Low-temperature crystallized SiBCN ceramic and preparation method thereof

Abstract

The invention relates to the technical field of ceramic material processing, in particular to low-temperature crystallized SiBCN ceramic and a preparation method thereof. The SiBCN ceramic materials with different components, different crystallinity degrees and microstructures are prepared by adding an auxiliary agent, namely nano Ti or nano TiO2, into PBSZ powder and adopting a ball-milling blending method and changing the doped auxiliary agent, the mass ratio of the doped auxiliary agent and the heat treatment temperature of the doped auxiliary agent. According to the material, low-temperature crystallization is maintained, and meanwhile, the problem that the dielectric property of pure SiBCN ceramic is poor is greatly solved. The method has the advantages that the process is simple, the reaction is controllable, the SiBCN ceramic with a large number of crystals is obtained after heat treatment at low temperature (less than or equal to 1400 DEG C), and the SiBCN ceramic has good electromagnetic wave loss performance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ceramic material processing, in particular to a low-temperature crystallized SiBCN ceramic and a preparation method thereof. BACKGROUND

[0002] SiBCN composite ceramics have important application prospects in aerospace high-temperature structural components, high-temperature wave-absorbing materials, and new-generation high-temperature dielectric energy storage devices, due to their excellent high-temperature stability, oxidation resistance, and adjustable electromagnetic properties. From the application scenarios of ceramics, it can be seen that excellent high-temperature comprehensive performance is pursued by most researchers. However, the SiBCN ceramics prepared by the existing technology can only generate crystals at a temperature above 1600 ℃, which greatly limits the application field of SiBCN ceramics.

[0003] SiBCN ceramics have excellent microwave attenuation performance, mainly due to the conductive loss and polarization loss generated by the crystals therein. However, it is difficult to obtain SiBCN ceramics with crystals below 1600 ℃. Researchers usually use methods such as precursor modification, hot-pressing sintering, and adding low-temperature sintering additives to optimize the performance, but often low temperature and performance cannot be achieved simultaneously. Precursor modification is a generally applicable method. (CN117024144A) obtained a hyperbranched polyborosilazane precursor containing benzene rings by one-pot method. After pyrolysis, the electromagnetic absorption performance of the sample was improved, but the ceramic was still in an amorphous state below 1400 ℃. (CN115959911B) mentioned in the literature that by preparing a hyperbranched polyborosilazane with less carbon crosslinked by divinylbenzene, a ceramic with high-temperature stability and good wave-absorbing performance was obtained. Studies have shown that the ceramic can still maintain an amorphous structure below an annealing temperature of 1400 ℃. (CN112851359B) mentioned that the SiBCN precursor was dissolved into a spinning solution, and SiBCN nanofibers were obtained by pyrolysis. When the pyrolysis temperature was increased to 1600 ℃, SiC phase was precipitated from the SiBCN ceramic, the fiber surface was smooth and the morphology was complete, so that the SiBCN nanofiber obtained excellent electromagnetic wave absorption performance. However, the SiBCN nanofiber mainly consisted of free carbon phase and SiBCN amorphous matrix phase at a pyrolysis temperature of 1600 ℃, so the SiBCN nanofiber basically had no wave-absorbing ability at 1600 ℃. Sintering additives such as MAS glass phase and rare earth oxides can help to reduce the crystallization temperature and sintering temperature through mechanisms such as viscous flow and grain boundary diffusion, but they will form impurity phases and reduce the comprehensive performance of the material.

[0004] Currently, SiBCN ceramic research mainly focuses on the improvement of high-temperature performance and application, and there are few studies on reducing the crystallization temperature and optimizing the performance of the ceramic. Therefore, it is necessary to develop a simple and efficient SiBCN ceramic preparation method to reduce the crystallization temperature of the ceramic, reduce the production cost, and increase the application field of SiBCN ceramics. SUMMARY

[0005] To achieve one of the above purposes, the present application provides a low-temperature crystallized SiBCN ceramic and a preparation method thereof, which is simple in process and controllable in reaction, and can obtain a SiBCN ceramic with a large number of crystal structures after heat treatment at a low temperature (≤1400 ℃), thereby overcoming the problems of amorphous state and poor dielectric performance of SiBCN ceramic at a low temperature. The technical scheme of the present application is as follows: In a first aspect, the present application provides a preparation method of a low-temperature crystallized SiBCN ceramic, comprising the following steps: S1, heating and curing a polyborosilazane (PBSZ) resin, heat preservation molding, and ball milling to obtain a polyborosilazane (PBSZ) ball-milled powder; S2, adding an additive to the above polyborosilazane (PBSZ) ball-milled powder and mixing and ball milling to obtain a mixed powder; S3, pressing the mixed powder into a sheet to obtain a ceramic sample; S4, heat treating the ceramic sample to obtain a SiBCN ceramic; The additive in step S2 comprises nano-Ti or nano-TiO2.

[0006] Preferably, the powder mass of the additive in step S2 is 0.1-20 wt.% of the mass of the PBSZ ball-milled powder, and most preferably 10 wt.%. When the content is too high, the performance will be unbalanced.

[0007] Preferably, the heat treatment temperature in step S4 is 800-1400 ℃, and the heat treatment time is 1-6 h. The present application aims to low-temperature crystallization, so 1400 ℃ is taken as the critical temperature. A temperature that is too high may cause abnormal crystallization, poor impedance matching, and reduced electromagnetic attenuation.

[0008] Preferably, the particle size of the nano-Ti and nano-TiO2 is 5-100 nm. A particle size that is too small or too large is not conducive to the formation of crystals and may cause agglomeration.

[0009] Preferably, in step S1, the curing temperature is 180-350 ℃, and the heat preservation time is 1-6 h.

[0010] Further preferably, in steps S1 and S2, the specific steps of ball milling are the same, which include: placing the powder into a vacuum ball mill tank, ball milling at a revolution speed of 100-300 rpm / min in a planetary ball mill under a protective atmosphere for 1-5 h, wherein the mass ratio of grinding balls to powder is (5-20):1, the protective atmosphere comprises argon and nitrogen, and the grinding balls comprise stainless steel balls.

[0011] Further preferably, the step S1 specifically comprises curing and forming the polyborosilazane resin in a tube furnace under a protective atmosphere, the protective atmosphere comprising argon and nitrogen.

[0012] Further preferably, the step S4 specifically comprises heat treating the ceramic sample in a tube furnace under a protective atmosphere, the protective atmosphere comprising argon and nitrogen.

[0013] Preferably, in the steps S1 and S4, the heating rate is 1-10 ℃ / min.

[0014] In a second aspect, the present application provides a low-temperature crystallized SiBCN ceramic prepared by the method of the first aspect.

[0015] Compared with the prior art, the present application has the following advantages: (1) The low-temperature crystallized SiBCN ceramic prepared by the present application can be crystallized at 800 ℃, overcoming the technical bottleneck that SiBCN ceramic is difficult to be crystallized at low temperature and is in an amorphous state after low-temperature heat treatment and has poor dielectric performance at low temperature.

[0016] (2) The present application uses nano-Ti / TiO2 as a doping aid, and after ball milling mechanical mixing, different SiBCN ceramics with different crystallinities are obtained by changing the doping content of nano-Ti / TiO2 and the heat treatment temperature of the ceramic. With the increase of the doping amount of nano-Ti / TiO2, the number of crystals in the SiBCN ceramic increases and the crystallization degree increases, and the electromagnetic wave loss capacity of the ceramic is improved; with the increase of the heat treatment temperature, the crystallization degree of the ceramic increases, the type of crystal increases, and the dielectric performance of the ceramic increases.

[0017] (3) The present application uses the ball milling blending method, and the preparation process is simple and the reaction is controllable. After low-temperature (≤1400 ℃) heat treatment, SiBCN ceramic with a large number of crystals is obtained, and the crystallization performance and dielectric performance are good. By changing the doping aid, the mass ratio thereof, and the heat treatment temperature, SiBCN ceramic materials with different compositions, different crystallization degrees, and microstructures can be prepared, which provides the possibility for preparing SiBCN materials with low-temperature crystallization and excellent dielectric performance. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and those skilled in the art can obtain other drawings according to these drawings without any creative effort.

[0019] Figure 1XRD patterns of SiBCN ceramics prepared for Example 1, Example 2 and Comparative Example 1 of the present application; (a) XRD patterns of samples PTi10-800, PTi10-1000, PTi10-1400 at different temperatures; (b) XRD patterns of samples PTi0-1000, PTi0.1-1000, PTi10-1000, PTi15-1000 with different doping amounts of nano-Ti; Figure 2 Reflection loss comparison chart of SiBCN ceramics prepared for Example 1~3 and Comparative Example 1 of the present application; (a) Reflection loss values of samples PTi0-1000, PTi0.1-1000, PTi10-1000, PTi15-1000, PTiO220-1000 at the same temperature; (b) Reflection loss values of samples PTi10-800, PTi10-1000, PTi10-1400 with the same doping amount; Figure 3 TEM patterns of SiBCN ceramics prepared for Example 2 and Comparative Example 1 of the present application; (a) and (b) are TEM patterns of sample PTi0-1000; (c) and (d) are TEM patterns of sample PTi15-1000. DETAILED DESCRIPTION

[0020] The embodiments of the present application are described in detail below with reference to the accompanying drawings. The embodiments described below are examples for explaining the present application and should not be understood as limiting the present application.

[0021] It should be noted that the terms "first", "second" are used only for the purpose of description and should not be understood as indicating or implying relative importance or implying the number of the technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. Further, in the description of the present application, unless otherwise specified, the meaning of "a plurality of" is two or more.

[0022] In this document, the terms "containing", "including" or "comprising" are open expressions, i.e. including the indicated content of the present application, but not excluding other aspects.

[0023] In this document, the term "optional", "optionally" or "optional" generally means that the event or condition described subsequently can but does not necessarily occur, and the description includes the case where the event or condition occurs, as well as the case where the event or condition does not occur.

[0024] It should be noted that the application adopts a ball milling blending method, has simple preparation process, controllable reaction, and obtains SiBCN ceramic with a large number of crystals after low-temperature (≤1400 ℃) heat treatment, and overcomes the problems that SiBCN ceramic is in an amorphous state at low temperature and has poor dielectric performance.

[0025] Firstly, the mechanical friction collision of ball milling has a certain activation effect, and ball milling can not only uniformly mix the SiBCN precursor, but also enhance the pre-reaction between the interfaces, which is helpful to the subsequent catalysis; the free carbon generated in the thermal decomposition of the SiBCN precursor during the heating process reacts with Ti to form TiC crystals under the catalysis of nano Ti / TiO2. The conductive loss and polarization loss generated by the crystals improve the loss ability of SiBCN ceramic to electromagnetic waves, and the low-temperature heat treatment avoids excessive crystallization of the ceramic, realizes effective absorption of electromagnetic waves, prevents the sharp increase of electrical conductivity, and destroys the impedance matching characteristics, solves the problems of low-temperature crystallization and high-temperature performance imbalance.

[0026] The technical solutions in the embodiments of the application will be described clearly and completely in combination with the drawings in the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments. Based on the embodiments of the application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the application.

[0027] It should be noted that in the embodiments of the application, the polyborosilazane (PBSZ) resin is prepared by referring to the method of the literature “Rational design of SiBCN ceramics with excellent attenuation to strong electromagnetic-wave-absorbing properties at low frequency”.

[0028] Embodiment 1 The embodiment provides a preparation method of SiBCN ceramic crystallized at low temperature, and is specifically used for screening and optimizing the heat treatment temperature of SiBCN ceramic, and comprises the following steps: ① Put the polyborosilazane (PBSZ) resin into a tube furnace, and heat to 350 ℃ at a rate of 5 ℃ / min under the protection of argon atmosphere, and keep the temperature for 6 h to make the PBSZ resin solidify and form; ② Ball milling I: put the solidified precursor and stainless steel balls into a vacuum ball mill jar, the mass ratio of the balls to the material is 10:1, ball mill the mixture in a planetary ball mill at a speed of 300 rpm / min under the protection of argon atmosphere for 5 h to obtain PBSZ ball milling powder; ③Ball milling two: add nano-Ti powder to the ball milling tank, the mass of the powder is 10wt.% of the mass of PBSZ powder, under the condition of a ball-to-material mass ratio of 10:1, ball mill for 3 h at a speed of 200 rpm / min in an argon atmosphere; ④Take out the blended and ball-milled powder, press it into a sheet to obtain a ceramic sample; This embodiment respectively sets different heat treatment temperatures for the above ceramic samples for crystallization testing, and sets 3 samples, which are heat treated at 800 ℃, 1000 ℃ and 1400 ℃ respectively; ⑤Put the pressed sample into a vertical tube furnace for heat treatment, the heating rate is in the range of 5 ℃ / min, under the protection of argon atmosphere, heat treatment at 800 ℃, 1000 ℃ and 1400 ℃ respectively for 6 h, and then cool down in the furnace to obtain low-temperature crystallized SiBCN ceramics, which are respectively recorded as sample 1 (PTi10-800), sample 2 (PTi10-1000) and sample 3 (PTi10-1400).

[0029] The nano-Ti (purchased from Shandong Keyuan Biotech Co., Ltd.) added in step ③ has a particle size of 60 nm.

[0030] The low-temperature crystallized SiBCN ceramics prepared in this embodiment are tested by Figure 1 It can be observed from the XRD spectrum of (a) that when the heat treatment temperature is 1400 ℃, sample 3 (PTi10-1400) has obvious diffraction peaks, and analysis shows that TiC crystals are generated; when the heat treatment temperature is 1000 ℃, sample 2 (PTi10-1000) has relatively obvious diffraction peaks; and when the heat treatment temperature is 800 ℃, sample 1 (PTi10-800) also grows crystals, with weak diffraction peaks.

[0031] Example 2 This embodiment provides a preparation method of low-temperature crystallized SiBCN ceramics, which is specifically used to screen and optimize the amount of nano-Ti powder added, and includes the following steps: ①Put the polyborosilazane (PBSZ) resin into a tube furnace, and heat it to 350 ℃ at a rate of 5 ℃ / min under the protection of argon atmosphere and keep it for 6 h to solidify and form; ②Ball milling one: put the solidified precursor and stainless steel balls into a vacuum ball milling tank, the ball-to-material mass ratio is 10:1, ball mill for 5 h at a speed of 300 rpm / min in an argon atmosphere in a planetary ball mill to obtain PBSZ ball-milled powder; This embodiment respectively sets different doping amounts of nano-Ti in the above PBSZ ball-milled powder for feasibility test, sets 4 samples, and the doping amounts are 0.1 wt.%, 5 wt.%, 10 wt.% (same as sample 2 in embodiment 1), and 15 wt.% respectively; ③ Ball-milling two: nano-Ti powder is further added to the ball mill tank, and the powder mass is 0.1 wt.%, 5 wt.%, and 10 wt.% of the mass of PBSZ powder respectively, under the condition of a ball-to-material mass ratio of 10:1, and under an argon atmosphere, the speed is 200 rpm / min, and the ball milling time is 3 h; ④ The blended and ball-milled powder is taken out and pressed into a sheet; ⑤ The pressed sample is placed in a vertical tube furnace for heat treatment, the heating rate is 5 ℃ / min, the heat treatment temperature is 1000 ℃ under a protective atmosphere of argon, and the heat preservation time is 6 h, and after the furnace is cooled, low-temperature crystallized SiBCN ceramic is obtained, and is respectively recorded as sample 4 (PTi0.1-1000), sample 5 (PTi5-1000), sample 2 (PTi10-1000), and sample 6 (PTi15-1000).

[0032] The nano-Ti (purchased from Shandong Keyuan Biotech Co., Ltd.) doped in step ③ has a particle size of 60 nm.

[0033] Comparative example 1 This comparative example provides a preparation method of pure SiBCN ceramic, which is different from embodiment 2 in that no nano-Ti is added, that is, step ③ is removed, and the remaining steps are the same, and the obtained SiBCN ceramic is recorded as PTi0-1000.

[0034] The XRD of the SiBCN ceramics with different nano-Ti doping amounts in embodiment 2 and the pure SiBCN ceramic without Ti doping in comparative example 1 is shown in FIG. 2 (b). Figure 1 As can be seen from FIG. 2 (b), when no nano-Ti is doped, the obtained SiBCN ceramic has no crystal, and the whole is in an amorphous state; the sample 4 (PTi0.1-1000) doped with 0.1 wt.% of nano-Ti has a weak crystal diffraction peak, which indicates that nano-Ti can promote the generation of crystal phase of SiBCN ceramic.

[0035] Further, the SiBCN ceramics of sample 6 in embodiment 2 and sample 1 in comparative example 1 are tested by electron microscopy, as shown in FIG. 3. Figure 3 As can be seen from FIG. 3 (a) and (b), the pure SiBCN is amorphous after heat treatment at 1000 ℃, and no crystal appears under transmission test. As can be seen from FIG. 3 (c) and (d), the sample 6 (PTi15-1000) doped with 15 wt.% of nano-Ti has a large number of crystals, and the crystal size is larger than that of sample 2 (PTi10-1000) doped with 10 wt.% of nano-Ti. Figure 3 Figure 3 ​As can be seen in (c) and (d) of FIG. 6, after the same heat treatment, the SiBCN ceramic doped with 15% nano-Ti generates a large number of nanoscale spherical TiC crystals. According to the XRD test result, it is known that it is the TiC (111) crystal face through the measurement of the crystal spacing.

[0036] Example 3 The present example provides a method for preparing a low-temperature crystallized SiBCN ceramic, and a nano-TiO2 is selected as an additive, which comprises the following steps: ① Put the polyborosilazane (PBSZ) resin into a tube furnace, and heat it to 350 ℃ at a rate of 10 ℃ / min under the protection of argon gas and keep it for 3 h to make it solidify and form; ② Ball milling I: put the solidified precursor and stainless steel balls into a vacuum ball mill jar, and ball mill them in a planetary ball mill at a speed of 300 rpm / min under the protection of argon gas for 5 h to obtain PBSZ ball-milled powder; ③ Ball milling II: add nano-TiO2 powder to the ball mill jar, and ball mill them at a speed of 300 rpm / min under the protection of argon gas for 5 h, with the mass ratio of the powder to the PBSZ powder being 20wt.%; ④ Take out the blended and ball-milled powder and press it into a sheet; ⑤ Put the pressed sample into a vertical tube furnace for heat treatment, and heat it at a rate of 10 ℃ / min under the protection of argon gas, and keep it at a temperature of 1000 ℃ for 6 h, and then cool it down in the furnace to obtain a low-temperature crystallized SiBCN ceramic, which is denoted as sample PTiO220-1000.

[0037] The nano-TiO2 (purchased from Shanghai Maikelin Biochemical Technology Co., Ltd.) added in step ③ has a particle size of 100 nm.

[0038] The low-temperature crystallized SiBCN ceramic prepared in the present example 3 has crystals generated.

[0039] To verify the dielectric properties of the above examples and comparative examples, the electromagnetic parameters of the samples were characterized at room temperature by using a coaxial transmission line method (vector network analyzer, Keysight E5071C, Malaysia), and the ceramic powder and paraffin were mixed in a mass ratio of 3:7 and pressed into a coaxial ring with an outer diameter of 7.00 mm, an inner diameter of 3.00 mm, and a thickness of 2.5-3.5 mm. The reflection loss of the material was calculated by the formula. The reflection loss value is a negative decibel value, and its absolute value directly measures the strength of the reflection. In this study, the smaller the reflection loss value, the stronger the loss ability of the ceramic to the electromagnetic wave, and the better the impedance matching.

[0040] The scattering loss values of the SiBCN ceramic samples of Examples 1, 2 and Comparative Example 1 were tested as shown in Table 1 and FIG. 2. Figure 2 It can be seen that the overall reflection loss value of the PTi10-800 sample is not large, and the minimum reflection loss value is -3.69 dB, indicating that the sample has a small electromagnetic wave loss capacity, but is higher than that of pure SiBCN ceramic; the reflection loss value of the PTi10-1000 sample is close to -30 dB, indicating that the ceramic has a certain electromagnetic wave loss capacity; the reflection loss value of the PTi10-1400 sample is -26.57 dB, which is lower than that of the PTi10-1000 sample, indicating that as the temperature increases, the crystallinity becomes better, but the increase in the number of crystals may increase the conductivity and thus reduce the overall loss.

[0041] The SiBCN ceramic obtained in Comparative Example 1 has no crystal and is in an amorphous state, and the reflection loss is very small, only -1.77 dB, which indicates that pure SiBCN has almost no ability to lose electromagnetic waves; similarly, the reflection loss value of the PTi0.1-1000 sample is not large, but the absolute value is still higher than that of pure SiBCN ceramic; but when the Ti content is increased to 15 wt.%, the reflection loss is -14.71 dB, which is lower than that of the sample PTi10-1000; therefore, the most preferred Ti content in the present application is 10 wt.% and the most preferred temperature is 1000°C.

[0042] When the auxiliary agent in Example 3 is replaced with TiO2 and the content is increased to 20 wt.%, the reflection loss value of the sample PTiO220-1000 reaches -36.10 dB, which indicates that the addition of TiO2 makes the crystallinity of the ceramic better and the dielectric loss capacity increases.

[0043] Table 1 Reflection loss values of SiBCN ceramic samples of Examples 1, 2 and Comparative Example 1

[0044] Example 4 The present embodiment provides a method for preparing a low-temperature crystallized SiBCN ceramic, comprising the following steps: ① Put the polyborosilazane (PBSZ) resin into a tube furnace, and increase the temperature to 180°C at a rate of 1°C / min under a protective atmosphere of argon and keep it for 6 h to solidify and form; ② Ball milling 1: Put the solidified precursor and stainless steel balls into a vacuum ball mill jar, and ball mill at a speed of 100 rpm / min in a planetary ball mill under an argon atmosphere for 1 h to obtain PBSZ ball milled powder; ③ Ball milling two: add nano-Ti powder to the ball milling tank, the powder mass is 0.1wt.% of the mass of PBSZ powder, under the condition of ball-to-material mass ratio of 20:1, ball mill for 1 h at a speed of 100 rpm / min in an argon atmosphere; ④ Take out the blended and ball-milled powder and press it into a sheet; ⑤ Put the pressed sample into a vertical tube furnace for heat treatment, the heating rate is in the range of 1 ℃ / min, the heat treatment temperature is 1400 ℃ under the protection of argon atmosphere, and the heat preservation time is 1 h, and the low-temperature crystallized SiBCN ceramic is obtained after furnace cooling.

[0045] The nano-Ti particle size incorporated in step ③ is 5 nm.

[0046] The low-temperature crystallized SiBCN ceramic prepared in this embodiment 4 has crystal generation, and the reflection loss value is -5.97 dB, and the ceramic has a certain electromagnetic wave loss capacity.

[0047] Example 5 The embodiment provides a preparation method of a low-temperature crystallized SiBCN ceramic, including the following steps: ① Put polysilazane (PBSZ) resin into a tube furnace, and heat to 350 ℃ at a rate of 1 ℃ / min under the protection of argon atmosphere, and heat preservation for 1 h to make it solidify and form; ② Ball milling one: put the solidified precursor and stainless steel balls into a vacuum ball milling tank, the ball-to-material mass ratio is 20:1, ball mill for 5 h at a speed of 100 rpm / min in a planetary ball mill under an argon atmosphere, and PBSZ ball-milled powder is obtained; ③ Ball milling two: add nano-Ti powder to the ball milling tank, the powder mass is 5wt.% of the mass of PBSZ powder, under the condition of ball-to-material mass ratio of 20:1, ball mill for 5 h at a speed of 100 rpm / min in an argon atmosphere; Take out the blended and ball-milled powder and press it into a sheet; ⑤ Put the pressed sample into a vertical tube furnace for heat treatment, the heating rate is in the range of 5 ℃ / min, the heat treatment temperature is 1400 ℃ under the protection of argon atmosphere, and the heat preservation time is 1 h, and the low-temperature crystallized SiBCN ceramic is obtained after furnace cooling.

[0048] The nano-Ti particle size incorporated in step ③ is 5 nm.

[0049] The low-temperature crystallized SiBCN ceramic prepared in this embodiment 5 has crystal generation, and the reflection loss value is -10.95 dB, and the ceramic has a certain electromagnetic wave loss capacity.

[0050] Comparative Example 2 The comparative example 1 provides a preparation method of amorphous SiBCN ceramic, which is different from the example 2 in that the additive in step ③ is nano BN powder, the powder particle size is 500 nm, and the other steps are the same.

[0051] The SiBCN ceramic obtained by the comparative example 2 is amorphous, and has no attenuation ability to electromagnetic waves due to no generation of crystal dielectric phase.

[0052] The above described examples are part of the embodiments of the present application, rather than all the embodiments. The detailed description of the embodiments of the present application is not intended to limit the scope of the claimed application, but only represents selected embodiments of the present application. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments in the present application without creative labor belong to the scope of protection of the present application.

Claims

1. A method for producing a low-temperature crystallized SiBCN ceramic, characterized by, The method comprises the following steps: S1, heating and curing the polyborosilazane resin, keeping warm and forming, and ball milling to obtain polyborosilazane ball-milled powder; S2, adding an additive to the polyborosilazane ball-milled powder and mixing and ball milling to obtain a mixed powder; S3, pressing the mixed powder into a sheet to obtain a ceramic sample; S4, heat treating the ceramic sample to obtain SiBCN ceramic; The additive in step S2 comprises nano-Ti or nano-TiO2.

2. The method of claim 1, wherein the low-temperature crystallized SiBCN ceramic is characterized by, The mass of the additive in step S2 is 0.1-20 wt.% of the mass of the polyborosilazane ball-milled powder.

3. The method of claim 1, wherein the low-temperature crystallized SiBCN ceramic is characterized by, The heat treatment temperature in step S4 is 800-1400 ℃, and the heat treatment time is 1-6 h.

4. The method of claim 1, wherein the low-temperature crystallized SiBCN ceramic is characterized by, The particle size of the nano-Ti or nano-TiO2 is 5-100 nm.

5. The method of claim 1, wherein the low-temperature crystallized SiBCN ceramic is characterized by, In step S1, the curing temperature is 180-350 ℃, and the holding time is 1-6 h.

6. The method of claim 1, wherein the low-temperature crystallized SiBCN ceramic is characterized by, In steps S1 and S2, the specific steps of ball milling are the same, which comprise: placing the powder into a vacuum ball mill tank, ball milling at a revolution speed of 100-300 rpm / min in a planetary ball mill under a protective atmosphere for 1-5 h; wherein the mass ratio of grinding balls to powder is (5-20):1, and the protective atmosphere comprises argon and nitrogen.

7. The method of claim 1, wherein the low-temperature crystallized SiBCN ceramic is characterized by, In step S1, the polyborosilazane resin is cured and formed in a tube furnace under a protective atmosphere, and the protective atmosphere comprises argon and nitrogen.

8. The method of claim 1, wherein the low-temperature crystallized SiBCN ceramic is characterized by, In step S4, the ceramic sample is heat treated in a tube furnace under a protective atmosphere, and the protective atmosphere comprises argon and nitrogen.

9. The method of claim 1, wherein the low-temperature crystallized SiBCN ceramic is characterized by, In steps S1 and S4, the heating rate is 1-10 ℃ / min.

10. A low-temperature crystallized SiBCN ceramic prepared by the method of any one of claims 1-9.

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