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CN-121990822-A - Full-series lead-free barium titanate thermistor with Curie point of 60-125 ℃ and preparation method thereof

CN121990822ACN 121990822 ACN121990822 ACN 121990822ACN-121990822-A

Abstract

The invention relates to the technical field of electronic ceramic component preparation, in particular to a full-series lead-free barium titanate thermistor with a Curie point of 60-125 ℃ and a preparation method thereof, wherein the full-series lead-free barium titanate thermistor comprises, by mole, 0.99 part of fused block, 0.01 part of bismuth sodium titanate, 0.001-0.008 part of lithium carbonate, and the frit comprises, by mole, 0.669-0.868 part of barium carbonate, 0.10-0.181 part of calcium carbonate, 0.011-0.153 part of strontium carbonate, 0.0023-0.0032 part of yttrium oxide, 0.002-0.01 part of aluminum oxide, 0.0005-0.0012 part of manganese nitrate, 0.008-0.02 part of silicon dioxide and 0.992-1.3 part of titanium dioxide. BNT and strontium titanate are added at the A site, and lead titanate is replaced by BNT, so that the full-series leadless thermistor at 60-125 ℃ is realized.

Inventors

  • LIU HANG
  • YANG XINYU
  • ZHANG JUNGUO
  • LIU XIAOFENG

Assignees

  • 丹东国通电子元件有限公司

Dates

Publication Date
20260508
Application Date
20260409

Claims (9)

  1. 1. The full-series lead-free barium titanate thermistor with the Curie point of 60-125 ℃ is characterized by comprising, by mole, 0.99 part of fused mass, 0.01 part of bismuth sodium titanate and 0.001-0.008 part of lithium carbonate, wherein the ceramic material of the fused mass comprises, by mole, 0.669-0.868 part of barium carbonate, 0.10-0.181 part of calcium carbonate, 0.011-0.153 part of strontium carbonate, 0.0023-0.0032 part of yttrium oxide, 0.002-0.01 part of aluminum oxide, 0.0005-0.0012 part of manganese nitrate, 0.008-0.02 part of silicon dioxide and 0.992-1.3 part of titanium dioxide.
  2. 2. The full-series lead-free barium titanate-based thermistor with the curie point of 60 ℃ to 125 ℃ according to claim 1, wherein the PTC with the corresponding curie point temperature is obtained by dynamically adjusting the proportion of strontium carbonate, and specifically comprises: The molar part of strontium carbonate in the 60 ℃ Curie point PTC is 0.143-0.153 part; The molar part of strontium carbonate in the 70 ℃ Curie point PTC is 0.115-0.131 part; the molar part of strontium carbonate in the 80 ℃ Curie point PTC is 0.093-0.112 part; The molar part of strontium carbonate in the PTC at 90 ℃ is 0.078-0.088 part; the molar part of strontium carbonate in the 100 ℃ Curie point PTC is 0.0583-0.0653 part; The molar part of strontium carbonate in the 110 ℃ Curie point PTC is 0.035-0.047 part; The molar part of strontium carbonate in the 120 ℃ Curie point PTC is 0.019-0.025 part; the molar part of strontium carbonate in the 125 ℃ Curie point PTC is 0.011-0.016 part.
  3. 3. The full-series lead-free barium titanate-based thermistor according to claim 1 or 2, wherein the curie point is 60 ℃ to 125 ℃, the nominal resistance of the thermistor is 47 ohms, the lift-drag ratio is (1 to 3) ×10 6 , and the withstand voltage is 1000VDC.
  4. 4. A method for manufacturing the full-series lead-free barium titanate-based thermistor having a curie point of 60 ℃ to 125 ℃ as set forth in any one of claims 1 to 3, comprising the steps of: 1) Mixing raw materials of barium carbonate, calcium carbonate, strontium carbonate, yttrium oxide, aluminum oxide, manganese nitrate, silicon dioxide and titanium dioxide, presintering and synthesizing a smelting block; 2) Mixing the smelting block with bismuth sodium titanate and lithium carbonate to obtain a grinding ball; 3) Adding an adhesive and a release agent into the material obtained in the step 2), then carrying out spray granulation, and pressing the granules into blank sheets; 4) And sintering the blank sheet at high temperature under the air condition to obtain the PTC disc-shaped ceramic body, and manufacturing the PTC disc-shaped ceramic body into a resistor.
  5. 5. The method for manufacturing a full-series lead-free barium titanate thermistor with the curie point of 60 ℃ to 125 ℃ according to claim 4, wherein the step 1) is to perform pre-sintering after performing wet ball milling on the mixed material, wherein the ball milling granularity is 2.0 μm to 2.5 μm, the pre-sintering temperature is 1170 ℃ plus or minus 10 ℃, and the heat preservation is performed for 2 to 3 hours.
  6. 6. The method for manufacturing a full-series lead-free barium titanate-based thermistor having a curie point of 60 ℃ to 125 ℃ according to claim 4, wherein the particle size of the grinding balls in the step 2) is 1.8 μm to 2.3 μm.
  7. 7. The method for producing a full-range lead-free barium titanate-based thermistor having a curie point of 60 ℃ to 125 ℃ according to claim 4, wherein the particle size of the pellets in the step 3) is 124 μm to 250 μm.
  8. 8. The method for manufacturing the full-series lead-free barium titanate thermistor with the curie point of 60-125 ℃ according to claim 4, wherein the high-temperature sintering schedule in the step 4) is that the temperature is kept at room temperature to 600 ℃, the temperature rising rate is 250-300 ℃ per hour, the temperature is kept at 600 ℃ for 30 minutes, the temperature is kept at 600-1350 ℃, the temperature rising rate is 250-300 ℃ per hour, the temperature is kept at 1350 ℃ for 1-2 hours, the temperature is kept at 1350 ℃ -1200 ℃, the temperature is kept at 300-350 ℃ per hour, the temperature is kept at 1200 ℃ for 30-50 minutes, the temperature is kept at 1200 ℃ -850 ℃, the temperature is kept at 150-300 ℃ per hour, the temperature is kept at 850 ℃ or below, and the PTC round-plate ceramic body is obtained after the furnace is taken out.
  9. 9. The method for manufacturing a full-series lead-free barium titanate-based thermistor having a curie point of 60 ℃ to 125 ℃ according to claim 4, wherein the method for manufacturing bismuth sodium titanate is as follows: 1) The bismuth sodium titanate comprises the following components in mole ratio of bismuth oxide to sodium carbonate to titanium dioxide=1:1:4; 2) Mixing the materials according to the proportion, adding water, ball milling for 24+/-1 hours by a wet method, discharging, and drying in an oven at 120+/-1 ℃; 3) And a solid phase synthesis system, namely raising the temperature to 800-850 ℃ at the temperature raising rate of 250 ℃ per hour, and preserving the heat for 2-3 hours at a high temperature.

Description

Full-series lead-free barium titanate thermistor with Curie point of 60-125 ℃ and preparation method thereof Technical Field The invention relates to the technical field of electronic ceramic component preparation, in particular to a full-series lead-free barium titanate thermistor with Curie point of 60-125 ℃ and a preparation method thereof. Background The traditional barium titanate ceramic thermistor with Curie point of 60-125 ℃ is used for refining grains so as to improve the voltage resistance of PTC (positive temperature coefficient) ceramic, and besides the common A-site calcium doping for refining grains, the common A-site strontium lead co-addition is also used for refining grains so as to further improve the voltage resistance. Lead has irreversible pollution to the environment, and inhibition of lead use is a problem faced by human beings. Accordingly, it is a problem to be faced how to further refine the PTC ceramic grains and further improve the withstand voltage of the PTC thermistor without using lead. The invention attempts to replace lead titanate by bismuth sodium titanate (BNT) and compound doping of strontium titanate at A site to manufacture a full-series lead-free barium titanate thermistor with Curie point of 60-125 ℃. The performance of the PTC thermistor manufactured by the invention completely reaches or even exceeds the performance of the original strontium-lead co-added PTC thermistor. At present, the domestic 60-125 ℃ high-pressure PTC thermosensitive material mostly adopts a strontium-lead co-adding technology. The invention replaces lead titanate with BNT and carries out composite doping with strontium titanate at A site to manufacture the lead-free barium titanate series high voltage-resistant thermistor with the Curie point of 60-125 ℃ and fills a large blank for manufacturing the lead-free thermistor in China. Disclosure of Invention The invention adopts high calcium doping at the A position to obtain PTC thermistor ceramic material with low resistivity, fine grain and high withstand voltage, and simultaneously adds sodium bismuth titanate (BNT) and strontium titanate at the A position, and further refines grain and improves withstand voltage by compound doping at the A position. Lead-free series of thermistors at 60-125 ℃ is realized by replacing lead titanate by BNT. In order to achieve the above purpose, the invention adopts the following technical scheme: The full-series lead-free barium titanate thermistor with the Curie point of 60-125 ℃ is mainly applied to overheat protection circuits, overcurrent protection circuits and air conditioner starter starting circuits, and raw materials for preparing the thermistor comprise, by mole, 0.99 part of fused mass, 0.01 part of bismuth sodium titanate and 0.001-0.008 part of lithium carbonate, wherein the ceramic material of the fused mass comprises, by mole, 0.669-0.868 part of barium carbonate, 0.10-0.181 part of calcium carbonate, 0.011-0.153 part of strontium carbonate, 0.0023-0.0032 part of yttrium oxide, 0.002-0.01 part of aluminum oxide, 0.0005-0.0012 part of manganese nitrate, 0.008-0.02 part of silicon dioxide and 0.992-1.3 part of titanium dioxide. Further, the PTC with the corresponding Curie point temperature is obtained by dynamically adjusting the proportion of the strontium carbonate, and the PTC comprises the following specific components: The molar part of strontium carbonate in the 60 ℃ Curie point PTC is 0.143-0.153 part; The molar part of strontium carbonate in the 70 ℃ Curie point PTC is 0.115-0.131 part; the molar part of strontium carbonate in the 80 ℃ Curie point PTC is 0.093-0.112 part; The molar part of strontium carbonate in the PTC at 90 ℃ is 0.078-0.088 part; the molar part of strontium carbonate in the 100 ℃ Curie point PTC is 0.0583-0.0653 part; The molar part of strontium carbonate in the 110 ℃ Curie point PTC is 0.035-0.047 part; The molar part of strontium carbonate in the 120 ℃ Curie point PTC is 0.019-0.025 part; the molar part of strontium carbonate in the 125 ℃ Curie point PTC is 0.011-0.016 part. The nominal resistance of the thermistor is 47 ohms, the lift-drag ratio is (1-3) ×10 6, and the withstand voltage is 1000VDC. The invention relates to a manufacturing method of a full-series lead-free barium titanate thermistor with the Curie point of 60-125 ℃, which comprises the following steps: 1) Mixing raw materials of barium carbonate, calcium carbonate, strontium carbonate, yttrium oxide, aluminum oxide, manganese nitrate, silicon dioxide and titanium dioxide, presintering and synthesizing a smelting block; 2) Mixing the smelting block with bismuth sodium titanate and lithium carbonate to obtain a grinding ball; 3) Adding an adhesive and a release agent into the material obtained in the step 2), then carrying out spray granulation, and pressing the granules into blank sheets; 4) And sintering the blank sheet at high temperature under the air condition to obtain the PTC disc-shaped ceramic