A method for manufacturing a thermistor material

Abstract

The application discloses a kind of thermistor material production methods, comprising the following steps: after Mn3O4, NiO, Co3O4, modified Al2O3, Fe2O3, polyvinyl pyrrolidone are mixed, first ball mill is obtained in ball mill;First ball mill is placed in tube furnace, under inert gas atmosphere, after heating to 950~1000 DEG C calcination 2.0~2.5h, after cooling, calcined powder is obtained;Second ball mill is obtained by placing calcined powder into ball mill;Second ball mill, 2,5-furandimethanol, casein are mixed and placed into forming mold and pressed into green compact;Green compact is placed into muffle furnace, first calcined at 750~800 DEG C for 1.0~1.5h, then heated to 1100~1150 DEG C and calcined for 2.5~3h to obtain thermistor material.The application mixes Al2O3, MgO, La2O3 uniformly in proportion, then places them in plasma equipment for processing and vacuum calcination to obtain modified Al2O3, which is added to thermistor material, thereby improving the sensitivity and stability of thermistor material, and having wide application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of thermistors, and in particular to a method for manufacturing a thermistor material. Background Art

[0002] Thermistor materials are materials whose resistance changes significantly with temperature. Based on their temperature coefficient characteristics, they can be divided into negative temperature coefficient (NTC) thermistor materials and positive temperature coefficient (PTC) thermistor materials. NTC thermistor materials, whose resistance decreases as temperature increases, are primarily used in temperature sensors for air conditioners, refrigerators, and automobiles, as well as surge suppressors for power supplies or motors. PTC thermistor materials, whose resistance increases with temperature, are primarily used for USB port protection, lithium battery overcharge protection, and heating elements in thermostatic heaters.

[0003] With the rapid development of the deep-sea, aerospace, medical, and smart car industries, the demand for sensitive components in sensing and control systems with high precision and the ability to withstand harsh environments continues to grow, leading to an increasing number of applications for materials in extreme environments. Negative temperature coefficient thermistor materials, with their advantages of small size, high sensitivity, and low cost, are widely used in temperature measurement and control, overcurrent protection for electronic products, and temperature compensation.

[0004] Currently, negative temperature coefficient (NTC) thermistor materials on the market are mainly made of manganese (Mn), cobalt (Co), and nickel (Ni) oxides as the main raw materials through mixing, grinding, and sintering processes. However, they generally have problems such as poor sensitivity and low stability, and are prone to aging under high temperature conditions, which affects the performance of the thermistor materials.

[0005] Therefore, there is an urgent need for a method for manufacturing a thermistor material to solve the problems of low sensitivity, easy aging and poor stability of negative temperature coefficient thermistor materials. Summary of the Invention

[0006] The object of the present invention is to provide a method for manufacturing a thermistor material to solve the problems of low sensitivity, easy aging and poor stability of negative temperature coefficient thermistor materials mentioned in the above background technology.

[0007] To achieve the above object, the present invention provides the following technical solution: a method for manufacturing a thermistor material, comprising the following steps:

[0008] S1. Mix 40 to 50 parts by weight of Mn3O4, 20 to 25 parts by weight of NiO, 10 to 15 parts by weight of Co3O4, 7 to 10 parts by weight of modified Al2O3, 3 to 5 parts by weight of Fe2O3, and 1.5 to 2 parts by weight of polyvinyl pyrrolidone, and place the mixture in a ball mill for ball milling to obtain the first ball mill material.

[0009] S2. Place the first ball mill prepared in S1 in a tubular furnace, heat it to 950-1000°C at a heating rate of 5°C / min under an inert gas atmosphere, and calcine it for 2.0-2.5h. After cooling, obtain a calcined powder.

[0010] S3. Place the calcined powder obtained in S2 into a ball mill and ball-mill to obtain a second ball-milled material.

[0011] S4. The second ball mill, 2,5-furan dimethanol, and casein are evenly mixed and placed into a molding die for pressing to obtain a green sheet.

[0012] S5. Place the green sheet in a muffle furnace and calcine it at 750-800°C for 1.0-1.5 hours, then raise the temperature to 1100-1150°C and calcine it for 2.5-3 hours to obtain the thermistor material.

[0013] As a preferred technical solution of the present invention, the modified Al2O3 is prepared by the following method: 25 to 30 parts by weight of Al2O3, 10 to 12 parts by weight of MgO, and 5 to 8 parts by weight of La2O3 are mixed evenly and placed in a plasma device for treatment for 25 to 30 minutes; the plasma-treated mixture is calcined at 300 to 350°C and a vacuum degree of 0.005 to 0.01 Pa for 2.5 to 3 hours and then cooled to obtain modified Al2O3.

[0014] As a preferred technical solution of the present invention, the rotation speed of the ball mill is 110-120 rpm, the mesh size of the first ball mill is 500 mesh, and the mesh size of the second ball mill is 600 mesh.

[0015] As a preferred technical solution of the present invention, the inert gas is nitrogen or argon, and the standard concentration of nitrogen or argon is 99.99%.

[0016] As a preferred technical solution of the present invention, the addition amount of the 2,5-furan dimethanol is 0.8-1.2% of the mass of the second ball mill; the addition amount of the casein is 0.5-0.8% of the mass of the second ball mill.

[0017] As a preferred technical solution of the present invention, the diameter of the forming die is 5 mm; the pressure during the pressing process is 250-270 MPa, and the pressing time is 120-130 s.

[0018] As a preferred technical solution of the present invention, the charge density of the plasma equipment is 1600-1700 C / cm 3 , gas flow rate is 2.0~2.2L / min, processing chamber pressure is 110~120kPa, and processing chamber temperature is 50~55℃.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. The present invention incorporates modified Al2O3 during the preparation of NTC thermistor materials, improving the thermistor material's anti-aging properties and high-temperature stability. Furthermore, during the ball milling process, the addition of modified Al2O3 can refine the grains, increase the material's density and uniformity, and thus improve the thermistor's stability. Mixed doping with MgO, La2O3, and Al2O3 can adjust the resistivity of the NTC thermistor material and optimize the material constant B value, thereby increasing its temperature sensitivity and enhancing the stability of the NTC thermistor material in high-temperature environments. MgO has a high melting point and excellent thermal stability, preventing the NTC thermistor material from undergoing phase transitions or decomposition at high temperatures. La2O3, as a rare earth oxide, can enhance the material's lattice stability and reduce performance degradation at high temperatures. Doping with MgO and La2O3 can refine the NTC thermistor material's grain structure, reduce grain boundary defects, and improve the material's density and mechanical strength. Modified Al2O3 improves the material's high-temperature, moisture, and chemical resistance, enabling it to maintain stable performance even in harsh environments. This reduces performance degradation during long-term use and extends the lifespan of NTC thermistors. Plasma treatment activates the surfaces of MgO, La2O3, and Al2O3, promoting their uniform dispersion within the NTC thermistor material. This strengthens the interfacial bonding between MgO, La2O3, and Al2O3, reduces interfacial defects, improves doping efficiency, and enhances the material's overall performance. During vacuum calcination, the addition of MgO and La2O3 promotes phase transformation and crystallization in the NTC thermistor material, forming a stable crystal structure. Furthermore, the plasma-modified mixture of Al2O3, MgO, and La2O3, followed by calcination, eliminates residual stress within the material, reducing performance fluctuations during the thermistor's operation.

[0021] 2. During the preparation of the thermistor material, the present invention adds 2,5-furan dimethanol, casein, and a ball-milled base, mixes them evenly, and then presses them into shape and calcines them. The hydroxyl groups (-OH) in the 2,5-furan dimethanol can form complexes with metal salt precursors, improving particle dispersibility, enabling better mixing and dispersion of the components in the thermistor material and enhancing the uniformity of the raw materials. Furthermore, the alcoholic hydroxyl groups in the 2,5-furan dimethanol structure are nucleophilic and can react chemically with metal ions during calcination, forming specific chemical bonds and improving the performance of the thermistor. Furthermore, the hydroxyl groups in the 2,5-furan dimethanol can bind to the surfaces of ceramic particles such as Mn3O4 and NiO, reducing interfacial defects, lowering resistivity, and improving stability. Furthermore, the 2,5-furan dimethanol acts as a sintering aid during calcination, lowering the sintering temperature, improving the density of the sintered body, and enhancing the stability and reliability of the thermistor. Casein acts as a binder to bond the oxide particles together to form a green body with a certain strength, which is convenient for calcination and processing. Casein will decompose or burn at high temperatures, leaving pores. These pores can adjust the porosity and specific surface area of ​​the thermistor material and improve the response speed of the thermistor material. The carboxyl group (-COOH) in casein can react with Mn 2+ 、Ni 2+ Combined, a more uniform precursor distribution is formed before sintering, which reduces high-temperature phase separation and improves the consistency of B value.

[0022] 3. The present invention adopts a method of calcining the thermistor green sheet at a low temperature followed by a high temperature. During the low temperature stage, the binder in the green sheet volatilizes slowly, avoiding cracking, deformation, or increased internal porosity in the green sheet caused by rapid volatilization. The slow volatilization of the binder allows the green sheet to maintain a relatively dense and uniform structure, reducing internal stress and defects caused by rapid volatilization, thereby improving the yield and stability of the thermistor material. At the same time, the low temperature calcination facilitates the initial formation and arrangement of grains in the green sheet, promoting their orderly growth and reducing grain boundary defects. During the high temperature stage, the grains further grow and crystallize, forming a more complete crystal structure, thereby reducing resistivity and increasing the temperature coefficient B value. In addition, the low temperature followed by high temperature calcination process helps ensure uniform heating of the green sheet during the calcination process, reduces performance differences caused by temperature gradients, and improves the consistency and stability of the thermistor material. Furthermore, the low temperature followed by high temperature calcination process can fully utilize the heat in the low temperature stage, reduce energy consumption in the high temperature stage, and reduce production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a flow chart for preparing thermistor of the present invention. DETAILED DESCRIPTION

[0024] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0025] like Figure 1 As shown, a method for preparing a thermistor material includes the following steps: S1. (1) Preparation of modified Al2O3: Al2O3, MgO, and La2O3 are mixed uniformly in proportion and then placed in a plasma device for treatment for 25 to 30 minutes; the mixture after plasma treatment is calcined at 300 to 350°C under vacuum conditions for 2.5 to 3 hours and then cooled to obtain modified Al2O3; (2) Ball milling of raw materials: Mn3O4, NiO, Co3O4, modified Al2O3, Fe2O3, and polyvinyl pyrrolidone are mixed in proportion and then placed in a ball mill for ball milling to obtain the first ball milling material; S2. A ball mill material is placed in a tube furnace, and in an inert gas atmosphere, the temperature is increased to 950-1000° C. at a heating rate of 5° C. / min, and then calcined for 2.0-2.5 hours. After cooling, a calcined powder is obtained; S3. The calcined powder is placed in a ball mill and ball-milled to obtain a second ball mill material; S4. The second ball mill material, 2,5-furan dimethanol, and casein are uniformly mixed and placed in a forming mold for pressing to obtain a green sheet; S5. The green sheet is placed in a muffle furnace and first calcined at 750-800° C. for 1.0-1.5 hours, and then the temperature is increased to 1100-1150° C. and calcined for 2.5-3 hours to obtain a thermistor material.

[0026] The raw materials used in the present invention are all commercially available raw materials.

[0027] Example 1:

[0028] A method for preparing a thermistor material is prepared by the following method:

[0029] S1. (1) Preparation of modified Al2O3: 25 parts by weight of Al2O3, 10 parts by weight of MgO, and 5 parts by weight of La2O3 were mixed evenly and placed in a plasma device (the charge density of the plasma device was 1600 C / cm 3, gas flow rate of 2.0L / min, treatment chamber pressure of 110kPa, treatment chamber temperature of 50℃) for 30min; the mixture after plasma treatment was calcined at 300℃ and vacuum degree of 0.005Pa for 3h and then cooled to obtain modified Al2O3. (2) Ball milling of raw materials: 40 parts by weight of Mn3O4, 20 parts by weight of NiO, 10 parts by weight of Co3O4, 7 parts by weight of modified Al2O3, 3 parts by weight of Fe2O3, and 1.5 parts by weight of polyvinyl pyrrolidone were mixed and placed in a ball mill (ball mill speed of 110rpm) for ball milling to obtain the first ball mill material with a mesh size of 500 mesh.

[0030] S2. The first ball mill prepared in S1 was placed in a tubular furnace. Under a nitrogen atmosphere, the temperature was raised to 950°C at a heating rate of 5°C / min, and then calcined for 2.5 h. After cooling, a calcined powder was obtained.

[0031] S3. The calcined powder obtained in S2 is placed in a ball mill and ball-milled to obtain a second ball-milled material with a mesh size of 600 mesh.

[0032] S4. The second mill material, 2,5-furan dimethanol (added in an amount of 0.8% by mass of the second mill material), and casein (added in an amount of 0.5% by mass of the second mill material) were mixed evenly and placed into a molding die with a diameter of 5 mm. The mixture was pressed at a pressure of 250 MPa for 130 seconds to obtain a green sheet.

[0033] S5. Place the green sheet in a muffle furnace and calcine it at 750°C for 1.5 hours, then raise the temperature to 1100°C and calcine it for 3 hours to obtain the thermistor material.

[0034] Example 2:

[0035] A method for preparing a thermistor material is prepared by the following method:

[0036] S1. (1) Preparation of modified Al2O3: 30 parts by weight of Al2O3, 12 parts by weight of MgO, and 8 parts by weight of La2O3 were mixed and placed in a plasma device (the charge density of the plasma device was 1700 C / cm 3 , gas flow rate of 2.2 L / min, treatment chamber pressure of 120 kPa, treatment chamber temperature of 55 ° C) for 25 min; the mixture after plasma treatment was calcined at 350 ° C and vacuum degree of 0.01 Pa for 2.5 h and then cooled to obtain modified Al2O3. (2) Raw material ball milling: 50 parts by weight of Mn3O4, 25 parts by weight of NiO, 15 parts by weight of Co3O4, 10 parts by weight of modified Al2O3, 5 parts by weight of Fe2O3, and 2 parts by weight of polyvinyl pyrrolidone were mixed and placed in a ball mill (ball mill speed of 120 rpm) for ball milling to obtain a first ball mill material with a mesh size of 500 mesh.

[0037] S2. Place the first ball mill prepared in S1 in a tubular furnace, heat it to 1000°C at a heating rate of 5°C / min under a nitrogen atmosphere, and calcine it for 2.0 h. After cooling, obtain a calcined powder.

[0038] S3. The calcined powder obtained in S2 is placed in a ball mill and ball-milled to obtain a second ball-milled material with a mesh size of 600 mesh.

[0039] S4. The second mill material, 2,5-furan dimethanol (added in an amount of 1.2% by mass of the second mill material), and casein (added in an amount of 0.8% by mass of the second mill material) were mixed evenly and placed into a molding die with a diameter of 5 mm. The mixture was pressed at a pressure of 270 MPa for 120 seconds to obtain a green sheet.

[0040] S5. Place the green sheet in a muffle furnace and calcine it at 800°C for 1.0 h, then raise the temperature to 1150°C and calcine it for 2.5 h to obtain the thermistor material.

[0041] Example 3:

[0042] A method for preparing a thermistor material is prepared by the following method:

[0043] S1. (1) Preparation of modified Al2O3: 28 parts by weight of Al2O3, 11 parts by weight of MgO, and 6 parts by weight of La2O3 were mixed and placed in a plasma device (the charge density of the plasma device was 1650 C / cm 3 , gas flow rate of 2.1L / min, treatment chamber pressure of 115kPa, treatment chamber temperature of 52℃) for 27min; the mixture after plasma treatment was calcined at 320℃ and vacuum degree of 0.008Pa for 2.5h and then cooled to obtain modified Al2O3. (2) Ball milling of raw materials: 45 parts by weight of Mn3O4, 22 parts by weight of NiO, 12 parts by weight of Co3O4, 7-10 parts by weight of modified Al2O3, 4 parts by weight of Fe2O3, and 2 parts by weight of polyvinyl pyrrolidone were mixed and placed in a ball mill (ball mill speed of 150rpm) for ball milling to obtain a first ball mill material with a mesh size of 500 mesh.

[0044] S2. The first ball mill prepared in S1 was placed in a tubular furnace. Under an argon atmosphere, the temperature was raised to 980°C at a heating rate of 5°C / min, and then calcined for 2.0 h. After cooling, a calcined powder was obtained.

[0045] S3. The calcined powder obtained in S2 is placed in a ball mill and ball-milled to obtain a second ball-milled material with a mesh size of 600 mesh.

[0046] S4. The second mill material, 2,5-furan dimethanol (added in an amount of 1.0% by mass of the second mill material), and casein (added in an amount of 0.6% by mass of the second mill material) were mixed evenly and placed into a molding die with a diameter of 5 mm. The mixture was pressed at a pressure of 260 MPa for 125 seconds to obtain a green sheet.

[0047] S5. Place the green sheet in a muffle furnace and calcine it at 760°C for 1.0 h, then raise the temperature to 1120°C and calcine it for 3 h to obtain the thermistor material.

[0048] Comparative Example 1:

[0049] The difference from Example 1 is that modified Al2O3 is not added.

[0050] Comparative Example 2:

[0051] The difference from Example 1 is that Al2O3 is added directly without modification.

[0052] Comparative Example 3:

[0053] The difference from Example 1 is that the modified Al2O3 is not treated by plasma equipment.

[0054] Comparative Example 4:

[0055] The difference from Example 1 is that the modified Al2O3 is not calcined.

[0056] Comparative Example 5:

[0057] The difference from Example 1 is that 2,5-furan dimethanol is not added.

[0058] Comparative Example 6:

[0059] The difference from Example 1 is that no casein is added.

[0060] Comparative Example 7:

[0061] The difference from Example 1 is that S5 is changed to: placing the green sheet in a muffle furnace and calcining it at 750° C. for 4.5 hours to obtain the thermistor material.

[0062] Comparative Example 8:

[0063] The difference from Example 1 is that S5 is changed to: placing the green sheet in a muffle furnace and calcining it at 1100° C. for 4.5 hours to obtain the thermistor material.

[0064] The thermistor materials prepared in Examples 1, 2, 3 and Comparative Examples 1, 2, 3, 4, 5, 6, 7, and 8 were made into NTC thermistors and their performance was tested.

[0065] Using a resistance tester, the resistance value was measured at -25℃ and 200℃, and the material constant B value of the thermistor was calculated; the zero-power resistance at room temperature (25℃) was measured, and the resistivity was calculated.

[0066] The NTC thermistor was placed at a temperature of 120°C for 20 days and 50 days, and its resistance at a temperature of 25°C was tested.

[0067] As shown in Table 1, the B constants of the thermistors in the examples are all high, and the resistivity is low at 25°C. The B constant reflects the rate at which the resistance value changes with temperature. The larger the B constant, the faster the resistance value changes with temperature, and the more sensitive the thermistor is to temperature changes. Materials with high resistivity are more susceptible to factors such as humidity, temperature, and pollution, which lead to changes in resistance and affect the stability of the material. Modified Al2O3 improves the aging resistance and high-temperature stability of the thermistor material. During the ball milling process, the addition of modified Al2O3 can refine the grains, increase the density and uniformity of the material, and thus improve the stability of the thermistor. Mixed doping with MgO, La2O3, and Al2O3 can adjust the resistivity of the NTC thermistor material and optimize the material constant B value, thereby improving its temperature sensitivity and enhancing the stability of the NTC thermistor material in high-temperature environments. Plasma treatment activates the surfaces of MgO, La2O3, and Al2O3, promoting their uniform dispersion within the NTC thermistor material. This enhances the interfacial bonding between these three groups, reduces interfacial defects, improves doping efficiency, and enhances the overall performance of the material. During vacuum calcination, the doping of MgO and La2O3 promotes phase transformation and crystallization in the NTC thermistor material, forming a stable crystal structure. Furthermore, plasma treatment and subsequent calcination of the mixed Al2O3, MgO, and La2O3 eliminate residual stress within the material, reducing performance fluctuations during operation and improving the sensitivity and stability of the thermistor material. The hydroxyl groups in the 2,5-furan dimethanol structure are nucleophilic and react chemically with metal ions during calcination, forming specific chemical bonds that enhance the thermistor's performance. Furthermore, the hydroxyl groups in 2,5-furan dimethanol can bond with the surfaces of ceramic particles such as Mn3O4 and NiO, reducing interfacial defects, lowering resistivity, and improving stability. Casein decomposes or burns at high temperatures, leaving behind pores. These pores can adjust the porosity and specific surface area of ​​the thermistor material, improving its response speed and, consequently, sensitivity. Calcining at low temperatures followed by high temperatures reduces internal stress and defects caused by rapid volatilization at high temperatures, thereby improving the yield and stability of the thermistor material. Low-temperature calcination also promotes the initial formation and arrangement of grains in the green sheet, promoting their orderly growth and reducing grain boundary defects. During the high-temperature stage, the grains further grow and crystallize, forming a more complete crystal structure, thereby reducing resistivity and increasing the temperature coefficient (B).

[0068] Table 1: NTC thermistor performance test table

[0069]

[0070] As shown in Table 2, the resistance before placement is the initial resistance of the thermistor. After the thermistor is placed at 120°C for 20 days, the resistance change rate of the embodiment is between 0.38% and 0.53%, while the resistance change rate of the control ratio is between 1.39% and 3.59%; after the thermistor is placed at 120°C for 50 days, the resistance change rate of the embodiment is between 2.09% and 2.59%, while the resistance change rate of the control ratio is between 7.13% and 17.55%. After modification, Al2O3 can improve the material's high temperature resistance, moisture resistance and chemical resistance, so that it can still maintain stable performance in harsh environments, delay its aging and increase its service life. 2,5-Furan dimethanol acts as a sintering aid during the calcination process, reducing the sintering temperature, improving the density of the sintered body, and improving the stability of the thermistor. The carboxyl group (-COOH) in casein can react with Mn 2+ 、Ni 2+ Combined with the above, a more uniform precursor distribution is formed before sintering, which reduces high-temperature phase separation, improves the consistency of B value, and delays resistor aging. Sintering at low temperature first and then at high temperature can improve the yield and stability of thermistor materials.

[0071] Table 2: Resistance change of thermistor after storage at 120℃

[0072]

[0073] In summary, the thermistor prepared by the present invention has high sensitivity, strong stability, is not easy to age, and has broad application prospects.

[0074] The above are only specific embodiments of the present invention, but the technical features of the present invention are not limited thereto. Any simple changes, equivalent substitutions, or modifications based on the present invention to solve substantially the same technical problems and achieve substantially the same technical effects are all included in the scope of protection of the present invention.

Claims

1. A method for manufacturing a thermistor material, characterized in that: The following steps are involved: S1. 40 to 50 parts by weight of Mn3O4, 20 to 25 parts by weight of NiO, 10 to 15 parts by weight of Co3O4, 7 to 10 parts by weight of modified Al2O3, 3 to 5 parts by weight of Fe2O3, 1.5 to 2 parts by weight of polyvinylpyrrolidone were mixed and placed in a ball mill to obtain a first ball mill; S2. The first ball mill prepared in S1 was placed in a tube furnace and heated to 950-1000°C at a heating rate of 5°C / min under an inert gas atmosphere and calcined for 2.0-2.5h. The calcined powder was obtained after cooling. S3. The calcined powder obtained in S2 was placed in a ball mill to obtain a second ball mill; S4. The second ball mill, 2,5-furan dimethanol, and casein were mixed and then placed in a molding mold for compression molding to obtain a green sheet; S5. The green sheet is placed in a muffle furnace and calcined at 750-800 ° C for 1.0-1.5 h, then heated to 1100-1150 ° C and calcined for 2.5-3 h to obtain a thermistor material; The modified Al2O3 is prepared by the following method: 25 to 30 parts by weight of Al2O3, 10 to 12 parts by weight of MgO, and 5 to 8 parts by weight of La2O3 are uniformly mixed and then placed in a plasma device for treatment for 25 to 30 minutes; the plasma-treated mixture is calcined at 300 to 350° C. under vacuum conditions for 2.5 to 3 hours and then cooled to obtain the modified Al2O3.

2. The method for manufacturing a thermistor material according to claim 1, wherein: The rotation speed of the ball mill is 110-120 rpm, the mesh number of the first ball mill is 500 mesh, and the mesh number of the second ball mill is 600 mesh.

3. The method for manufacturing a thermistor material according to claim 1, wherein: The inert gas is nitrogen or argon, and the standard concentration of nitrogen or argon is 99.99%.

4. The method for manufacturing a thermistor material according to claim 1, wherein: The added amount of the 2,5-furan dimethanol is 0.8-1.2% of the mass of the second ball mill; the added amount of the casein is 0.5-0.8% of the mass of the second ball mill.

5. The method for manufacturing a thermistor material according to claim 1, wherein: The diameter of the forming die is 5 mm; the pressure during the pressing process is 250-270 MPa, and the pressing time is 120-130 s.

6. The method for manufacturing a thermistor material according to claim 1, wherein: The charge density of the plasma equipment is 1600-1700 C / cm 3 , gas flow rate is 2.0~2.2L / min, processing chamber pressure is 110~120kPa, and processing chamber temperature is 50~55℃.

7. The method for manufacturing a thermistor material according to claim 1, wherein: The vacuum degree under the vacuum conditions is 0.005-0.01 Pa.

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