CN102093083B - Preparation method for ablation-resistant coating made of carbon/carbon composite material HfC - Google Patents

Abstract

The invention discloses a method for preparing a carbon/carbon composite HfC anti-ablation coating, which comprises the following steps: 1. Grinding and polishing the carbon/carbon composite material, cleaning and drying; 2. preparing slurry by ball milling; 3. 1. Evenly brush or spray paint slurry on the surface of the carbon/carbon composite material; 4. Sinter under the protection of inert gas to prepare the HfC anti-ablation coating of the carbon/carbon composite material. The present invention overcomes the damage to carbon fibers caused by the reaction of _HfO2 and C in the matrix modification process, and the addition of rare earth metal oxides and AlN improves the diffusion and permeation ability of Hf, making the coating uniform, dense and crack-free, and at the same time making the coating A gradient coating with a composition transition between the carbon/carbon composite material reduces the residual stress of the coating, improves the bonding strength of the HfC coating and the carbon/carbon composite material, and also improves the high temperature strength of the HfC coating.

Description

Preparation method of carbon/carbon composite material HfC anti-ablation coating

technical field

The invention belongs to the technical field of high-temperature-resistant materials, and in particular relates to a preparation method of a carbon/carbon composite HfC anti-ablation coating.

Background technique

Carbon/carbon composite material is currently the only material that can maintain high mechanical properties above 2000 °C. It has a series of excellent properties such as low density, high specific strength, high specific modulus, low thermal expansion coefficient and thermal shock resistance, especially with The unique property that the strength does not decrease but increases with the increase of temperature has unique advantages as an ultra-high temperature thermal structural material. However, carbon/carbon composites have poor ablation resistance in high-temperature oxidation, high-velocity gas flow, and high-speed particle flow scour environments. The main methods to improve the ablation resistance of carbon/carbon composites are: (1) matrix modification, that is, adding refractory carbides to the matrix of carbon/carbon composites; (2) preparing anti-ablation coatings, that is, adding Preparation of refractory carbide, silicide or boride composite coating on the surface of /carbon composite material.

Li Shuping et al. (Li Shuping, Li Kezhi, Guo Lingjun, He Yonggang, Research on Ablation Performance of HfC Modified C/C Composite Integral Throat Liner, Journal of Inorganic Materials, 2008, 23(6): 1155-1158) used HfOCl ₂ ·8H ₂ O ethanol solution impregnated the carbon preform, and used heat treatment to convert HfOCl ₂ into HfO ₂ and then into HfC to realize the modification of the carbon matrix and improve the ablation resistance of the C/C composite. However, the process of _HfO2 and carbon reaction to generate HfC damages the carbon fibers and reduces the mechanical properties of C/C composites.

Hou Genliang et al. (Hou Genliang, Su Xunjia, Wang Yanbin, Zhou Xiaobo, Preparation of anti-ablation HfC coating on C/C composite materials, Journal of Aeronautical Materials, 2009, 29(1): 77-80) used HfOCl ₂ solution to coat composite The material was then heat-treated at 1800 °C for 2 h under an argon atmosphere to form an HfC coating. However, the HfC coating prepared by this method not only has cracks but also is porous, which cannot effectively improve the ablation resistance of carbon/carbon composites.

Wang Depeng et al. (Wang Depeng, Su Xunjia, Hou Genliang, Preparation and Performance Analysis of HfC Ceramic Coating, Guangdong Journal of Nonferrous Metals, 2006, 16(1): 19-21) prepared HfC coating by plasma spraying method. However, since HfC only gasifies and decomposes above the melting point but does not melt, the metal bonding layer must be prepared first by using the plasma spraying method to prepare the HfC coating, and the metal bonding layer cannot be applied under high temperature conditions above 1650 °C. , the HfC coating has microporosity and low bonding strength.

The United States Ultramet company uses chemical vapor deposition (CVD) method to prepare HfC coating. However, using this method to prepare HfC coatings, the reaction product HCl will seriously corrode the equipment, and the bonding strength between the coating and the substrate is low.

Contents of the invention

The technical problem to be solved by the present invention is to provide a method for preparing a carbon/carbon composite HfC anti-ablation coating for the above-mentioned deficiencies in the prior art. The prepared HfC anti-ablation coating is dense and uniform, and has high bonding strength with carbon/carbon composites.

In order to solve the above-mentioned technical problems, the technical solution adopted in the present invention is: a kind of preparation method of carbon/carbon composite material HfC anti-ablation coating, it is characterized in that, this method comprises the following steps:

(1) After polishing the carbon/carbon composite material, ultrasonically clean it in an organic solvent for 20-60 minutes, and then dry it in an oven;

(2) Add Hf powder, rare earth metal oxide powder, AlN powder and graphite powder into a ball mill jar and mix to obtain a mixture, then add ethyl acetate and nitro varnish into the ball mill jar, and ball mill and mix for 24h to 72h to prepare a slurry ; The mass percentage of Hf powder in the mixture is 70% to 89%, the mass percentage of rare earth metal oxide powder is 5% to 15%, the mass percentage of AlN powder is 1% to 5%, and the graphite powder is the balance; The sum of the mass of the ethyl acetate and the nitro varnish is 50% to 150% of the mass of the mixture; the mass ratio of the ethyl acetate and the nitro varnish is 1 to 2:1;

(3) Evenly brush or spray the slurry described in step (2) on the surface of the carbon/carbon composite material after drying in step (1), and form a coating with a thickness of not less than 50 μm on the surface, and then place drying in an oven;

(4) Put the carbon/carbon composite material dried in step (3) into a graphite crucible, and place them together in a vacuum furnace. Raise the temperature to 1550°C to 1900°C for sintering, then keep it warm for 2h to 3h, turn off the power and cool to room temperature to obtain a carbon/carbon composite material HfC anti-ablation coating.

The grinding and polishing system described in the above step (1) is: sequentially use No. 400 SiC water-grinding paper, No. 800 SiC water-grinding paper, and No. 1200 SiC water-grinding paper to polish and polish.

The organic solvent described in the above step (1) is acetone or ethanol; the temperature of the oven described in the above step (1) is 100°C to 200°C.

The rare earth metal oxide powder described in the above step (2) is Y ₂ O ₃ powder, Er ₂ O ₃ powder, Sc ₂ O ₃ powder, Lu ₂ O ₃ powder, La ₂ O ₃ powder, Yb ₂ O ₃ powder, One or more of Ce ₂ O ₃ powder and Gd ₂ O ₃ powder.

The ball milling jar described in the above step (2) is an alumina ball milling jar or a polyurethane ball milling jar.

The thickness of the coating in the above step (3) is 50 μm to 1500 μm; the temperature of the oven in the step (3) is 100° C. to 200° C.

The inert gas described in the above step (4) is argon with a mass purity not less than 99.9%.

Compared with the prior art, the present invention has the following advantages: the present invention prepares the HfC coating on the surface of the carbon/carbon composite material through the reaction of Hf and C through slurry coating and inert atmosphere protection sintering, which overcomes the _HfO2 in the matrix modification process The reaction with C damages the carbon fiber, the addition of rare earth metal oxides and AlN improves the diffusion ability of Hf, makes the coating uniform, dense and free of cracks, and at the same time forms a gradient coating with composition transition between the coating and the substrate , which reduces the residual stress of the coating, improves the bonding strength between the HfC coating and the substrate, and also improves the high temperature strength of the HfC coating.

The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments.

Description of drawings

Figure 1 is the X-ray diffraction pattern of the carbon/carbon composite material HfC anti-ablation coating prepared in Example 1 of the present invention.

Fig. 2 is a cross-sectional SEM photo of the carbon/carbon composite material HfC anti-ablation coating prepared in Example 1 of the present invention.

Fig. 3 is a scanning electron micrograph of the surface of the carbon/carbon composite material HfC anti-ablation coating prepared in Example 1 of the present invention.

Detailed ways

Example 1

(1) Grind and polish the carbon/carbon composite material with No. 400, No. 800, and No. 1200 SiC water-grinding paper in sequence, then ultrasonically clean it in acetone for 20 minutes, and put it in an oven at a temperature of 100°C to dry;

(2) Add Hf powder, rare earth metal oxide powder, AlN powder and graphite powder into an alumina ball mill jar and mix to obtain a mixture, then add ethyl acetate and nitro varnish into the ball mill jar, and ball mill and mix for 24 hours to prepare a slurry ; The mass percentage of Hf powder in the mixture is 70%, the mass percentage of rare earth metal oxide powder is 15%, the mass percentage of AlN powder is 5%, graphite powder is surplus, and described rare earth metal oxide powder is La ₂ O ₃ powder, the sum of the mass of said ethyl acetate and nitro varnish is 50% of the mixture mass; the mass ratio of said ethyl acetate and nitro varnish is 2:1;

(3) Evenly brush the slurry on the surface of the dried carbon/carbon composite material, and form a coating with a thickness of 50 μm on the surface, and then place it in an oven with a temperature of 150 ° C for drying;

(4) Put the dried carbon/carbon composite material into a graphite crucible, and place them together in a vacuum furnace. Under the protection of argon gas with a mass purity of not less than 99.9%, the temperature is raised to Sintering at 1550°C, followed by heat preservation for 3 hours, power off and cooling to room temperature to obtain a HfC ablation-resistant coating with high bonding strength with carbon/carbon composite materials, uniform density and no cracks.

The X-ray diffraction pattern of the carbon/carbon composite HfC anti-ablation coating prepared in this embodiment is shown in Figure 1, and the crystal planes of the diffraction peaks in the figure correspond to (111), (200), (220), and (311), (222), (400) crystal planes.

The cross-sectional scanning electron microscope photo of the carbon/carbon composite material HfC anti-ablation coating prepared in this example is shown in Figure 2, and the HfC anti-ablation coating is well combined with the carbon/carbon composite material matrix.

The SEM photo of the surface of the carbon/carbon composite material HfC anti-ablation coating prepared in this example is shown in Figure 3. The HfC anti-ablation coating is dense and has no cracks.

Example 2

This example is the same as Example 1, except that the rare earth metal oxide powder used is Er ₂ O ₃ , Sc ₂ O ₃ , Lu ₂ O ₃ , La ₂ O ₃ , Yb ₂ O ₃ , Ce ₂ O ₃ and Gd ₂ O ₃ , or Y ₂ O ₃ , Er ₂ O ₃ , Sc ₂ O ₃ , Lu ₂ O ₃ , La ₂ O ₃ , Yb ₂ O ₃ , Ce ₂ O ₃ and Gd ₂ At least two of O ₃ .

The HfC anti-ablation coating prepared in this example has a high bonding strength with the carbon/carbon composite material, and the coating is dense and uniform without cracks.

Example 3

(1) Grind and polish the carbon/carbon composite material with No. 400, No. 800, and No. 1200 SiC water-grinding paper in sequence, then ultrasonically clean it in ethanol for 40 minutes, and dry it in an oven at a temperature of 200 ° C;

(2) adding Hf powder, rare earth metal oxide powder, AlN powder and graphite powder into a polyurethane ball mill tank and mixing to obtain a mixture, then adding ethyl acetate and nitrovarnish to the ball mill tank, and ball milling and mixing for 48 hours to prepare a slurry; The mass percentage of Hf powder in the mixture is 89%, the mass percentage of rare earth metal oxide powder is 5%, the mass percentage of AlN powder is 1%, graphite powder is the balance, and described rare earth metal oxide powder is _{Sc2 O3} powder, the sum of the quality of described ethyl acetate and nitro varnish is 100% of mixture quality; The mass ratio of described ethyl acetate and nitro varnish is 1: 1;

(3) Evenly brush the slurry on the surface of the dried carbon/carbon composite material, and form a coating with a thickness of 1500 μm on the surface, and then place it in an oven with a temperature of 200 ° C for drying;

(4) Put the dried carbon/carbon composite material into a graphite crucible, place them together in a vacuum furnace, and raise the temperature at a rate of 25°C/min to Sintering at 1900°C, followed by heat preservation for 2 hours, power off and cooling to room temperature to obtain a HfC ablation-resistant coating with high bonding strength with carbon/carbon composite materials, uniform density and no cracks.

Example 4

This example is the same as Example 3, except that the rare earth metal oxide powder used is Y ₂ O ₃ , Er ₂ O ₃ , Lu ₂ O ₃ , La ₂ O ₃ , Yb ₂ O ₃ , Ce ₂ O ₃ and Gd ₂ O ₃ , or Y ₂ O ₃ , Er ₂ O ₃ , Sc ₂ O ₃ , Lu ₂ O ₃ , La ₂ O ₃ , Yb ₂ O ₃ , Ce ₂ O ₃ and Gd ₂ At least two of O ₃ .

The HfC anti-ablation coating prepared in this example has a high bonding strength with the carbon/carbon composite material, and the coating is dense and uniform without cracks.

Example 5

(1) Grind and polish the carbon/carbon composite material with No. 400, No. 800, and No. 1200 SiC water-grinding paper in sequence, then ultrasonically clean it in acetone for 60 minutes, and dry it in an oven at a temperature of 150°C;

(2) Add Hf powder, rare earth metal oxide powder, AlN powder and graphite powder into an alumina ball mill tank and mix to obtain a mixture, then add ethyl acetate and nitro varnish to the ball mill tank, and ball mill and mix for 72 hours to prepare a slurry ; The mass percentage of Hf powder in the mixture is 80%, the mass percentage of rare earth metal oxide powder is 10%, the mass percentage of AlN powder is 3%, graphite powder is surplus, and described rare earth metal oxide powder is Ce ₂ O ₃ powder, the sum of the quality of said ethyl acetate and nitro varnish is 150% of the mixture quality; the mass ratio of said ethyl acetate and nitro varnish is 1.5:1;

(3) Evenly brush the slurry on the surface of the dried carbon/carbon composite material, and form a coating with a thickness of 800 μm on the surface, and then place it in an oven with a temperature of 100 ° C for drying;

(4) Put the dried carbon/carbon composite material into a graphite crucible, and place them together in a vacuum furnace. Under the protection of argon gas with a mass purity of not less than 99.9%, heat up to Sintering at 1725°C, followed by heat preservation for 2.5 hours, power off and cooling to room temperature to obtain a HfC ablation-resistant coating with high bonding strength with carbon/carbon composite materials, uniform density and no cracks.

Example 6

This example is the same as Example 5, except that the rare earth metal oxide powder used is Y ₂ O ₃ , Er ₂ O ₃ , Sc ₂ O ₃ , Lu ₂ O ₃ , La ₂ O ₃ , Yb ₂ O ₃ and Gd ₂ O ₃ , or Y ₂ O ₃ , Er ₂ O ₃ , Sc ₂ O ₃ , Lu ₂ O ₃ , La ₂ O ₃ , Yb ₂ O ₃ , Ce ₂ O ₃ and Gd ₂ At least two of O ₃ .

The HfC anti-ablation coating prepared in this example has a high bonding strength with the carbon/carbon composite material, and the coating is dense and uniform without cracks.

Claims (7)

1. a preparation method of carbon/carbon composite material HfC anti-ablation coating, is characterized in that, the method may further comprise the steps: (1) After polishing the carbon/carbon composite material, ultrasonically clean it in an organic solvent for 20-60 minutes, and then dry it in an oven; (2) Add Hf powder, rare earth metal oxide powder, AlN powder and graphite powder into a ball mill jar and mix to obtain a mixture, then add ethyl acetate and nitro varnish into the ball mill jar, and ball mill and mix for 24h to 72h to prepare a slurry ; The mass percentage of Hf powder in the mixture is 70% to 89%, the mass percentage of rare earth metal oxide powder is 5% to 15%, the mass percentage of AlN powder is 1% to 5%, and the graphite powder is the balance; The sum of the mass of the ethyl acetate and the nitro varnish is 50% to 150% of the mass of the mixture; the mass ratio of the ethyl acetate and the nitro varnish is 1 to 2:1; (3) Evenly brush or spray the slurry described in step (2) on the surface of the carbon/carbon composite material after drying in step (1), and form a coating with a thickness of not less than 50 μm on the surface, and then place drying in an oven; (4) Put the carbon/carbon composite material dried in step (3) into a graphite crucible, and place them together in a vacuum furnace. Raise the temperature to 1550°C to 1900°C for sintering, then keep it warm for 2h to 3h, turn off the power and cool to room temperature to obtain a carbon/carbon composite material HfC anti-ablation coating. 2. the preparation method of carbon/carbon composite material HfC anti-ablation coating according to claim 1, is characterized in that, the system of grinding and polishing described in step (1) is: use No. 400 SiC water sandpaper successively, 800 No. SiC water abrasive paper, No. 1200 SiC water abrasive paper for polishing. 3. the preparation method of carbon/carbon composite material HfC anti-ablation coating according to claim 1, is characterized in that, organic solvent described in step (1) is acetone or ethanol; Oven described in step (1) The temperature ranges from 100°C to 200°C. 4. the preparation method of carbon/carbon composite material HfC anti-ablation coating according to claim 1, is characterized in that, the rare earth metal oxide powder described in step (2) is Y ₂ O ₃ powder, Er ₂ O ₃ powder, Sc ₂ O ₃ powder, Lu ₂ O ₃ powder, La ₂ O ₃ powder, Yb ₂ O ₃ powder, Ce ₂ O ₃ powder and Gd ₂ O ₃ powder or one or more of them. 5. the preparation method of carbon/carbon composite material HfC anti-ablation coating according to claim 1, is characterized in that, the ball mill jar described in step (2) is alumina ball mill jar or polyurethane ball mill jar. 6. the preparation method of carbon/carbon composite material HfC anti-ablation coating according to claim 1, is characterized in that, the thickness of coating described in step (3) is 50 μ m～1500 μ m; The temperature of the oven is 100°C to 200°C. 7. The preparation method of the carbon/carbon composite material HfC anti-ablation coating according to claim 1, characterized in that, the inert gas described in step (4) is argon with a mass purity of not less than 99.9%.

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