A split nanocrystalline alloy steel casting trough and its preparation method

Abstract

The present invention discloses a split nanocrystalline alloy steel casting trough and a preparation method thereof. The split nanocrystalline alloy steel casting trough is formed by splicing a graphite runner trough located at the rear section and a corundum steel casting head located at the front section. The graphite runner trough is made of graphite, and the corundum steel casting head is made of plate-shaped corundum. The graphite runner trough and the corundum steel casting head are detachably connected via an overlap structure. The present invention adopts a detachable and replaceable split structure design, dividing the nanocrystalline alloy steel casting trough into two, and splicing the graphite runner trough and the corundum steel casting head made of different materials. The two sections of the structure can be replaced independently, avoiding local damage that requires replacement of the entire structure. In addition, the present invention fully utilizes the advantages of corundum and graphite materials, which not only controls costs but also avoids molten steel adhering to the runner trough, thereby solving the shortcomings of existing integral graphite nanocrystalline alloy steel casting troughs, such as short service life and easy adhesion of molten steel to the integral corundum nanocrystalline alloy steel casting trough.

Description

Technical Field

[0001] The present invention relates to the technical field of steel casting troughs, and in particular to a split nanocrystalline alloy steel casting trough for producing and preparing nanocrystalline alloy strips and a preparation method thereof. Background Art

[0002] Nanocrystalline alloy soft magnetic materials have seen rapid development in recent years due to their excellent electromagnetic properties, high saturation magnetic induction, high squareness ratio, high magnetic permeability, low loss, and stable performance. They are particularly well-suited for high-quality core materials in switching power supplies and ISDN applications. Currently, nanocrystalline alloy strip is primarily produced using a single-roll rapid quenching process. The process involves remelting the nanocrystalline master alloy in a vacuum medium-frequency furnace. The melted molten alloy is then poured through a nanocrystalline master alloy pouring trough into a nozzle package and heated. After reaching 1400°C, the molten alloy flows from the nozzle package, passes through a nozzle and nozzle cup, and finally sprays through a nozzle onto a high-speed rotating cooling copper roller for condensation, ultimately forming a nanocrystalline alloy strip 16-30μm thick and 10-75mm wide. The nanocrystalline master alloy pouring trough is a key component of the nanocrystalline alloy strip production line. Installed at the rear of the vacuum melting furnace, it primarily pours the nanocrystalline master alloy molten steel from the vacuum melting furnace into the nozzle package, serving as a bridge between the vacuum melting furnace and the nozzle package.

[0003] The existing nanocrystalline master alloy casting trough is a one-piece type. According to the different materials, there are mainly two types:

[0004] The first type is a monolithic corundum casting trough, made entirely of plate-shaped corundum. Its advantages are its simple structure and low cost. However, it has the following disadvantages: ① The corundum casting head has a short lifespan. Under the constant erosion of high-temperature molten steel, it cracks and becomes scrapped after about a month; ② The surface of the corundum runner trough is rough, and molten steel easily adheres to the sides of the trough, making it difficult to clean; ③ After the molten steel inside the trough cools, the steel blocks will firmly adhere to the bottom wall of the corundum runner trough, making it easy to scrape the bottom wall when the steel blocks are subsequently removed, resulting in pits on the bottom wall, the formation of slag, and contamination of the molten steel.

[0005] The second type is a monolithic graphite casting trough, made entirely of graphite. This has two advantages: 1) The graphite surface is smooth, preventing molten steel from adhering to the sides of the trough; 2) Any molten steel remaining in the trough automatically separates from the bottom wall after cooling, preventing adhesion and making it easy to clean. However, there are two disadvantages: 1) The graphite casting head is relatively fragile and, under the constant impact of high-temperature molten steel, has a short lifespan, cracking and becoming scrapped within a month; 2) The manufacturing cost of a graphite casting trough is high, 5 to 6 times that of a corundum casting trough.

[0006] Therefore, there is an urgent need for a new type of steel casting trough that is relatively low in cost, has a long service life and is not prone to adhesion of molten steel on the runner groove. Summary of the Invention

[0007] The purpose of the present invention is to provide a split nanocrystalline alloy casting trough and a preparation method thereof. A detachable and replaceable split structural design is adopted to splice a graphite flow channel trough and a corundum casting head made of different materials to form a split nanocrystalline alloy casting trough. The advantages of the two materials are perfectly combined, so that the split nanocrystalline alloy casting trough has the advantages of long service life, low cost and the steel liquid is not easy to adhere to the flow channel trough. It solves the shortcomings of the existing integral graphite nanocrystalline alloy casting trough mentioned in the above background technology, such as short service life and easy adhesion of the integral corundum nanocrystalline alloy casting trough to the steel liquid.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions:

[0009] In the first aspect, the present invention provides a split nanocrystalline alloy casting trough, which is formed by splicing a graphite runner trough located in the rear section and a corundum casting head located in the front section. The graphite runner trough is made of graphite, and the corundum casting head is made of plate-shaped corundum. The graphite runner trough and the corundum casting head are detachably connected through a lap structure.

[0010] Furthermore, the graphite flow channel groove includes a horizontally distributed groove bottom, and both sides of the groove bottom and the side away from the corundum casting head are provided with upward extending groove walls, and the end of the groove bottom away from the corundum casting head is provided with a downward opening discharge pipe; the corundum casting head includes a casting head body, and the upper surface of the casting head body has a guide arc surface distributed upward away from the graphite flow channel groove, and both sides of the casting head body are respectively provided with upward extending retaining edges.

[0011] Furthermore, the central axis of the feed pipe is perpendicular to the bottom of the trough, and the feed pipe as a whole is in a cone shape with a larger upper portion and a smaller lower portion, and the taper is (1:10) to (1:20).

[0012] Furthermore, there are arc transitions between the groove wall and the groove bottom, and between the retaining edge and the casting head body.

[0013] Furthermore, the curvature of the guide arc surface is R500mm to R1000mm.

[0014] Furthermore, the overlap structure includes an upper overlap joint and a lower overlap joint that are seamlessly overlapped.

[0015] Furthermore, the upper lap joint and the lower lap joint are both distributed along the width direction of the split nanocrystalline alloy casting steel trough.

[0016] In a second aspect, the present invention provides a method for preparing the above-mentioned split nanocrystalline alloy casting trough, comprising the following steps:

[0017] S1. Preparation of graphite flow channel:

[0018] S11, crushing, screening and batching: first, the raw materials for preparing the graphite flow channel groove are crushed and screened into 1# material with a particle size of 5 mesh, 2# material with a particle size of 20 mesh, 3# material with a particle size of 100 mesh, 4# material with a particle size of 200 mesh, and 5# material with a particle size of 300 mesh; then, the crushed materials of different particle sizes are uniformly mixed according to the weight ratio of 1# material: 2# material: 3# material: 4# material: 5# material = (8-14): (12-18): (12-18): (12-18): (40-50) to obtain a first intermediate raw material;

[0019] S12, dry mixing: dry mixing the prepared first intermediate raw materials, the dry mixing time is 30min to 60min, and the dry mixing temperature is 60°C to 80°C;

[0020] S13, kneading: adding a binder and kneading at a kneading temperature of 80° C. to 95° C. for 50 min to 70 min to obtain a second intermediate raw material;

[0021] S14, molding: drying the kneaded second intermediate raw material at a temperature of 90° C. to 115° C. for 25 to 40 minutes to obtain a clay material for isostatic pressing; then, the clay material is placed into a mold of a predetermined shape and pressed using an isostatic press at a molding pressure of 20 MPa to 31 MPa and a holding time of 30 to 60 minutes to obtain an intermediate product;

[0022] S15, curing and sintering: the intermediate product is loaded into a tunnel kiln, filled with argon gas for protection and anti-oxidation roasting, the argon purity is ≥99%, the argon pressure is 0.55MPa~0.7MPa, the roasting temperature is 1000℃~1250℃, the roasting time is 48h~72h, and then naturally cooled to room temperature;

[0023] S16, graphitization: the solidified and sintered product is then placed in a high-temperature graphitization furnace for graphitization treatment. The graphitization time is 60h to 80h, and the maximum graphitization temperature is 2300℃ to 2600℃;

[0024] S17, machining: machining the outer dimensions to obtain the graphite flow channel groove;

[0025] S2. Preparation of corundum-cast steel head:

[0026] S21. Weigh the raw materials for preparing the corundum cast steel head. The corundum cast steel head is composed of the following raw materials by mass percentage: 30% to 43% of 2-6 mm granular plate-shaped corundum aggregate, 10% to 24% of 0.5-2 mm granular plate-shaped corundum aggregate, 20% to 32% of 0-0.5 mm granular plate-shaped corundum powder, 5% to 10% of metallic silicon powder, 2% to 4% of metallic aluminum powder, 5% to 10% of α-Al2O3 fine powder, 4% to 7% of binder and 3% to 6% of water.

[0027] S22, preparing co-ground powder: premixing 0-0.5 mm plate-shaped corundum powder, metallic silicon powder, metallic aluminum powder and α-Al2O3 fine powder, and co-grinding for 30-40 minutes to form co-ground powder;

[0028] S23, preparing the mud material: mixing 2-6 mm plate-shaped corundum aggregate and 0.5-2 mm plate-shaped corundum aggregate for 3-5 minutes, then adding the co-ground powder obtained in step S22, adding water and a binder, and mixing and stirring evenly to obtain a wet material for the corundum casting steel head;

[0029] S24, molding: The embryo wet material is placed into a mold, and placed in an overhead vibration pressure molding machine for vibration, pressure, and ramming to form the embryo;

[0030] S25, drying: after demoulding, drying the formed steel head blank at a temperature of 120° C. to 135° C., heating time of 1 hour, and keeping the temperature at 120° C. to 135° C. for 9 hours to 12 hours;

[0031] S26, sintering: put the dried steel head blank into the nitriding furnace for sintering. The nitriding sintering temperature is 1400℃~1550℃, the heating time is 11 hours, and the temperature is kept at 1400℃~1550℃ for 11h~13h. The nitrogen flow rate is 11m 3 / h~12m 3 / h; after sintering, take it out and cool it to obtain the corundum cast steel head;

[0032] S3. Splice the graphite runner trough and the corundum casting steel head to obtain a split nanocrystalline alloy casting steel trough.

[0033] Furthermore, in step S11, the raw material for preparing the graphite flow channel groove is a non-graphitized carbon material with a carbon content of ≥99%, an ash content of ≤0.35%, a volatile matter of ≤0.4%, and a sulfur content of ≤0.16%.

[0034] Furthermore, in step S13, the binder used to prepare the graphite flow channel groove is any one of polyurethane resin, silicone resin, and polyimide, and the amount of the binder accounts for 6% to 13% of the total amount of the first intermediate raw material.

[0035] Furthermore, in step S21, the index requirements for the raw materials used to prepare the corundum cast steel head are as follows: the Al2O3 content in the plate-shaped corundum aggregate is ≥99%, the Fe2O3 content is ≤0.2%, and the Na2O content is ≤0.37%; the Si content in the metallic silicon powder is ≥98%; the α-Al2O3 content in the α-Al2O3 micropowder is ≥98%, and the particle size is ≤1 micron; the Al content in the metallic aluminum powder is ≥99%.

[0036] Furthermore, in step S21, the binder used to prepare the corundum cast steel head is any one of polyvinyl alcohol (ie PVA), ethylene-vinyl alcohol copolymer (ie PVOH), and clay.

[0037] Compared with the prior art, the present invention provides a split nanocrystalline alloy steel casting trough and a preparation method thereof, which has the following beneficial effects:

[0038] The present invention adopts a detachable and replaceable split structural design, dividing the nanocrystalline alloy casting trough into two, and splicing the graphite runner trough and the corundum casting head made of different materials. The corundum casting head located at the front section and the graphite runner trough located at the rear section can be replaced independently, avoiding the need for overall replacement due to local damage.

[0039] Because the front-end casting head has a short lifespan, it is made of inexpensive corundum, reducing the cost of frequent replacements. Meanwhile, the back-end runner trough has a long lifespan and is made of relatively expensive graphite, reducing the cost of less frequent replacements. This invention leverages the advantages of both corundum and graphite, successfully avoiding their disadvantages, achieving an optimal combination that controls costs while preventing molten steel from adhering to the runner trough. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0041] Figure 1 This is a schematic diagram of the main cross-sectional structure of the present invention;

[0042] Figure 2 It is a schematic diagram of the top view of the structure of the present invention;

[0043] Figure 3 for Figure 1 Cross-section along the AA direction;

[0044] Figure 4 for Figure 2 Cross-section along the BB direction.

[0045] Figure numerals: 1, graphite flow channel groove; 11, groove bottom; 12, groove wall; 13, feed pipe; 14, lower lap joint; 2, corundum casting head; 21, casting head body; 22, guide arc surface; 23, rib; 24, upper lap joint. DETAILED DESCRIPTION

[0046] The technical solutions of the present invention are described clearly and completely below. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are also within the scope of protection of the present invention.

[0047] Example 1

[0048] refer to Figures 1 to 4 The present invention provides a split nanocrystalline alloy casting trough, which is formed by splicing a graphite runner trough 1 located at the rear section and a corundum casting head 2 located at the front section. The graphite runner trough 1 and the corundum casting head 2 are detachably connected through an overlapping structure.

[0049] Among them, the graphite flow channel groove 1 is made of graphite. Specifically, the graphite flow channel groove 1 includes a horizontally distributed groove bottom 11, and both sides of the groove bottom 11 and the side away from the corundum casting head 2 are provided with groove walls 12 extending upward. The end of the groove bottom 11 away from the corundum casting head is provided with a downward-opening feed pipe 13. The central axis of the feed pipe 13 is perpendicular to the groove bottom 11. The overall feed pipe 13 is in the shape of a cone with a larger top and a smaller bottom, and the taper is (1:10) to (1:20), so as to facilitate connection with the nozzle casting steel mouth. There is an arc surface transition between the groove wall 12 and the groove bottom 11 to avoid stress concentration. As an example, the purity of the graphite used to prepare the graphite flow channel groove is above 99%.

[0050] The corundum casting head 2 is made of plate-shaped corundum. Specifically, it includes a casting head body 21. The upper surface of the casting head body 21 has a flow-guiding arc surface 22 extending upward and away from the graphite flow channel 1. Upward-extending ribs 23 are provided on either side of the casting head body 21. A circular arc transition is formed between the ribs 23 and the casting head body 21 to avoid stress concentration. The curvature of the flow-guiding arc surface 22 ranges from R500mm to R1000mm, and the specific dimensions can be set according to the actual use.

[0051] In some specific embodiments, the overlap structure includes an upper overlap joint 24 and a lower overlap joint 14 that are seamlessly overlapped. Specifically, both the upper overlap joint 24 and the lower overlap joint 14 are distributed along the width of the split-type nanocrystalline alloy casting trough. As an example, in this embodiment, the upper overlap joint 24 is disposed at the end of the corundum casting head 2 adjacent to the graphite runner trough 1, and the lower overlap joint 14 is disposed at the end of the graphite runner trough 1 adjacent to the corundum casting head 2. The cross-sectional shape of both the upper overlap joint 24 and the lower overlap joint 14 is rectangular.

[0052] In this way, by adopting a split structural design, the advantages of the two materials are combined, which effectively solves the shortcomings of the existing integral graphite nanocrystalline alloy casting trough, which has a short life, and the integral corundum nanocrystalline alloy casting trough, which is easy to adhere to the molten steel.

[0053] The present invention is further described in detail below through detailed preparation examples in conjunction with the accompanying drawings.

[0054] Unless otherwise specified, the experimental and testing methods used in the preparation examples are conventional methods, and the materials, reagents, etc. used are all available from commercial channels unless otherwise specified.

[0055] Preparation Example 1

[0056] A split type nanocrystalline alloy casting trough is formed by splicing a graphite runner trough 1 at the rear section and a corundum casting head 2 at the front section. Figures 1 to 4 As shown, it is the same as Example 1, so it will not be repeated here. The specific preparation method is as follows:

[0057] S1. Preparation of graphite flow channel 1:

[0058] S11. Crushing, Screening, and Mixing: First, crush the raw materials used to prepare the graphite flow channel 1. The raw material used to prepare the graphite flow channel 1 is ungraphitized petroleum coke with a carbon content of 99.12%, an ash content of 0.12%, a volatile matter content of 0.22%, and a sulfur content of 0.11%. The raw materials are then screened into a 1# material with a particle size of 5 mesh, a 2# material with a particle size of 20 mesh, a 3# material with a particle size of 100 mesh, a 4# material with a particle size of 200 mesh, and a 5# material with a particle size of 300 mesh. The crushed materials of different particle sizes are then mixed uniformly in a weight ratio of 1# material: 2# material: 3# material: 4# material: 5# material = 12:14:15:16:43, to obtain a first intermediate raw material.

[0059] S12, dry mixing: put the prepared first intermediate raw material into a kneader for dry mixing, the dry mixing time is 45 minutes, and the dry mixing temperature is 70°C.

[0060] S13, kneading: The dry-mixed first intermediate raw material and the binder are placed in a kneader and kneaded at 90°C for 60 minutes to obtain a second intermediate raw material. The binder used to prepare the graphite flow channel groove 1 is a polyurethane resin, and its amount accounts for 8.5% of the total amount of the first intermediate raw material.

[0061] S14, molding: The second intermediate raw material obtained by kneading is dried at 103°C for 33 minutes using a drum drying equipment to obtain a clay material for isostatic pressing, the volatile matter of which is 2.97%; then, the mixed clay material is directly loaded into an epoxy resin mold of a predetermined shape, and is pressed and molded using an isostatic press with a molding pressure of 28 MPa and a holding time of 50 minutes to obtain an intermediate product.

[0062] S15. Curing and sintering: The intermediate product after isostatic pressing is loaded into a tunnel kiln and filled with argon to protect and prevent oxidation. The purity of the argon is 99.32%, the argon pressure is 0.65 MPa, the roasting temperature is 1130°C, the heating time is 52 hours, and the temperature is kept at 1130°C for 5 hours, and then naturally cooled to room temperature.

[0063] S16. Graphitization: The solidified and sintered product is then placed in a high-temperature graphitization furnace for graphitization treatment. The graphitization time is 72 hours, and the maximum graphitization temperature is 2450°C.

[0064] S17, machining: Use CNC machine tools to process into the external dimensions required by the user, and use X-ray inspection on the product to obtain the graphite flow channel groove 1.

[0065] S2. Preparation of corundum-cast steel head 2:

[0066] S21. Weigh the raw materials for preparing the corundum cast steel head 2. The corundum cast steel head 2 is composed, by mass percentage, of the following: 36% 2-6mm plate-shaped corundum aggregate, 15% 0.5-2mm plate-shaped corundum aggregate, 24% 0-0.5mm plate-shaped corundum powder, 6% metallic silicon powder, 3% metallic aluminum powder, 7% α-Al2O3 fine powder, 5% binder, and 4% water. The raw materials for preparing the corundum cast steel head are as follows: the Al2O3 content of the plate-shaped corundum aggregate is ≥99%, the Fe2O3 content is ≤0.2%, and the Na2O content is ≤0.37%; the Si content of the metallic silicon powder is ≥98%; the α-Al2O3 content of the α-Al2O3 fine powder is ≥98%, with a particle size of ≤1 micron; and the Al content of the metallic aluminum powder is ≥99%. The binder used in preparing the corundum cast steel head 2 is polyvinyl alcohol (PVA).

[0067] S22. Prepare co-ground powder: Premix 0-0.5 mm plate-shaped corundum powder, metallic silicon powder, metallic aluminum powder, and α-Al2O3 micropowder and co-grind in a ball mill for 33 minutes to form the co-ground powder. Hang five magnets below the ball mill and clean the iron filings from the magnets after each abrasive is discharged.

[0068] S23. Prepare the slurry: Mix 2-6 mm plate-shaped corundum aggregate and 0.5-2 mm plate-shaped corundum aggregate for 3-5 minutes until uniform. Then, add the co-ground powder prepared in step S22, water, and a binder. Mix and stir uniformly in a wet mill to obtain the wet material for the corundum-cast steel head. Hang at least five magnets under the wet mill. Clean the iron filings from the magnets after each milling.

[0069] S24, molding: put the embryo wet material into the mold, place it in the upper type vibration pressure molding machine, and vibrate, pressurize and ram to form it.

[0070] S25, drying: after demoulding, the formed steel head blank is placed in an electric drying furnace, heated from room temperature to 125°C, the heating time is 1 hour, and kept at 125°C for 10 hours to dry the moisture of the steel head blank.

[0071] S26, sintering: put the dried steel head blank into the nitriding furnace for sintering, raise the temperature from room temperature to 1450℃, the heating time is 11 hours, and then keep sintering at 1450℃ for 12 hours, with a nitrogen flow rate of 12m 3 / h; after sintering, take it out and cool it to obtain the corundum cast steel head 2.

[0072] S3. Finally, the prepared graphite flow channel trough 1 and the corundum casting steel head 2 are spliced ​​together to obtain a split nanocrystalline alloy casting steel trough.

[0073] Preparation Example 2

[0074] A split type nanocrystalline alloy casting trough is formed by splicing a graphite runner trough 1 at the rear section and a corundum casting head 2 at the front section. Figures 1 to 4 As shown, it is the same as Example 1, so it will not be repeated here. The specific preparation method is as follows:

[0075] S1. Preparation of graphite flow channel 1:

[0076] S11. Crushing, Screening, and Mixing: First, crush the raw materials used to prepare the graphite flow channel 1. The raw material used to prepare the graphite flow channel 1 is ungraphitized petroleum coke with a carbon content of 99.05%, an ash content of 0.15%, a volatile matter content of 0.27%, and a sulfur content of 0.12%. The raw materials are then screened into a 1# material with a particle size of 5 mesh, a 2# material with a particle size of 20 mesh, a 3# material with a particle size of 100 mesh, a 4# material with a particle size of 200 mesh, and a 5# material with a particle size of 300 mesh. The crushed materials of different particle sizes are then mixed uniformly in a weight ratio of 1# material: 2# material: 3# material: 4# material: 5# material = 10:15:15:15:45, to obtain a first intermediate raw material.

[0077] S12, dry mixing: put the prepared first intermediate raw material into a kneader for dry mixing, the dry mixing time is 50 minutes, and the dry mixing temperature is 75°C.

[0078] S13, kneading: The dry-mixed first intermediate raw material and the binder are placed in a kneader and kneaded at 87° C. for 65 minutes to obtain a second intermediate raw material. The binder used to prepare the graphite flow channel groove is silicone resin, and its amount accounts for 9.2% of the total amount of the first intermediate raw material.

[0079] S14, molding: The second intermediate raw material obtained by kneading is dried at 96°C for 28 minutes using a drum drying device to obtain a clay material for isostatic pressing, the volatile matter of which is 4.1%; then, the mixed clay material is directly loaded into an epoxy resin mold of a predetermined shape, and is pressed and molded using an isostatic press with a molding pressure of 26 MPa and a holding time of 55 minutes to obtain an intermediate product.

[0080] S15. Curing and sintering: The intermediate product after isostatic pressing is loaded into a tunnel kiln and filled with argon to protect and prevent oxidation for roasting. The purity of argon is 99.48%, the pressure of argon is 0.64 MPa, the roasting temperature is 1220°C, the heating time is 55h, and the temperature is kept at 1220°C for 7h, and then naturally cooled to room temperature.

[0081] S16. Graphitization: The solidified and sintered product is then placed in a high-temperature graphitization furnace for graphitization treatment. The graphitization time is 69 hours, and the maximum graphitization temperature is 2530°C.

[0082] S17, machining: Use CNC machine tools to process into the external dimensions required by the user, and use X-ray inspection on the product to obtain the graphite flow channel groove 1.

[0083] S2. Preparation of corundum-cast steel head 2:

[0084] S21. Weigh the raw materials for preparing the corundum cast steel head 2. The corundum cast steel head 2 is composed, by mass percentage, of the following: 32% 2-6mm plate-shaped corundum aggregate, 12% 0.5-2mm plate-shaped corundum aggregate, 26% 0-0.5mm plate-shaped corundum powder, 7% metallic silicon powder, 4% metallic aluminum powder, 8% α-Al2O3 fine powder, 6% binder, and 5% water. The raw materials for preparing the corundum cast steel head must meet the following requirements: the Al2O3 content of the plate-shaped corundum aggregate must be ≥99%, the Fe2O3 content must be ≤0.2%, and the Na2O content must be ≤0.37%; the Si content of the metallic silicon powder must be ≥98%; the α-Al2O3 content of the α-Al2O3 fine powder must be ≥98%, with a particle size of ≤1 micron; and the Al content of the metallic aluminum powder must be ≥99%. The binder used in preparing the corundum cast steel head is ethylene-vinyl alcohol copolymer (PVOH).

[0085] S22. Prepare co-ground powder: Premix 0-0.5 mm plate-shaped corundum powder, metallic silicon powder, metallic aluminum powder, and α-Al2O3 micropowder and co-grind in a ball mill for 33 minutes to form the co-ground powder. Hang five magnets below the ball mill and clean the iron filings from the magnets after each abrasive is discharged.

[0086] S23. Prepare the slurry: Mix 2-6 mm plate-shaped corundum aggregate and 0.5-2 mm plate-shaped corundum aggregate for 3-5 minutes until uniform. Then, add the co-ground powder prepared in step S22, water, and a binder. Mix and stir uniformly in a wet mill to obtain the wet material for the corundum-cast steel head. Hang at least five magnets under the wet mill. Clean the iron filings from the magnets after each milling.

[0087] S24, molding: put the embryo wet material into the mold, place it in the upper type vibration pressure molding machine, and vibrate, pressurize and ram to form it.

[0088] S25, drying: after demoulding, the formed steel head blank is placed in an electric drying furnace, heated from room temperature to 130°C, the heating time is 1 hour, and kept at 130°C for 11 hours to dry the moisture of the steel head blank.

[0089] S26, sintering: put the dried steel head blank into the nitriding furnace for sintering, heating from room temperature to 1500℃, heating time 11 hours, then sintering at 1450℃ for 11 hours, nitrogen flow rate 11m 3 / h; after sintering, take it out and cool it to obtain the corundum-cast steel head 2.

[0090] S3. Finally, the prepared graphite flow channel trough 1 and the corundum casting steel head 2 are spliced ​​together to obtain a split nanocrystalline alloy casting steel trough.

[0091] Preparation Example 3

[0092] A split type nanocrystalline alloy casting trough is formed by splicing a graphite runner trough 1 at the rear section and a corundum casting head 2 at the front section. Figures 1 to 4 As shown, it is the same as Example 1, so it will not be repeated here. The specific preparation method is as follows:

[0093] S1. Preparation of graphite flow channel 1:

[0094] S11. Crushing, Screening, and Mixing: First, crush the raw materials used to prepare the graphite flow channel 1. The raw material used to prepare the graphite flow channel 1 is ungraphitized petroleum coke with a carbon content of 99.38%, an ash content of 0.32%, a volatile matter content of 0.33%, and a sulfur content of 0.14%. The raw materials are then screened into a 1# material with a particle size of 5 mesh, a 2# material with a particle size of 20 mesh, a 3# material with a particle size of 100 mesh, a 4# material with a particle size of 200 mesh, and a 5# material with a particle size of 300 mesh. The crushed materials of different particle sizes are then mixed uniformly in a weight ratio of 1# material: 2# material: 3# material: 4# material: 5# material = 13:13:13:15:46, to obtain a first intermediate raw material.

[0095] S12, dry mixing: put the prepared first intermediate raw material into a kneader for dry mixing, the dry mixing time is 57 minutes, and the dry mixing temperature is 78°C.

[0096] S13, kneading: The dry-mixed first intermediate raw material and the binder are placed in a kneader and kneaded at 93° C. for 68 minutes to obtain a second intermediate raw material. The binder used to prepare the graphite flow channel groove is a polyimide resin, and its amount accounts for 10.4% of the total amount of the first intermediate raw material.

[0097] S14, molding: The second intermediate raw material obtained by kneading is dried at 112°C for 36 minutes using a drum drying device to obtain a clay material for isostatic pressing, the volatile matter of which is 3.7%; then, the mixed clay material is directly loaded into an epoxy resin mold of a predetermined shape, and is pressed and molded using an isostatic press with a molding pressure of 30 MPa and a holding time of 48 minutes to obtain an intermediate product.

[0098] S15. Curing and sintering: The intermediate product after isostatic pressing is loaded into a tunnel kiln and filled with argon for protection and anti-oxidation roasting. The purity of argon is 99.39%, the pressure of argon is 0.59 MPa, the roasting temperature is 1190°C, the heating time is 48 hours, and the temperature is kept at 1190°C for 9 hours, and then naturally cooled to room temperature.

[0099] S16. Graphitization: The solidified and sintered product is then placed in a high-temperature graphitization furnace for graphitization treatment. The graphitization time is 69 hours, and the maximum graphitization temperature is 2390°C.

[0100] S17, machining: Use CNC machine tools to process into the external dimensions required by the user, and use X-ray inspection on the product to obtain the graphite flow channel groove 1.

[0101] S2. Preparation of corundum-cast steel head 2:

[0102] S21. Weigh the raw materials for preparing the corundum cast steel head 2. The corundum cast steel head 2 is composed, by mass percentage, of the following: 35% 2-6mm plate-shaped corundum aggregate, 12% 0.5-2mm plate-shaped corundum aggregate, 28% 0-0.5mm plate-shaped corundum powder, 5% metallic silicon powder, 3% metallic aluminum powder, 6% α-Al2O3 fine powder, 7% binder, and 4% water. The raw materials for preparing the corundum cast steel head must meet the following requirements: the Al2O3 content of the plate-shaped corundum aggregate must be ≥99%, the Fe2O3 content must be ≤0.2%, and the Na2O content must be ≤0.37%; the Si content of the metallic silicon powder must be ≥98%; the α-Al2O3 content of the α-Al2O3 fine powder must be ≥98%, with a particle size of ≤1 micron; and the Al content of the metallic aluminum powder must be ≥99%. The binder used in preparing the corundum cast steel head is clay.

[0103] S22. Prepare co-ground powder: Premix 0-0.5 mm plate-shaped corundum powder, metallic silicon powder, metallic aluminum powder, and α-Al2O3 micropowder and co-grind in a ball mill for 33 minutes to form the co-ground powder. Hang five magnets below the ball mill and clean the iron filings from the magnets after each abrasive is discharged.

[0104] S23. Prepare the slurry: Mix 2-6 mm plate-shaped corundum aggregate and 0.5-2 mm plate-shaped corundum aggregate for 3-5 minutes until uniform. Then, add the co-ground powder prepared in step S22, water, and a binder. Mix and stir uniformly in a wet mill to obtain the wet material for the corundum-cast steel head. Hang at least five magnets under the wet mill. Clean the iron filings from the magnets after each milling.

[0105] S24, molding: put the embryo wet material into the mold, place it in the upper type vibration pressure molding machine, and vibrate, pressurize and ram to form it.

[0106] S25, drying: after demoulding, the formed steel head blank is placed in an electric drying furnace, heated from room temperature to 133°C for 1 hour, and kept at 130°C for 12 hours to dry the moisture of the steel head blank.

[0107] S26, sintering: put the dried steel head blank into the nitriding furnace for sintering, heating from room temperature to 1530℃, heating time 11 hours, then sintering at 1520℃ for 13 hours, nitrogen flow rate 12m 3 / h; after sintering, take it out and cool it to obtain the corundum cast steel head 2.

[0108] S3. Finally, the prepared graphite flow channel trough 1 and the corundum casting steel head 2 are spliced ​​together to obtain a split nanocrystalline alloy casting steel trough.

[0109] The graphite flow channel grooves and corundum casting steel heads prepared in Preparation Examples 1 to 3 were subjected to performance tests, and the data are shown in Tables 1 and 2 below.

[0110] Table 1 Properties of graphite flow channel grooves prepared in Preparation Examples 1 to 3

[0111]

[0112] Table 2 Properties of the corundum cast steel heads obtained in Preparation Examples 1 to 3

[0113]

[0114] The above embodiments are merely illustrative of the concepts and technical solutions of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical concepts disclosed herein are intended to be covered by the claims of the present invention.

[0115] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each implementation method can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A method for preparing a split nanocrystalline alloy casting trough, characterized in that: The split nanocrystalline alloy casting trough is formed by splicing a graphite runner trough at the rear section and a corundum casting head at the front section. The graphite runner trough is made of graphite, and the corundum casting head is made of plate-shaped corundum. The graphite runner trough and the corundum casting head are detachably connected by an overlap structure. The preparation method of the split nanocrystalline alloy casting trough comprises the following steps: S1. Preparation of graphite flow channel: S11, crushing, screening and batching: first, the raw materials for preparing the graphite flow channel groove are crushed and screened into 1# material with a particle size of 5 mesh, 2# material with a particle size of 20 mesh, 3# material with a particle size of 100 mesh, 4# material with a particle size of 200 mesh and 5# material with a particle size of 300 mesh; then, the crushed materials of different particle sizes are uniformly mixed according to the weight ratio of 1# material: 2# material: 3# material: 4# material: 5# material = (8-14): (12-18): (12-18): (12-18): (40-50) to obtain a first intermediate raw material; S12, dry mixing: dry mixing the prepared first intermediate raw materials, the dry mixing time is 30min~60min, and the dry mixing temperature is 60℃~80℃; S13, kneading: adding a binder and kneading at a kneading temperature of 80° C. to 95° C. for 50 min to 70 min to obtain a second intermediate raw material; S14, molding: drying the kneaded second intermediate raw material at a temperature of 90° C. to 115° C. for 25 to 40 minutes to obtain a clay material for isostatic pressing; then, the clay material is placed into a mold of a predetermined shape and pressed using an isostatic press at a molding pressure of 20 MPa to 31 MPa and a holding time of 30 to 60 minutes to obtain an intermediate product; S15, curing and sintering: the intermediate product is placed in a tunnel kiln, filled with argon gas for protection and anti-oxidation roasting, the argon purity is ≥99%, the argon pressure is 0.55MPa~0.7MPa, the roasting temperature is 1000℃~1250℃, the roasting time is 48h~72h, and then naturally cooled to room temperature; S16, graphitization: the solidified and sintered product is then placed in a high-temperature graphitization furnace for graphitization treatment. The graphitization time is 60h~80h, and the maximum graphitization temperature is 2300℃~2600℃; S17, machining: machining the outer dimensions to obtain the graphite flow channel groove; S2. Preparation of corundum-cast steel head: S21. Weigh raw materials for preparing a corundum cast steel head. The corundum cast steel head is composed of the following raw materials by mass percentage: 30% to 43% of 2-6 mm plate-shaped corundum aggregate, 10% to 24% of 0.5-2 mm plate-shaped corundum aggregate, 20% to 32% of 0-0.5 mm plate-shaped corundum powder, 5% to 10% of metallic silicon powder, 2% to 4% of metallic aluminum powder, 5% to 10% of α-Al2O3 fine powder, 4% to 7% of binder, and 3% to 6% of water. S22, preparing co-ground powder: premixing 0-0.5 mm plate-shaped corundum powder, metallic silicon powder, metallic aluminum powder and α-Al2O3 micropowder, and co-grinding for 30-40 minutes to form co-ground powder; S23, preparing the mud material: mixing 2-6 mm plate-shaped corundum aggregate and 0.5-2 mm plate-shaped corundum aggregate for 3-5 min, then adding the co-ground powder obtained in step S22, adding water and a binder, and mixing and stirring uniformly to obtain a wet material for the corundum casting steel head; S24, molding: The embryo wet material is placed into a mold, and placed in an overhead vibration pressure molding machine for vibration, pressure, and ramming to form the embryo; S25, drying: after demoulding, drying the formed steel head blank at a temperature of 120° C. to 135° C., heating time of 1 hour, and keeping the temperature at 120° C. to 135° C. for 9 hours to 12 hours; S26, sintering: put the dried steel head blank into the nitriding furnace for sintering. The nitriding sintering temperature is 1400℃~1550℃, the heating time is 11 hours, and the temperature is kept at 1400℃~1550℃ for 11h~13h. The nitrogen flow rate is 11m 3 / h~12m 3 / h; after sintering, take it out and cool it to obtain the corundum cast steel head; S3. Splice the graphite runner trough and the corundum casting steel head to obtain a split nanocrystalline alloy casting steel trough.

2. The method for preparing a split nanocrystalline alloy casting trough according to claim 1, characterized in that: The graphite flow channel groove includes a horizontally distributed groove bottom, and both sides of the groove bottom and the side away from the corundum casting head are provided with groove walls extending upward, and the end of the groove bottom away from the corundum casting head is provided with a downward opening discharge pipe; the corundum casting head includes a casting head body, and the upper surface of the casting head body has a guide arc surface distributed upward away from the graphite flow channel groove, and both sides of the casting head body are respectively provided with upward extending ribs.

3. The method for preparing a split nanocrystalline alloy casting trough according to claim 2, characterized in that: The central axis of the discharge pipe is perpendicular to the bottom of the trough. The discharge pipe is in the shape of a cone with a larger upper portion and a smaller lower portion, and a taper of (1:10) to (1:20).

4. The method for preparing a split nanocrystalline alloy casting trough according to claim 2, wherein: There are arc transitions between the groove wall and the groove bottom, and between the retaining edge and the casting head body.

5. The method for preparing a split nanocrystalline alloy casting trough according to claim 2, characterized in that: The curvature of the guide cambered surface is R500mm~R1000mm.

6. The method for preparing a split nanocrystalline alloy casting trough according to claim 1, characterized in that: The overlapping structure includes an upper overlapping joint and a lower overlapping joint which are seamlessly overlapped.

7. The method for preparing a split nanocrystalline alloy casting trough according to claim 6, characterized in that: The upper lap joint and the lower lap joint are both distributed along the width direction of the split nanocrystalline alloy casting steel trough.

8. The method for preparing a split nanocrystalline alloy casting trough according to claim 1, characterized in that: In step S11, the raw material used to prepare the graphite flow channel groove is an ungraphitized carbon material with a carbon content of ≥99%, ash content ≤0.35%, volatile matter ≤0.4%, and sulfur content ≤0.16%; in step S21, the index requirements of the raw material used to prepare the corundum casting steel head are as follows: the Al2O3 content in the plate-shaped corundum aggregate is ≥99%, the Fe2O3 content is ≤0.2%, and the Na2O content is ≤0.37%; the Si content in the metallic silicon powder is ≥98%; the α-Al2O3 content in the α-Al2O3 micropowder is ≥98%, and the particle size is ≤1 micron; the Al content in the metallic aluminum powder is ≥99%.

9. The method for preparing a split nanocrystalline alloy casting trough according to claim 1, characterized in that: In step S13, the binder used to prepare the graphite flow channel groove is any one of polyurethane resin, silicone resin, and polyimide, and the amount of the binder accounts for 6% to 13% of the total amount of the first intermediate raw material; in step S21, the binder used to prepare the corundum cast steel head is any one of polyvinyl alcohol, ethylene-vinyl alcohol copolymer, and clay.

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