CN-118184324-B - Liquid lifting tube for high-melting-point alloy antigravity casting and preparation method thereof

CN118184324BCN 118184324 BCN118184324 BCN 118184324BCN-118184324-B

Abstract

The invention discloses a lift tube for high-melting-point alloy antigravity casting and a preparation method thereof, and the lift tube is structurally characterized in that a silica-based ceramic matrix is internally embedded with a quartz glass tube, and the inner surface and the outer surface of the lift tube are coated with protective coatings; the manufacturing process is that a quartz glass tube is preset in a mould, a silica-based ceramic matrix is formed by hot pressing injection, the inner layer and the outer layer are protective coatings formed by brushing alumina powder and zircon powder slurry, and the protective coatings are delivered for use after sintering. The liquid lifting tube has the advantages of high temperature resistance, good chemical stability and air tightness, low manufacturing cost and the like, can be used for high-temperature alloy antigravity casting, and is also suitable for antigravity casting of metal materials such as cast steel, cast iron and the like.

Inventors

MA LANBO
LIU XIAOFU
GUO XINLI
SUN XUN
SU GUIQIAO
JIN LEI
SHUI GUOYAN
GUAN YANG

Assignees

沈阳铸造研究所有限公司

Dates

Publication Date: 20260512
Application Date: 20221214

Claims (5)

1. A lift tube for antigravity casting of high-melting-point alloy is characterized in that: The liquid lifting tube comprises a protective coating (1), a silicon oxide-based ceramic matrix (2) and a quartz glass tube (3); wherein the quartz glass tube (3) is embedded in the silica-based ceramic matrix (2), and the inner surface and the outer surface of the silica-based ceramic matrix (2) are provided with protective coatings (1); the preparation method comprises the steps of mixing the base material and the mineralizer, adding oleic acid accounting for 0.1-0.5% of the weight of powder, ball milling by adding alumina ceramic balls according to a ball ratio of 2:1 to obtain mixed powder, heating and melting a plasticizer accounting for 15-20% of the weight of the mixed powder at 90-110 ℃, wherein the composition of the plasticizer is paraffin 90-95 wt%, beeswax 3-5 wt%, polyethylene glycol 1-3 wt%, and a pre-heating and mixing tube accounting for 6-2 wt% of the mixed powder to obtain a mixed powder, preheating the mixed powder in a quartz glass mold, and then the core material is manufactured into a biscuit through hot pressing injection molding, the inner and outer surfaces of the silicon oxide-based ceramic matrix (2) are coated with the protective coating (1) by adopting a brushing method, wherein the protective coating (1) comprises 50-60wt% of high-purity alumina powder, 5-25wt% of zircon powder and 25-35wt% of silica sol.
2. The lift tube for high-melting-point alloy antigravity casting according to claim 1, wherein the base material and the mineralizer comprise, by weight, 75-95% of quartz glass powder, 4-20% of zircon powder and 1-5% of analytically pure aluminum oxide powder, wherein in the quartz glass powder, powder with 200 meshes accounts for 8-12%, powder with 325 meshes accounts for 59-71% and powder with 500 meshes accounts for 8-12%.
3. The lift tube for antigravity casting of high-melting-point alloy according to claim 1, wherein the high-temperature strengthening liquid of the silicon oxide-based ceramic matrix (2) is silica sol, the soaking time is 0.5h, natural air drying is carried out for 4-6 h, and the drying is carried out for 1-3 h at 110-150 ℃ for 1-3 times of strengthening.
4. A method for preparing a lift tube for antigravity casting of a high melting point alloy according to any one of claims 1 to 3, which is characterized by comprising the following specific process steps: 1) The quartz glass tube is perforated, wherein the tube wall of the quartz glass tube is perforated by laser, the holes are uniformly distributed, the axial distance is not less than 30mm, the radial distribution number is not less than 2, and the aperture is not less than 5mm; 2) Firstly, respectively weighing quartz glass powder, zircon powder and analytically pure aluminum oxide powder with a certain weight, putting the quartz glass powder, the zircon powder and the analytically pure aluminum oxide powder into a ball milling tank, adding oleic acid accounting for 0.1-0.5% of the weight of the powder, adding aluminum oxide ceramic balls according to a ball-to-material ratio of 2:1, mixing for 4-10 hours to obtain mixed powder, then putting a plasticizer accounting for 15-20% of the weight of the mixed powder into a core mixer, heating and melting the plasticizer at 90-110 ℃, wherein the plasticizer comprises 90-95 wt.% of paraffin wax, 3-5 wt.% of beeswax, 1-3 wt.% of polyethylene and 1-2 wt.% of polyethylene glycol, and finally, adding the uniformly mixed powder into the core mixer, and continuously stirring for 6-10 hours to uniformly mix the plasticizer and the mixed powder; 3) Presetting a quartz glass tube, namely preheating the quartz glass tube to 35-45 ℃, and presetting the quartz glass tube in a lift tube silica-based ceramic matrix mold; 4) Hot pressing and molding, namely, utilizing a ceramic hot pressing and molding machine to press and mold the uniformly mixed core material into a lift tube silica-based ceramic matrix mold to prepare a lift tube silica-based ceramic matrix biscuit; 5) Trimming and shaping, namely trimming and shaping a liquid lifting tube silica-based ceramic matrix biscuit, placing the biscuit into a sagger, burying the biscuit with industrial alumina filler, calcining the industrial alumina filler at 1450 ℃ for 8-12 hours in advance, and sieving the calcined alumina filler with a 250-mesh sieve; 6) Roasting, namely placing a sagger filled with a liquid lifting tube silica-based ceramic matrix biscuit and industrial alumina filler into a box-type resistance furnace for roasting, and then cooling to room temperature along with the furnace; 7) High temperature strengthening, namely strengthening a lift tube silica-based ceramic matrix by taking silica sol as strengthening liquid, wherein the strengthening time is 1-3 times, soaking for 0.5h each time, naturally air-drying for 4-6h, and drying for 1-3 h at 110-150 ℃, and then carrying out the next strengthening; 8) The preparation of the coating comprises the steps of uniformly stirring 50-60wt% of 100-400 mesh high-purity aluminum oxide powder, 5-25wt% of 100-400 mesh zircon powder, 25-35wt% of silica sol for at least 12 hours to prepare the coating, and coating the inner and outer surfaces of a silicon oxide ceramic matrix with a 0.5-1.5 mm thick coating by a brushing method; 9) The coating is baked, wherein a brushing method is adopted to prepare the coating, the coating is naturally dried for 8-12 hours and is used after baking, the baking system is that the temperature is raised to 400-500 ℃ at a temperature rise rate of 2-4 ℃ per minute, the temperature is kept for 1-2 hours, the temperature is raised to 900-1100 ℃ at a temperature rise rate of 3-5 ℃ per minute, and the baking system is used after the baking system is kept for 4-8 hours.
5. The method for preparing the riser tube for the antigravity casting of the high-melting-point alloy, which is characterized in that in the step 4), the hot-press injection molding process parameters comprise 95-105 ℃ of injection temperature, 35-45 ℃ of mold temperature, 2-6 MPa of injection pressure, 100-300 cc/s of flow, 20-30 s of injection time and 100-200 s of dwell time; In the step 6), the roasting system is that the temperature is raised to 400-500 ℃ at the temperature raising rate of 2-6 ℃ per minute, the temperature is kept for 4-6 hours, the temperature is raised to 700-900 ℃ at the temperature raising rate of 3-7 ℃ per minute, the temperature is kept for 2-4 hours, the temperature is raised to 1100-1200 ℃ at the temperature raising rate of 4-8 ℃ per minute, the temperature is kept for 8-12 hours, and the temperature is cooled to room temperature along with a furnace.

Description

Liquid lifting tube for high-melting-point alloy antigravity casting and preparation method thereof Technical Field The invention relates to the technical field of antigravity casting, and particularly provides a liquid lifting tube for antigravity casting of high-melting-point alloys such as high-temperature alloys, cast steel and cast iron and a preparation method thereof. Background The antigravity casting, including low pressure casting, vacuum suction casting, pressure regulating casting, differential pressure casting, etc. is a casting technology for filling casting mould from bottom to top along liquid lifting pipe under the drive of electromagnetic force or gas pressure. The application of the domestic antigravity casting technology in the fields of low-melting-point light metals such as aluminum alloy, magnesium alloy and the like is developed to be mature, but the application in the fields of higher-melting-point alloys such as cast iron, cast steel, high-temperature alloy and the like is still in an exploration stage. The liquid lifting pipe plays a role of a flow guiding and feeding channel when a casting is formed, is a key part of antigravity casting equipment, and has higher requirements on air tightness, high-temperature chemical stability, high-temperature strength and thermal shock resistance. The refractory material has better chemical stability and certain high-temperature strength, but the single refractory material cannot simultaneously have thermal shock resistance and air tightness. Therefore, many of the riser tubes for antigravity casting used in the fields of cast steel, cast iron, high-temperature alloy and the like are of composite structures. The patent CN1039984A discloses an integrally-poured composite lift tube which takes a steel tube as a framework, internally and externally pours high-alumina bauxite refractory materials, is suitable for ferrous metals such as cast iron, cast steel and the like, and the patent CN109940152A discloses an antigravity casting lift tube for high-temperature alloy and a manufacturing method thereof. The silicon oxide-based ceramic formed by hot pressing injection molding is widely applied as a ceramic core in the investment casting process of high-melting-point alloy such as cast steel, cast iron, high-temperature alloy and the like, does not react with various alloy elements, shows good chemical stability, has certain apparent porosity and also shows good thermal shock resistance, but has the problems that the air tightness cannot meet the use requirement when being used as a liquid lift tube for high-melting-point alloy counter-gravity casting, and the like. Disclosure of Invention The invention overcomes the defect of insufficient air tightness of hot-pressed injection molding ceramics, and provides a liquid lifting tube for antigravity casting of high-melting-point alloys such as cast steel, cast iron, high-temperature alloy and the like and a preparation method thereof. The liquid lifting pipe has the advantages of high temperature resistance, no pollution to high-temperature alloy metal liquid, good thermal shock resistance and the like, and has lower manufacturing cost. The technical scheme of the invention is as follows: As shown in fig. 1, a lift tube for antigravity casting of a high melting point alloy is characterized in that: the liquid lifting tube comprises a protective coating, a silica-based ceramic matrix and a quartz glass tube, wherein the quartz glass tube is embedded in the silica-based ceramic matrix, and the inner surface and the outer surface of the silica-based ceramic matrix are provided with the protective coating. The thickness of the flange plate of the silicon oxide ceramic matrix is more than 8mm, and the wall thickness of the pipe wall part is more than 6mm. The quartz glass tube has good air tightness and has a thermal expansion coefficient close to that of the silicon oxide-based ceramic matrix. The round wall of the quartz glass tube is provided with holes, so that the forming capability and the structural strength of the silicon oxide-based ceramic matrix of the lift tube are improved while the air tightness of the lift tube is not obviously affected. According to the invention, a quartz glass tube is preset in a die for one-step molding during hot-press injection molding of a silica-based ceramic matrix to obtain better air tightness, and a protective coating with the thickness of 0.5-1.5 mm is coated on the inner surface and the outer surface of the silica-based ceramic matrix by a brushing method, so that the chemical stability of a lift tube can be improved, wherein the protective coating comprises 50-60 wt.% of high-purity alumina powder (the purity is more than or equal to 99.9%), 5-25 wt.% of zircon powder and 25-35 wt.% of silica sol. As a preferable technical scheme: The wall of the quartz glass tube is perforated by laser, the aperture is not less than 5mm, the holes are uniformly distributed, the