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Method for forming water-base casting of sheet-type positive temperature coefficient thermal sensitive ceramic

A water-based tape casting, positive temperature coefficient technology, applied in the field of sheet ceramic materials, can solve the problems of poor flexibility of the ceramic green body, easy deformation and cracking of the green body, serious environmental pollution, etc., and achieves high production efficiency and fine grain size. Chemical and active effect

Inactive Publication Date: 2008-09-17
HUAZHONG UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The ceramic green body prepared by organic casting has uniform structure, high strength, good flexibility, and is easy to cut and process. However, due to the use of a large amount of toxic and flammable organic solvents (benzene, toluene, diethylbenzene, etc.) ), serious environmental pollution and high cost
In addition, due to the high content of organic matter in the slurry and the low density of the green body, the green body is easily deformed and cracked during the degreasing process
Therefore, in recent years, people have begun to study the water-based casting system using water as a solvent. This system can not only realize green production, but also has low cost. Water-based casting using water as a solvent to replace organic casting has become irreversible. Trend, Cui Xuemin and others reported the technical scheme of water-based casting ceramic green body in Silicate Bulletin 2004, 2, pp40-43, but the flexibility of the ceramic green body is poor, crack defects are prone to occur, and the strength is not high

Method used

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  • Method for forming water-base casting of sheet-type positive temperature coefficient thermal sensitive ceramic

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0020] 1) BaTiO 3 Preparation of water slurry

[0021] Weigh BaTiO with an average particle size of about 40nm 3 Base PTCR powder 50g, add 7.5g of polyammonium methacrylate aqueous solution with a mass percentage of 10% and deionized water 13.9g, ball mill and mix for 3h.

[0022] 2) BaTiO 3 Preparation of Water-based Casting Slurry

[0023] In BaTiO 3 In the water slurry, add 40g of polyvinyl alcohol aqueous solution with a mass percentage of 10% as a binder, and 2.4g of glycerol as a plasticizer, and ball mill and mix for 3h. After passing through a 250-mesh sieve, BaTiO 3 Water-based casting slurry based on PTCR ceramics.

[0024] 3) Nano BaTiO 3 Preparation of water-based tape casting green body based on PTCR ceramic powder

[0025] The slurry was cast on a casting device at a speed of 1 cm / s, and the obtained wet film was dried in air for 10 hours to obtain a ceramic green body.

[0026] 4) Firing of chip PTCR ceramics

[0027] The water-based tape-cast ceramic g...

Embodiment 2

[0031] 1) BaTiO 3 Preparation of water slurry

[0032] Weigh BaTiO with an average particle size of about 20nm 3 Base PTCR powder 50g, add 10g of polyammonium methacrylate aqueous solution with a mass percentage of 15% and deionized water 6.7g, ball mill and mix for 5h.

[0033] 2) BaTiO 3 Preparation of Water-based Casting Slurry

[0034] In BaTiO 3 In the water slurry, add 47.5g of polyvinyl alcohol aqueous solution with a mass percentage of 10% as a binder, and 3.8g of dibutyl phthalate as a plasticizer, ball mill and mix for 2 hours, and pass through a 250-mesh sieve to obtain BaTiO 3 Water-based casting slurry based on PTCR ceramics.

[0035] 3) Nano BaTiO 3 Preparation of water-based tape casting green body based on PTCR ceramic powder

[0036] The slurry was cast on a casting device at a speed of 1.7 cm / s, and the obtained wet film was dried in air for 24 hours to obtain a ceramic green body.

[0037] 4) Sintering of chip PTC ceramics

[0038] The water-based ...

Embodiment 3

[0042] 1) BaTiO 3 Preparation of water slurry

[0043] Weigh the BaTiO with an average particle size of 70nm 3 Base PTCR powder 50g, add 5g of ammonium polyacrylate aqueous solution with a mass percentage of 20% and deionized water 11.7g, ball mill and mix for 4h.

[0044] 2) BaTiO 3 Preparation of Water-based Casting Slurry

[0045] In BaTiO 3 In the water slurry, add 7.3g of polyethylene glycol emulsion with a mass percentage of 55% as a binder, and 3.1g of polyethylene glycol as a plasticizer, ball mill and mix for 3 hours, and pass through a 250-mesh sieve to obtain BaTiO 3 Water-based casting slurry based on PTCR ceramics.

[0046]3) Nano BaTiO 3 Preparation of water-based tape casting green body based on PTCR ceramic powder

[0047] The slurry was cast on a casting device at a speed of 2 cm / s, and the obtained wet film was dried in air for 20 hours to obtain a ceramic green body.

[0048] 4) Firing of chip PTCR ceramics

[0049] The water-based tape-cast ceramic...

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Abstract

The invention discloses a water-based tape casting method for sheet-shaped positive temperature coefficien heat-sensitive ceramics. The method comprises the following steps: 1) adding deionized water and dispersing agent in nano-sized BaTiO3-based positive temperature coefficient heat-sensitive ceramic powder, and mixing by a ball mill for 3-5 hours to obtain a BaTiO3 slurry; 2) adding binder and plasticizer in the BaTiO3 slurry, mixing by the ball mill for 2-3 hours, and sieving to obtain a water-based casting slurry; 3) performing casting treatment of the water-based casting slurry, drying the wet film obtained after casting treatment to obtain a ceramic blank; and 4) cutting the ceramic blank to square shape and sintering to obtain sheet-shaped positive temperature coefficien heat-sensitive ceramic. The produced ceramic blank has smooth surface, high strength, good flexibility and adaptivity for winding and curling. The produced sheet-shaped positive temperature coefficien heat-sensitive ceramic is widely used for the overcurrent protection and overheat protection in the fields of portable mobile telephones, high-resolution color televisions, auto electronics and hybrid integrated circuits.

Description

technical field [0001] The invention relates to the technical field of sheet-type ceramic materials, and relates to a green molding method for sheet-type positive temperature coefficient heat-sensitive ceramics. Background technique [0002] Chip BaTiO 3 Positive Temperature Coefficient of Resistance heat-sensitive materials (Positive Temperature Coefficient of Resistance referred to as PTCR) are high-performance ceramic materials. One of the research focuses of high-performance ceramics is to improve the reliability of ceramics. The poor reliability of ceramic materials is caused by the brittleness and It is determined by the preparation method of ceramics (such as powder preparation, molding method, drying process and sintering process). Among them, molding is an important part of the ceramic preparation process, which plays a role in linking the past and the future, and is important for improving ceramic products. performance has a great impact. This is due to the ubiqu...

Claims

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Application Information

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IPC IPC(8): C04B35/468C04B35/622
Inventor 周东祥龚树萍郑志平傅邱云刘欢胡云香赵俊
Owner HUAZHONG UNIV OF SCI & TECH
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