A novel high thermal conductivity TiN / Ti(C) x N 1-x Sialon-SiC composite refractory material

Abstract

This invention belongs to the field of refractory materials. It proposes a novel high thermal conductivity TiN / Ti(C) material. x N 1‑x Sialon-SiC composite refractory, wherein the main crystalline phase of the composite refractory is SiC, and the bonding phase contains at least Siialon and TiN or Ti(C) x N 1‑x The composition contains two or three phases, with the main crystalline phase accounting for 70-90% by weight and the bonding phase accounting for 10-30%. This invention utilizes the reduction and nitriding properties of silicon powder at high temperatures to simultaneously deoxidize the titanium oxide in the titanium source material and induce a nitriding reaction. Furthermore, under the action of trace oxide sintering aids contained in the titanium source material, it dissolves with Al2O3 to generate Sialon, TiN, or Ti(C) compounds. x N 1‑x The TiN / Ti(C) group is a nitride-based phase. x N 1‑x Sialon-SiC is a novel material system that combines SiC, TiN, and Ti(C) alloys. x N 1‑x Sialon exhibits high thermal conductivity and chemical stability, with a thermal conductivity ≥22 W·m at 1000℃. ‑1 ·k ‑1 The design of the multiphase material gives the material system excellent thermal shock resistance, making it suitable for various high-temperature and corrosive working conditions, especially for the lining of high-temperature kilns with water cooling.

Description

Technical Field

[0001] This invention belongs to the field of refractory materials, and particularly relates to a novel high thermal conductivity TiN / Ti(C) material. x N 1-x Sialon-SiC composite refractory material. Background Technology

[0002] Silicon carbide, due to its high melting point and decomposition temperature (2700℃), high hardness, high thermal conductivity, and excellent chemical stability, is widely used as a refractory material in various high-temperature environments with severe chemical corrosion. Silicon carbide is not a natural raw material but is artificially synthesized by mixing quartz sand with petroleum coke or anthracite at temperatures of 2000-2500℃. Because silicon carbide's sintering temperature is typically above 2000℃ and its cost is high, it is mostly used as an aggregate in the refractory materials field, with designs incorporating a binder phase that can be sintered at relatively low temperatures to prepare silicon carbide refractory products. In high-temperature metallurgical applications… The silicon carbide refractory products widely used in this field are mainly oxide-bonded SiC and nitride-bonded SiC. Oxide-bonded SiC refractory products mainly include clay-bonded SiC, mullite-bonded SiC, and SiO2-bonded SiC, while nitride-bonded SiC products mainly include Si3N4-SiC, SiN2O2-SiC, Si3N4 / SiN2O2-SiC, and Sialon-SiC. Nitride-bonded SiC refractory materials have a small coefficient of linear expansion, high strength at both room and high temperatures, and good thermal conductivity (≥16 W·m at 1000℃). -1 ·k -1 It has excellent properties such as good thermal shock resistance, good resistance to slag and molten metal penetration and corrosion, and is widely used in the fields of steel, non-ferrous metallurgy, chemical, electric power, ceramics and environmental protection.

[0003] The longevity of high-temperature metallurgical furnace linings largely depends on heat conduction and reducing the temperature of the working surface. For example, the design of water-cooled walls and jackets in different parts of blast furnaces is primarily aimed at heat conduction and reducing the temperature of the working surface of the lining. Lowering the working surface temperature increases the lining's resistance to corrosive gases and slag erosion. Therefore, the thermal conductivity and chemical stability of refractory materials are crucial indicators of their suitability for high-temperature metallurgical furnace conditions. Silicon carbide materials themselves have relatively high thermal conductivity (48 W·m at 1000℃). -1 ·k -1 (Approximately), due to the introduction of non-silicon carbide bonding phases and the non-dense nature of refractory materials, the thermal conductivity of silicon carbide refractories decreases. Oxide-bonded SiC refractories typically have a thermal conductivity below 16 W·m at 1000℃. -1 ·k -1Nitride-bonded SiC refractory products have a thermal conductivity of 16~20 W·m at 1000℃. -1 ·k -1 Scope; Regarding high-temperature chemical stability, the chemical stability of oxide and nitride-bonded phases is lower than that of silicon carbide materials themselves. Among existing silicon carbide products, nitride-bonded silicon carbide materials have relatively high overall chemical stability. Studies have shown that Si3N4 gradually decomposes into the corresponding elemental substances at high temperatures (above 1500℃). Sialon is a solid solution of Si, Al, O, and N. Its pressureless sintering temperature is usually above 1600℃. Lowering the sintering temperature requires the use of expensive metallic Al powder, AlN powder raw materials, and rare earth metal oxide sintering aids. It does not have a specific melting point and decomposes at high temperatures. Its thermal stability is closely related to its crystal form and working atmosphere. Si3N4-SiC and Sialon-SiC products are widely used in blast furnace bodies, bellies, and tuyeres. Studies have shown that under blast furnace conditions, Sialon-SiC has better resistance to alkali corrosion and high-temperature chemical stability. In the nitride system, titanium nitride (TiN) or titanium carbonitride (Ti(C) x N 1-x Both have extremely high melting points (TiN melting point 2950℃, Ti(C) ... x N 1-x (Melt point 2950~3140℃), high hardness, high thermal conductivity, wear resistance, and is not easily wetted or corroded by molten metals or slag. It has excellent high-temperature chemical stability and is a non-oxide material with high corrosion resistance and high thermal shock resistance. Practical research shows that titanium nitride or titanium carbonitride can be deposited on the blast furnace wall and hearth to form a layer of TiN, Ti(C) x N 1-x The slag skin, mainly composed of iron and slag, can effectively prevent the molten iron and slag from corroding the furnace lining material, thus playing a good role in protecting the furnace and extending the blast furnace's lifespan. Summary of the Invention

[0004] Based on TiN, Ti(C) x N 1-x Based on the excellent properties of TiN / Ti(C) and its superior furnace protection performance in the blast furnace ironmaking process, a novel high thermal conductivity TiN / Ti(C) alloy was designed. x N 1-x Sialon-SiC composite refractory materials, using TiN or Ti(C) x N 1-x The introduction of ) enhances the bonding phase of silicon carbide-based refractory materials, improves the thermal conductivity and high-temperature chemical stability of the materials, thereby improving the comprehensive application performance of the materials and increasing the service life of silicon carbide-based refractory products under high-temperature corrosion conditions (such as blast furnaces for ironmaking).

[0005] The technical solution adopted by the present invention to achieve the above objectives is as follows.

[0006] A novel high thermal conductivity TiN / Ti(C) x N 1-x Sialon-SiC composite refractory, wherein the main crystalline phase of the composite refractory is SiC, and the bonding phase contains at least Siialon and TiN or Ti(C) x N 1-x It contains two or three phases, with the main crystalline phase accounting for 70-90% and the bonding phase accounting for 10-30% by weight percentage.

[0007] The raw material composition of the refractory material, by weight percentage, is: 70-90% silicon carbide, 5-15% silicon powder, 0-3% α-Al2O3 micro powder, 3-15% titanium source raw material, plus 2-6% binder and 2-5% water in total of the above raw materials.

[0008] The silicon carbide mentioned includes black silicon carbide and green silicon carbide. The silicon powder refers to metallic silicon powder with a purity of over 98%. The α-Al2O3 micro powder refers to calcined alumina micro powder with a purity of over 99.2%. The titanium source raw materials include titanium concentrate, titanium corundum, high-titanium slag, and other powders with high titanium content.

[0009] The silicon carbide has four particle sizes: 2.5-1.43 mm, 1.43-0.5 mm, 0.5-0 mm, and ≤0.074 mm. The silicon powder has a particle size of ≤0.074 mm, the α-Al2O3 micro powder has a particle size D50 of ≤10 μm, and the titanium source raw material has a particle size of ≤0.074 mm.

[0010] The proportions of different particle sizes are as follows: 2.5 ≤ particle size < 1.43 mm 10-20%, 1.43 ≤ particle size < 0.5 mm 30-50%, 0.5 ≤ particle size < 0 mm 15-30%, and particle size ≤ 0.074 mm 15-30%.

[0011] The above TiN / Ti(C) x N 1-x The preparation method of Sialon-SiC composite refractory material includes the following steps: (1) Weigh all the raw materials according to the proportion, mix them evenly, and knead them to obtain mud; (2) Press the prepared clay into shape and dry it; (3) The dried blank is fired at high temperature to obtain the required refractory material.

[0012] Furthermore, the drying temperature is 120-200℃, and the holding time is 12-48h.

[0013] Furthermore, the firing temperature is 1300-1600℃, the heating rate is 1-15℃ / min, the holding time is 8-36h, and the firing atmosphere is a nitrogen atmosphere.

[0014] Furthermore, the firing methods include electrically heated shuttle kilns, roller kilns, pusher kilns, and gas-fired insulated shuttle kilns.

[0015] This invention proposes a novel high thermal conductivity TiN / Ti(C) x N 1-x The Sialon-SiC composite refractory material, using the above technical solution, has the following beneficial effects: (1) Introducing TiN and Ti(C) into the nitride-bonded SiC system x N 1-x Compared to existing nitride-bonded phases Si3N4, SiN2O2, or Sialon, TiN and Ti(C) x N 1-x It has higher melting point, hardness, thermal conductivity and wear resistance, and is not easily wetted and corroded by molten metal, slag, etc. It has better high-temperature chemical stability, which is conducive to improving the overall performance of the material, especially the thermal conductivity and high-temperature chemical stability of the material.

[0016] (2) This technical solution enables the successful preparation of high-performance, high-value-added TiN / Ti(C) using widely available and low-cost raw materials at medium and low temperatures. x N 1-x Sialon-SiC is a new type of refractory material.

[0017] (3) This invention utilizes the reduction and nitriding properties of silicon powder at high temperatures to deoxidize the titanium oxides in the titanium source material while simultaneously carrying out a nitriding reaction. Furthermore, under the action of trace oxide sintering aids contained in the titanium source material, it dissolves with Al2O3 to generate Sialon, TiN, or Ti(C) x N 1-x The TiN / Ti(C) group is a nitride-based phase. x N 1-x Sialon-SiC is a novel material system that combines SiC, TiN, and Ti(C) compounds. x N 1-x Sialon exhibits high thermal conductivity and chemical stability, with a thermal conductivity ≥22 W·m at 1000℃. -1 ·k -1 The design of the multiphase material gives the material system excellent thermal shock resistance, making it suitable for various high-temperature and corrosive working conditions, especially for the lining of high-temperature kilns with water cooling. Detailed Implementation

[0018] The present invention will be described in detail with reference to specific embodiments: Example 1:

[0019] By weight percentage, the raw material composition is: 70wt% silicon carbide, 15wt% silicon powder, 2wt% α-Al₂O₃ micro powder, 13wt% titanium concentrate powder, plus 2% dextrin, 1% calcium lignosulfonate and 3.5% water. During production, the various raw materials are weighed according to the formula, mixed evenly, and kneaded to obtain a mud. Then, it is pressed into shape using a pressure vibration molding machine and dried at 180℃ for 24 hours. The added silicon carbide is black silicon carbide with particle sizes of 2.5-1.43mm, 1.43-0.5mm, and 0.5-0mm. The added silicon powder is metallic silicon powder with a purity of over 98% and a particle size of 240 mesh; the added α-Al₂O₃ micro powder has a purity of 99.2% and a particle size D50 of 10 μm; the added titanium concentrate powder has a TiO₂ content of 50% and a particle size of 200 mesh; the calcination process is carried out in an electrically heated shuttle kiln at 1400℃ under a nitrogen atmosphere for 12 hours. The resulting phases consist of SiC, TiN, and Ti(C) 0.3 N 0.7 The product is composed of phases such as Silan and a small amount of Si3N4; the physical properties of the obtained product are: apparent porosity 16.3%, bulk density 2.68 g / cm³. 3 It has a room temperature pressure resistance of 196 MPa and a thermal conductivity of 23.8 W·m at 1000℃. -1 ·k -1 . Example 2:

[0020] By weight percentage, the raw material composition is: 75wt% silicon carbide, 13.5wt% silicon powder, 1.5wt% α-Al₂O₃ micro powder, 10wt% high-titanium slag powder, plus 2wt% dextrin, 1wt% calcium lignosulfonate, and 3wt% water. During production, the various raw materials are weighed according to the formula, mixed evenly, and kneaded to obtain a mud. This mud is then pressed into shape using a pressure vibration molding machine and dried at 180℃ for 24 hours. The added silicon carbide is black silicon carbide with particle sizes of 2.5-1.43mm, 1.43-0.5mm, and 0.5-0mm. The added silicon powder is metallic silicon powder with a purity of over 98% and a particle size of 240 mesh; the added α-Al₂O₃ micro powder has a purity of 99.2% and a particle size D50 of 10 μm; the added high-titanium slag powder has a TiO₂ content of 90% and a particle size of 200 mesh; the calcination process is carried out in an electrically heated shuttle kiln at 1420℃ under a nitrogen atmosphere for 12 hours. The resulting phases consist of SiC, TiN, and Ti(C) 0.3 N 0.7 The product is composed of phases such as Silan and a small amount of Si3N4; the physical properties of the obtained product are: apparent porosity 16.5%, bulk density 2.70 g / cm³. 3 It has a compressive strength of 207 MPa at room temperature and a thermal conductivity of 24.3 W·m at 1000℃. -1 ·k -1 . Example 3:

[0021] By weight percentage, the raw material composition is: 75wt% silicon carbide, 15wt% silicon powder, 10wt% titanium corundum powder, plus 2% dextrin, 1% calcium lignosulfonate and 3% water. During production, the various raw materials are weighed according to the formula, mixed evenly, and kneaded to obtain a mud. This mud is then pressed into shape using a pressure vibration molding machine and dried at 180℃ for 24 hours. The added silicon carbide is black silicon carbide with particle sizes of 2.5-1.43mm, 1.43-0.5mm, 0.5-0mm, and 200 mesh. The added silicon powder is metallic silicon powder with a purity of over 98% and a particle size of 240 mesh. The added titanium corundum powder has a TiO2 content of 40% and a particle size of 200 mesh. The material is calcined in an electrically heated shuttle kiln at 1400℃ under a nitrogen atmosphere for 12 hours. The calcined phase consists of SiC and Ti(C)... 0.3 N 0.7 The product is composed of Silan and small amounts of Si3N4, Al2O3, etc.; the physical properties of the obtained product are: apparent porosity 16.0%, bulk density 2.70 g / cm³. 3 It has a compressive strength of 215 MPa at room temperature and a thermal conductivity of 26.9 W·m at 1000℃. -1 ·k -1 . Example 4:

[0022] By weight percentage, the raw material composition is: 75wt% silicon carbide, 15wt% silicon powder, 10wt% titanium corundum powder, plus 2% dextrin, 1% calcium lignosulfonate and 3% water. During production, the various raw materials are weighed according to the formula, mixed evenly, and kneaded to obtain a mud. This mud is then pressed into shape using a pressure vibration molding machine and dried at 180℃ for 24 hours. The added silicon carbide is black silicon carbide with particle sizes of 2.5-1.43mm, 1.43-0.5mm, 0.5-0mm, and 200 mesh. The added silicon powder is metallic silicon powder with a purity of over 98% and a particle size of 240 mesh. The added titanium corundum powder has a TiO2 content of 20% and a particle size of 200 mesh. The material is calcined in an electrically heated shuttle kiln at 1450℃ under a nitrogen atmosphere for 12 hours. The calcined phases consist of SiC, TiN, and Ti(C) 0.3 N 0.7 The product is composed of Silan, Si3N4, Al2O3, and other phases. The physical properties of the obtained product are: apparent porosity 16.4%, bulk density 2.69 g / cm³. 3 It has a compressive strength of 210 MPa at room temperature and a thermal conductivity of 26.1 W·m at 1000℃. -1 ·k -1 . Example 5:

[0023] The raw material composition by weight percentage is: 80wt% silicon carbide, 10wt% silicon powder, 10wt% titanium corundum powder, plus 2% dextrin, 1% calcium lignosulfonate and 2.5% water. During production, the various raw materials are weighed according to the formula, mixed evenly, and kneaded to obtain mud. Then, it is pressed and shaped by a pressure vibration molding machine and dried at 180℃ for 24 hours. The added silicon carbide is black silicon carbide with particle sizes of 2.5-1.43mm, 1.43-0.5mm, 0.5-0mm and 200 mesh. The added silicon powder is metallic silicon powder with a purity of over 98% and a particle size of 240 mesh. The added titanium corundum powder has a TiO2 content of 20% and a particle size of 200 mesh. The firing process is carried out in an electrically heated nitriding roller kiln at 1500℃ under a nitrogen atmosphere for 8 hours. The fired phase consists of SiC, TiN, Sialon and a small amount of Si3N4, Al2O3 and other phases. The physical properties of the obtained product are: apparent porosity 16.9%, bulk density 2.68 g / cm³. 3 It has a compressive strength of 200 MPa at room temperature and a thermal conductivity of 27.5 W·m at 1000℃. -1 ·k -1 .

[0024] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A novel high thermal conductivity TiN / Ti(C) x N 1-x Sialon-SiC composite refractory material, characterized in that: The main crystalline phase of the composite refractory material is SiC, and the bonding phase contains at least Sialon and TiN or Ti(C) x N 1-x It contains two or three phases, with the main crystalline phase accounting for 70-90% and the bonding phase accounting for 10-30% by weight percentage.

2. A novel high thermal conductivity TiN / Ti(C) as described in claim 1 x N 1-x Sialon-SiC composite refractory material, characterized in that: The raw material composition of the refractory material, by weight percentage, is: 70-90% silicon carbide, 5-15% silicon powder, 0-3% α-Al2O3 micro powder, 3-15% titanium source raw material, plus 2-6% binder and 2-5% water in total of the above raw materials.

3. A novel high thermal conductivity TiN / Ti(C) as described in claim 2 x N 1-x Sialon-SiC composite refractory material, characterized in that: The silicon carbide mentioned includes black silicon carbide and green silicon carbide. The silicon powder refers to metallic silicon powder with a purity of over 98%. The α-Al2O3 micro powder refers to calcined alumina micro powder with a purity of over 99.2%. The titanium source raw materials include titanium concentrate, titanium corundum, high-titanium slag, and other powders with high titanium content.

4. A novel high thermal conductivity TiN / Ti(C) as described in claim 2 or 3 x N 1-x Sialon-SiC composite refractory material, characterized in that: The silicon carbide has four particle sizes: 2.5-1.43 mm, 1.43-0.5 mm, 0.5-0 mm, and ≤0.074 mm. The silicon powder has a particle size ≤0.074 mm, the α-Al₂O₃ micro powder has a particle size D50 ≤10 μm, and the titanium source raw material has a particle size ≤0.074 mm. The proportions of different particle sizes are as follows: 2.5 ≤ particle size < 1.43 mm 10-20%, 1.43 ≤ particle size < 0.5 mm 30-50%, 0.5 ≤ particle size < 0 mm 15-30%, and particle size ≤0.074 mm 15-30%.