A method for preparing a metal-based siCN dense ceramic body

Abstract

The application relates to a preparation method of a metal-based SiCN dense ceramic body and belongs to the technical field of precursor-derived ceramics. The application discloses a preparation method of a metal-based SiCN dense ceramic body, which comprises the following steps: carrying out a second reaction on a liquid metal-containing SiCN ceramic precursor to prepare a solid metal-containing vinylsilazane gel; grinding the solid metal-containing vinylsilazane gel to obtain a metal-containing vinylsilazane powder; mixing the metal-containing vinylsilazane powder with the liquid metal-containing SiCN ceramic precursor, and then performing die molding and cold isostatic pressing to obtain a metal-containing vinylsilazane block; carrying out a third reaction on the block to prepare a metal-based SiCN ceramic embryo; immersing the embryo in the liquid metal-containing SiCN ceramic precursor, and then sequentially performing a fourth reaction and a fifth reaction after taking out the embryo; and repeating the above steps 1-6 times to prepare the metal-based SiCN dense ceramic body. The preparation method can be suitable for preparing large-size and complex-shaped components, and can guarantee the compactness and stability of the metal-based SiCN dense ceramic body G.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of precursor-derived ceramics and relates to a preparation method of a metal-based SiCN dense ceramic body. BACKGROUND

[0002] In extreme environments such as high temperature and high pressure, silicon-based ceramics and their composite materials are widely used in the extreme working environment due to their excellent properties such as high strength and high thermal stability. The precursor-derived ceramic technology is concerned in the preparation of silicon-based ceramic materials because it can design the structure at the molecular scale of organic polymers, making the converted ceramic composition uniform. Silicon carbon nitride (SiCN) ceramic has good heat shock resistance, oxidation resistance and chemical corrosion resistance and is widely used in the fields of information, electronics, aerospace, etc. SiAlCN precursor ceramic has a wide application prospect in the field of ultra-high temperature sensors due to its excellent thermal mechanical properties and thermal stability.

[0003] At present, the metal-based SiCN ceramic precursor mainly uses polysilazane and organometallic compounds as raw materials and is synthesized by the reaction between N-H in polysilazane and organometallic compounds. For example, Yongdong et al. (Ceramics International, 2018, 44, 22473-22480) successfully prepared SiAlCN precursor by reacting liquid polysilazane (PSN-1) with aluminum isopropoxide (Aluminum isopropoxide, Al(OCH(CH3)2)3) and successfully applied it to temperature sensors; Lamuel David et al. (ACS Appl. Mater. Interfaces, 2014, 6, 16056-16064) prepared SiAlCN ceramic precursor for Li-ion electrode spray coating by physically mixing aluminum propoxide and poly(urea methyl vinyl) silazane (Ceraset) at room temperature for 24 h, drying at 80℃ in an inert atmosphere and then heat curing; Zhang Jieqiang et al. (Organic Silicon Materials, 2010, 24, 211-214) added Al powder to polysilazane (PSN-1) to generate SiAlCN ceramic precursor containing new phases such as AlN, which effectively improved the ceramic yield and reduced the porosity of the ceramic. The above polysilazane precursor is sensitive to air and water and is prone to introduce excess oxygen, which brings inconvenience to operation and storage.

[0004] And in the preparation of metal-based SiCN ceramic body, because it is a composite ceramic system, it is difficult to use traditional powder sintering methods such as traditional hot-pressing sintering or spark plasma sintering; although these methods can improve the density and mechanical properties of the ceramic, these methods are not suitable for preparing large-size and complex-shaped components; and the traditional pressureless sintering process generally needs to add sintering aids, which will introduce impurities into the ceramic. SUMMARY

[0005] The purpose of the present application is to solve the above-mentioned problems existing in the prior art, and to provide a preparation method of metal-based SiCN dense ceramic body without adding other additives and with simple preparation process, so that the prepared metal-based SiCN dense ceramic body has high density, low porosity and high stability.

[0006] The purpose of the present application can be achieved by the following technical solutions:

[0007] A preparation method of metal-based SiCN dense ceramic body, comprising:

[0008] S1, using liquid vinyl silazane monomer and metal-based compound as raw materials, carrying out first reaction to obtain liquid metal-containing vinyl silazane compound A;

[0009] S2, mixing the liquid metal-containing vinyl silazane compound A with a free radical initiator to obtain liquid metal-containing SiCN ceramic precursor B;

[0010] S3, carrying out second reaction on the liquid metal-containing SiCN ceramic precursor B to obtain solid metal-containing vinyl silazane gel C; grinding the solid metal-containing vinyl silazane gel C to obtain metal-containing vinyl silazane powder D;

[0011] S4, mixing the metal-containing vinyl silazane powder D with the liquid metal-containing SiCN ceramic precursor B, and then performing die molding and cold isostatic pressing to obtain metal-containing vinyl silazane bulk E;

[0012] S5, carrying out third reaction on the metal-containing vinyl silazane bulk E to obtain metal-based SiCN ceramic body F;

[0013] S6, immersing the metal-based SiCN ceramic body F in the liquid metal-containing SiCN ceramic precursor B, and then sequentially carrying out fourth reaction and fifth reaction;

[0014] S7, repeating the step S6 for 1-6 times to obtain metal-based SiCN dense ceramic body G.

[0015] The application takes liquid metal-containing vinylsilazane compound A as raw material, and introduces liquid metal-containing vinylsilazane compound A multiple times in subsequent preparation process to ensure the density and stability of metal-based SiCN dense ceramic body G; and the preparation method has simple raw materials and convenient operation, and can be suitable for preparing large-size and complex-shaped components.

[0016] The liquid metal-containing SiCN ceramic precursor B prepared by directly mixing liquid metal-containing vinylsilazane compound A with a free radical initiator is mixed with metal-containing vinylsilazane powder D obtained by solidification and grinding of the liquid metal-containing SiCN ceramic precursor B in a certain proportion. The liquid metal-containing SiCN ceramic precursor B has certain viscosity, which is beneficial to the die forming of the metal-containing vinylsilazane powder D without adding other additives, and is beneficial to increasing the density and micro-morphology of the ceramic block after sintering. If the metal-containing vinylsilazane powder D is directly die formed, cold isostatic pressing or the addition amount of the liquid metal-containing SiCN ceramic precursor B is too small, the density and strength of the metal-containing vinylsilazane block E will not change obviously compared with the metal-containing vinylsilazane powder D; if the addition amount of the liquid metal-containing SiCN ceramic precursor B is too large, it is difficult to die form, which affects the density and micro-morphology of the metal-containing vinylsilazane block E.

[0017] The metal-based SiCN ceramic embryo F is also immersed in the liquid metal-containing SiCN ceramic precursor B, which is the raw material for preparing the metal-based SiCN ceramic embryo F. Immersing the metal-based SiCN ceramic embryo F in the liquid metal-containing SiCN ceramic precursor B can make the liquid metal SiCN ceramic precursor B immerse in the pores of the metal-based SiCN ceramic embryo F, reduce the porosity of the metal-based SiCN ceramic embryo F and increase its density.

[0018] Preferably, the vinylsilazane monomer in step S1 is one or both of trimethyltrivinylcyclotrisilazane and tetramethyltetraethenylcyclotetrasiilazane.

[0019] Preferably, the metal element in the metal-based compound in step S1 is one or more of aluminum, yttrium, nickel, hafnium, lithium, iron, cobalt, lanthanum, zirconium, titanium, beryllium, magnesium, calcium, vanadium and the like.

[0020] Further preferably, the metal-based compound is one or more of acetylacetone metal salt, metal alkoxide and metallocene compound.

[0021] More preferably, the acetylacetone metal salt includes one or more of acetylacetone aluminum, acetylacetone iron, acetylacetone zirconium, acetylacetone titanium, acetylacetone cobalt, acetylacetone nickel, acetylacetone niobium, acetylacetone yttrium, acetylacetone beryllium, acetylacetone lanthanum, acetylacetone magnesium, acetylacetone calcium, acetylacetone vanadium.

[0022] The metal alkoxide includes one or more of aluminum alkoxide, iron alkoxide, zirconium alkoxide, titanium alkoxide, cobalt alkoxide, niobium alkoxide, nickel alkoxide, yttrium alkoxide, lanthanum alkoxide, beryllium alkoxide, magnesium alkoxide, calcium alkoxide;

[0023] The metallocene compound includes one or more of metallocene iron compound, metallocene zirconium compound, metallocene titanium compound, metallocene cobalt compound, metallocene nickel compound, metallocene niobium compound, metallocene yttrium compound, metallocene beryllium compound, metallocene lanthanum compound, metallocene magnesium compound.

[0024] As preferred, the mass ratio of the vinyl silazane monomer and the metal-based compound in step S1 is 100:(0.1-50).

[0025] As preferred, the temperature of the first reaction in step S1 is 40-150℃, and the first reaction time is 2-30h.

[0026] As preferred, step S1 is carried out under inert atmosphere.

[0027] As preferred, the mass of the free radical initiator added in step S2 is 0.1-10wt.% of the liquid metal-containing SiCN ceramic precursor B.

[0028] Further preferred, the free radical initiator is one or more of azobisisobutyronitrile, azobisisoheptyl nitrile, dibenzoyl peroxide, dodecanoyl peroxide, acetyl peroxide, tert-butyl peroxybenzoate, dicumyl peroxide, di-tert-butyl peroxide, persulfate.

[0029] If other components are added in step S2, the preparation process and the product will be changed.

[0030] As preferred, the temperature of the second reaction in step S3 is 50-300℃, and the second reaction time is 1-30h.

[0031] As preferred, step S3 is carried out under inert atmosphere, normal pressure, or under vacuum.

[0032] As preferred, the particle size of the metal-containing vinyl silazane powder D in step S3 is 1-100μm.

[0033] As preferred, the pressure of the cold isostatic pressing in step S4 is 50-200MPa, and the isostatic pressing time is 10-300s.

[0034] As preferred, the mass ratio of the metal-containing vinyl silazane powder D and the liquid metal-containing SiCN ceramic precursor B in step S4 is 100:(1-50).

[0035] Preferably, the third reaction in step S5 is carried out at a temperature of 800-1800℃ for 0.1-10h.

[0036] Further preferably, the third reaction in step S5 is carried out at a temperature of 1500-1800℃.

[0037] If the third reaction (sintering) is carried out at a temperature that is too low, the metal-containing vinylsilazane bulk E cannot complete the transition from organic to inorganic and from amorphous to crystalline phase; if the sintering temperature is too high, the metal-containing vinylsilazane bulk E cracks at the high temperature and cannot form a metal-based SiCN ceramic body with complete shape.

[0038] Preferably, the fourth reaction in step S6 is carried out at a temperature of 50-300℃ for 1-30h, and the fifth reaction is carried out at a temperature of 800-1800℃ for 0.1-10h.

[0039] Further preferably, the fourth reaction can be the same as the second reaction, and the fifth reaction can be the same as the third reaction.

[0040] Preferably, the impregnation time in step S6 is 1-2h.

[0041] Further preferably, the impregnation condition in step S6 is vacuum or gas pressure impregnation; when gas pressure impregnation is used, the pressure is 0.5-5MPa.

[0042] The pores of the metal-based SiCN ceramic body F are gradually filled by impregnation, and too many times of impregnation do not significantly change the pore filling of the metal-based SiCN ceramic body F and do not significantly affect the performance of the metal-based SiCN dense ceramic body product.

[0043] Preferably, the density of the metal-based SiCN ceramic body F in step S5 is 1.5-2.6g / cm 3 , and the density of the metal-based SiCN dense ceramic body G in step S7 is 1.9-3.9g / cm 3 .

[0044] Further preferably, the density of the metal-based SiCN dense ceramic body G is greater than the density of the metal-based SiCN ceramic body F.

[0045] Compared with the prior art, the present application has the following beneficial effects:

[0046] 1. The present application uses liquid vinylsilazane monomer and metal-based compound as raw materials to obtain liquid metal-containing vinylsilazane compound A, and a free radical initiator can be used to obtain liquid metal-containing SiCN ceramic precursor B; the preparation process of the liquid metal-containing SiCN ceramic precursor B is simple, it is not sensitive to air and water, and it can remain stable at room temperature for a long time.

[0047] 2、The application introduces different metal-based elements in the preparation process of the liquid metal-containing SiCN ceramic precursor B, which produces different effects; for example, introducing Al, La, Y and other metal-based elements into the liquid metal-containing SiCN ceramic precursor B can effectively inhibit the β-SiC grain coarsening in the subsequent high-temperature ceramic process, increase the density, and make it have higher high-temperature resistance; for example, introducing Ti, Zr, Fe and other metal-based elements into the liquid metal-containing SiCN ceramic precursor B can increase the final ceramic functional properties, such as reducing the resistivity of the ceramic, improving the dielectric loss, enhancing the wave absorption characteristics, etc., and broaden the application field.

[0048] 3、The liquid metal-containing SiCN ceramic precursor B prepared by directly mixing the liquid metal-containing vinylsilazane compound A with the free radical initiator is mixed with the metal-containing vinylsilazane powder D obtained after solidification and grinding of the liquid metal-containing SiCN ceramic precursor B in a certain proportion, the liquid metal-containing SiCN ceramic precursor B has a certain viscosity, which is beneficial to the die pressing forming of the metal-containing vinylsilazane powder D without adding other additives, and is beneficial to increasing the density and micro-morphology of the ceramic block after sintering.

[0049] 4、The metal-based SiCN ceramic body F is immersed in the liquid metal-containing SiCN ceramic precursor B, which can make the metal SiCN ceramic precursor penetrate into the pores of the metal-based SiCN ceramic body F, reduce the porosity of the metal-based SiCN ceramic body F, and further increase the density.

[0050] 5、The liquid metal-containing SiCN ceramic precursor B is used as raw material, the powder obtained after solidification and grinding is mixed with the original liquid metal-containing SiCN ceramic precursor B, and the metal-based SiCN ceramic body F is obtained after die pressing, cold isostatic pressing and sintering, then the high-density metal-based SiCN dense ceramic body G can be obtained through repeated immersion and multiple sintering under normal pressure; compared with the traditional hot pressing process or pressureless sintering process, the application can prepare large-size and complex-structure components without adding sintering aids, and the product composition is relatively pure. BRIEF DESCRIPTION OF DRAWINGS

[0051] Figure 1 The photos of the liquid metal-containing SiCN ceramic precursor B (LSiAlCN) and the solid metal-containing vinylsilazane gel C (SiAlCN) after solidification of the liquid metal-containing SiCN ceramic precursor B (LSiAlCN) prepared in Example 1 of the application.

[0052] Figure 2 The FTIR graph of the liquid metal-containing SiCN ceramic precursor B (LSiAlCN) and the solid metal-containing vinylsilazane gel C (SiAlCN) after solidification of the liquid metal-containing SiCN ceramic precursor B (LSiAlCN) prepared in Example 1 of the application.

[0053] Figure 3 Thermogravimetric curve of the solid metal-containing vinylsilazane gel C (SiAlCN) of Example 1 of the present application under Ar atmosphere.

[0054] Figure 4 Photo of the metal-based SiCN dense ceramic body G (Al-SiCN) prepared in Example 1 of the present application. DETAILED DESCRIPTION

[0055] The following are specific examples of the present application, which further describe the technical solutions of the present application, but the present application is not limited to these examples.

[0056] Unless otherwise specified, the materials used in the present application are conventional commercially available products, and the methods used are conventional technical means.

[0057] Example 1

[0058] S1, 18 g of tetramethyltetavinylcyclotetrasilazane and 2 g of isopropyl alcohol aluminum were sequentially added into a 100 ml three-necked flask, and the first reaction was carried out under N2 protection, the temperature was raised to 90°C and kept for 24 h, and tetramethyltetavinylcyclotetrasilazane aluminum A1 was obtained;

[0059] S2, 1 wt.% of azobisisobutyronitrile was added to the tetramethyltetavinylcyclotetrasilazane aluminum A1 and mixed uniformly to obtain a liquid aluminum-containing silazane precursor B1 (LSiAlCN);

[0060] S3, the liquid aluminum-containing silazane precursor B1 (LSiAlCN) was subjected to a second reaction, and was cured at 300°C for 1 h under Ar atmosphere to prepare an aluminum-containing polysilazane gel C1 (SiAlCN); the aluminum-containing polysilazane gel C1 (SiAlCN) was ball milled for 3 h, and passed through a 200 mesh standard sieve to obtain an aluminum-containing polysilazane powder D1 (SiAlCN powder);

[0061] S4, the aluminum-containing polysilazane powder D1 (SiAlCN powder) and the liquid aluminum-containing silazane precursor B1 (LSiAlCN) were mixed uniformly according to a mass ratio of 100:40, and then were molded, and after cold isostatic pressing treatment at 60 MPa for 120 s, a block E1 was obtained;

[0062] S5, the block E1 was subjected to a third reaction, and was heated to 1600°C and kept for 1 h under Ar atmosphere to prepare an aluminum-containing polysilazane ceramic body F1 (Al-SiCN body);

[0063] S6, the ceramic body F1 (Al-SiCN body) is immersed in the liquid aluminum-containing silicon carbon nitride alkane precursor B1 (LSiAlCN) for 1.5 hours in a vacuum environment, and after being taken out, a fourth reaction and a fifth reaction are sequentially performed; the fourth reaction is the same as the second reaction, and the fifth reaction can be the same as the third reaction;

[0064] S7, the step S6 is repeated for 3 times to obtain the aluminum-containing SiCN dense ceramic body G1 (Al-SiCN).

[0065] The photos of the liquid aluminum-containing silicon carbon nitride alkane precursor B1 (LSiAlCN) and the aluminum-containing polysilicon carbon nitride gel body C1 (SiAlCN) after curing are shown in Figure 1

[0066] The FTIR graphs of the two are shown in Figure 2 From Figure 2 It can be seen that the C=C peak at 1600 cm-1 is obviously reduced, indicating that the self-polymerization of the vinyl group occurs during the curing of the precursor B;

[0067] The thermal weight loss curve of the aluminum-containing polysilicon carbon nitride gel body C (SiAlCN) after curing under Ar atmosphere is shown in Figure 3 It can be seen that the ceramic yield at 1000℃ is about 70%;

[0068] Figure 4 The photo of the finally obtained aluminum-containing SiCN dense ceramic body G1 (Al-SiCN); the density of the aluminum-containing SiCN ceramic body G1 (Al-SiCN) is 3.19 g / cm 3

[0069] Example 2

[0070] S1, 18 g of tetramethyltetravinylcyclotetrasilazane and 2 g of iron isopropoxide are sequentially added into a 100 ml three-necked flask, and a first reaction is performed under N2 protection, the temperature is raised to 90℃ and kept for 30 hours to obtain tetramethyltetravinylcyclotetrasilazane iron A2;

[0071] S2, 1 wt.% of dicumyl peroxide is added to the tetramethyltetravinylcyclotetrasilazane iron A2 and mixed uniformly to obtain a liquid iron-containing silicon carbon nitride alkane precursor B2 (LSiFeCN);

[0072] S3, the liquid iron-containing silicon carbon nitride alkane precursor B2 (LSiFeCN) is subjected to a second reaction, and is cured at 300℃ for 1 hour under Ar atmosphere to obtain an iron-containing polysilicon carbon nitride gel body C2 (SiFeCN); the iron-containing polysilicon carbon nitride gel body C2 (SiFeCN) is ball milled for 5 hours, and is passed through a 200 mesh standard sieve to obtain an iron-containing polysilicon carbon nitride powder D2 (SiFeCN powder);​​

[0073] S4, the iron-containing polysilicon carbonitride powder D2 (SiFeCN powder) is mixed with the liquid iron-containing silicon carbonitride precursor B1 (LSiFeCN) uniformly according to a mass ratio of 100:30, and then is formed by molding, and after cold isostatic pressing treatment at 80 MPa for 120 s, a bulk body E2 is obtained;

[0074] S5, the bulk body E2 is subjected to a third reaction, is heated to 1700 DEG C under an Ar atmosphere and is kept for 1 h, and an iron-containing polysilicon carbonitride ceramic embryo F2 (Fe-SiCN embryo) is prepared;

[0075] S6, in a vacuum environment, the ceramic embryo F2 (Fe-SiCN embryo) is immersed in the liquid iron-containing silicon carbonitride precursor B2 (LSiFeCN) for 1.5 h, and after being taken out, is subjected to a fourth reaction and a fifth reaction in sequence; the fifth reaction is the same as the third reaction, and the fourth reaction is solidified at a temperature of 250 DEG C;

[0076] S7, the step S6 is repeated for 4 times, and an iron-containing SiCN dense ceramic body G2 (Fe-SiCN) is prepared.

[0077] The ceramic yield of the iron-containing polysilicon carbonitride gel body C2 (SiFeCN) at 1000 DEG C under an Ar atmosphere is 72% through thermal gravimetric analysis;

[0078] The density of the iron-containing SiCN ceramic bulk body G2 (Fe-SiCN) is 2.1 g / cm3 through Archimedes' density measurement method 3 .

[0079] Example 3

[0080] S1, 18 g of trimethyl trivinylcyclotrisilazane and 2 g of zirconium isopropoxide are sequentially added into a 100 ml three-necked flask, and a first reaction is carried out under N2 protection, and the temperature is raised to 100 DEG C and is kept for 15 h, and trimethyl trivinylcyclotrisilazane zirconium A3 is obtained;

[0081] S2, 1 wt.% of dibenzoyl peroxide is added into the trimethyl trivinylcyclotrisilazane zirconium A3 and is uniformly mixed, and a liquid zirconium-containing silicon carbonitride precursor B3 (LSiZrCN) is obtained;

[0082] S3, the liquid zirconium-containing silicon carbonitride precursor B3 (LSiZrCN) is subjected to a second reaction, is heated to 250 DEG C under an Ar atmosphere and is solidified for 1 h, and an iron-containing polysilicon carbonitride gel body C3 (SiZrCN) is prepared; the iron-containing polysilicon carbonitride gel body C3 (SiZrCN) is ball milled for 6 h, and is passed through a 200 mesh standard sieve, and an iron-containing polysilicon carbonitride powder D3 (SiZrCN powder) is obtained;

[0083] S4, the zirconium-containing polysilicon carbonitride powder D3 (SiZrCN powder) and the liquid zirconium-containing silicon carbonitride precursor B1 (LSiZrCN) are mixed uniformly at a mass ratio of 100:40, then are molded, and after cold isostatic pressing at 100 MPa for 180 s, a bulk body E3 is obtained;

[0084] S5, the bulk body E3 is subjected to a third reaction, is heated to 1500°C under an argon atmosphere and is kept at 1500°C for 1 h, and a zirconium-containing polysilicon carbonitride ceramic body F3 (Zr-SiCN body) is prepared;

[0085] S6, the ceramic body F3 (Zr-SiCN body) is immersed in the liquid zirconium-containing silicon carbonitride precursor B3 (LSiZrCN) at 1 MPa for 1.5 h, and after being taken out, is subjected to a fourth reaction and a fifth reaction in sequence; the fourth reaction is the same as the second reaction, and the fifth reaction can be the same as the third reaction;

[0086] S7, the step S6 is repeated for 3 times, and a zirconium-containing SiCN dense ceramic body G3 (Zr-SiCN) is prepared.

[0087] The ceramic yield of the zirconium-containing polysilicon carbonitride gel body C3 (SiZrCN) at 1000°C under an argon atmosphere is 70% through thermogravimetric analysis;

[0088] The density of the zirconium-containing SiCN ceramic bulk body G3 (Zr-SiCN) is 2.5 g / cm 3 .

[0089] Example 4

[0090] S1, 25 g of trimethyltrivinylcyclotrisilazane and 3 g of lanthanum acetylacetonate are sequentially added into a 100 ml three-necked flask, a first reaction is carried out under N2 protection, the temperature is raised to 85°C and is kept at 85°C for 10 h, and trimethyltrivinylcyclotrisilazane lanthanum A4 is obtained;

[0091] S2, 0.5 wt.% of dicumyl peroxide is added into the trimethyltrivinylcyclotrisilazane lanthanum A4 and is uniformly mixed, and a liquid lanthanum-containing silicon carbonitride precursor B4 (LSiLaCN) is obtained;

[0092] S3, the liquid lanthanum-containing silicon carbonitride precursor B4 (LSiLaCN) is subjected to a second reaction, is heated to 280°C under an argon atmosphere and is kept at 280°C for 5 h, and a lanthanum-containing polysilicon carbonitride gel body C4 (SiLaCN) is prepared; the lanthanum-containing polysilicon carbonitride gel body C4 (SiLaCN) is ball milled for 6 h, is passed through a 200 mesh standard sieve, and a lanthanum-containing polysilicon carbonitride powder D4 (SiLaCN powder) is obtained;

[0093] S4, the lanthanum-containing polysilicocarbodiitane powder D4 (SiLaCN powder) and the liquid lanthanum-containing silicocarbodiitane precursor B1 (LSiLaCN) are mixed uniformly at a mass ratio of 100:30, and then are molded, and after cold isostatic pressing at 70 MPa for 120 s, a block E4 is obtained;

[0094] S5, the block E4 is subjected to a third reaction, is heated to 1800°C under an argon atmosphere and is kept at 1800°C for 1 h, and a lanthanum-containing polysilicocarbodiitane ceramic body F4 (La-SiCN body) is prepared;

[0095] S6, the ceramic body F4 (La-SiCN body) is immersed in the liquid lanthanum-containing silicocarbodiitane precursor B4 (LSiLaCN) at 1.5 MPa for 1.5 h, and after being taken out, is subjected to a fourth reaction and a fifth reaction in sequence; the fourth reaction is the same as the second reaction, and the fifth reaction can be the same as the third reaction;

[0096] S7, the step S6 is repeated for 3 times, and a lanthanum-containing SiCN dense ceramic body G4 (La-SiCN) is prepared.

[0097] The ceramic yield of the lanthanum-containing polysilicocarbodiitane gel C4 (SiLaCN) at 1000°C under an argon atmosphere is 75% through thermogravimetric analysis;

[0098] The density of the lanthanum-containing SiCN ceramic block G4 (La-SiCN) is 3.2 g / cm3 through Archimedes' density measurement method 3 .

[0099] Example 5

[0100] S1, 20 g of tetramethyltetravinylcyclotetrasilazane and 3 g of isopropyl beryllium are sequentially added into a 100 ml three-necked flask, and a first reaction is carried out under N2 protection, the temperature is raised to 90°C and is kept at 90°C for 20 h, and a tetramethyltetravinylcyclotetrasilazane beryllium A5 is obtained;

[0101] S2, 0.8 wt.% of azobisisobutyronitrile is added into the tetramethyltetravinylcyclotetrasilazane beryllium A5 and is mixed uniformly, and a liquid beryllium-containing silicocarbodiitane precursor B5 (LSiBeCN) is obtained;

[0102] S3, the liquid beryllium-containing silicocarbodiitane precursor B5 (LSiBeCN) is subjected to a second reaction, is heated to 250°C under an argon atmosphere and is kept at 250°C for 1 h, and a beryllium-containing polysilicocarbodiitane gel C5 (SiBeCN) is prepared; the beryllium-containing polysilicocarbodiitane gel C5 (SiBeCN) is ball milled for 5 h, is passed through a 200 mesh standard sieve, and a beryllium-containing polysilicocarbodiitane powder D5 (SiBeCN powder) is obtained;

[0103] S4, the beryllium-containing polysilicon carbon nitride powder D5 (SiBeCN powder) and the liquid beryllium-containing silicon carbon nitride precursor B1 (LSiBeCN) are mixed uniformly at a mass ratio of 100:20, then molded, and after cold isostatic pressing at 80 MPa for 120 s, a block E5 is obtained;

[0104] S5, the block E5 is subjected to a third reaction, heated to 1600°C under an argon atmosphere and kept for 1 h, to obtain a beryllium-containing polysilicon carbon nitride ceramic body F5 (Be-SiCN body);

[0105] S6, the ceramic body F5 (Be-SiCN body) is immersed in the liquid beryllium-containing silicon carbon nitride precursor B5 (LSiBeCN) at 1 MPa for 1.5 h, and after being taken out, is subjected to a fourth reaction and a fifth reaction in sequence; the fifth reaction is the same as the third reaction, and the fourth reaction is solidified at a temperature of 300°C;

[0106] S7, the step S6 is repeated 4 times to obtain a beryllium-containing SiCN dense ceramic body G5 (Be-SiCN).

[0107] The ceramic yield of the beryllium-containing polysilicon carbon nitride gel C5 (SiBeCN) at 1000°C under an argon atmosphere is 78% by thermogravimetric analysis;

[0108] The density of the beryllium-containing SiCN ceramic block G5 (Be-SiCN) is 2.2 g / cm3 by Archimedes' density measurement method. 3 .

[0109] Example 6

[0110] S1, 30 g of tetramethyltetravinylcyclotetrasilazane and 4 g of yttrium acetylacetonate are sequentially added to a 100 ml three-necked flask, and a first reaction is carried out under N2 protection, heated to 60°C and kept for 10 h to obtain tetramethyltetravinylcyclotetrasilazane yttrium A6;

[0111] S2, 0.5 wt.% of dicumyl peroxide is added to the tetramethyltetravinylcyclotetrasilazane yttrium A6 and mixed uniformly to obtain a liquid yttrium-containing silicon carbon nitride precursor B6 (LSiYCN);

[0112] S3, the liquid yttrium-containing silicon carbon nitride precursor B6 (LSiYCN) is subjected to a second reaction, solidified at 300°C under an argon atmosphere for 5 h to obtain a yttrium-containing polysilicon carbon nitride gel C6 (SiYCN); the yttrium-containing polysilicon carbon nitride gel C6 (SiYCN) is ball milled for 10 h and sieved through a 200 mesh standard sieve to obtain a yttrium-containing polysilicon carbon nitride powder D6 (SiYCN powder);

[0113] S4, the yttrium-containing polysilicon carbonitride powder D6 (SiYCN powder) and the liquid yttrium-containing silicon carbonitride precursor B1 (LSiYCN) were mixed uniformly at a mass ratio of 100:10, and then were molded and formed, and after cold isostatic pressing at 60 MPa for 120 s, a block E6 was obtained;

[0114] S5, the block E6 was subjected to a third reaction, and was heated to 1500℃ under an argon atmosphere and was kept for 1 h, to obtain a yttrium-containing polysilicon carbonitride ceramic body F6 (Y-SiCN body);

[0115] S6, the ceramic body F6 (Y-SiCN body) was immersed in the liquid yttrium-containing silicon carbonitride precursor B6 (LSiYCN) at 1.5 MPa for 1.5 h, and after being taken out, was subjected to a fourth reaction and a fifth reaction in sequence; the fourth reaction was the same as the second reaction, and the fifth reaction was the same as the third reaction;

[0116] S7, the step S6 was repeated for 5 times, to obtain a yttrium-containing SiCN dense ceramic body G6 (Y-SiCN).

[0117] The ceramic yield of the yttrium-containing polysilicon carbonitride gel C6 (SiYCN) at 1000℃ under an argon atmosphere was 73% by thermogravimetric analysis;

[0118] The density of the yttrium-containing SiCN ceramic block G6 (Y-SiCN) was 3.18 g / cm3 by Archimedes' density measurement method. 3 .

[0119] Example 7

[0120] Compared with Example 1, the difference is that in S4, the aluminum-containing polysilicon carbonitride powder D1 (SiAlCN powder) and the liquid aluminum-containing silicon carbonitride precursor B1 (LSiAlCN) were mixed uniformly at a mass ratio of 100:20, and then were molded and formed and cold isostatic pressed, to obtain a block E7; the remaining steps were the same.

[0121] The density of the aluminum-containing SiCN ceramic block G7 (Al-SiCN) was 2.85 g / cm3 by Archimedes' density measurement method. 3 .

[0122] It can be seen that only by changing the mixing ratio of the metal-containing vinylsilazane powder D and the liquid metal-containing SiCN ceramic precursor B, within a certain range, when the content of the liquid metal-containing SiCN ceramic precursor B is reduced, the density of the metal-based SiCN dense ceramic body will decrease accordingly.

[0123] Example 8

[0124] Compared with Example 1, the difference lies in that, in S5, the block E1 is subjected to a third reaction, and is heated to 1800℃ under Ar atmosphere and kept for 1h to obtain an aluminum-containing polysilicon carbonitride ceramic embryo F8 (Al-SiCN embryo); and the rest of the steps are the same.

[0125] The density of the aluminum-containing SiCN ceramic block G8 (Al-SiCN) is 3.3g / cm 3 .

[0126] It can be seen that, within a certain range, increasing the sintering temperature can increase the density of the metal-based SiCN dense ceramic body.

[0127] Example 9

[0128] Compared with Example 1, the difference lies in that the fourth reaction is different from the second reaction, and the fifth reaction can be different from the third reaction; the second reaction temperature is 300℃, the third reaction temperature is 1600℃, the fourth reaction temperature is 280℃, and the fifth reaction temperature is 1700℃.

[0129] The density of the aluminum-containing SiCN ceramic block G9 (Al-SiCN) is 3.27g / cm 3 .

[0130] It can be seen that, within the scope of the present application, different sintering temperatures can affect the density of the dense ceramic body, but different solidification temperatures have little effect on the density of the ceramic body.

[0131] Example 10

[0132] Compared with Example 1, the difference lies in that, in S3, the aluminum-containing polysilicon carbonitride gel C1 (SiAlCN) is ball milled and then sieved through a 100-mesh standard sieve to obtain aluminum-containing polysilicon carbonitride powder D10 (SiAlCN powder); and the rest of the steps are the same.

[0133] The density of the aluminum-containing SiCN ceramic block G8 (Al-SiCN) is 2.6g / cm 3 .

[0134] It can be seen that, the particle size of the metal-containing vinylsilazane powder is too large to affect the density of the metal-based SiCN dense ceramic body.

[0135] Comparative Example 1

[0136] Compared with Example 1, the difference lies in that, in S4, the aluminum-containing polysilicon carbonitride powder D1 (SiAlCN powder) is directly molded and formed, and after being cold isostatic pressed at 60MPa for 120s, the block E11 is obtained; and the rest of the steps are the same.

[0137] The density of the Al-containing SiCN ceramic bulk G11 (Al-SiCN) is 1.53 g / cm 3 .

[0138] In the present comparative example, no liquid Al-containing SiCN precursor B1 is added, which results in a significant decrease in the density of the metal-based SiCN dense ceramic body.

[0139] Comparative Example 2

[0140] Compared with Example 1, the difference is that in S4, the Al-containing polysilicon carbonitride powder D1 (SiAlCN powder) is uniformly mixed with the liquid Al-containing SiCN precursor B1 (LSiAlCN) at a mass ratio of 100:60, and then is formed by molding, and then is treated by cold isostatic pressing at 60 MPa for 120 s to obtain the bulk E12; the remaining steps are the same.

[0141] The density of the Al-containing SiCN ceramic bulk G12 (Al-SiCN) is 2.07 g / cm 3 .

[0142] In the present comparative example, although the addition of too much liquid Al-containing SiCN precursor B1 plays a role as a binder, too much liquid will make the bulk obtained by molding very loose, and the solidification and sintering process will leave a large number of pores in the bulk, which will affect the density of the metal-based SiCN ceramic body.

[0143] In summary, in the present application, the liquid metal-containing SiCN ceramic precursor B is used as a raw material, and after solidification and grinding, the obtained powder is mixed with the original liquid metal-containing SiCN ceramic precursor B, and then is formed by molding and cold isostatic pressing, and then is sintered to obtain the metal-based SiCN ceramic body F, and then the high-density metal-based SiCN dense ceramic body G can be obtained by repeated impregnation and multiple sintering under normal pressure; compared with the traditional hot pressing process or pressureless sintering process, the present application does not need to add sintering aids, and can prepare large-size and complex-structure components, and the product composition is relatively pure.

[0144] The specific embodiments described herein merely exemplify the spirit of the present application. Those skilled in the art to which the present application belongs can make various modifications or supplements to the described specific embodiments or use similar ways to replace them, without deviating from the spirit of the present application or exceeding the scope defined by the appended claims.

Claims

1. A method for producing a metal-based SiCN dense ceramic body, characterized in that, The preparation method comprises: S1, using liquid vinyl silazane monomer and metal-based compound as raw materials, performing first reaction to obtain liquid metal-containing vinyl silazane compound A; The mass ratio of the vinyl silazane monomer and the metal-based compound is 100:(0.1-50); The metal-based compound is one or more of acetylacetone metal salt, metal alkoxide and metallocene compound; S2, mixing the liquid metal-containing vinyl silazane compound A with a free radical initiator to obtain liquid metal-containing SiCN ceramic precursor B; The free radical initiator is added in an amount of 0.1-10wt.% of the liquid metal-containing SiCN ceramic precursor B; The free radical initiator is one or more of azobisisobutyronitrile, azobisisoheptyl nitrile, dibenzoyl peroxide, diperazelaoyl, acetyl peroxide, tert-butyl peroxybenzoate, dicumyl peroxide, di-tert-butyl peroxide and persulfate; S3, performing second reaction on the liquid metal-containing SiCN ceramic precursor B to obtain solid metal-containing vinyl silazane gel C; grinding the solid metal-containing vinyl silazane gel C to obtain metal-containing vinyl silazane powder D; S4, mixing the metal-containing vinyl silazane powder D with the liquid metal-containing SiCN ceramic precursor B, and then performing die molding and cold isostatic pressing to obtain metal-containing vinyl silazane bulk E; The mass ratio of the metal-containing vinyl silazane powder D and the liquid metal-containing SiCN ceramic precursor B is 100:(1-50); S5, performing third reaction on the metal-containing vinyl silazane bulk E to obtain metal-based SiCN ceramic body F; S6, immersing the metal-based SiCN ceramic body F in the liquid metal-containing SiCN ceramic precursor B, and then sequentially performing fourth reaction and fifth reaction; the temperature of the fourth reaction is 50-300℃, and the fourth reaction time is 1-30h; the temperature of the fifth reaction is 800-1800℃, and the fifth reaction time is 0.1-10h; S7, repeating the step S6 for 1-6 times to obtain metal-based SiCN dense ceramic body G.

2. The production method according to claim 1, characterized by, The temperature of the first reaction in the step S1 is 40-150℃, and the first reaction time is 2-30h.

3. The preparation method according to claim 1, characterized in that, The particle size of the metal-containing vinyl silazane powder D in the step S3 is 1-100μm.

4. The preparation method according to claim 1, characterized in that, The temperature of the second reaction in the step S3 is 50-300℃, and the second reaction time is 1-30h.

5. The preparation method according to claim 1, characterized in that, The pressure of the cold isostatic pressing in the step S4 is 50-200MPa, and the static pressure time is 10-300s.

6. The method of claim 1, wherein, The temperature of the third reaction in the step S5 is 800-1800℃, and the third reaction time is 0.1-10h.

7. The preparation method according to claim 1, characterized in that, The density of the metal-based SiCN ceramic body F in the step S5 is 1.5-2.6 g / cm 3 ; and the density of the metal-based SiCN dense ceramic body G in the step S7 is 1.9-3.9 g / cm 3 .

8. The production method according to claim 7, characterized by, The density of the metal-based SiCN dense ceramic body G is greater than the density of the metal-based SiCN ceramic body F.

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