High-Curie-point low-resistivity lead-free PTCR (Positive Temperature Coefficient of Resistance) ceramic material and preparation method thereof

A technology with low resistivity and high Curie point, applied in the field of functional ceramic materials, can solve the problems of Bi element volatilization, sodium ion loss, material chemical ratio deviation, etc., to avoid grain growth and agglomeration, and avoid ion loss , the effect of obvious diffraction peak intensity

Inactive Publication Date: 2010-09-15
HUAZHONG UNIV OF SCI & TECH +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The above-mentioned materials have high resistivity, small lift-to-drag ratio, and poor overall PTC effect, which cannot meet the technical requirements of low-voltage applications (such as low-voltage electrical appliances such as automotive air conditioners)
[0005] Generally all adopt traditional solid phase sintering method (comprising Chinese invention patents such as above-mentioned CN10128473A, CN 101284731A) aspect preparation technology, in initial mixing, generally all adopt deionized water as medium to carry out wet ball milling, because sodium salt belongs to Water-soluble salts can easily cause the loss of sodium ions during the bal...

Method used

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  • High-Curie-point low-resistivity lead-free PTCR (Positive Temperature Coefficient of Resistance) ceramic material and preparation method thereof
  • High-Curie-point low-resistivity lead-free PTCR (Positive Temperature Coefficient of Resistance) ceramic material and preparation method thereof

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preparation example Construction

[0030] The preparation method of the semiconductor ceramic material involved in the present invention includes batching, polymer in-situ solidification to prepare gel, low-temperature synthesis to prepare nano-powder satisfying chemical dosage ratio, and low-temperature firing to prepare lead-free PTCR ceramics with high Curie point and low resistivity. Specific steps are as follows:

[0031] 1. Prepare the solution

[0032]The initial raw materials are all related metal oxides with a purity of 99.8% and above, such as Bi 2 o 3 、Sm 2 o 3 、Nd 2 o 3 , Y 2 o 3 , La 2 o 3 etc.; or carbonates such as BaCO 3 , CaCO 3 , SrCO 3 、Na 2 CO 3 、K 2 CO 3 etc.; or metal alkoxides such as butyl titanate Si(OC 2 h 5 ) 4 , Ti(OC 4 h 9 ) 4 and other raw materials. Prepare a mixed solution containing Bi, Na, K, Ba, Ti, Ln, Cn, Si, Mn and other ions according to the molar ratio given in formula ①.

[0033] A preferred mode is listed below to illustrate the preparation proce...

Embodiment 1

[0051] 1. Prepare the solution

[0052] Prepare solutions containing Bi, Na, K, Ba, Ti, Sm, Ca, Si, Mn and other ions respectively:

[0053] Press Bi 2 o 3 : nitric acid=1:7 molar ratio, weigh Bi 2 o 3 and nitric acid, dilute with deionized water in nitric acid, and then dilute the diluted solution with Bi 2 o 3 Mix, heat to 80°C, stir, after the reaction is complete, get the 3+ solution, and add ammonia to pH 7;

[0054] Na 2 CO 3 、K 2 CO 3 Deionized water was added to form an aqueous solution.

[0055] By BaCO 3 : Molar ratio of citric acid=1:4, weighing barium carbonate BaCO 3 with citric acid. First, deionized water was added to citric acid to prepare a citric acid solution, and then the citric acid solution was mixed with BaCO 3 After mixing, after the reaction is completed, a 2+ solution, and add ammonia to pH 7;

[0056] Butyl titanate Ti(OC 4 h 9 ) 4 : citric acid=1:1.1 weight ratio, weigh butyl titanate Ti(OC 4 h 9 ) 4 and citric acid, adding de...

Embodiment 2

[0072] 1. Prepare the solution

[0073] Solutions containing Bi, Na, K, Ba, Ti, Y, Ca, Si, Mn ions were prepared respectively.

[0074] Press Bi 2 o 3 : nitric acid=1:6 molar ratio, weigh Bi 2 o 3 and nitric acid, dilute with deionized water in nitric acid, and then dilute the diluted solution with Bi 2 o 3 Mix, heat to 82°C, stir, after the reaction is complete, get the 3+ solution, and add ammonia to pH 8;

[0075] Na 2 CO 3 、K 2 CO 3 Deionized water was added to form an aqueous solution.

[0076] By BaCO 3 : Molar ratio of citric acid=1:3, weighing barium carbonate BaCO 3 with citric acid. First, deionized water was added to citric acid to prepare a citric acid solution, and then the citric acid solution was mixed with BaCO 3 After mixing, after the reaction is completed, a 2+ solution, and add ammonia to pH 8;

[0077] Butyl titanate Ti(OC 4 h 9 ) 4 : citric acid=1:1 weight ratio, weigh butyl titanate Ti(OC 4 h 9 ) 4 and citric acid, adding deionized...

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Abstract

The invention discloses a high-Curie-point low-resistivity lead-free PTCR (Positive Temperature Coefficient of Resistance) ceramic material with a constitution formula (1): [Bi0.5(Na1-xKx)0.5]y[Ba1-y-z-j]TiO3+zLn3++jCn2++kSi2++wMn(NO3)2. In the formula, x is equal to 0.1-0.5, y is equal to 0.1-0.3, z is equal to 0.001-0.01, j is equal to 0.1-0.2, k is equal to 0.01-0.05, w is equal to 0.0001-0.001, Ln comprises one or two elements of Sm, Nd, Y and La, and Cn comprises at lest one of Ca and Sr. The preparation method comprises the following steps of: (1) respectively preparing solutions containing Bi, Na, K, Ba, Ti, Ln, Cn, Si and Mn ions and preparing a mixed solution according to a mol ratio given in formula (1); (2) mixing the mixed solution, organic monomers and a crosslinking agent according to a proportion of 100ml: (6-20)g: (0.5-8)g and crosslinking and polymerizing the organic monomers and the crosslinking agent in the solution to obtain gel; (3) calcining at 700-800 DEG C for 1-3h to obtain ceramic powder; and (4) granulating the powder, drily pressing to form and calcining at a high temperature of 1200-1300 DEG C for 1-2h. The ceramic material has the advantages of high Curie point and low resistivity.

Description

technical field [0001] The invention belongs to the technical field of functional ceramic materials, in particular to a BaTiO 3 The invention discloses a lead-free PTCR ceramic material with a high Curie point and low resistivity and a preparation method thereof. Background technique [0002] PTCR generally refers to a thermistor material or component with a positive temperature coefficient. A typical PTCR material is a semiconductor ceramic material based on barium titanate. Its characteristic is that when the ambient temperature rises to a certain temperature (Curie point or switch temperature point), its resistance value will increase by several orders of magnitude. Using this material as a heating body, its heating power hardly changes with the change of the applied voltage, so it has the function of automatic constant temperature. At the same time, it is widely used in industrial and military electronic equipment, as well as household appliances and other fields becau...

Claims

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Application Information

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IPC IPC(8): C04B35/468C04B35/624
Inventor 周东祥龚树萍赵俊邱传贡
Owner HUAZHONG UNIV OF SCI & TECH
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