High temperature resistant ceramic binder, its preparation method and application

Abstract

The application belongs to the technical field of ceramic connection, and particularly relates to a high-temperature-resistant ceramic adhesive as well as a preparation method and application thereof. The preparation method of the high-temperature-resistant ceramic adhesive comprises the following steps: (1) adding a coupling agent into a mixed solution of ethanol and deionized water to prepare a coupling agent aqueous solution; (2) adding fillers into the coupling agent aqueous solution to activate and dry the fillers; (3) adding a dispersing agent and a thermal initiator into polysilazane to obtain a polysilazane solution; and (4) adding the dried fillers in step (2) into the polysilazane solution, and stirring uniformly to prepare the high-temperature-resistant ceramic adhesive. The high-temperature-resistant ceramic adhesive is applied to the bonding of Si3N4 ceramic blocks. The ceramic adhesive has excellent temperature resistance, high mechanical properties and low shrinkage. The interface between the ceramic adhesive and Si3N4 ceramic can form a dense reaction layer through element diffusion, and the ceramic adhesive has good adhesion to Si3N4 ceramic.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of ceramic connection, and particularly relates to a high-temperature-resistant ceramic adhesive as well as a preparation method and application thereof. BACKGROUND

[0002] Ceramic materials have unique comprehensive properties such as high hardness, high strength, high temperature resistance, oxidation resistance, wear resistance and corrosion resistance, and are the core strategic materials in the field of modern high-end equipment manufacturing. In the high-end fields of aerospace, aviation, military and medical treatment, the irreplaceability of ceramic materials is increasingly highlighted. The demand for large-size and complex-structure ceramic parts is increasing year by year, but it is difficult to directly prepare complex-shaped ceramic parts due to the low ductility and high brittleness of ceramic materials. Therefore, ceramic connection technology which can realize the combination of ceramic materials with different shapes has attracted extensive attention of researchers, and how to improve the connection reliability between ceramic materials has become a bottleneck restricting the size, structure and other parameters of ceramic parts.

[0003] Chinese patent CN110563468A discloses a high-strength ceramic adhesive, which utilizes solid-phase diffusion technology to form a dense alloy structure inside the adhesive, thereby improving the fatigue resistance and impact resistance of the adherend. However, solid-phase diffusion connection relies on the interfacial migration mechanism of atoms in the material, and the realization of this process requires specific temperature and pressure. Chinese patent CN119820029A, Chinese patent CN119430983A and Chinese patent CN119634862A all disclose methods for hetero-connection of ceramic and metal by brazing technology, and the connections all have high mechanical connection strength, but the brazing connection technology has a relatively complex processing process.

[0004] In contrast, the adhesive bonding ceramic technology has the advantages of small part deformation, uniform stress distribution, good connection effect for heterogeneous materials, simple process, no need for strict control of temperature and pressure, etc. The adhesive bonding ceramic technology is divided into inorganic adhesive bonding ceramic and organic adhesive bonding ceramic. Although the inorganic adhesive bonding ceramic has the advantages of low price, economic and environmental protection, and good high and low temperature resistance, it has poor acid and alkali resistance and water resistance, and low average bonding strength, thus limiting its application in high-precision fields such as aerospace and military. The organic adhesive bonding ceramic refers to a kind of adhesive with an organic polymer as a matrix, which can maintain a certain bonding strength at high temperature, and has the advantages of good toughness, strong adhesion and good impact resistance. The organic adhesive includes polyurethane, polyimide and phenolic resin. The polyurethane adhesive contains isocyanate and carbamate groups with strong polarity and high chemical activity, and can easily form hydrogen bonds with the adherend, thus having good chemical adhesion with ceramics, metals and glass. However, most polyurethane has poor high temperature resistance. The polyimide adhesive has good water resistance, organic reagent resistance and high temperature resistance, but has the disadvantages of complex bonding process, high curing temperature / pressure and difficult storage. The phenolic resin is a kind of organic adhesive developed early and used in large quantities, which can form a thick graphite layer and carbon layer after pyrolysis, but has high requirements for equipment and process conditions. The defects of the above adhesives to a large extent limit the popularization and application of the bonding system in ceramic materials. Therefore, the design of the adhesive system and the interface control to realize the intrinsic strengthening of the ceramic connecting structure is an important way to promote the large-scale engineering application of large-size and complex structure ceramic parts. SUMMARY

[0005] In view of the deficiencies of the prior art, the purpose of the present application is to provide a high-temperature-resistant ceramic adhesive, which has excellent temperature resistance and high mechanical properties, and low shrinkage rate; the interface between the ceramic adhesive and Si3N4 ceramic can form a dense reaction layer through element diffusion, and has good adhesion to Si3N4 ceramic.

[0006] Another purpose of the present application is to provide a preparation method and application of the high-temperature-resistant ceramic adhesive.

[0007] The preparation method of the high-temperature-resistant ceramic adhesive comprises the following steps:

[0008] (1) The coupling agent is added to a mixed solution of ethanol and deionized water, and hydrolysis is carried out by stirring to obtain a coupling agent aqueous solution;

[0009] (2) The filler is added to the coupling agent aqueous solution, and after stirring treatment, the filler is dried;

[0010] (3) adding dispersant and thermal initiator into polysilazane, stirring uniformly to obtain polysilazane solution;

[0011] (4) adding the filler dried in step (2) into the polysilazane solution, stirring uniformly, the filler is uniformly dispersed in the polysilazane solution, to obtain the high-temperature-resistant ceramic binder;

[0012] The high-temperature-resistant ceramic binder is applied to the bonding of Si3N4 ceramic block, and the bonding process needs to be treated by two steps of heat curing and high-temperature sintering.

[0013] When the high-temperature sintering treatment is carried out in an air atmosphere, the selected filler is B4C, ZrB2 and SiC w ; when the high-temperature sintering treatment is carried out in a nitrogen atmosphere, the selected filler is B4C, ZrB2, ZrSi2 and SiC w ; the D50 particle size of B4C, ZrB2, SiC w and ZrSi2 is 0.5 μm.

[0014] In step (1), the coupling agent is KH-550, the stirring speed is 300-500 rpm, and the stirring time is 30-50 min.

[0015] The mass ratio of ethanol to deionized water is (9-10):1.

[0016] In step (2), the amount of the coupling agent added is 1-2 wt.% of the total amount of the filler; the stirring speed is 300-500 rpm, the stirring time is 30-50 min; the drying temperature is 80°C, and the drying time is 2 h.

[0017] In step (3), the dispersant is BYK-2070 or KOS-110, the thermal initiator is dicumyl peroxide, and the structure of the polysilazane is as follows:

[0018] ;

[0019] In the formula, n is the number of repeating units in the polymer.

[0020] The amount of the thermal initiator added is 2-4 wt.% of the total amount of the polysilazane; the amount of the polysilazane added is 30-60 wt.% of the total amount of the coupling agent, the filler, the dispersant, the thermal initiator and the polysilazane; and the amount of the dispersant added is 10-20 wt.% of the total amount of the filler.

[0021] In step (3), the stirring speed is 300-500 rpm, and the stirring time is 10-30 min; in step (4), the stirring speed is 300-500 rpm, and the stirring time is 2-3 h.

[0022] The preparation method of the high-temperature-resistant ceramic adhesive, when the high-temperature-resistant ceramic adhesive is applied in air atmosphere, the raw materials selected include, by mass percentage: 8-32wt.% of B4C, 30wt.% of ZrB2, 8-32wt.% of SiC w and 30-60wt.% of polysilazane; when applied in nitrogen atmosphere, the raw materials selected include, by mass percentage: 34-36wt.% of B4C, 2-9.2wt.% of ZrB2, 7-12wt.% of ZrSi2, 6-7.2wt.% of SiC w and 40-50wt.% of polysilazane.

[0023] The high-temperature-resistant ceramic adhesive is prepared by the preparation method of the high-temperature-resistant ceramic adhesive.

[0024] The application of the high-temperature-resistant ceramic adhesive is applied to the bonding of Si3N4 ceramic blocks.

[0025] The bonding method of the Si3N4 ceramic block comprises the following steps:

[0026] 1) Under the conditions of temperature 25-30℃ and humidity 30-40%, the high-temperature-resistant ceramic adhesive is uniformly brushed on the contact surfaces of the two Si3N4 ceramic blocks to be bonded by double-sided gluing, the brushing thickness is 100-200μm, after standing for 5min, the two surfaces coated with the high-temperature-resistant ceramic adhesive are pasted together to realize preliminary bonding;

[0027] 2) The sample after preliminary bonding in step 1) is subjected to heat curing treatment: the temperature is raised to 79-81℃ at a rate of 4-5℃ / min and kept for 115-125min; then the temperature is gradually raised to 95-105℃, 115-125℃, 135-145℃, 155-165℃, 175-185℃ at a rate of 2-3℃ / min, and kept for 115-125min at each temperature point, after curing, the temperature is cooled to room temperature at a rate of 4-5℃ / min;

[0028] 3) The sample after curing in step 2) is put into a tube furnace and subjected to high-temperature sintering treatment in air or nitrogen atmosphere: the temperature is raised to 195-205℃ at a rate of 4-5℃ / min and kept for 55-65min; then the temperature is gradually raised to 395-405℃, 595-605℃, 795-805℃, 1095-1105℃ at a rate of 2-3℃ / min, and kept for 55-65min at each temperature point, finally the temperature is cooled to room temperature at a rate of 4-5℃ / min, to complete the bonding of the Si3N4 ceramic block.

[0029] Compared with the prior art, the application has the following advantages:

[0030] (1) The polysilazane used in the application is an organic silicon precursor resin, which is an organic-inorganic hybrid polymer between organic and inorganic. The precursor resin exists in an organic state at room temperature and can realize dynamic evolution from organic to inorganic through thermal induction. The precursor resin has double characteristics of organic and inorganic, can fill the performance gap of traditional adhesives in high-temperature applications, has great research value in the fields of connection of ceramic matrix composites and protection in extreme environments, and also provides more ideas for preparation of large-size and complex-structure ceramic parts;

[0031] (2) The high-temperature-resistant ceramic adhesive prepared in the application can generate part of inorganic glass phase at high temperature. The inorganic glass phase and the inert filler in the adhesive that does not generate glass phase form a dense structure together. At the same time, a reaction layer is formed between the adhesive and the Si3N4 ceramic block due to element mutual diffusion, and intermolecular bonding is generated. The joint action of the two aspects can promote good bonding of the adhesive and the ceramic material;

[0032] (3) The high-temperature-resistant ceramic adhesive prepared in the application has good temperature resistance, density, toughness and other physical properties. By adjusting the ratio of raw materials, ceramic adhesives meeting different performance requirements can be prepared. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 It is a schematic diagram of the bonding mode of the Si3N4 ceramic block in the examples and comparative examples.

[0034] In the figure: 1, Si3N4 ceramic block; 2, ceramic adhesive.

[0035] Figure 2 It is an infrared spectrum of polysilazane.

[0036] Figure 3 It is a nuclear magnetic hydrogen spectrum of polysilazane.

[0037] Figure 4 It is a molecular weight distribution diagram of polysilazane. DETAILED DESCRIPTION

[0038] The application will be further described below in combination with examples.

[0039] The raw materials used in the examples and comparative examples are all conventional commercially available raw materials unless otherwise specified. The process methods used in the examples and comparative examples are all conventional methods in the art unless otherwise specified.

[0040] Some of the raw materials used in the examples and comparative examples are described as follows:

[0041] BYK-2070, purchased from Germany BYK Chemical;

[0042] KOS-110, purchased from Guangzhou Kangou Shuang Trading Co., Ltd.

[0043] Ethanol, analytical grade;

[0044] B4C, ZrB2, SiC w The D50 particle size of ZrSi2, SiO2 and ZrO2 is 0.5 μm;

[0045] Polysilazane, purchased from Anzhi Electronic Materials Co., Ltd.; Figures 2-4 The images show the infrared spectrum, the 1H NMR spectrum, and the molecular weight distribution of polysilazane, respectively. Figure 2 As can be seen from this, polysilazane at 1278cm -1 and 2980cm -1 Carbon-carbon double bonds appear at 2000-2250 cm⁻¹. -1 The presence of silane-hydrogen bonds indicates that the polysilazane contains a large number of active groups. From... Figure 3 It can be seen that Si-H and Si-CH=CH2 active groups exist on polysilazane with a chemical shift between 4 and 7 ppm. (From...) Figure 2 and Figure 3 It can be seen that polysilazane contains a large number of active groups, which facilitates its addition reaction at high temperatures, reduces the escape of small molecules, and improves the thermal stability of the final product. Figure 4 It can be seen that polysilazane has only one single peak, and its number-average molecular weight M n Weight-average molecular weight M w The polydispersity index (D) was 620 g / mol, 622 g / mol, and 1.003, respectively, indicating that the polysilazane has a narrow molecular weight distribution and relatively uniform properties, which improves the storage stability of the final ceramic binder.

[0046] The bonding method of the Si3N4 ceramic blocks in the embodiments and comparative examples is as follows. Figure 1 As shown, ceramic adhesive 2 is applied to the contact surfaces of the two Si3N4 ceramic blocks 1 to be bonded, and then the parts coated with ceramic adhesive 2 are put together to achieve initial bonding.

[0047] Example 1

[0048] The preparation method of the high-temperature resistant ceramic adhesive includes the following steps:

[0049] (1) At room temperature, 0.5g of KH-550 was added to a mixed solution of 45g of ethanol and 5g of deionized water, and the mixture was stirred at 500rpm for 30min to hydrolyze the coupling agent to obtain an aqueous solution.

[0050] (2) 50 g of the filler (10 g of B4C, 30 g of ZrB2, 10 g of SiC w ) was added into the coupling agent aqueous solution, stirred for 30 min at 500 rpm, and then dried in a blast drying oven at 80 °C for 2 h;

[0051] (3) 5 g of BYK-2070 and 1 g of dicumyl peroxide were added into 50 g of polysilazane, stirred for 10 min at 500 rpm to obtain a polysilazane solution;

[0052] (4) The dried filler in step (2) was added into the polysilazane solution, stirred for 2 h at 500 rpm to prepare a high-temperature-resistant ceramic adhesive.

[0053] The high-temperature-resistant ceramic adhesive is applied to the bonding of Si3N4 ceramic blocks.

[0054] The bonding method of the Si3N4 ceramic block comprises the following steps:

[0055] 1) The Si3N4 ceramic block was placed in ethanol and ultrasonicated for 30 min, then taken out and dried in an oven at 60 °C for 2 h. After being taken out, the two Si3N4 ceramic blocks (30 mm x 10 mm x 5 mm) to be bonded were placed in contact with each other, and the high-temperature-resistant ceramic adhesive was evenly applied on the contact surfaces of the two blocks by double-sided coating, with a thickness of 120 μm and an area of 10 mm x 10 mm. After standing for 5 min, the two blocks were bonded together to achieve preliminary bonding. Figure 1

[0056] 2) The sample after preliminary bonding in step 1) was placed in a vacuum drying oven for heat curing treatment: the temperature was increased to 80 °C at a rate of 4 °C / min and kept for 120 min; then the temperature was gradually increased to 100 °C, 120 °C, 140 °C, 160 °C and 180 °C at a rate of 2 °C / min, and kept for 120 min at each temperature point; after curing, the temperature was cooled to room temperature at a rate of 5 °C / min;

[0057] 3) The sample after curing in step 2) was placed in an Al2O3 tube furnace for high-temperature sintering treatment in air: the temperature was increased to 200 °C at a rate of 5 °C / min and kept for 60 min; then the temperature was gradually increased to 400 °C, 600 °C, 800 °C and 1100 °C at a rate of 2 °C / min, and kept for 60 min at each temperature point, and finally cooled to room temperature at a rate of 5 °C / min, to complete the bonding of the Si3N4 ceramic block.

[0058] Example 2 ​

[0059] The preparation method of the high-temperature-resistant ceramic binder comprises the following steps:

[0060] (1) At room temperature, 2 g of KH-550 is added to a mixed solution of 100 g of ethanol and 10 g of deionized water, and hydrolysis is carried out under the condition of 400 rpm for 40 min to prepare a coupling agent aqueous solution;

[0061] (2) 100 g of fillers (68 g of B4C, 6 g of ZrB2, 12 g of SiC w , and 14 g of ZrSi2) are added to the coupling agent aqueous solution, and after stirring treatment under the condition of 500 rpm for 30 min, they are placed in a blast drying oven and dried at 80℃ for 2 h;

[0062] (3) 15 g of BYK-2070 and 3 g of dicumyl peroxide are added to 100 g of polysilazane, and stirring is carried out under the condition of 500 rpm for 10 min to obtain a polysilazane solution;

[0063] (4) The dried fillers in step (2) are added to the polysilazane solution, and stirring is carried out under the condition of 500 rpm for 2 h to prepare a high-temperature-resistant ceramic binder.

[0064] The application of the high-temperature-resistant ceramic binder is applied to the bonding of Si3N4 ceramic blocks.

[0065] The bonding method of the Si3N4 ceramic block comprises the following steps:

[0066] 1) The Si3N4 ceramic block is placed in ethanol and ultrasonically treated for 30 min, taken out and dried in an oven at 60℃ for 2 h, and after taking out, under the condition of a temperature of 30℃ and a humidity of 35%, a double-sided gluing method is used to uniformly apply the high-temperature-resistant ceramic binder on the contact surfaces of the two Si3N4 ceramic blocks (30 mm x 10 mm x 5 mm) to be bonded, the thickness of the coating is 150 μm, the coating area is 10 mm x 10 mm, and after standing for 5 min, the two surfaces coated with the high-temperature-resistant ceramic binder are adhered together according to the manner shown in Figure 1 , to realize preliminary bonding;

[0067] 2) The sample after preliminary bonding in step 1) is placed in a vacuum drying oven for heat curing treatment: the temperature is raised to 80℃ at a rate of 4℃ / min and kept for 120 min; then the temperature is gradually raised to 100℃, 120℃, 140℃, 160℃ and 180℃ at a rate of 2℃ / min, and kept for 120 min at each temperature point; and after curing, the temperature is cooled to room temperature at a rate of 5℃ / min;

[0068] 3) Put the sample solidified in step 2) into an Al2O3 tube furnace, and perform high-temperature sintering treatment under a nitrogen atmosphere: heat to 200℃ at a rate of 5℃ / min and keep for 60min; then gradually heat to 400℃, 600℃, 800℃, 1100℃ at a rate of 2℃ / min, and keep for 60min at each temperature point, and finally cool to room temperature at a rate of 5℃ / min, to complete the bonding of the Si3N4 ceramic block.

[0069] Example 3

[0070] The preparation method of the high-temperature-resistant ceramic adhesive comprises the following steps:

[0071] (1) At room temperature, 0.9g of KH-550 is added to a mixed solution of 90g of ethanol and 10g of deionized water, and hydrolysis is performed under stirring at 500rpm for 30min to prepare a coupling agent aqueous solution;

[0072] (2) 60g of fillers (36g of B4C, 5.52g of ZrB2, 7.2g of SiC w , and 11.28g of ZrSi2) are added to the coupling agent aqueous solution, and after stirring at 300rpm for 50min, the mixture is placed in a forced air drying oven and dried at 80℃ for 2h;

[0073] (3) 6g of KOS-110 and 1.6g of dicumyl peroxide are added to 40g of polysilazane, and stirring is performed at 500rpm for 10min to obtain a polysilazane solution;

[0074] (4) The dried fillers of step (2) are added to the polysilazane solution, and stirring is performed at 500rpm for 2h to prepare a high-temperature-resistant ceramic adhesive.

[0075] The application of the high-temperature-resistant ceramic adhesive is applied to the bonding of Si3N4 ceramic blocks.

[0076] The bonding method of the Si3N4 ceramic block comprises the following steps:

[0077] 1) Put the Si3N4 ceramic block into ethanol and ultrasonic for 30min, take it out and dry it in an oven at 60℃ for 2h, then apply the high-temperature-resistant ceramic adhesive to the contact surfaces of the two Si3N4 ceramic blocks (30mm×10mm×5mm) to be bonded in a double-sided adhesive manner under the conditions of a temperature of 30℃ and a humidity of 40%, with a brushing thickness of 200μm and a brushing area of 10mm×10mm, and then place the two surfaces with the high-temperature-resistant ceramic adhesive for 5min, and then adhere the two surfaces together to achieve preliminary bonding; Figure 1 ​

[0078] 2) Put the sample after the initial bonding of step 1) into a vacuum drying oven for heat curing treatment: increase the temperature to 80℃ at a rate of 4℃ / min and keep for 120min; then gradually increase the temperature to 100℃, 120℃, 140℃, 160℃, 180℃ at a rate of 2℃ / min and keep for 120min at each temperature point; after the curing is completed, cool to room temperature at a rate of 5℃ / min;

[0079] 3) Put the sample after the curing of step 2) into an Al2O3 tube furnace for high-temperature sintering treatment under a nitrogen atmosphere: increase the temperature to 200℃ at a rate of 5℃ / min and keep for 60min; then gradually increase the temperature to 400℃, 600℃, 800℃, 1100℃ at a rate of 2℃ / min and keep for 60min at each temperature point, and finally cool to room temperature at a rate of 5℃ / min to complete the bonding of the Si3N4 ceramic block.

[0080] Comparative Example 1

[0081] The difference from Example 1 is that in step (2) of the preparation method of the ceramic binder, the filler is 50g of ZrB2, and the others are the same as Example 1.

[0082] Comparative Example 2

[0083] The difference from Example 2 is that the bonding method of the Si3N4 ceramic block does not include steps 2) and 3), and the heat treatment step is: after the initial bonding of step 1), directly increase the temperature to 200℃ at a rate of 5℃ / min and keep for 60min under a nitrogen atmosphere; then gradually increase the temperature to 400℃, 600℃, 800℃, 1100℃ at a rate of 2℃ / min and keep for 60min at each temperature point, and finally cool to room temperature at a rate of 5℃ / min, i.e. complete the bonding of the Si3N4 ceramic block.

[0084] The others are the same as Example 2.

[0085] Comparative Example 3

[0086] The difference from Example 2 is that in step (2) of the preparation method of the ceramic binder, the filler is 88g of B4C and 12g of SiC w , and the others are the same as Example 2.

[0087] Comparative Example 4

[0088] The difference from Example 1 is that in step (2) of the preparation method of the ceramic binder, the filler is 30g of ZrSi2, 10g of B4C and 10g of SiC w .

[0089] Comparative Example 5

[0090] The difference from Example 1 is that the Si3N4 ceramic block is replaced by a SiBON ceramic block in the application of the high-temperature-resistant ceramic binder.

[0091] Comparative Example 6

[0092] The difference from Example 2 is that the filler in step (2) of the preparation method of the ceramic binder is 68 g of B4C, 12 g of SiC, 6 g of SiO2 and 14 g of ZrO2. w

[0093] Comparative Example 7

[0094] The difference from Example 2 is that the Si3N4 ceramic block is replaced by a SiBON ceramic block in the application of the high-temperature-resistant ceramic binder.

[0095] The ceramic binders prepared in Examples 1-3 and Comparative Examples 1-3, 4, 6 are respectively subjected to performance testing, and the testing method is as follows:

[0096] The ceramic binder sample is placed in a holding furnace, heated to 1100℃ at a rate of 10℃ / min for heat treatment for 60 min, and then cooled to room temperature. After taking out, the density, open porosity, water absorption and bending strength of the sample are respectively tested, wherein:

[0097] The testing method of the density, open porosity and water absorption is: the Archimedes drainage method is used for testing;

[0098] The testing method of the bending strength is: the testing is carried out according to ISO 14704:2016, the sample specification is 35mm×4mm×3mm, the support span is 30mm, the loading rate of the pressure head is 0.5mm / min, and 3-5 samples are tested in parallel for each group.

[0099] The test results are shown in Table 1.

[0100] Table 1 Performance test results of the ceramic binder after heat treatment at 1100℃

[0101]

[0102] As can be seen from Table 1, the ceramic binder prepared in the examples has high bending strength and density; when the type of filler, the content of filler or the bonding heat treatment process is changed in the comparative examples, the ceramic binder prepared has low bending strength and density. This result fully embodies the significant performance advantage of the high-temperature-resistant ceramic binder of the present application.

[0103] ​The shear strength at room temperature and the shear strength at high temperature of the bonded ceramic block in Examples 1-3 and Comparative Examples 1-7 were tested respectively: the test method referred to ASTM D1002-10 (2019). Among them, the shear strength at room temperature was tested by using a room temperature universal testing machine, and the shear strength at high temperature (800℃ and 1100℃) was tested by using a high temperature universal testing machine.

[0104] The test results are shown in Table 2.

[0105] Table 2 Performance test results of bonded ceramic block

[0106]

[0107] In the present application, the bonding joint of the bonded ceramic block gradually undergoes the following reactions during heat treatment: when the heat treatment temperature is 200℃, cross-linking occurs between the active small molecules of the ceramic bonding agent, accompanied by the release of gas small molecules, the cross-linked organic matrix can form bonds with the hydroxyl groups on the Si3N4 ceramic block, at this time the ceramic bonding agent exhibits excellent bonding strength to the Si3N4 ceramic block. When the temperature rises to 400-600℃, the organic matrix decomposes and gradually converts into inorganic ceramic, gas small molecules are released, part of the filler is oxidized, and the cohesion of the ceramic bonding agent itself decreases, resulting in a decrease in the bonding strength of the bonding joint. When the heat treatment temperature rises to 1100℃, chemical and physical reactions occur inside the ceramic bonding agent and between the ceramic bonding agent and the Si3N4 ceramic block substrate, at this time the bonding joint is in a relatively stable state, and the bonding strength of the bonding joint is improved.

[0108] As can be seen from Table 2, the high-temperature-resistant ceramic bonding agent prepared in air atmosphere shows a gradual downward trend with the increase of test temperature. For the high-temperature-resistant ceramic bonding agent (Example 1 and Comparative Example 1) subjected to high-temperature sintering treatment in air atmosphere, at 1100℃, ZrB2 in Comparative Example 1 is oxidized to form ZrO2 and B2O3 oxides, which can compensate for the volume shrinkage caused by the decomposition of polysilazane organic components, thus improving the bonding strength, but the improvement is limited; in Example 1, there are not only oxidation reactions of ZrB2, but also oxidation reactions of B4C and SiC w at high temperature, which together generate ZrO2-SiO2-B2O3 glass phase, in addition, the addition of SiC w can play the role of crack deflection and bridging, therefore, when B4C, ZrB2 and SiC w are added in polysilazane at the same time, the performance of the bonding agent is best.

[0109] The high-temperature-resistant ceramic binder prepared in a nitrogen atmosphere showed a trend of first decreasing and then increasing with the increase of the test temperature. For the high-temperature-resistant ceramic binder sintered in a nitrogen atmosphere (Example 2, Example 3, Comparative Example 2 and Comparative Example 3), at 1100 DEG C, compared with Comparative Example 3, ZrB2 and ZrSi2 were added in Example 2 and Example 3, and under high temperature, ZrSi2 and ZrB2 in the binder can form chemical bonds (C-N / Si-B / B-N) with the amorphous glass phase or other fillers after the polysilazane is ceramized, so as to make the whole bonding system more stable. Compared with Comparative Example 2, the bonding joint of the example gradually increased in temperature during the heat treatment process, so that the organic small molecules in the joint were slowly released, and the bonding strength of the bonding joint was improved.

Claims

1. Use of a high temperature resistant ceramic binder, characterized in that, The application relates to a bonding method for Si3N4 ceramic blocks. The bonding method for the Si3N4 ceramic blocks comprises the following steps: 1) under the conditions of a temperature of 25-30 DEG C and a humidity of 30-40%, high-temperature-resistant ceramic adhesive is uniformly applied on the contact surfaces of two Si3N4 ceramic blocks to be bonded by adopting a double-sided gluing mode, and then the two surfaces coated with the high-temperature-resistant ceramic adhesive are pasted together to realize preliminary bonding; 2) the sample after the preliminary bonding in step 1) is subjected to heat curing treatment: the temperature is increased to 79-81 DEG C at a rate of 4-5 DEG C / min and is kept for 115-125 min; then the temperature is gradually increased to 95-105 DEG C, 115-125 DEG C, 135-145 DEG C, 155-165 DEG C and 175-185 DEG C at a rate of 2-3 DEG C / min, and is kept for 115-125 min at each temperature point, and after the curing is completed, the sample is cooled to room temperature at a rate of 4-5 DEG C / min; 3) the sample after the curing in step 2) is placed into a tube furnace, and high-temperature sintering treatment is carried out under an air or nitrogen atmosphere: the temperature is increased to 195-205 DEG C at a rate of 4-5 DEG C / min and is kept for 55-65 min; then the temperature is gradually increased to 395-405 DEG C, 595-605 DEG C, 795-805 DEG C and 1095-1105 DEG C at a rate of 2-3 DEG C / min, and is kept for 55-65 min at each temperature point, finally the sample is cooled to room temperature at a rate of 4-5 DEG C / min, and the bonding of the Si3N4 ceramic blocks is completed; The preparation method of the high-temperature-resistant ceramic adhesive comprises the following steps: (1) a coupling agent is added into a mixed solution of ethanol and deionized water, and hydrolysis is carried out through stirring to prepare a coupling agent aqueous solution; (2) fillers are added into the coupling agent aqueous solution, and after stirring and activation treatment, the fillers are dried; (3) a dispersing agent and a thermal initiator are added into polysilazane, and stirring is uniformly carried out to obtain a polysilazane solution; (4) the dried fillers in step (2) are added into the polysilazane solution, and stirring is uniformly carried out to prepare the high-temperature-resistant ceramic adhesive; The high-temperature-resistant ceramic adhesive is applied to the bonding of Si3N4 ceramic blocks, and the bonding process needs to pass through two heat treatments of heat curing treatment and high-temperature sintering treatment; When the high-temperature sintering process is carried out in an air atmosphere, the fillers selected are B4C, ZrB2and SiC w When the high-temperature sintering process is carried out in a nitrogen atmosphere, the fillers selected are B4C, ZrB2, ZrSi2and SiC w .

2. Use of a refractory ceramic binder according to claim 1, characterized in that, In step (1), the coupling agent is KH-550, the stirring speed is 300-500 rpm, and the stirring time is 30-50 min; the mass ratio of the ethanol to the deionized water is (9-10):

1.

3. Use of a refractory ceramic binder according to claim 1, characterized in that, In step (2), the adding amount of the coupling agent is 1-2 wt.% of the total amount of the fillers; the stirring speed is 300-500 rpm, and the stirring time is 30-50 min.

4. Use of a refractory ceramic binder according to claim 1, characterized in that, In step (3), the dispersing agent is BYK-2070 or KOS-110, the thermal initiator is dicumyl peroxide, and the structural formula of the polysilazane is as follows: ； In the formula, n is the number of repeating units in the polymer.

5. Use of the refractory ceramic binder according to claim 1, characterized in that, The amount of the thermal initiator is 2-4wt.% of the total amount of polysilazane; the amount of polysilazane is 30-60wt.% of the total amount of coupling agent, filler, dispersant, thermal initiator and polysilazane; the amount of the dispersant is 10-20wt.% of the total amount of the filler.

6. Use of a refractory ceramic binder according to claim 1, characterized in that, In the step (3), the stirring speed is 300-500rpm and the stirring time is 10-30min; in the step (4), the stirring speed is 300-500rpm and the stirring time is 2-3h.

7. Use of the refractory ceramic binder according to claim 1, characterized in that, When the high-temperature resistant ceramic binder is applied in air atmosphere, the raw materials selected include, by mass percentage: 8-32 wt.% of B4C, 30 wt.% of ZrB2, 8-32 wt.% of SiC w and 30-60 wt.% of polysilazane; when applied in nitrogen atmosphere, the raw materials selected include, by mass percentage: 34-36 wt.% of B4C, 2-9.2 wt.% of ZrB2, 7-12 wt.% of ZrSi2, 6-7.2 wt.% of SiC w and 40-50 wt.% of polysilazane.

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