Metallurgical bonded thick layer composite ceramic blast furnace tuyere

Abstract

The present application provides a kind of metallurgical combination thick layer composite ceramic blast furnace cannon mouth, it is related to iron-making blast furnace front equipment technical field, including cannon mouth body and replaceable cannon mouth cap embedded in its front end inner hole;Cannon mouth body is ladder shaft structure, outer circle is first outer circle section, second outer circle section, connecting section and mounting flange in turn, coaxial ladder inner hole is arranged in it;Cannon mouth cap is flange bush structure, bush inserts body bush mounting inner hole and forms clearance fit, flange end surface is positioned axially, and self-tightening effect is formed using cannon clay counter pressure during work;The body front end 122mm range and cannon mouth cap whole are the metallurgical combination composite material of high-chromium cast iron cast-infiltration alumina ceramic, working layer ceramic accounts for 60%~65%, and radial thickness is 15mm;Mud inlet hole is provided with long circular positioning key groove to realize circumferential anti-rotation.The ceramic combination strength of the present application is 150MPa, the average life reaches 174 furnaces, the single replacement of cannon mouth cap is 3 minutes, there is no problem of falling and mud leakage, and the cost of blast furnace spare parts and shutdown is significantly reduced.

Description

Technical Field

[0001] This invention relates to the field of blast furnace front equipment technology, and in particular to a metallurgically bonded thick-layer composite ceramic blast furnace nozzle. Background Technology

[0002] Blast furnace mud guns are core furnace-front equipment used to seal the taphole in ironmaking production. The nozzle, as the front end of the mud gun, directly contacts molten iron at temperatures above 1500°C and is a key vulnerable component that transports mud to seal the taphole. Its lifespan and structural reliability directly determine the continuous production efficiency of the blast furnace and the safety of furnace-front operations.

[0003] Traditional nozzles are mostly made of a single high-chromium cast iron material, which is very easy to burn and crack under the continuous scouring of high-temperature molten iron and repeated rapid heating and cooling. On average, they can only be used for 3 heats before they must be replaced. A single blast furnace can be shut down for more than 20 hours a year due to nozzle replacement, resulting in high spare parts costs and downtime losses. At the same time, the frequent replacement of nozzles by furnace workers in high-temperature and molten iron splashing areas significantly increases the safety risk of burns and scalds.

[0004] To improve the lifespan of the nozzle, existing technologies mainly focus on two areas of improvement, but both have significant drawbacks: 1. Split-type metal nozzle cap structure: The nozzle is divided into a body and a replaceable metal cap at the front end, which reduces the cost of spare parts to a certain extent. However, the metal cap itself does not have a fundamental improvement in high temperature erosion resistance, and its average lifespan is only 8 to 10 heats. Moreover, most of the existing external nozzle caps use threaded or bolted connections. The threads are prone to sintering and rusting at high temperatures, and the replacement time is as long as 20 minutes or more. At the same time, there is no reliable axial positioning, and it is very easy to fall off due to the erosion of molten iron and the back pressure of the gun clay, resulting in nozzle blockage failure and fire accidents.

[0005] 2. Surface ceramic coating structure: A 0.2~0.5mm thick alumina ceramic layer is prepared on the working surface of the nozzle using a thermal spraying process, which can extend the service life to about 75 heats. However, the coating layer and the metal substrate are purely mechanically bonded, and the bonding strength is less than 10MPa. Under thermal stress and molten iron erosion, it is very easy to peel off in pieces. The thin coating layer cannot withstand long-term molten iron erosion, and there is an insurmountable bottleneck in extending the service life.

[0006] Furthermore, existing nozzles generally suffer from two structural design flaws: First, there is no circumferential positioning structure between the nozzle and the mud-blasting sleeve. The reaction force of mud blasting causes the nozzle to rotate circumferentially, resulting in misalignment between the nozzle and the taphole, leading to mud overflow and incomplete clogging. Second, replaceable components all use additional connectors, which not only increases costs but also increases the risk of detachment due to connector failure at high temperatures. There has long been a technical bias in this field: the belief that ceramic layer thickness exceeding 2mm will crack under rapid heating and cooling due to mismatched thermal expansion coefficients has prevented breakthroughs in thin coating limitations; simultaneously, the belief that replaceable components must use threaded or bolted mechanical connectors to ensure reliable connections has also failed to address the issue of connector failure at high temperatures. Summary of the Invention

[0007] The purpose of this invention is to address the shortcomings of existing technologies by providing a metallurgically integrated thick-layer composite ceramic blast furnace nozzle, which solves the technical problems of short lifespan, easy detachment of ceramic layer, easy detachment of nozzle cap, easy circumferential rotation, and low replacement efficiency of traditional nozzles.

[0008] A metallurgically bonded thick-layer composite ceramic blast furnace nozzle includes a nozzle body and a replaceable nozzle cap embedded in the inner hole at the front end of the nozzle body. The nozzle body is a stepped shaft structure extending axially, with the front end being the working end that contacts the molten iron and the rear end being the mounting end that connects to the mud gun. The outer circle of the nozzle body consists of a first outer circle segment, a second outer circle segment, a connecting segment, and a mounting flange, from the front end to the rear end. The first outer circle segment has a diameter of 275~285mm and an axial length of 58~64mm, with a C2 chamfer at the front end. The second outer circle segment has a diameter of 165~175mm. The connecting segment has a diameter of 235~245mm. The mounting flange has a diameter of 295~305mm and is located at the rear end of the nozzle body. The nozzle body has a coaxial stepped inner hole, consisting of a bushing mounting inner hole, a mud discharge inner hole, and a mud inlet inner hole, arranged sequentially from the front end to the rear end. The bushing mounting inner hole has a diameter of 188-192mm and an axial depth of 24-26mm, extending from the front end to the rear. The mud discharge inner hole has a diameter of 168-172mm and is coaxially connected to the bushing mounting inner hole. The mud inlet inner hole has a diameter of 208-212mm, with a C15 inner chamfer at the rear end opening and an axial depth of 48-52mm. The nozzle cap is a flanged bushing structure, including a front flange and a rearwardly extending liner. The outer diameter of the flange is 275-285mm, and the axial thickness is 28-32mm. The outer diameter of the liner is 188-192mm, and the axial length is 24-26mm. The rear end of the liner has an R3 chamfer. The nozzle cap has a coaxial through-hole with a diameter of 168-172mm. The transition between the flange and the liner has an R2 fillet. During assembly, the nozzle cap is inserted into the bushing mounting hole from the front end of the nozzle body. The outer circle of the bushing body and the bushing mounting hole form a clearance fit. The rear end face of the flange fits against the front end face of the first outer circle section of the nozzle body to achieve axial positioning. After assembly, the outer circle of the flange is flush with the outer circle of the first outer circle section of the nozzle body. The inner hole of the nozzle cap and the mud outlet inner hole of the nozzle body are coaxial and of equal diameter and connected to form a complete mud channel. During operation, the mud back pressure acts on the flange to form an axial self-tightening effect. The greater the pressure, the tighter the fit. The solid portion of the nozzle body, extending axially from the front end face within a length of 118-126mm, and the entire nozzle cap are all metallurgically bonded composite materials with a high-chromium cast iron matrix and alumina ceramic particles infiltrated into it. Among them, the working area of ​​the nozzle cap and the inner wall of the nozzle body bushing with a radial thickness of 14-16mm outwards has an alumina ceramic particle volume ratio of 60%-65%, forming a thick, wear-resistant, and high-temperature resistant working layer. The inner wall of the nozzle body is provided with an elongated oval positioning keyway, which is used to cooperate with the mud gun's mud-beating sleeve to achieve circumferential positioning and prevent the nozzle from rotating circumferentially during mud-beating.

[0009] Furthermore, the alumina ceramic particles have a particle size of 1~3mm, the high-chromium cast iron molten metal is poured at a temperature of 1450~1500℃ during casting, and after cooling, the ceramic particles and the high-chromium cast iron matrix form a metallurgical bonding interface without mechanical gaps, with a bonding strength of 150MPa.

[0010] Furthermore, the fitting clearance between the outer circle of the nozzle cap liner and the inner hole of the nozzle body bushing is 0.05~0.15mm, and the mating surfaces are coated with silicone sealant resistant to 1500℃ during assembly.

[0011] Furthermore, in the radial solid area corresponding to the first outer circular section of the nozzle body, that is, the base part between the bushing mounting inner hole and the outer circle of the first outer circular section excluding the 15mm thick working layer, the volume ratio of alumina ceramic particles is 20%~30%, forming a gradient composite structure that takes into account both structural strength and high temperature erosion resistance.

[0012] Furthermore, the axial width of the oblong positioning keyway is 24~26mm, the circumferential length is 70~110mm, and the radial depth between the bottom of the groove and the surface of the mud inlet hole is 7~9mm.

[0013] Furthermore, after assembly, the front end face of the nozzle cap flange is flat, without any protrusions or flash.

[0014] Furthermore, the mounting flange of the nozzle body is provided with four circumferentially distributed 22mm mounting bolt holes for fixing to the mud gun body by bolts.

[0015] Furthermore, the chromium content of the high-chromium cast iron matrix is ​​12% to 15% by mass.

[0016] This invention also provides a method for preparing the above-mentioned metallurgically bonded thick-layer composite ceramic blast furnace nozzle, comprising the following steps: S1. Mold preparation: The mold for the nozzle body and nozzle cap is prepared by the lost-wax method. Alumina ceramic particles are pre-laid in the cavity of the mold corresponding to the composite material area: pure alumina ceramic particles with a particle size of 1~3mm are laid in the working layer area, and a mixture of alumina ceramic particles and high chromium cast iron powder with a mass ratio of 3:7 is laid in the remaining matrix area. S2. Casting and Infiltration: Preheat the mold to 780~820℃ and pour high-chromium cast iron liquid at a temperature of 1470~1490℃. Under negative pressure, the molten iron completely penetrates the gaps between ceramic particles. After holding at the temperature for 1.8~2.2 hours, it is cooled with the furnace. The ceramic particles and the high-chromium cast iron matrix form a metallurgical bonding interface. S3. Machining: The cast blank is precision machined according to the drawing requirements, and the dimensional tolerances of each mating surface are strictly controlled to ensure that the mating clearance is within the range of 0.05~0.15mm. S4. Assembly: Before assembly, apply a layer of silicone sealant resistant to 1500℃ evenly to the outer surface of the nozzle cap liner. Align the liner with the bushing mounting hole and guide it slowly from the front end using the R3 guide chamfer until the rear end face of the flange is completely in contact with the front end face of the first outer circle.

[0017] This invention provides a metallurgically bonded thick-layer composite ceramic blast furnace nozzle, which has the following beneficial effects: This invention employs a casting-infiltration metallurgical combination process to prepare a 15mm thick working layer with a high ceramic content. The ceramic layer thickness is 30 to 75 times that of traditional thermal spray coatings, and the bonding strength between the ceramic and the substrate is 150MPa, which is more than 15 times that of the spray coating. It does not crack or peel off under rapid heating and cooling. The gradient composite structure effectively alleviates thermal stress, and the thermal shock stability is increased from 50 cycles to more than 500 cycles compared to traditional products. The average service life in field applications reaches 174 heats, which is 58 times that of traditional high-chromium cast iron nozzles and 2.3 times that of thermally sprayed ceramic nozzles.

[0018] The nozzle cap of this invention adopts an embedded bushing structure. The bushing is inserted into the inner hole for fit and is axially positioned on the flange end face. During operation, the nozzle is pressed tightly against the taphole mud sleeve. Combined with the axial back pressure of the high-pressure taphole mud, a self-tightening effect is formed. The greater the pressure, the tighter the fit, which fundamentally eliminates the risk of the outer cap being washed off by molten iron. There are no bolts, threads or other easily sintered connecting parts. When replacing, the old cap can be removed by simply prying the flange. After cleaning the residual adhesive on the mating surface, the new cap can be inserted. The replacement time for a single cap is no more than 3 minutes, which is 85% shorter than the traditional external bolt structure, and significantly reduces the working time of furnace workers in high-temperature areas.

[0019] This invention features an elongated oval positioning keyway in the mud inlet hole, which works in conjunction with the positioning key of the mud gun's mud-beating sleeve. During the mud-beating process, the nozzle does not rotate circumferentially, ensuring that the nozzle and the iron outlet are always aligned, achieving a 100% success rate in plugging the outlet and preventing mud overflow and fire accidents.

[0020] This invention features a replaceable nozzle cap, which is the most vulnerable part at the very front. After wear, the entire nozzle body does not need to be replaced, reducing spare parts costs by more than 60%. The mating clearance is controlled at 0.05~0.15mm and coated with high-temperature sealant, eliminating problems such as mud leakage and iron leakage, and significantly improving sealing reliability. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings of the embodiments will be briefly described below.

[0022] The accompanying drawings described below are only related to some embodiments of the invention and are not intended to limit the invention.

[0023] In the attached diagram: Figure 1 This is a cross-sectional view of the nozzle cap in this invention; Figure 2 This is a cross-sectional structural diagram of the nozzle body in this invention; Figure 3 This is a schematic cross-sectional view of the overall structure of the nozzle body and nozzle cap after assembly according to the present invention.

[0024] List of reference numerals 1. Nozzle body; 11. First outer circular section; 12. Second outer circular section; 13. Connecting section; 14. Mounting flange; 15. Bushing mounting inner hole; 16. Mud discharge inner hole; 17. Mud inlet inner hole; 18. Elongated oval positioning keyway; 2. Nozzle cap; 21. Flange; 22. Liner. Detailed Implementation

[0025] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. This embodiment is applied to a hydraulic mud gun in a 1280m blast furnace and does not constitute a limitation on the present invention.

[0026] Example 1: Please refer to Figures 1 to 3 : I. Structural Design A metallurgically bonded thick-layer composite ceramic blast furnace nozzle includes a nozzle body 1 and a replaceable nozzle cap 2 embedded in the inner hole at the front end of the nozzle body 1.

[0027] The nozzle body 1 is a stepped shaft structure extending axially, with the front end being the working end that contacts the molten iron and the rear end being the mounting end that connects to the mud gun. The outer circle of the nozzle body 1 consists of a first outer circle segment 11, a second outer circle segment 12, a connecting segment 13, and a mounting flange 14, from the front end to the rear end. The first outer circle segment 11 has a diameter of 280 mm, a tolerance of 0.1 mm, an axial length of 61 mm, and a C2 external chamfer at the front end of the outer circle. The second outer circle segment 12 has a diameter of 170 mm and a tolerance of 0.1 mm. The connecting segment 13 has a diameter of 240 mm. The mounting flange 14 has a diameter of 300 mm and is located at the rear end of the nozzle body 1. The flange has four circumferentially distributed 22 mm mounting bolt holes.

[0028] The nozzle body 1 has a coaxial stepped inner hole, which consists of a bushing mounting inner hole 15, a mud discharge inner hole 16, and a mud inlet inner hole 17, arranged sequentially from the front end to the rear end. The bushing mounting inner hole 15 has a diameter of 190mm, a tolerance of +0.1mm / -0.05mm, an axial depth of 25mm, and extends from the front end to the rear. The mud discharge inner hole 16 has a diameter of 170mm and is coaxially connected with the bushing mounting inner hole 15. The mud inlet inner hole 17 has a diameter of 210mm, a C15 inner chamfer at the rear end, and an axial depth of 50mm.

[0029] The nozzle cap 2 is a flanged bushing structure, including a front flange portion 21 and a rearwardly extending liner portion 22; the outer diameter of the flange portion 21 is 280mm and the axial thickness is 30mm; the outer diameter of the liner portion 22 is 190mm, the tolerance is 0 / -0.3mm, the axial length is 25mm, and the rear end of the liner portion 22 is provided with an R3 chamfer; the nozzle cap 2 has a coaxial through hole with a diameter of 170mm; the transition between the flange portion 21 and the liner portion 22 is provided with an R2 fillet.

[0030] During assembly, the nozzle cap 2 is inserted into the bushing mounting inner hole 15 from the front end of the nozzle body 1. The outer circle of the bushing part 22 and the bushing mounting inner hole 15 form a clearance fit of 0.05~0.15mm. The rear end face of the flange part 21 fits against the front end face of the first outer circle section 11 of the nozzle body 1 to achieve axial positioning. After assembly, the outer circle of the flange part 21 is flush with the outer circle of the first outer circle section 11 of the nozzle body 1. The 170mm inner hole of the nozzle cap 2 is coaxial and of equal diameter with the 170mm mud discharge inner hole 16 of the nozzle body 1, forming a complete mud discharge channel.

[0031] The solid portion of the nozzle body 1, extending axially within 122mm from the front end face, and the entire nozzle cap 2, are all metallurgically bonded composite materials made of high-chromium cast iron matrix infiltrated with alumina ceramic particles. Among them, the entire nozzle cap 2 and the working area of ​​the nozzle body 1 bushing mounting inner hole 15 with a radial thickness of 15mm have an alumina ceramic particle volume ratio of 62%, forming a thick, wear-resistant, and high-temperature resistant working layer; the outer matrix area has an alumina ceramic particle volume ratio of 25%, forming a gradient composite structure.

[0032] The inner wall of the nozzle body 1, which has a mud inlet hole 17, is provided with an elongated oval positioning keyway 18 with an axial groove width of 25mm, a circumferential groove length of 90mm, and a groove depth of 8mm. This keyway is used to cooperate with the mud gun's mud-spraying sleeve to achieve circumferential positioning.

[0033] II. Preparation Process 1. Casting of the Nozzle Body 1: The lost-wax casting method was used to prepare the mold. Alumina ceramic particles were pre-laid in the cavity corresponding to the front end of the nozzle body 1 (122mm in length). Specifically, pure alumina ceramic particles with a particle size of 1-3mm were laid in the working area radially outward from the inner wall of the bushing mounting hole 15, ensuring that the ceramic volume ratio in this area was 62% after casting. The remaining matrix area was laid with a mixture of alumina ceramic particles and high-chromium cast iron powder in a mass ratio of 3:7, ensuring that the ceramic volume ratio in this area was 25% after casting. After the ceramic particles were laid, the mold was preheated to 800℃, and high-chromium cast iron liquid (chromium content 13.5%) was poured at a temperature of 1480℃. Under negative pressure, the molten iron completely penetrated the gaps between the ceramic particles. After holding at this temperature for 2 hours, it was cooled with the furnace. The ceramic particles and the high-chromium cast iron matrix formed a metallurgical bonding interface. The bonding strength was tested to be 162MPa, with no porosity or slag inclusions.

[0034] 2. Casting and forming of nozzle cap 2: The same casting and infiltration process is used to prepare the blank of nozzle cap 2. The volume ratio of ceramic particles in the whole blank is 60%. After cooling, the sand is removed and it is ready for processing.

[0035] 3. Machining: The cast blanks are precision machined according to the drawings, and the dimensional tolerances are strictly controlled: the diameter tolerance of the inner hole 15 of the bushing is +0.08mm / -0.03mm, and the outer diameter tolerance of the liner part 22 of the nozzle cap 2 is 0 / -0.1mm, ensuring that the fit clearance is within the range of 0.05~0.15mm.

[0036] 4. Assembly: Before assembly, apply a layer of high-temperature silicone sealant resistant to 1500℃ evenly to the outer surface of the liner 22 of the nozzle cap 2. Align the liner 22 with the bushing mounting inner hole 15 of the nozzle body 1. Guided by the R3 guide chamfer, slowly insert it from the front end until the rear end face of the flange 21 is completely in contact with the front end face of the first outer circular section 11.

[0037] III. Application Effects The nozzle of this embodiment underwent a three-month industrial test in a 1280m blast furnace of a steel plant: the average service life of a single nozzle was 174 heats, which is 58 times that of traditional high-chromium cast iron nozzles; the thermal shock stability reached 520 cycles, with no problems such as ceramic layer peeling, nozzle cap 2 falling off, or circumferential rotation, and the plugging success rate was 100%; replacing nozzle cap 2 only takes 2.5 minutes, which is 87% shorter than the traditional structure, and the application effect is good.

[0038] Comparative Example 1: The same structure as in Example 1 was used, but the ceramic layer was prepared using a thermal spraying process with a thickness of 0.5 mm. Testing showed that the coating-substrate bonding strength was only 8 MPa, and the average lifespan in field applications was 72 heats, with localized coating peeling occurring after only 45 heats.

[0039] Comparative Example 2: The same material as in Example 1 was used, but the nozzle cap 2 adopted a traditional external threaded connection structure. In field applications, there were 3 instances of thread sintering that made disassembly impossible, with an average replacement time of 22 minutes; and there was also one incident where the nozzle cap 2 was washed off by molten iron.

[0040] Comparative Example 3: It uses the same materials and structure as Example 1, but does not have a positioning keyway. In field applications, eight instances of nozzle circumferential rotation caused misalignment and mud leakage, resulting in a nozzle plugging success rate of only 87%.

[0041] The above are merely preferred embodiments of the present invention. Any equivalent substitutions or improvements made based on the principles of the present invention shall fall within the protection scope of the present invention.

Claims

1. A metallurgically bonded thick-layer composite ceramic blast furnace nozzle, characterized in that, Includes a cannon body (1) and a replaceable cannon cap (2) fitted into the inner hole at the front end of the cannon body (1). The nozzle body (1) is a stepped shaft structure extending along the axial direction. The front end is the working end that contacts the molten iron, and the rear end is the mounting end that connects to the mud gun. The outer circle of the nozzle body (1) consists of a first outer circle section (11), a second outer circle section (12), a connecting section (13), and a mounting flange (14) from the front end to the rear end. The first outer circular section (11) has a diameter of 275~285mm and an axial length of 58~64mm, and the front end of the outer circle is provided with a C2 outer chamfer; the second outer circular section (12) has a diameter of 165~175mm; the connecting section (13) has a diameter of 235~245mm; the mounting flange (14) has a diameter of 295~305mm and is located at the rear end of the nozzle body (1); The nozzle body (1) has a coaxial stepped inner hole, which consists of a bushing mounting inner hole (15), a mud discharge inner hole (16), and a mud inlet inner hole (17) from the front end to the rear end. The bushing mounting inner hole (15) has a diameter of 188~192mm and an axial depth of 24~26mm, extending from the front end to the rear. The mud discharge inner hole (16) has a diameter of 168~172mm and is coaxially connected with the bushing mounting inner hole (15). The mud inlet inner hole (17) has a diameter of 208~212mm, and the rear end opening is provided with a C15 inner chamfer, with an axial depth of 48~52mm. The nozzle cap (2) is a flanged bushing structure, including a front flange (21) and a rearwardly extending liner (22); the outer diameter of the flange (21) is 275~285mm and the axial thickness is 28~32mm; the outer diameter of the liner (22) is 188~192mm and the axial length is 24~26mm, and the rear end of the liner (22) is provided with an R3 chamfer; the nozzle cap (2) has a coaxial through hole with a diameter of 168~172mm; the transition between the flange (21) and the liner (22) is provided with an R2 fillet; During assembly, the nozzle cap (2) is inserted into the bushing mounting inner hole (15) from the front end of the nozzle body (1). The outer circle of the bushing part (22) and the bushing mounting inner hole (15) form a clearance fit. The rear end face of the flange part (21) fits against the front end face of the first outer circle section (11) of the nozzle body (1) to achieve axial positioning. After assembly, the outer circle of the flange part (21) is flush with the outer circle of the first outer circle section (11) of the nozzle body (1). The inner hole of the nozzle cap (2) and the mud outlet inner hole (16) of the nozzle body (1) are coaxial and connected with the same diameter to form a complete mud channel. During operation, the mud back pressure acts on the flange part (21) to form an axial self-tightening effect. The solid part of the nozzle body (1) with an axial length of 118~126mm from the front end face, and the nozzle cap (2) as a whole, are all metallurgically bonded composite materials with high chromium cast iron matrix and alumina ceramic particles; wherein the nozzle cap (2) as a whole and the working area of ​​the inner hole (15) of the nozzle body (1) bushing with a radial thickness of 14~16mm have alumina ceramic particles accounting for 60%~65% of the volume, forming a thick wear-resistant and high-temperature resistant working layer; The nozzle body (1) has an elongated oval positioning keyway (18) on the wall of the mud inlet hole (17), which is used to cooperate with the mud gun's mud-beating sleeve to achieve circumferential positioning and prevent the nozzle from rotating circumferentially during mud-beating.

2. The metallurgically bonded thick-layer composite ceramic blast furnace nozzle according to claim 1, characterized in that, The alumina ceramic particles have a particle size of 1~3mm. The pouring temperature of the high-chromium cast iron liquid during casting is 1450~1500℃. After cooling, the ceramic particles and the high-chromium cast iron matrix form a metallurgical bonding interface with a bonding strength of 150MPa.

3. The metallurgically bonded thick-layer composite ceramic blast furnace nozzle according to claim 1, characterized in that, The fitting clearance between the outer circle of the liner part (22) of the nozzle cap (2) and the bushing mounting inner hole (15) of the nozzle body (1) is 0.05~0.15mm. During assembly, the mating surfaces are coated with silicone sealant resistant to high temperature of 1500℃.

4. The metallurgically bonded thick-layer composite ceramic blast furnace nozzle according to claim 1, characterized in that, The radial solid area corresponding to the first outer circular section (11) of the nozzle body (1), that is, the base part between the bushing mounting inner hole (15) and the outer circle of the first outer circular section (11) excluding the 15mm thick working layer, has an alumina ceramic particle volume ratio of 20%~30%, forming a gradient composite structure that takes into account both structural strength and high temperature erosion resistance.

5. The metallurgically bonded thick-layer composite ceramic blast furnace nozzle according to claim 1, characterized in that, The axial width of the oblong positioning keyway (18) is 24~26mm, the circumferential length is 70~110mm, and the radial depth between the bottom of the keyway and the surface of the mud inlet hole (17) is 7~9mm.

6. The metallurgically bonded thick-layer composite ceramic blast furnace nozzle according to claim 1, characterized in that, After assembly, the front end face of the flange (21) of the nozzle cap (2) is flat, without protrusions or burrs.

7. The metallurgically bonded thick-layer composite ceramic blast furnace nozzle according to claim 1, characterized in that, The nozzle body (1) has four circumferentially distributed 22mm mounting bolt holes on its mounting flange (14) for fixing to the mud gun body with bolts.

8. The metallurgically bonded thick-layer composite ceramic blast furnace nozzle according to claim 2, characterized in that, The chromium content of the high-chromium cast iron matrix is ​​12% to 15% by mass.

9. A method for preparing a metallurgically bonded thick-layer composite ceramic blast furnace nozzle as described in any one of claims 1 to 8, characterized in that, Includes the following steps: S1. Mold preparation: The molds for the nozzle body (1) and nozzle cap (2) are prepared by the lost-wax method. Alumina ceramic particles are pre-laid in the cavity of the mold corresponding to the composite material area: pure alumina ceramic particles with a particle size of 1~3mm are laid in the working layer area, and a mixture of alumina ceramic particles and high chromium cast iron powder with a mass ratio of 3:7 is laid in the other matrix areas. S2. Casting and Infiltration: Preheat the mold to 780~820℃ and pour high-chromium cast iron liquid at a temperature of 1470~1490℃. Under negative pressure, the molten iron completely penetrates the gaps between ceramic particles. After holding at the temperature for 1.8~2.2 hours, it is cooled with the furnace. The ceramic particles and the high-chromium cast iron matrix form a metallurgical bonding interface. S3. Machining: The cast blank is precision machined according to the drawing requirements, and the dimensional tolerances of each mating surface are strictly controlled to ensure that the mating clearance is within the range of 0.05~0.15mm; S4. Assembly: Before assembly, apply a layer of silicone sealant resistant to 1500℃ to the outer surface of the liner (22) of the nozzle cap (2). Align the liner (22) with the bushing mounting inner hole (15) and slowly insert it from the front end by relying on the R3 guide chamfer until the rear end face of the flange (21) is completely in contact with the front end face of the first outer circle (11).

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