CN105130425A - High-curie-point positive-temperature-coefficient resistive material Ba5ZnTi3O12 and preparation method thereof - Google Patents

Abstract

The invention discloses a lead-free high-curie-point positive-temperature-coefficient resistive material and a preparation method thereof. The chemical composition formula of the high-curie-point positive-temperature-coefficient resistive material is Ba5ZnTi3O12. Original powder of BaCO3, ZnO and TiO2 are weighed and mixed according to the composition of BaZnTi3O12, wherein the purity of the original powder is above 99.9% (weight percentage); through ball milling, calcining, secondary ball milling, granulating, forming, binder removal, high-temperature sintering and Ag electrode applying, the lead-free positive-temperature-coefficient resistive material is obtained, wherein the curie point of the resistive material is up to 385 DEG C. The obtained resistive material does not contain lead, and therefore hurt to body health of people and pollution to the environment of lead are avoided. The resistive material is low in sintering temperature and raw material cost and suitable for large-scale industrialized production, and reaches the practical level.

Description

A kind of high curie point positive temperature coefficient resistance material Ba 5znTi 3o 12and preparation method thereof

Technical field

The present invention relates to a kind of unleaded positive temperature coefficient resistance material and preparation method thereof, belong to thermo-sensitive material field.

Background technology

PTC pottery (positive temperature coefficient thermal sensitive ceramic) has resistivity and raises and the feature of increase with temperature.It is development in recent years one of electronic material rapidly.Posistor can be divided into switching mode and the large class of offset-type two, and its characteristic and application is also different.Switching mode positive temperature coefficient thermo-sensitive material is mainly used in the protection etc. of rectifier cell of motor, transformer, bearing, high-power silicon, and it is also applied to the aspects such as current limliting, current stabilization, voltage stabilizing and velocity measurement as hear rate element.Offset-type positive temperature coefficient thermo-sensitive material can be used as the temperature compensation of transistor.

Barium titanate-based positive temperature coefficient thermo-sensitive material is a kind of Ferro-Electric Semiconductor material, is development in recent years one of electronic material rapidly.But the Curie temperature of barium titanate only has 120 DEG C, the PTC thermo-sensitive material of Curie temperature more than 120 DEG C is all leaded in the market.Domestic and international raising barium titanate positive temperature coefficient transition temperature mainly realizes by adding lead element.Although this kind of method and technology is more ripe and obtained good effect, lead has very strong toxicity.Products containing lead uses from being prepared into and even all there is very strong harm to last recycling use.Start to completely forbid use in the world in 2006 and had plumbous piezo component.In recent years, along with the demand of environment protection and human kind sustainable development, research novel lead-free PTC resistive material is extremely urgent.Nowadays unleaded positive temperature coefficient thermo-sensitive material mainly macromolecular material, but due to the hot mastication of macromolecular material, greatly limit its use range.Therefore find unleaded high-curie temperature positive temperature coefficient thermo-sensitive material tool and have very important significance.A lot of Chinese patent is had to report environment-friendly type positive temperature coefficient thermo-sensitive material, as (Ba _x sr _y ca _z ) Ti _u o ₃, wherein, x: 0.6 ~ 0.9, y: 0 ~ 0.3, z: 0.02 ~ 0.2, u: 0.98 ~ 1.02; : (Bi _1/2k _{1/2- a/ 2} na _a/2) Ce _{1- b} dbO ₃, wherein a=0 ~ 1, b=0.0005 ~ 0.005 etc., but Curie temperature not high (lower than 160 DEG C).Tang Xingui etc. report BaTiO ₃-Bi _0.5na _0.5tiO ₃-Bi _0.5k _0.5tiO ₃be positive temperature coefficient thermo-sensitive material, it comprehensively employs sol-gel method, solid reaction process, discharge plasma sintering method, and by adulterating prepared by one or more metal oxides, but the highest Curie temperature is also no more than 250 DEG C.

Summary of the invention

The object of this invention is to provide a kind of unleaded high curie point positive temperature coefficient resistance material and preparation method thereof.

The unleaded high curie point positive temperature coefficient resistance material that the present invention relates to chemical constitution formula be: Ba ₅znTi ₃o ₁₂.

Preparation method's concrete steps of above-mentioned unleaded high curie point positive temperature coefficient resistance material are:

(1) be 99.9%(weight percent by purity) more than BaCO ₃, ZnO and TiO ₂starting powder press Ba ₅znTi ₃o ₁₂composition weigh batching.

(2) material step (1) prepared through ball milling 4 hours, 1200 DEG C of pre-burnings 2 hours, secondary ball milling 3 hours, granulation, compressing tablet, binder removal, calcine 3 hours for 1250 ~ 1300 DEG C, upper Ag electrode, i.e. obtained high curie point positive temperature coefficient resistance material Ba ₅znTi ₃o ₁₂.

High curie point positive temperature coefficient resistance material Ba prepared by the present invention ₅znTi ₃o ₁₂have the following advantages: have high Curie temperature, sintering temperature is low, and raw materials cost is low; Composition is unleaded, can not work the mischief to environment with to human body.

Embodiment

embodiment 1:

Be 99.9%(weight percent by purity) more than BaCO ₃, ZnO and TiO ₂starting powder press Ba ₅znTi ₃o ₁₂composition weigh batching; Then by the material planetary mills ball milling for preparing 4 hours, 1200 DEG C of pre-burnings 2 hours, secondary ball milling 3 hours, granulation, compressing tablet, binder removal, 1250 DEG C of calcinings 3 hours, upper Ag electrode, prepares sample; Performance test is carried out to obtained sample, its Curie temperature t _c ≈ 385 DEG C, resistivity is 8.9 Ω m, temperature factor is 11.9%/DEG C, maximum resistance rate/lowest resistivity (liftdrag) is greater than 1.30 × 10 ⁴.

embodiment 2:

Be 99.9%(weight percent by purity) more than BaCO ₃, ZnO and TiO ₂starting powder press Ba ₅znTi ₃o ₁₂composition weigh batching; Then by the material planetary mills ball milling for preparing 4 hours, 1200 DEG C of pre-burnings 2 hours, secondary ball milling 3 hours, granulation, compressing tablet, binder removal, 1275 DEG C of calcinings 3 hours, upper Ag electrode, prepares sample; Performance test is carried out to obtained sample, its Curie temperature t _c ≈ 385 DEG C, resistivity is 7.8 Ω m, temperature factor is 14.6%/DEG C, maximum resistance rate/lowest resistivity (liftdrag) is greater than 1.49 × 10 ⁴.

embodiment 3:

Be 99.9%(weight percent by purity) more than BaCO ₃, ZnO and TiO ₂starting powder press Ba ₅znTi ₃o ₁₂composition weigh batching; Then by the material planetary mills ball milling for preparing 4 hours, 1200 DEG C of pre-burnings 2 hours, secondary ball milling 3 hours, granulation, compressing tablet, binder removal, 1300 DEG C of calcinings 3 hours, top electrode, prepares sample; Performance test is carried out to obtained sample, its Curie temperature t _c ≈ 385 DEG C, resistivity is 9.7 Ω m, temperature factor is 13.5%/DEG C, maximum resistance rate/lowest resistivity (liftdrag) is greater than 1.41 × 10 ⁴.

Claims (1)

1. high curie point positive temperature coefficient resistance material and preparation method thereof, is characterized in that the chemical constitution formula of described positive temperature coefficient resistance material is: Ba ₅znTi ₃o ₁₂;

Preparation method's concrete steps of described positive temperature coefficient resistance material are:

(1) be 99.9%(weight percent by purity) more than BaCO ₃, ZnO and TiO ₂starting powder press Ba ₅znTi ₃o ₁₂composition weigh batching;

(2) material step (1) prepared through ball milling 4 hours, 1200 DEG C of pre-burnings 2 hours, secondary ball milling 3 hours, granulation, compressing tablet, binder removal, calcine 3 hours for 1250 ~ 1300 DEG C, upper Ag electrode, i.e. obtained high curie point positive temperature coefficient resistance material Ba ₅znTi ₃o ₁₂.