A high-curie temperature low-resistivity PTC thermistor, a formulation and a manufacturing method thereof

Abstract

The application discloses a high-curie-temperature low-resistivity PTC thermistor, a formula and a manufacturing method thereof. The PTC thermistor is composed of a main material, an auxiliary material and a sintering aid. The molar composition of the main material is: TiO2: 1 mol, BaCO3: 0.60-0.72 mol, CaCO3: 0.03-0.10, SrCO3: 0-0.10 and PbO: 0.18-0.31 mol, with 1 mol of TiO2 as a reference; the molar composition of the auxiliary material is: Y2O3: 0.002-0.010 mol; and the molar composition of the sintering aid is: SiO2: 0.010-0.040 mol and TiO2: 0.005-0.015 mol. The ceramic formula proportion of the application and the existing tunnel furnace sintering process can successfully realize the preparation of the PTC thermistor with a curie temperature of 200-260 DEG C and a resistivity of 15-40 ohm-cm. Meanwhile, due to the low-resistivity advantage of the formula, the tunnel furnace sintering and post-processing process are stable, and the application is suitable for mass production.

Description

Technical Field

[0001] This invention belongs to the field of thermistor technology, specifically relating to a high Curie temperature, low resistivity PTC thermistor, its formulation, and its manufacturing method. Background Technology

[0002] PTC thermistors are positive temperature coefficient thermistors, meaning their resistance increases with temperature. These resistors are typically made of barium titanate and manufactured into specially shaped components using various production processes and applications. Utilizing their resistance-temperature, voltage-current, and current-time characteristics, PTC thermistors are widely used in various fields such as home appliances, automobiles, and industry, serving functions such as automatic demagnetization, delayed start-up, constant temperature heating, overcurrent protection, overheat protection, and temperature sensing.

[0003] Constant-temperature heating PTC thermistors possess constant-temperature heating characteristics. Their principle is that after being energized, the PTC thermistor self-heats, causing its resistance to enter a transition region. Once stable, its surface temperature remains constant, depending only on the Curie temperature of the PTC thermistor and the applied voltage, and is largely independent of the ambient temperature. PTC heaters are heating devices designed using the constant-temperature heating characteristics of PTC thermistors. In low-to-medium power heating applications, PTC heaters offer unparalleled advantages over traditional heating elements, including constant-temperature heating, no open flame, high heat conversion rate, minimal impact from power supply voltage, and long lifespan. Their application in electric heating appliances is increasingly favored by R&D engineers. Constant-temperature heating PTC thermistors can be manufactured in various shapes and specifications, commonly including discs, rectangles, strips, rings, and honeycomb porous structures. Combining PTC thermistors with metal components can create various forms of PTC heaters with different power requirements.

[0004] Traditional PTC thermistors for constant-temperature heating use BaTiO3 as the ceramic matrix, and PbO is added to the ceramic material as a Curie temperature adjuster to adjust the Curie temperature of the thermistor. Theoretically, the Curie temperature of BaTiO3-based ceramic is around 120℃, and adding 1 mol% Pb generally increases the Curie temperature by 3.5~4.0℃. If the Curie temperature of the PTC thermistor needs to reach above 250℃, it is theoretically expected that more than 25 mol% PbO needs to be added. Adding PbO to BaTiO3-based ceramic PTC thermistors can, on the one hand, increase the Curie temperature of the PTC, and on the other hand, it can refine the grain and improve the withstand voltage during the PTC sintering and semiconductorization process. With the increase of PbO content in the ceramic material, the resistivity of the PTC thermistor will increase significantly. For general high-voltage, high-power applications, high-resistivity PTC thermistors are easier to achieve. However, for applications requiring low voltage and high heating temperatures, low-resistivity PTC thermistors are difficult to manufacture.

[0005] 1. Traditional ceramic material formulations combined with existing tunnel furnace sintering processes make it difficult to achieve high Curie temperature and low resistivity PTC thermistors, especially for products requiring Curie temperatures above 200℃ and resistivity below 100Ω·cm, which presents even greater challenges.

[0006] 2. Even with special manufacturing processes, the resistance of the products produced will vary greatly, resulting in a very low batch production qualification rate.

[0007] 3. Due to the instability of the manufacturing process, the basic characteristics of PTC thermistors (such as RT and VI characteristics) fluctuate greatly, posing a significant safety risk to customers when using them. Summary of the Invention

[0008] To overcome the aforementioned shortcomings, the inventors of this invention, through long-term exploration, experimentation, and continuous innovation, have proposed a high Curie temperature, low resistivity PTC thermistor, its formulation, and its manufacturing method. This method utilizes the ceramic material formulation of this invention, combined with existing tunnel furnace sintering processes, to successfully prepare PTC thermistors with a Curie temperature of 200-260℃ and a resistivity of 15-40 Ω·cm. Furthermore, due to the low resistivity advantage of the formulation, the tunnel furnace sintering and post-processing are stable, making it suitable for mass production.

[0009] To achieve the above objectives, the technical solution adopted by this invention is: to provide a high Curie temperature, low resistivity PTC thermistor formulation. Raw material composition and proportions: composed of main materials, auxiliary materials, and sintering aids, based on 1 mol of TiO2: The molar composition of the main material is as follows: TiO2: 1 mol, BaCO3: 0.60~0.72 mol, CaCO3: 0.03~0.10 mol, SrCO3: 0~0.10, PbO: 0.18~0.31 mol; The molar composition of the auxiliary materials is as follows: Y₂O₃: 0.002~0.010 mol; The molar composition of the sintering aid is as follows: SiO2: 0.010~0.040 mol TiO2: 0.005~0.015mol.

[0010] A further preferred embodiment of the high Curie temperature, low resistivity PTC thermistor formulation according to the present invention is as follows: for a Curie temperature of 200°C, the raw material composition and proportions are as follows: The molar composition of the main material is as follows: TiO2: 1 mol, BaCO3: 0.60~0.70 mol CaCO3: 0.06~0.10 mol, SrCO3: 0.03~0.07 mol, PbO: 0.19~0.23 mol; The molar composition of the auxiliary materials is as follows: Y₂O₃: 0.003~0.009 mol; The molar composition of the sintering aid is as follows: SiO2: 0.012~0.035 mol TiO2: 0.006~0.012 mol.

[0011] A further preferred embodiment of the high Curie temperature, low resistivity PTC thermistor formulation according to the present invention is as follows: for a Curie temperature of 200°C, the raw material composition and proportions are as follows: The molar composition of the main material is as follows: TiO2: 1 mol, BaCO3: 0.62~0.68 mol CaCO3: 0.07~0.09 mol, SrCO3: 0.04~0.06 mol, PbO: 0.20~0.22 mol; The molar composition of the auxiliary materials is as follows: Y₂O₃: 0.004~0.006 mol; The molar composition of the sintering aid is as follows: SiO2: 0.015~0.030 mol TiO2: 0.006~0.010 mol.

[0012] A further preferred embodiment of the high Curie temperature, low resistivity PTC thermistor formulation according to the present invention is as follows: for a Curie temperature of 260°C, the raw material composition and proportions are as follows: The molar composition of the main material is as follows: TiO2: 1 mol, BaCO3: 0.62~0.72 mol, CaCO3: 0.03~0.07 mol, PbO: 0.26~0.30 mol; The molar composition of the auxiliary materials is as follows: Y₂O₃: 0.003~0.009 mol; The molar composition of the sintering aid is as follows: SiO2: 0.012~0.035 mol TiO2: 0.006~0.012 mol.

[0013] A further preferred embodiment of the high Curie temperature, low resistivity PTC thermistor formulation according to the present invention is as follows: for a Curie temperature of 260°C, the raw material composition and proportions are as follows: The molar composition of the main material is as follows: TiO2: 1 mol, BaCO3: 0.64~0.70 mol CaCO3: 0.04~0.06 mol, PbO: 0.27~0.29 mol; The molar composition of the auxiliary materials is as follows: Y₂O₃: 0.004~0.006 mol; The molar composition of the sintering aid is as follows: SiO2: 0.015~0.030 mol TiO2: 0.006~0.010 mol.

[0014] A method for manufacturing a high Curie temperature and low resistivity PTC thermistor includes the following steps: 1) According to the required performance of the thermistor, weigh the raw materials according to the above-mentioned raw material composition and proportion, and mix the weighed raw materials in a ball mill at a mass ratio of raw materials: grinding balls: deionized water = 1:2:2. 2) Dry the powder after one ball milling and pre-calcine it at 1050~1100℃ for 3 hours; 3) The pre-calcined powder is ball-milled again according to the mass ratio of powder:grinding balls:deionized water = 1:2:2; 4) Dry the powder after the second ball milling, mix it thoroughly with the powder in a ratio of 100:17 (powder:13% polyvinyl alcohol solution), granulate it, and then dry it. 5) Press the powder into circular ceramic green bodies; 6) The ceramic green body is loaded into a sintering sagger and rapidly sintered into a ceramic body in a tunnel furnace at 1280~1300℃; 7) Print silver-zinc ohmic silver paste and surface silver paste on the front and back surfaces of the sintered ceramic body, and prepare silver electrodes by firing at 520℃ for 10~20 min; 8) The resistance value of the chip used to prepare the electrode is measured and the appearance is sorted to obtain the finished PTC thermistor.

[0015] A further preferred embodiment of the method for manufacturing a high Curie temperature, low resistivity PTC thermistor according to the present invention is as follows: in step 5), the circular ceramic green body has a diameter of φ=6.15mm and a diameter of T=1.12mm.

[0016] A high Curie temperature, low resistivity PTC thermistor is manufactured by the above method.

[0017] Compared with the prior art, the technical solution of the present invention has the following advantages / benefits: 1. By adopting the ceramic material formulation ratio of this invention and combining it with the existing tunnel furnace sintering process, PTC thermistors with a Curie temperature of 200~260℃ and a resistivity of 15~40Ω·cm can be successfully prepared. Furthermore, due to the low resistivity advantage of the formulation, the tunnel furnace sintering and post-processing are stable, making it suitable for mass production.

[0018] 2. Using the formula ratio and processing method of this invention, the resistance qualification rate of the product is relatively high, reaching over 90%.

[0019] 3. Due to the stability of the process, the basic characteristics of PTC thermistors (such as RT and VI characteristics) fluctuate less, making them safer for customers to use. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0021] Figure 1 This is a flowchart of a method for manufacturing a high Curie temperature, low resistivity PTC thermistor according to the present invention. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention are described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of this invention, not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this invention. Therefore, the detailed description of the embodiments of this invention provided below is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the invention.

[0023] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.

[0024] Example 1: A formulation for a high Curie temperature, low resistivity PTC thermistor. Raw material composition and proportions: Composed of main materials, auxiliary materials, and sintering aids, based on 1 mol TiO2. The molar composition of the main material is as follows: TiO2: 1 mol, BaCO3: 0.68 mol CaCO3: 0.08 mol SrCO3: 0.05 mol PbO: 0.19 mol; The molar composition of the auxiliary materials is as follows: Y2O3: 0.005 mol; The molar composition of the sintering aid is as follows: SiO2: 0.022 mol TiO2: 0.008 mol.

[0025] like Figure 1 As shown, a method for manufacturing high Curie temperature and low resistivity PTC thermistors is proposed for the above formula. The steps include: 1) According to the required performance of the thermistor, the raw materials are weighed according to the above raw material composition and proportion. The weighed raw materials are ball-milled and mixed once according to the mass ratio of raw materials: grinding balls: deionized water = 1:2:2. This step mainly mixes the raw material powder to facilitate subsequent pre-firing. 2) Dry the powder after one ball milling and pre-calcine it at 1080℃ for 3 hours; 3) The pre-calcined powder is ball-milled again according to the mass ratio of powder:grinding ball:deionized water = 1:2:2. This step is mainly to crush the powder that has become lumpy after pre-calcination. 4) Dry the powder after the second ball milling, mix it thoroughly with the powder in a ratio of 100:17 (powder:13% polyvinyl alcohol solution), granulate it, and then dry it. 5) Press the powder into circular ceramic green bodies; the circular ceramic green bodies have a diameter of φ=6.15mm and a diameter of T=1.12mm; 6) The ceramic green body is loaded into a sintering sagger and rapidly sintered into a ceramic body at 1290℃ in a tunnel furnace; 7) Print silver-zinc ohmic silver paste and surface silver paste on the front and back surfaces of the sintered ceramic body, and prepare silver electrodes by firing at 520℃ for 15 min; 8) The resistance value of the electrode chip is measured and the appearance is sorted to obtain the finished PTC thermistor. The Curie temperature of the finished product is 211℃ and the resistivity is 16Ω·cm.

[0026] Example 2: A formulation for a high Curie temperature, low resistivity PTC thermistor. Raw material composition and proportions: Composed of main materials, auxiliary materials, and sintering aids, based on 1 mol TiO2. The molar composition of the main material is as follows: TiO2: 1 mol, BaCO3: 0.66 mol CaCO3: 0.08 mol SrCO3: 0.05 mol PbO: 0.21 mol; The molar composition of the auxiliary materials is as follows: Y2O3: 0.005 mol; The molar composition of the sintering aid is as follows: SiO2: 0.022 mol TiO2: 0.008 mol.

[0027] like Figure 1 As shown, a method for manufacturing a high Curie temperature and low resistivity PTC thermistor is proposed for the above formula. The steps include: 1) According to the required performance of the thermistor, weigh the raw materials according to the above raw material composition and proportion, and mix the weighed raw materials in a ball milling process according to the mass ratio of raw materials: grinding balls: deionized water = 1:2:2. 2) Dry the powder after one ball milling and pre-calcine it at 1080℃ for 3 hours; 3) The pre-calcined powder is ball-milled again according to the mass ratio of powder:grinding balls:deionized water = 1:2:2; 4) Dry the powder after the second ball milling, mix it thoroughly with the powder in a ratio of 100:17 (powder:13% polyvinyl alcohol solution), granulate it, and then dry it. 5) Press the powder into circular ceramic green bodies; the circular ceramic green bodies have a diameter of φ=6.15mm and a diameter of T=1.12mm; 6) The ceramic green body is loaded into a sintering sagger and rapidly sintered into a ceramic body at 1290℃ in a tunnel furnace; 7) Print silver-zinc ohmic silver paste and surface silver paste on the front and back surfaces of the sintered ceramic body, and prepare silver electrodes by firing at 520℃ for 15 min; 8) The resistance value of the chip used to prepare the electrode is measured and the appearance is sorted to obtain the finished PTC thermistor. The Curie temperature of the finished product is 219℃ and the resistivity is 21Ω·cm.

[0028] Example 3: A formulation for a high Curie temperature, low resistivity PTC thermistor. Raw material composition and proportions: Composed of main materials, auxiliary materials, and sintering aids, based on 1 mol TiO2. The molar composition of the main material is as follows: TiO2: 1 mol, BaCO3: 0.64 mol CaCO3: 0.08 mol SrCO3: 0.05 mol PbO: 0.23 mol; The molar composition of the auxiliary materials is as follows: Y2O3: 0.005 mol; The molar composition of the sintering aid is as follows: SiO2: 0.022 mol TiO2: 0.008 mol.

[0029] like Figure 1 As shown, a method for manufacturing a high Curie temperature and low resistivity PTC thermistor is proposed for the above formula. The steps include: 1) According to the required performance of the thermistor, weigh the raw materials according to the above raw material composition and proportion, and mix the weighed raw materials in a ball milling process according to the mass ratio of raw materials: grinding balls: deionized water = 1:2:2. 2) Dry the powder after one ball milling and pre-calcine it at 1070℃ for 3 hours; 3) The pre-calcined powder is ball-milled again according to the mass ratio of powder:grinding balls:deionized water = 1:2:2; 4) Dry the powder after the second ball milling, mix it thoroughly with the powder in a ratio of 100:17 (powder:13% polyvinyl alcohol solution), granulate it, and then dry it. 5) Press the powder into circular ceramic green bodies; the circular ceramic green bodies have a diameter of φ=6.15mm and a diameter of T=1.12mm; 6) The ceramic green body is loaded into a sintering sagger and rapidly sintered into a ceramic body at 1290℃ in a tunnel furnace; 7) Print silver-zinc ohmic silver paste and surface silver paste on the front and back surfaces of the sintered ceramic body, and prepare silver electrodes by firing at 520℃ for 15 min; 8) The resistance value of the electrode chip is measured and the appearance is sorted to obtain the finished PTC thermistor. The Curie temperature of the finished product is 227℃ and the resistivity is 25Ω·cm.

[0030] Example 4: A formulation for a high Curie temperature, low resistivity PTC thermistor. Raw material composition and proportions: Composed of main materials, auxiliary materials, and sintering aids, based on 1 mol TiO2. The molar composition of the main material is as follows: TiO2: 1 mol, BaCO3: 0.69 mol CaCO3: 0.05 mol SrCO3: 0 mol PbO: 0.26 mol; The molar composition of the auxiliary materials is as follows: Y2O3: 0.005 mol; The molar composition of the sintering aid is as follows: SiO2: 0.022 mol TiO2: 0.008 mol.

[0031] like Figure 1 As shown, a method for manufacturing a high Curie temperature and low resistivity PTC thermistor is proposed for the above formula. The steps include: 1) According to the required performance of the thermistor, weigh the raw materials according to the above raw material composition and proportion, and mix the weighed raw materials in a ball milling process according to the mass ratio of raw materials: grinding balls: deionized water = 1:2:2. 2) Dry the powder after one ball milling and pre-calcine it at 1070℃ for 3 hours; 3) The pre-calcined powder is ball-milled again according to the mass ratio of powder:grinding balls:deionized water = 1:2:2; 4) Dry the powder after the second ball milling, mix it thoroughly with the powder in a ratio of 100:17 (powder:13% polyvinyl alcohol solution), granulate it, and then dry it. 5) Press the powder into circular ceramic green bodies; the circular ceramic green bodies have a diameter of φ=6.15mm and a diameter of T=1.12mm; 6) The ceramic green body is loaded into a sintering sagger and rapidly sintered into a ceramic body at 1290℃ in a tunnel furnace; 7) Print silver-zinc ohmic silver paste and surface silver paste on the front and back surfaces of the sintered ceramic body, and prepare silver electrodes by firing at 520℃ for 15 min; 8) The resistance value of the chip used to prepare the electrode is measured and the appearance is sorted to obtain the finished PTC thermistor. The Curie temperature of the finished product is 239℃ and the resistivity is 23Ω·cm.

[0032] Example 5: A formulation for a high Curie temperature, low resistivity PTC thermistor. Raw material composition and proportions: Composed of main materials, auxiliary materials, and sintering aids, based on 1 mol of TiO2. The molar composition of the main material is as follows: TiO2: 1 mol, BaCO3: 0.67 mol CaCO3: 0.05 mol SrCO3: 0 mol PbO: 0.28 mol; The molar composition of the auxiliary materials is as follows: Y2O3: 0.005 mol; The molar composition of the sintering aid is as follows: SiO2: 0.022 mol TiO2: 0.008 mol.

[0033] The above formula proposes a method for manufacturing high Curie temperature and low resistivity PTC thermistors. The steps include: 1) According to the required performance of the thermistor, weigh the raw materials according to the above raw material composition and proportion, and mix the weighed raw materials in a ball milling process according to the mass ratio of raw materials: grinding balls: deionized water = 1:2:2. 2) Dry the powder after one ball milling and pre-calcine it at 1060℃ for 3 hours; 3) The pre-calcined powder is ball-milled again according to the mass ratio of powder:grinding balls:deionized water = 1:2:2; 4) Dry the powder after the second ball milling, mix it thoroughly with the powder in a ratio of 100:17 (powder:13% polyvinyl alcohol solution), granulate it, and then dry it. 5) Press the powder into circular ceramic green bodies; the circular ceramic green bodies have a diameter of φ=6.15mm and a diameter of T=1.12mm; 6) The ceramic green body is loaded into the sintering sagger and rapidly sintered into a ceramic body at 1290℃ in a tunnel furnace for 50 minutes. 7) Print silver-zinc ohmic silver paste and surface silver paste on the front and back surfaces of the sintered ceramic body, and prepare silver electrodes by firing at 520℃ for 15 min; 8) The resistance value of the chip used to prepare the electrode is measured and the appearance is sorted to obtain the finished PTC thermistor. The Curie temperature of the finished product is 247℃ and the resistivity is 29Ω·cm.

[0034] Example 6: A formulation for a high Curie temperature, low resistivity PTC thermistor. Raw material composition and proportions: Composed of main materials, auxiliary materials, and sintering aids, based on 1 mol TiO2. The molar composition of the main material is as follows: TiO2: 1 mol, BaCO3: 0.65 mol CaCO3: 0.05 mol SrCO3: 0 mol PbO: 0.30 mol; The molar composition of the auxiliary materials is as follows: Y2O3: 0.005 mol; The molar composition of the sintering aid is as follows: SiO2: 0.022 mol TiO2: 0.008 mol.

[0035] The above formula proposes a method for manufacturing high Curie temperature and low resistivity PTC thermistors. The steps include: 1) According to the required performance of the thermistor, weigh the raw materials according to the above raw material composition and proportion, and mix the weighed raw materials in a ball milling process according to the mass ratio of raw materials: grinding balls: deionized water = 1:2:2. 2) Dry the powder after one ball milling and pre-calcine it at 1060℃ for 3 hours; 3) The pre-calcined powder is ball-milled again according to the mass ratio of powder:grinding balls:deionized water = 1:2:2; 4) Dry the powder after the second ball milling, mix it thoroughly with the powder in a ratio of 100:17 (powder:13% polyvinyl alcohol solution), granulate it, and then dry it. 5) Press the powder into circular ceramic green bodies; the circular ceramic green bodies have a diameter of φ=6.15mm and a diameter of T=1.12mm; 6) The ceramic green body is loaded into the sintering sagger and rapidly sintered into a ceramic body at 1290℃ in a tunnel furnace for 50 minutes. 7) Print silver-zinc ohmic silver paste and surface silver paste on the front and back surfaces of the sintered ceramic body, and prepare silver electrodes by firing at 520℃ for 15 min; 8) The resistance value of the chip used to prepare the electrode is measured and the appearance is sorted to obtain the finished PTC thermistor. The Curie temperature of the finished product is 255℃ and the resistivity is 35Ω·cm.

[0036] Example 7: A formulation for a high Curie temperature, low resistivity PTC thermistor. Raw material composition and proportions: Composed of main materials, auxiliary materials, and sintering aids, based on 1 mol TiO2. The molar composition of the main material is as follows: TiO2: 1 mol, BaCO3: 0.6 mol CaCO3: 0.10 mol SrCO3: 0.10 mol PbO: 0.20 mol; The molar composition of the auxiliary materials is as follows: Y2O3: 0.002 mol; The molar composition of the sintering aid is as follows: SiO2: 0.01 mol TiO2: 0.005 mol.

[0037] like Figure 1 As shown, a method for manufacturing a high Curie temperature and low resistivity PTC thermistor is proposed for the above formula. The steps include: 1) According to the required performance of the thermistor, weigh the raw materials according to the above raw material composition and proportion, and mix the weighed raw materials in a ball milling process according to the mass ratio of raw materials: grinding balls: deionized water = 1:2:2. 2) Dry the powder after one ball milling and pre-calcine it at 1070℃ for 3 hours; 3) The pre-calcined powder is ball-milled again according to the mass ratio of powder:grinding balls:deionized water = 1:2:2; 4) Dry the powder after the second ball milling, mix it thoroughly with the powder in a ratio of 100:17 (powder:13% polyvinyl alcohol solution), granulate it, and then dry it. 5) Press the powder into circular ceramic green bodies; the circular ceramic green bodies have a diameter of φ=6.15mm and a diameter of T=1.12mm; 6) The ceramic green body is loaded into a sintering sagger and rapidly sintered into a ceramic body at 1290℃ in a tunnel furnace; 7) Print silver-zinc ohmic silver paste and surface silver paste on the front and back surfaces of the sintered ceramic body, and prepare silver electrodes by firing at 520℃ for 15 min; 8) The resistance value of the chip used to prepare the electrode is measured and the appearance is sorted to obtain the finished PTC thermistor. The Curie temperature of the finished product is 215℃ and the resistivity is 21.3Ω·cm.

[0038] Example 8: A formulation for a high Curie temperature, low resistivity PTC thermistor. Raw material composition and proportions: Composed of main materials, auxiliary materials, and sintering aids, based on 1 mol of TiO2. The molar composition of the main material is as follows: TiO2: 1 mol, BaCO3: 0.72 mol CaCO3: 0.03 mol SrCO3: 0.07 mol PbO: 0.18 mol; The molar composition of the auxiliary materials is as follows: Y2O3: 0.01 mol; The molar composition of the sintering aid is as follows: SiO2: 0.04 mol TiO2: 0.015 mol.

[0039] The above formula proposes a method for manufacturing high Curie temperature and low resistivity PTC thermistors. The steps include: 1) According to the required performance of the thermistor, weigh the raw materials according to the above raw material composition and proportion, and mix the weighed raw materials in a ball milling process according to the mass ratio of raw materials: grinding balls: deionized water = 1:2:2. 2) Dry the powder after one ball milling and pre-calcine it at 1060℃ for 3 hours; 3) The pre-calcined powder is ball-milled again according to the mass ratio of powder:grinding balls:deionized water = 1:2:2; 4) Dry the powder after the second ball milling, mix it thoroughly with the powder in a ratio of 100:17 (powder:13% polyvinyl alcohol solution), granulate it, and then dry it. 5) Press the powder into circular ceramic green bodies; the circular ceramic green bodies have a diameter of φ=6.15mm and a diameter of T=1.12mm; 6) The ceramic green body is loaded into the sintering sagger and rapidly sintered into a ceramic body at 1280℃ in a tunnel furnace for 50 minutes. 7) Print silver-zinc ohmic silver paste and surface silver paste on the front and back surfaces of the sintered ceramic body, and prepare silver electrodes by firing at 520℃ for 15 min; 8) The resistance value of the electrode chip is measured and the appearance is sorted to obtain the finished PTC thermistor. The Curie temperature of the finished product is 207℃ and the resistivity is 19Ω·cm.

[0040] Example 9: A formulation for a high Curie temperature, low resistivity PTC thermistor. Raw material composition and proportions: Composed of main materials, auxiliary materials, and sintering aids, based on 1 mol TiO2. The molar composition of the main material is as follows: TiO2: 1 mol, BaCO3: 0.7 mol CaCO3: 0.08 mol SrCO3: 0.03 mol PbO: 0.19 mol; The molar composition of the auxiliary materials is as follows: Y2O3: 0.003 mol; The molar composition of the sintering aid is as follows: SiO2: 0.012 mol TiO2: 0.006 mol.

[0041] like Figure 1 As shown, a method for manufacturing a high Curie temperature and low resistivity PTC thermistor is proposed for the above formula. The steps include: 1) According to the required performance of the thermistor, weigh the raw materials according to the above raw material composition and proportion, and mix the weighed raw materials in a ball milling process according to the mass ratio of raw materials: grinding balls: deionized water = 1:2:2. 2) Dry the powder after one ball milling and pre-calcine it at 1070℃ for 3 hours; 3) The pre-calcined powder is ball-milled again according to the mass ratio of powder:grinding balls:deionized water = 1:2:2; 4) Dry the powder after the second ball milling, mix it thoroughly with the powder in a ratio of 100:17 (powder:13% polyvinyl alcohol solution), granulate it, and then dry it. 5) Press the powder into circular ceramic green bodies; the circular ceramic green bodies have a diameter of φ=6.15mm and a diameter of T=1.12mm; 6) The ceramic green body is loaded into a sintering sagger and rapidly sintered into a ceramic body at 1290℃ in a tunnel furnace; 7) Print silver-zinc ohmic silver paste and surface silver paste on the front and back surfaces of the sintered ceramic body, and prepare silver electrodes by firing at 520℃ for 15 min; 8) The resistance value of the electrode chip is measured and the appearance is sorted to obtain the finished PTC thermistor. The Curie temperature of the finished product is 211℃ and the resistivity is 20.1Ω·cm.

[0042] Example 10: A formulation for a high Curie temperature, low resistivity PTC thermistor. Raw material composition and proportions: Composed of main materials, auxiliary materials, and sintering aids, based on 1 mol of TiO2. The molar composition of the main material is as follows: TiO2: 1 mol, BaCO3: 0.60 mol CaCO3: 0.10 mol SrCO3: 0.07 mol PbO: 0.23 mol; The molar composition of the auxiliary materials is as follows: Y2O3: 0.009 mol; The molar composition of the sintering aid is as follows: SiO2: 0.035 mol TiO2: 0.012 mol.

[0043] The above formula proposes a method for manufacturing high Curie temperature and low resistivity PTC thermistors. The steps include: 1) According to the required performance of the thermistor, weigh the raw materials according to the above raw material composition and proportion, and mix the weighed raw materials in a ball milling process according to the mass ratio of raw materials: grinding balls: deionized water = 1:2:2. 2) Dry the powder after one ball milling and pre-calcine it at 1060℃ for 3 hours; 3) The pre-calcined powder is ball-milled again according to the mass ratio of powder:grinding balls:deionized water = 1:2:2; 4) Dry the powder after the second ball milling, mix it thoroughly with the powder in a ratio of 100:17 (powder:13% polyvinyl alcohol solution), granulate it, and then dry it. 5) Press the powder into circular ceramic green bodies; the circular ceramic green bodies have a diameter of φ=6.15mm and a diameter of T=1.12mm; 6) The ceramic green body is loaded into the sintering sagger and rapidly sintered into a ceramic body at 1290℃ in a tunnel furnace for 50 minutes. 7) Print silver-zinc ohmic silver paste and surface silver paste on the front and back surfaces of the sintered ceramic body, and prepare silver electrodes by firing at 520℃ for 15 min; 8) The resistance value of the electrode chip is measured and the appearance is sorted to obtain the finished PTC thermistor. The Curie temperature of the finished product is 227℃ and the resistivity is 24.7Ω·cm.

[0044] Example 11: A formulation for a high Curie temperature, low resistivity PTC thermistor. Raw material composition and proportions: Composed of main materials, auxiliary materials, and sintering aids, based on 1 mol TiO2. The molar composition of the main material is as follows: TiO2: 1 mol, BaCO3: 0.68 mol CaCO3: 0.07 mol SrCO3: 0.04 mol PbO: 0.21 mol; The molar composition of the auxiliary materials is as follows: Y2O3: 0.004 mol; The molar composition of the sintering aid is as follows: SiO2: 0.015 mol TiO2: 0.006 mol.

[0045] like Figure 1 As shown, a method for manufacturing a high Curie temperature and low resistivity PTC thermistor is proposed for the above formula. The steps include: 1) According to the required performance of the thermistor, weigh the raw materials according to the above raw material composition and proportion, and mix the weighed raw materials in a ball milling process according to the mass ratio of raw materials: grinding balls: deionized water = 1:2:2. 2) Dry the powder after one ball milling and pre-calcine it at 1070℃ for 3 hours; 3) The pre-calcined powder is ball-milled again according to the mass ratio of powder:grinding balls:deionized water = 1:2:2; 4) Dry the powder after the second ball milling, mix it thoroughly with the powder in a ratio of 100:17 (powder:13% polyvinyl alcohol solution), granulate it, and then dry it. 5) Press the powder into circular ceramic green bodies; the circular ceramic green bodies have a diameter of φ=6.15mm and a diameter of T=1.12mm; 6) The ceramic green body is loaded into a sintering sagger and rapidly sintered into a ceramic body at 1290℃ in a tunnel furnace; 7) Print silver-zinc ohmic silver paste and surface silver paste on the front and back surfaces of the sintered ceramic body, and prepare silver electrodes by firing at 520℃ for 15 min; 8) The resistance value of the electrode chip was measured and the appearance was sorted to obtain the finished PTC thermistor. The Curie temperature of the finished product was 219℃ and the resistivity was 22.4Ω·cm.

[0046] Example 12: A formulation for a high Curie temperature, low resistivity PTC thermistor. Raw material composition and proportions: Composed of main materials, auxiliary materials, and sintering aids, based on 1 mol of TiO2. The molar composition of the main material is as follows: TiO2: 1 mol, BaCO3: 0.63 mol CaCO3: 0.09 mol SrCO3: 0.06 mol PbO: 0.22 mol; The molar composition of the auxiliary materials is as follows: Y2O3: 0.006 mol; The molar composition of the sintering aid is as follows: SiO2: 0.030 mol TiO2: 0.010 mol.

[0047] The above formula proposes a method for manufacturing high Curie temperature and low resistivity PTC thermistors. The steps include: 1) According to the required performance of the thermistor, weigh the raw materials according to the above raw material composition and proportion, and mix the weighed raw materials in a ball milling process according to the mass ratio of raw materials: grinding balls: deionized water = 1:2:2. 2) Dry the powder after one ball milling and pre-calcine it at 1060℃ for 3 hours; 3) The pre-calcined powder is ball-milled again according to the mass ratio of powder:grinding balls:deionized water = 1:2:2; 4) Dry the powder after the second ball milling, mix it thoroughly with the powder in a ratio of 100:17 (powder:13% polyvinyl alcohol solution), granulate it, and then dry it. 5) Press the powder into circular ceramic green bodies; the circular ceramic green bodies have a diameter of φ=6.15mm and a diameter of T=1.12mm; 6) The ceramic green body is loaded into the sintering sagger and rapidly sintered into a ceramic body at 1290℃ in a tunnel furnace for 50 minutes. 7) Print silver-zinc ohmic silver paste and surface silver paste on the front and back surfaces of the sintered ceramic body, and prepare silver electrodes by firing at 520℃ for 15 min; 8) The resistance value of the electrode chip was measured and the appearance was sorted to obtain the finished PTC thermistor. The Curie temperature of the finished product was 223℃ and the resistivity was 23.6Ω·cm.

[0048] Example 13: A formulation for a high Curie temperature, low resistivity PTC thermistor. Raw material composition and proportions: Composed of main materials, auxiliary materials, and sintering aids, based on 1 mol TiO2. The molar composition of the main material is as follows: TiO2: 1 mol, BaCO3: 0.62 mol CaCO3: 0.06 mol SrCO3: 0.10 mol PbO: 0.22 mol; The molar composition of the auxiliary materials is as follows: Y2O3: 0.005 mol; The molar composition of the sintering aid is as follows: SiO2: 0.020 mol TiO2: 0.013 mol.

[0049] like Figure 1 As shown, a method for manufacturing a high Curie temperature and low resistivity PTC thermistor is proposed for the above formula. The steps include: 1) According to the required performance of the thermistor, weigh the raw materials according to the above raw material composition and proportion, and mix the weighed raw materials in a ball milling process according to the mass ratio of raw materials: grinding balls: deionized water = 1:2:2. 2) Dry the powder after one ball milling and pre-calcine it at 1070℃ for 3 hours; 3) The pre-calcined powder is ball-milled again according to the mass ratio of powder:grinding balls:deionized water = 1:2:2; 4) Dry the powder after the second ball milling, mix it thoroughly with the powder in a ratio of 100:17 (powder:13% polyvinyl alcohol solution), granulate it, and then dry it. 5) Press the powder into circular ceramic green bodies; the circular ceramic green bodies have a diameter of φ=6.15mm and a diameter of T=1.12mm; 6) The ceramic green body is loaded into a sintering sagger and rapidly sintered into a ceramic body at 1290℃ in a tunnel furnace; 7) Print silver-zinc ohmic silver paste and surface silver paste on the front and back surfaces of the sintered ceramic body, and prepare silver electrodes by firing at 520℃ for 15 min; 8) The resistance value of the electrode chip was measured and the appearance was sorted to obtain the finished PTC thermistor. The Curie temperature of the finished product was 223℃ and the resistivity was 23.6Ω·cm.

[0050] Example 14: A formulation for a high Curie temperature, low resistivity PTC thermistor. Raw material composition and proportions: Composed of main materials, auxiliary materials, and sintering aids, based on 1 mol of TiO2. The molar composition of the main material is as follows: TiO2: 1 mol, BaCO3: 0.61 mol CaCO3: 0.08 mol SrCO3: 0 mol PbO: 0.31 mol; The molar composition of the auxiliary materials is as follows: Y2O3: 0.005 mol; The molar composition of the sintering aid is as follows: SiO2: 0.022 mol TiO2: 0.008 mol.

[0051] The above formula proposes a method for manufacturing high Curie temperature and low resistivity PTC thermistors. The steps include: 1) According to the required performance of the thermistor, weigh the raw materials according to the above raw material composition and proportion, and mix the weighed raw materials in a ball milling process according to the mass ratio of raw materials: grinding balls: deionized water = 1:2:2. 2) Dry the powder after one ball milling and pre-calcine it at 1070℃ for 3 hours; 3) The pre-calcined powder is ball-milled again according to the mass ratio of powder:grinding balls:deionized water = 1:2:2; 4) Dry the powder after the second ball milling, mix it thoroughly with the powder in a ratio of 100:17 (powder:13% polyvinyl alcohol solution), granulate it, and then dry it. 5) Press the powder into circular ceramic green bodies; the circular ceramic green bodies have a diameter of φ=6.15mm and a diameter of T=1.12mm; 6) The ceramic green body is loaded into the sintering sagger and rapidly sintered into a ceramic body at 1280℃ in a tunnel furnace for 50 minutes. 7) Print silver-zinc ohmic silver paste and surface silver paste on the front and back surfaces of the sintered ceramic body, and prepare silver electrodes by firing at 520℃ for 15 min; 8) The resistance value of the chip used to prepare the electrode is measured and the appearance is sorted to obtain the finished PTC thermistor. The Curie temperature of the finished product is 259℃ and the resistivity is 33.9Ω·cm.

[0052] Example 15: A formulation for a high Curie temperature, low resistivity PTC thermistor. Raw material composition and proportions: Composed of main materials, auxiliary materials, and sintering aids, based on 1 mol TiO2. The molar composition of the main material is as follows: TiO2: 1 mol, BaCO3: 0.71 mol CaCO3: 0.03 mol SrCO3: 0 mol PbO: 0.26 mol; The molar composition of the auxiliary materials is as follows: Y2O3: 0.003 mol; The molar composition of the sintering aid is as follows: SiO2: 0.012 mol TiO2: 0.006 mol.

[0053] like Figure 1As shown, a method for manufacturing a high Curie temperature and low resistivity PTC thermistor is proposed for the above formula. The steps include: 1) According to the required performance of the thermistor, weigh the raw materials according to the above raw material composition and proportion, and mix the weighed raw materials in a ball milling process according to the mass ratio of raw materials: grinding balls: deionized water = 1:2:2. 2) Dry the powder after one ball milling and pre-calcine it at 1070℃ for 3 hours; 3) The pre-calcined powder is ball-milled again according to the mass ratio of powder:grinding balls:deionized water = 1:2:2; 4) Dry the powder after the second ball milling, mix it thoroughly with the powder in a ratio of 100:17 (powder:13% polyvinyl alcohol solution), granulate it, and then dry it. 5) Press the powder into circular ceramic green bodies; the circular ceramic green bodies have a diameter of φ=6.15mm and a diameter of T=1.12mm; 6) The ceramic green body is loaded into a sintering sagger and rapidly sintered into a ceramic body at 1290℃ in a tunnel furnace; 7) Print silver-zinc ohmic silver paste and surface silver paste on the front and back surfaces of the sintered ceramic body, and prepare silver electrodes by firing at 520℃ for 15 min; 8) The resistance value of the electrode chip was measured and the appearance was sorted to obtain the finished PTC thermistor. The Curie temperature of the finished product was 239℃ and the resistivity was 28.1Ω·cm.

[0054] Example 16: A formulation for a high Curie temperature, low resistivity PTC thermistor. Raw material composition and proportions: Composed of main materials, auxiliary materials, and sintering aids, based on 1 mol of TiO2. The molar composition of the main material is as follows: TiO2: 1 mol, BaCO3: 0.62 mol CaCO3: 0.08 mol SrCO3: 0 mol PbO: 0.30 mol; The molar composition of the auxiliary materials is as follows: Y2O3: 0.009 mol; The molar composition of the sintering aid is as follows: SiO2: 0.035 mol TiO2: 0.012 mol.

[0055] The above formula proposes a method for manufacturing high Curie temperature and low resistivity PTC thermistors. The steps include: 1) According to the required performance of the thermistor, weigh the raw materials according to the above raw material composition and proportion, and mix the weighed raw materials in a ball milling process according to the mass ratio of raw materials: grinding balls: deionized water = 1:2:2. 2) Dry the powder after one ball milling and pre-calcine it at 1080℃ for 3 hours; 3) The pre-calcined powder is ball-milled again according to the mass ratio of powder:grinding balls:deionized water = 1:2:2; 4) Dry the powder after the second ball milling, mix it thoroughly with the powder in a ratio of 100:17 (powder:13% polyvinyl alcohol solution), granulate it, and then dry it. 5) Press the powder into circular ceramic green bodies; the circular ceramic green bodies have a diameter of φ=6.15mm and a diameter of T=1.12mm; 6) The ceramic green body is loaded into a sintering sagger and rapidly sintered into a ceramic body at 1270℃ in a tunnel furnace for 50 minutes. 7) Print silver-zinc ohmic silver paste and surface silver paste on the front and back surfaces of the sintered ceramic body, and prepare silver electrodes by firing at 520℃ for 15 min; 8) The resistance value of the chip used to prepare the electrode is measured and the appearance is sorted to obtain the finished PTC thermistor. The Curie temperature of the finished product is 255℃ and the resistivity is 32.7Ω·cm.

[0056] Example 17: A formulation for a high Curie temperature, low resistivity PTC thermistor. Raw material composition and proportions: Composed of main materials, auxiliary materials, and sintering aids, based on 1 mol TiO2. The molar composition of the main material is as follows: TiO2: 1 mol, BaCO3: 0.69 mol CaCO3: 0.04 mol SrCO3: 0 mol PbO: 0.27 mol; The molar composition of the auxiliary materials is as follows: Y2O3: 0.004 mol; The molar composition of the sintering aid is as follows: SiO2: 0.015 mol TiO2: 0.006 mol.

[0057] like Figure 1As shown, a method for manufacturing a high Curie temperature and low resistivity PTC thermistor is proposed for the above formula. The steps include: 1) According to the required performance of the thermistor, weigh the raw materials according to the above raw material composition and proportion, and mix the weighed raw materials in a ball milling process according to the mass ratio of raw materials: grinding balls: deionized water = 1:2:2. 2) Dry the powder after one ball milling and pre-calcine it at 1070℃ for 3 hours; 3) The pre-calcined powder is ball-milled again according to the mass ratio of powder:grinding balls:deionized water = 1:2:2; 4) Dry the powder after the second ball milling, mix it thoroughly with the powder in a ratio of 100:17 (powder:13% polyvinyl alcohol solution), granulate it, and then dry it. 5) Press the powder into circular ceramic green bodies; the circular ceramic green bodies have a diameter of φ=6.15mm and a diameter of T=1.12mm; 6) The ceramic green body is loaded into a sintering sagger and rapidly sintered into a ceramic body at 1290℃ in a tunnel furnace; 7) Print silver-zinc ohmic silver paste and surface silver paste on the front and back surfaces of the sintered ceramic body, and prepare silver electrodes by firing at 520℃ for 15 min; 8) The resistance value of the chip used to prepare the electrode is measured and the appearance is sorted to obtain the finished PTC thermistor. The Curie temperature of the finished product is 243℃ and the resistivity is 29.3Ω·cm.

[0058] Example 18: A formulation for a high Curie temperature, low resistivity PTC thermistor. Raw material composition and proportions: Composed of main materials, auxiliary materials, and sintering aids, based on 1 mol of TiO2. The molar composition of the main material is as follows: TiO2: 1 mol, BaCO3: 0.65 mol CaCO3: 0.06 mol SrCO3: 0 mol PbO: 0.29 mol; The molar composition of the auxiliary materials is as follows: Y2O3: 0.006 mol; The molar composition of the sintering aid is as follows: SiO2: 0.030 mol TiO2: 0.010 mol.

[0059] The above formula proposes a method for manufacturing high Curie temperature and low resistivity PTC thermistors. The steps include: 1) According to the required performance of the thermistor, weigh the raw materials according to the above raw material composition and proportion, and mix the weighed raw materials in a ball milling process according to the mass ratio of raw materials: grinding balls: deionized water = 1:2:2. 2) Dry the powder after one ball milling and pre-calcine it at 1060℃ for 3 hours; 3) The pre-calcined powder is ball-milled again according to the mass ratio of powder:grinding balls:deionized water = 1:2:2; 4) Dry the powder after the second ball milling, mix it thoroughly with the powder in a ratio of 100:17 (powder:13% polyvinyl alcohol solution), granulate it, and then dry it. 5) Press the powder into circular ceramic green bodies; the circular ceramic green bodies have a diameter of φ=6.15mm and a diameter of T=1.12mm; 6) The ceramic green body is loaded into the sintering sagger and rapidly sintered into a ceramic body at 1290℃ in a tunnel furnace for 50 minutes. 7) Print silver-zinc ohmic silver paste and surface silver paste on the front and back surfaces of the sintered ceramic body, and prepare silver electrodes by firing at 520℃ for 15 min; 8) The resistance value of the electrode chip is measured and the appearance is sorted to obtain the finished PTC thermistor. The Curie temperature of the finished product is 251℃ and the resistivity is 31.6Ω·cm.

[0060] Example 19: A formulation for a high Curie temperature, low resistivity PTC thermistor. Raw material composition and proportions: Composed of main materials, auxiliary materials, and sintering aids, based on 1 mol TiO2. The molar composition of the main material is as follows: TiO2: 1 mol, BaCO3: 0.70 mol CaCO3: 0.07 mol SrCO3: 0 mol PbO: 0.23 mol; The molar composition of the auxiliary materials is as follows: Y2O3: 0.005 mol; The molar composition of the sintering aid is as follows: SiO2: 0.025 mol TiO2: 0.008 mol.

[0061] like Figure 1As shown, a method for manufacturing a high Curie temperature and low resistivity PTC thermistor is proposed for the above formula. The steps include: 1) According to the required performance of the thermistor, weigh the raw materials according to the above raw material composition and proportion, and mix the weighed raw materials in a ball milling process according to the mass ratio of raw materials: grinding balls: deionized water = 1:2:2. 2) Dry the powder after one ball milling and pre-calcine it at 1070℃ for 3 hours; 3) The pre-calcined powder is ball-milled again according to the mass ratio of powder:grinding balls:deionized water = 1:2:2; 4) Dry the powder after the second ball milling, mix it thoroughly with the powder in a ratio of 100:17 (powder:13% polyvinyl alcohol solution), granulate it, and then dry it. 5) Press the powder into circular ceramic green bodies; the circular ceramic green bodies have a diameter of φ=6.15mm and a diameter of T=1.12mm; 6) The ceramic green body is loaded into a sintering sagger and rapidly sintered into a ceramic body at 1290℃ in a tunnel furnace; 7) Print silver-zinc ohmic silver paste and surface silver paste on the front and back surfaces of the sintered ceramic body, and prepare silver electrodes by firing at 520℃ for 15 min; 8) The resistance value of the electrode chip is measured and the appearance is sorted to obtain the finished PTC thermistor. The Curie temperature of the finished product is 227℃ and the resistivity is 24.7Ω·cm.

[0062] Example 20: A formulation for a high Curie temperature, low resistivity PTC thermistor. Raw material composition and proportions: Composed of main materials, auxiliary materials, and sintering aids, based on 1 mol of TiO2. The molar composition of the main material is as follows: TiO2: 1 mol, BaCO3: 0.64 mol CaCO3: 0.05 mol SrCO3: 0 mol PbO: 0.31 mol; The molar composition of the auxiliary materials is as follows: Y2O3: 0.007 mol; The molar composition of the sintering aid is as follows: SiO2: 0.020 mol TiO2: 0.011 mol.

[0063] The above formula proposes a method for manufacturing high Curie temperature and low resistivity PTC thermistors. The steps include: 1) According to the required performance of the thermistor, weigh the raw materials according to the above raw material composition and proportion, and mix the weighed raw materials in a ball milling process according to the mass ratio of raw materials: grinding balls: deionized water = 1:2:2. 2) Dry the powder after one ball milling and pre-calcine it at 1070℃ for 3 hours; 3) The pre-calcined powder is ball-milled again according to the mass ratio of powder:grinding balls:deionized water = 1:2:2; 4) Dry the powder after the second ball milling, mix it thoroughly with the powder in a ratio of 100:17 (powder:13% polyvinyl alcohol solution), granulate it, and then dry it. 5) Press the powder into circular ceramic green bodies; the circular ceramic green bodies have a diameter of φ=6.15mm and a diameter of T=1.12mm; 6) The ceramic green body is loaded into a sintering sagger and rapidly sintered into a ceramic body at 1270℃ in a tunnel furnace for 50 minutes. 7) Print silver-zinc ohmic silver paste and surface silver paste on the front and back surfaces of the sintered ceramic body, and prepare silver electrodes by firing at 520℃ for 15 min; 8) The resistance value of the chip used to prepare the electrode is measured and the appearance is sorted to obtain the finished PTC thermistor. The Curie temperature of the finished product is 259℃ and the resistivity is 33.9Ω·cm.

[0064] The above are merely preferred embodiments of the present invention. It should be noted that the above preferred embodiments should not be considered as limitations on the present invention, and the scope of protection of the present invention should be determined by the scope defined in the claims. For those skilled in the art, several improvements and modifications can be made without departing from the spirit and scope of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A high Curie temperature, low resistivity PTC thermistor formulation, characterized in that, The thermistor has a Curie temperature of 200~260℃ and a resistivity of 15~40Ω·cm. Its raw material composition and proportions consist of main materials, auxiliary materials, and sintering aids, based on 1 mol of TiO2. The molar composition of the main material is as follows: TiO2: 1 mol, BaCO3: 0.60~0.72 mol, CaCO3: 0.03~0.10 mol, SrCO3: 0~0.10 mol, PbO: 0.18~0.31 mol; The molar composition of the auxiliary materials is as follows: Y₂O₃: 0.002~0.010 mol; The molar composition of the sintering aid is as follows: SiO2: 0.010~0.040 mol TiO2: 0.005~0.015 mol; The above formula can be used to prepare the thermistor according to the following process steps: 1) Weigh the raw materials according to the required performance of the thermistor, the composition and proportion of the raw materials, and mix the weighed raw materials in a mass ratio of raw materials: grinding balls: deionized water = 1:2:

2. 2) Dry the powder after one ball milling and pre-calcine it at 1050~1100℃ for 3 hours; 3) The pre-calcined powder is ball-milled again according to the mass ratio of powder:grinding balls:deionized water = 1:2:2; 4) Dry the powder after the second ball milling, mix it thoroughly with the powder in a ratio of 100:17 (powder:13% polyvinyl alcohol solution), granulate it, and then dry it. 5) Press the powder into circular ceramic green bodies; 6) The ceramic green body is loaded into a sintering sagger and rapidly sintered into a ceramic body in a tunnel furnace at 1280~1300℃; 7) Print silver-zinc ohmic silver paste and surface silver paste on the front and back surfaces of the sintered ceramic body, and prepare silver electrodes by firing at 520℃ for 10~20 min; 8) The resistance value of the chip used to prepare the electrode is measured and the appearance is sorted to obtain the finished PTC thermistor.

2. The high Curie temperature, low resistivity PTC thermistor formulation according to claim 1, characterized in that, For a Curie temperature of 200℃, the raw material composition and proportions are as follows: The molar composition of the main material is as follows: TiO2: 1 mol, BaCO3: 0.60~0.70 mol CaCO3: 0.06~0.10 mol, SrCO3: 0.03~0.07 mol, PbO: 0.19~0.23 mol; The molar composition of the auxiliary materials is as follows: Y₂O₃: 0.003~0.009 mol; The molar composition of the sintering aid is as follows: SiO2: 0.012~0.035 mol TiO2: 0.006~0.012 mol.

3. The high Curie temperature, low resistivity PTC thermistor formulation according to claim 2, characterized in that, For a Curie temperature of 200℃, the raw material composition and proportions are as follows: The molar composition of the main material is as follows: TiO2: 1 mol, BaCO3: 0.62~0.68 mol CaCO3: 0.07~0.09 mol, SrCO3: 0.04~0.06 mol, PbO: 0.20~0.22 mol; The molar composition of the auxiliary materials is as follows: Y₂O₃: 0.004~0.006 mol; The molar composition of the sintering aid is as follows: SiO2: 0.015~0.030 mol TiO2: 0.006~0.010 mol.

4. The high Curie temperature, low resistivity PTC thermistor formulation according to claim 1, characterized in that, For a Curie temperature of 260℃, the raw material composition and proportions are as follows: The molar composition of the main material is as follows: TiO2: 1 mol, BaCO3: 0.62~0.72 mol, CaCO3: 0.03~0.07 mol, PbO: 0.26~0.30 mol; The molar composition of the auxiliary materials is as follows: Y₂O₃: 0.003~0.009 mol; The molar composition of the sintering aid is as follows: SiO2: 0.012~0.035 mol TiO2: 0.006~0.012 mol.

5. The high Curie temperature, low resistivity PTC thermistor formulation according to claim 4, characterized in that, For a Curie temperature of 260℃, the raw material composition and proportions are as follows: The molar composition of the main material is as follows: TiO2: 1 mol, BaCO3: 0.64~0.70 mol CaCO3: 0.04~0.06 mol, PbO: 0.27~0.29 mol; The molar composition of the auxiliary materials is as follows: Y₂O₃: 0.004~0.006 mol; The molar composition of the sintering aid is as follows: SiO2: 0.015~0.030 mol TiO2: 0.006~0.010 mol.

6. A method for manufacturing a high Curie temperature, low resistivity PTC thermistor, characterized in that, The steps include: 1) Weighing raw materials according to the required performance of the thermistor, based on the raw material composition and proportions described in any one of claims 1-5, and ball milling the weighed raw materials once according to the mass ratio of raw materials: grinding balls: deionized water = 1:2:2; 2) Dry the powder after one ball milling and pre-calcine it at 1050~1100℃ for 3 hours; 3) The pre-calcined powder is ball-milled again according to the mass ratio of powder:grinding balls:deionized water = 1:2:2; 4) Dry the powder after the second ball milling, mix it thoroughly with the powder in a ratio of 100:17 (powder:13% polyvinyl alcohol solution), granulate it, and then dry it. 5) Press the powder into circular ceramic green bodies; 6) The ceramic green body is loaded into a sintering sagger and rapidly sintered into a ceramic body in a tunnel furnace at 1280~1300℃; 7) Print silver-zinc ohmic silver paste and surface silver paste on the front and back surfaces of the sintered ceramic body, and prepare silver electrodes by firing at 520℃ for 10~20 min; 8) The resistance value of the chip used to prepare the electrode is measured and the appearance is sorted to obtain the finished PTC thermistor.

7. The method for manufacturing a high Curie temperature, low resistivity PTC thermistor according to claim 6, characterized in that, In step 5), the circular ceramic green body has a diameter of φ=6.15mm and a diameter of T=1.12mm.

8. A high Curie temperature, low resistivity PTC thermistor, characterized in that, Made by the method described in any one of claims 6-7.

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