Silicon nitride-based composite ceramic material and preparation method thereof

Abstract

The invention belongs to the technical field of engineering ceramic composite materials, and discloses a silicon nitride-based composite ceramic material and a preparation method thereof.The method comprises the following steps that wood is smashed and sieved, and wood powder is obtained; weighing 2%-5% by mass of wood powder, 4%-6% by mass of yttrium oxide powder, 4%-6% by mass of aluminum oxide powder and 85%-88% by mass of silicon nitride powder; uniformly mixing all the powder through a wet grinding method, drying for 3-10 hours at the temperature of 60-100 DEG C, screening to obtain composite powder, and mixing the composite powder for the second time; uniformly mixing the composite powder subjected to secondary mixing, and loading the mixed powder into a mold for pre-pressing; and sintering the pre-pressed composite powder in an environment of 1700 DEG C to obtain the silicon nitride-based composite ceramic material. The wood powder is used as one of the raw materials, leftover materials of wood processing can be fully utilized, and the mechanical property of the prepared silicon nitride-based composite ceramic material is improved.

Description

Technical Field

[0001] This invention belongs to the field of engineering ceramic composite materials technology, specifically relating to a silicon nitride-based composite ceramic material and its preparation method. Background Technology

[0002] Ceramic materials are a class of inorganic non-metallic materials made from natural or synthetic compounds through shaping and high-temperature sintering. Silicon nitride (Si3N4), as an advanced structural ceramic, possesses excellent mechanical, chemical, and physical properties and is widely used in engine components, cutting tools, aerospace, machining, and electronic information fields.

[0003] Chinese patent publication number CN108675797A, entitled "Silicon nitride-based composite ceramic material and its microwave sintering preparation method," describes a silicon nitride-based composite ceramic material comprising, by weight percentage, the following components: α... The composition is: Si3N4 68%–75%, Y2O3 3%–5%, MgO 3%–5%, Al2O3 2%–4%, (W,Ti)C 15%–20%, Ni 1%–4%. This patent application uses silicon carbide wafer-assisted heating to replace the traditional powder-assisted sintering, but it does not make full use of environmentally friendly materials. Summary of the Invention

[0004] In order to overcome the problems existing in the prior art, the present invention aims to provide a silicon nitride-based composite ceramic material and its preparation method. Using wood flour as one of the raw materials, it can make full use of wood processing scraps, reduce material costs, and make full use of waste materials. The preparation process of the present invention is simple, the preparation cycle is short, and the mechanical properties of the prepared silicon nitride-based composite ceramic material are improved.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: In a first aspect, the present invention provides a method for preparing a silicon nitride-based composite ceramic material, comprising the following steps: Wood is crushed and sieved to obtain wood powder; Weigh out 2%–5% wood flour powder, 4%–6% yttrium oxide powder and 4%–6% alumina powder, and 85%–88% silicon nitride powder. After all the powders are mixed evenly by wet milling, they are dried at 60℃-100℃ for 3h-10h, and then sieved to obtain composite powder. The composite powder is then mixed a second time. The composite powder after secondary mixing is mixed evenly and then pre-pressed into a mold. The pre-pressed composite powder was sintered at 1700℃ to obtain silicon nitride-based composite ceramic materials.

[0006] Optionally, the wood powder is pulverized by a high-speed pulverizer and then filtered through a sieve.

[0007] Optionally, the total mass fraction of the yttrium oxide powder and the alumina powder is 10%.

[0008] Optionally, the composite powder is sieved before pre-compression to obtain a composite powder with uniform particles.

[0009] Optionally, the composite powder can be pre-pressed using a static pressure mold.

[0010] Optionally, all the powders that are mixed evenly can be wet-milled using a ball mill before the drying step.

[0011] Optionally, anhydrous ethanol can be used as the grinding medium during wet grinding.

[0012] Optionally, after obtaining the composite powder through the drying step, it is sieved, then the composite powder is mixed a second time using a three-dimensional vibrating mixer, and then a pre-compression step is performed.

[0013] Optionally, in the pre-pressing step, the composite powder is loaded into the mold of the sintering furnace for pre-pressing, and then the mold of the sintering furnace is placed into the sintering furnace for sintering under the protection of nitrogen.

[0014] Secondly, the present invention provides a silicon nitride-based composite ceramic material, which is prepared using the aforementioned method for preparing a silicon nitride-based composite ceramic material.

[0015] Compared with the prior art, the present invention has the following beneficial effects: This invention discloses a method for preparing a silicon nitride-based composite ceramic material, which involves mixing treated wood flour powder with silicon nitride powder and then hot-pressing and sintering the mixture. Silicon nitride, with its high strength, high temperature resistance, corrosion resistance, low density, and excellent thermodynamic properties, can be applied in aerospace, energy, precision manufacturing, metallurgy, chemical engineering, biomedicine, and consumer electronics fields.

[0016] Wood flour, a waste product from wood processing, is a powdery substance obtained through mechanical crushing and grinding. From a chemical composition perspective, its main components are cellulose, hemicellulose, and lignin. Given its wide range of sources, encompassing waste generated from various wood processing scenarios, the method of this invention can further enhance the application value of wood flour waste in numerous fields such as industry, environmental protection, and scientific research.

[0017] Furthermore, this invention obtains raw materials with uniform particle size by sieving the composite material before pre-compression, thus ensuring the dense structure of the novel ceramic composite material obtained by sintering.

[0018] The present invention discloses a silicon nitride-based composite ceramic material, which uses wood flour powder and silicon nitride as the main raw materials. The wood flour powder has a porous structure composed of various cell walls, which are mainly composed of biopolymers, namely carbohydrate polymers of cellulose and hemicellulose and phenolic polymers of lignin. Attached Figure Description

[0019] The accompanying drawings described herein are for illustrative purposes only and are not intended to limit the scope of the invention in any way. Furthermore, the shapes and proportions of the components in the drawings are merely schematic to aid in understanding the invention and do not specifically limit the shapes and proportions of the components. In the drawings: Figure 1 This is a flowchart of the method steps in an embodiment of the present invention; Figure 2 This is an SEM (Scanning Electron Microscope) image of the original silicon nitride powder in an embodiment of the present invention. Detailed Implementation To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0020] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0021] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper", "lower", "horizontal", "inner" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of the invention is usually placed during use, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0022] When an element is referred to as being "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only embodiments. The use of the term "horizontal" does not imply that the component is required to be absolutely horizontal, but rather that it may be slightly tilted. "Horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but rather that it may be slightly tilted.

[0023] It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. In the description of this invention, it should be understood that the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or collections thereof.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in the specification and appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0025] The present invention will now be described in detail with reference to the accompanying drawings.

[0026] like Figure 1 As shown, a method for preparing a silicon nitride-based composite ceramic material according to the present invention includes the following steps: Wood is crushed and sieved to obtain wood powder; Weigh out 2%–5% wood flour powder, 4%–6% yttrium oxide powder and 4%–6% alumina powder, and 85%–88% silicon nitride powder. After all the powders are mixed evenly by wet milling, they are dried at 60℃-100℃ for 3h-10h, and then sieved to obtain composite powder. The composite powder is then mixed a second time. The composite powder after secondary mixing is mixed evenly and then pre-pressed into a mold. The pre-pressed composite powder was sintered at 1700℃ to obtain silicon nitride-based composite ceramic materials.

[0027] The present invention discloses a silicon nitride-based composite ceramic material, which is prepared by the aforementioned method for preparing a silicon nitride-based composite ceramic material.

[0028] In current industrialized manufacturing systems, materials such as lignin, cellulose, and graphene are commonly used to enhance the performance of ceramic materials. While these precursors ensure stable process operation, their drawbacks, including unsustainable resource utilization, environmental pollution, and complex processing requirements, urgently need to be addressed. In stark contrast, renewable biomass such as forestry residues and agricultural byproducts not only offer diverse structures but also significant cost advantages, providing an ideal precursor platform for improving the performance of composite ceramics.

[0029] Existing silicon nitride ceramic preparation processes do not fully utilize inexpensive and environmentally friendly materials, and the preparation cycle is relatively long.

[0030] The method for preparing silicon nitride-based composite ceramic materials of the present invention involves mixing treated wood flour powder with silicon nitride powder and then hot-pressing and sintering the mixture. Silicon nitride, with its high strength, high temperature resistance, corrosion resistance, low density, and excellent thermodynamic properties, has been applied on a large scale in aerospace, energy, precision manufacturing, metallurgy, chemical industry, biomedicine, and consumer electronics fields.

[0031] Wood flour, a waste product from wood processing, is a powdery substance obtained through mechanical crushing and grinding. From a chemical composition perspective, its main components are cellulose, hemicellulose, and lignin. Given its wide range of sources, encompassing waste generated from various wood processing scenarios, the method of this invention can further enhance the application value of wood flour waste in numerous fields such as industry, environmental protection, and scientific research.

[0032] This invention discloses a silicon nitride-based composite ceramic material, using wood flour powder and silicon nitride as the main raw materials. The wood flour powder has a porous structure composed of various cell walls, which are mainly composed of biopolymers, namely carbohydrate polymers of cellulose and hemicellulose and phenolic polymers of lignin. By adding wood flour powder, this invention not only saves materials but also further improves the strength of the silicon nitride-based composite ceramic.

[0033] Example 1 This embodiment describes a method for preparing a silicon nitride-based composite ceramic, which includes the following steps: Step 1: Using an electronic balance (accuracy 0.01 mg), weigh out 4%-6% of alumina powder, 4%-6% of yttrium oxide powder, and 90 wt.% of silicon nitride powder according to the total mass and the designed mass fraction of each substance in the corresponding group. Step 2: Mix the raw powder obtained in Step 2, use anhydrous ethanol as the grinding medium, and perform further wet ball milling in a ball mill. The rotation speed is set to 150 r / min, and the ball milling time is set to 8 h.

[0034] Step 3: Dry using a vacuum drying oven. Pour the slurry obtained after ball milling in Step 2 into a petri dish and dry at 60-100℃ for 3-10 hours to obtain a fully dried composite powder.

[0035] Step 4: The fully dried composite powder is sieved through an 80-mesh screen to obtain composite powder with smaller and more uniform particle size.

[0036] Step 5: The composite powder is mixed a second time using a three-dimensional vibrating mixer. Since the control variable is the change in wood flour content, the sieved composite powder needs to be mixed at 60 r / min for 10 hours to obtain a more uniform composite powder.

[0037] Step 6: The composite powder obtained in step 5 is sintered using a vacuum hot pressing sintering furnace. The composite powder is pre-pressed into the mold of the sintering furnace and sintered under nitrogen protection. The sintering temperature is 1700℃, the pressure is 30MPa, and the holding time is 60min. After the hot pressing sintering is completed, a silicon nitride-based composite ceramic material sample is obtained.

[0038] Example 2 This embodiment describes a method for preparing a silicon nitride-based composite material, which includes the following steps: Step 1: Process the wood to obtain wood powder.

[0039] Step 2: Using an electronic balance (accuracy 0.01 mg), weigh out 4%-6% of alumina powder, 4%-6% of yttrium oxide powder, 2 wt.% of wood flour powder, and 88 wt.% of silicon nitride powder according to the total mass and the designed mass fraction of each substance in the corresponding group. Step 3: Mix the raw powder obtained in Step 2, use anhydrous ethanol as the grinding medium, and perform further wet ball milling in a ball mill. The rotation speed is set to 150 r / min, and the ball milling time is set to 8 h.

[0040] Step 4: Dry using a vacuum drying oven. Pour the slurry obtained after ball milling in Step 3 into a petri dish and dry at 60-100℃ for 3-10 hours to obtain a fully dried composite powder.

[0041] Step 5: The fully dried composite powder is sieved through an 80-mesh screen to obtain composite powder with smaller and more uniform particle size.

[0042] Step 6: The composite powder is mixed a second time using a three-dimensional vibrating mixer. Because the density of wood flour powder is much lower than that of silicon nitride powder, it will separate due to gravity during sieving. Therefore, the sieved composite powder needs to be mixed at 60 r / min for 10 hours to obtain a more uniform composite powder.

[0043] Step 7: The composite powder obtained in step 6 is sintered using a vacuum hot pressing sintering furnace. The composite powder is pre-pressed into the mold of the sintering furnace and sintered under nitrogen protection. The sintering temperature is 1700℃, the pressure is 30MPa, and the holding time is 60min. After the hot pressing sintering is completed, a silicon nitride-based composite ceramic material sample is obtained.

[0044] Example 3 This embodiment describes a method for preparing a silicon nitride-based composite ceramic material, including the following steps: Step 1: The wood is subjected to high-speed pulverization to obtain wood powder.

[0045] Step 2: Using an electronic balance (accuracy 0.01 mg), weigh out 4%-6% of alumina powder, 4%-6% of yttrium oxide powder, 3 wt.% of wood flour powder, and 87 wt.% of silicon nitride powder according to the total mass and the designed mass fraction of each substance in the corresponding group. Step 3: Mix the raw powder obtained in Step 2 with anhydrous ethanol and perform wet milling. Set the rotation speed to 150 r / min and the ball milling time to 8 h.

[0046] Step 4: Dry the mixed slurry obtained in step 3 using a vacuum drying oven to obtain a dried mixed powder.

[0047] Step 5: After the powder in Step 4 is fully dried, it is sieved through an 80-mesh screen to obtain a composite powder with smaller and more uniform particle size. The obtained composite powder is then mixed a second time.

[0048] Step 6: The composite powder obtained in step 5 is loaded into a graphite mold and sintered under nitrogen protection. The sintering temperature is 1700℃, the pressure is 30MPa, and the holding time is 60min. After hot pressing and sintering, a silicon nitride-based composite ceramic material sample is obtained.

[0049] Step 7: Take SEM images of the powder sample used in Step 5 (see attached image). Figure 1 Observation and analysis show that the wood flour and silicon nitride particles are mixed evenly.

[0050] Example 4 This embodiment describes a method for preparing a silicon nitride-based composite ceramic material, including the following steps: Step 1: The wood is subjected to high-speed pulverization to obtain wood powder.

[0051] Step 2: Using an electronic balance (accuracy 0.01 mg), weigh out 4%-6% of alumina powder, 4%-6% of yttrium oxide powder, 4 wt.% of wood flour powder, and 86 wt.% of silicon nitride powder according to the total mass and the designed mass fraction of each substance in the corresponding group. Step 3: Mix the raw powder obtained in Step 2 with anhydrous ethanol and perform wet milling. Set the rotation speed to 150 r / min and the ball milling time to 8 h.

[0052] Step 4: Dry the mixed slurry obtained in step 3 using a vacuum drying oven to obtain a dried mixed powder.

[0053] Step 5: After the powder in Step 4 is fully dried, it is sieved through an 80-mesh screen to obtain a composite powder with smaller and more uniform particle size. The obtained composite powder is then mixed a second time.

[0054] Step 6: The composite powder obtained in step 5 is loaded into a graphite mold and sintered under nitrogen protection. The sintering temperature is 1700℃, the pressure is 30MPa, and the holding time is 60min. After hot pressing and sintering, a silicon nitride-based composite ceramic material sample is obtained.

[0055] Example 5 This embodiment describes a method for preparing a silicon nitride-based composite ceramic material, including the following steps: Step 1: The wood is subjected to high-speed pulverization to obtain wood powder.

[0056] Step 2: Using an electronic balance (accuracy 0.01 mg), weigh out 4%-6% of alumina powder, 4%-6% of yttrium oxide powder, 5 wt.% of wood flour powder, and 85 wt.% of silicon nitride powder according to the total mass and the designed mass fraction of each substance in the corresponding group.

[0057] Step 3: Mix the raw powder obtained in Step 2 with anhydrous ethanol and perform wet milling. Set the rotation speed to 150 r / min and the ball milling time to 8 h.

[0058] Step 4: Dry the mixed slurry obtained in step 3 using a vacuum drying oven to obtain a dried mixed powder.

[0059] Step 5: After the powder in Step 4 is fully dried, it is sieved through an 80-mesh screen to obtain a composite powder with smaller and more uniform particle size. The obtained composite powder is then mixed a second time.

[0060] Step 6: The composite powder obtained in step 5 is loaded into a graphite mold and sintered under nitrogen protection. The sintering temperature is 1700℃, the pressure is 30MPa, and the holding time is 60min. After hot pressing and sintering, a silicon nitride-based composite ceramic material sample is obtained.

[0061] The silicon nitride-based composite ceramics prepared in Example 1 and those prepared in Examples 2-5 were subjected to physical and mechanical property tests to obtain the effect of different contents of wood flour powder on the mechanical properties of silicon nitride-based composite ceramic materials, as shown in Table 1.

[0062] Table 1

[0063] As shown in Table 1, when the wood powder content is 2%, compared with the wood powder content of 0%, the fracture toughness of the silicon nitride-based composite ceramic material decreases from 5.35±0.22MPa·m½ to 3.36±0.24MPa·m½, but its flexural strength increases from 691.408±20.74MPa to 765.85±18.42MPa.

[0064] With the addition of wood flour, when the wood flour content is 3%, the fracture toughness and flexural strength of the silicon nitride-based composite ceramic material are improved. The fracture toughness reaches 6.05±0.85 MPa·m½, and the flexural strength reaches 753.24±28.33 MPa. Furthermore, the silicon nitride-based composite ceramic material also exhibits excellent density and hardness at this level. Compared to materials without wood flour, its overall performance is enhanced. However, when the wood flour content is 4% and 5%, the excessive wood flour content in the silicon nitride composite ceramic material leads to agglomeration of the wood flour, negatively impacting the material and causing a decrease in mechanical properties.

[0065] Unless otherwise specified, the equipment components involved in the above embodiments are all conventional equipment components, and the structural settings, working methods or control methods involved are all conventional settings, working methods or control methods in the art unless otherwise specified.

[0066] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Any other modifications or equivalent substitutions made by those skilled in the art to the technical solutions of the present invention, as long as they do not depart from the spirit and scope of the technical solutions of the present invention, should be covered within the scope of the claims of the present invention.

Claims

1. A method for preparing a silicon nitride-based composite ceramic material, characterized in that, Includes the following steps: Wood is crushed and sieved to obtain wood powder; Weigh out 2%–5% wood flour powder, 4%–6% yttrium oxide powder and 4%–6% alumina powder, and 85%–88% silicon nitride powder. After all the powders are mixed evenly by wet milling, they are dried at 60℃-100℃ for 3h-10h, and then sieved to obtain composite powder. The composite powder is then mixed a second time. The composite powder after secondary mixing is mixed evenly and then pre-pressed into a mold. The pre-pressed composite powder was sintered at 1700℃ to obtain silicon nitride-based composite ceramic materials.

2. The method for preparing a silicon nitride-based composite ceramic material according to claim 1, characterized in that, The wood flour powder is obtained by pulverizing it with a high-speed pulverizer and filtering it through a sieve.

3. The method for preparing a silicon nitride-based composite ceramic material according to claim 1, characterized in that, The total mass fraction of the yttrium oxide powder and aluminum oxide powder is 10%.

4. The method for preparing a silicon nitride-based composite ceramic material according to claim 1, characterized in that, Before pre-compression, the composite powder is sieved to obtain composite powder with uniform particles.

5. The method for preparing a silicon nitride-based composite ceramic material according to claim 1, characterized in that, The composite powder is pre-pressed using a static pressure mold.

6. The method for preparing a silicon nitride-based composite ceramic material according to claim 1, characterized in that, Before the drying step, all the powders that are mixed evenly are wet-milled using a ball mill.

7. The method for preparing a silicon nitride-based composite ceramic material according to claim 6, characterized in that, When wet grinding, anhydrous ethanol is used as the grinding medium.

8. The method for preparing a silicon nitride-based composite ceramic material according to claim 1, characterized in that, After obtaining the composite powder through the drying step, it is sieved, then the composite powder is mixed a second time using a three-dimensional vibrating mixer, and then pre-compressed.

9. The method for preparing a silicon nitride-based composite ceramic material according to claim 1, characterized in that, In the pre-pressing step, the composite powder is loaded into the mold of the sintering furnace for pre-pressing, and then the mold of the sintering furnace is placed into the sintering furnace for sintering under the protection of nitrogen.

10. A silicon nitride-based composite ceramic material, characterized in that, The silicon nitride-based composite ceramic material is prepared using the preparation method described in any one of claims 1 to 9.

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