Preparation method of C / C composite material high-entropy ceramic coating

Abstract

According to the preparation method of the C / C composite material high-entropy ceramic coating, a spark plasma sintering method is adopted, the high-entropy ceramic coating is prepared on the surface of the C / C composite material by sintering refractory carbide mixed powder with the equal atomic ratio within a short time, heat damage to a matrix is reduced, and the high-entropy ceramic coating is prepared on the surface of the C / C composite material. And the preparation method of the C / C composite material ceramic coating is expanded. The problems that an existing C / C composite material anti-oxidation coating is complex in preparation process, large in heat damage and limited in coating protection temperature are solved, and the preparation efficiency of the refractory ceramic coating is improved.

Description

Technical Field

[0001] The present invention relates to the field of preparation of ultra-high temperature thermal protection structures, and in particular to a method for preparing a high entropy ceramic coating of a C / C composite material. The present invention can improve the preparation efficiency of the thermal protection ceramic coating of the C / C composite material and reduce the thermal damage to the C / C composite material. Background Art

[0002] With the rapid development of aerospace technology, higher requirements are put forward for rocket propulsion technology. As a key component of the thrust chamber on a rocket engine, the material used for the nozzle must have the characteristics of light weight, high strength, high temperature resistance, and ablation resistance. Carbon fiber reinforced carbon-based composite materials (C / C composite materials) are high-performance materials that have been rapidly developed and applied in the aerospace field in recent years. They have the characteristics of light specific gravity, strong thermal conductivity, excellent thermal shock resistance, friction and wear resistance, and good high temperature performance. They are one of the best choices for the production and preparation of aerospace engine nozzle materials. However, C / C composite materials will oxidize at temperatures above 350°C, causing a sharp decline in their various properties. Anti-oxidation coating technology can isolate C / C composite materials from direct contact with oxygen atmosphere, achieve longer time and higher temperature anti-oxidation protection, thereby improving the anti-oxidation, high temperature resistance, and ablation resistance of C / C composite materials. It is currently the most widely used and mature anti-oxidation protection technology.

[0003] Ceramic coating is the most intensively studied anti-oxidation coating for C / C composites. Silicon-based ceramic coating is the most widely used ceramic coating, but its effective protection temperature is below 1500℃, and it is difficult to form effective protection for ultra-high temperature environments above 1800℃. In order to meet the more stringent high-temperature service requirements of aerospace engine nozzle materials, chemical vapor deposition technology and plasma spraying technology are mainly used at home and abroad to prepare single-component refractory metal carbide ceramic coatings such as HfC, ZrC, and TaC on the surface of C / C composites. Chemical vapor deposition technology has the disadvantages of long preparation cycle, low deposition rate, and complex process, while the coating prepared by plasma spraying technology has a high porosity, weak interface bonding between the coating and the substrate, and the coating is prone to peeling and cracking during high-temperature thermal cycles. In addition, most of the current refractory metal carbide ceramic coatings are single-component, and there are few studies and reports on multi-component refractory high-entropy ceramic coatings with better mechanical properties and high-temperature stability.

[0004] Chinese patent CN 108530110 A discloses an ultra-high temperature ceramic coating of a C / C composite material and a preparation method thereof. The method first prepares a layer of SiC coating on the surface of the C / C composite material by a chemical vapor reaction method in a high-temperature furnace, and then uses a plasma sprayer to spray ultra-high temperature ceramic powder (one or more of SiC, ZrC, HfC, TaC, TiC, ZrB2, HfB2, TaB2, TiB2) on the surface of the SiC coating, thereby forming a composite coating with an inner layer of SiC and an outer layer of ultra-high temperature ceramic. The preparation process of this method is complicated, and two different processes are used to prepare the inner and outer protective coatings. When preparing the SiC inner coating, it is necessary to heat it at above 2000℃ for 2h, and then use plasma repeated spraying to prepare the outer layer of ultra-high temperature ceramic coating. Long-term heating and high energy density heat sources are likely to cause greater thermal damage to the C / C composite material. In addition, the effective protection temperature of the prepared SiC inner coating is low (below 1500℃), and it is difficult to form effective ultra-high temperature protection. Summary of the invention

[0005] In order to overcome the deficiencies of the prior art, the present invention provides a method for preparing a high-entropy ceramic coating of a C / C composite material. The present invention provides a novel method for preparing a ceramic coating and a high-entropy ceramic coating prepared using a C / C composite material. The purpose of the present invention is to solve the problems of the existing C / C composite material anti-oxidation coating, such as complex preparation process, long heating time, and easy thermal damage, and to propose a novel method for preparing a ceramic coating. A high-entropy ceramic coating is prepared in situ on the surface of a C / C composite material by sintering a carbide mixed powder in a spark plasma sintering furnace.

[0006] The present invention provides a method for preparing a high entropy ceramic coating on the surface of a C / C composite material in a relatively short time, which solves the problems of complex preparation process, large thermal damage and limited coating protection temperature of the existing C / C composite material anti-oxidation coating, and improves the preparation efficiency of the refractory ceramic coating. The present invention adopts a spark plasma sintering method, and realizes the preparation of a high entropy ceramic coating on the surface of a C / C composite material by sintering a mixed powder of refractory carbides with an equal atomic ratio in a short time, thereby reducing the thermal damage to the substrate and expanding the preparation method of the C / C composite material ceramic coating.

[0007] The technical solution adopted by the present invention to solve the technical problem comprises the following steps:

[0008] 1) weighing carbide powder according to the ratio of each component in the high entropy ceramic, and ball-milling the weighed powder to make it uniform;

[0009] 2) Weighing the required carbide mixed powder and evenly spreading the carbide mixed powder on the surface of the C / C composite material;

[0010] 3) placing the C / C composite material with the spread carbide mixed powder into a graphite mold and placing it in a spark plasma sintering furnace for pre-pressing;

[0011] 4) After pre-pressing, continue to heat, keep warm and cool in the spark plasma sintering furnace to complete the sintering of the carbide mixed powder;

[0012] 5) The sintered C / C composite material high entropy ceramic coating obtained in step 4) is surface ground, polished and dried to obtain a final C / C composite material high entropy ceramic coating.

[0013] Furthermore, in step 1), the ratio of each component in the (ZrHfNbTa)C high entropy ceramic coating is Zr:Hf:Nb:Ta=1:1:1:1, carbide powders are weighed in equal molar ratios, and the carbide powders include ZrC powder, HfC powder, NbC powder and TaC powder. The carbide powders weighed in equal molar ratios are mixed, and the mixed carbide powders are placed in a ball mill jar, and put into a planetary ball mill for ball milling for 12 to 24 hours to make the mixed powder evenly ball milled.

[0014] Furthermore, in step 2), 0.4-0.6 g of mixed carbide powder is weighed from the ball-milled powder using an electronic balance and sieved through a sieve having a mesh size of 200-400 meshes, and the mixed carbide powder is evenly spread on the surface of a C / C composite material having a specification of 10 mm×10 mm×5 mm.

[0015] Further, in step 3), the graphite mold has a specification of Φ20 mm and is pre-pressed in a spark plasma sintering furnace at a pre-pressing pressure of 5 to 10 kN for 10 to 20 min at room temperature;

[0016] Furthermore, the specific steps of step 4) are:

[0017] The carbide mixed powder is sintered in a spark plasma sintering furnace with a sintering pressure of 5 to 10 kN, a heating rate of 50 to 100°C / min, a sintering temperature of 1500 to 2000°C, a sintering time of 10 to 30 min, and a cooling rate of 50 to 100°C / min to obtain a C / C composite material (ZrHfNbTa)C high entropy ceramic coating.

[0018] Furthermore, in step 5), the prepared C / C composite material high entropy ceramic coating is ground and polished using sandpaper with a mesh size of 200#, and the coating surface is dried using a hair dryer.

[0019] At the same time, the present invention also provides a C / C composite material high entropy ceramic coating, which is manufactured by the above method.

[0020] The C / C composite material high-entropy ceramic coating prepared by the method includes, in addition to (ZrHfNbTa)C, a high-entropy ceramic coating composed of any four or more of the refractory metal elements Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, and W and the C element.

[0021] The beneficial effects of the present invention are:

[0022] 1. In current technology, most ceramic coatings are SiC coatings, which are difficult to protect C / C composite materials in ultra-high temperature environments above 1800°C; and most of the current refractory metal carbide ceramic coatings are single-component, and there is little research on the preparation of high-entropy ceramic coatings with better mechanical properties and high-temperature stability. The present invention provides a method for preparing a high-entropy ceramic coating.

[0023] 2. In the background technology, a plasma spraying method is used to prepare an ultra-high temperature ceramic coating. The heat source energy density is high, and the C / C composite material needs to be sprayed repeatedly, which easily causes great thermal damage to the C / C composite material. The present invention provides a novel method for preparing an ultra-high temperature ceramic coating, namely, a spark plasma sintering process, which can promote the rapid sintering and forming of the coating under the assistance of pulsed direct current, with a short heating time and less thermal damage to the C / C composite material.

[0024] 3. The present invention also has reference significance for the preparation of single-component refractory carbide ceramic coatings of C / C composite materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the assembly of the graphite mold of the present invention;

[0026] Figure 2 is the spark plasma sintering heating curve of the present invention;

[0027] Figure 3 The backscattered electron images of the C / C composite material high entropy ceramic coating prepared by the present invention under a scanning electron microscope, wherein (a) is the overall morphology of the coating, (b) is the morphology of the interface between the coating and the substrate, and (c) is the magnified morphology of the interface between the coating and the substrate;

[0028] Figure 4 This is an EDS element surface distribution image of the C / C composite high entropy ceramic coating prepared in the present invention under a scanning electron microscope. DETAILED DESCRIPTION

[0029] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0030] A method for preparing a C / C composite material high entropy ceramic coating comprises the following steps:

[0031] 1) According to the ratio of each component in the final (ZrHfNbTa)C high entropy ceramic coating to be prepared, the components are Zr:Hf:Nb:Ta=1:1:1:1, and the carbide mixed powder is weighed in an equal molar ratio. The carbide mixed powder is ZrC powder, HfC powder, NbC powder and TaC powder. The total weight of the carbide mixed powder is 100g. The mixed carbide mixed powder is placed in a ball mill jar and placed in a planetary ball mill for 12 hours to make it ball-milled uniformly;

[0032] 2) Weigh 0.5 g of carbide mixed powder from the ball-milled powder using an electronic balance, the mesh number of the sieve is 200 mesh, and evenly spread the carbide mixed powder on the surface of the C / C composite material with a specification of 10 mm×10 mm×5 mm;

[0033] 3) Place the C / C composite material with the spread carbide mixed powder into a graphite mold. The specification of the graphite mold is Φ20mm. The assembly diagram is as shown in Figure 1 As shown, the assembled graphite mold is pre-pressed in a spark plasma sintering furnace with a pre-pressing pressure of 5 kN for 10 min at room temperature;

[0034] 4) The mixed carbide powder is sintered in a spark plasma sintering furnace with a sintering pressure of 5 kN, a heating rate of 100 °C / min, a sintering temperature of 2000 °C, a sintering time of 30 min, a cooling rate of 100 °C / min, and a spark plasma sintering heating curve as shown in FIG. Figure 2 As shown, a C / C composite material (ZrHfNbTa)C high entropy ceramic coating is obtained;

[0035] 5) The prepared C / C composite material high entropy ceramic coating was ground and polished using 200# sandpaper, and the coating surface was dried using a hair dryer.

[0036] In order to test the quality of the C / C composite material high entropy ceramic coating prepared by the preparation method of the present invention, the prepared C / C composite material high entropy ceramic coating was cut along the direction perpendicular to the interface bonding to prepare a metallographic sample. The coating structure in the joint was observed under a scanning electron microscope. Figure 3 As shown, the coating thickness is about 500μm, the coating is continuous and dense as a whole, without pores or cracks, and the interface between the coating and the substrate is tightly bonded. EDS point analysis was performed on different locations of the coating structure, and the results are shown in Table 1:

[0037] Table 1 Figure 3 (b) EDS analysis results of each location / area

[0038]

[0039] Table 1 Figure 3(b) shows the EDS analysis results of each position / region in the high entropy ceramic coating of C / C composite material; it can be seen that the atomic ratio of Zr, Hf, Nb, and Ta elements in each position / region is basically close to 1:1:1:1, indicating that a relatively uniform (ZrHfNbTa)C high entropy ceramic coating structure is prepared on the surface of C / C composite material. Spark plasma sintering technology can be used to prepare a high entropy ceramic coating with uniform composition on the surface of C / C composite material. EDS characterization of the surface distribution of each element in the coating, such as Figure 4 As shown, the distribution of Zr, Hf, Nb and Ta elements is very uniform.

[0040] The method of the present invention can prepare a high-entropy ceramic coating on the surface of a C / C composite material in a relatively short time, reduce the thermal damage of the preparation process to the C / C composite material, and can also serve as a reference for the preparation of other types of single-component refractory metal carbide ceramic coatings and multi-component high-entropy ceramic coatings of the C / C composite material, thereby realizing the ultra-high temperature application of the anti-oxidation coating of the C / C composite material above 1800°C.

Claims

1. A method for preparing a C / C composite material high entropy ceramic coating, characterized in that The steps include: 1) weighing carbide powder according to the ratio of each component in the high entropy ceramic, and ball-milling the weighed powder to make it uniform; 2) Weighing the required carbide mixed powder and evenly spreading the carbide mixed powder on the surface of the C / C composite material; 3) placing the C / C composite material with the spread carbide mixed powder into a graphite mold and placing it in a spark plasma sintering furnace for pre-pressing; 4) After pre-pressing, continue to heat, keep warm and cool in the spark plasma sintering furnace to complete the sintering of the carbide mixed powder; 5) The sintered C / C composite material high entropy ceramic coating obtained in step 4) is surface ground, polished and dried to obtain a final C / C composite material high entropy ceramic coating.

2. The method for preparing a C / C composite material high entropy ceramic coating according to claim 1, characterized in that: In step 1), the ratio of each component in the (ZrHfNbTa)C high entropy ceramic coating is Zr:Hf:Nb: Ta=1:1:1:1, weigh carbide powders in equal molar ratios, the carbide powders include ZrC powder, HfC powder, NbC powder and TaC powder, mix the carbide powders in equal molar ratios, put the mixed carbide powders in a ball mill jar, put them in a planetary ball mill and ball mill them for 12 to 24 hours to make the mixed powders evenly ball milled.

3. The method for preparing a C / C composite material high entropy ceramic coating according to claim 1, characterized in that: In step 2), 0.4-0.6 g of mixed carbide powder is weighed from the ball-milled powder using an electronic balance and sieved through a sieve with a mesh size of 200-400 meshes, and the mixed carbide powder is evenly spread on the surface of a C / C composite material with a specification of 10 mm×10 mm×5 mm.

4. The method for preparing a C / C composite material high entropy ceramic coating according to claim 1, characterized in that: In step 3), the graphite mold has a specification of Φ20 mm and is pre-pressed in a spark plasma sintering furnace with a pre-pressing pressure of 5 to 10 kN for 10 to 20 minutes at room temperature.

5. The method for preparing a C / C composite material high entropy ceramic coating according to claim 1, characterized in that: The specific steps of step 4) are: The carbide mixed powder is sintered in a spark plasma sintering furnace with a sintering pressure of 5 to 10 kN, a heating rate of 50 to 100°C / min, a sintering temperature of 1500 to 2000°C, a sintering time of 10 to 30 min, and a cooling rate of 50 to 100°C / min to obtain a C / C composite material (ZrHfNbTa)C high entropy ceramic coating.

6. The method for preparing a C / C composite material high entropy ceramic coating according to claim 1, characterized in that: In step 5), the prepared C / C composite material high entropy ceramic coating is ground and polished using sandpaper with a mesh size of 200#, and the coating surface is dried using a hair dryer.

7. A C / C composite material high entropy ceramic coating, characterized in that: The C / C composite material high entropy ceramic coating is manufactured by the method described in claims 1-6.

8. The C / C composite material high entropy ceramic coating according to claim 7, characterized in that: The C / C composite material high entropy ceramic coating, in addition to (ZrHfNbTa)C, also includes a high entropy ceramic coating composed of any four or more of the refractory metal elements Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, and W and the C element.

Images