CN103058711A - Method for preparing UHTC (Ultra-High Temperature Ceramic) matrix composite material through modification of UHTC powder basal body - Google Patents

Abstract

The invention relates to a method for preparing super high temperature ceramic matrix composite material through modification of super high temperature ceramic powder matrix. The invention adopts vacuum pressure impregnation method to introduce ultra-high temperature ceramic (UHTC) powder and carbon organic precursor into 30%vol-40vol% porosity C/SiC, combined with reactive melt infiltration (RMI) to make molten silicon and matrix The cracked carbon reacts in situ to generate SiC and densifies the material to prepare C/SiC-UHTC composites. 30vol%-40vol% porosity C/SiC is used as the preform. On the one hand, the SiC matrix protects the fiber from molten silicon erosion during the RMI process to improve the mechanical properties of the material. On the other hand, a certain amount of UHTC can be introduced into the preform. Powder improves anti-ablation performance.

Description

A method for preparing ultra-high temperature ceramic matrix composite materials by modifying ultra-high temperature ceramic powder matrix

technical field

The invention relates to a preparation method of an ultra-high temperature ceramic matrix composite material, in particular to a method for modifying the matrix of the ablation resistance performance of a C/SiC ceramic matrix composite material by means of ultra-high temperature ceramic powder (UHTC).

Background technique

Continuous carbon fiber toughened silicon carbide ceramic matrix composite (C/SiC) is an ideal high-temperature structural material, which has a series of advantages such as high temperature resistance, low density, high strength, and thermal shock resistance. Aircraft thermal protection systems and rocket engine nozzles have a wide range of applications and prospects. Since the SiC matrix is passively oxidized below 1700°C, a SiO ₂ layer protection material is formed on the surface of the material; the C/SiC structural composite material can be used for a long time at a temperature below 1700°C. Atmospheric re-entry vehicle nose cone, wing leading edge and rocket engine nozzle and other hot-end parts have a temperature exceeding 1800 °C. In this temperature environment, C/SiC actively oxidizes and loses the surface SiO ₂ protective layer, resulting in serious damage to the fiber and matrix. Ablation, a sharp decline in anti-ablation and oxidation resistance can easily lead to component failure.

Borides and carbides of transition metal elements (MB ₂ , MC; M=Hf, Zr, Ta...) have ultra-high melting points exceeding 3000°C, and are called ultra-high temperature ceramics (UHTC). Ultrahigh-temperature ceramics have a series of advantages such as high melting point, high hardness, and high-temperature strength, and are considered as candidate materials for extreme thermal and chemical environments. Due to the brittleness of ceramics, UHTC cannot be used alone as a material for large structural parts. Continuous fiber toughened ceramic matrix composites can overcome the brittleness of ceramics; adding ultra-high temperature ceramic powder to C/SiC composites overcomes the brittleness of bulk ceramics on the one hand, and improves the ablation resistance of the material on the other hand. Therefore, ultra-high temperature ceramic (UHTC) powder modified C/SiC composite materials can obtain the comprehensive advantages of high-temperature ablation performance and mechanical properties of materials, and become an effective method to improve the high-temperature ablation resistance of C/SiC.

Zirconium boride ZrB ₂ in ultra-high temperature ceramics has a high melting point (3040°C), low density (6.09g/cm ³ ), good chemical stability, and high thermal conductivity, and has gradually become the focus of research; in addition, its oxide ZrO ₂ With a melting point of 3010°C, it has the potential to be more superior in terms of ablation resistance. The preparation of C/SiC-ZrB ₂ composites generally directly introduces ZrB ₂ particles into C/SiC, the literature "Yiguang Wang, Wen Liu, Laifei cheng, Litong Zhang et al. Preparation and properties of 2D C/SiC ultra high temperature ceramiccomposites[J ]Material Science and Engineering A524 (2009) 129-133 ", the two-dimensional carbon fiber cloth coated with ZrB ₂ particle polycarbosilane (PCS) slurry was stacked and solidified after cracking and chemical vapor deposition (CVI) SiC matrix was prepared to prepare 2D C/SiC- _ZrB2 composites. The document "Z.Wang, SMDong, et al.Mechanical properties and microstructures of CvSiC-ZrC composites using T700SC carbon fibers as reinforcements" stacked two-dimensional carbon fiber cloth coated with ZrC particle polycarbosilane (PCS) slurry under a certain pressure after curing and cracking Prepared Cf/SiC-ZrC. The material prepared by this method has high content of ZrB ₂ and ZrC, but poor interlayer bonding leads to greatly reduced mechanical properties and ablation properties. Wang Yiguang, Zhu Xiaojuan et al prepared C/C-ZrC composites by reacting metal Zr and C/C composite matrix C by reactive melt infiltration (RMI) (Journal of Material Science and Engineering A524(2009)129-133), The ablation resistance of the material is improved to a certain extent. Since the RMI process uses C/C as the preform, the mechanical properties of the material are much lower than that of C/SiC.

The invention adopts vacuum pressure impregnation method to introduce UHTC powder and carbon organic precursor into 30%vol-40vol% porosity C/SiC, combined with reactive melt infiltration (RMI) to make the molten silicon and the cracked carbon in the matrix react in situ Generate SiC and densify the material to prepare C/SiC-UHTC composites. 30vol%-40vol% porosity C/SiC is used as the preform. On the one hand, the SiC matrix protects the fiber from molten silicon erosion during the RMI process to improve the mechanical properties of the material. On the other hand, a certain amount of UHTC can be introduced into the preform. Powder improves anti-ablation performance.

Contents of the invention

In order to overcome the problems of poor mechanical properties and ablation properties of materials in the prior art due to weak matrix bonding caused by slurry coating and fiber erosion caused by RMI. The invention provides a novel preparation method of C/SiC-UHTC composite material.

The technical solution adopted by the present invention to solve its technical problems comprises the following steps:

Step 1: Clean the C/SiC composite material preform with an open porosity of 30vol%-40vol% by ultrasonic cleaning for at least 30 minutes, and dry it in an oven at 120°C-150°C;

Step 2: Add UHTC powder to cellulose sodium CMC aqueous solution with a mass fraction of 0.5%-1% and ball mill for more than 24 to 48 hours to prepare slurry A; mix the carbon organic precursor and hexamethylenetetramine according to the mass ratio 10:1 was dissolved in absolute ethanol to prepare slurry B; adjust the content of absolute ethanol or aqueous solution to control the viscosity of the slurry at 40-80mPa·s, and adjust the pH value to be greater than 11 to control the dispersion of the slurry;

Step 3: Vacuum-impregnate the C/SiC preform obtained in Step 1 with the slurry A for about 30 minutes, then pressurize the inert gas to 0.8MPa to impregnate the slurry A for 1 minute and dry, repeat the impregnation and drying 3-4 times; finally Impregnate slurry B to introduce a certain amount of UHTC powder and carbon organic precursor into the C/SiC preform

Step 4: Solidification and cracking: heat the material prepared in step 3 at 80°C and 150°C for 2 hours in an oven, and then heat-treat at 900°C-1800°C for 2 hours under the protection of argon to obtain C/SiC-UHTC-C;

Step 5: The C/SiC-UHTC-C prepared in step 4 is melted and siliconized in a high-temperature vacuum furnace by the reaction melt infiltration method to prepare a C/SiC-UHTC composite material, wherein the siliconizing temperature is 1420°C-1700°C, The siliconizing time is 1-3h.

The raw materials used for slurry impregnation are ultra-high temperature ceramics, such as ZrB ₂ , ZrC, HfC, and HfB ₂ powders.

The particle size of the powder is less than 2um.

The carbon organic precursor is a carbon organic precursor, such as phenolic resin, furan resin, silane resin.

The beneficial effect of the present invention is: the present invention adopts the vacuum pressure impregnation method to introduce UHTC powder and carbon organic precursor into C/SiC, and combines the reaction melt infiltration method to generate SiC in situ by the reaction of elemental silicon and cracked C in the matrix to obtain The material is dense and has good mechanical properties. In addition, the SiC generated by RMI effectively wraps UHTC, and its distribution is uniform, which effectively improves the anti-ablation performance. C/SiC with a porosity of 30vol%-40vol% is used as the prefabricated body, which effectively protects the carbon fiber and ensures the mechanical properties of the composite material.

The present invention will be further described below in conjunction with accompanying drawings and examples.

Description of drawings

Fig. 1 is the C/SiC- _ZrB prepared by the present invention Polished section backscattering picture

Fig. 2 is the SEM picture of the three-point bending section of the C/SiC- _ZrB composite material prepared by the present invention

Detailed ways

Example 1

Step 1: Composite material preform preparation: The C/SiC composite material preform with an open porosity of 30vol%-40vol% is ultrasonically cleaned for at least 30 minutes, and dried in an oven at 80°C-100°C for later use.

Step 2: Slurry preparation: Add ZrB ₂ powder to 0.5%-1% mass fraction of cellulose sodium (CMC) aqueous solution and ball mill for more than 24 hours to prepare slurry A. Slurry B was prepared by dissolving phenolic resin and hexamethylenetetramine in absolute alcohol at a mass ratio of 10:1. The viscosity of the above-mentioned slurry is controlled by the content of absolute alcohol or aqueous solution to about 60mPa·s, and the dispersibility is controlled by adjusting the pH value (greater than 11).

Step 3: Vacuum pressure impregnation: The C/SiC preform in step 1 is vacuum-impregnated with slurry A for about 30 minutes, then pressurized to 0.8MPa with an inert gas to pressure-impregnate slurry A for about 30 minutes and dried, and then repeatedly impregnated and dried 3-4 times, a sufficient amount of ZrB ₂ is introduced into the C/SiC preform; finally, the slurry B is vacuum impregnated for about 30 minutes, thereby introducing a certain amount of phenolic resin into the C/SiC preform.

Step 4: curing and cracking: heat the material prepared in step 3 in an oven at 80°C and 150°C for 2 hours, and then heat-treat at 900°C-1800°C for 2 hours under the protection of argon to obtain C/SiC-ZrB ₂ -C.

Step 5: Reaction Melt Infiltration (RMI): The C/SiC-ZrB ₂ -C prepared in Step 4 was melted and siliconized in a high-temperature vacuum furnace by the reaction melt infiltration method to prepare a C/SiC-ZrB ₂ composite material, wherein The siliconizing temperature is 1420°C-1700°C, and the siliconizing time is 1-3h.

Example 2

Step 1: Composite material preform preparation: The C/SiC composite material preform with an open porosity of 30vol%-40vol% is ultrasonically cleaned for at least 30 minutes, and dried in an oven at 80°C-100°C for later use.

Step 2: Slurry preparation: Add ZrC powder to cellulose sodium (CMC) aqueous solution with a mass fraction of 0.5%-1% and ball mill for more than 24 hours to prepare slurry A. Prepare slurry B by dissolving polycarbosilane (PCS) in absolute alcohol. The viscosity of the above-mentioned slurry is controlled by the content of absolute alcohol or aqueous solution to about 60mPa·s, and the dispersibility is controlled by adjusting the pH value (greater than 11).

Step 3: Vacuum pressure impregnation: The C/SiC preform in step 1 is vacuum-impregnated with slurry A for about 30 minutes, then pressurized to 0.8MPa with an inert gas to pressure-impregnate slurry A for about 30 minutes and dried, and then repeatedly impregnated and dried 3-4 times, a sufficient amount of ZrC is introduced into the C/SiC preform; finally, the slurry B is vacuum impregnated for about 30 minutes, thereby introducing a certain amount of PCS to impregnate the C/SiC preform.

Step 4: Solidification and cracking: heat the material prepared in step 3 at 80°C and 150°C for 2 hours in an oven, and then heat-treat at 900°C-1800°C for 2 hours under the protection of argon to obtain C/SiC-ZrC-C.

Step 5: Reaction Melt Infiltration (RMI): Reaction Melt Infiltration (RMI): The C/SiC-ZrC-C prepared in Step 4 is melted and siliconized in a high-temperature vacuum furnace by the reaction melt infiltration method to prepare C/SiC -ZrC composite material, wherein the siliconizing temperature is 1420°C-1700°C, and the siliconizing time is 1-3h.

Claims (4)

1. method for preparing ultra-temperature ceramic-based composite material by superhigh temperature ceramics powder matrix modification is characterized in that step is as follows:

Step 1: be that the C/SiC composite preform of 30vol%-40vol% is with ultrasonic cleaning at least 30 minutes, 120 ℃ of-150 ℃ of oven dry in the baking oven with the ventilate rate;

Step 2: the UHTC powder joined ball milling prepares slurry A in the sodium cellulosate CMC aqueous solution that massfraction is 0.5%-1% more than 24 ~ 48 hours; With carbon organic precursor and hexamethylenetetramine in mass ratio 10:1 be dissolved in and prepare slurry B in the dehydrated alcohol; The viscosity of the content control slurry of adjustment dehydrated alcohol or the aqueous solution is regulated pH value greater than 11 dispersivenesses with the control slurry at 40-80mPas;

Then step 3: the vacuum impregnation slurry A of C/SiC precast body elder generation that step 1 is obtained approximately 30 minutes is pressurized to 0.8MPa dipping sizing agent A minute and dry by rare gas element, repeated impregnations and dry 3-4 time; Final impregnating slurry B, thus a certain amount of UHTC powder and carbon organic precursor introduced in the C/SiC precast body

Step 4: solidify cracking: the material of step 3 preparation is incubated 2 hours at 80 ℃, 150 ℃ successively in baking oven, then lower 900 ℃ of-1800 ℃ of thermal treatments of argon shield obtained C/SiC-UHTC-C in 2 hours;

Step 5: the C/SiC-UHTC-C of step 4 preparation is prepared the C/SiC-UHTC matrix material by the melting siliconising in vacuum high temperature furnace of reactive melt infiltration method, and wherein siliconising temperature is 1420 ℃-1700 ℃, and the siliconising time is 1-3h.

2. the described method for preparing ultra-temperature ceramic-based composite material by superhigh temperature ceramics powder matrix modification according to claim 1, it is characterized in that: the slurry dipping raw material that uses is superhigh temperature ceramics, such as ZrB ₂, ZrC, HfC, HfB ₂Powder.

3. the described method for preparing ultra-temperature ceramic-based composite material by superhigh temperature ceramics powder matrix modification according to claim 2, it is characterized in that: described powder diameter is less than 2um.

4. the described method for preparing ultra-temperature ceramic-based composite material by superhigh temperature ceramics powder matrix modification according to claim 1, it is characterized in that: described carbon organic precursor is the carbon organic precursor, such as resol, furane resin, silane resin.

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