Preparation method and product of 3D printing lignocellulose derived silicon carbide ceramic
阅读说明：本技术 3d打印木质纤维素衍生碳化硅陶瓷的制备方法及产品 (Preparation method and product of 3D printing lignocellulose derived silicon carbide ceramic ) 是由 闫春泽 王长顺 吴思琪 李昭青 陈安南 史玉升 于 2021-09-07 设计创作，主要内容包括：本发明属于碳化硅陶瓷材料相关技术领域,其公开了一种3D打印木质纤维素衍生碳化硅陶瓷的制备方法及产品,方法包括：将木质纤维素粉材采用真空搅拌消泡技术获得木质纤维素浆料或采用喷雾造粒技术获得木质纤维素造粒粉；将木质纤维素浆料或木质纤维素造粒粉采用3D打印技术获得木质纤维素/树脂坯体；将木质纤维素/树脂坯体气氛热解获得生物质碳预制体；将生物质碳预制体进行熔融硅反应而后进行增密处理获得碳化硅陶瓷。通过本发明可制备复杂结构的木质纤维素衍生碳化硅陶瓷,由此实现了生物质材料的绿色3D打印,解决了碳化硅陶瓷机械切削加工困难的问题,且碳化硅陶瓷制品中没有残硅和残碳,在高温条件下具有显著优势。(The invention belongs to the technical field of silicon carbide ceramic materials, and discloses a preparation method and a product of 3D printing lignocellulose derived silicon carbide ceramic, wherein the method comprises the following steps: the lignocellulose powder is subjected to vacuum stirring defoaming technology to obtain lignocellulose pulp or spray granulation technology to obtain lignocellulose granulation powder; obtaining a lignocellulose/resin green body from lignocellulose pulp or lignocellulose granulation powder by adopting a 3D printing technology; pyrolyzing a lignocellulose/resin green body in an atmosphere to obtain a biomass carbon preform; and carrying out fused silicon reaction on the biomass carbon preform, and then carrying out densification treatment to obtain the silicon carbide ceramic. The lignocellulose-derived silicon carbide ceramic with a complex structure can be prepared by the method, so that green 3D printing of the biomass material is realized, the problem of difficulty in mechanical cutting processing of the silicon carbide ceramic is solved, and the silicon carbide ceramic product has no residual silicon and carbon and has remarkable advantages under a high-temperature condition.)
1. A method for preparing 3D printed lignocellulose derived silicon carbide ceramic, the method comprising:
s1: the lignocellulose powder is subjected to vacuum stirring defoaming technology to obtain lignocellulose pulp or spray granulation technology to obtain lignocellulose granulation powder;
s2: obtaining a lignocellulose/resin green body from the lignocellulose pulp or the lignocellulose granulated powder by adopting a 3D printing technology;
s3: pyrolyzing the lignocellulose/resin green body in an atmosphere to obtain a biomass carbon preform;
s4: and carrying out molten silicon reaction on the biomass carbon preform, and then carrying out densification treatment to obtain the silicon carbide ceramic.
2. The method according to claim 1, wherein the length of the lignocellulosic powder is 50 to 125 μm, the aspect ratio is 28 to 100, and the particle size of the lignocellulosic granulated powder is 20 to 70 μm.
3. The method according to claim 1, wherein the bulk density of the lignocellulosic granulated powder is 0.5 to 0.7g/cm3The angle of repose is 0 to 40 degrees.
4. The method of claim 1, wherein the step of obtaining the lignocellulosic granulated powder by using the spray granulation technique in step S1 comprises:
dissolving phenolic resin in an organic solvent to obtain a mixed solution;
adding the lignocellulose powder into the mixed solution, mixing and stirring, wherein the volume ratio of the lignocellulose powder to the mixed solution is (1-2) to (1-2);
obtaining lignocellulose granulation powder by adopting a closed cycle spray granulation technology, wherein the technological parameters of the closed cycle spray granulation technology are as follows: the inlet temperature of the hot air is 85-125 ℃, the outlet temperature is 80-85 ℃, the rotation speed of the atomizer is 8000-12000 r/min, and the nitrogen flow rate is 100-200 ml/min.
5. The method of claim 1, wherein step S4, after the reacting the molten silicon, further comprises evacuating the reacted product at a temperature of not less than 2000 ℃ to remove residual silicon, and introducing air into the reacted product at a temperature of less than 1000 ℃ to remove residual carbon.
6. The method according to claim 3, wherein the phenolic resin is a thermosetting phenolic resin, and the organic solvent is one or more of methanol, absolute ethanol or acetone.
7. The method of claim 1, wherein the biomass carbon preform has a porosity of 55% to 65%.
8. The method according to claim 1, wherein the porosity of the product after the molten silicon reaction in step S4 is 10-30%.
9. The method of claim 1 or 8, wherein the step of reacting the molten silicon is:
embedding the biomass carbon preform by using coarse silicon particles, wherein the particle size of the coarse silicon particles is 1-5 mm, and the mass of the coarse silicon particles is 2.5-3 times that of the biomass carbon preform;
under the condition of a vacuum environment, the temperature is raised to 1450-1800 ℃ at the rate of 5-10 ℃/min, and then the reaction is carried out at 1450-1800 ℃ for 0.5-1.5 h.
10. A silicon carbide ceramic prepared by the method for preparing a 3D printed lignocellulose derived silicon carbide ceramic according to any one of claims 1 to 9.
Technical Field
The invention belongs to the technical field of silicon carbide ceramic materials, and particularly relates to a preparation method and a product of 3D printing lignocellulose derived silicon carbide ceramic.
Background
The silicon carbide ceramic is an engineering material with wide application, and is suitable for extreme conditions of high corrosion, high temperature, high mechanical load and the like. Due to the inherent high hardness and brittleness of the material, the traditional processing methods of silicon carbide ceramics such as extrusion, die pressing, mechanical grinding and the like have high cost and high rejection rate, and are difficult to process silicon carbide ceramic parts with complex structures. The 3D printing process can form a silicon carbide ceramic blank with high precision and a complex structure, and the silicon carbide ceramic component is formed by subsequent sintering and near net forming, and meanwhile, the processing cost can be greatly reduced.
Lignocellulose is an organic flocculent fiber material obtained by chemical treatment and mechanical processing of natural wood, the yield is rich, and the cost of raw materials is low. However, lignocellulose has a large specific surface area and a low bulk density, and can be processed into a powder material suitable for 3D printing and forming by mechanical chopping and granulation.
For example, chinese patent CN2016104968932 discloses a method for preparing a C/C-SiC composite part and a product thereof, wherein a solvent evaporation method is used to prepare phenolic-coated carbon fiber powder, and a 3D printing process is used to form a SiC composite material with a complex structure, but the powder preparation efficiency is low, and molten silicon reacts with carbon fibers during a reaction sintering process to reduce the toughening effect thereof. Chinese patent CN201910599122.X discloses a preparation method of porous silicon carbide wood ceramic based on a cellulose aerogel template, wherein cellulose aerogel is used as the template, and the high porosity characteristic of the cellulose aerogel is more beneficial to the precursor solution to be more easily and fully impregnated, but a blank obtained by the method has high shrinkage and is easy to crack in the cracking process, so that the performance of silicon carbide products is influenced.
Disclosure of Invention
Aiming at the defects or improvement requirements of the prior art, the invention provides a preparation method and a product of 3D printing lignocellulose derived silicon carbide ceramic, which can realize the preparation of the lignocellulose derived silicon carbide ceramic with a complex structure, thereby realizing the green 3D printing of biomass materials, solving the problem of difficult mechanical cutting processing of the silicon carbide ceramic, and the silicon carbide ceramic product has no residual silicon and carbon and has remarkable advantages under high temperature conditions.
To achieve the above object, according to one aspect of the present invention, there is provided a method for preparing a 3D printed lignocellulose-derived silicon carbide ceramic, the method comprising: s1: the lignocellulose powder is subjected to vacuum stirring defoaming technology to obtain lignocellulose pulp or spray granulation technology to obtain lignocellulose granulation powder; s2: obtaining a lignocellulose/resin green body from the lignocellulose pulp or the lignocellulose granulated powder by adopting a 3D printing technology; s3: pyrolyzing the lignocellulose/resin green body in an atmosphere to obtain a biomass carbon preform; s4: and carrying out molten silicon reaction on the biomass carbon preform, and then carrying out densification treatment to obtain the silicon carbide ceramic.
Preferably, the length of the lignocellulose powder is 50-125 micrometers, the length-diameter ratio is 28-100, and the particle size of the lignocellulose granulated powder is 20-70 micrometers.
Preferably, the loose packed density of the lignocellulose granulated powder is 0.5-0.7 g/cm3The angle of repose is 0 to 40 degrees.
Preferably, the step of obtaining the lignocellulose granulated powder by adopting the spray granulation technology in the step S1 comprises the following steps: dissolving phenolic resin in an organic solvent to obtain a mixed solution; adding the lignocellulose powder into the mixed solution, mixing and stirring, wherein the volume ratio of the lignocellulose powder to the mixed solution is (1-2) to (1-2); obtaining lignocellulose granulation powder by adopting a closed cycle spray granulation technology, wherein the technological parameters of the closed cycle spray granulation technology are as follows: the inlet temperature of the hot air is 85-125 ℃, the outlet temperature is 80-85 ℃, the rotation speed of the atomizer is 8000-12000 r/min, and the nitrogen flow rate is 100-200 ml/min.
Preferably, the phenolic resin is thermosetting phenolic resin, and the organic solvent is one or more of methanol, absolute ethyl alcohol or acetone.
Preferably, the atmosphere pyrolysis is specifically: under the protection of inert gas, the temperature is raised to 800-1000 ℃ at the heating rate of 0.5-1 ℃/min, and then the temperature is maintained for 2-3 h.
Preferably, the porosity of the biomass carbon preform is 55% to 65%.
Preferably, the step S4, after the reaction of the molten silicon, further includes evacuating the product after the reaction of the molten silicon at a temperature not less than 2000 ℃ to remove residual silicon, and introducing air into the product at a temperature below 1000 ℃ to remove residual carbon.
Preferably, in step S4, the porosity of the product after the molten silicon reaction is 10 to 30%.
Preferably, in step S4, the molten silicon is reacted by: embedding the biomass carbon preform by using coarse silicon particles, wherein the particle size of the coarse silicon particles is 1-5 mm, and the mass of the coarse silicon particles is 2.5-3 times that of the biomass carbon preform; under the condition of a vacuum environment, the temperature is raised to 1450-1800 ℃ at the rate of 5-10 ℃/min, and then the reaction is carried out at 1450-1800 ℃ for 0.5-1.5 h.
Preferably, in step S4, a ceramic precursor impregnation cracking technique is used to perform densification; further preferably, the vacuum stirring defoaming rotating speed is 1000-2000 r/min, the time is 5-20 min, and the vacuum degree is 0-102Pa。
According to another aspect of the invention, a silicon carbide ceramic prepared by the preparation method of the 3D printing lignocellulose derived silicon carbide ceramic is provided.
In general, compared with the prior art, the preparation method and the product of the 3D printed lignocellulose derived silicon carbide ceramic provided by the invention have the following beneficial effects:
1. this application adopts lignocellulose to be the powder that 3D printed for raw materials preparation, and then satisfy the preparation of the lignocellulose derived silicon carbide ceramic of complex structure, lignocellulose powder can not destroy three-dimensional crosslinked structure wherein after vacuum stirring defoaming technique or spray granulation technical treatment, can remain original biological form after 3D prints, guarantee considerable porosity, abundant fused silicon infiltration passageway and reaction space have been provided for the fused silicon reaction, be favorable to going on smoothly of reaction, make the carbon silicon reaction more abundant, and then obtain the even excellent silicon carbide ceramic product of performance.
2. The product after the molten silicon reaction is vacuumized at the temperature of not less than 2000 ℃ so that the silicon is changed into gaseous silicon to be removed, and air is introduced into the product at the temperature of below 1000 ℃ so that carbon can be converted into carbon dioxide to be removed, so that the treated product has no residual silicon and carbon, and the performance is more excellent.
3. The pyrolysis of the lignocellulose/resin green body atmosphere can convert organic matter into carbon, which facilitates subsequent reaction with molten silicon.
4. The porosity of the biomass carbon preform is 55-65%, the liquid silicon can be ensured to be fully contacted with carbon in the molten silicon reaction process in the range, too high porosity can reduce the strength of the biomass carbon preform, and too low porosity is not beneficial to full contact reaction of the liquid silicon and the carbon.
5. The particle size and morphology of the particles obtained by the spray granulation technology are very suitable for 3D printing and the efficiency is high.
6. The bulk density and the angle of repose of the particles obtained by adopting the spray granulation technology are in a proper interval, and the 3D printing formability is good, so that the internal structure of a workpiece is uniform, and the strength is high.
7. The method has the advantages that the lignocellulose is used as the raw material to prepare the powder suitable for 3D printing, and the silicon carbide green body is formed by adopting various 3D printing processes, so that the raw material cost is reduced, the application range of the lignocellulose is expanded, the additional value of the lignocellulose is improved, the lignocellulose can be obtained by deep processing of wood wastes, and the ecological civilization concept is met; meanwhile, the method expands the range of 3D printing materials, is simple in process and strong in feasibility, can form high-performance silicon carbide ceramics with complex structures, and has deep research value.
Drawings
Fig. 1 is a step diagram of a method of making a 3D printed lignocellulose-derived silicon carbide ceramic of the present example;
fig. 2 is a flow chart of a method of making the 3D printed lignocellulose-derived silicon carbide ceramic of this embodiment.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
Referring to fig. 1 and 2, the present invention provides a method for preparing a 3D printed lignocellulose-derived silicon carbide ceramic, including the following steps S1 to S4.
S1: the lignocellulose powder is subjected to vacuum stirring defoaming technology to obtain lignocellulose pulp or spray granulation technology to obtain lignocellulose granulation powder.
The length of the lignocellulose powder is preferably 50-125 micrometers, the length-diameter ratio is preferably 28-100, and the particle size of the lignocellulose granulated powder is preferably 20-70 micrometers. The bulk density of the lignocellulose granulated powder is 0.5-0.7 g/cm3The angle of repose is 0 to 40 degrees.
The lignocellulose powder can be obtained by adopting a mechanical short-cutting mode, for example, the lignocellulose with the length of 200-500 micrometers and the length-diameter ratio of 28-100 is mechanically short-cut into the lignocellulose powder with the length of 50-125 micrometers and the length-diameter ratio of 28-100.
If vacuum stirring defoaming technology is adoptedObtaining lignocellulose pulp by the method, wherein the vacuum stirring defoaming rotating speed is 1000-2000 r/min, the time is preferably 5-20 min, and the vacuum degree is preferably 0-102Pa。
The spray granulation technology is preferably a closed cycle spray granulation technology, and the method comprises the following specific steps:
dissolving phenolic resin in an organic solvent to obtain a mixed solution, wherein the phenolic resin is preferably thermosetting phenolic resin, the organic solvent is one or more of methanol, absolute ethyl alcohol or acetone, and for example, the thermosetting phenolic resin and the absolute ethyl alcohol are mixed in a mass ratio of 1: 2 to obtain the mixed solution;
adding the lignocellulose powder into the mixed solution, mixing and stirring, wherein the volume ratio of the lignocellulose powder to the mixed solution is (1-2) to (1-2);
obtaining lignocellulose granulation powder by adopting a closed cycle spray granulation technology, wherein the technological parameters of the closed cycle spray granulation technology are as follows: the inlet temperature of the hot air is 85-125 ℃, the outlet temperature is 80-85 ℃, the rotation speed of the atomizer is 8000-12000 r/min, and the nitrogen flow rate is 100-200 ml/min. The particle size of the lignocellulose granulation powder is 20-70 microns.
S2: and (3) obtaining the lignocellulose/resin green body by adopting the lignocellulose pulp or the lignocellulose granulated powder through a 3D printing technology.
The lignocellulosic pulp 3D printing is preferably Digital Light Processing (DLP), ink direct write forming (DIW), and Stereolithography (SL)
The 3D printing technology of the lignocellulose granulated powder is preferably Selective Laser Sintering (SLS) and three-dimensional spray printing (3 DP).
S3: and pyrolyzing the lignocellulose/resin green body in an atmosphere to obtain a biomass carbon preform.
The atmosphere pyrolysis specifically comprises the following steps:
under the protection of inert gas, the temperature is raised to 800-1000 ℃ at the heating rate of 0.5-1 ℃/min, and then the temperature is maintained for 2-3 h, wherein the inert gas is preferably argon.
The porosity of the biomass carbon preform is 55-65%.
S4: and carrying out molten silicon reaction on the biomass carbon preform, and then carrying out densification treatment to obtain the silicon carbide ceramic.
The molten silicon is reacted by the steps of:
embedding the biomass carbon preform by using coarse silicon particles, wherein the particle size of the coarse silicon particles is 1-5 mm, and the mass of the coarse silicon particles is 2.5-3 times that of the biomass carbon preform;
under the condition of a vacuum environment, the temperature is raised to 1450-1800 ℃ at the rate of 5-10 ℃/min, and then the reaction is carried out at 1450-1800 ℃ for 0.5-1.5 h.
The porosity of the product after the molten silicon reaction is 10-30%.
After the molten silicon reacts, the product after the molten silicon reacts is vacuumized at the temperature of not less than 2000 ℃ to remove residual silicon, and air is introduced into the product at the temperature of below 1000 ℃ to remove residual carbon.
In this embodiment, a ceramic precursor impregnation cracking technology (PIP) is preferably adopted for densification, and the specific steps are as follows:
vacuum impregnation of a liquid polycarbosilane precursor is carried out on a product obtained after reaction of molten silicon, the vacuum impregnation time is 0.5h, then the silicon carbide ceramic impregnated with the liquid polycarbosilane is solidified, the solidification temperature is 180 ℃, the solidification time is 2h, finally the solidified silicon carbide ceramic/polycarbosilane is cracked under a protective atmosphere, the flow rate of the protective atmosphere is preferably 100ml/min, the cracking temperature is preferably 1000-1400 ℃, and the cracking time is preferably 2-5 h. The finally prepared silicon carbide ceramic can keep a three-dimensional cross-linked structure of lignocellulose on the microscopic scale, does not contain carbon residue and silicon residue, and has the characteristics of a complex structure of 3D printing on the macroscopic scale.
Example 1
(a) Mechanically chopping lignocellulose to a certain length to obtain lignocellulose powder, wherein the length of the lignocellulose powder after mechanical chopping is 50 microns, and the length-diameter ratio is 7;
(b) carrying out vacuum stirring defoaming on the lignocellulose powder to obtain lignocellulose pulp, wherein the vacuum stirring defoaming rotating speed is set to be 1000r/min, the time is set to be 20min, and the vacuum degree is set to be 0 Pa;
(c) slicing the wood fiber into pieces according to the designed digital three-dimensional model, and forming a lignocellulose/resin blank by using a digital light treatment process;
(d) placing the lignocellulose/resin green body in an alumina crucible with silicon carbide coarse powder spread at the bottom, setting the heating rate to be 0.5 ℃/min, the pyrolysis temperature to be 800 ℃, and the pyrolysis time to be 3h, and obtaining a lignocellulose carbon preform after pyrolysis;
(e) placing the lignocellulose carbon preform in a graphite crucible, embedding the lignocellulose carbon preform by coarse silicon particles, wherein the particle size of the coarse silicon particles is 1mm, the mass of the coarse silicon particles is 2.5 times of that of a lignocellulose carbon blank, the reaction temperature rise rate is 5 ℃/min, the reaction temperature of molten silicon is 1450 ℃, nitrogen is introduced for protection before the temperature reaches 1450 ℃, vacuumizing is performed when the temperature reaches 1450 ℃, the reaction time of the molten silicon is 1.5h under the vacuum condition, the temperature is raised to 2000 ℃ after the reaction is finished, residual silicon is removed, when the temperature is reduced to below 1000 ℃, nitrogen is removed, air is introduced, residual carbon is removed, and porous silicon carbide ceramic is obtained;
(d) and (2) carrying out vacuum impregnation on the porous silicon carbide ceramic for 0.5h, then curing the porous silicon carbide ceramic, setting the curing temperature to be 180 ℃ and the curing time to be 2h, finally cracking the cured silicon carbide ceramic/polycarbosilane in a protective atmosphere, setting the flow rate of the protective atmosphere to be 100ml/min, setting the cracking temperature to be 1000 ℃, and setting the cracking time to be 5h, thus obtaining the densified silicon carbide ceramic.
Example 2
(a) Mechanically chopping lignocellulose to a certain length to obtain lignocellulose powder, wherein the length of the lignocellulose powder after mechanical chopping is 90 microns, and the length-diameter ratio is 15;
(b) carrying out vacuum stirring defoaming on the lignocellulose powder to obtain lignocellulose pulp, wherein the vacuum stirring defoaming rotating speed is set to 2000r/min, the time is set to 5min, and the vacuum degree is preferably 102 Pa;
(c) slicing the wood fiber into pieces according to the designed digital three-dimensional model, and forming a lignocellulose/resin blank by using an ink direct writing process;
(d) placing the lignocellulose/resin green body in an alumina crucible with silicon carbide coarse powder laid at the bottom, setting the heating rate to be 0.5 ℃/min, the pyrolysis temperature to be 1000 ℃, and the pyrolysis time to be 2h, and obtaining a lignocellulose carbon preform after pyrolysis;
(e) placing the lignocellulose carbon preform in a graphite crucible with the surface coated with a boron nitride coating, embedding the lignocellulose carbon preform by using coarse silicon particles, wherein the particle size of the coarse silicon particles is 3mm, the mass of the coarse silicon particles is 3 times of that of a lignocellulose carbon blank, the reaction temperature rise rate is 5 ℃/min, the reaction temperature of molten silicon is 1650 ℃, nitrogen is introduced for protection before the temperature reaches 1650 ℃, vacuumizing is carried out when the temperature reaches 1650 ℃, the reaction time of the molten silicon under the vacuum condition is 0.5h, after the reaction is finished, the temperature is raised to 2000 ℃, residual silicon is removed, when the temperature is reduced to below 1000 ℃, nitrogen is removed, air is introduced, the residual carbon is removed, and the porous silicon carbide ceramic is obtained;
(d) and (2) carrying out vacuum impregnation on the porous silicon carbide ceramic for 0.5h, then curing the porous silicon carbide ceramic, wherein the curing temperature is set to 180 ℃, the curing time is set to 2h, finally cracking the cured silicon carbide ceramic/polycarbosilane in a protective atmosphere, the flow rate of the protective atmosphere is set to 100ml/min, the cracking temperature is set to 1200 ℃, and the cracking time is preferably 3h, so that the densified silicon carbide ceramic is obtained.
Example 3
(a) Mechanically chopping lignocellulose to a certain length to obtain lignocellulose powder, wherein the length of the lignocellulose powder after mechanical chopping is 90 microns, and the length-diameter ratio is 15;
(b) carrying out vacuum stirring defoaming on the lignocellulose powder to obtain lignocellulose pulp, wherein the vacuum stirring defoaming rotating speed is set to be 1000r/min, the time is set to be 20min, and the vacuum degree is 10 Pa;
(c) slicing the wood fiber into pieces according to the designed digital three-dimensional model, and forming a lignocellulose/resin blank by using an ink direct writing process;
(d) placing the lignocellulose/resin green body in an alumina crucible with silicon carbide coarse powder laid at the bottom, setting the heating rate to be 0.5 ℃/min, the pyrolysis temperature to be 800 ℃, and the pyrolysis time to be 2h, and obtaining a lignocellulose carbon preform after pyrolysis;
(e) placing the lignocellulose carbon preform in a graphite crucible, embedding the lignocellulose carbon preform by coarse silicon particles, wherein the particle size of the coarse silicon particles is 3mm, the mass of the coarse silicon particles is 3 times of that of a lignocellulose carbon blank, the reaction temperature rise rate is 5 ℃/min, the reaction temperature of molten silicon is 1650 ℃, nitrogen is introduced for protection before the temperature reaches 1650 ℃, vacuumizing is performed when the temperature reaches 1650 ℃, the reaction time of the molten silicon is 1h under the vacuum condition, the temperature is raised to 2000 ℃ after the reaction is finished, residual silicon is removed, and when the temperature is reduced to below 1000 ℃, nitrogen is removed, air is introduced, residual carbon is removed, and the porous silicon carbide ceramic is obtained;
(f) and (2) carrying out vacuum impregnation on the porous silicon carbide ceramic for 0.5h, then curing the porous silicon carbide ceramic, wherein the curing temperature is set to 180 ℃, the curing time is set to 2h, finally cracking the cured silicon carbide ceramic/polycarbosilane in a protective atmosphere, the flow rate of the protective atmosphere is set to 100ml/min, the cracking temperature is set to 1400 ℃, and the cracking time is 2h, thus obtaining the densified silicon carbide ceramic.
Example 4
(a) Mechanically chopping lignocellulose to a certain length to obtain lignocellulose powder, wherein the length of the lignocellulose powder after mechanical chopping is 90 microns, and the length-diameter ratio is 15;
(b) carrying out vacuum stirring defoaming on the lignocellulose powder to obtain lignocellulose pulp, wherein the vacuum stirring defoaming rotating speed is set to be 1000r/min, the time is set to be 20min, and the vacuum degree is 102 Pa;
(c) slicing the wood fiber into pieces according to the designed digital three-dimensional model, and forming a lignocellulose/resin blank by using an ink direct writing process;
(d) placing the lignocellulose/resin green body in an alumina crucible with silicon carbide coarse powder laid at the bottom, setting the heating rate to be 0.5 ℃/min, the pyrolysis temperature to be 800 ℃, and the pyrolysis time to be 2h, and obtaining a lignocellulose carbon preform after pyrolysis;
(e) placing the lignocellulose carbon preform in a graphite crucible, embedding the lignocellulose carbon preform by coarse silicon particles, wherein the particle size of the coarse silicon particles is 3mm, the mass of the coarse silicon particles is 3 times of that of a lignocellulose carbon blank, the reaction temperature rise rate is 5 ℃/min, the reaction temperature of molten silicon is 1650 ℃, nitrogen is introduced for protection before the temperature reaches 1650 ℃, vacuumizing is performed when the temperature reaches 1650 ℃, the reaction time of the molten silicon is 1h under the vacuum condition, the temperature is raised to 2000 ℃ after the reaction is finished, residual silicon is removed, and when the temperature is reduced to below 1000 ℃, nitrogen is removed, air is introduced, residual carbon is removed, and the porous silicon carbide ceramic is obtained;
(f) and (2) carrying out vacuum impregnation on the porous silicon carbide ceramic for 0.5h, then curing the porous silicon carbide ceramic, wherein the curing temperature is set to 180 ℃, the curing time is set to 2h, finally cracking the cured silicon carbide ceramic/polycarbosilane in a protective atmosphere, the flow rate of the protective atmosphere is set to 100ml/min, the cracking temperature is set to 1400 ℃, and the cracking time is 2h, thus obtaining the densified silicon carbide ceramic.
Example 5
(a) Mechanically chopping lignocellulose to a certain length to obtain lignocellulose powder, wherein the length of the lignocellulose powder after mechanical chopping is 125 microns, and the length-diameter ratio is 25;
(b) carrying out vacuum stirring defoaming on the lignocellulose powder to obtain lignocellulose pulp, wherein the rotating speed of the vacuum stirring defoaming is set to be 1500r/min, the time is set to be 20min, and the vacuum degree is 0 Pa;
(c) slicing the wood fiber into pieces according to the designed digital three-dimensional model, and forming a lignocellulose/resin blank by utilizing a three-dimensional photocuring process;
(d) placing the lignocellulose/resin green body in an alumina crucible with silicon carbide coarse powder laid at the bottom, setting the heating rate to be 0.5 ℃/min, the pyrolysis temperature to be 800 ℃, and the pyrolysis time to be 2h, and obtaining a lignocellulose carbon preform after pyrolysis;
(e) placing the lignocellulose carbon preform in a graphite crucible, embedding the lignocellulose carbon preform by coarse silicon particles, wherein the particle size of the coarse silicon particles is 5mm, the mass of the coarse silicon particles is 3 times of that of a lignocellulose carbon blank, the reaction temperature rise rate is 5 ℃/min, the reaction temperature of molten silicon is 1800 ℃, nitrogen is introduced for protection before the temperature reaches 1800 ℃, vacuumizing is performed when the temperature reaches 1800 ℃, the reaction time of the molten silicon is 0.5h under the vacuum condition, the temperature is raised to 2000 ℃ after the reaction is finished, residual silicon is removed, when the temperature is reduced to below 1000 ℃, nitrogen is removed, air is introduced, residual carbon is removed, and porous silicon carbide ceramic is obtained;
(f) and (2) carrying out vacuum impregnation on the porous silicon carbide ceramic for 0.5h, then curing the porous silicon carbide ceramic, wherein the curing temperature is set to 180 ℃, the curing time is set to 2h, finally cracking the cured silicon carbide ceramic/polycarbosilane in a protective atmosphere, the flow rate of the protective atmosphere is set to 100ml/min, the cracking temperature is set to 1200 ℃, and the cracking time is 2h, so that the densified silicon carbide ceramic is obtained.
Example 6
(a) Mechanically chopping lignocellulose to a certain length to obtain lignocellulose powder, wherein the length of the lignocellulose powder after mechanical chopping is 125 microns, and the length-diameter ratio is 25;
(b) carrying out vacuum stirring defoaming on the lignocellulose powder to obtain lignocellulose pulp, wherein the vacuum stirring defoaming rotating speed is set to 2000r/min, the time is set to 5min, and the vacuum degree is 10 Pa;
(c) slicing the wood fiber into pieces according to the designed digital three-dimensional model, and forming a lignocellulose/resin blank by utilizing a three-dimensional photocuring process;
(d) placing the lignocellulose/resin green body in an alumina crucible with silicon carbide coarse powder laid at the bottom, setting the heating rate to be 0.5 ℃/min, the pyrolysis temperature to be 1000 ℃, and the pyrolysis time to be 2h, and obtaining a lignocellulose carbon preform after pyrolysis;
(e) placing the lignocellulose carbon preform in a graphite crucible, embedding the lignocellulose carbon preform by coarse silicon particles, wherein the particle size of the coarse silicon particles is 5mm, the mass of the coarse silicon particles is 3 times of that of a lignocellulose carbon blank, the reaction temperature rise rate is 5 ℃/min, the reaction temperature of molten silicon is 1800 ℃, nitrogen is introduced for protection before the temperature reaches 1800 ℃, vacuumizing is performed when the temperature reaches 1800 ℃, the reaction time of the molten silicon is 0.5h under the vacuum condition, the temperature is raised to 2000 ℃ after the reaction is finished, residual silicon is removed, when the temperature is reduced to below 1000 ℃, nitrogen is removed, air is introduced, residual carbon is removed, and porous silicon carbide ceramic is obtained;
(f) and (2) carrying out vacuum impregnation on the porous silicon carbide ceramic for 0.5h, then curing the porous silicon carbide ceramic, wherein the curing temperature is set to 180 ℃, the curing time is set to 2h, finally cracking the cured silicon carbide ceramic/polycarbosilane in a protective atmosphere, the flow rate of the protective atmosphere is set to 100ml/min, the cracking temperature is set to 1400 ℃, and the cracking time is 2h, thus obtaining the densified silicon carbide ceramic.
Example 7
(a) Mechanically chopping lignocellulose to a certain length to obtain lignocellulose powder, wherein the length of the lignocellulose powder after mechanical chopping is 70 microns, and the length-diameter ratio is 25;
(b) adding the lignocellulose powder into a phenolic resin/absolute ethyl alcohol solution, carrying out vacuum centrifugal defoaming for 30min, wherein the volume ratio of the phenolic resin to the absolute ethyl alcohol solution is 2: 1, and setting the technological parameters of closed cycle spray granulation as follows: the inlet temperature of hot air is 85 ℃, the outlet temperature is 80 ℃, the rotating speed of an atomizer is 8000r/min, and the nitrogen flow rate is 100ml/min, so that the lignocellulose granulated powder with the particle size of 20 microns is obtained.
(c) Slicing according to the designed digital three-dimensional model, and forming a lignocellulose/resin green body by using a selective laser sintering process;
(d) placing the lignocellulose/resin green body in an alumina crucible with silicon carbide coarse powder laid at the bottom, setting the heating rate to be 0.5 ℃/min, the pyrolysis temperature to be 1000 ℃, and the pyrolysis time to be 3h, and obtaining a lignocellulose carbon preform after pyrolysis;
(e) placing the lignocellulose carbon preform in a graphite crucible, embedding the lignocellulose carbon preform by coarse silicon particles, wherein the particle size of the coarse silicon particles is 3mm, the mass of the coarse silicon particles is 3 times of that of a lignocellulose carbon blank, the reaction temperature rise rate is 5 ℃/min, the reaction temperature of molten silicon is 1450 ℃, nitrogen is introduced for protection before the temperature reaches 1650 ℃, vacuumizing is carried out when the temperature reaches 1650 ℃, the reaction time of the molten silicon is 1.5h under the vacuum condition, the temperature is raised to 2000 ℃ after the reaction is finished, residual silicon is removed, when the temperature is reduced to below 1000 ℃, nitrogen is removed, air is introduced, residual carbon is removed, and the porous silicon carbide ceramic is obtained;
(d) and (2) carrying out vacuum impregnation on the porous silicon carbide ceramic for 0.5h, then curing the porous silicon carbide ceramic, wherein the curing temperature is set to 180 ℃, the curing time is set to 2h, finally cracking the cured silicon carbide ceramic/polycarbosilane in a protective atmosphere, the flow rate of the protective atmosphere is set to 100ml/min, the cracking temperature is set to 1200 ℃, and the cracking time is 5h, so that the densified silicon carbide ceramic is obtained.
Example 8
(a) Mechanically chopping lignocellulose to a certain length to obtain lignocellulose powder, wherein the length of the lignocellulose powder after mechanical chopping is 125 microns, and the length-diameter ratio is 25;
(b) adding the lignocellulose powder into a phenolic resin/absolute ethyl alcohol solution, carrying out vacuum centrifugal defoaming for 30min, wherein the volume ratio of the phenolic resin to the absolute ethyl alcohol solution is 2: 1, and setting the technological parameters of closed cycle spray granulation as follows: the inlet temperature of hot air is 100 ℃, the outlet temperature is 85 ℃, the rotating speed of an atomizer is 12000r/min, and the nitrogen flow rate is 100ml/min, so that the lignocellulose granulated powder with the particle size of 70 microns is obtained.
(c) Slicing according to the designed digital three-dimensional model, and forming a lignocellulose/resin green body by using a selective laser sintering process;
(d) placing the lignocellulose/resin green body in an alumina crucible with silicon carbide coarse powder laid at the bottom, setting the heating rate to be 0.5 ℃/min, the pyrolysis temperature to be 1000 ℃, and the pyrolysis time to be 3h, and obtaining a lignocellulose carbon preform after pyrolysis;
(e) placing the lignocellulose carbon preform in a graphite crucible, embedding the lignocellulose carbon preform by coarse silicon particles, wherein the particle size of the coarse silicon particles is 3mm, the mass of the coarse silicon particles is 3 times of that of a lignocellulose carbon blank, the reaction temperature rise rate is 5 ℃/min, the reaction temperature of molten silicon is 1800 ℃, nitrogen is introduced for protection before the temperature reaches 1800 ℃, vacuumizing is carried out when the temperature reaches 1800 ℃, the reaction time of the molten silicon is 0.5h under the vacuum condition, the temperature is raised to 2000 ℃ after the reaction is finished, nitrogen is introduced to remove residual silicon, and when the temperature is reduced to below 1000 ℃, the nitrogen is removed, air is introduced to remove the residual carbon, so that the porous silicon carbide ceramic is obtained;
(f) and (2) carrying out vacuum impregnation on the porous silicon carbide ceramic for 0.5h, then curing the porous silicon carbide ceramic, wherein the curing temperature is set to 180 ℃, the curing time is set to 2h, finally cracking the cured silicon carbide ceramic/polycarbosilane in a protective atmosphere, the flow rate of the protective atmosphere is set to 100ml/min, the cracking temperature is set to 1400 ℃, and the cracking time is 2h, thus obtaining the densified silicon carbide ceramic.
Example 9
(a) Mechanically chopping lignocellulose to a certain length to obtain lignocellulose powder, wherein the length of the lignocellulose powder after mechanical chopping is 70 microns, and the length-diameter ratio is 7;
(b) adding the lignocellulose powder into a phenolic resin/absolute ethyl alcohol solution, carrying out vacuum centrifugal defoaming for 30min, wherein the volume ratio of the phenolic resin to the absolute ethyl alcohol solution is 2: 1, and setting the technological parameters of closed cycle spray granulation as follows: the inlet temperature of hot air is 125 ℃, the outlet temperature is 85 ℃, the rotating speed of an atomizer is 12000r/min, and the nitrogen flow rate is 100ml/min, so that the lignocellulose granulated powder with the particle size of 20 microns is obtained.
(c) Slicing the wood fiber/resin blank according to the designed digital three-dimensional model and then forming the wood fiber/resin blank by utilizing a three-dimensional spray printing process;
(d) placing the lignocellulose/resin green body in an alumina crucible with silicon carbide coarse powder laid at the bottom, setting the heating rate to be 0.5 ℃/min, the pyrolysis temperature to be 1000 ℃, and the pyrolysis time to be 3h, and obtaining a lignocellulose carbon preform after pyrolysis;
(e) placing the lignocellulose carbon preform in a graphite crucible, embedding the lignocellulose carbon preform by coarse silicon particles, wherein the particle size of the coarse silicon particles is 3mm, the mass of the coarse silicon particles is 3 times of that of a lignocellulose carbon blank, the reaction temperature rise rate is 5 ℃/min, the reaction temperature of molten silicon is 1800 ℃, nitrogen is introduced for protection before the temperature reaches 1800 ℃, vacuumizing is performed when the temperature reaches 1800 ℃, the reaction time of the molten silicon is 0.5h under the vacuum condition, the temperature is raised to 2000 ℃ after the reaction is finished, residual silicon is removed, when the temperature is reduced to below 1000 ℃, nitrogen is removed, air is introduced, residual carbon is removed, and porous silicon carbide ceramic is obtained;
(f) and (2) carrying out vacuum impregnation on the porous silicon carbide ceramic for 0.5h, then curing the porous silicon carbide ceramic, wherein the curing temperature is set to 180 ℃, the curing time is set to 2h, finally cracking the cured silicon carbide ceramic/polycarbosilane in a protective atmosphere, the flow rate of the protective atmosphere is set to 100ml/min, the cracking temperature is set to 1200 ℃, and the cracking time is 5h, so that the densified silicon carbide ceramic is obtained.
Example 10
(a) Mechanically chopping lignocellulose to a certain length to obtain lignocellulose powder, wherein the length of the lignocellulose powder after mechanical chopping is 125 microns, and the length-diameter ratio is 7;
(b) adding the lignocellulose powder into a phenolic resin/absolute ethyl alcohol solution, carrying out vacuum centrifugal defoaming for 30min, wherein the volume ratio of the phenolic resin to the absolute ethyl alcohol solution is 2: 1, and setting the technological parameters of closed cycle spray granulation as follows: the inlet temperature of hot air is 125 ℃, the outlet temperature is 85 ℃, the rotating speed of an atomizer is 12000r/min, and the nitrogen flow rate is 100ml/min, so that the lignocellulose granulated powder with the particle size of 20 microns is obtained.
(c) Slicing the wood fiber/resin blank according to the designed digital three-dimensional model and then forming the wood fiber/resin blank by utilizing a three-dimensional spray printing process;
(d) placing the lignocellulose/resin green body in an alumina crucible with silicon carbide coarse powder laid at the bottom, setting the heating rate to be 0.5 ℃/min, the pyrolysis temperature to be 1000 ℃, and the pyrolysis time to be 3h, and obtaining a lignocellulose carbon preform after pyrolysis;
(e) placing the lignocellulose carbon preform in a graphite crucible, embedding the lignocellulose carbon preform by using coarse silicon particles, wherein the particle size of the coarse silicon particles is 3mm, the mass of the coarse silicon particles is 3 times of that of a lignocellulose carbon blank, the reaction temperature rise rate is 5 ℃/min, the reaction temperature of molten silicon is 1450 ℃, nitrogen is introduced for protection before the temperature reaches 1450 ℃, vacuumizing is performed when the temperature reaches 1450 ℃, the reaction time of the molten silicon is 1.5h under the vacuum condition, the temperature is raised to be higher than the boiling point of silicon after the reaction of the molten silicon, nitrogen is introduced to remove residual silicon, and when the temperature is reduced to be lower than 1000 ℃, the nitrogen is removed, air is introduced to remove the residual carbon, so that the porous silicon carbide ceramic is obtained;
(f) and (2) carrying out vacuum impregnation on the porous silicon carbide ceramic for 0.5h, then curing the porous silicon carbide ceramic, wherein the curing temperature is set to 180 ℃, the curing time is set to 2h, finally cracking the cured silicon carbide ceramic/polycarbosilane in a protective atmosphere, the flow rate of the protective atmosphere is set to 100ml/min, the cracking temperature is set to 1400 ℃, and the cracking time is 3h, thus obtaining the densified silicon carbide ceramic.
The silicon carbide ceramic obtained by the embodiment has no residual silicon and carbon, has excellent high-temperature mechanical property and high chemical stability, and can meet the use requirements of extreme environments.
In conclusion, the preparation of lignocellulose derived silicon carbide ceramic with a complex structure can be realized, so that green 3D printing of the biomass material is realized, the problem that the silicon carbide ceramic is difficult to machine and process is solved, and the silicon carbide ceramic product has no residual silicon and carbon and has remarkable advantages under a high-temperature condition.
It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.