High-precision NTC thermistor and preparation method thereof

Abstract

The invention discloses a high-precision NTC (Negative Temperature Coefficient) thermistor and a preparation method thereof, relates to the technical field of NTC thermistors, and is characterized in that the structural stability is improved through a cocktail effect; the high configuration entropy reduces the Gibbs free energy change of lattice deformation, inhibits lattice distortion at a high temperature, greatly expands the temperature range of the prepared NTC thermistor, and further improves the anti-aging performance of the NTC thermistor in a high-temperature environment, greatly reduces the resistance drift rate in the high-temperature environment, and widens the application range of the NTC thermistor in combination with multiple protection mechanisms.

Description

Technical Field

[0001] This invention relates to the field of NTC thermistor technology, specifically a high-precision NTC thermistor and its preparation method. Background Technology

[0002] In the rapid development of modern industry and technology, many fields have placed stringent demands on precise temperature measurement and control. Especially in industries such as metallurgy, special processing, automotive, and aerospace, the need for precise measurement and control of temperatures above 1000℃ is becoming increasingly prominent as technology continues to upgrade. Negative temperature coefficient (NTC) thermistors, due to their advantages such as high sensitivity, fast response, simple structure, and low cost, have become a highly promising high-temperature sensor solution and have attracted much attention.

[0003] The core component of an NTC thermistor is the NTC thermistor ceramic, whose resistivity decreases exponentially with increasing temperature. Common NTC thermistor ceramics are mostly spinel or other oxide ceramics, often containing one or more transition metal oxides such as CoO, NiO, and MnO. Depending on the chemical composition, the operating temperature range of NTC thermistors varies. High-temperature NTC thermistor ceramics generally operate in the range of 300-1000℃, with common examples being ZrO2-Y2O3 and ZrO2-CaO fluorite-type structural materials.

[0004] However, current high-temperature NTC thermistors face numerous challenges in practical applications and performance improvement. On the one hand, for thermistors to be stable in the ultra-wide temperature range of 25-1300℃ for a long time, the NTC thermistor ceramic needs to possess both high resistivity and a suitable material constant (B) value at high temperatures. However, there is a positive correlation between resistivity and B value, and achieving synergistic reverse regulation of the two has become a research challenge in the field of NTC thermistor ceramics. On the other hand, when the operating temperature rises, especially above 1000℃, traditional high-temperature NTC thermistor ceramics struggle to maintain stable performance due to changes in the conductivity mechanism and severe distortion of the crystal structure, exhibiting poor high-temperature aging characteristics. For example, common NTC thermistors made by sintering metal oxides such as manganese, chromium, iron, and copper are prone to decomposition of metal oxides in high-temperature environments, limiting their maximum operating temperature, and even at slightly lower temperatures, irreversible changes may occur.

[0005] Therefore, it is of great significance to invent a high-precision NTC thermistor for use in high-temperature environments. Summary of the Invention

[0006] The purpose of this invention is to provide a high-precision NTC thermistor and its preparation method to solve the problems raised in the prior art.

[0007] To achieve the above objectives, the present invention provides the following technical solution: A high-precision NTC thermistor, comprising, from bottom to top, a substrate layer, a sensitive layer, a protective layer, and a sandwich protective layer; the substrate layer is alumina; the sensitive layer is prepared by printing rare earth-based chromate paste; the protective layer is prepared by printing chromium oxide paste; the sandwich protective layer includes an alumina sol layer and a glass-ceramic glaze layer.

[0008] Furthermore, the preparation method of the rare earth-based chromate slurry includes the following steps: La2O3, Nd2O3, Sm2O3, Eu2O3, Gd2O3, and Cr2O3 were added to a ball mill jar and ball-milled for 8-10 hours with ethanol as the dispersant to obtain a slurry. The slurry was then vacuum-dried at 100-105℃, ground, heated to 1100-1105℃ for pre-sintering for 5-5.5 hours, and ground again to obtain a precursor powder. The precursor powder was then added to polysilazane, stirred evenly, and ultrasonically dispersed to obtain a rare earth-based chromate slurry.

[0009] Furthermore, in the preparation process of the precursor powder, the molar ratio of La:Nd:Sm:Eu:Gd:Cr is 1:1:1:1:1:5; in the preparation process of the rare earth-based chromate slurry, the mass ratio of precursor powder to polysilazane is (1-2):(3-4); and the particle size of the precursor powder is 3-5μm.

[0010] Furthermore, the method for preparing the chromium oxide slurry includes the following steps: Chromium oxide was added to polysilazane, stirred evenly, and ultrasonically dispersed to obtain chromium oxide slurry.

[0011] Furthermore, in the preparation process of chromium oxide slurry, the mass ratio of chromium oxide to polysilazane is 1:(1.5-2); the particle size of the chromium oxide is 1-1.5μm.

[0012] Furthermore, the thickness of the sensitive layer is 20-25 μm; the thickness of the protective layer is 20-25 μm; the thickness of the sandwich protective layer is 60 μm; the thickness of the alumina sol layer is 15-20 μm; and the thickness of the glass-ceramic glaze layer is 20-30 μm.

[0013] A method for preparing a high-precision NTC thermistor includes the following steps: printing a rare-earth-based chromate paste onto the surface of a substrate layer, sintering it at 1550-1555℃ for 15-16 hours to obtain a sensitive layer; after cooling, printing a chromium oxide paste onto the surface of the sensitive layer, annealing it at 1300-1305℃ for 1-1.5 hours to obtain a protective layer; after cooling, spraying an alumina sol onto the surface of the protective layer, annealing it at 1100-1105℃ for 1-1.5 hours to obtain an alumina sol layer; after cooling, spraying a glass-ceramic glaze onto the surface of the alumina sol layer, annealing it at 1200-1205℃ for 0.5-1 hours to obtain a glass-ceramic glaze layer; after cooling, spraying an alumina sol onto the surface of the glass-ceramic glaze layer, annealing it at 1100-1105℃ for 1-1.5 hours, cooling, and obtaining a high-precision NTC thermistor by attaching a silver-palladium electrode and platinum wire leads.

[0014] Furthermore, the glass-ceramic glaze has a solid content of 10-40 wt%, with the remainder being deionized water.

[0015] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention enhances structural stability through the "cocktail effect"; high configurational entropy reduces the Gibbs free energy change of lattice deformation, suppresses lattice distortion at high temperatures, and further improves its anti-aging performance in high-temperature environments, greatly reducing the resistance drift rate in high-temperature environments and broadening the application range of NTC thermistors.

[0016] 2. The sensitive layer prepared by this invention differs from traditional chromate ceramics in that its Cr-O bond length phrases LaCrO3 and YCrO3 have stronger bond energies, reducing Cr content. 3+ To Cr 4+ Oxidation of CrO 6 Octahedral distortion and CrO3 volatilization significantly reduce porosity and improve density, laying the foundation for stable operation in high-temperature environments.

[0017] 3. In order to further improve the stability of NTC thermistors at high temperatures, this invention uses polysilazane in the slurry to transform into SiOC ceramic under high temperature conditions, filling the gaps in the sensitive layer and further stabilizing the structure. At the same time, the chromium oxide protective layer can further inhibit the decomposition of sensitive layer particles and the overflow of chromium oxide at high temperatures, reducing material degradation at high temperatures.

[0018] 4. Furthermore, this invention utilizes a sandwich protective layer based on the design principle of "soft and hard combination". It leverages the self-healing and barrier function of the middle glass-ceramic glaze layer and the structural support and isolation function of the upper and lower ceramic layers. The three-layer structure is tightly integrated without obvious gaps. The densification of the glass layer blocks gas diffusion and material migration, while the stability of the ceramic layer solves the problem of volatilization and corrosion of the glass layer at high temperatures. Together, they inhibit the oxidation, sublimation and structural damage of the sensitive material, ultimately enabling the sensor to operate stably in high-temperature environments above 1300℃.

[0019] The glass-ceramic glaze melts at high temperatures, filling the pores and microcracks within the protective layer to form a dense, continuous structure. This prevents oxygen from diffusing inwards and the sublimation products of the sensitive material from escaping outwards, reducing oxidation and sublimation loss of the sensitive layer. Simultaneously, its stable crystalline and amorphous phases ensure structural stability at high temperatures, functioning as a self-healing and sealing agent for the "soft" component. The high-melting-point alumina ceramic, as the "hard" component, provides structural support and thermal stability for the entire protective layer, preventing the intermediate glass layer from being lost due to volatilization at high temperatures. The bottom layer isolates the sensitive film from the molten glass, preventing the sensitive layer from being eroded by the glaze; the top layer reduces high-temperature volatilization of the glass layer while enhancing the overall mechanical strength and wear resistance of the protective layer. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of a high-precision NTC thermistor according to the present invention; The layers are: 1. Substrate layer; 2. Sensitive layer; 3. Protective layer; 4. Sandwich protective layer; 5. Alumina sol layer; 6. Glass-ceramic glaze layer. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Example 1: A method for preparing a high-precision NTC thermistor, comprising the following steps: S1: La2O3, Nd2O3, Sm2O3, Eu2O3, Gd2O3, and Cr2O3 are added to a ball mill jar, and ethanol is used as a dispersant. The mixture is ball-milled for 8 hours to obtain a slurry. The slurry is then vacuum-dried at 100°C, ground, heated to 1100°C for pre-sintering for 5 hours, and ground again to obtain a precursor powder. The precursor powder is added to polysilazane, stirred evenly, and ultrasonically dispersed to obtain a rare earth-based chromate slurry.

[0023] In the preparation of the precursor powder, the molar ratio of La:Nd:Sm:Eu:Gd:Cr is 1:1:1:1:1:5; in the preparation of the rare earth-based chromate slurry, the mass ratio of precursor powder to polysilazane is 1:3; and the particle size of the precursor powder is 3 μm.

[0024] S2: Add chromium oxide to polysilazane, stir evenly, and ultrasonically disperse to obtain chromium oxide slurry.

[0025] In the preparation of chromium oxide slurry, the mass ratio of chromium oxide to polysilazane is 1:1.5; the particle size of the chromium oxide is 1 μm.

[0026] S3: A rare earth-based chromate paste is printed on the surface of the substrate layer 1 and sintered at 1550℃ for 15 hours to obtain the sensitive layer 2. After cooling, a chromium oxide paste is printed on the surface of the sensitive layer 2 and annealed at 1300℃ for 1 hour to obtain the protective layer 3. After cooling, an alumina sol is sprayed onto the surface of the protective layer 3 and annealed at 1100℃ for 1 hour to obtain the alumina sol layer 5. After cooling, a glass ceramic glaze is sprayed onto the surface of the alumina sol layer 5 and annealed at 1200℃ for 0.5 hours to obtain the glass ceramic glaze layer 6. After cooling, an alumina sol is sprayed onto the surface of the glass ceramic glaze layer 6 and annealed at 1100℃ for 1 hour. After cooling, a high-precision NTC thermistor is obtained by attaching silver-palladium electrodes and platinum wire leads. The thickness of the sensitive layer is 20 μm; the thickness of the protective layer is 25 μm; the thickness of the alumina sol layer is 15 μm; and the thickness of the glass-ceramic glaze layer is 30 μm.

[0027] Example 2: A method for preparing a high-precision NTC thermistor, comprising the following steps: S1: La2O3, Nd2O3, Sm2O3, Eu2O3, Gd2O3, and Cr2O3 are added to a ball mill jar, and ethanol is used as a dispersant. The mixture is ball-milled for 8 hours to obtain a slurry. The slurry is then vacuum-dried at 100°C, ground, heated to 1100°C for pre-sintering for 5 hours, and ground again to obtain a precursor powder. The precursor powder is added to polysilazane, stirred evenly, and ultrasonically dispersed to obtain a rare earth-based chromate slurry.

[0028] In the preparation of the precursor powder, the molar ratio of La:Nd:Sm:Eu:Gd:Cr is 1:1:1:1:1:5; in the preparation of the rare earth-based chromate slurry, the mass ratio of precursor powder to polysilazane is 2:4; and the particle size of the precursor powder is 3 μm.

[0029] S2: Add chromium oxide to polysilazane, stir evenly, and ultrasonically disperse to obtain chromium oxide slurry.

[0030] In the preparation of chromium oxide slurry, the mass ratio of chromium oxide to polysilazane is 1:1.5; the particle size of the chromium oxide is 1 μm.

[0031] S3: A rare earth-based chromate paste is printed on the surface of the substrate layer 1 and sintered at 1550℃ for 15 hours to obtain the sensitive layer 2. After cooling, a chromium oxide paste is printed on the surface of the sensitive layer 2 and annealed at 1300℃ for 1 hour to obtain the protective layer 3. After cooling, an alumina sol is sprayed onto the surface of the protective layer 3 and annealed at 1100℃ for 1 hour to obtain the alumina sol layer 5. After cooling, a glass ceramic glaze is sprayed onto the surface of the alumina sol layer 5 and annealed at 1200℃ for 0.5 hours to obtain the glass ceramic glaze layer 6. After cooling, an alumina sol is sprayed onto the surface of the glass ceramic glaze layer 6 and annealed at 1100℃ for 1 hour. After cooling, a high-precision NTC thermistor is obtained by attaching silver-palladium electrodes and platinum wire leads. The thickness of the sensitive layer is 20 μm; the thickness of the protective layer is 25 μm; the thickness of the alumina sol layer is 15 μm; and the thickness of the glass-ceramic glaze layer is 30 μm. Comparative Example 1: A method for preparing a high-precision NTC thermistor, comprising the following steps: S1: ; 0.6MgAl2O4-0.4LaCr 0.5 Mn 0.5 O3 precursor powder was added to polysilazane, stirred evenly, and ultrasonically dispersed to obtain rare earth-based chromate slurry.

[0032] In the preparation of the rare earth-based chromate slurry, the mass ratio of precursor powder to polysilazane is 1:3; the particle size of the precursor powder is 3μm.

[0033] S2: Add chromium oxide to polysilazane, stir evenly, and ultrasonically disperse to obtain chromium oxide slurry.

[0034] In the preparation of chromium oxide slurry, the mass ratio of chromium oxide to polysilazane is 1:1.5; the particle size of the chromium oxide is 1 μm.

[0035] S3: A rare earth-based chromate paste is printed on the surface of the substrate layer 1 and sintered at 1550℃ for 15 hours to obtain the sensitive layer 2. After cooling, a chromium oxide paste is printed on the surface of the sensitive layer 2 and annealed at 1300℃ for 1 hour to obtain the protective layer 3. After cooling, an alumina sol is sprayed onto the surface of the protective layer 3 and annealed at 1100℃ for 1 hour to obtain the alumina sol layer 5. After cooling, a glass ceramic glaze is sprayed onto the surface of the alumina sol layer 5 and annealed at 1200℃ for 0.5 hours to obtain the glass ceramic glaze layer 6. After cooling, an alumina sol is sprayed onto the surface of the glass ceramic glaze layer 6 and annealed at 1100℃ for 1 hour. After cooling, a high-precision NTC thermistor is obtained by attaching silver-palladium electrodes and platinum wire leads. The thickness of the sensitive layer is 20 μm; the thickness of the protective layer is 20 μm; the thickness of the alumina sol layer is 15 μm; and the thickness of the glass-ceramic glaze layer is 30 μm.

[0036] Comparative Example 2: A method for preparing a high-precision NTC thermistor, comprising the following steps: S1: ; YCr 0.5 Mn 0.5 O3 precursor powder was added to polysilazane, stirred evenly, and ultrasonically dispersed to obtain rare earth-based chromate slurry.

[0037] In the preparation of the rare earth-based chromate slurry, the mass ratio of precursor powder to polysilazane is 1:3; the particle size of the precursor powder is 3μm.

[0038] S2: Add chromium oxide to polysilazane, stir evenly, and ultrasonically disperse to obtain chromium oxide slurry.

[0039] In the preparation of chromium oxide slurry, the mass ratio of chromium oxide to polysilazane is 1:1.5; the particle size of the chromium oxide is 1 μm.

[0040] S3: A rare earth-based chromate paste is printed on the surface of the substrate layer 1 and sintered at 1550℃ for 15 hours to obtain the sensitive layer 2. After cooling, a chromium oxide paste is printed on the surface of the sensitive layer 2 and annealed at 1300℃ for 1 hour to obtain the protective layer 3. After cooling, an alumina sol is sprayed onto the surface of the protective layer 3 and annealed at 1100℃ for 1 hour to obtain the alumina sol layer 5. After cooling, a glass ceramic glaze is sprayed onto the surface of the alumina sol layer 5 and annealed at 1200℃ for 0.5 hours to obtain the glass ceramic glaze layer 6. After cooling, an alumina sol is sprayed onto the surface of the glass ceramic glaze layer 6 and annealed at 1100℃ for 1 hour. After cooling, a high-precision NTC thermistor is obtained by attaching silver-palladium electrodes and platinum wire leads. The thickness of the sensitive layer is 20 μm; the thickness of the protective layer is 20 μm; the thickness of the alumina sol layer is 15 μm; and the thickness of the glass-ceramic glaze layer is 30 μm.

[0041] Comparative Example 3: A method for preparing a high-precision NTC thermistor, comprising the following steps: S1: Add YCrO3 precursor powder to polysilazane, stir evenly, and ultrasonically disperse to obtain rare earth-based chromate slurry.

[0042] In the preparation of the rare earth-based chromate slurry, the mass ratio of precursor powder to polysilazane is 1:3; the particle size of the precursor powder is 3μm.

[0043] S2: Add chromium oxide to polysilazane, stir evenly, and ultrasonically disperse to obtain chromium oxide slurry.

[0044] In the preparation of chromium oxide slurry, the mass ratio of chromium oxide to polysilazane is 1:1.5; the particle size of the chromium oxide is 1 μm.

[0045] S3: A rare earth-based chromate paste is printed on the surface of the substrate layer 1 and sintered at 1550℃ for 15 hours to obtain the sensitive layer 2. After cooling, a chromium oxide paste is printed on the surface of the sensitive layer 2 and annealed at 1300℃ for 1 hour to obtain the protective layer 3. After cooling, an alumina sol is sprayed onto the surface of the protective layer 3 and annealed at 1100℃ for 1 hour to obtain the alumina sol layer 5. After cooling, a glass ceramic glaze is sprayed onto the surface of the alumina sol layer 5 and annealed at 1200℃ for 0.5 hours to obtain the glass ceramic glaze layer 6. After cooling, an alumina sol is sprayed onto the surface of the glass ceramic glaze layer 6 and annealed at 1100℃ for 1 hour. After cooling, a high-precision NTC thermistor is obtained by attaching silver-palladium electrodes and platinum wire leads. The thickness of the sensitive layer is 20 μm; the thickness of the protective layer is 20 μm; the thickness of the alumina sol layer is 15 μm; and the thickness of the glass-ceramic glaze layer is 30 μm.

[0046] Comparative Example 4: A method for preparing a high-precision NTC thermistor, comprising the following steps: S1: La2O3, Nd2O3, Sm2O3, Eu2O3, Gd2O3, and Cr2O3 are added to a ball mill jar, and ethanol is used as a dispersant. The mixture is ball-milled for 8 hours to obtain a slurry. The slurry is then vacuum-dried at 100°C, ground, heated to 1100°C for pre-sintering for 5 hours, and ground again to obtain a precursor powder. The precursor powder is added to polysilazane, stirred evenly, and ultrasonically dispersed to obtain a rare earth-based chromate slurry.

[0047] In the preparation of the precursor powder, the molar ratio of La:Nd:Sm:Eu:Gd:Cr is 1:1:1:1:1:5; in the preparation of the rare earth-based chromate slurry, the mass ratio of precursor powder to polysilazane is 1:3; and the particle size of the precursor powder is 3 μm.

[0048] S2: Rare earth-based chromate paste is printed on the surface of substrate layer 1 and sintered at 1550℃ for 15 hours to obtain sensitive layer 2; after cooling, alumina sol is sprayed onto the surface of sensitive layer 2 and annealed at 1100℃ for 1 hour to obtain alumina sol layer 5; after cooling, glass ceramic glaze is sprayed onto the surface of alumina sol layer 5 and annealed at 1200℃ for 0.5 hours to obtain glass ceramic glaze layer 6; after cooling, alumina sol is sprayed onto the surface of glass ceramic glaze layer 6 and annealed at 1100℃ for 1 hour, and then cooled. By attaching silver-palladium electrodes and platinum wire leads, a high-precision NTC thermistor is obtained. The thickness of the sensitive layer is 20 μm; the thickness of the protective layer is 25 μm; the thickness of the alumina sol layer is 15 μm; and the thickness of the glass-ceramic glaze layer is 30 μm.

[0049] Comparative Example 5: A method for preparing a high-precision NTC thermistor, comprising the following steps: S1: La2O3, Nd2O3, Sm2O3, Eu2O3, Gd2O3, and Cr2O3 are added to a ball mill jar, and ethanol is used as a dispersant. The mixture is ball-milled for 8 hours to obtain a slurry. The slurry is then vacuum-dried at 100°C, ground, heated to 1100°C for pre-sintering for 5 hours, and ground again to obtain a precursor powder. The precursor powder is added to polysilazane, stirred evenly, and ultrasonically dispersed to obtain a rare earth-based chromate slurry.

[0050] In the preparation of the precursor powder, the molar ratio of La:Nd:Sm:Eu:Gd:Cr is 1:1:1:1:1:5; in the preparation of the rare earth-based chromate slurry, the mass ratio of precursor powder to polysilazane is 1:3; and the particle size of the precursor powder is 3 μm.

[0051] S2: Add chromium oxide to polysilazane, stir evenly, and ultrasonically disperse to obtain chromium oxide slurry.

[0052] In the preparation of chromium oxide slurry, the mass ratio of chromium oxide to polysilazane is 1:1.5; the particle size of the chromium oxide is 1 μm.

[0053] S3: Print rare earth-based chromate paste on the surface of substrate layer 1, heat to 1550℃ and sinter for 15 hours to obtain sensitive layer 2; after cooling, print chromium oxide paste on the surface of sensitive layer 2, heat to 1300℃ and anneal for 1 hour to obtain protective layer 3; after cooling, obtain high-precision NTC thermistor by attaching silver palladium electrodes and platinum wire leads. The thickness of the sensitive layer is 20 μm; the thickness of the protective layer is 25 μm. Experiment: Resistance drift test: Electrode aging test was carried out in a high-temperature tube furnace at a temperature of 1300℃; During the aging process, the resistance drift rate of the sample was monitored over time until the aging time reached 1000 hours, and finally the resistance drift data of the material after 1000 hours at 1300℃ was obtained. Adhesion test: A scratch tester was used to perform a scratch test, and the load was gradually applied. The friction force and acoustic emission signals were recorded to determine the critical load of the coating, thereby evaluating the adhesion strength between the film and the substrate after annealing at 1300℃.

[0054] The experimental data are shown in Table 1 below.

[0055] Table 1 Performance Test Data of High-Precision NTC Thermistors Resistance drift rate / % Adhesion strength / N Example 1 4.12(1300℃) 39.6 Example 2 3.99(1300℃) 41.2 Comparative Example 1 70(1000℃) / Comparative Example 2 20(1000℃) / Comparative Example 3 40(1000℃) / Comparative Example 4 6.78(1300℃) 16.9 Comparative Example 5 7.12(1300℃) 36.2 Conclusion: The NTC thermistor prepared by this invention can work for a long time in a high-temperature environment of 1300℃, which greatly expands the application range of NTC thermistors.

[0056] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A high-precision NTC thermistor, characterized in that: The NTC thermistor is composed of a substrate layer (1), a sensitive layer (2), a protective layer (3), and a sandwich protective layer (4) from bottom to top. The substrate layer (1) is alumina. The sensitive layer (2) is prepared by printing rare earth-based chromate paste. The protective layer (3) is prepared by printing chromium oxide paste. The sandwich protective layer (4) includes an alumina sol layer (5) and a glass ceramic glaze layer (6).

2. The high-precision NTC thermistor according to claim 1, characterized in that: The method for preparing the rare earth-based chromate slurry includes the following steps: La2O3, Nd2O3, Sm2O3, Eu2O3, Gd2O3, and Cr2O3 were added to a ball mill jar and ball-milled for 8-10 hours with ethanol as the dispersant to obtain a slurry. The slurry was then vacuum-dried at 100-105℃, ground, heated to 1100-1105℃ for pre-sintering for 5-5.5 hours, and ground again to obtain a precursor powder. The precursor powder was then added to polysilazane, stirred evenly, and ultrasonically dispersed to obtain a rare earth-based chromate slurry.

3. A high-precision NTC thermistor according to claim 2, characterized in that: In the preparation of the precursor powder, the molar ratio of La:Nd:Sm:Eu:Gd:Cr is 1:1:1:1:1:5; in the preparation of the rare earth-based chromate slurry, the mass ratio of precursor powder to polysilazane is (1-2):(3-4); the particle size of the precursor powder is 3-5μm.

4. A high-precision NTC thermistor according to claim 1, characterized in that: The method for preparing the chromium oxide slurry includes the following steps: Chromium oxide was added to polysilazane, stirred evenly, and ultrasonically dispersed to obtain chromium oxide slurry.

5. A high-precision NTC thermistor according to claim 4, characterized in that: In the preparation of chromium oxide slurry, the mass ratio of chromium oxide to polysilazane is 1:(1.5-2); the particle size of the chromium oxide is 1-1.5μm.

6. A high-precision NTC thermistor according to claim 1, characterized in that: The thickness of the sensitive layer (2) is 20-25 μm; the thickness of the protective layer (3) is 20-25 μm; the thickness of the sandwich protective layer (4) is 60 μm; the thickness of the alumina sol layer (5) is 15-20 μm; and the thickness of the glass ceramic glaze layer (6) is 20-30 μm.

7. A method for preparing a high-precision NTC thermistor according to any one of claims 1-6, characterized in that: Includes the following steps: Rare earth-based chromate paste was printed onto the surface of the substrate layer (1), and sintered at 1550-1555℃ for 15-16 hours to obtain the sensitive layer (2). After cooling, chromium oxide paste was printed onto the surface of the sensitive layer (2), and annealed at 1300-1305℃ for 1-1.5 hours to obtain the protective layer (3). After cooling, alumina sol was sprayed onto the surface of the protective layer (3), and annealed at 1100-1105℃ for 1-1.5 hours to obtain the... Alumina sol layer (5) is formed; after cooling, glass ceramic glaze is sprayed onto the surface of alumina sol layer (5), heated to 1200-1205℃ and annealed for 0.5-1h to obtain glass ceramic glaze layer (6); after cooling, alumina sol is sprayed onto the surface of glass ceramic glaze layer (6), heated to 1100-1105℃ and annealed for 1-1.5h, cooled, and high-precision NTC thermistor is obtained by attaching silver palladium electrodes and platinum wire leads.

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