Heat-sensitive sensing material, wide-temperature-range Fe-doped manganese-based heat-sensitive sensor and preparation method thereof

Abstract

The invention discloses a heat-sensitive sensing material, a wide-temperature-range Fe-doped manganese-based heat-sensitive sensor and a preparation method of the wide-temperature-range Fe-doped manganese-based heat-sensitive sensor, the chemical formula of the heat-sensitive sensing material is Fe < x > Ni < 0.3 > Co < 0.9 > Mn < 1.8-x > O < 4 >, and The preparation method comprises the following steps: weighing raw materials MnCO3, NiO, Co3O4 and Fe3O4, carrying out ball milling, sintering, carrying out secondary ball milling to obtain heat-sensitive sensor active powder, uniformly mixing the obtained heat-sensitive sensor active powder with a polyvinyl alcohol aqueous solution, drying, grinding and sieving to obtain glue-mixed thermistor active powder; then tabletting the obtained thermistor active powder to obtain a heat-sensitive sensor rough blank; and carrying out secondary sintering on the obtained heat-sensitive sensor rough blank, and coating a silver electrode after the secondary sintering is finished, so as to obtain the wide-temperature-range Fe-doped manganese-based heat-sensitive sensor. The heat-sensitive sensing material and the wide-temperature-range Fe-doped manganese-based heat-sensitive sensor provided by the invention have the advantage of high precision when being used in a specific medium and low temperature range, and are good in temperature range adaptability.

Description

Technical Field

[0001] The invention relates to a manganese-based thermosensitive sensing material, and in particular to a thermosensitive sensing material and a wide-temperature-range Fe-doped manganese-based thermosensitive sensor and a preparation method thereof. Background Art

[0002] The temperature difference between day and night is large in plateau areas. Long-term service of equipment in this environment is prone to abnormal storage micro-environment temperature, resulting in performance degradation, abnormal protection system status and other problems. Temperature monitoring of equipment storage micro-environment is crucial to ensure stable and reliable equipment performance, especially for precision electronic instruments, which have high requirements for storage micro-environment status. For example, a certain type of product transport packaging box has requirements for micro-environment temperature. When the equipment storage micro-environment temperature is between -15℃ and +50℃, the micro-environment temperature needs to be accurately monitored in real time.

[0003] At present, traditional thermistors often cannot meet the needs of accurate temperature monitoring in a wide temperature range of -20℃~60℃. The temperature measurement range of most existing manganese-based thermistors is above room temperature. Therefore, the development of high-precision thermistors with a wide temperature range is particularly important. Traditional thermistors often have defects such as large accuracy fluctuations, poor linearity, or poor long-term stability in the wide temperature range of -20℃~60℃. For example, the sensitivity of a commonly used thermistor decreases significantly in the low temperature section, resulting in increased measurement errors; and some sensors are prone to performance drift when approaching the high temperature boundary, and cannot meet the requirements of long-term accurate monitoring. Therefore, it is very important to develop a thermistor specifically for this temperature range (-20℃~60℃) with high-precision characteristics. Summary of the invention

[0004] The present invention provides a thermosensitive sensing material and a wide-temperature range Fe-doped manganese-based thermosensitive sensor and a preparation method thereof, aiming to solve the problems of insufficient accuracy and poor temperature adaptability of existing thermosensitive sensors in a specific medium and low temperature range (-20°C ~ 60°C), and to provide reliable sensing technology support for many equipments that require accurate temperature monitoring in this temperature range.

[0005] The present invention adopts the following technical solution.

[0006] A thermosensitive sensing material, whose chemical formula is Fe x Ni 0.3 Co 0.9 Mn 1.8-x O4, x = 0.5 to 0.8. Preferably, the chemical formula of the thermosensitive sensing material is Fe 0.6 Ni 0.3 Co 0.9 Mn 1.2 O4.

[0007] A method for preparing a wide temperature range Fe-doped manganese-based thermal sensor, comprising: Step 1, weighing raw materials MnCO3, NiO, Co3O4, and Fe3O4, ball milling, vacuum filtering, and drying the raw materials to obtain powder materials; Step 2, sintering the obtained powder material, and performing secondary ball milling on the sintered material to obtain active powder for the thermal sensor; Step 3, mixing the obtained active powder of the thermistor with the polyvinyl alcohol aqueous solution, drying after mixing evenly, grinding and sieving to obtain the active powder of thermistor after mixing; and then tableting the obtained active powder of thermistor to obtain a rough blank of the thermistor; Step 4, the obtained rough thermal sensor blank is subjected to secondary sintering, and then coated with silver electrodes to obtain a wide temperature range Fe-doped manganese-based thermal sensor.

[0008] Preferably, the raw materials are weighed according to the amount of elemental substances, and the weighed raw materials meet the "Fe x Ni 0.3 Co 0.9 Mn 1.8-x04 (x=0.5~0.7)” This doping ratio requirement.

[0009] Preferably, the raw materials are weighed according to the amount of elemental substances, and the weighed raw materials meet the "Fe x Ni 0.3 Co 0.9 Mn 1.8-x04 (x=0.6)” This doping ratio requirement.

[0010] Preferably, in step 1, ultrapure water is used as a dispersant, and the ball-to-material ratio is controlled to be 2:1.

[0011] Preferably, the sintering method in step 2 is: firstly heating to 200°C at a rate of 5°C / min and keeping at that temperature for one hour, then heating to 900°C at a rate of 5°C / min, sintering for 3 hours and then cooling to room temperature.

[0012] Preferably, the tableting process in step 3 needs to be maintained under pressure for at least 90 seconds.

[0013] Preferably, the secondary sintering method in step 4 is: firstly heating to 600°C at a rate of 2°C / min and keeping at that temperature for 2 hours, then heating to 1150°C at a rate of 5°C / min, sintering for 3 hours and then cooling to room temperature.

[0014] In the present invention, during the sintering process in step 2, crystals of the active material of the thermosensitive sensor are formed.

[0015] Beneficial effects: The thermosensitive sensing material and wide-temperature range Fe-doped manganese-based thermosensitive sensor provided by the present invention have the advantages of high precision when used in a specific medium and low temperature range (-20℃~60℃), and have good temperature adaptability. The thermal constant B value, a key indicator of reaction sensitivity, is as high as 3839.59. It also has the advantages of low room temperature resistance and low energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The resistance-temperature test results of the wide temperature range Fe-doped manganese-based thermistor in Example 1; Figure 2 The room temperature resistance r25 test result of the wide temperature range Fe-doped manganese-based thermistor in Example 1; Figure 3 1 is the material constant B value test result of the wide temperature range Fe-doped manganese-based thermistor in Example 1. DETAILED DESCRIPTION

[0017] The technical solution of the present invention is described clearly and completely below 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 creative work are within the scope of protection of the present invention. Example 1

[0018] An Fe-doped manganese-based thermal sensor, whose chemical formula is Fe 0.6 Ni 0.3 Co 0.9 Mn 1.2 O4, a method for preparing a wide temperature range Fe-doped manganese-based thermal sensor, the steps comprising: Step 1, weighing raw materials MnCO3, NiO, Co3O4, and Fe3O4 (weighing according to the amount of elemental substances, the masses of MnCO3, NiO, Co3O4, and Fe3O4 are 9.55g, 1.55g, 5g, and 3.21g, respectively), drying the weighed raw materials in a vacuum drying oven, and then using a planetary ball mill for high-energy ball milling; using ultrapure water as a dispersant during the ball milling process, controlling the ball-to-material ratio of zirconium oxide balls to raw materials in the ball mill to be 2:1, using a sieve to filter out the ball mill beads after the ball milling is completed, and using a vacuum filtration to filter out the ground powder and dry it; Step 2, sintering the obtained powder material, and performing secondary ball milling on the sintered material to obtain active powder of thermistor sensor; specifically: firstly heating to 200°C at a rate of 5°C / min and keeping the temperature for one hour, then heating to 900°C at a rate of 5°C / min, sintering for 3 hours and cooling to room temperature, during which the crystals of active material of thermistor sensor are formed, and performing secondary ball milling after sintering (secondary ball milling method is the same as the ball milling method in step 1) to obtain fine active powder of thermistor sensor; Step 3, mixing the obtained active powder of the thermistor with a 6wt% polyvinyl alcohol aqueous solution, the mixing amount being 2ml of the polyvinyl alcohol aqueous solution for every 3g of the active powder, drying after mixing evenly, grinding and sieving to obtain the thermistor active powder after mixing; then tableting the obtained active powder of the thermistor (controlling the pressure of the tablet press to be 15Mpa, and the holding time to be two minutes) to obtain a rough blank of the thermistor; Step 4, the obtained thermistor rough blank is subjected to secondary sintering (first heated to 600°C at a rate of 2°C / min and kept at this temperature for 2 hours, then heated to 1150°C at a rate of 5°C / min, sintered for 3 hours and then cooled to room temperature), after which silver electrodes are coated and wires are led out to obtain a wide temperature range Fe-doped manganese-based thermistor. Example 2

[0019] An Fe-doped manganese-based thermal sensor, whose chemical formula is Fe 0.5 Ni 0.3 Co 0.9 Mn 1.3 O4. The preparation method of the wide temperature range Fe-doped manganese-based thermal sensor is the same as that in Example 1. Example 3

[0020] An Fe-doped manganese-based thermal sensor, whose chemical formula is Fe 0.7 Ni 0.3 Co 0.9 Mn 1.1 O4. The preparation method of the wide temperature range Fe-doped manganese-based thermal sensor is the same as that in Example 1. Example 4

[0021] An Fe-doped manganese-based thermal sensor, whose chemical formula is Fe 0.8 Ni 0.3 Co 0.9 Mn1O4, the preparation method of the wide temperature range Fe-doped manganese-based thermal sensor is the same as that in Example 1.

[0022] The performance of the Fe-doped manganese-based thermistors in each embodiment was tested, and a total of 4 groups of samples (two samples in each group) were selected, among which the sensor samples prepared in Example 1 were numbered A2-1 and A2-2, the sensor samples prepared in Example 2 were numbered A1-1 and A1-2, the sensor samples prepared in Example 3 were numbered A3-1 and A3-2, and the sensor samples prepared in Example 4 were numbered A4-1 and A4-2.

[0023] The four groups of samples were tested using a temperature and humidity environment box and a resistance tester. The test temperature range was -20℃ to 60℃. The resistance-temperature test results are shown in Figure 1 , room temperature resistance r25 test results see Figure 2 , material constant B value test results see Figure 3 .

[0024] After analyzing the performance test results of the four groups of samples, it was found that the comprehensive performance of group A2 samples (i.e., the Fe-doped manganese-based thermistor prepared in Example 1) was the most ideal. The test results of the two samples in group A2 had a high degree of fit and the thermal constant B value, a key indicator of reaction sensitivity, reached 3839.59. Its room temperature resistance was also low and it had low energy consumption.

[0025] The present invention uses four groups of active materials with specific Fe doping ratios and a specific preparation process to prepare thermosensitive sensing materials and wide-temperature range Fe-doped manganese-based thermosensitive sensors. They have the advantages of high precision when used in a specific medium and low temperature range (-20°C ~ 60°C) and good temperature adaptability. They also have the advantages of simple preparation process, good controllability, and low manufacturing cost.

Claims

1. A thermosensitive sensing material, characterized in that: Its chemical formula is Fe x Ni 0.3 Co 0.9 Mn 1.8-x O4, where x = 0.5 to 0.

8.

2. The thermosensitive sensing material according to claim 1, characterized in that: Its chemical formula is Feb 0.6 Ni 0.3 Co 0.9 Mr 1.2 O4.

3. A method for preparing a wide temperature range Fe-doped manganese-based thermal sensor, characterized in that the steps include: Step 1, weighing raw materials MnCO3, NiO, Co3O4, and Fe3O4, ball milling, vacuum filtering, and drying the raw materials to obtain powder materials; Step 2, sintering the obtained powder material, and performing secondary ball milling on the sintered material to obtain active powder for the thermal sensor; Step 3, mixing the obtained active powder of the thermistor with the polyvinyl alcohol aqueous solution, drying after mixing evenly, grinding and sieving to obtain the active powder of thermistor after mixing; and then tableting the obtained active powder of thermistor to obtain a rough blank of the thermistor; Step 4, the obtained rough thermal sensor blank is subjected to secondary sintering, and then coated with silver electrodes to obtain a wide temperature range Fe-doped manganese-based thermal sensor.

4. The preparation method according to claim 3, characterized in that: Weigh the raw materials according to the amount of elemental substances, and the weighed raw materials meet the "Fe x Ni 0.3 Co 0.9 Mn 1.8-x04 (x=0.5~0.7)” This doping ratio requirement.

5. The preparation method according to claim 3, characterized in that: Weigh the raw materials according to the amount of elemental substances, and the weighed raw materials meet the "Fe x Ni 0.3 Co 0.9 Mn 1.8-x04 (x=0.6)” This doping ratio requirement.

6. The preparation method according to claim 3, characterized in that: In step 1, ultrapure water is used as a dispersant, and the ball-to-material ratio of zirconium oxide balls to raw materials in the ball mill is controlled to be 2:

1.

7. The preparation method according to claim 3, characterized in that: The sintering method in step 2 is: firstly, the temperature is raised to 200°C at a rate of 5°C / min and then kept at that temperature for one hour, then the temperature is raised to 900°C at a rate of 5°C / min, and then cooled to room temperature after sintering for 3 hours.

8. The preparation method according to claim 3, characterized in that: When tableting in step 3, the pressure must be maintained for at least 90 seconds.

9. The preparation method according to claim 3, characterized in that: The secondary sintering method in step 4 is: firstly increase the temperature to 600°C at a rate of 2°C / min and keep it at that temperature for 2 hours, then increase the temperature to 1150°C at a rate of 5°C / min, sinter for 3 hours and then cool to room temperature.

10. The preparation method according to any one of claims 3 to 9, characterized in that: During the sintering process in step 2, crystals of the active material of the thermosensitive sensor are formed.

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