High temperature composite for a flame synthesis apparatus

Abstract

The application relates to a high-temperature composite material for a flame synthesis device, and relates to the technical field of high-temperature composite materials, which comprises the following components in mass fractions: modified ceramic powder 50-70 parts, coupling agent modified zirconium oxide fiber 10-20 parts, oxidized modified carbon fiber 8-12 parts, lanthana 1-3 parts and ceria 2-4 parts. The high-temperature composite material for the flame synthesis device prepared by the application has low brittleness, good thermal shock stability and high density, has good corrosion resistance, and can long-term maintain good working performance in the complex working environment of the flame synthesis device.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of high-temperature composite materials, in particular to a high-temperature composite material for a flame synthesis device. BACKGROUND

[0002] High-temperature composite materials have good economic value and are widely used in many fields. In aerospace, ceramic-based and carbon / carbon composite materials provide high-temperature resistance for key components of aircraft and spacecraft, ensuring flight safety and exploration, and promoting industrial development; in the energy field, they help power generation and new energy research and development, and in the automotive manufacturing field, they use metal-based high-temperature materials to achieve lightweighting, improve performance and competitiveness; in the chemical and metallurgical industries, they maintain device operation, achieve quality improvement and cost reduction. The rise of high-temperature material industry also drives the upstream and downstream industries, creates employment and stimulates economic growth.

[0003] High-temperature composite materials have their own advantages. Ceramic-based composite materials have high hardness, good wear resistance and excellent high-temperature resistance, low thermal expansion coefficient, stable size under temperature change and good oxidation resistance, with ceramic as the matrix and carbon fiber, silicon carbide fiber, etc. as the reinforcing phase; carbon / carbon composite materials, composed of carbon fiber reinforcement and carbon matrix, can withstand high temperatures of over 2000℃ in a non-oxidizing atmosphere, have high thermal conductivity and are beneficial to heat conduction; metal-based composite materials have good toughness, plasticity and impact resistance, with nickel-based, cobalt-based and titanium-based alloys as the matrix and ceramic particles or fibers as the reinforcing phase, and nickel-based high-temperature alloys can withstand high temperatures of 800-1000℃ and have good processing performance, allowing the formation of complex shapes. However, these materials still have many problems in practical application.

[0004] Ceramic-based composite materials have brittleness problems, which cause many difficulties in the actual operation of flame synthesis devices. In the complex thermal and mechanical stress environment inside the flame synthesis device, ceramic-based composite materials are difficult to effectively cope with the frequent changes and concentrated effects of stress due to their own brittle nature. Under the combined action of these stresses, cracks may occur and expand, and in severe cases, even breakage may occur. This not only directly causes damage to the key components of the device, requiring frequent maintenance and replacement of parts, but also may cause safety accidents such as loss of control of reaction conditions and leakage of materials, so improvement is needed. SUMMARY

[0005] In order to reduce the brittleness of ceramic-based composite materials, the application provides a high-temperature composite material for a flame synthesis device.

[0006] The high-temperature composite material for a flame synthesis device provided by the application adopts the following technical scheme:

[0007] A high-temperature composite material for a flame synthesis device comprises the following components by mass fraction:

[0008] Modified ceramic powder 50-70 parts

[0009] Coupling agent modified zirconia fiber 10-20 parts

[0010] Oxidation modified carbon fiber 8-12 parts

[0011] Lanthanum oxide 1-3 parts

[0012] Cerium oxide 2-4 parts.

[0013] The coupling agent modified zirconia fiber builds a micro-reinforced network in the material due to its high strength and high toughness. When the material is subjected to external force or encounters a sharp change in temperature, these fibers can effectively prevent the propagation of cracks by bridging, pulling out and other mechanisms, thereby reducing the brittleness of the material and improving the thermal shock stability. The oxidation modified carbon fiber further complements and strengthens this toughening system, and its interweaving and synergistic effect with the zirconia fiber enhances the crack resistance. Lanthanum oxide and cerium oxide can reduce the sintering temperature of the material, promote better fusion and densification between components, reduce the formation and retention of pores during the sintering process, and improve the density of the material, so that it can better resist the impact and damage of external force and reduce the channels for the corrosion medium to enter the material. The synergistic effect of the components in the high-temperature composite material reduces the brittleness of the material, improves the thermal shock stability and density, and further enhances the corrosion resistance, so that the high-temperature composite material can perform well in the flame synthesis device for a long time. Compared with traditional quartz materials for flame synthesis devices, the high-temperature composite material is more solid and durable. The quartz material is brittle and easily broken, while the high-temperature composite material builds a stable micro-reinforced network, and the components synergistically resist external forces. Whether it is tensile, compressive or shear stress, it can maintain structural integrity, density and corrosion-resistant component barriers, effectively block the entry of corrosive media, maintain material performance for a long time, and prolong the service life, providing a solid guarantee for production and operation.

[0014] Preferably, the modified ceramic powder is prepared by the following steps:

[0015] The ceramic powder is washed to obtain a pretreated ceramic powder; the pretreated ceramic powder and a release agent are ball milled to obtain a mixture; and the mixture is subjected to nitriding treatment to obtain a modified ceramic powder.

[0016] The cleaning can remove the surface impurities and pollutants of the ceramic powder, reduce the defect source, and lay a foundation for subsequent uniform mixing and good performance; the release agent can effectively prevent the powder from agglomeration and caking during the ball milling process and the nitriding process, so that the components are uniformly dispersed, which is beneficial to form a homogeneous structure and avoid stress concentration phenomenon caused by local unevenness, thereby reducing brittleness and improving thermal shock stability; the nitriding treatment makes the ceramic matrix form nitride phase, the nitride has high hardness and good chemical stability, which can enhance the strength and corrosion resistance of the matrix, at the same time, the generation of the nitride phase optimizes the crystal structure of the ceramic matrix, promotes the close combination with other components, improves the density of the material, reduces the porosity, further enhances the overall corrosion resistance of the material, and makes the high-temperature composite material have good durability in the flame synthesis device.

[0017] Preferably, the ceramic powder comprises zirconium boride powder and silicon carbide powder.

[0018] Zirconium boride has high melting point, high hardness and good chemical stability, and silicon carbide has excellent high-temperature strength and oxidation resistance, and the two cooperate to form a stable and strong structure framework of the ceramic matrix; the high strength characteristics of zirconium boride and silicon carbide can effectively share and transfer external stress, prevent the rapid expansion of cracks in the matrix, thereby reducing the brittleness of the material as a whole; the stable crystal structure and high thermal conductivity formed by the two help to quickly and uniformly disperse heat when the temperature changes sharply, reduce the damage of the material caused by local thermal stress, and improve the thermal shock resistance; zirconium boride and silicon carbide can be closely combined when sintering, reduce the formation of internal pores, and improve the density of the material, and the dense structure effectively blocks the invasion of corrosive media, thereby enhancing the corrosion resistance of the material and ensuring the long-term stable operation of the high-temperature composite material in the flame synthesis device.

[0019] Preferably, the mass ratio of the zirconium boride powder, the silicon carbide powder and the release agent is 1:(0.5-1):0.08.

[0020] The modified ceramic powder prepared according to the above mass ratio has good performance, which can effectively reduce the brittleness of the high-temperature composite material, improve the thermal shock stability and density.

[0021] Preferably, the release agent comprises aluminum oxide and yttrium oxide.

[0022] Alumina has high hardness, high melting point and good chemical stability, and yttrium oxide can effectively reduce the sintering temperature and promote densification; during the ball milling mixing stage, alumina and yttrium oxide are uniformly distributed between the ceramic powder, effectively preventing powder agglomeration, ensuring uniform dispersion of each component, helping to form a homogeneous material structure, avoiding local inhomogeneity stress concentration, thereby reducing material brittleness and improving thermal shock stability; during the nitriding process, alumina and yttrium oxide can form a protective film on the surface of ceramic powder particles, preventing excessive sintering or adhesion of the powder under high-temperature nitriding environment, allowing nitrogen atoms to more uniformly and smoothly diffuse into the ceramic matrix powder, which is conducive to the formation of stable and appropriate nitride phases, thereby refining the grains during subsequent sintering, enhancing the grain boundary bonding force, effectively hindering crack initiation and propagation, further reducing the brittleness of high-temperature composites and improving thermal shock stability, reducing porosity and improving density.

[0023] Preferably, the nitriding treatment conditions are a nitriding temperature of 900-1100℃, a nitriding time of 6-8h, and a nitriding atmosphere of nitrogen and ammonia in a volume ratio of 1:(0.4-0.6), with a gas flow rate of 1-3L / min.

[0024] Nitriding treatment under the above conditions facilitates the uniform and sufficient diffusion of nitrogen atoms into the ceramic matrix powder, forming stable and appropriate nitride phases; the generation of appropriate nitride phases can effectively refine the matrix grains and enhance the grain boundary bonding force, effectively hindering crack initiation and propagation when the material is stressed, thereby reducing brittleness and improving thermal shock stability; at the same time, this uniform nitriding process promotes the further close arrangement of the components of the ceramic matrix powder, reducing porosity and improving density, and the dense structure can effectively block the penetration of corrosive media, combined with the good chemical stability of the nitride phase itself, further improving the overall corrosion resistance of the material, allowing the high-temperature composite material to better adapt to the harsh working conditions of high temperature, corrosion, etc. in the flame synthesis device.

[0025] Preferably, the preparation raw materials of the coupling agent modified zirconia fiber include the zirconia fiber body, hydrofluoric acid and titanate coupling agent.

[0026] The hydrogen fluoride etches the zirconia fiber to form a micro-rough structure on the surface, thereby increasing the specific surface area and active sites. The introduced titanate coupling agent can be closely combined with the active sites, with one end connected to the zirconia fiber and the other end having a good affinity with the ceramic matrix powder, thereby improving the dispersibility of the zirconia fiber in the matrix and enhancing the compatibility between the zirconia fiber and the ceramic matrix powder. The interface between the two is more closely combined, so that the two can more effectively bear and transfer stress, inhibit the generation and propagation of cracks, reduce the brittleness of the material, and improve the thermal shock stability. Due to the uniform dispersion of the fiber and the close interface combination, the material is more likely to form a dense structure during preparation, reducing porosity and improving density. Combined with the chemical stability of the zirconia fiber itself, the two work together to effectively prevent the intrusion of corrosive media, thereby improving the corrosion resistance of the material and enabling the high-temperature composite material to better adapt to the complex working environment of the flame synthesis device and maintain excellent performance.

[0027] Preferably, the coupling agent modified zirconia fiber is prepared by the following steps:

[0028] A hydrogen fluoride solution is prepared, and the zirconia fiber body is placed in the prepared hydrogen fluoride solution and stirred and soaked. After etching is completed, the etched fiber is separated, washed with water until the pH is neutral, and a preliminary modified zirconia fiber is obtained. The titanate coupling agent is mixed with isopropyl alcohol to obtain a coupling agent solution. The preliminary modified zirconia fiber is soaked in the coupling agent solution, heated and stirred, and after soaking is completed, the soaked fiber is separated, washed, and dried to obtain the coupling agent modified zirconia fiber.

[0029] The coupling agent modified zirconia fiber prepared according to the above steps has good dispersibility and compatibility. During the modification of the zirconia fiber, the titanate coupling agent is combined with the active sites on the surface of the zirconia fiber after hydrogen fluoride etching through chemical bonding, thereby improving the dispersibility and compatibility of the fiber. During sintering, as the temperature rises, the titanate coupling agent will decompose, and the titanium element can participate in the material migration and reaction during sintering to form titanium compounds, which act as a new grain boundary phase, filling the gaps between the matrix particles, promoting the growth of the neck between the particles, accelerating the sintering process, making the material more dense, reducing the porosity of the material, improving the density of the material, reducing the brittleness of the material, and improving the thermal shock stability. The grain boundary phase formed by the titanium element can improve the structure and performance of the grain boundary. When the material is subjected to external force or thermal stress, the strengthened grain boundary can effectively hinder the propagation of cracks. At the same time, due to the good chemical stability of the grain boundary phase formed by the titanium element, it can prevent the corrosion medium from invading the interior of the material along the grain boundary. This corrosion resistance mechanism, combined with the corrosion resistance of the dense structure of the material, improves the corrosion resistance of the material, enabling the material to maintain good performance in high-temperature and corrosive environments such as flame synthesis devices.

[0030] Preferably, the oxidized modified carbon fiber is prepared by the following steps:

[0031] A modified aqueous solution containing hydrogen peroxide and sodium hydroxide is prepared, carbon fibers are added to the modified aqueous solution, heated and stirred for soaking, and the modified fibers are separated, washed and dried to obtain the oxidized modified fibers.

[0032] According to the above modification process, the surface of the carbon fiber is oxidized and etched to form a large number of active functional groups and rough structures, thereby enhancing the interfacial bonding force between the carbon fiber and the ceramic matrix. When the high-temperature composite material is stressed, the carbon fiber can more effectively transfer and disperse stress, consume energy through its own deformation, fracture and pull-out mechanism, effectively prevent crack propagation, thereby reducing the brittleness of the material and improving the thermal shock stability. At the same time, the good interfacial bonding promotes the densification process of the material during preparation, reduces the formation of internal pores, improves the density, and enhances the chemical stability of the oxidized modified carbon fiber. The dense structure can effectively block the penetration of corrosive media, and the synergistic effect of the two improves the corrosion resistance of the material, so that the high-temperature composite material for flame synthesis device has better durability and reliability in high-temperature and corrosive environment.

[0033] Preferably, the high-temperature composite material for flame synthesis device is prepared by the following steps:

[0034] Lanthanum oxide and cerium oxide are added to the modified ceramic powder to obtain a premix; the coupling agent modified zirconium oxide fiber and the oxidized modified carbon fiber are added to the premix to obtain a mixture; the mixture is placed in a mold and cold isostatic pressed to obtain a green body; the green body is sintered under inert gas protection, and after furnace cooling, the high-temperature composite material for flame synthesis device is obtained.

[0035] The high-temperature composite material for flame synthesis device prepared according to the above steps has low brittleness, good thermal shock stability and high density, has good corrosion resistance, and can maintain good working performance in high-temperature and corrosive environment of the flame synthesis device for a long time.

[0036] In summary, the present application includes at least one of the following beneficial technical effects:

[0037] 1. Coupling agent modified zirconia fiber with high strength and high toughness, builds a micro-reinforced network in the material, when the material is subjected to external force or encounters a sharp change in temperature, these fibers can effectively prevent the propagation of cracks by bridging, pulling out and other mechanisms, reducing the brittleness of the material and improving the thermal shock stability; Oxidized carbon fiber further complements and strengthens this toughening system, which interweaves with zirconia fiber and synergizes to enhance the crack resistance; Lanthanum oxide and cerium oxide can reduce the sintering temperature of the material, promote better fusion and densification between components, reduce the formation and retention of pores during sintering, and improve the density of the material, so that it can better resist the impact and damage of external force and reduce the channels for corrosion medium to enter the material; The components in the high-temperature composite material synergize to reduce the brittleness of the material, improve the thermal shock stability and density, and thus enhance the corrosion resistance, so that the high-temperature composite material can perform well in the flame synthesis device for a long time; Compared with traditional quartz materials for flame synthesis devices, high-temperature composites are more solid and durable, quartz materials are brittle and easy to break, while high-temperature composites build a stable micro-reinforced network, and the components synergistically resist external forces, whether it is tension, compression or shear stress, it can maintain structural integrity, dense structure and corrosion-resistant component barrier, effectively block the invasion of corrosive media, maintain material performance for a long time, and prolong the service life, providing a solid guarantee for production and operation.

[0038] 2. The release agent effectively prevents powder agglomeration and caking during ball milling and nitriding, allowing uniform dispersion of components, which is beneficial to the formation of a homogeneous structure and avoids stress concentration caused by local inhomogeneity, thereby reducing brittleness and improving thermal shock stability; Nitriding treatment forms nitride phases in the ceramic matrix, which have high hardness and good chemical stability, enhancing the strength and corrosion resistance of the matrix. At the same time, the formation of nitride phases optimizes the crystal structure of the ceramic matrix, promotes close bonding with other components, improves the density of the material, reduces porosity, and further enhances the overall corrosion resistance of the material, making the high-temperature composite material have good durability in the flame synthesis device.

[0039] 3. In the modification stage of zirconia fibers, the titanate coupling agent is combined with the active sites on the surface of the zirconia fibers etched by hydrofluoric acid through chemical bond, improving the dispersibility and compatibility of the fibers; during the sintering process, as the temperature rises, the titanate coupling agent will decompose, and the titanium element can participate in the material migration and reaction during sintering, forming titanium compounds as a new grain boundary phase, filling the gaps between the matrix particles, promoting the neck growth between the particles, accelerating the sintering process, making the material more dense, reducing the porosity of the material, improving the density of the material, reducing the brittleness of the material, and improving the thermal shock stability; the grain boundary phase formed by the titanium element can improve the structure and performance of the grain boundary, and the strengthened grain boundary can effectively hinder the propagation of cracks when the material is subjected to external force or thermal stress. At the same time, due to the good chemical stability of the grain boundary phase formed by the titanium element, it can prevent the corrosion medium from invading the interior of the material along the grain boundary. This corrosion resistance mechanism combined with the corrosion resistance of the dense structure of the material improves the corrosion resistance of the material, so that the material can maintain good performance in high-temperature and corrosive environments such as flame synthesis devices. DETAILED DESCRIPTION

[0040] The application discloses a high-temperature composite material for a flame synthesis device. The raw materials used in the application can be obtained through commercially available raw materials, except for special instructions. The application is further described in detail in conjunction with the embodiments as follows:

[0041] Raw material description: The length of the zirconia fiber is 300 μm, the diameter is 0.1 μm, the length of the carbon fiber is 500 μm, the diameter is 5 μm, the titanate coupling agent is KR-41B type coupling agent (CAS number: 65460-52-8), and the silane coupling agent is KH-550 (CAS number: 919-30-2).

[0042] Embodiment 1

[0043] Preparation of modified ceramic powder

[0044] The zirconium boride powder and the silicon carbide powder are washed with deionized water and anhydrous ethanol respectively for three times to obtain pretreated ceramic powder; the pretreated ceramic powder and the release agent are added into a ball mill, and ball milling is performed at a material to zirconia ball mass ratio of 1:3 to obtain a mixed powder, the mass ratio of the zirconium boride powder, the silicon carbide powder and the release agent is 1:0.5:0.08, and the mass ratio of the aluminum oxide and the yttrium oxide in the release agent is 1:1; the mixed material is subjected to nitriding treatment, the nitriding temperature is 900°C, the nitriding time is 8h, the nitriding atmosphere is nitrogen and ammonia at a volume ratio of 1:0.6, and the gas flow is 3L / min, to obtain a modified ceramic powder.

[0045] Preparation of coupling agent modified zirconia fiber

[0046] A 10% hydrofluoric acid solution was prepared, and the zirconia fibers were placed in the prepared hydrofluoric acid solution, with a solid-liquid ratio of 1:5, and stirred at a speed of 50 rpm for 60 min. After the soaking was completed, the etched fibers were separated, washed with deionized water until the pH was neutral, and a preliminary modified zirconia fiber was obtained. A titanate coupling agent was mixed with isopropyl alcohol at a volume ratio of 1:10 to obtain a coupling agent solution. The preliminary modified zirconia fiber was soaked in the coupling agent solution, with a solid-liquid ratio of 1:10, and stirred at a speed of 100 rpm at 60°C for 4 h. After the soaking was completed, the soaked fiber was separated, washed with deionized water, and dried at 120°C for 2 h to obtain a coupling agent modified zirconia fiber.

[0047] Preparation of oxidation modified carbon fiber

[0048] A modified aqueous solution was prepared, with a mass concentration of hydrogen peroxide of 30% and a concentration of sodium hydroxide of 1 mol / L. The carbon fiber was added to the modified aqueous solution, and soaked at 40°C with stirring at a speed of 50 rpm for 2 h. The modified fiber was separated, washed with deionized water, and dried at 80°C for 4 h to obtain an oxidation modified fiber.

[0049] Preparation of high-temperature composite material for flame synthesis device

[0050] 1 kg of lanthanum oxide and 2 kg of cerium oxide were added to 50 kg of modified ceramic powder, and stirred in a high-speed blender at a speed of 1000 rpm for 30 min to obtain a premix. 10 kg of coupling agent modified zirconia fiber and 8 kg of oxidation modified carbon fiber were added to the premix, and stirred at a speed of 800 rpm for 30 min to obtain a mixture. The mixture was placed in a mold and cold isostatic pressed, with a pressure of 300 MPa and a holding time of 8 min to obtain a green body. The green body was placed in a high-temperature sintering furnace and sintered, with an argon atmosphere, a temperature increase rate of 10°C / min to 1000°C, a temperature increase rate of 8°C / min to 1500°C, and a temperature increase rate of 5°C / min to 2000°C, and a holding time of 3 h. After cooling in the furnace, a high-temperature composite material for a flame synthesis device was obtained.

[0051] Example 2

[0052] Preparation of modified ceramic powder

[0053] The zirconium boride powder and the silicon carbide powder are washed with deionized water and anhydrous ethanol respectively for three times to obtain pretreated ceramic powder; the pretreated ceramic powder and the release agent are added into a ball mill, and the ball milling is carried out at a material to zirconia ball mass ratio of 1:3 to obtain a mixed powder, the mass ratio of the zirconium boride powder, the silicon carbide powder and the release agent being 1:1:0.08, and the mass ratio of the aluminum oxide and the yttrium oxide in the release agent being 1:1; the mixed powder is subjected to nitriding treatment, the nitriding temperature being 1100℃, the nitriding time being 6h, the nitriding atmosphere being nitrogen and ammonia at a volume ratio of 1:0.4, and the gas flow being 1L / min, to obtain modified ceramic powder.

[0054] Preparation of coupling agent modified zirconia fiber

[0055] A hydrofluoric acid solution with a mass concentration of 10% is prepared, and the zirconia fiber is placed in the prepared hydrofluoric acid solution, the solid-liquid ratio being 1:5, and the stirring and soaking are carried out at a speed of 50rpm for 60min; after the soaking is completed, the etched fiber is separated, washed with deionized water until the pH is neutral, to obtain preliminary modified zirconia fiber; a titanate coupling agent is mixed with isopropyl alcohol at a volume ratio of 1:10 to obtain a coupling agent solution; the preliminary modified zirconia fiber is soaked in the coupling agent solution, the solid-liquid ratio being 1:10, and the stirring and soaking are carried out at a speed of 100rpm at 60℃ for 4h; after the soaking is completed, the soaked fiber is separated, washed with deionized water, and dried at 120℃ for 2h, to obtain coupling agent modified zirconia fiber.

[0056] Preparation of oxidation modified carbon fiber

[0057] A modified aqueous solution is prepared, the mass concentration of hydrogen peroxide in the modified aqueous solution being 30% and the concentration of sodium hydroxide being 1mol / L; the carbon fiber is added into the modified aqueous solution, and the stirring and soaking are carried out at a speed of 50rpm at 40℃ for 2h; the modified treated fiber is separated, washed with deionized water, and dried at 80℃ for 4h, to obtain oxidation modified fiber.

[0058] Preparation of high-temperature composite material for flame synthesis device

[0059] 3kg lanthanum oxide and 4kg cerium oxide were added to 70kg modified ceramic powder, and stirred in a high-speed mixer at a speed of 1000rpm for 30min to obtain a premix; 20kg coupling agent modified zirconia fiber and 12kg oxidized modified carbon fiber were added to the premix, and stirred at a speed of 800rpm for 30min to obtain a mixture; the mixture was placed in a mold and cold isostatic pressed to form a green body, with a pressure of 300MPa and a holding time of 8min; the green body was placed in a high-temperature sintering furnace for sintering, with an argon atmosphere, a temperature rising rate of 10℃ / min to 1000℃, a temperature rising rate of 8℃ / min to 1500℃, and a temperature rising rate of 5℃ / min to 2000℃, and holding for 3h, and then cooled in the furnace to obtain a high-temperature composite material for flame synthesis device.

[0060] Example 3

[0061] Preparation of modified ceramic powder

[0062] The zirconium boride powder and the silicon carbide powder were washed with deionized water and anhydrous ethanol respectively for three times to obtain pretreated ceramic powder; the pretreated ceramic powder and a release agent were added to a ball mill for ball milling at a material to zirconia ball mass ratio of 1:3 to obtain a mixed powder, with a mass ratio of zirconium boride powder, silicon carbide powder and release agent of 1:0.75:0.08, and a mass ratio of aluminum oxide and yttrium oxide in the release agent of 1:1; the mixed powder was subjected to nitriding treatment at a temperature of 1000℃ for 7h in a nitriding atmosphere of nitrogen and ammonia at a volume ratio of 1:0.5, with a gas flow rate of 2L / min to obtain modified ceramic powder.

[0063] Preparation of coupling agent modified zirconia fiber

[0064] A hydrofluoric acid solution with a mass concentration of 10% was prepared, and the zirconia fiber was placed in the prepared hydrofluoric acid solution at a solid to liquid ratio of 1:5, and stirred at a speed of 50rpm for 60min of soaking; after the soaking was completed, the etched fiber was separated, washed with deionized water until the pH was neutral to obtain preliminarily modified zirconia fiber; a titanate coupling agent was mixed with isopropyl alcohol at a volume ratio of 1:10 to obtain a coupling agent solution; the preliminarily modified zirconia fiber was soaked in the coupling agent solution at a solid to liquid ratio of 1:10, and stirred at a speed of 100rpm at 60℃ for 4h of soaking; after the soaking was completed, the soaked fiber was separated, washed with deionized water, and dried at 120℃ for 2h to obtain coupling agent modified zirconia fiber.

[0065] Preparation of oxidized modified carbon fiber

[0066] A modified aqueous solution is configured, the mass concentration of hydrogen peroxide in the modified aqueous solution is 30%, and the concentration of sodium hydroxide is 1 mol / L. Carbon fibers are added into the modified aqueous solution, and the carbon fibers are soaked at 40°C and a stirring speed of 50 rpm for 2 h. The modified fibers are separated, washed with deionized water, and dried at 80°C for 4 h to obtain the oxidized modified fibers.

[0067] High-temperature composite material for flame synthesis device

[0068] 2 kg of lanthanum oxide and 3 kg of cerium oxide are added into 60 kg of modified ceramic powder, and stirred in a high-speed blender at a speed of 1000 rpm for 30 min to obtain a premix. 15 kg of coupling agent modified zirconium oxide fibers and 10 kg of oxidized modified carbon fibers are added into the premix, and stirred at a speed of 800 rpm for 30 min to obtain a mixture. The mixture is placed into a mold and cold isostatic pressed to form a green body at a pressure of 300 MPa and a holding time of 8 min. The green body is sintered in a high-temperature sintering furnace, heated to 1000°C at a speed of 10°C / min, heated to 1500°C at a speed of 8°C / min, and heated to 2000°C at a speed of 5°C / min, and held for 3 h. After cooling in the furnace, a high-temperature composite material for a flame synthesis device is obtained.

[0069] Example 4

[0070] Example 4 is based on Example 3, and the only difference between Example 4 and Example 3 is that the mass ratio of zirconium boride powder, silicon carbide powder, and release agent in Example 4 is 1:0.2:0.08.

[0071] Example 5

[0072] Example 5 is based on Example 3, and the only difference between Example 5 and Example 3 is that the mass ratio of zirconium boride powder, silicon carbide powder, and release agent in Example 5 is 1:1.5:0.08.

[0073] Example 6

[0074] Example 6 is based on Example 3, and the only difference between Example 6 and Example 3 is that the nitriding temperature in Example 6 is 800°C, the nitriding time is 10 h, and the nitriding atmosphere is a mixture of nitrogen and ammonia at a volume ratio of 1:0.7, and the gas flow rate is 4 L / min.

[0075] Example 7

[0076] Example 7 is based on Example 3, and the only difference between Example 7 and Example 3 is that the nitriding temperature in Example 7 is 1200°C, the nitriding time is 5 h, and the nitriding atmosphere is a mixture of nitrogen and ammonia at a volume ratio of 1:0.3, and the gas flow rate is 0.8 L / min.

[0077] Example 8

[0078] Example 8 is based on Example 3, the difference between Example 8 and Example 3 is that no zirconium boride powder is added in the preparation of the modified ceramic powder in Example 8, the rest is made up with silicon carbide.

[0079] Example 9

[0080] Example 9 is based on Example 3, the difference between Example 9 and Example 3 is that no yttrium oxide is added in the release agent in Example 9, the rest is made up with aluminum oxide.

[0081] Example 10

[0082] Example 10 is based on Example 3, the difference between Example 10 and Example 3 is that no hydrofluoric acid is used for etching in the preparation of the coupling agent modified zirconia fiber in Example 10.

[0083] Example 11

[0084] Example 11 is based on Example 3, the difference between Example 11 and Example 3 is that the titanate coupling agent is replaced by silane coupling agent in the preparation of the coupling agent modified zirconia fiber in Example 11.

[0085] Comparative Example 1

[0086] Comparative Example 1 is based on Example 3, the difference between Comparative Example 1 and Example 3 is that the modified ceramic powder is replaced by zirconium boride powder and silicon carbide powder with a mass ratio of 1:1 in Comparative Example 1.

[0087] Comparative Example 2

[0088] Comparative Example 2 is based on Example 3, the difference between Comparative Example 2 and Example 3 is that the coupling agent modified zirconia fiber is replaced by zirconia fiber in Comparative Example 2.

[0089] Comparative Example 3

[0090] Comparative Example 3 is based on Example 3, the difference between Comparative Example 3 and Example 3 is that the oxidation modified carbon fiber is replaced by carbon fiber in Comparative Example 3.

[0091] Comparative Example 4

[0092] Comparative Example 4 is based on Example 3, the difference between Comparative Example 4 and Example 3 is that no lanthanum oxide is added in Comparative Example 4.

[0093] Comparative Example 5

[0094] Comparative Example 5 is based on Example 3, the difference between Comparative Example 5 and Example 3 is that no cerium oxide is added in Comparative Example 5.

[0095] Performance detection test

[0096] (1) Select GB / T 44537-2024 Fine Ceramic Room Temperature Fracture Toughness Test Method Surface Crack Bending Beam (SCF) Method as the standard, test the fracture toughness of the sample, prepare three samples for each sample, take the average value after measurement, and record the results in Table 1.

[0097] (2) Select GB / T 16535-1996 Engineering Ceramic Linear Thermal Expansion Coefficient Test Method as the standard, test the linear thermal expansion coefficient of the sample, test three times for each sample, take the average value after measurement, and record the results in Table 1.

[0098] (3) Density test: use Archimedes drainage method to test and calculate the relative density of the sample, test three times for each sample, take the average value after measurement, and record the results in Table 1.

[0099] Table 1 Detection results of brittleness, thermal shock stability and density of high temperature composite material

[0100]

[0101]

[0102] From Table 1, the fracture toughness of Examples 1-3 is greater than 9.3 MPa·m 1 / 2 , the linear thermal expansion coefficient is less than 1.82×10 -6 / ℃, and the relative density is greater than 98.9%, so it can be seen that the high temperature composite material prepared by the flame synthesis device has low brittleness, good thermal shock stability and high density.

[0103] From Table 1, the difference between Examples 4, 5 and Example 3 is only that in Example 4, the mass ratio of zirconium boride powder, silicon carbide powder and release agent is 1:0.2:0.08, and in Example 5, the mass ratio of zirconium boride powder, silicon carbide powder and release agent is 1:1.5:0.08, and the performance of Examples 4, 5 and Example 3 is decreased; This is because too much or too little silicon carbide powder will affect the internal structure of the high temperature composite material, destroy the balance of the performance between the components, and thus weaken the synergistic effect of the material, increase the brittleness, and decrease the thermal shock stability and density.

[0104] From Table 1, it can be seen that the difference between Example 6, 7 and Example 3 is only that the nitriding temperature in Example 6 is 800℃, the nitriding time is 10h, the nitriding atmosphere is nitrogen and ammonia with a volume ratio of 1:0.7, and the gas flow rate is 4L / min, the nitriding temperature in Example 7 is 1200℃, the nitriding time is 5h, the nitriding atmosphere is nitrogen and ammonia with a volume ratio of 1:0.3, and the gas flow rate is 0.8L / min, the performance of Example 6, 7 and Example 3 has decreased; this is because changing the nitriding conditions will affect the uniformity of nitrogen atom diffusion and the amount of nitride, and then affect the arrangement of each component and the crystal phase structure in the sintering process, so that the brittleness, thermal shock stability and density of the material are affected.

[0105] From Table 1, it can be seen that the difference between Example 8, 9 and Example 3 is only that no zirconium boride powder is added when preparing the modified ceramic powder in Example 8, and no yttrium oxide is added in the release agent in Example 9, the performance of Example 8, 9 and Example 3 has decreased; this is because without adding zirconium boride, the synergistic effect between components is lacking, the material is more prone to damage, and the density between components also decreases; lacking yttrium oxide, the synergistic effect of aluminum oxide is weakened, and the performance is decreased in the process of ball milling, nitriding treatment and sintering.

[0106] From Table 1, it can be seen that the difference between Example 10, 11 and Example 3 is only that no hydrofluoric acid is used for etching when preparing the coupling agent modified zirconia fiber in Example 10, and the titanate coupling agent is replaced by silane coupling agent when preparing the coupling agent modified zirconia fiber in Example 11, the performance of Example 10, 11 and Example 3 has decreased; this is because without using hydrofluoric acid for etching, the active sites on the surface of the zirconia fiber are limited, and the modification effect decreases; replacing the titanate coupling agent with the silane coupling agent, lacking the role of titanium element in the grain boundary phase, the brittleness of the high-temperature composite material increases, and the thermal shock stability and density decrease.

[0107] From Table 1, it can be seen that the difference between Comparative Examples 1-3 and Example 3 is only that the modified ceramic powder is replaced by zirconium boride powder and silicon carbide powder with a mass ratio of 1:1 in Comparative Example 1, the coupling agent modified zirconia fiber is replaced by zirconia fiber in Comparative Example 2, and the oxidation modified carbon fiber is replaced by carbon fiber in Comparative Example 3, the performance of Comparative Examples 1-3 and Example 3 has decreased; this is because lacking modification treatment, the dispersibility and compatibility between components decrease, the interfacial bonding force weakens, and local stress concentration is easy to cause damage, so that the brittleness increases, and the thermal shock stability and density decrease.

[0108] From Table 1, it can be seen that the difference between Comparative Examples 4 and 5 and Example 3 is that Comparative Example 4 does not add lanthanum oxide and Comparative Example 5 does not add cerium oxide, and the performance of Comparative Examples 4 and 5 is decreased compared with Example 3; this is because the lack of the synergistic effect of cerium oxide or lanthanum oxide, the microstructure of the high-temperature composite material is deteriorated, the porosity is increased, the sintering process is not sufficient, the brittleness is increased, and the material is prone to stress concentration phenomenon when thermal stress is generated, and is more prone to damage.

[0109] The specific embodiments are only an explanation of the present application, and are not a limitation of the present application. Through the above description, relevant personnel can make various changes and modifications without deviating from the technical idea of the present application. The technical scope of the present application is not limited to the content of the specification, and must be determined according to the scope of the claims.

Claims

1. A high-temperature composite material for a flame synthesis apparatus, characterized in that: The components include the following parts by mass: 50-70 parts of modified ceramic powder 10-20 parts of coupling agent modified zirconium oxide fiber 8-12 parts of oxidized modified carbon fiber 1-3 parts of lanthanum oxide 2-4 parts of cerium oxide; The modified ceramic powder is prepared using the following steps: The ceramic powder is cleaned to obtain pretreated ceramic powder; the pretreated ceramic powder and the release agent are ball-milled and mixed to obtain a mixture; the mixture is nitrided to obtain modified ceramic powder. The ceramic powder includes zirconium boride powder and silicon carbide powder; The mass ratio of zirconium boride powder, silicon carbide powder, and release agent is 1:(0.5-1):0.08; The separating agent includes aluminum oxide and yttrium oxide; The nitriding treatment conditions are: nitriding temperature 900-1100℃, nitriding time 6-8h, nitriding atmosphere is nitrogen and ammonia with a volume ratio of 1:(0.4-0.6), and gas flow rate is 1-3L / min; The raw materials for preparing the coupling agent modified zirconia fiber include zirconia fiber body, hydrofluoric acid and titanate coupling agent. The coupling agent-modified zirconia fiber is prepared using the following steps: Prepare a hydrofluoric acid solution, immerse the zirconia fiber body in the prepared hydrofluoric acid solution and stir. After etching is completed, separate the etched fiber and wash it with water until the pH is neutral to obtain the preliminarily modified zirconia fiber. The titanate coupling agent is mixed with isopropanol to obtain a coupling agent solution; The preliminarily modified zirconia fiber was immersed in a coupling agent solution, heated and stirred during immersion. After immersion, the immersed fiber was separated, washed and dried to obtain coupling agent modified zirconia fiber.

2. The high-temperature composite material for a flame synthesis apparatus according to claim 1, characterized in that: The oxidized modified carbon fiber is prepared using the following steps: Prepare a modified aqueous solution containing hydrogen peroxide and sodium hydroxide. Add carbon fibers to the modified aqueous solution, heat and stir to soak, separate to obtain the modified fibers, wash and dry the modified fibers to obtain oxidized modified fibers.

3. A high-temperature composite material for a flame synthesis apparatus according to any one of claims 1-2, characterized in that: The high-temperature composite material used in the flame synthesis device is prepared using the following steps: Lanthanum oxide and cerium oxide were added to the modified ceramic powder and stirred to obtain a premix; coupling agent modified zirconium oxide fiber and oxide modified carbon fiber were added to the premix and stirred to obtain a mixture; the mixture was placed in a mold and cold isostatically pressed to obtain a green body; the green body was sintered under inert gas protection and cooled in the furnace to obtain a high-temperature composite material for flame synthesis device.

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