Three-dimensional carbon fiber toughened low-expansion ceramic matrix composite material and preparation method thereof

Abstract

The invention relates to a three-dimensional carbon fiber toughened low-expansion ceramic-based composite material and a preparation method thereof, and belongs to the field of ceramic-based composite materials. Comprising the following steps: weaving carbon fibers into a continuous carbon fiber preform, soaking in acetone, cleaning with distilled water, and drying in a drying oven; uniformly mixing the low-expansion ceramic powder and a dispersing agent in deionized water to obtain ceramic slurry; dipping the pretreated continuous carbon fiber preform into the low-expansion ceramic slurry, carrying out ultrasonic treatment under a vacuum condition, controlling the ultrasonic power and time, and carrying out vacuum drying to obtain a carbon fiber toughened low-expansion ceramic green body; and putting the green body into a graphite mold, and carrying out hot pressing sintering in a vacuum hot pressing furnace to obtain the continuous carbon fiber toughened low-expansion ceramic matrix composite material. The process is simple, the forming time is short, the cost is low, the fracture toughness of the low-expansion ceramic material is remarkably improved, meanwhile, the low thermal expansion coefficient and the low thermal conductivity are kept, and the high application value is achieved in the fields of precise instruments, aerospace, military high-temperature missiles, waste fixing and the like.

Description

Technical Field

[0001] The invention belongs to the field of ceramic-based composite materials, and particularly relates to a three-dimensional carbon fiber toughened low-expansion ceramic-based composite material and a preparation method thereof. Background Art

[0002] Thermal expansion and contraction are inherent properties of objects. The dimensional fluctuation and thermal mismatch caused by temperature changes have become the main obstacles restricting the development of aerospace, electronic thermal control, precision instruments and other fields. Therefore, the development of thermally stable materials with low expansion coefficients and comprehensive performance has become the key to breaking through the above bottlenecks and promoting the development of related fields.

[0003] Sodium zirconium phosphate (NaZr2(PO3)4) is referred to as NZP, in which a variety of different ion substitutions can occur at the cation position to form a series of derivatives with the same structure, collectively referred to as NZP family compounds. NZP family phosphate ceramics made from this compound as powder have low or negative thermal expansion coefficient, low thermal conductivity, good thermal shock resistance and thermal stability. Therefore, NZP family phosphate ceramics have important application and research value in occasions that need to withstand temperature changes without significant dimensional changes, such as aerospace, precision instruments, high-temperature missiles in the military field, etc. However, the mechanical properties of NZP family phosphate ceramics are relatively poor, with high brittleness and low toughness, and the fracture toughness is less than 2MPa·m 1 / 2 , which seriously limits its application. Researchers have improved the mechanical properties of NZP phosphate ceramics by introducing reinforcing phases and adding sintering aids, but the effect is not prominent enough. In addition, the introduced second phase is usually a high expansion phase, which will destroy the low thermal expansion characteristics of NZP ceramics. Therefore, improving the toughness of NZP phosphate ceramic materials while maintaining low thermal expansion and low thermal conductivity is still a research hotspot today.

[0004] Carbon fiber has the advantages of low density, low thermal conductivity, high strength, high specific modulus, and low thermal expansion coefficient. When the fiber is added to the ceramic matrix, the toughness of the ceramic material can be significantly improved. Carbon fiber mainly includes chopped carbon fiber, two-dimensional carbon fiber cloth and three-dimensional carbon fiber preform. Among them, the three-dimensional carbon fiber preform prepared by winding, weaving, acupuncture, etc. has excellent mechanical properties in the plane and between layers, which can greatly improve the fracture toughness and fracture work of ceramic materials. It is currently the most effective toughening phase. However, research on the toughening of low-expansion phosphate ceramic materials with three-dimensional carbon fiber preforms has not been reported.

[0005] In view of the above-mentioned defects, the inventors of the present invention proposed the present invention after a long period of research and practice. Summary of the invention

[0006] In view of the shortcomings of the prior art, the present invention discloses a three-dimensional carbon fiber toughened low expansion ceramic matrix composite material and a preparation method thereof. The three-dimensional carbon fiber toughened low expansion ceramic matrix composite material of the present invention has excellent mechanical properties, and has both low thermal expansion coefficient and low thermal conductivity, and has good application prospects.

[0007] Furthermore, the preparation method of the three-dimensional carbon fiber toughened low expansion ceramic matrix composite material comprises the following steps:

[0008] Step 1: Soak the continuous carbon fiber preform in acetone, wash it with distilled water for 3-5 times, and then dry it in an oven;

[0009] Step 2: Weigh low expansion phosphate ceramic powder, add dispersant, and perform ball milling with deionized water as the medium to obtain a uniformly dispersed low expansion ceramic slurry;

[0010] Step 3: impregnate the pretreated continuous carbon fiber preform into the low expansion ceramic slurry, perform ultrasonic impregnation treatment under vacuum conditions, dry to constant weight after impregnation, repeat the impregnation cycle 2-5 times until the weight no longer increases, and obtain a carbon fiber toughened low expansion ceramic green body;

[0011] Step 4: Place the carbon fiber reinforced low expansion ceramic green body into a hot pressing sintering furnace, and sinter it under the protection of vacuum or argon inert atmosphere to obtain a continuous carbon fiber reinforced low expansion ceramic matrix composite material.

[0012] Furthermore, the continuous carbon fiber preform in the first step is a kind of a needle-punched carbon fiber preform, a 2.5D carbon fiber preform, or a fine-woven puncture carbon fiber preform, and the fiber volume fraction of the fiber preform is 20-55%.

[0013] Furthermore, the low expansion phosphate ceramic powder in the second step is one or more of NZP family compounds, and has a particle size of 50nm-5μm.

[0014] Furthermore, the dispersant in the second step is selected from at least one of polyethylene glycol, tetramethylammonium hydroxide, sodium tripolyphosphate, sodium carboxymethyl cellulose, polymethacrylate and sodium polyacrylate, and the mass of the dispersant is 0.2-5wt% of the mass of the ceramic powder.

[0015] Furthermore, the volume fraction of the ceramic slurry in the second step is 15-55%.

[0016] Furthermore, in the second step, the ball mill speed is 100-300 r / min, and the ball milling time is 30 min-6 h.

[0017] Furthermore, in the third step, under the condition that the vacuum degree is 1Pa-10Pa, the ultrasonic frequency is 20-130kHZ, and the time is 20min-2h.

[0018] Furthermore, in the fourth step, the hot pressing sintering temperature is 1000-1400° C., the sintering time is 5-120 min, the heating rate is 10-200° C. / min, the cooling rate is 10-150° C. / min, and the pressure is 5-50 MPa.

[0019] Beneficial effects of the present invention:

[0020] The three-dimensional carbon fiber toughened low expansion ceramic matrix composite material and the preparation method thereof provided by the present invention have the following advantages compared with the prior art:

[0021] 1. The three-point bending strength of the three-dimensional carbon fiber toughened low expansion ceramic matrix composite material prepared by the present invention is 72MPa, and the fracture toughness is 4.8MPa·m 1 / 2 The average thermal expansion coefficient is 1.3×10 -6 / ℃(100-600℃), thermal conductivity is 0.66W m -1 / ℃(600℃).

[0022] 2. Compared with phosphate ceramic materials, the fracture toughness of the three-dimensional carbon fiber-reinforced low-expansion ceramic-based composite material prepared by the present invention is greatly improved, and it has a lower thermal expansion coefficient and thermal conductivity, achieving the coordinated optimization of the comprehensive performance of the material including mechanical properties, thermal expansion properties, and thermal conductivity.

[0023] 3. The process of the present invention is simple, the preparation process cycle is short, the cost is low, it is suitable for large-scale production, and has great application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is the XRD spectrum of the three-dimensional carbon fiber toughened low expansion ceramic matrix composite material prepared in Example 1.

[0025] Figure 2 This is the SEM image of the three-dimensional carbon fiber toughened low expansion ceramic matrix composite material prepared in Example 1.

[0026] Figure 3 This is the thermal expansion curve of the three-dimensional carbon fiber toughened low expansion ceramic matrix composite material prepared in Example 1.

[0027] Figure 4 The thermal conductivity of the three-dimensional carbon fiber toughened low expansion ceramic matrix composite material prepared in Example 1.

[0028] Figure 5 This is a SEM image of the three-dimensional carbon fiber toughened low expansion ceramic matrix composite material prepared in Example 2. DETAILED DESCRIPTION

[0029] The technical scheme of the embodiment of the present invention will be more clearly explained below in conjunction with the drawings in the embodiment of the present invention. The following description is only a preferred embodiment of the present invention, but is not limited to the following embodiment and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

[0030] Example 1

[0031] A three-dimensional carbon fiber toughened low expansion ceramic matrix composite material and a preparation method thereof, comprising the following steps:

[0032] A fine-woven puncture structure carbon fiber preform with a fiber content of 25% was soaked in acetone, washed with distilled water for 3 times, and then dried in an oven.

[0033] Weigh low-expansion CaZr4(PO4)6 ceramic powder, add 0.5wt% polyethylene glycol, and ball-mill with deionized water as the medium. The volume fraction of the ceramic slurry is 35%, the ball mill speed is 200r / min, and the ball milling time is 4h to obtain a uniformly dispersed low-expansion ceramic slurry.

[0034] The pretreated fine-woven puncture structure carbon fiber preform is impregnated into a low-expansion ceramic slurry, and ultrasonic impregnation treatment is performed under vacuum conditions. Under the condition of a vacuum degree of 10 Pa, an ultrasonic frequency of 100 kHz, and a time of 30 min, and after impregnation, it is dried to a constant weight, and the impregnation cycle is repeated 3 times until the weight no longer increases, thereby obtaining a carbon fiber-reinforced low-expansion ceramic green body;

[0035] The carbon fiber toughened low expansion ceramic green body is placed in a hot pressing sintering furnace and sintered under vacuum atmosphere protection. The hot pressing sintering temperature is 1200°C, the sintering time is 15min, the heating rate is 100°C / min, the cooling rate is 100°C / min, and the pressure is 40MPa to obtain the continuous carbon fiber toughened low expansion ceramic matrix composite material. The XRD spectrum of the continuous carbon fiber toughened low expansion ceramic matrix composite material obtained in Example 1 is as follows Figure 1 As shown; SEM pictures as Figure 2 As shown; the flexural strength is 72MPa and the fracture toughness is 4.8MPa·m 1 / 2 ; Thermal expansion curves such as Figure 3 As shown, the average thermal expansion coefficient is 1.3×10 -6 / ℃(100-600℃); thermal conductivity Figure 4 As shown, the thermal conductivity is 0.66 W m at 600 °C. -1 / ℃.

[0036] Example 2

[0037] A three-dimensional carbon fiber toughened low expansion ceramic matrix composite material and a preparation method thereof, comprising the following steps:

[0038] A fine-woven puncture structure carbon fiber preform with a fiber content of 35% was soaked in acetone, washed with distilled water for 3 times, and then dried in an oven.

[0039] Weigh low-expansion CaZr4(PO4)6 ceramic powder, add 1wt% sodium carboxymethyl cellulose, and ball-mill with deionized water as the medium. The volume fraction of the ceramic slurry is 30%, the ball mill speed is 250r / min, and the ball milling time is 3h to obtain a uniformly dispersed low-expansion ceramic slurry.

[0040] The pretreated fine-woven puncture structure carbon fiber preform is impregnated into a low-expansion ceramic slurry, and ultrasonic impregnation treatment is performed under vacuum conditions. Under the condition of a vacuum degree of 5 Pa, the ultrasonic frequency is 80 kHz, and the time is 1 hour. After impregnation, it is dried to a constant weight, and the impregnation cycle is repeated 4 times until the weight no longer increases, thereby obtaining a carbon fiber-reinforced low-expansion ceramic green body;

[0041] The carbon fiber toughened low expansion ceramic green body is placed in a hot pressing sintering furnace and sintered under vacuum atmosphere protection. The hot pressing sintering temperature is 1300°C, the sintering time is 10min, the heating rate is 50°C / min, the cooling rate is 50°C / min, and the pressure is 30MPa to obtain the continuous carbon fiber toughened low expansion ceramic matrix composite material. SEM picture as shown Figure 5 shown.

[0042] Example 3

[0043] A three-dimensional carbon fiber toughened low expansion ceramic matrix composite material and a preparation method thereof, comprising the following steps:

[0044] A 2.5D structural carbon fiber preform with a fiber content of 40% was soaked in acetone, washed with distilled water for 3 times, and then dried in an oven.

[0045] Weigh low-expansion NaZr4(PO4)6 ceramic powder, add 2wt% polymethacrylate, and ball-mill with deionized water as the medium. The volume fraction of the ceramic slurry is 40%, the ball mill speed is 150r / min, and the ball milling time is 5h to obtain a uniformly dispersed low-expansion ceramic slurry.

[0046] The pretreated fine-woven puncture structure carbon fiber preform is impregnated into a low-expansion ceramic slurry, and ultrasonic impregnation treatment is performed under vacuum conditions. Under the condition of a vacuum degree of 8 Pa, an ultrasonic frequency of 130 kHz, and a time of 1.5 h, and after impregnation, it is dried to a constant weight, and the impregnation cycle is repeated twice until the weight no longer increases, thereby obtaining a carbon fiber-reinforced low-expansion ceramic green body;

[0047] The carbon fiber reinforced low expansion ceramic green body is placed in a hot pressing sintering furnace and sintered under vacuum atmosphere protection. The hot pressing sintering temperature is 1100°C, the sintering time is 1h, the heating rate is 20°C / min, the cooling rate is 50°C / min, and the pressure is 40MPa to obtain the continuous carbon fiber reinforced low expansion ceramic matrix composite material.

Claims

1. A three-dimensional carbon fiber toughened low expansion ceramic matrix composite material and a preparation method thereof, characterized in that: The preparation method comprises the following steps: Step 1: Soak the continuous carbon fiber preform in acetone, wash it with distilled water for 3-5 times, and then dry it in an oven; Step 2: Weigh low expansion phosphate ceramic powder, add dispersant, and perform ball milling with deionized water as the medium to obtain a uniformly dispersed low expansion ceramic slurry; Step 3: impregnate the pretreated continuous carbon fiber preform into the low expansion ceramic slurry, perform ultrasonic impregnation treatment under vacuum conditions, dry to constant weight after impregnation, repeat the impregnation cycle 2-5 times until the weight no longer increases, and obtain a carbon fiber toughened low expansion ceramic green body; Step 4: Place the carbon fiber reinforced low expansion ceramic green body into a hot pressing sintering furnace, and sinter it under the protection of vacuum or argon inert atmosphere to obtain a continuous carbon fiber reinforced low expansion ceramic matrix composite material.

2. A three-dimensional carbon fiber toughened low expansion ceramic matrix composite material and a preparation method thereof according to claim 1, characterized in that: In the first step, the continuous carbon fiber preform is a kind of needle-punched carbon fiber preform, 2.5D carbon fiber preform, or fine-woven puncture carbon fiber preform, and the fiber volume fraction of the fiber preform is 20-55%.

3. A three-dimensional carbon fiber toughened low expansion ceramic matrix composite material and a preparation method thereof according to claim 1, characterized in that: In the second step, the low expansion phosphate ceramic powder is one or more of NZP family compounds, and the particle size is 50nm-5μm.

4. A three-dimensional carbon fiber toughened low expansion ceramic matrix composite material and a preparation method thereof according to claim 1, characterized in that: The dispersant in the second step is selected from at least one of polyethylene glycol, tetramethylammonium hydroxide, sodium tripolyphosphate, sodium carboxymethyl cellulose, polymethacrylate and sodium polyacrylate, and the mass of the dispersant is 0.2-5wt% of the mass of the ceramic powder.

5. A three-dimensional carbon fiber toughened low expansion ceramic matrix composite material and a preparation method thereof according to claim 1, characterized in that: In the second step, the volume fraction of the ceramic slurry is 15-55%.

6. A three-dimensional carbon fiber toughened low expansion ceramic matrix composite material and a preparation method thereof according to claim 1, characterized in that: In the second step, the ball mill speed is 100-300 r / min, and the ball milling time is 30 min-6 h.

7. A three-dimensional carbon fiber toughened low expansion ceramic matrix composite material and a preparation method thereof according to claim 1, characterized in that: In the third step, under the condition of vacuum degree of 1Pa-10Pa, ultrasonic frequency is 20-130kHZ, and the time is 20min-2h.

8. The three-dimensional carbon fiber toughened low expansion ceramic matrix composite material and the preparation method thereof according to claim 1, characterized in that: In the fourth step, the hot pressing sintering temperature is 1000-1400° C., the sintering time is 5-120 min, the heating rate is 10-200° C. / min, the cooling rate is 10-150° C. / min, and the pressure is 5-50 MPa.

9. A three-dimensional carbon fiber toughened low expansion ceramic matrix composite material and a preparation method thereof, characterized in that: The composite material is prepared by the method for preparing a three-dimensional carbon fiber toughened low expansion ceramic matrix composite material as described in any one of claims 1 to 8.

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