layer: filling the graphite matrix wrapped by the composite precursor powder into a graphite mold, and performing spark plasma sintering in a vacuum environment, wherein the sintering temperature is as follows: preparation of graphite @ LaB at 1500 ℃ 6 -HfB 2 -a SiC transition layer;
s3, in-situ growth of a glass layer: grinding the spark plasma sintering sample, putting the ground spark plasma sintering sample into a muffle furnace, heating the ground spark plasma sintering sample along with the furnace, and performing in-situ growth of the Hf-La-B-Si-O self-grown glass layer, wherein the growth temperature is as follows: 1300 ℃, growth time: 2h;
s4, product treatment: and after the oxidation sintering is finished, naturally cooling along with a furnace, and taking out to obtain the rare earth doped binary boride modified gradient oxygen barrier coating.
The embodiment provides a rare earth doped binary boride modified gradient oxygen barrier coating preferable proportion and a preparation process thereof, wherein a phase structure, a surface morphology, a section morphology, an oxidation weight gain curve, an oxidation rate and an oxidation protection efficiency curve are respectively shown in fig. 3, fig. 7, fig. 15 and fig. 20-22, and oxidation weight gain and oxidation protection efficiency results at 1700 ℃ are shown in table 1. From the graph and the table, the rare earth doped binary boride modified gradient oxygen barrier coating provided by the embodiment has the advantages of good phase structure, excellent surface morphology, compact section morphology, no internal defects such as holes and the like, obvious oxidation resistance effect and capability of stably providing oxygen barrier protection effect in a high temperature region of 1700 ℃. In addition, compared with the conventional SPS preparation method, the sintering temperature is greatly reduced, the effects of saving energy and simplifying the process are achieved to a certain extent, and the method has the advantages of improving the service temperature and strengthening the oxidation protection effect.
Example 5
In the embodiment, graphite is used as a substrate, and a gradient oxygen-blocking coating is formed by a substrate layer, a transition layer and a self-grown glass layer. LaB (Lab) 6 -HfB 2 The rare earth doping content in the SiC transition layer is 5mol%, the balance is hafnium boride and silicon carbide main phase ceramic, and the thickness of the transition layer is 1500 mu m; the self-grown glass layer is made of Hf-La-B-Si-O material and has a thickness of 10 μm. The method comprises the following specific steps:
the preparation method of the rare earth doped binary boride modified gradient oxygen barrier coating comprises the following steps:
s1, mixing raw materials: lanthanum boride, hafnium boride and silicon carbide are used as raw materials, and the molar ratio is 5:55:40, mixing to obtain composite precursor powder;
s2, sintering a transition layer: filling the graphite matrix wrapped by the composite precursor powder into a graphite mold, and performing spark plasma sintering in a vacuum environment, wherein the sintering temperature is as follows: preparation of graphite @ LaB at 1500 ℃ 6 -HfB 2 -a SiC transition layer;
s3, in-situ growth of a glass layer: grinding the spark plasma sintering sample, putting the ground spark plasma sintering sample into a muffle furnace, heating the ground spark plasma sintering sample along with the furnace, and performing in-situ growth of the Hf-La-B-Si-O self-grown glass layer, wherein the growth temperature is as follows: 1100 ℃, the growth time is as follows: 6h;
s4, product treatment: and after the oxidation sintering is finished, naturally cooling along with a furnace, and taking out to obtain the rare earth doped binary boride modified gradient oxygen barrier coating.
The embodiment provides a rare earth doped binary boride modified gradient oxygen barrier coating and a preferred proportion and a preferred preparation process thereof, wherein a phase structure, a surface morphology, a section morphology, an oxidation weight gain curve, an oxidation rate and an oxidation protection efficiency curve are respectively shown in fig. 3, fig. 8, fig. 16 and fig. 20-22, and oxidation weight gain and oxidation protection efficiency results at 1700 ℃ are shown in table 1. From the graph and the table, the rare earth doped binary boride modified gradient oxygen barrier coating provided by the embodiment has the advantages of good phase structure, excellent surface morphology, compact section morphology, no internal defects such as holes and the like, obvious oxidation resistance effect and capability of stably providing oxygen barrier protection effect in a high temperature region of 1700 ℃. In addition, compared with the conventional SPS preparation method, the sintering temperature is greatly reduced, the effects of saving energy and simplifying the process are achieved to a certain extent, and the method has the advantages of improving the service temperature and strengthening the oxidation protection effect.
Example 6
In the embodiment, graphite is used as a substrate, and a gradient oxygen-blocking coating is formed by a substrate layer, a transition layer and a self-grown glass layer. LaB (Lab) 6 -HfB 2 The rare earth doping content in the SiC transition layer is 5mol%, the balance is hafnium boride and silicon carbide main phase ceramic, and the thickness of the transition layer is 1500 mu m; the self-grown glass layer is made of Hf-La-B-Si-O material and has a thickness of 10 μm. The method comprises the following specific steps:
the preparation method of the rare earth doped binary boride modified gradient oxygen barrier coating comprises the following steps:
s1, mixing raw materials: lanthanum boride, hafnium boride and silicon carbide are used as raw materials, and the molar ratio is 5:55:40, mixing to obtain composite precursor powder;
s2, sintering a transition layer: filling the graphite matrix wrapped by the composite precursor powder into a graphite mold, and performing spark plasma sintering in a vacuum environment, wherein the sintering temperature is as follows: preparation of graphite @ LaB at 1500 ℃ 6 -HfB 2 -a SiC transition layer;
s3, in-situ growth of a glass layer: grinding the spark plasma sintering sample, putting the ground spark plasma sintering sample into a muffle furnace, heating the ground spark plasma sintering sample along with the furnace, and performing in-situ growth of the Hf-La-B-Si-O self-grown glass layer, wherein the growth temperature is as follows: 1100 ℃, the growth time is as follows: 8h;
s4, product treatment: and after the oxidation sintering is finished, naturally cooling along with a furnace, and taking out to obtain the rare earth doped binary boride modified gradient oxygen barrier coating.
The embodiment provides a rare earth doped binary boride modified gradient oxygen barrier coating preferable proportion and a preparation process thereof, wherein a phase structure, a surface morphology, a section morphology, an oxidation weight gain curve, an oxidation rate and an oxidation protection efficiency curve are respectively shown in fig. 3, fig. 9, fig. 17 and fig. 20-22, and oxidation weight gain and oxidation protection efficiency results at 1700 ℃ are shown in table 1. From the graph and the table, the rare earth doped binary boride modified gradient oxygen barrier coating provided by the embodiment has the advantages of good phase structure, excellent surface morphology, compact section morphology, no internal defects such as holes and the like, obvious oxidation resistance effect and capability of stably providing oxygen barrier protection effect in a high temperature region of 1700 ℃. In addition, compared with the conventional SPS preparation method, the sintering temperature is greatly reduced, the effects of saving energy and simplifying the process are achieved to a certain extent, and the method has the advantages of improving the service temperature and strengthening the oxidation protection effect.
Example 7
In the embodiment, graphite is used as a substrate, and a gradient oxygen-blocking coating is formed by a substrate layer, a transition layer and a self-grown glass layer. LaB (Lab) 6 -HfB 2 The rare earth doping content in the SiC transition layer is 2.5mol%, the balance is hafnium boride and silicon carbide main phase ceramic, and the thickness of the transition layer is 1000 mu m; the self-grown glass layer is made of Hf-La-B-Si-O material and has a thickness of 5 μm. The method comprises the following specific steps:
the preparation method of the rare earth doped binary boride modified gradient oxygen barrier coating comprises the following steps:
s1, mixing raw materials: lanthanum boride, hafnium boride and silicon carbide are used as raw materials, and the molar ratio is 2.5:57.5:40, mixing to obtain composite precursor powder;
s2, sintering a transition layer: filling the graphite matrix wrapped by the composite precursor powder into a graphite mold, and performing spark plasma sintering in a vacuum environment, wherein the sintering temperature is as follows: preparation of graphite @ LaB at 1400 ℃ 6 -HfB 2 -a SiC transition layer;
s3, in-situ growth of a glass layer: grinding the spark plasma sintering sample, putting the ground spark plasma sintering sample into a muffle furnace, heating the ground spark plasma sintering sample along with the furnace, and performing in-situ growth of the Hf-La-B-Si-O self-grown glass layer, wherein the growth temperature is as follows: 1000 ℃, the growth time is as follows: 2h;
s4, product treatment: and after the oxidation sintering is finished, naturally cooling along with a furnace, and taking out to obtain the rare earth doped binary boride modified gradient oxygen barrier coating.
The embodiment provides a rare earth doped binary boride modified gradient oxygen barrier coating ratio and a preparation process thereof, wherein a phase structure, a surface morphology, a section morphology, an oxidation weight gain curve, an oxidation rate and an oxidation protection efficiency curve are respectively shown in fig. 3, 10, 18 and 20-22, and oxidation weight gain and oxidation protection efficiency results at 1700 ℃ are shown in table 1. From the graph and the table, the rare earth doped binary boride modified gradient oxygen barrier coating provided by the embodiment has the advantages of good phase structure, excellent surface morphology, compact section morphology, no internal defects such as holes and the like, obvious oxidation resistance effect and capability of stably providing oxygen barrier protection effect in a high temperature region of 1700 ℃. In addition, compared with the conventional SPS preparation method, the sintering temperature is greatly reduced, the effects of saving energy and simplifying the process are achieved to a certain extent, and the method has the advantages of improving the service temperature and strengthening the oxidation protection effect.
Example 8
In the embodiment, graphite is used as a substrate, and a gradient oxygen-blocking coating is formed by a substrate layer, a transition layer and a self-grown glass layer. LaB (Lab) 6 -HfB 2 The rare earth doping content in the SiC transition layer is 10mol%, the balance is hafnium boride and silicon carbide main phase ceramic, and the thickness of the transition layer is 2000 mu m; the self-grown glass layer is made of Hf-La-B-Si-O material and has a thickness of 20 μm. The method comprises the following specific steps:
the preparation method of the rare earth doped binary boride modified gradient oxygen barrier coating comprises the following steps:
s1, mixing raw materials: lanthanum boride, hafnium boride and silicon carbide are used as raw materials, and the molar ratio is 10:50:40, mixing to obtain composite precursor powder;
s2, sintering a transition layer: filling the graphite matrix wrapped by the composite precursor powder into a graphite mold, and performing spark plasma sintering in a vacuum environment, wherein the sintering temperature is as follows: preparation of graphite @ LaB at 1600 ℃ 6 -HfB 2 -a SiC transition layer;
s3, in-situ growth of a glass layer: grinding the spark plasma sintering sample, putting the ground spark plasma sintering sample into a muffle furnace, heating the ground spark plasma sintering sample along with the furnace, and performing in-situ growth of the Hf-La-B-Si-O self-grown glass layer, wherein the growth temperature is as follows: 1300 ℃, growth time: 8h;
s4, product treatment: and after the oxidation sintering is finished, naturally cooling along with a furnace, and taking out to obtain the rare earth doped binary boride modified gradient oxygen barrier coating.
The embodiment provides a rare earth doped binary boride modified gradient oxygen barrier coating ratio and a preparation process thereof, wherein a phase structure, a surface morphology, a section morphology, an oxidation weight gain curve, an oxidation rate and an oxidation protection efficiency curve are respectively shown in fig. 3, 11 and 19-22, and oxidation weight gain and oxidation protection efficiency results at 1700 ℃ are shown in table 1. From the graph and the table, the rare earth doped binary boride modified gradient oxygen barrier coating provided by the embodiment has the advantages of good phase structure, excellent surface morphology, compact section morphology, no internal defects such as holes and the like, obvious oxidation resistance effect and capability of stably providing oxygen barrier protection effect in a high temperature region of 1700 ℃. In addition, compared with the conventional SPS preparation method, the sintering temperature is greatly reduced, the effects of saving energy and simplifying the process are achieved to a certain extent, and the method has the advantages of improving the service temperature and strengthening the oxidation protection effect.
Comparative example 1
The comparative example uses graphite as a substrate, a gradient oxygen-blocking coating is formed by a substrate layer, a transition layer and a self-grown glass layer, and the transition layer HfB 2 The SiC is free of rare earth doping, is made of hafnium boride and silicon carbide main phase ceramic, and the thickness of the transition layer is 1500 mu m; similarly, the self-grown glass layer is made of Hf-B-Si-O material, has no rare earth doping, and has the thickness of 10 mu m. The method comprises the following specific steps:
the preparation method of the rare earth doped binary boride modified gradient oxygen barrier coating comprises the following steps:
s1, mixing raw materials: hafnium boride and silicon carbide are used as raw materials, and the molar ratio is 60:40, mixing to obtain composite precursor powder;
s2, sintering a transition layer: filling the graphite matrix wrapped by the composite precursor powder into a graphite mold, and performing spark plasma sintering in a vacuum environment, wherein the sintering temperature is as follows: preparation of graphite @ HfB at 1500 ℃ 2 -a SiC transition layer;
s3, in-situ growth of a glass layer: grinding the spark plasma sintering sample, putting the ground spark plasma sintering sample into a muffle furnace, heating the ground spark plasma sintering sample along with the furnace, and performing in-situ growth of the Hf-B-Si-O self-grown glass layer, wherein the growth temperature is as follows: 1100 ℃, the growth time is as follows: 2h;
s4, product treatment: and after the oxidation sintering is finished, naturally cooling along with a furnace, and taking out to obtain the rare earth doped binary boride modified gradient oxygen barrier coating.
The comparative example provides a comparative case without rare earth doped binary boride modification, wherein the phase structure, the surface morphology, the section morphology, the oxidation weight gain curve, the oxidation rate and the oxidation protection efficiency curve are shown in fig. 23, 25, 29 and 33-35, and the oxidation weight gain and oxidation protection efficiency results at 1700 ℃ are shown in table 1. As can be seen from the graph and the table, although the gradient oxygen-resistant coating provided by the comparative example keeps good in phase structure, compared with the example 2, the oxygen-resistant protection effect in the 1700 ℃ high temperature region is obviously inferior, which indicates the advantage and necessity of improving the oxidation-resistant protection effect of the gradient oxygen-resistant coating by utilizing rare earth doped binary boride modification.
Comparative example 2
The comparative example uses graphite as a substrate, a gradient oxygen-blocking coating is formed by a substrate layer, a transition layer and a self-grown glass layer, and the transition layer HfB 2 The SiC is free of rare earth doping, is made of hafnium boride and silicon carbide main phase ceramic, and the thickness of the transition layer is 1500 mu m; similarly, the self-grown glass layer is made of Hf-B-Si-O material, has no rare earth doping, and has the thickness of 10 mu m. The method comprises the following specific steps:
the preparation method of the rare earth doped binary boride modified gradient oxygen barrier coating comprises the following steps:
s1, mixing raw materials: hafnium boride and silicon carbide are used as raw materials, and the molar ratio is 60:40, mixing to obtain composite precursor powder;
s2, sintering a transition layer: filling the graphite matrix wrapped by the composite precursor powder into a graphite mold, and performing spark plasma sintering in a vacuum environment, wherein the sintering temperature is as follows: preparation of graphite @ HfB at 1500 ℃ 2 -a SiC transition layer;
s3, in-situ growth of a glass layer: grinding the spark plasma sintering sample, putting the ground spark plasma sintering sample into a muffle furnace, heating the ground spark plasma sintering sample along with the furnace, and performing in-situ growth of the Hf-B-Si-O self-grown glass layer, wherein the growth temperature is as follows: 1200 ℃, growth time: 2h;
s4, product treatment: and after the oxidation sintering is finished, naturally cooling along with a furnace, and taking out to obtain the rare earth doped binary boride modified gradient oxygen barrier coating.
The comparative example provides a comparative case without rare earth doped binary boride modification, wherein the phase structure, the surface morphology, the section morphology, the oxidation weight gain curve, the oxidation rate and the oxidation protection efficiency curve are shown in fig. 23, fig. 26, fig. 30 and fig. 33 to fig. 35, and the oxidation weight gain and oxidation protection efficiency results at 1700 ℃ are shown in table 1. As can be seen from the graph and the table, although the gradient oxygen-resistant coating provided by the comparative example keeps good in phase structure, compared with the example 3, the oxygen-resistant protection effect in the 1700 ℃ high temperature region is obviously inferior, which indicates the advantage and necessity of improving the oxidation-resistant protection effect of the gradient oxygen-resistant coating by utilizing rare earth doped binary boride modification.
Comparative example 3
The comparative example uses graphite as a substrate, and an oxygen barrier coating is formed by a substrate layer and a transition layer, and has no self-growing glass layer. LaB (Lab) 6 -HfB 2 The rare earth doping content in the SiC transition layer is 2.5mol%, the balance is hafnium boride and silicon carbide main phase ceramic, and the thickness of the transition layer is 1000 mu m. The method comprises the following specific steps:
the preparation method of the rare earth doped binary boride modified oxygen barrier coating comprises the following steps:
s1, mixing raw materials: lanthanum boride, hafnium boride and silicon carbide are used as raw materials, and the molar ratio is 2.5:57.5:40, mixing to obtain composite precursor powder;
s2, sintering a transition layer: filling the graphite matrix wrapped by the composite precursor powder into a graphite mold, and performing spark plasma sintering in a vacuum environment, wherein the sintering temperature is as follows: preparation of graphite @ LaB at 1400 ℃ 6 -HfB 2 -a SiC transition layer;
s3, product treatment: and after sintering, naturally cooling along with the furnace, and taking out to obtain the rare earth doped binary boride modified oxygen barrier coating.
The comparative example provides a comparative case without gradient coating structural design, namely, self-repairing glass layer is not generated in situ, wherein the phase structure, the surface morphology, the section morphology, the oxidation weight gain curve, the oxidation rate and the oxidation protection efficiency curve are respectively shown in fig. 24, fig. 27, fig. 31 and fig. 33-35, and the oxidation weight gain and oxidation protection efficiency results at 1700 ℃ are shown in table 1. As can be seen from the figures and tables, although the comparative example maintains good phase structure, compared with example 7, the oxygen-blocking protection effect in the high temperature region of 1700 ℃ is obviously inferior, which indicates the advantages and the necessity of using the gradient coating design with the substrate layer, the transition layer and the self-growth glass layer structure in the invention in improving the oxidation-blocking protection effect of the gradient oxygen-blocking coating.
Comparative example 4
The comparative example uses graphite as a substrate, and an oxygen barrier coating is formed by a substrate layer and a transition layer, and has no self-growing glass layer. LaB (Lab) 6 -HfB 2 The rare earth doping content in the SiC transition layer is 10mol%, the balance is hafnium boride and silicon carbide main phase ceramic, and the thickness of the transition layer is 2000 mu m. The method comprises the following specific steps:
the preparation method of the rare earth doped binary boride modified oxygen barrier coating comprises the following steps:
s1, mixing raw materials: lanthanum boride, hafnium boride and silicon carbide are used as raw materials, and the molar ratio is 10:50:40, mixing to obtain composite precursor powder;
s2, sintering a transition layer: filling the graphite matrix wrapped by the composite precursor powder into a graphite mold, and performing spark plasma sintering in a vacuum environment, wherein the sintering temperature is as follows: preparation of graphite @ LaB at 1600 ℃ 6 -HfB 2 -a SiC transition layer;
s3, product treatment: and after sintering, naturally cooling along with the furnace, and taking out to obtain the rare earth doped binary boride modified oxygen barrier coating.
The comparative example provides a comparative case without gradient coating structural design, namely, self-repairing glass layer is not generated in situ, wherein the phase structure, the surface morphology, the section morphology, the oxidation weight gain curve, the oxidation rate and the oxidation protection efficiency curve are respectively shown in fig. 24, fig. 28 and fig. 32-35, and the oxidation weight gain and oxidation protection efficiency results at 1700 ℃ are shown in table 1. As can be seen from the figures and tables, although the comparative example maintains good phase structure, compared with example 8, the oxygen-blocking protection effect in the high temperature region of 1700 ℃ is obviously inferior, which indicates the advantages and the necessity of using the gradient coating design with the structures of the substrate layer, the transition layer and the self-growth glass layer in the invention in improving the oxidation-blocking protection effect of the gradient oxygen-blocking coating.
Table 1 results of oxidation weight gain and oxidation protection efficiency at 1700℃
| Weight gain by oxidation/(10) -2 )g·cm -2 | Protective efficiency/% | |
| Example 1 | 1.135 | 99.519 |
| Example 2 | 1.010 | 99.832 |
| Example 3 | 1.076 | 99.670 |
| Example 4 | 1.252 | 99.468 |
| Example 5 | 0.976 | 99.864 |
| Example 6 | 1.134 | 99.735 |
| Example 7 | 1.199 | 99.409 |
| Example 8 | 1.589 | 98.841 |
| Comparative example 1 | 1.399 | 99.055 |
| Comparative example 2 | 1.366 | 99.249 |
| Comparative example 3 | 1.579 | 97.682 |
| Comparative example 4 | 7.920 | 90.957 |
The invention and its embodiments have been described above with no limitation, and the actual construction is not limited to the embodiments of the invention as shown in the drawings. In summary, if one of ordinary skill in the art is informed by this disclosure, a structural manner and an embodiment similar to the technical solution should not be creatively devised without departing from the gist of the present invention.
Claims (8)
1. The rare earth doped binary boride modified gradient oxygen barrier coating is characterized by comprising a substrate layer, a transition layer and a self-growing glass layer; wherein the matrix layer comprises graphite base material, and the transition layer is LaB 6 -HfB 2 -a SiC transition layer comprising rare earth doped binary boride and a silicon carbide material, said self-grown glass layer comprising Hf-La-B-Si-O material; the substrate layer and the self-growing glass layer are respectively arranged at the inner side and the outermost side, and the transition layer is arranged between the substrate layer and the self-growing glass layer.
2. The rare earth doped binary boride modified gradient oxygen barrier coating according to claim 1, wherein the rare earth doping content in the transition layer is 2.5-10 mol%, and the balance is hafnium boride and silicon carbide main phase ceramic.
3. The rare earth doped binary boride modified gradient oxygen barrier coating according to claim 1, wherein the thickness of the transition layer is 1000-2000 μm, and the thickness of the self-grown glass layer is 5-20 μm.
4. The preparation method of the rare earth doped binary boride modified gradient oxygen barrier coating is characterized by comprising the following steps of:
s1, mixing raw materials: lanthanum boride, hafnium boride and silicon carbide are taken as raw materials and mixed in a molar ratio to obtain composite precursor powder;
s2, sintering a transition layer: filling a graphite matrix wrapped by composite precursor powder into a graphite mold, and performing spark plasma sintering in a vacuum environment to prepare graphite@LaB 6 -HfB 2 -a SiC transition layer;
s3, in-situ growth of a glass layer: polishing the spark plasma sintering sample, putting the polished spark plasma sintering sample into a muffle furnace, heating the spark plasma sintering sample along with the furnace, and carrying out in-situ growth of the Hf-La-B-Si-O self-grown glass layer;
s4, product treatment: naturally cooling along with the furnace after the oxidation sintering is finished, and taking out to obtain the rare earth doped binary boride modified gradient oxygen barrier coating;
in the method, the chemical composition of the transition layer in the prepared rare earth doped binary boride modified gradient oxygen barrier coating is as follows: laB (Lab) 6 -HfB 2 -SiC; the self-growing glass layer comprises the following components: hf-La-B-Si-O.
5. The method for preparing the rare earth doped binary boride modified gradient oxygen barrier coating according to claim 1, wherein in the step S1, the molar ratio range of the raw materials of lanthanum boride, hafnium boride and silicon carbide is as follows: 2.5:57.5:40 to 10:50:40.
6. The method for preparing the rare earth doped binary boride modified gradient oxygen barrier coating according to claim 1, wherein in the step S2, laB is prepared by spark plasma sintering 6 -HfB 2 The sintering temperature of the SiC transition layer is: 1400-1600 ℃.
7. The method for preparing the rare earth doped binary boride modified gradient oxygen barrier coating according to claim 1, wherein in the step S3, the growth temperature of the Hf-La-B-Si-O self-growth glass layer is as follows: 1000-1300 ℃; .
8. The method for preparing the rare earth doped binary boride modified gradient oxygen barrier coating according to claim 1, wherein in the step S3, the growth time of the Hf-La-B-Si-O self-growth glass layer is as follows: 2-8 h.
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