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A method and product thereof for preparing fine-grained barium titanate heat-sensitive ceramics

A technology of crystalline barium titanate and heat-sensitive ceramics, which is applied in the field of low-temperature sintering to prepare fine-crystalline barium titanate-based heat-sensitive ceramics, can solve the problems of difficulty in improving the electrical properties of chip thermistors, complicated processes and high sintering temperature, and achieves It is easy to popularize and apply on a large scale, the method is simple and easy to implement, and the effect of reducing the sintering temperature

Active Publication Date: 2019-04-12
HUAZHONG UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Too high sintering temperature and too large grains are not suitable for the preparation of laminated chip thermistors
Moreover, barium titanate semiconductor ceramics need to use base metal (such as nickel) electrodes to form ohmic contacts. Since the oxidation temperature of base metals is relatively low, it needs to be prepared by reduction and re-oxidation process, which is complicated.
[0005] In addition, under the current thermistor production process, the average grain size of barium titanate-based thermosensitive ceramics is about 1 micron, and the minimum thickness of a single-layer ceramic layer can only be 30 microns
It has the following problems: the ceramic grain size is still too large, and the density is difficult to precisely control, which makes it difficult to improve the electrical properties of the chip thermistor, the withstand voltage is difficult to improve, especially its room temperature resistance is difficult to further reduce, which greatly limits the use of titanic acid. Wide application of barium-based thermosensitive ceramics

Method used

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  • A method and product thereof for preparing fine-grained barium titanate heat-sensitive ceramics
  • A method and product thereof for preparing fine-grained barium titanate heat-sensitive ceramics

Examples

Experimental program
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Effect test

Embodiment 1

[0032] S1: Mix nano-barium titanate heat-sensitive powder, donor powder, acceptor powder and sintering aid BN to prepare raw material powder. Specifically, 0.5 mol of BaTiO with a particle size of 100 nm 3 Hydrothermal powder, 0.002mol La 2 o 3 The donor powder, 0.001mol Mn acceptor powder and 0.04mol BN sintering aid were mixed to obtain a mixture. Among them, BaTiO 3 , donor powder and BN are added in the form of solid phase, and the acceptor powder is added in the form of Mn(NO 3 ) 2 Added in the form of aqueous solution, the mass fraction of manganese nitrate is 1%. Mix the above mixture with deionized water, ball mill, dry, and sieve, and take 100 g for later use.

[0033] S2: Weigh 25g of absolute ethanol, 25g of toluene, 0.3g of dispersant, and 0.3g of defoamer, mix it with the above powder and mill it for 12 hours, then add 40g of binder, and ball mill the resulting slurry, then ball mill it for 12 hours. Casting slurry. The casting slurry was cast into a green...

Embodiment 2

[0038] This example is the same as Example 1, except that in step S3, the time for keeping warm at 940° C. is 2 hours, and the others are the same.

[0039] The microstructure and properties of the fine-grained barium titanate heat-sensitive ceramics prepared in this example are as follows: the average grain size is 318nm, the density is 83%, the room temperature resistivity of the obtained ceramic piece is 1500Ω·cm, and the lift-to-drag ratio R 250 / R 25 =8.9×10 3 .

Embodiment 3

[0041] The difference between this example and Example 1 is that in step S3, the time for keeping warm at 940° C. is 6 hours, and the others are the same.

[0042] The microstructure and properties of the fine-grained barium titanate heat-sensitive ceramics prepared in this example are as follows: the average grain size is 325nm, the density is 89%, the room temperature resistivity of the obtained ceramic piece is 288Ω·cm, and the lift-to-drag ratio R 250 / R 25 =8.9×10 3 .

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Abstract

The invention discloses a method for preparing fine-grained barium titanate temperature-sensitive ceramic and a product thereof, and belongs to the field of electronic ceramic elements. The method comprises the following steps: S1, nanometer barium titanate temperature-sensitive powder, donor powder, acceptor powder and a sintering agent BN are mixed, and the grain diameter of nanometer barium titanate temperature-sensitive powder is 20-500 nm; S2, the raw material powder is prepared into a chip type laminated green compact and glue is discharged, and a blank to be sintered is obtained; S3, the blank to be sintered is sintered, insulation is carried out at 950-1100 DEG C for 5-30 minutes, the temperature is adjusted to 900-1000 DEG C and insulation is carried out for 30 minutes to 12 hours, and barium titanate moulded ceramic is obtained; S4, in the temperature range from 600 to 850 DEG C, and the barium titanate moulded ceramic is reoxidized. The average crystal grain of barium titanate fine-grained temperature-sensitive ceramic is regulated within 120-800nm, the density is regulated within 80-95%, the room temperature resistivity is low, and the ratio of lg (Rmax / Rmin) is high.

Description

technical field [0001] The invention belongs to the technical field of preparation of electronic ceramic components, and in particular relates to a method for preparing fine-crystalline barium titanate-based heat-sensitive ceramics by low-temperature sintering and a product thereof. Background technique [0002] In electronic circuits and electronic machines, barium titanate-based positive temperature coefficient ceramic thermistors are used for overheating and overcurrent protection of IC devices, lithium batteries, switching power supplies, and automotive motors. They are widely used in mobile communications, high-definition Color TV, local area network, computer, automotive electronics and other fields. With the rapid development of electronic circuits and electrical appliances towards miniaturization, integration and multi-function, it is required that the conventional protection element thermistor should also be miniaturized. At the same time, in order to meet the requ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01C7/02
Inventor 傅邱云周东祥郑志平胡云香罗为高超
Owner HUAZHONG UNIV OF SCI & TECH
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