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CN-122010556-A - PTC ceramic material with high stability and preparation method thereof

CN122010556ACN 122010556 ACN122010556 ACN 122010556ACN-122010556-A

Abstract

The application provides a PTC ceramic material with high stability and a preparation method thereof, the method comprises the following steps of S1, providing 100 parts by mass of barium titanate and 0.05-0.5 part by mass of donor element source as main phase raw materials, S2, mixing the main phase raw materials, carrying out presintering treatment in an oxidizing atmosphere to uniformly distribute donor elements in the main phase raw materials to obtain a ceramic precursor, S3, smashing 100 parts by mass of the ceramic precursor, mixing and pressing the smashed ceramic precursor with 0.2-1 part by mass of nonmetal oxide, 0.05-0.5 part by mass of fluorine source and 0.03-0.3 part by mass of acceptor element source, and carrying out reduction sintering treatment in a reducing atmosphere to obtain the ceramic material, and S4, carrying out reoxidation treatment on the ceramic material to enable a crystal boundary to form a PTC barrier, thereby obtaining the PTC ceramic material with high stability. The PTC ceramic material obtained by the method has lower room temperature resistance drift rate.

Inventors

  • WEI BING
  • ZHOU WU

Assignees

  • 宜都市博通电子有限责任公司

Dates

Publication Date
20260512
Application Date
20260410

Claims (10)

  1. 1. A method of preparing a PTC ceramic material of high stability comprising the steps of: S1, providing 100 parts by mass of barium titanate and 0.05-0.5 part by mass of donor element source as main phase raw materials; s2, mixing the main phase raw materials, and then performing presintering treatment in an oxidizing atmosphere to uniformly distribute donor elements in the main phase raw materials to obtain a ceramic precursor; s3, after 100 parts by mass of the ceramic precursor are crushed, mixing and pressing with 0.2-1 part by mass of non-metal oxide, 0.05-0.5 part by mass of fluorine source and 0.03-0.3 part by mass of acceptor element source, and then carrying out reduction sintering treatment in a reducing atmosphere, wherein the non-metal oxide comprises silicon oxide and boron oxide, the mass ratio of the silicon oxide to the boron oxide is 1:0.3-0.9, the ceramic precursor forms n-type conductive grains, and the silicon oxide, the boron oxide and the fluorine source are melted in a grain boundary region to form a B-Si-O-F glass phase layer, so that a ceramic material is obtained; s4, re-oxidizing the ceramic material to enable the crystal boundary to form a crystal boundary barrier structure, so that the PTC ceramic material with high stability is obtained.
  2. 2. The method of claim 1, wherein the donor element source comprises at least one of Nb 2 O 5 、Ta 2 O 5 、Sb 2 O 5 and the acceptor element source comprises at least one of MnO 2 、Mn 2 O 3 .
  3. 3. The method according to claim 1, wherein the pre-sintering treatment in step S2 is performed under an oxidizing atmosphere at a temperature rising rate of 2-5 ℃ per minute to 1000-1200 ℃ for 1-4 hours.
  4. 4. The method according to claim 1, wherein in the step S3, the mass ratio of the non-metal oxide to the fluorine source is 1:0.1-0.5.
  5. 5. The method according to claim 4, wherein the step S3 further comprises mixing 100 parts by mass of the ceramic precursor with 0.2 to 1 part by mass of the nonmetallic oxide, 0.05 to 0.5 part by mass of the fluorine source, 0.03 to 0.3 part by mass of the acceptor element source and 0.01 to 0.2 part by mass of CeO 2 , press-molding, and then subjecting to a reduction sintering treatment in a reducing atmosphere.
  6. 6. The method according to claim 1, wherein in the step S3, the conditions of the reduction sintering treatment include heating to 1250-1400 ℃ at a temperature rising rate of 2-5 ℃ per min under a reducing atmosphere for sintering for 1-3 hours.
  7. 7. The method of claim 1, wherein in step S3, the fluorine source comprises at least one of BaF 2 、SrF 2 .
  8. 8. The method according to claim 1, wherein in the step S4, the reoxidation treatment is performed under an oxidizing atmosphere at a temperature rising rate of 2-5 ℃ per minute to 700-900 ℃ for 1-5 hours.
  9. 9. The method according to any one of claims 1 to 8, wherein in step S4, the reoxidation treatment is followed by an annealing treatment, and the annealing treatment is performed under a condition including a heat preservation at 600 to 800 ℃ for 1 to 3 hours.
  10. 10. A PTC ceramic material of high stability, characterized in that it is prepared by a method according to any one of claims 1 to 9.

Description

PTC ceramic material with high stability and preparation method thereof Technical Field The application relates to the technical field of ceramic materials, in particular to a PTC ceramic material with high stability and a preparation method thereof. Background Positive temperature coefficient (Positive Temperature Coefficient, PTC) ceramic materials are a class of functional materials whose resistance increases sharply with increasing temperature around curie temperature, and are widely used in the fields of overcurrent protection elements, self-temperature limiting heaters, temperature compensation devices, battery protection systems, and the like. Among them, the semiconductor PTC ceramics using barium titanate (BaTiO 3) as matrix is the most widely used PTC material due to its wide adjustable range of electrical properties, low cost and relatively mature process. The existing BaTiO 3 -based PTC ceramic generally forms an n-type conductive structure in the crystal grains through donor doping, and forms a potential barrier structure in a crystal boundary region through a reduction-reoxidation process, so that the transition characteristic of the resistor near the Curie temperature is realized. However, the problem of long-term stability of PTC ceramic materials is increasingly pronounced during practical applications. Since the PTC effect depends on the electrical difference between the grains and the grain boundaries, when the material is used under a long-term thermal stress, an electrical stress, or an environmental change condition, the defect distribution and the oxygen vacancy concentration of the grain boundary region are easily changed, and the diffusion and redistribution of oxygen in the grain boundary region are difficult to be effectively controlled, thereby causing the fluctuation of the barrier height, thereby causing the drift of the room temperature resistance and the high temperature resistance characteristics. Part of PTC ceramics in the prior art can have the phenomenon that the room temperature resistance gradually rises or decreases under the condition of high-temperature aging or long-time electrifying, the electrical property repeatability and consistency are difficult to ensure, and the reliability and the service life of the device are affected. In addition, the multicomponent doping system may react with each other or diffuse unevenly during the high temperature sintering process, which results in uneven grain growth or unstable grain boundary phase distribution, further exacerbating the fluctuation of the electrical properties of the material. The traditional process is also sensitive to control of reduction and reoxidation steps, and if the atmosphere, the temperature or the time are controlled improperly, the conductive structure inside the crystal grains is insufficient or the grain boundary potential barrier is formed incompletely, so that the PTC characteristic and the long-term stability of the material are difficult to be compatible. Therefore, how to realize long-term cooperative stabilization of the grain conductive structure and the grain boundary barrier structure while ensuring the PTC transition characteristic, reduce the resistance drift rate and improve the consistency and reliability of materials becomes a technical problem to be solved in the field. Disclosure of Invention The application provides a PTC ceramic material with high stability and a preparation method thereof, which solve the problem that the existing PTC ceramic material has higher room temperature resistance drift rate under the action of long-term thermal stress or electric stress, thereby reducing the room temperature resistance drift rate of the PTC ceramic material and improving the long-term use stability of the PTC ceramic material. In a first aspect, the present application provides a method of preparing a PTC ceramic material of high stability, comprising the steps of: S1, providing 100 parts by mass of barium titanate and 0.05-0.5 part by mass of donor element source as main phase raw materials; s2, mixing the main phase raw materials, and then performing presintering treatment in an oxidizing atmosphere to uniformly distribute donor elements in the main phase raw materials to obtain a ceramic precursor; s3, after 100 parts by mass of the ceramic precursor are crushed, mixing and pressing with 0.2-1 part by mass of non-metal oxide, 0.05-0.5 part by mass of fluorine source and 0.03-0.3 part by mass of acceptor element source, and then carrying out reduction sintering treatment in a reducing atmosphere, wherein the non-metal oxide comprises silicon oxide and boron oxide, the mass ratio of the silicon oxide to the boron oxide is 1:0.3-0.9, the ceramic precursor forms n-type conductive grains, and the silicon oxide, the boron oxide and the fluorine source are melted in a grain boundary region to form a B-Si-O-F glass phase layer, so that a ceramic material is obtained; s4, re-oxidizing the ce