阅读说明：本技术 一种热防护连接用复合陶瓷材料的制备方法 (Preparation method of composite ceramic material for thermal protection connection ) 是由 曾军 于 2019-09-30 设计创作，主要内容包括：本发明涉及一种热防护连接用复合陶瓷材料的制备方法,属于陶瓷材料技术领域。本发明以氮化硅为原料,制备热防护连接用复合陶瓷材料,氮化硅既有一般陶瓷材料的坚硬、耐热、耐磨、耐腐蚀的优点,又具备了抗热震好、耐高温蠕变、自润滑好、化学稳定性能佳等优势,还具有相对较低的密度以及低的介电常数、介电损耗等优良的介电性能,氮化硅中硅、氮两种元素电负性相近,具有高的蒸汽压和很低的扩散系数,由于氮化硅是键强高的共价化合物,并在空气中能形成氧化物保护膜,所以还具有良好的化学稳定性,以碳化硅为原料可以有效提高热防护连接用复合陶瓷材料的可靠性,使热防护连接用复合陶瓷材料具有良好的硬度和承载能力。(The invention relates to a preparation method of a composite ceramic material for thermal protection connection, belonging to the technical field of ceramic materials. The silicon nitride is used as a raw material to prepare the composite ceramic material for thermal protection connection, the silicon nitride has the advantages of hardness, heat resistance, wear resistance and corrosion resistance of common ceramic materials, has the advantages of good thermal shock resistance, high-temperature creep resistance, good self-lubrication, good chemical stability and the like, has relatively low density, low dielectric constant, dielectric loss and other excellent dielectric properties, has similar electronegativity of silicon and nitrogen elements in the silicon nitride, high vapor pressure and low diffusion coefficient, and has good chemical stability because the silicon nitride is a covalent compound with strong bond and can form an oxide protective film in the air, and the silicon carbide is used as the raw material to effectively improve the reliability of the composite ceramic material for thermal protection connection, so that the composite ceramic material for thermal protection connection has good hardness and bearing capacity.)

1. A preparation method of a composite ceramic material for thermal protection connection is characterized by comprising the following specific preparation steps:

(1) adding polyvinyl alcohol, sodium dodecyl benzene sulfonate and absolute ethyl alcohol into deionized water, and stirring at the rotating speed of 200-240 r/min for 10-12 min at normal temperature to obtain a mixed solution;

(2) adding silicon nitride powder, zirconium silicate powder, carbon fiber, calcium oxide powder and magnesium oxide powder into the mixed solution, placing the mixed solution into a ball mill, performing ball milling for 1-2 hours at the rotating speed of 200-250 r/min at normal temperature, and placing the ball mill into an ultrasonic dispersion machine for ultrasonic oscillation for 30-40 min to obtain mixed slurry;

(3) drying the mixed slurry in an oven at 100-120 ℃ for 2-4 h, cooling at normal temperature to obtain mixed powder, putting the mixed powder in a press, dry-pressing the powder at normal temperature to form, and maintaining the pressure for 30-40 s to obtain a biscuit;

(4) and (3) placing the biscuit in a microwave sintering furnace, heating to 600-800 ℃ from normal temperature at the heating rate of 10 ℃/min, pre-sintering for 40-60 min, then quickly heating to 1500-1600 ℃, carrying out heat preservation sintering for 1-2 h, and cooling to room temperature along with the furnace to obtain the composite ceramic material for thermal protection connection.

2. The method for preparing the composite ceramic material for thermal protection connection according to claim 1, wherein the silicon nitride powder, the zirconium silicate powder, the carbon fiber, the polyvinyl alcohol, the sodium dodecyl benzene sulfonate, the calcium oxide powder, the magnesium oxide powder, the anhydrous ethanol and the deionized water are 40-60 parts by weight of the silicon nitride powder, 20-30 parts by weight of the zirconium silicate powder, 8-12 parts by weight of the carbon fiber, 2-3 parts by weight of the polyvinyl alcohol, 0.4-0.6 part by weight of the sodium dodecyl benzene sulfonate, 0.2-0.3 part by weight of the calcium oxide powder, 0.2-0.3 part by weight of the magnesium oxide powder, 40-60 parts by weight of the anhydrous ethanol and 40-60 parts by weight of the deionized water.

3. The method for preparing a composite ceramic material for thermal protection connection according to claim 1, wherein the power of the ultrasonic oscillation in the step (2) is 400-500W.

4. The preparation method of the composite ceramic material for the thermal protection connection according to claim 1, wherein the pressure of the dry pressing in the step (3) is 240-280 MPa.

5. The method for preparing a composite ceramic material for thermal protection connection according to claim 1, wherein the temperature rise rate of the rapid temperature rise in the step (4) is 50 ℃/min.

6. The preparation method of the composite ceramic material for the thermal protection connection according to claim 1, wherein the zirconium silicate powder in the step (2) is prepared by the following specific steps:

(1) adding zirconium oxychloride into 1/2 deionized water, and stirring at the normal temperature at the rotating speed of 200-240 r/min for 12-16 min to obtain a zirconium oxychloride solution;

(2) adding tetraethoxysilane and ammonia water into the residual 1/2 deionized water, and stirring at the normal temperature at the rotating speed of 240-280 r/min for 1-2 hours to obtain sol;

(3) adding a zirconium oxychloride solution into the sol, stirring for 40-60 min at a rotating speed of 200-240 r/min under a water bath condition of 40-60 ℃, and standing for 1-2 h to obtain a gel;

(4) and placing the gel in a reaction kettle, performing hydrothermal reaction for 10-12 h at 120-140 ℃, performing vacuum filtration, taking a filter cake, washing the filter cake for 3-5 times by using deionized water, placing the filter cake in an oven at 60-80 ℃ for drying for 2-4 h, and grinding to obtain zirconium silicate powder.

7. The preparation method of the composite ceramic material for the thermal protection connection according to claim 6, wherein the weight parts of the zirconium oxychloride, the tetraethoxysilane, the ammonia water and the deionized water are 40-50 parts of the zirconium oxychloride, 48-60 parts of the tetraethoxysilane, 16-20 parts of the 1% ammonia water by mass concentration and 240-300 parts of the deionized water.

8. The method for preparing the composite ceramic material for the thermal protection connection according to claim 1, wherein the silicon nitride powder in the step (2) is prepared by the following specific steps:

(1) placing silicon dioxide powder and carbon powder in a stirrer, and stirring at the normal temperature at a rotating speed of 180-200 r/min for 20-30 min to obtain mixed powder;

(2) placing the mixed powder in a tubular atmosphere furnace, introducing nitrogen, heating to 1500-1600 ℃ from normal temperature under the power of 8-10 kW, carrying out heat preservation calcination for 1-2 h, and cooling to room temperature along with the furnace to obtain reaction powder;

(3) and (3) placing the reaction powder in a muffle furnace, heating to 600-800 ℃ from normal temperature at the heating rate of 5 ℃/min, carrying out heat preservation calcination for 40-60 min, and cooling to room temperature along with the furnace to obtain silicon nitride powder.

9. The preparation method of the composite ceramic material for the thermal protection connection as claimed in claim 8, wherein the weight parts of the silicon dioxide powder and the carbon powder are 30-40 parts of silicon dioxide powder and 60-80 parts of carbon powder.

10. The preparation method of the composite ceramic material for the thermal protection connection as claimed in claim 8, wherein the nitrogen gas is introduced at a rate of 100 to 120mL/min in the step (2).

Technical Field

The invention relates to a preparation method of a composite ceramic material for thermal protection connection, belonging to the technical field of ceramic materials.

Background

The reuse of the spacecraft can effectively reduce the transportation cost of the space shuttle system and improve the operation efficiency, and the use in the aerospace field is bound to be increased in the future. During the process of repeatedly using the spacecraft to go and return to the space and the earth, the spacecraft needs to pass through the atmosphere at an extremely high speed, and during the passing process, the surface of the spacecraft and the surrounding atmosphere generate strong friction to generate a large amount of heat, and the surface temperature can reach thousands of degrees centigrade. The spacecraft surface is therefore equipped with a Thermal Protection System (TPS) that reduces the entry of aerodynamic heat into the interior of the body, in order to protect the internal systems that cannot withstand high temperatures from working properly. At present, the interconnection between a thermal protection system and a body structure of a spacecraft is usually realized by a connecting structure, and the connecting structure mainly plays a role in fixing and transferring load.

The thermal protection system has complex bearing condition in a service environment, bears and transmits certain total body load besides local pneumatic load, such as heat load caused by the change of the external temperature of the thermal protection system; the force load due to the load transfer. This complex load-bearing situation makes the connection area of the thermal protection system a vulnerable area, so that the connection needs to have a high load-bearing capacity. At present, a thermal protection system and a force bearing structure of a spacecraft are usually connected by using a metal connecting piece, and because a thermal insulation layer does not exist at the connecting part, the heat conducting capacity of the metal connecting piece is high, heat is transmitted from the thermal insulation layer to the force bearing structure in the thermal insulation layer too fast at the connecting part, and the problem of thermal short circuit is caused. The thermal short circuit problem can cause extreme temperatures to occur prematurely or excessively at the parts of the structures, components, etc. protected by the thermal protection system, reducing the reliability of the thermal protection system. Therefore, high requirements are also placed on the thermal conductivity of the connecting piece. Therefore, it is very important to design and prepare a connecting piece with larger bearing capacity and lower heat-conducting performance.

The bolt connection is a connection mode generally adopted by an aerospace thermal protection structural part, and a bolt fastener of the thermal protection structure can be divided into a high-temperature metal bolt and a non-metal bolt according to materials.

Due to good toughness, mechanical property and high strength, the metal material is widely applied to bearing structures and members in a normal temperature environment and is already applied to a metal thermal protection system. However, as the service temperature of the aircraft increases, the existing metal thermal protection systems have been gradually replaced with new ceramic-based thermal protection systems that can withstand higher temperatures. The self thermal conductivity of the traditional metal thermal protection connecting piece is generally large, and is not matched with the thermal expansion coefficient of a novel ceramic-based thermal protection system material, so that the problems of thermal short circuit, damage to a thermal protection system and the like are easily caused, and the development of the novel ceramic-based thermal protection connecting piece material is urgently needed.

The ceramic material, as one of non-metallic materials, has the advantages of high strength, high hardness, high temperature resistance and oxidation resistance. In the application of the composite material in the field of high-temperature heat insulation, the performance of the ceramic material is often better than that of a metal material, and the linear expansion coefficient of the ceramic is small, namely when the temperature changes, the size change of the ceramic material is small. Most ceramic materials are oxide ceramics, and the oxide has stable performance and is not easy to react with other substances at high temperature, namely, the high-temperature chemical stability is good. In summary, ceramic materials should be an ideal material for thermal protection connectors, but conventional ceramic materials have limited their wide use in the field of thermal protection connectors due to their inherent brittleness and poor processability. However, with the rapid development of materials science, the appearance of novel ceramic matrix composite materials, such as C/C and C/SiC composite materials, changes the weak position of the traditional ceramic materials in the field of thermal protection connecting pieces.

The carbon fiber toughened silicon carbide ceramic matrix composite (C/SiC) has low density, high specific strength, good high temperature resistance and corrosion resistance and good high temperature oxidation resistance, and can adapt to ultrahigh temperature service environment, thereby being an ideal thermal protection connecting piece material. However, the C/SiC composite material has the disadvantages of high manufacturing cost, low temperature oxidation resistance and difficult processing, and the application of the C/SiC composite material as a thermal protection connecting piece material is limited.

The C/C composite material is a composite material which is researched more at present and is applied to the ultrahigh-temperature field, and has excellent performance: low density, high specific modulus and specific strength, high temperature and thermal shock resistance, etc. However, the C/C composite material bolt has poor high-temperature oxidation resistance due to the material, so that the application of the C/C composite material bolt in the high-temperature field is limited.

Traditional high-temperature ceramic materials are obvious in brittleness, poor in bearing capacity and poor in reliability when used for high-temperature connection, and therefore a novel ceramic-based thermal protection connecting piece needs to be developed.

Disclosure of Invention

The technical problems to be solved by the invention are as follows: aiming at the problems of obvious brittleness and poor reliability when the traditional ceramic material is used for high-temperature connection, the preparation method of the composite ceramic material for thermal protection connection is provided.

In order to solve the technical problems, the invention adopts the technical scheme that:

(1) adding polyvinyl alcohol, sodium dodecyl benzene sulfonate and absolute ethyl alcohol into deionized water, and stirring at the rotating speed of 200-240 r/min for 10-12 min at normal temperature to obtain a mixed solution;

(2) adding silicon nitride powder, zirconium silicate powder, carbon fiber, calcium oxide powder and magnesium oxide powder into the mixed solution, placing the mixed solution into a ball mill, performing ball milling for 1-2 hours at the rotating speed of 200-250 r/min at normal temperature, and placing the ball mill into an ultrasonic dispersion machine for ultrasonic oscillation for 30-40 min to obtain mixed slurry;

(3) drying the mixed slurry in an oven at 100-120 ℃ for 2-4 h, cooling at normal temperature to obtain mixed powder, putting the mixed powder in a press, dry-pressing the powder at normal temperature to form, and maintaining the pressure for 30-40 s to obtain a biscuit;

(4) and (3) placing the biscuit in a microwave sintering furnace, heating to 600-800 ℃ from normal temperature at the heating rate of 10 ℃/min, pre-sintering for 40-60 min, then quickly heating to 1500-1600 ℃, carrying out heat preservation sintering for 1-2 h, and cooling to room temperature along with the furnace to obtain the composite ceramic material for thermal protection connection.

The silicon nitride powder, the zirconium silicate powder, the carbon fibers, the polyvinyl alcohol, the sodium dodecyl benzene sulfonate, the calcium oxide powder, the magnesium oxide powder and the absolute ethyl alcohol are 40-60 parts by weight of the silicon nitride powder, 20-30 parts by weight of the zirconium silicate powder, 8-12 parts by weight of the carbon fibers, 2-3 parts by weight of the polyvinyl alcohol, 0.4-0.6 part by weight of the sodium dodecyl benzene sulfonate, 0.2-0.3 part by weight of the calcium oxide powder, 0.2-0.3 part by weight of the magnesium oxide powder, 40-60 parts by weight of the absolute ethyl alcohol and 40-60 parts by weight of the deionized water.

And (3) the power of the ultrasonic oscillation in the step (2) is 400-500W.

And (3) the pressure of the dry pressing in the step (3) is 240-280 MPa.

The temperature rise rate of the rapid temperature rise in the step (4) is 50 ℃/min.

The specific preparation steps of the zirconium silicate powder in the step (2) are as follows:

(1) adding zirconium oxychloride into 1/2 deionized water, and stirring at the normal temperature at the rotating speed of 200-240 r/min for 12-16 min to obtain a zirconium oxychloride solution;

(2) adding tetraethoxysilane and ammonia water into the residual 1/2 deionized water, and stirring at the normal temperature at the rotating speed of 240-280 r/min for 1-2 hours to obtain sol;

(3) adding a zirconium oxychloride solution into the sol, stirring for 40-60 min at a rotating speed of 200-240 r/min under a water bath condition of 40-60 ℃, and standing for 1-2 h to obtain a gel;

(4) and placing the gel in a reaction kettle, performing hydrothermal reaction for 10-12 h at 120-140 ℃, performing vacuum filtration, taking a filter cake, washing the filter cake for 3-5 times by using deionized water, placing the filter cake in an oven at 60-80 ℃ for drying for 2-4 h, and grinding to obtain zirconium silicate powder.

The weight parts of the zirconium oxychloride, the tetraethoxysilane, the ammonia water and the deionized water are 40-50 parts of the zirconium oxychloride, 48-60 parts of the tetraethoxysilane, 16-20 parts of the ammonia water with the mass concentration of 1% and 240-300 parts of the deionized water.

The silicon nitride powder prepared in the step (2) comprises the following specific preparation steps:

(1) placing silicon dioxide powder and carbon powder in a stirrer, and stirring at the normal temperature at a rotating speed of 180-200 r/min for 20-30 min to obtain mixed powder;

(2) placing the mixed powder in a tubular atmosphere furnace, introducing nitrogen, heating to 1500-1600 ℃ from normal temperature under the power of 8-10 kW, carrying out heat preservation calcination for 1-2 h, and cooling to room temperature along with the furnace to obtain reaction powder;

(3) and (3) placing the reaction powder in a muffle furnace, heating to 600-800 ℃ from normal temperature at the heating rate of 5 ℃/min, carrying out heat preservation calcination for 40-60 min, and cooling to room temperature along with the furnace to obtain silicon nitride powder.

The silicon dioxide powder and the carbon powder are 30-40 parts by weight of silicon dioxide powder and 60-80 parts by weight of carbon powder.

And (3) introducing the nitrogen in the step (2) at a speed of 100-120 mL/min.

Compared with other methods, the method has the beneficial technical effects that:

(1) the invention takes silicon nitride as raw material to prepare the composite ceramic material for thermal protection connection, the silicon nitride ceramic is a ceramic material with good comprehensive performance, the silicon nitride is a superhard substance, has lubricity, wear resistance, is an atomic crystal, has good oxidation resistance and cold and hot impact resistance at high temperature, has very good electrical, thermal and mechanical properties, can be used to 1400 ℃ in an oxidizing atmosphere and can be used to 1850 ℃ in a neutral or reducing atmosphere, has the advantages of hardness, heat resistance, wear resistance and corrosion resistance of the common ceramic material, has the advantages of good thermal shock resistance, high temperature creep resistance, good self-lubrication, good chemical stability and the like, has relatively low density, low dielectric constant, good dielectric loss and the like, the electronegativity of silicon and nitrogen in the silicon nitride is similar, and Si-N in the silicon nitride crystal is mainly combined by covalent bonds, the silicon nitride is a covalent compound with high bond strength and can form an oxide protective film in the air, so the silicon nitride also has good chemical stability, and the silicon carbide is taken as a raw material, so that the reliability of the composite ceramic material for thermal protection connection can be effectively improved, and the composite ceramic material for thermal protection connection has good hardness and bearing capacity;

(2) the invention takes zirconium silicate as raw material to prepare the composite ceramic material for thermal protection connection, wherein the zirconium silicate is ZrO₂-SiO₂The only stable compound in the binary system, the zirconium silicate belongs to the tetragonal system and is a silicate mineral with an island structure, the molecular structure of the zirconium silicate is a rutile structure, silicon-oxygen tetrahedrons independently exist in the crystal structure of the zirconium silicate, the silicon-oxygen tetrahedrons are mutually linked through zirconium ions, each zirconium ion is filled among eight oxygen ions to form a zirconium-oxygen dodecahedron, the crystal lattice structure belongs to a tetragonal system, the crystal cell consists of four structural units, and the structure ensures that the zirconium silicate has the advantages of high melting point, low thermal conductivity, low thermal expansion coefficient, excellent chemical and phase stability and the like, the zirconium silicate ceramic has good slag resistance and is not easy to be infiltrated by slag, the zirconium silicate ceramic also has excellent thermal shock resistance, high temperature resistance and high mechanical strength, the zirconium silicate ceramic has a smaller linear expansion coefficient in a wider temperature range, and the zirconium silicate is thermally decomposed at high temperature.The amorphous silicon oxide can buffer the influence of the volume change of crystals to swell and shrink, and meanwhile, the decomposed silicon oxide can be combined with zirconium oxide again to generate zirconium silicate at a certain temperature, so that the monoclinic-phase zirconium oxide decomposed from the zirconium silicate can not generate obvious stress change when the monoclinic-phase zirconium oxide is subjected to phase change as a pure zirconium oxide material, and therefore, the composite ceramic material for thermal protection connection prepared by taking the zirconium silicate as a raw material has good bearing capacity and reliability.

Detailed Description

Respectively weighing 30-40 parts of silicon dioxide powder and 60-80 parts of carbon powder according to parts by weight, placing the silicon dioxide powder and the carbon powder in a stirrer, stirring at a rotating speed of 180-200 r/min for 20-30 min at normal temperature to obtain mixed powder, placing the mixed powder in a tubular atmosphere furnace, introducing nitrogen at an air flow rate of 100-120 mL/min, heating from normal temperature to 1500-1600 ℃ under the power of 8-10 kW, carrying out heat preservation and calcination for 1-2 h, cooling to room temperature along with the furnace to obtain reaction powder, placing the reaction powder in a muffle furnace, heating from normal temperature to 600-800 ℃ at a heating rate of 5 ℃/min, carrying out heat preservation and calcination for 40-60 min, and cooling to room temperature along with the furnace to obtain silicon nitride powder; then respectively weighing 40-50 parts by weight of zirconium oxychloride, 48-60 parts by weight of ethyl orthosilicate, 16-20 parts by weight of 1% ammonia water and 240-300 parts by weight of deionized water, adding the zirconium oxychloride into 1/2 parts by weight of deionized water, stirring at the normal temperature at the rotating speed of 200-240 r/min for 12-16 min to obtain a zirconium oxychloride solution, adding the ethyl orthosilicate and the ammonia water into the rest 1/2 parts of deionized water, stirring at the rotating speed of 240-280 r/min for 1-2 h at the normal temperature to obtain a sol, adding the zirconium oxychloride solution into the sol, stirring at the rotating speed of 200-240 r/min for 40-60 min under the water bath condition of 40-60 ℃, standing for 1-2 h to obtain a gel, placing the gel into a reaction kettle, carrying out hydrothermal reaction at the temperature of 120-140 ℃ for 10-12 h, carrying out vacuum filtration, taking a filter cake, washing with deionized water for 3-5 times, placing the filter cake into a 60-80 ℃ oven, drying for 2-4 h, grinding to obtain zirconium silicate powder; then respectively weighing 40-60 parts of silicon nitride powder, 20-30 parts of zirconium silicate powder, 8-12 parts of carbon fiber, 2-3 parts of polyvinyl alcohol, 0.4-0.6 part of sodium dodecyl benzene sulfonate, 0.2-0.3 part of calcium oxide powder, 0.2-0.3 part of magnesium oxide powder, 40-60 parts of absolute ethyl alcohol and 40-60 parts of deionized water according to parts by weight, adding the polyvinyl alcohol, the sodium dodecyl benzene sulfonate and the absolute ethyl alcohol into the deionized water, stirring at the rotating speed of 200-240 r/min at normal temperature for 10-12 min to obtain a mixed solution, adding the silicon nitride powder, the zirconium silicate powder, the carbon fiber, the calcium oxide powder and the magnesium oxide powder into the mixed solution, placing the mixed solution into a ball mill, ball-milling at the rotating speed of 200-250 r/min at normal temperature for 1-2 h, placing the ball mill into an ultrasonic dispersion machine, ultrasonically oscillating at the power of 400-500W for 30-40 min to obtain a mixed slurry, placing the mixed slurry into an oven at the temperature of 100-120 ℃ for drying for 2-4 h, and cooling at normal temperature to obtain mixed powder, placing the mixed powder in a press, dry-pressing and molding the powder at the normal temperature under the pressure of 240-280 MPa, maintaining the pressure for 30-40 s to obtain a biscuit, placing the biscuit in a microwave sintering furnace, raising the temperature from the normal temperature to 600-800 ℃ at the temperature rise rate of 10 ℃/min, pre-sintering for 40-60 min, rapidly raising the temperature to 1500-1600 ℃ at the temperature rise rate of 50 ℃/min, carrying out heat preservation and sintering for 1-2 h, and cooling to the room temperature along with the furnace to obtain the composite ceramic material for thermal protection connection.