CN110818426A - HfB on surface of carbon material2-TaSi2Preparation method of-SiC oxidation resistant coating - Google Patents

Abstract

The invention discloses HfB on the surface of a carbon material₂‑TaSi₂The preparation method of the-SiC oxidation resistant coating comprises the steps of weighing HfB with a certain proportion₂、TaSi₂Fully mixing SiC powder, wrapping carbon material in a graphite mould by using the mixed powder, pressing by using a graphite pressure head, putting the mould into a discharge plasma sintering furnace (SPS) for sintering treatment, wherein the sintering temperature is 1373-2073K, the heating rate is 5-400K/min, the pressure is 10-40MPa, the heat preservation time is 5-400min, and mixing HfB2-TaSi₂the-SiC oxidation resistant coating is sintered on the carbon materialAnd (5) material surface. The invention applies the rapid densification sintering technology of SPS technology to HfB₂‑TaSi₂In the preparation of the-SiC oxidation resistant coating, HfB with high oxidation resistance and high compactness can be quickly prepared at a lower temperature₂‑TaSi₂-SiC oxidation resistant coating.

Description

A kind of preparation method of HfB2-TaSi2-SiC anti-oxidation coating on carbon material surface

technical field

The invention relates to the technical field of carbon materials, in particular to a preparation of HfB ₂ -TaSi ₂ -SiC anti-oxidation coating on the surface of carbon materials by a spark plasma sintering method.

Background technique

Carbon materials (C/C composites or graphite) are considered to be very promising in the aerospace field due to their excellent properties, such as ultra-high melting point (up to 3737K), good corrosion resistance, high strength, and low thermal diffusivity. s material. However, carbon materials are very easily oxidized when the temperature is above 673 K, which hinders their application. In order to solve this fatal shortcoming and prolong the life, the preparation of anti-oxidation coating on the surface of carbon materials is considered to be the most effective method.

In recent years, many scholars have carried out research on anti-oxidation coatings. The SiO ₂ formed by the oxidation of silicon-based ceramic coatings has good anti-oxidation properties, but with the increase of temperature, pores, cracks, etc. are prone to appear. defects, thereby reducing the antioxidant properties. Ultra-high temperature ceramics such as HfB ₂ , ZrB ₂ , TaSi ₂ , etc. have attracted extensive attention and are considered to be ideal materials for improving the service life of Si-based ceramic coatings because of their good high-temperature performance and compatibility with Si-based ceramics. Different oxidation products are formed, thereby forming a protective performance of a multiphase glass layer coating at high temperatures. Ren et al. in "Dynamicoxidation protective behaviors and mechanisms of HfB ₂ -20wt%SiC compositecoating for carbon materials." HfB ₂ -20%wtSiC composite coatings were prepared by liquid phase sintering method, and thermogravimetric analysis was carried out for different cyclic oxidation times , the results show that HfB ₂ -20% wtSiC has strong oxidation resistance under dynamic oxidation environment. Wang et al. in "A WSi ₂ -HfB ₂ -SiC coating for ultralong-time anti-oxidation at 1973 K." prepared WSi ₂ -HfB ₂ -SiC/SiC coating by in situ synthesis, and pre-oxidized at 1773K for 50h , After being oxidized at 1973K for 60h, good anti-oxidation performance was obtained, and a multiphase glass layer was formed at the same time. Yang et al. in "Effects of TaSi ₂ addition on room temperature mechanical properties of ZrB ₂ -20SiC composites." studied the effect of TaSi ₂ addition on the mechanical properties of ZrB ₂ -20SiC at room temperature. The Vickers hardness of TaSi ₂ , ZrB ₂ -20SiC composites is slightly reduced (about 1-2GPa). However, the flexural strength and fracture toughness are significantly improved. At the same time, with the increase of _TaSi content, the fracture site of the composite material changes from intragranular to grain boundary. This shows that TaSi ₂ has good viscosity at high temperature, and adding a certain amount of TaSi ₂ to the high temperature anti-oxidation coating acts as a binder to improve the protective effect.

At present, although embedding method, slurry method, in-situ synthesis method, liquid phase sintering and other methods are suitable for the preparation of ultra-high temperature ceramic anti-oxidation coatings, the above methods mainly use high temperature pressureless sintering to obtain coatings, and it is difficult to obtain high temperature ceramic anti-oxidation coatings. Dense ceramics, defects such as pores in the coating, provide a channel for oxygen to enter the interior of the coating, resulting in a significant reduction in the anti-oxidation performance. On the other hand, too high sintering temperature will lead to grain growth, which will affect the anti-oxidation effect, and also increase energy consumption and cost.

In recent years, spark plasma sintering (SPS) has attracted the attention of many scholars as a new low-temperature hot-pressing rapid sintering technology. The technology is sintered at a lower temperature by means of pressure to produce high density, fewer defects such as pores, strong bonding strength, and controllable components of the coating. To this end, Chen et al. in "Preparation of oxidationprotective MoSi ₂ -SiC coating on graphite using recycled waste MoSi ₂ by one-step spark plasma sintering method." Using waste MoSi heating element rods as raw materials, MoSi was prepared on a graphite substrate by SPS method ₂ -SiC coating, characterized the microstructure evolution and phase transition of the coating before and after oxidation, and studied the oxidation behavior of the coating in air at 1400 °C and 1200 °C, and tested the prepared coating by scratch test. Adhesive strength, the adhesive strength of MoSi ₂ -SiC coating is about 41.25N. At this stage, the spark plasma sintering method has not been widely used in the preparation of anti-oxidation coatings, and has a high research prospect. , Low defect HfB ₂ -TaSi ₂ -SiC oxidation resistant coating.

SUMMARY OF THE INVENTION

In order to overcome the above-mentioned deficiencies of the prior art, the present invention provides a preparation method of the HfB _{2 -TaSi 2} -SiC anti-oxidation coating on the surface of the carbon material at a lower sintering temperature. -The composition, thickness, sintering temperature and bonding strength between the carbon material and the coating of the TaSi ₂ -SiC coating can be adjusted, thereby significantly improving the oxidation resistance of the carbon material.

The technical scheme adopted in the present invention is as follows: a preparation method of HfB ₂ -TaSi ₂ -SiC anti-oxidation coating on the surface of carbon materials, weighing a certain proportion of HfB ₂ , TaSi ₂ and SiC powders, and putting them into a ball mill for ball milling Fully mixed, the carbon matrix is embedded with the fully mixed powder in the graphite mold, and the HfB ₂ -TaSi ₂ -SiC anti-oxidation coating is prepared on the surface of the carbon matrix by SPS technology.

Further, the concrete steps of the preparation method are as follows:

(1) Surface treatment of carbon substrate: polish the surface of the carbon substrate with sandpaper of different meshes, then clean it with alcohol, and finally dry it with a hair dryer;

(2) Mixing: first weigh a certain mass fraction of HfB ₂ powder (mass fraction of 5%-95%), TaSi ₂ powder (mass fraction of 5%-95%) and SiC powder (mass fraction of 5%-95%) HfB ₂ -TaSi ₂ -SiC composite homogeneous powder was prepared by ball milling, and the ball mill speed was 50-1000r/min, and the ball milling time was 0.5-10h;

(3) Molding: In the graphite mold, the carbon matrix treated in step (1) is embedded with the HfB ₂ -TaSi ₂ -SiC composite and uniform powder obtained in step (2), so that the powder is evenly coated. Buried carbon matrix, the thickness of the powder is about 0.1-3 times the thickness of the carbon matrix;

(4) SPS sintering: put the assembled sample mold into SPS for sintering, the sintering temperature is 1473-2273K, the heating rate is 5-400K/min, the pressure is 1-40MPa, and the holding time is 1-400min. A HfB ₂ -TaSi ₂ -SiC anti-oxidation coating was obtained on the surface of the substrate.

Compared with the prior art, the beneficial effects of the present invention are:

1. The HfB ₂ -TaSi ₂ -SiC anti-oxidation coating is prepared on the surface of carbon material by SPS technology. Due to the application of a certain pressure, the bonding strength between the coating and the carbon material is high, and it is not easy to fall off or even fail during service. , thereby increasing the service life of the coating.

2. The HfB ₂ -TaSi ₂ -SiC anti-oxidation coating prepared on the surface of carbon material by SPS technology has good compactness, the distribution of different phases is relatively uniform, and the whole is dense.

3. The composition of the HfB ₂ -TaSi ₂ -SiC anti-oxidation coating prepared on the surface of the carbon material by SPS technology can be adjusted, and the corresponding thickness and composition can be obtained according to actual needs.

4. The HfB ₂ -TaSi ₂ -SiC anti-oxidation coating prepared on the surface of carbon material by SPS technology has relatively low sintering temperature and short holding time, which can effectively inhibit grain growth.

5. Compared with the traditional sintering method without applying pressure, the content of each component and the thickness of the coating layer are difficult to control and the problems of low density with the carbon material are solved, and the object of the present invention is achieved.

6. The method used in the present invention is simple, fast and low in cost, so that the anti-oxidation performance of the carbon matrix is significantly improved, and the comprehensive performance of the coating is excellent, and has wide application prospects.

Description of drawings

1 is the surface XRD pattern of the 20%HfB ₂ -60% TaSi ₂ -20% SiC anti-oxidation coating on the surface of the carbon substrate prepared in Example 1 of the present invention;

2 is a cross-sectional SEM image of a 20%HfB ₂ -60% TaSi ₂ -20% SiC anti-oxidation coating on the surface of a carbon substrate prepared in Example 1 of the present invention;

3 is the surface XRD pattern of the 40%HfB ₂ -40% TaSi ₂ -20% SiC anti-oxidation coating on the surface of the carbon substrate prepared in Example 2 of the present invention;

4 is a cross-sectional SEM image of a 40% HfB ₂ -40% TaSi ₂ -20% SiC anti-oxidation coating on the surface of a carbon substrate prepared in Example 2 of the present invention;

5 is the surface XRD pattern of the 60%HfB ₂ -20% TaSi ₂ -20% SiC anti-oxidation coating on the surface of the carbon substrate prepared in Example 3 of the present invention;

6 is a cross-sectional SEM image of a 60% HfB ₂ -20% TaSi ₂ -20% SiC anti-oxidation coating on the surface of a carbon substrate prepared in Example 3 of the present invention;

Among them: 1-HfB ₂ , 2-TaSi ₂ , 3-SiC, 4-carbon matrix.

Detailed ways

In order to deepen the understanding of the present invention, the present invention will be further described below with reference to the accompanying drawings and embodiments. The embodiments are only used to explain the present invention and do not limit the protection scope of the present invention.

Example 1:

The phase analysis is shown in Figure 1, and the cross-sectional morphology is shown in Figure 2.

Step (1): Surface treatment of the carbon substrate: The surface of the carbon substrate is polished with sandpapers of different meshes, then cleaned with alcohol, and finally dried with a hair dryer.

Step (2): Mixing: firstly weigh powders with mass fractions of 20% HfB ₂ , 60% TaSi ₂ and 20% SiC, with a purity of ≥ 99.0% and a particle size of ≤ 55 μm, and then at a concentration of 400 r/min. The 20%HfB ₂ -60%TaSi ₂ -20%SiC composite powder was prepared by ball milling at a high speed for 4 hours.

Step (3): Molding: in the graphite mold, the carbon matrix treated in step (1) is embedded with the HfB ₂ -TaSi ₂ -SiC composite powder obtained in step (2) to make the powder The carbon matrix is evenly embedded, and the thickness of the powder is about 0.7 times the thickness of the carbon matrix.

Step (4): SPS technology: put the mold with the sample loaded into the spark plasma sintering furnace for sintering treatment. The sintering parameters are: sintering at 848K for 1s, rapidly heating to 873K, then holding for 2min, and heating to 1773K within 3min After holding for 10min, the heating rate was 300K/min, the pressure was 30MPa, and the sintering time was 901s. At this time, the 20%HfB ₂ -60%TaSi ₂ -20%SiC anti-oxidation coating on the surface of the carbon substrate was prepared.

Example 2:

The phase analysis is shown in Figure 3, and the cross-sectional morphology is shown in Figure 4.

Step (1): Surface treatment of the carbon substrate: The surface of the carbon substrate is polished with sandpapers of different meshes, then cleaned with alcohol, and finally dried with a hair dryer.

Step (2): Mixing: firstly weigh powders with mass fractions of 40% HfB ₂ , 40% TaSi ₂ and 20% SiC, with a purity of ≥99.0% and a particle size of ≤55 μm. The 40%HfB ₂ -40% TaSi ₂ -20% SiC composite powder was prepared by ball milling at high speed for 3 hours.

Step (3): Molding: in the graphite mold, the carbon matrix treated in step (1) is embedded with the HfB ₂ -TaSi ₂ -SiC composite powder obtained in step (2) to make the powder The carbon matrix is evenly embedded, and the thickness of the powder is about 0.6 times the thickness of the carbon matrix.

Step (4): SPS technology: put the mold with the sample loaded into the spark plasma sintering furnace for sintering treatment. The sintering parameters are: sintering at 848K for 1s, rapidly heating to 873K, then holding for 2min, and heating to 1673K within 5min After holding for 20min, the heating rate was 160K/min, the pressure was 20MPa, and the sintering time was 1621s. At this time, the 40%HfB ₂ -40%TaSi ₂ -20%SiC anti-oxidation coating on the surface of the carbon substrate was prepared.

Example 3:

The phase analysis is shown in Figure 5, and the cross-sectional morphology is shown in Figure 6.

Step (1): Surface treatment of the carbon substrate: The surface of the carbon substrate is polished with sandpapers of different meshes, then cleaned with alcohol, and finally dried with a hair dryer.

Step (2): Mixing: firstly weigh powders with mass fractions of 60% HfB ₂ , 20% TaSi ₂ and 20% SiC, the purity is ≥ 99.0% and the particle size is ≤ 55μm, and then the powder is 300 r/min. The 60%HfB ₂ -20%TaSi ₂ -20%SiC composite powder was prepared by ball milling at a rotational speed for 6 hours.

Step (3): Molding: in the graphite mold, the carbon matrix treated in step (1) is embedded with the HfB ₂ -TaSi ₂ -SiC composite powder obtained in step (2) to make the powder The carbon matrix is evenly embedded, and the thickness of the powder is about 0.8 times the thickness of the carbon matrix.

Step (4): SPS technology: put the mold with the sample loaded into the spark plasma sintering furnace for sintering treatment. The sintering parameters are: sintering at 848K for 1 s, rapidly heating to 873K, then holding for 5 minutes, and heating to 1873K within 4 minutes After holding for 30min, the heating rate was 250K/min, the pressure was 10MPa, and the sintering time was 2341s. At this time, the 60%HfB ₂ -20%TaSi ₂ -20%SiC anti-oxidation coating on the surface of the carbon substrate was prepared.

The embodiment of the present invention announces the preferred embodiment, but is not limited to this, those of ordinary skill in the art can easily understand the spirit of the present invention according to the above-mentioned embodiment, and make different extensions and changes, However, as long as they do not depart from the spirit of the present invention, they are all within the protection scope of the present invention.

Claims (6)

1. A preparation method of HfB ₂ -TaSi ₂ -SiC anti-oxidation coating on the surface of carbon material, which is characterized in that: weigh HfB ₂ , TaSi ₂ , SiC powder according to a certain proportion and put them into a ball mill to fully mix them , the carbon material is embedded with fully mixed powder in the graphite mold, and the HfB ₂ -TaSi ₂ -SiC anti-oxidation coating is synthesized on the surface of the carbon material by using the SPS rapid densification and sintering technology. 2. carbon material surface preparation HfB ₂ -TaSi ₂ -SiC anti-oxidation coating according to claim 1, its concrete steps are as follows: (1) Surface treatment of carbon substrate: Polish the surface of carbon substrate with sandpaper of different meshes, then clean it with alcohol, and finally put it into an oven to dry; (2) Mixing: Firstly, according to the proportion of ingredients, weigh a certain mass of HfB ₂ powder, TaSi ₂ powder and SiC powder respectively, and then use a ball mill to fully mix the three powders to obtain a composite uniform HfB ₂ - TaSi ₂ -SiC powder; (3) Molding: In the graphite mold, the carbon matrix treated in step (1) is embedded with the HfB ₂ -TaSi ₂ -SiC composite and uniform powder obtained in step (2), so that the powder is evenly coated. Buried carbon matrix; (4) SPS sintering: put the assembled sample mold into a plasma sintering furnace for sintering, the sintering temperature is 1373-2073K, the heating rate is 5-400K/min, the pressure is 5-40MPa, and the holding time is 5- After 400 min, the HfB ₂ -TaSi ₂ -SiC anti-oxidation coating was obtained on the surface of the carbon substrate. 3. The preparation method for preparing HfB ₂ -TaSi ₂ -SiC anti-oxidation coating on the surface of a carbon material according to claim 2, characterized in that: the HfB ₂ , TaSi ₂ and SiC powder described in the above step (2) The purity of the material is greater than or equal to 99.0%, and the particle size is less than or equal to 55 μm. 4 . The preparation method of the HfB ₂ -TaSi ₂ -SiC anti-oxidation coating on the surface of a carbon material according to claim 2 , wherein the carbon material is graphite or C/C composite material. 5 . 5 . The method for preparing a HfB ₂ -TaSi ₂ -SiC anti-oxidation coating on a carbon material surface according to claim 2 , wherein: in the above step (2), the HfB ₂ -TaSi ₂ -SiC composite powder is The mass fraction of HfB ₂ is 5%-95%, of which the mass fraction of TaSi ₂ is 5%-95%, the mass fraction of SiC is 5%-95%, the speed of the ball mill is 50-1000r/min, and the ball milling time is 0.5-10h. 6 . The method for preparing a HfB ₂ -TaSi ₂ -SiC anti-oxidation coating on the surface of a carbon material according to claim 2 , wherein: in the above step (3), the HfB ₂ - The thickness of the TaSi ₂ -SiC composite powder is about 0.1-3 times the thickness of the carbon matrix.

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