Bn-sibcn composite ceramic for thin strip continuous casting side sealing plate and preparation method thereof

Abstract

The application relates to BN-SiBCN composite ceramic for thin strip continuous casting side sealing plates and a preparation method thereof. The technical scheme is as follows: according to the mass ratio of BN micropowder to SiBCN micropowder 1:(1-5), ingredients are mixed to obtain mixed powder; the mixed powder is placed in a ball mill tank and ball milled under the conditions of Ar atmosphere and the mass ratio of grinding balls to mixed powder (5-50):1 to obtain ball mill material; the ball mill material is dried in a vacuum drying box, the dried BN-SiBCN micropowder is placed in a mold, and pressure is maintained at 10-100 MPa for 1-20 min to prepare a BN-SiBCN blank; the graphite mold with the BN-SiBCN blank is placed in a hot pressing furnace, heated to 1400-2000 DEG C under vacuum, pressure is maintained at 10-100 MPa, and the furnace is cooled to obtain the BN-SiBCN composite ceramic for thin strip continuous casting side sealing plates. The product prepared by the application has high density, excellent wear resistance, good thermal shock resistance, excellent oxidation resistance, good molten steel erosion resistance and long service life.

Description

Technical Field

[0001] This invention belongs to the technical field of side sealing plates for thin strip continuous casting. Specifically, it relates to a BN-SiBCN composite ceramic for side sealing plates in thin strip continuous casting and its preparation method. Background Technology

[0002] Thin strip continuous casting involves directly injecting molten metal through an tundish between two casting rolls to form a thin strip with a thickness of 2–10 mm. This continuous casting method offers advantages such as a short process flow, high efficiency, low energy consumption, and low cost. Side sealing plates in thin strip continuous casting are crucial leak-proof devices designed to create a molten metal pool between the two casting rolls. They constrain the molten metal, promote strip formation, and ensure the quality of the strip edges. Their performance is a key factor affecting the continuity of the thin strip continuous casting process and the overall quality of the cast strip. Commonly used materials for thin strip side sealing plates include magnesia-chromium refractories, fused silica refractories, and zircon refractories. However, these materials have poor wear resistance, corrosion resistance, oxidation resistance, and thermal shock resistance, resulting in a short service life and hindering technological advancements and efficiency improvements in thin strip casting.

[0003] Borestone (BN) ceramics are widely used in thin-strip continuous casting technology for side sealing plates due to their excellent comprehensive mechanical properties (high strength, high hardness, and high toughness), good high-temperature oxidation resistance, good high-temperature chemical stability, and non-wetting properties with molten metal. However, their poor sinterability, high sintering temperature, and difficult densification process limit the improvement of BN ceramic performance. SiBCN ceramics, on the other hand, are easy to sinter and possess excellent high-temperature structural stability, good creep resistance, and thermal shock resistance. Therefore, by uniformly mixing appropriate amounts of BN micropowder and SiBCN micropowder and then hot-pressing and sintering at high temperature, a BN-SiBCN composite ceramic is prepared. This composite ceramic not only achieves sintering densification but also exhibits high-temperature structural stability, high strength, high hardness, high toughness, good wear resistance, good creep resistance, thermal shock resistance, oxidation resistance, and resistance to molten steel corrosion, thus meeting the actual service performance requirements of thin-strip continuous casting side sealing plates.

[0004] The patented technology, "Side Sealing Plate for Thin Strip Continuous Casting and Manufacturing Method" (201010112361.7), uses boron nitride, zirconium boride, zirconium oxide, carbon fiber, boron powder, and graphite as raw materials. The process involves carbon embedding and sintering (1450–1550℃), followed by vacuum pressure oil impregnation to obtain the side sealing plate for thin strip continuous casting. While the presence of graphite and carbon fiber in the raw materials used in this patented technology can improve the material's strength, it reduces its oxidation resistance, leading to a shorter service life.

[0005] The patented technology, "A BN Nanosheet-Toughened High Thermal Conductivity AlN Ceramic Substrate and Preparation Method," (202210562483.9), uses boron nitride powder, aluminum nitride powder, and yttrium oxide powder as raw materials. The composite powder is prepared through three ball milling processes, and then heat-treated at 1750–1850℃ to obtain the BN ceramic substrate. This patented technology involves numerous ball milling cycles, a long processing time, and a prolonged high-temperature sintering time, making the preparation process cumbersome and difficult to control.

[0006] The patented technology, "Side sealing plate for continuous casting of thin steel strip and its preparation method" (201410166781.1), uses boron nitride, zircon, zirconium silicate, silicon carbide, magnesium boride, boron carbide, silicon dioxide, and additives as raw materials. The raw materials are first ball-milled for 12 hours to form a slurry, then mixed and ball-milled again for 5–48 hours. After mixing, the mixture is hot-pressed and sintered at 1500–2000℃, corresponding to a pressure of 20–90 MPa. This patented technology requires processing too many types of raw materials and involves excessively long ball-milling and mixing times, resulting in a lengthy and complex preparation process, making it unsuitable for large-scale industrial production.

[0007] The patented technology, "Max Phase-Boron Nitride Composite Ceramic Side Sealing Plate for Thin Strip Continuous Casting and its Manufacturing Method" (201510245921.9), uses boron nitride, SiC powder, Ti powder, Al powder, and activated carbon powder as raw materials. First, Ti powder, Al powder, and activated carbon powder are mixed and hot-pressed to prepare a Max phase sintered body. Then, the Max phase is mixed with boron nitride powder and sintered by spark plasma to prepare the side sealing plate for thin strip continuous casting. This patented technology has a relatively cumbersome manufacturing process, making it difficult to control. Furthermore, the presence of Ti powder and activated carbon powder in the raw materials results in poor oxidation resistance of the composite ceramic, leading to a short service life and failing to meet the actual service performance requirements of thin strip continuous casting side sealing plates.

[0008] The patented technology, "Boron Nitride-Based Ceramic Side Sealing Plate Material for Thin Strip Continuous Casting and Its Preparation Method" (201510689600.8), uses boron nitride, zirconium oxide, silicon carbide, and borate as raw materials. First, zirconium oxide, silicon carbide, and borate are ball-milled for 10–48 hours to prepare a composite powder. Then, boron nitride is ball-milled with the composite powder for 24 hours. After ball milling, the powder is dried in a drying oven for 24 hours to obtain boron nitride composite powder. The boron nitride composite powder is then pre-fired at 1300℃ for 0.5–5 hours, followed by hot-pressing sintering at 1200–1400℃ for 0.5–5 hours to obtain the boron nitride-based ceramic material for thin strip continuous casting. This patented technology involves complex raw material processing, multiple high-temperature heat treatment steps, and difficult process control, which is not conducive to the large-scale preparation of side sealing plates for thin strip continuous casting.

[0009] The patented technology, "Method for Preparing BN / SiO2 Composite Ceramics by Precursor Impregnation and Pyrolysis" (200410013684.5), uses BN powder and polysilane as raw materials, pre-firing at 800℃ followed by vacuum sintering at 1300℃ to prepare BN / SiO2 composite ceramics. This patented technology uses BN powder and organopolysilane to prepare BN composite ceramics, but the raw materials used are expensive, and the BN composite ceramics prepared by the high-temperature pyrolysis method cannot achieve densification, resulting in porous materials that fail to meet the industrial requirements of simple availability and good overall performance.

[0010] Currently, the preparation of BN composite ceramics and thin strip continuous casting side sealing plates generally suffers from technical defects such as high raw material costs, complex synthesis processes, difficulty in achieving complete densification, and poor oxidation resistance. Summary of the Invention

[0011] The present invention aims to overcome the defects of the prior art and provides a method for preparing BN-SiBCN composite ceramics for thin strip continuous casting side sealing plates that is simple in process, short in cycle, low in cost and suitable for industrial production. The prepared BN-SiBCN composite ceramics for thin strip continuous casting side sealing plates have high density, high strength, high hardness, excellent wear resistance, good thermal shock resistance, excellent oxidation resistance, good resistance to molten steel corrosion and long service life.

[0012] To achieve the above objectives, the technical solution adopted by the present invention includes the following steps:

[0013] Step 1: Mix the BN micro powder and the SiBCN micro powder at a mass ratio of 1:(1-5) to obtain a mixed powder; place the mixed powder in a ball mill jar and ball mill for 1-24 hours under an Ar atmosphere and a mass ratio of grinding balls to mixed powder of (5-50):1 to obtain ball milling material; then place the ball milling material in a vacuum drying oven and dry it at 50-200℃ for 0.5-5 hours to obtain BN-SiBCN micro powder.

[0014] Step 2: Place the BN-SiBCN micro powder in a mold and hold it under pressure at 10-100 MPa for 1-20 minutes to obtain a BN-SiBCN preform.

[0015] Step 3: The BN-SiBCN blank is loaded into a graphite mold. The inner wall of the graphite mold is provided with graphite foil, and the surface of the graphite foil is coated with BN micro powder. The graphite mold containing the BN-SiBCN blank is then placed in a hot press furnace and heated to 1400-2000℃ at a rate of 1-10℃ / min under vacuum. The temperature is then maintained at 10-100MPa for 1-200min and cooled with the furnace to obtain BN-SiBCN composite ceramic for thin strip continuous casting side sealing plates.

[0016] The particle size of the BN micro powder is 0.5–10 μm; the BN micro powder is h-BN; and the purity of the BN micro powder is ≥99%.

[0017] The SiBCN micro powder has a particle size of 0.5–10 μm and a purity of ≥99%.

[0018] The grinding ball is made of one of the following materials: silicon nitride, tungsten carbide, or stainless steel.

[0019] The thickness of the graphite foil is 0.1 to 1 mm.

[0020] By adopting the above technical solution, the present invention has the following advantages compared with the prior art:

[0021] 1. This invention uses h-BN micro powder and SiBCN micro powder as raw materials, mixes the raw materials uniformly by ball milling, and prepares BN-SiBCN composite ceramics for thin-strip continuous casting side sealing plates by hot pressing sintering. The raw materials used in the preparation process of this invention are simple and readily available, do not cause environmental pollution, and have a short preparation cycle, making them suitable for large-scale industrial production.

[0022] 2. In this invention, h-BN is uniformly distributed in a sheet-like form within the matrix of the composite ceramic, enhancing and toughening it. Furthermore, the low number of internal pores indicates high density. Therefore, the composite ceramic prepared by this invention possesses the advantages of both BN and SiBCN ceramics. It not only achieves sintering densification but also exhibits high strength, high hardness, excellent wear resistance, good thermal shock resistance, superior oxidation resistance, long service life, and good resistance to molten steel corrosion, fully meeting the actual service performance requirements of thin-strip continuous casting side sealing plates.

[0023] 3. The BN-SiBCN composite ceramic for thin strip continuous casting side sealing plates prepared by this invention has the following properties: density of 97.5% to 99.8%, flexural strength at room temperature of 340 to 663 MPa, average oxide layer thickness of 13.2 to 13.6 μm after 2 hours of heat treatment at 1400℃ in air, average slag corrosion layer thickness of 4.9 to 9.8 μm after 1 hour of heat treatment at 1600℃ in air with silicon steel slag as the slag composition, and no fracture phenomenon after 10 cycles of thermal shock at 1100℃. The thermal conductivity at room temperature is 16.7 to 21.4 W / (m·K).

[0024] Therefore, the BN-SiBCN composite ceramic for thin strip continuous casting side sealing plates prepared by this invention has the characteristics of simple process, short cycle, low cost and suitability for industrial production. The prepared BN-SiBCN composite ceramic for thin strip continuous casting side sealing plates not only has high density, high strength and high hardness, but also excellent wear resistance, good thermal shock resistance, excellent oxidation resistance, good resistance to molten steel corrosion and long service life, which fully meets the actual service performance of thin strip continuous casting side sealing plates. Attached Figure Description

[0025] Figure 1 XRD pattern of a BN-SiBCN composite ceramic for a thin strip continuous casting side sealing plate prepared according to the present invention;

[0026] Figure 2 for Figure 1 The image shows a SEM image of BN-SiBCN composite ceramic used in thin strip continuous casting side sealing plates. Detailed Implementation

[0027] The present invention will be further described below with reference to specific implementation examples, but this does not mean that the scope of the present invention is limited to this.

[0028] A BN-SiBCN composite ceramic for thin-strip continuous casting side sealing plates and its preparation method. The steps of the preparation method described in this specific embodiment are as follows:

[0029] Step 1: Mix the BN micro powder and the SiBCN micro powder at a mass ratio of 1:(1-5) to obtain a mixed powder; place the mixed powder in a ball mill jar and ball mill for 1-24 hours under an Ar atmosphere and a mass ratio of grinding balls to mixed powder of (5-50):1 to obtain ball milling material; then place the ball milling material in a vacuum drying oven and dry it at 50-200℃ for 0.5-5 hours to obtain BN-SiBCN micro powder.

[0030] Step 2: Place the BN-SiBCN micro powder in a mold and hold it under pressure at 10-100 MPa for 1-20 minutes to obtain a BN-SiBCN preform.

[0031] Step 3: The BN-SiBCN blank is loaded into a graphite mold. The inner wall of the graphite mold is provided with graphite foil, and the surface of the graphite foil is coated with BN micro powder. The graphite mold containing the BN-SiBCN blank is then placed in a hot press furnace and heated to 1400-2000℃ at a rate of 1-10℃ / min under vacuum. The temperature is then maintained at 10-100MPa for 1-200min and cooled with the furnace to obtain BN-SiBCN composite ceramic for thin strip continuous casting side sealing plates.

[0032] The grinding ball is made of one of the following materials: silicon nitride, tungsten carbide, or stainless steel.

[0033] The thickness of the graphite foil is 0.1 to 1 mm.

[0034] In this specific implementation:

[0035] The particle size of the BN micro powder is 0.5–10 μm; the BN micro powder is h-BN; and the purity of the BN micro powder is ≥99%.

[0036] The SiBCN micro powder has a particle size of 0.5–10 μm and a purity of ≥99%.

[0037] The details will not be repeated in the examples.

[0038] Example 1

[0039] A BN-SiBCN composite ceramic for thin-strip continuous casting side sealing plates and its preparation method. The steps of the preparation method described in this embodiment are as follows:

[0040] Step 1: Mix the BN micro powder and the SiBCN micro powder at a mass ratio of 1:1 to obtain a mixed powder. Place the mixed powder in a ball mill jar and ball mill for 1 hour under an Ar atmosphere and a mass ratio of grinding balls to mixed powder of 5:1 to obtain ball milling material. Then place the ball milling material in a vacuum drying oven and dry it at 50°C for 0.5 hours to obtain BN-SiBCN micro powder.

[0041] Step 2: Place the BN-SiBCN micro powder in a mold and hold it under pressure at 10MPa for 1 minute to obtain a BN-SiBCN preform.

[0042] Step 3: The BN-SiBCN blank is loaded into a graphite mold. The inner wall of the graphite mold is provided with graphite foil, and the surface of the graphite foil is coated with BN micro powder. The graphite mold containing the BN-SiBCN blank is then placed in a hot press furnace and heated to 1400℃ at a rate of 1℃ / min under vacuum. The temperature is then held at 10MPa for 200min and cooled with the furnace to obtain BN-SiBCN composite ceramic for thin strip continuous casting side sealing plates.

[0043] The grinding balls are made of silicon nitride.

[0044] The graphite foil has a thickness of 0.1 mm.

[0045] Example 2

[0046] A BN-SiBCN composite ceramic for thin-strip continuous casting side sealing plates and its preparation method. The steps of the preparation method described in this embodiment are as follows:

[0047] Step 1: Mix the BN micro powder and the SiBCN micro powder at a mass ratio of 1:1.5 to obtain a mixed powder. Place the mixed powder in a ball mill jar and ball mill for 4 hours under an Ar atmosphere and a mass ratio of grinding balls to mixed powder of 10:1 to obtain a ball milling material. Then place the ball milling material in a vacuum drying oven and dry it at 60°C for 1.5 hours to obtain BN-SiBCN micro powder.

[0048] Step 2: Place the BN-SiBCN micro powder in a mold and hold it under pressure at 20MPa for 4 minutes to obtain a BN-SiBCN preform.

[0049] Step 3: The BN-SiBCN blank is loaded into a graphite mold. The inner wall of the graphite mold is provided with graphite foil, and the surface of the graphite foil is coated with BN micro powder. The graphite mold containing the BN-SiBCN blank is then placed in a hot press furnace and heated to 1500℃ at a rate of 2℃ / min under vacuum. The temperature is then held at 20MPa for 170min and cooled with the furnace to obtain BN-SiBCN composite ceramic for thin strip continuous casting side sealing plates.

[0050] The grinding ball is made of tungsten carbide.

[0051] The graphite foil has a thickness of 0.2 mm.

[0052] Example 3

[0053] A BN-SiBCN composite ceramic for thin-strip continuous casting side sealing plates and its preparation method. The steps of the preparation method described in this embodiment are as follows:

[0054] Step 1: Mix the BN micro powder and the SiBCN micro powder at a mass ratio of 1:2 to obtain a mixed powder. Place the mixed powder in a ball mill jar and ball mill for 8 hours under an Ar atmosphere and a mass ratio of grinding balls to mixed powder of 15:1 to obtain a ball milling material. Then place the ball milling material in a vacuum drying oven and dry it at 80°C for 2 hours to obtain BN-SiBCN micro powder.

[0055] Step 2: Place the BN-SiBCN micro powder in a mold and hold it under pressure at 350MPa for 8 minutes to obtain a BN-SiBCN preform.

[0056] Step 3: The BN-SiBCN blank is loaded into a graphite mold. The inner wall of the graphite mold is provided with graphite foil, and the surface of the graphite foil is coated with BN micro powder. The graphite mold containing the BN-SiBCN blank is then placed in a hot press furnace and heated to 1600℃ at a rate of 4℃ / min under vacuum. It is then held at 40MPa for 150min and cooled with the furnace to obtain BN-SiBCN composite ceramic for thin strip continuous casting side sealing plates.

[0057] The grinding ball is made of stainless steel.

[0058] The graphite foil has a thickness of 0.4 mm.

[0059] Example 4

[0060] A BN-SiBCN composite ceramic for thin-strip continuous casting side sealing plates and its preparation method. The steps of the preparation method described in this embodiment are as follows:

[0061] Step 1: Mix the BN micro powder and the SiBCN micro powder at a mass ratio of 1:2.5 to obtain a mixed powder. Place the mixed powder in a ball mill jar and ball mill for 12 hours under an Ar atmosphere and a mass ratio of grinding balls to mixed powder of 25:1 to obtain a ball milling material. Then place the ball milling material in a vacuum drying oven and dry it at 110°C for 2.5 hours to obtain BN-SiBCN micro powder.

[0062] Step 2: Place the BN-SiBCN micro powder in a mold and hold it under pressure at 50 MPa for 12 minutes to obtain a BN-SiBCN preform.

[0063] Step 3: The BN-SiBCN blank is loaded into a graphite mold. The inner wall of the graphite mold is provided with graphite foil, and the surface of the graphite foil is coated with BN micro powder. The graphite mold containing the BN-SiBCN blank is then placed in a hot press furnace and heated to 1700℃ at a rate of 5℃ / min under vacuum. The temperature is then held at 50MPa for 120min and cooled with the furnace to obtain BN-SiBCN composite ceramic for thin strip continuous casting side sealing plates.

[0064] The grinding ball is made of tungsten carbide.

[0065] The graphite foil has a thickness of 0.5 mm.

[0066] Example 5

[0067] A BN-SiBCN composite ceramic for thin-strip continuous casting side sealing plates and its preparation method. The steps of the preparation method described in this embodiment are as follows:

[0068] Step 1: Mix the BN micro powder and the SiBCN micro powder at a mass ratio of 1:3.5 to obtain a mixed powder. Place the mixed powder in a ball mill jar and ball mill for 16 hours under an Ar atmosphere and a mass ratio of grinding balls to mixed powder of 35:1 to obtain ball milling material. Then place the ball milling material in a vacuum drying oven and dry it at 140°C for 3 hours to obtain BN-SiBCN micro powder.

[0069] Step 2: Place the BN-SiBCN micro powder in a mold and hold it under pressure at 65 MPa for 15 min to obtain a BN-SiBCN preform.

[0070] Step 3: The BN-SiBCN blank is loaded into a graphite mold. The inner wall of the graphite mold is provided with graphite foil, and the surface of the graphite foil is coated with BN micro powder. The graphite mold containing the BN-SiBCN blank is then placed in a hot press furnace and heated to 1800℃ at a rate of 6℃ / min under vacuum. The temperature is then held at 60MPa for 80min and cooled with the furnace to obtain BN-SiBCN composite ceramic for thin strip continuous casting side sealing plates.

[0071] The grinding balls are made of silicon nitride.

[0072] The graphite foil has a thickness of 0.6 mm.

[0073] Example 6

[0074] A BN-SiBCN composite ceramic for thin-strip continuous casting side sealing plates and its preparation method. The steps of the preparation method described in this embodiment are as follows:

[0075] Step 1: Mix the BN micro powder and the SiBCN micro powder at a mass ratio of 1:4.5 to obtain a mixed powder. Place the mixed powder in a ball mill jar and ball mill for 20 hours under an Ar atmosphere and a mass ratio of grinding balls to mixed powder of 45:1 to obtain a ball milling material. Then place the ball milling material in a vacuum drying oven and dry it at 170°C for 4 hours to obtain BN-SiBCN micro powder.

[0076] Step 2: Place the BN-SiBCN micro powder in a mold and hold it under pressure at 80MPa for 17 minutes to obtain a BN-SiBCN preform.

[0077] Step 3: The BN-SiBCN blank is loaded into a graphite mold. The inner wall of the graphite mold is provided with graphite foil, and the surface of the graphite foil is coated with BN micro powder. The graphite mold containing the BN-SiBCN blank is then placed in a hot press furnace and heated to 1900℃ at a rate of 8℃ / min under vacuum. The temperature is then held at 80MPa for 50min and cooled with the furnace to obtain BN-SiBCN composite ceramic for thin strip continuous casting side sealing plates.

[0078] The grinding ball is made of stainless steel.

[0079] The thickness of the graphite foil is 0.8 mm.

[0080] Example 7

[0081] A BN-SiBCN composite ceramic for thin-strip continuous casting side sealing plates and its preparation method. The steps of the preparation method described in this embodiment are as follows:

[0082] Step 1: Mix the BN micro powder and the SiBCN micro powder at a mass ratio of 1:5 to obtain a mixed powder. Place the mixed powder in a ball mill jar and ball mill for 24 hours under an Ar atmosphere and a mass ratio of grinding balls to mixed powder of 50:1 to obtain a ball milling material. Then place the ball milling material in a vacuum drying oven and dry it at 200°C for 5 hours to obtain BN-SiBCN micro powder.

[0083] Step 2: Place the BN-SiBCN micro powder in a mold and hold it under pressure at 100MPa for 20 minutes to obtain a BN-SiBCN preform.

[0084] Step 3: The BN-SiBCN blank is loaded into a graphite mold. The inner wall of the graphite mold is provided with graphite foil, and the surface of the graphite foil is coated with BN micro powder. The graphite mold containing the BN-SiBCN blank is then placed in a hot press furnace and heated to 2000℃ at a rate of 10℃ / min under vacuum. The temperature is then held at 100MPa for 1min and cooled with the furnace to obtain BN-SiBCN composite ceramic for thin strip continuous casting side sealing plates.

[0085] The grinding ball is made of tungsten carbide.

[0086] The graphite foil has a thickness of 1 mm.

[0087] This specific implementation method has the following advantages compared with the prior art:

[0088] 1. This specific embodiment uses h-BN micro powder and SiBCN micro powder as raw materials. The raw materials are mixed evenly by ball milling, and BN-SiBCN composite ceramics for thin strip continuous casting side sealing plates are prepared by hot pressing sintering. The raw materials used in this specific embodiment are simple and readily available, do not cause environmental pollution, and have a short preparation cycle, making them suitable for large-scale industrial production.

[0089] 2. The BN-SiBCN composite ceramic for the thin strip continuous casting side sealing plate prepared in this specific embodiment is shown in the attached figure. Figure 1 The XRD pattern of the BN-SiBCN composite ceramic for the thin strip continuous casting side sealing plate prepared in Example 4; Figure 2 for Figure 1 The image shown is a SEM image of BN-SiBCN composite ceramic used in thin-strip continuous casting side sealing plates. From... Figure 1 It can be seen that the main component of the BN-SiBCN composite ceramic used in thin strip continuous casting side sealing plates is h-BN, followed by SiCN and B4C. This indicates that after hot pressing and sintering, it retains the advantages of both BN and SiBCN ceramics, exhibiting high strength, high hardness, excellent wear resistance, good thermal shock resistance, excellent oxidation resistance, long service life, and good resistance to molten steel erosion. This fully meets the actual service performance requirements of thin strip continuous casting side sealing plates. Figure 2 It can be seen that h-BN is uniformly distributed in the matrix of the composite ceramic in the form of flakes, which enhances and toughens the composite ceramic. Moreover, the number of pores inside the ceramic is small, indicating that the composite ceramic has high density.

[0090] 3. The BN-SiBCN composite ceramic for thin strip continuous casting side sealing plates prepared in this specific embodiment has the following properties: density of 97.5% to 99.8%, flexural strength at room temperature of 340 to 663 MPa, average oxide layer thickness of 13.2 to 13.6 μm after being kept at 1400℃ in air for 2 hours, average slag corrosion layer thickness of 4.9 to 9.8 μm after being kept at 1600℃ in air for 1 hour under the condition that the slag composition is silicon steel slag, and no fracture phenomenon after 10 cycles of thermal shock at 1100℃, and thermal conductivity at room temperature of 16.7 to 21.4 W / (m·K).

[0091] Therefore, the BN-SiBCN composite ceramic for thin strip continuous casting side sealing plates prepared in this specific embodiment has the characteristics of simple process, short cycle, low cost and suitability for industrial production. The prepared BN-SiBCN composite ceramic for thin strip continuous casting side sealing plates not only has high density, high strength and high hardness, but also excellent wear resistance, good thermal shock resistance, excellent oxidation resistance, good resistance to molten steel corrosion and long service life, which fully meets the actual service performance of thin strip continuous casting side sealing plates.

Claims

1. A method for preparing BN-SiBCN composite ceramic for thin strip continuous casting side seal plate, characterized by The preparation method comprises the following steps: Step 1, mixing BN micropowder and SiBCN micropowder according to a mass ratio of 1: (1-5) to obtain mixed powder; putting the mixed powder into a ball mill tank under the conditions of Ar atmosphere and a mass ratio of grinding ball to mixed powder of (5-50):1, and ball milling for 1-24 hours to obtain ball milling material; and then drying the ball milling material in a vacuum drying box under the condition of 50-200 DEG C for 0.5-5 hours to obtain BN-SiBCN micropowder; Step 2, putting the BN-SiBCN micropowder into a mold under the condition of 10-100 MPa for 1-20 minutes to obtain BN-SiBCN green body; Step 3, putting the BN-SiBCN green body into a graphite mold, wherein the inner wall of the graphite mold is provided with graphite foil, and the surface of the graphite foil is coated with BN micropowder; and then putting the graphite mold with the BN-SiBCN green body into a hot pressing furnace, heating to 1400-2000 DEG C at a rate of 1-10 DEG C / min under vacuum environment, and then keeping temperature and pressure under the condition of 10-100 MPa for 1-200 minutes, and cooling in the furnace to obtain BN-SiBCN composite ceramic for thin strip continuous casting side sealing plate.

2. The method of claim 1, wherein the BN-SiBCN composite ceramic for a thin strip continuous casting side seal plate is prepared by the steps of: preparing a BN-SiBCN composite ceramic slurry by mixing a BN-SiBCN composite ceramic powder, a binder, and a solvent; coating the BN-SiBCN composite ceramic slurry on a substrate; and drying the coated substrate. The particle size of the BN micropowder is 0.5-10 microns, the BN micropowder is h-BN, and the purity of the BN micropowder is greater than or equal to 99%.

3. The method of claim 1, wherein the BN-SiBCN composite ceramic for a thin strip continuous casting side seal plate is prepared by the steps of: preparing a BN-SiBCN composite ceramic slurry by mixing a BN-SiBCN composite ceramic powder, a binder, and a solvent; coating the BN-SiBCN composite ceramic slurry on a substrate; and drying the coated substrate. The particle size of the SiBCN micropowder is 0.5-10 microns, and the purity of the SiBCN micropowder is greater than or equal to 99%.

4. The method of claim 1, wherein the BN-SiBCN composite ceramic for a thin strip continuous casting side seal plate is prepared by the steps of: preparing a BN-SiBCN composite ceramic slurry by mixing a BN-SiBCN composite ceramic powder, a binder, and a solvent; coating the BN-SiBCN composite ceramic slurry on a substrate; and drying the coated substrate. The material of the grinding ball is one of silicon nitride, tungsten carbide and stainless steel.

5. The method of claim 1, wherein the BN-SiBCN composite ceramic for a thin strip continuous casting side seal plate is prepared by the steps of: preparing a BN-SiBCN composite ceramic slurry by mixing a BN-SiBCN composite ceramic powder, a binder, and a solvent; coating the BN-SiBCN composite ceramic slurry on a substrate; and drying the coated substrate. The thickness of the graphite foil is 0.1-1 mm.

6. A BN-SiBCN composite ceramic for a thin strip continuous casting side seal plate, characterized by The BN-SiBCN composite ceramic for thin strip continuous casting side sealing plate is prepared according to the preparation method of the BN-SiBCN composite ceramic for thin strip continuous casting side sealing plate in any one of claims 1-5.

Images