CN115536367A - High-resistance low-B-value thermistor ceramic body, preparation method and thermistor - Google Patents
High-resistance low-B-value thermistor ceramic body, preparation method and thermistor Download PDFInfo
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Abstract
The invention discloses a high-resistance low-B-value thermistor ceramic body, a preparation method and a thermistor, wherein the high-resistance low-B-value thermistor ceramic body comprises the following components in percentage by weight: 24-31% of Mn, 29-38%, 20-27% of Fe, 3-5% of Al, and doping with lithium oxide (Li) 2 O), lanthanum oxide (La) 2 O 3 ) And yttrium oxide (Y) 2 O 3 ) (ii) a The total doping amount is 4-27%. The high-resistance low-B-value thermistor ceramic body adopts a manganese-nickel-iron-aluminum quaternary system formula (Mn-Ni-Fe-Al), and alumina and lithium oxide (Li) are added on the basis of the ternary system (Mn-Ni-Fe) formula 2 O), lanthanum oxide (La) 2 O 3 ) And yttrium oxide (Y2O 3), has good stability by using lithium and rare earth elements, reduces eutectic point, and is sinteredThe temperature is low, so that the sintering temperature of the system is reduced by 125-75 ℃ (the sintering temperature is 1125-1175 ℃) compared with that of the common formula (1250 ℃), and the system can be well sintered and molded; and can save the electric energy in the high-temperature heat preservation area.
Description
Technical Field
The invention relates to the technical field of NTC thermistors, in particular to a high-resistance low-B-value thermistor ceramic body, a preparation method and a thermistor.
Background
NTC is an abbreviation of Negative Temperature Coefficient, which means Negative Temperature Coefficient, and generally refers to semiconductor material or component with large Negative Temperature Coefficient, so called thermistor is Negative Temperature Coefficient thermistor. It is made up by using metal oxides of manganese, cobalt and others as main material and adopting ceramic process. The thermistor can be widely applied to the occasions of temperature measurement, temperature compensation, surge current suppression and the like.
The development and production of electronic components must be directed toward miniaturization and intellectualization, which puts higher demands on high reliability and high stability of the electronic components.
To achieve high reliability and high stability of the thermistor, higher requirements are placed on the thermistor formulation. The prior NTC thermistor material with high B value and high stability and the production method thereof have higher sintering temperature. Therefore, it is of great significance to develop a low-temperature sintering high-stability NTC thermosensitive resistor body with high resistance and low B value (BF 100K 3435B) and a preparation method thereof.
Disclosure of Invention
The invention aims to provide a thermistor ceramic body with a high resistance value and a low B value, a preparation method and a thermistor, which have low sintering temperature and better reliability and stability.
The invention discloses a high-resistance low-B-value thermistor ceramic body which comprises the following components in percentage by weight: 24-31% of Mn, 29-38% of Ni, 20-27% of Fe, 3-5% of Al, and doping with lithium oxide (Li) 2 O), lanthanum oxide (La) 2 O 3 ) And yttrium oxide (Y) 2 O 3 ) (ii) a The total doping amount is 4-27%.
Optionally, the resistivity p of the resistor is between 9975 and 11025 Ω -cm (namely 10500 +/-5%), and the B value is between 3408 and 3462K.
The invention also discloses a preparation method of the high-resistance low-B-value thermistor ceramic body, which is used for preparing the high-resistance low-B-value thermistor ceramic body and is characterized by comprising the following steps of:
preparing materials: weighing raw material Mn according to a proportion 3 O 4 、NiO、Fe 2 O 3 、Al 2 O 3 、Li 2 O、La 2 O 3 And Y 2 O 3 ；
Primary ball milling: uniformly mixing the prepared raw materials, grinding and refining, and controlling the granularity (median diameter) D50 after grinding to be less than or equal to 0.4um;
primary drying: drying the ball-milled raw materials, controlling the drying temperature at 110-135 ℃, and cooling after drying;
powdering: pulverizing the dried raw materials and sieving;
pre-burning: presintering the powdered powder, wherein the presintering temperature is 950 ℃, and the heat preservation time in a high-temperature area is 2 hours;
secondary ball milling: performing secondary ball milling on the pre-sintered powder, and controlling the granularity (median diameter) D50 after grinding to be less than or equal to 0.35um;
secondary drying: drying the powder after the secondary ball milling, controlling the temperature of the dried powder at 100-110 ℃, cooling and sieving;
and (3) compression molding: pressing and molding the dried powder in an isostatic pressing molding machine;
and (3) high-temperature sintering: sintering at 1125 +/-5-1175 +/-5 ℃ for 7-10 h, and slicing to obtain the thermistor ceramic body with high resistance and low B value.
Optionally, in the step of batching, testing the moisture of each raw material by using a high-end digital halogen rapid moisture tester, wherein the testing temperature is 115 ℃, and the constant temperature discrimination time is 1min; and (5) proportioning according to the determined moisture.
Optionally, in the primary ball milling step, the raw materials are ground and refined by an omnibearing planetary ball mill in a wet method, the particle size is tested by a laser particle size analyzer, and the ground particle size is controlled.
Optionally, in the primary drying step, cooling is performed for 1.2 hours after drying.
Optionally, in the step of powdering, the dried raw material is powdered by a powdering machine, and sieved by a 60-mesh screen.
Optionally, in the pre-burning step, the powder is filled into the crucible to be eight to nine times full and is put into a nano-Bo furnace or a muffle furnace for pre-burning.
Optionally, in the secondary ball milling step, the refined powder is ground by an omnibearing planetary ball mill in a wet method, the particle size is tested by a laser particle sizer, and the ground particle size is controlled.
The invention also discloses a thermistor which comprises the high-resistance low-B-value thermistor ceramic body.
The high-resistance low-B-value (BF 100K 3435B) thermistor ceramic body adopts a manganese-nickel-iron-aluminum quaternary system formula (Mn-Ni-Fe-Al), and alumina and lithium oxide (Li) are added on the basis of the ternary system (Mn-Ni-Fe) formula 2 O), lanthanum oxide (La) 2 O 3 ) And yttrium oxide (Y) 2 O 3 ) The system sintering temperature is reduced by 125-75 ℃ (the sintering temperature is 1125-1175 ℃) compared with the common formula (1250 ℃) by utilizing the good stability of lithium and rare earth elements, the eutectic point is reduced, and the sintering temperature is low, so that the system can be well sintered and molded; and can save the electric energy in the high-temperature heat-preserving area, can conveniently adjust the resistivity and the B value of the material, make the size of the thermistor more reasonable, facilitate the production and improve the efficiency.
Detailed Description
It is to be understood that the terminology, the specific structural and functional details disclosed herein are for the purpose of describing particular embodiments only, and are not intended to be limiting, since the present invention may be embodied in many alternate forms and should not be construed as limited to only the embodiments set forth herein.
The invention is described in detail below with reference to alternative embodiments.
As an embodiment of the invention, a high-resistance low-B value (BF 100K 3435B) thermistor ceramic body is disclosed, which comprises the following components in percentage by weight: 24-31% of Mn, 29-38% of Ni, 20-27% of Fe, 3-5% of Al, and doping with lithium oxide (Li) 2 O), lanthanum oxide (La) 2 O 3 ) And yttrium oxide (Y) 2 O 3 ) (ii) a The total doping amount is 4-27%.
The high-resistance low-B-value (BF 100K 3435B) thermistor ceramic body adopts a manganese-nickel-iron-aluminum quaternary system formula (Mn-Ni-Fe-Al), and alumina and lithium oxide (Li) are added on the basis of the ternary system (Mn-Ni-Fe) formula 2 O), lanthanum oxide (La) 2 O 3 ) And yttrium oxide (Y) 2 O 3 ) The system sintering temperature is reduced by 125-75 ℃ (the sintering temperature is 1125-1175 ℃) compared with the common formula (1250 ℃) by utilizing the good stability of lithium and rare earth elements, the eutectic point is reduced, and the sintering temperature is low, so that the system can be well sintered and molded; the electric energy in a high-temperature heat preservation area can be saved, the resistivity and the B value of the material can be conveniently adjusted, the size of the thermistor is more reasonable, the production is convenient, and the efficiency is improved. Most importantly, the high precision, the qualification rate and the high temperature stability of the product can be effectively improved. Compared with a manganese-cobalt-iron (Mn-Co-Fe) ternary system, the formula system has the advantages that expensive cobalt is replaced by nickel, the cost of raw materials is reduced greatly, and the product performance is better.
Specifically, the grain of the thermistor ceramic body with high resistance and low B value (BF 100K 3435B) is in an octahedral spinel structure in a microscopic mode. The crystal composition formula is AB 2 O 4 Wherein A is a divalent metal ion, such as: mn (Mn) 2+ ，Fe 2+ ，Co 2+ ,Ni 2+ . Wherein B is a trivalent metal ion, such as Al 3+ ，Fe 3+ ，Co 3+ ，Mn 3+ .. The quaternary system Mn-Ni-Fe-Al of the invention forms NiMn 2 O 4 Main crystal phase and MnAl 2 O 4 ,FeAl 2 O 4 The conduction mechanism is as follows:
Mn 2+ +Mn 3+ →Mn 3+ +Mn 2+
the quaternary system of the invention is insensitive to impurities compared with the ternary system, mn, ni, fe and Al form a main crystal phase, mn reduces the sensitivity to impurities, al is doped to conveniently adjust resistivity, li 2 The volume resistivity is influenced by the O doping amount, the volume resistivity can be regulated and controlled by reasonably controlling the dosage, namely, the resistance value is controlled, and lanthanum oxide La is added into the formula 2 O 3 And yttrium oxide Y 2 O 3 The sintering property of the ceramic can be improved, the porosity is reduced, the compactness is improved, the microstructure and the phase composition are improved, and the application performance of the NTC ceramic can be improved. Rare earth oxide lanthanum oxide La 2 O 3 And yttrium oxide Y 2 O 3 As a fusing agent, the ceramic powder can promote sintering, improve the microstructure of the ceramic and play a role in doping modification.
Specifically, the resistivity rho of the resistor is between 9975 and 11025 omega cm (namely 10500 +/-5 percent), and the B value is between 3408 and 3462K.
The invention also discloses a preparation method of the high-resistance low-B value (BF 100K 3435B) thermistor ceramic body, which is used for preparing the high-resistance low-B value (BF 100K 3435B) thermistor ceramic body, and specifically comprises the following steps:
preparing materials: weighing raw material Mn in proportion 3 O 4 、NiO、Fe 2 O 3 、Al 2 O 3 、Li 2 O、La 2 O 3 And Y 2 O 3 ；
Primary ball milling: uniformly mixing the prepared raw materials, grinding and refining, and controlling the granularity (median diameter) D50 after grinding to be less than or equal to 0.4um;
primary drying: drying the ball-milled raw materials, controlling the drying temperature at 110-135 ℃, and cooling after drying;
powdering: pulverizing the dried raw materials and sieving;
pre-burning: presintering the powdered powder, wherein the presintering temperature is 950 ℃, and the heat preservation time in a high-temperature area is 2 hours;
secondary ball milling: performing secondary ball milling on the pre-sintered powder, and controlling the particle size (median diameter) D50 after grinding to be less than or equal to 0.35um;
secondary drying: drying the powder after the secondary ball milling, controlling the temperature of the dried powder at 100-110 ℃, cooling and sieving;
and (3) compression molding: pressing and molding the dried powder in an isostatic pressing molding machine;
and (3) high-temperature sintering: sintering at 1125 +/-5-1175 +/-5 ℃ for 7-10 h, and slicing to obtain the high-resistance low-B-value (BF 100K 3435B) thermistor ceramic body.
According to the preparation method of the high-resistance low-B-value (BF 100K 3435B) thermistor ceramic body, the sintering temperature is only 1125 +/-5-1175 +/-5 ℃, the sintering temperature is low, and meanwhile, the thermistor ceramic body can be well sintered and molded through a manganese-nickel-iron-aluminum quaternary system formula; and the electric energy in a high-temperature heat preservation area can be saved, the resistivity and the B value of the material can be conveniently adjusted, and the high precision, the qualification rate and the high-temperature stability of the product can be effectively improved. Compared with a manganese-cobalt-iron (Mn-Co-Fe) ternary system, the formula system has the advantages that expensive cobalt is replaced by nickel, the cost of raw materials is reduced greatly, and the product performance is better.
Specifically, in the step of batching, a high-end digital halogen rapid moisture tester is used for testing the moisture of each raw material, the testing temperature is 115 ℃, and the constant temperature discrimination time is 1min; according to the moisture measurement, the high-end digital halogen rapid moisture meter is used for measuring the moisture of the raw materials, so that the proportioning is more accurate.
Specifically, in the primary ball milling step, the raw materials are ground and refined by an omnibearing planetary ball mill in a wet method, the particle size is tested by a laser particle sizer, and the ground particle size is controlled. The particle size is tested by a laser particle sizer, and the particle size distribution of the powder is effectively controlled. In the primary drying step, cooling is carried out for 1.2h after drying, and drying is carried out fully. The wet grinding refinement of the omnibearing planetary ball mill can reach hundreds of nanometers, and the components are more uniform. In the step of press forming, the isostatic pressing technology can improve the consistency of the blank.
Specifically, in the step of powdering, the dried raw materials are powdered by a powdering machine, and sieved by a 60-mesh screen. In the pre-burning step, powder is filled into a crucible to eight to nine full and is put into a Nabo furnace or a muffle furnace for pre-burning. In the secondary ball milling step, the refined powder is ground by an omnibearing planetary ball mill in a wet method, the granularity is tested by a laser particle sizer, and the granularity after grinding is controlled.
It is emphasized that the technical solution of the present invention has the following innovation points:
(1) the high-end digital halogen rapid moisture tester is adopted to test the moisture of the raw materials, so that the proportioning is more accurate,
(2) the wet grinding refinement of the omnibearing planetary ball mill reaches hundreds of nanometers, and the components are more uniform.
(3) The particle size is tested by a laser particle sizer, and the particle size distribution of the powder is effectively controlled.
(4) And the consistency of the blank is improved by adopting an advanced isostatic pressing technology.
(5) Adopting rare earth element lanthanum sesquioxide (La) 2 O 3 ) And yttrium oxide (Y) 2 O 3 ) (ii) a And lithium oxide (Li) 2 O)，Li 2 The volume resistivity is influenced by the O doping amount, the volume resistivity can be regulated and controlled by reasonably controlling the dosage, namely, the resistance value is controlled, and lanthanum oxide La is added into the formula 2 O 3 And yttrium oxide Y 2 O 3 The sintering property of the ceramic can be improved, the porosity is reduced, the compactness is improved, the microstructure and the phase composition are improved, and the application performance of the NTC ceramic can be improved. Rare earth oxide lanthanum oxide La 2 O 3 And yttrium oxide Y 2 O 3 As a fusing agent, the ceramic powder can promote sintering, improve the microstructure of the ceramic and play a role in doping modification.
The invention also discloses a thermistor which comprises the high-resistance low-B value (BF 100K 3435B) thermistor ceramic body.
The following is a detailed description of specific embodiments.
Example 1
The thermistor of the embodiment comprises the following raw materials in parts by weight: manganese (26%); nickel (32%); iron (23%); al (3%), lithium oxide and lanthanum oxide (La) as trace rare-earth element 2 O 3 ) And yttrium oxide (Y) 2 O 3 ) (ii) a The total doping is 16%.
(1) Preparing materials: the main raw material has Mn 3 O 4 、NiO、Fe 2 O 3 、Al 2 O 3 、Li 2 O、La 2 O 3 And Y 2 O 3 (ii) a Before use, a high-end digital halogen rapid moisture tester is used for testing the moisture of the raw materials, the testing temperature is 115 ℃, and the constant temperature discrimination time is 1min;
(2) Primary ball milling: uniformly mixing the prepared raw materials, carrying out wet grinding and refining by using an omnibearing planetary ball mill, testing the granularity by using a laser particle sizer, and controlling the granularity (median diameter) D50 after grinding to be less than or equal to 0.4um;
(3) Drying: filling the ground slurry into a special stainless steel baking pan, controlling the temperature of the baked slurry to be 110-135 ℃, cooling the powder discharged from the baking oven for 1.2hr, and then pouring the cooled powder into a charging barrel;
(4) Powdering: pulverizing the dried powder blocks which are not pre-sintered by using a special pulverizing machine, sieving by using a 60-mesh sieve, and filling by using a special or clean charging bucket;
(5) Pre-burning: loading the pulverized powder in a special crucible with eight to nine times, presintering in a Nabo furnace or a muffle furnace at 950 deg.C for 2hr;
(6) Secondary ball milling: performing secondary ball milling on the pre-sintered powder, performing wet grinding and refining by using an omnibearing planetary ball mill, testing the granularity by using a laser particle sizer, and controlling the granularity (median diameter) D50 after grinding to be less than or equal to 0.35um;
(7) And (3) drying: using a special stainless steel baking pan to contain the slurry subjected to secondary ball milling, controlling the baking temperature at 100-110 ℃, cooling the powder discharged from the baking oven for 1.2hr, and then pouring the powder into a charging barrel;
(8) And (3) pressing and forming: pressing and molding the dried powder in an isostatic pressing machine by using the pressure of 250 MPa;
(9) And (3) high-temperature sintering: sintering at 1125 + -5 deg.C to 1175 deg.C + -5 deg.C for 7-10 hr;
(10) And slicing, electrode mounting and scribing to obtain a finished product.
And finally, slicing the rough finished product, printing silver and burning silver, and installing an upper electrode glass seal to obtain the thermistor.
The resistivity rho of the prepared resistor body is 9997 omega cm; b value (B) 25/85 ) 3423; the consistency of the centering piece (the center position and the edge) is less than 1 percent; the consistency of the edge-locating pieces (the center position and the edge) is less than 1 percent; the consistency between the central position of the middle plate and the central position of the side plate is less than 1 percent. Aging at 300 deg.C for 24hr to obtain resistance drift rate less than 3 ‰; aging at 300 deg.C for 48hr has a resistance drift rate (less than that after aging at 300 deg.C for 24 hr) < 2 ‰. The resistance performance is excellent.
Example 2
The thermistor of the embodiment comprises the following raw materials in parts by weight: manganese (28%); nickel (30%); iron (21%); al (4%); doped with alumina, lithium oxide and trace rare earth element lanthanum oxide (La) 2 O 3 ) And yttrium oxide (Y) 2 O 3 ) (ii) a The total doping was 17%.
The preparation process comprises the following steps:
(1) Preparing materials: the main raw material is Mn 3 O 4 、NiO、Fe 2 O 3 、Al 2 O 3 、Li 2 O、La 2 O 3 And Y 2 O 3 (ii) a Before use, a high-end digital halogen rapid moisture tester is used for testing the moisture of the raw materials, the testing temperature is 115 ℃, and the constant temperature discrimination time is 1min;
(2) Primary ball milling: uniformly mixing the prepared raw materials, carrying out wet grinding and refining by using an omnibearing planetary ball mill, testing the granularity by using a laser particle sizer, and controlling the granularity (median diameter) D50 after grinding to be less than or equal to 0.4um;
(3) Drying: filling the ground slurry into a special stainless steel baking pan, controlling the temperature of the baked slurry to be 110-135 ℃, cooling the powder taken out of the baking oven for 1.2hr, and then pouring the cooled powder into a charging barrel;
(4) Powdering: pulverizing the dried powder blocks which are not pre-sintered by using a special powder pulverizing machine, sieving by using a 60-mesh sieve, and filling by using a special or clean charging barrel;
(5) Pre-burning: placing the pulverized powder in a special crucible, placing in a Nabo furnace or a muffle furnace, presintering at 950 deg.C for 2hr;
(6) Secondary ball milling: performing secondary ball milling on the pre-sintered powder, performing wet grinding and refining by using an omnibearing planetary ball mill, testing the granularity by using a laser particle sizer, and controlling the granularity (median diameter) D50 after grinding to be less than or equal to 0.35um;
(7) And (3) drying: using a special stainless steel baking pan to contain the slurry subjected to secondary ball milling, controlling the baking temperature at 100-110 ℃, cooling the powder discharged from the baking oven for 1.2hr, and then pouring the powder into a charging barrel;
(8) And (3) compression molding: pressing and molding the dried powder in an isostatic pressing machine by using the pressure of 250 MPa;
(9) And (3) high-temperature sintering: sintering at 1125 + -5 deg.C to 1175 deg.C + -5 deg.C for 7-10 hr;
(10) And slicing, electrode mounting and scribing to obtain a finished product.
And finally, slicing the rough finished product, printing silver and burning silver, and installing an upper electrode glass seal to obtain the thermistor.
The resistivity rho of the prepared resistor body is 10584 omega cm; b value(B 25/85 ) 3437; the consistency of the centering piece (the center position and the edge) is less than 1 percent; the consistency of the edge-locating pieces (the center position and the edge) is less than 1 percent; the consistency of the center position of the centering sheet and the center position of the centering sheet is less than 1 percent. Aging at 300 deg.C for 24hr to obtain resistance drift rate less than 2 ‰; aging at 300 deg.C for 48hr has a resistance drift rate (less than that after aging at 300 deg.C for 24 hr) < 3 ‰. The resistance performance is excellent.
Example 3
The thermistor (BF 100K 3435B) of the present embodiment comprises the following raw material components in parts by weight: manganese (25%); nickel (34%); iron (25%); aluminum (5%); doped lithium oxide and trace rare earth element lanthanum oxide (La) 2 O 3 ) And yttrium oxide (Y) 2 O 3 ) (ii) a The total doping amount is 11%.
The preparation process comprises the following steps:
(1) Preparing materials: the main raw material has Mn 3 O 4 、NiO、Fe 2 O 3 、Al 2 O 3 、Li 2 O、La 2 O 3 And Y 2 O 3 (ii) a Before use, a high-end digital halogen rapid moisture tester is used for testing the moisture of the raw materials, the testing temperature is 115 ℃, and the constant temperature discrimination time is 1min;
(2) Primary ball milling: uniformly mixing the prepared raw materials, carrying out wet grinding and refining by using an omnibearing planetary ball mill, testing the granularity by using a laser particle sizer, and controlling the granularity (median diameter) D50 after grinding to be less than or equal to 0.4um;
(3) Drying: filling the ground slurry into a special stainless steel baking pan, controlling the temperature of the baked slurry to be 110-135 ℃, cooling the powder discharged from the baking oven for 1.2hr, and then pouring the cooled powder into a charging barrel;
(4) Powdering: pulverizing the dried powder blocks which are not pre-sintered by using a special pulverizing machine, sieving by using a 60-mesh sieve, and filling by using a special or clean charging bucket;
(5) Pre-burning: loading the pulverized powder in a special crucible with eight to nine times, presintering in a Nabo furnace or a muffle furnace at 950 deg.C for 2hr;
(6) Secondary ball milling: performing secondary ball milling on the pre-sintered powder, performing wet grinding and refining by using an omnibearing planetary ball mill, testing the granularity by using a laser particle sizer, and controlling the granularity (median diameter) D50 after grinding to be less than or equal to 0.35um;
(7) Drying: using a special stainless steel baking pan to contain the slurry subjected to secondary ball milling, controlling the temperature of the baked slurry to be 100-110 ℃, cooling the powder discharged from the baking oven for 1.2 hours, and then pouring the cooled powder into a charging barrel;
(8) And (3) pressing and forming: in an isostatic pressing forming machine, the dried powder is pressed and formed by using 250MPa pressure;
(9) And (3) high-temperature sintering: sintering at 1125 + -5 deg.C to 1175 deg.C + -5 deg.C for 7-10 hr;
(10) And slicing, electrode mounting and scribing to obtain a finished product.
And finally, slicing the rough finished product, printing silver and burning silver, and installing an upper electrode glass seal to obtain the thermistor.
The resistivity rho of the prepared resistor body is 10657 omega cm; b value (B) 25/85 ) 3445; the consistency of the centering piece (the center position and the edge) is less than 1 percent; the consistency of the edge-locating pieces (the center position and the edge) is less than 1 percent; the consistency of the center position of the centering sheet and the center position of the centering sheet is less than 1 percent. Aging at 300 deg.C for 24hr to obtain resistance drift rate less than 2 ‰; aging at 300 deg.C for 48hr to obtain a resistance drift rate of less than 3 ‰. The resistance performance is excellent.
Comparative example 1
The thermistor of the comparative example comprises the following raw materials in percentage by weight: mn (24.1%), co (59.1%), fe (16.8%). The preparation process is the same as in example 1.
Comparative example 2
The thermistor of the comparative example comprises the following raw materials in percentage by weight: mn (40.0%), ni (39.1%), fe (20.9%). The preparation process is the same as in example 1.
The results of the performance parameter testing and reliability testing of the examples are as follows:
performance parameters of Mn-Ni-Fe-Al series products
Reliability test results of Mn-Ni-Fe-Al series products
Comparative example 1 (Mn-Co-Fe) thermistor Performance parameters
Comparative example 1 (Mn-Co-Fe) thermistor reliability test results
Comparative example 2 (Mn-Ni-Fe) thermistor Performance parameters
Comparative example 2 (Mn-Ni-Fe) reliability test results of thermistor
From the above data, it can be seen that the thermistors of the present invention performed better than the thermistors of comparative examples 1 and 2.
It should be noted that, the limitations of the steps involved in the present disclosure are not considered to limit the order of the steps without affecting the implementation of the specific embodiments, and the steps written in the foregoing may be executed first, or executed later, or even executed simultaneously, and as long as the present disclosure can be implemented, all should be considered to belong to the protection scope of the present disclosure.
The foregoing is a further detailed description of the invention in connection with specific alternative embodiments and is not intended to limit the invention to the specific embodiments described herein. For those skilled in the art to which the invention pertains, several simple deductions or substitutions can be made without departing from the spirit of the invention, and all shall be considered as belonging to the protection scope of the invention.
Claims (10)
1. A thermistor ceramic body with high resistance and low B value is characterized by comprising the following components in percentage by weight: 24-31% of Mn, 29-38%, 20-27% of Fe, 3-5% of Al, and doping with lithium oxide (Li) 2 O), lanthanum oxide (La) 2 O 3 ) And yttrium oxide (Y) 2 O 3 ) (ii) a The total doping amount is 4-27%.
2. The ceramic high-resistivity low-B thermistor body according to claim 1, wherein the resistivity p of the resistor body is 9975 to 11025 Ω -cm (i.e., 10500. + -. 5%) and the B value is 3408 to 3462K.
3. A method for producing a high-resistance low-B thermistor ceramic body, which is used for producing the high-resistance low-B thermistor ceramic body according to claim 1 or 2, comprising the steps of:
preparing materials: weighing raw material Mn in proportion 3 O 4 、NiO、Fe 2 O 3 、Al 2 O 3 、Li 2 O、La 2 O 3 And Y 2 O 3 ；
Primary ball milling: uniformly mixing the prepared raw materials, grinding and refining, and controlling the granularity (median diameter) D50 after grinding to be less than or equal to 0.4um;
primary drying: drying the ball-milled raw materials, controlling the drying temperature at 110-135 ℃, drying and cooling;
powdering: pulverizing the dried raw materials and sieving;
pre-burning: presintering the powdered powder, wherein the presintering temperature is 950 ℃, and the heat preservation time in a high-temperature area is 2 hours;
secondary ball milling: performing secondary ball milling on the pre-sintered powder, and controlling the granularity (median diameter) D50 after grinding to be less than or equal to 0.35um;
secondary drying: drying the powder after the secondary ball milling, controlling the drying temperature at 100-110 ℃, cooling and sieving;
and (3) compression molding: pressing and molding the dried powder in an isostatic pressing molding machine;
and (3) high-temperature sintering: sintering at 1125 +/-5-1175 +/-5 ℃ for 7-10 h, and slicing to obtain the thermistor ceramic body with high resistance and low B value.
4. The preparation method according to claim 3, wherein in the step of compounding, the moisture of each raw material is tested by a high-end digital halogen rapid moisture tester, the test temperature is 115 ℃, and the constant temperature judgment time is 1min; and (5) proportioning according to the determined moisture.
5. The method according to claim 3, wherein in the primary ball milling step, the raw material is ground and refined by an all-directional planetary ball mill, the particle size is measured by a laser particle sizer, and the particle size after grinding is controlled.
6. The method of claim 3, wherein in the primary drying step, the primary drying is followed by cooling for 1.2 hours.
7. The method according to claim 3, wherein in the powdering step, the dried raw material is powderized by a powdering machine and sieved with a 60-mesh sieve.
8. The method of claim 3, wherein in the pre-firing step, the powder is charged into the crucible to eight to nine full and is pre-fired in a Nabo furnace or a muffle furnace.
9. The method according to claim 3, wherein in the secondary ball milling step, the refined powder is wet-milled using an all-directional planetary ball mill, the particle size is measured using a laser particle sizer, and the milled particle size is controlled.
10. A thermistor characterized by comprising the high-resistance low-B thermistor ceramic body according to claim 1 or 2.
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