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CN-122010564-A - Process for preparing heating element based on powder injection molding method

CN122010564ACN 122010564 ACN122010564 ACN 122010564ACN-122010564-A

Abstract

The invention belongs to the technical field of heating elements, and particularly relates to a process for preparing a heating element based on a powder injection molding method. The method comprises the steps of mixing metal oxide powder with a dispersing agent, drying to obtain premixed powder, mixing the premixed powder with a binder, granulating to obtain injection particles, carrying out injection molding on the injection particles to obtain an injection molding blank, degreasing and sintering the injection molding blank to obtain a heating body, wherein the raw materials of the metal oxide powder comprise lanthanum oxide, strontium carbonate and manganese oxide, the raw materials of the binder comprise paraffin, high-density polyethylene, stearic acid, hydrogenated rosin glyceride, polycaprolactone, acetyl tributyl citrate, sorbitan monooleate and an antioxidant, and the dispersing agent comprises oleic acid and/or sorbitan monooleate. The heating element prepared by the invention has the advantages of high heating rate and good thermal shock resistance.

Inventors

  • SUN XIN
  • XIE ZHENTING
  • XIE SONG
  • RAN SHEN
  • LIU YUN
  • Zhuo Shaohua

Assignees

  • 合肥汇智新材料科技有限公司

Dates

Publication Date
20260512
Application Date
20260416

Claims (10)

  1. 1. The process for preparing the heating element based on the powder injection molding method is characterized by comprising the following steps of: Mixing metal oxide powder with dispersant, drying to obtain premixed powder, mixing the premixed powder with binder, granulating to obtain injection particles, injection molding the injection particles to obtain injection molded blank, degreasing the injection molded blank, and sintering to obtain heating element; Wherein, the raw materials of the metal oxide powder comprise lanthanum oxide, strontium carbonate and manganese oxide; the raw materials of the adhesive comprise paraffin, high-density polyethylene, stearic acid, hydrogenated rosin glyceride, polycaprolactone, acetyl tributyl citrate, sorbitan monooleate and antioxidant; the dispersant comprises oleic acid and/or sorbitan monooleate.
  2. 2. The process for producing a heat-generating body based on a powder injection molding method according to claim 1, characterized in that the production method of the metal oxide powder comprises the steps of: Weighing lanthanum oxide, strontium carbonate and manganese oxide, enabling the mass ratio of La, sr and Mn to be 0.7:0.3:1, ball milling, mixing, drying, preserving heat at 900-1100 ℃ for 3-5 hours under the air atmosphere, cooling to room temperature along with a furnace, ball milling the pre-sintered massive materials again, and sieving to obtain the metal oxide powder with the average particle size D50 of 2-3 mu m.
  3. 3. The process for producing a heat-generating body based on a powder injection molding method according to claim 1, wherein the metal oxide powder and the dispersant are mixed and dried to obtain a premixed powder, comprising the steps of: Adding metal oxide powder and a dispersing agent into a ball mill, taking absolute ethyl alcohol as a medium, adding zirconia balls, ball-milling and mixing for 2-4 hours at the rotating speed of 200-300r/min, then placing into a rotary evaporator, evaporating ethanol under reduced pressure at 49-60 ℃, and then placing the obtained powder into a vacuum drying box at 70-90 ℃ for drying for 1-3 hours to obtain premixed powder.
  4. 4. The process for preparing a heating element based on a powder injection molding method according to claim 1, wherein the mass of the dispersing agent is 0.5% -1% of that of the metal oxide powder, and the premixed powder and the binder are mixed according to a mass ratio of 1-6:1.
  5. 5. The process for preparing a heating element based on a powder injection molding method according to claim 1, wherein the preparation method of the binder comprises the steps of: Weighing paraffin, high-density polyethylene and stearic acid, adding into a stirrer, setting the temperature to 120-140 ℃, starting heating, simultaneously starting stirring at the rotating speed of 20-40r/min, heating for 20-40 min, increasing the rotating speed to 50-70r/min, continuing stirring for 30-50 min, cooling and solidifying after stirring is completed, and crushing into particles with the size of 5-10mm to obtain the adhesive.
  6. 6. The process for preparing a heating element based on a powder injection molding method according to claim 1, wherein the preparation method of the binder comprises the steps of: Adding hydrogenated rosin glyceride into a stirrer, heating to 80-120 ℃, starting stirring at the rotating speed of 40-60r/min, adding polycaprolactone after the hydrogenated rosin glyceride is completely melted, heating to 100-140 ℃, sequentially adding acetyl tributyl citrate, sorbitan monooleate and an antioxidant, heating to 120-150 ℃, maintaining the temperature, increasing the rotating speed to 60-100r/min, continuously stirring for 40-80 min, and after stirring, performing vacuum defoaming, cooling and solidifying, and crushing into 5-10mm particles to obtain the adhesive.
  7. 7. The process for producing a heat-generating body based on a powder injection molding method according to claim 1, wherein the pre-mixed powder is kneaded with a binder and granulated to obtain injection particles, comprising the steps of: Adding the premixed powder and the binder into a double-screw mixer, setting the mixing temperature to be 80-160 ℃, mixing the powder and the binder at the screw speed of 40-80r/min, granulating the mixed injection feed by a single-screw granulator, controlling the granulating temperature to be 80-160 ℃, controlling the screw speed to be 30-60r/min and controlling the particle size range to be 0.5-2mm.
  8. 8. The process for producing a heat-generating body based on a powder injection molding method according to claim 1, wherein injection-molding the injection-molded particles to obtain an injection-molded green body comprises the steps of: Adding injection particles into a charging barrel of an injection molding machine, setting the temperature of the charging barrel to be 80-160 ℃, setting the injection pressure to be 70-120MPa, setting the injection speed to be 30-50cm 3 /s, setting the holding pressure to be 50-100MPa, setting the holding time to be 10-20s, starting the injection molding machine, injecting molten injection feed into a mold cavity, opening the mold after the blank is cooled and solidified, taking out the molded blank, and maintaining the ambient temperature to be 20-30 ℃ and the relative humidity to be 40-50% in the injection molding process to obtain the injection molded blank.
  9. 9. A process for producing a heat-generating body based on a powder injection molding method according to claim 5, wherein, Degreasing and sintering the injection molding blank to obtain a heating body, which comprises the following steps: Soaking the injection molding blank in normal hexane for 4-6 hours, taking out the blank after degreasing by the solvent, sucking the solvent, placing the blank after degreasing by the solvent into a high-temperature furnace, heating from room temperature to 300-500 ℃ at a heating rate of 1-2 ℃ per minute, preserving heat for 2-3 hours, and naturally cooling to room temperature along with the furnace after degreasing is finished; Placing the degreased blank body into a high-temperature sintering furnace, heating from room temperature to 800-900 ℃ at a heating rate of 3-5 ℃ per minute, preserving heat for 2-3 hours, continuously heating to 1200-1300 ℃ at the heating rate of 3-5 ℃ per minute, preserving heat for 4-6 hours, slowly cooling to room temperature along with the furnace after sintering, and controlling the cooling rate to 2-10 ℃ per minute to obtain the heating body.
  10. 10. The process for producing a heat-generating body based on a powder injection molding method according to claim 6, wherein the injection molded green body is degreased and sintered to obtain the heat-generating body, comprising the steps of: Placing the injection molding blank into a high-temperature furnace, heating from room temperature to 100-200 ℃ at a heating rate of 0.5-2 ℃ per minute, preserving heat for 1-2 hours, heating to 300-500 ℃ at a heating rate of 1-2 ℃ per minute, preserving heat for 2-3 hours, and naturally cooling to room temperature along with the furnace after degreasing is finished; Placing the degreased blank body into a high-temperature sintering furnace, heating from room temperature to 800-900 ℃ at a heating rate of 3-5 ℃ per minute, preserving heat for 2-3 hours, continuously heating to 1200-1300 ℃ at the heating rate of 3-5 ℃ per minute, preserving heat for 4-6 hours, slowly cooling to room temperature along with the furnace after sintering, and controlling the cooling rate to 2-10 ℃ per minute to obtain the heating body.

Description

Process for preparing heating element based on powder injection molding method Technical Field The invention belongs to the technical field of heating elements, and particularly relates to a process for preparing a heating element based on a powder injection molding method. Background The heating element in the current market mainly comprises two major types of metal heating wires (such as nickel-chromium alloy and iron-chromium-aluminum alloy) and ceramic heating elements. The traditional metal heating wire has the problems of easy oxidation at high temperature, short service life, poor temperature control precision, dry burning risk, possible release of heavy metal ions and potential safety hazard. The existing ceramic heating body mostly adopts an alumina matrix to load a metal conductive phase or adopts a PTC (positive temperature coefficient) ceramic material, but has the defects of lower heating rate, influence on the instant use experience of users, limited thermal shock resistance and easy cracking due to frequent cold and hot circulation. Disclosure of Invention The invention aims to provide a process for preparing a heating element based on a powder injection molding method. The above object of the present invention is achieved by the following technical solutions: the process for preparing the heating element based on the powder injection molding method comprises the following steps: Mixing metal oxide powder with dispersant, drying to obtain premixed powder, mixing the premixed powder with binder, granulating to obtain injection particles, injection molding the injection particles to obtain injection molded blank, degreasing the injection molded blank, and sintering to obtain heating element; The raw materials of the metal oxide powder comprise lanthanum oxide, strontium carbonate and manganese oxide, the raw materials of the binder comprise paraffin, high-density polyethylene, stearic acid, hydrogenated rosin glyceride, polycaprolactone, acetyl tributyl citrate, sorbitan monooleate and antioxidant, and the dispersing agent comprises oleic acid and/or sorbitan monooleate. Further, the preparation method of the metal oxide powder comprises the following steps: Weighing lanthanum oxide, strontium carbonate and manganese oxide, enabling the mass ratio of La, sr and Mn to be 0.7:0.3:1, ball milling, mixing, drying, preserving heat at 900-1100 ℃ for 3-5 hours under the air atmosphere, cooling to room temperature along with a furnace, ball milling the pre-sintered massive materials again, and sieving to obtain the metal oxide powder with the average particle size D50 of 2-3 mu m. Further, the metal oxide powder and the dispersant are mixed and dried to obtain a premixed powder, comprising the steps of: Adding metal oxide powder and a dispersing agent into a ball mill, taking absolute ethyl alcohol as a medium, adding zirconia balls, ball-milling and mixing for 2-4 hours at the rotating speed of 200-300r/min, then placing into a rotary evaporator, evaporating ethanol under reduced pressure at 49-60 ℃, and then placing the obtained powder into a vacuum drying oven at 70-90 ℃ for drying for 1-3 hours to obtain premixed powder. Further, the mass of the dispersing agent is 0.5% -1% of that of the metal oxide powder, and the premixed powder and the binder are mixed according to the mass ratio of 1-6:1. Further, the preparation method of the adhesive comprises the following steps: Weighing paraffin, high-density polyethylene and stearic acid, adding into a stirrer, setting the temperature to 120-140 ℃, starting heating, simultaneously starting stirring at the rotating speed of 20-40r/min, heating for 20-40 min, increasing the rotating speed to 50-70r/min, continuing stirring for 30-50 min, cooling and solidifying after stirring is completed, and crushing into particles with the size of 5-10mm to obtain the adhesive. It should be noted that High Density Polyethylene (HDPE) has the advantages of strong entanglement of HDPE chains, formation of a denser polymer network, stronger mechanical support provided by HDPE crystalline regions, small density difference between HDPE and LSMO powder, reduced sedimentation separation, and stronger ability of HDPE to retain the shape of the green body at the initial stage of degreasing. In the subsequent mixing process, the HDPE molecular chain, paraffin wax and stearic acid form an interpenetrating network structure. Paraffin wax is used as a main lubricating and filling component, stearic acid is used as a surfactant to improve the interfacial bonding of the powder and a binder, and HDPE is used as a skeleton polymer, so that the high crystallinity and the strong chain entanglement capability of the skeleton polymer ensure that the HDPE network is uniformly dispersed in a paraffin wax matrix in the mixing stage, and the LSMO powder is anchored at a polymer network node to prevent powder sedimentation and agglomeration. 2. The high melt strength of HDPE during the molding s