CN100415414C - High precision thermosensitive resistor nanometer powder production method - Google Patents
High precision thermosensitive resistor nanometer powder production method Download PDFInfo
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- CN100415414C CN100415414C CNB2005100606563A CN200510060656A CN100415414C CN 100415414 C CN100415414 C CN 100415414C CN B2005100606563 A CNB2005100606563 A CN B2005100606563A CN 200510060656 A CN200510060656 A CN 200510060656A CN 100415414 C CN100415414 C CN 100415414C
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Abstract
The present invention discloses a production method of nanometer powder for preparing a high-precision thermal resistor. The production method comprises the steps that nitrate of Cr, Ni, and Mn are used as raw materials, citrate, carbowax and ammonia are added, heated and stirred, transparent colloidal liquid is formed by a hydrolyzing reaction and an aggregating reaction, and dried to obtain the dry gel which self-ignites to obtain powdery nanometer powder products. The present invention has the advantages that citrate combustion method is used for preparing powder after the gel is obtained, the present invention has low price of raw materials, simple and convenient operation, good physical and chemical properties of the burnt powder, the grain size of the powder can reach 40 to 60 nanometers, the powder is spinel structure phase, the sintered grain size is 1 to 2 mu m, the powder preparation has good repeatability, the rate of finished products reaches more than 80%, the powder which is used as raw materials can produce thermal the resistor with high precision B value and high consistency of resistance in the sintering block range, and the produced thermal resistor has good heat resistance and aging resistance.
Description
Technical field
The present invention relates to a kind of high-precision thermistor, especially relate to a kind of nano-powder that is used to prepare high precision thermosensitive resistor.
Background technology
At present; negative tempperature coefficient thermistor has been applied to temperature control, TEMP more and more, has prevented in the circuit such as overcurrent protector of surge current and crystal oscillator compensation; accounted for more than 40% of being produced of temperature sensor in recent years; the characteristics of negative tempperature coefficient thermistor are to be exponential relationship and to reduce with temperature its resistance value that raises, and its great majority are to be made by the oxide of transient metal Mn, Ni, Co, Fe, Cu, Cr etc.
Preparing the general traditional handicraft of thermo-responsive resistive oxide powder is mechanical milling method, factors such as the uniformity of the powder chemical constituent of this method preparation is not high, powder granule degree big (micron order) and poor repeatability have all produced harmful effect to postchannel process and chip, cause the yield rate of product low, precision is low.People begin to utilize sol-gel process to prepare the precision height, the negative tempperature coefficient thermistor of high conformity now.With respect to traditional preparation negative tempperature coefficient thermistor, sol-gel method has: 1. raw material has high-purity, not the impurity introduced of process such as grinding; 2. be reflected in the solution and carry out, uniformity height can reach molecule or atom level to the multi-component uniformity; 3. sintering temperature has bigger reduction, and major part is reflected under 2000 ℃ all can carry out.4. belong to the molecule level and mix non-general physical blending, so be difficult for having the phenomenon that is separated to produce; 5. sol-gel technology and equipment are simple, cost is low, and is easy to utilize, is applicable to batch process.Sol-gel process is expected to obtain comparatively ideal thermistor yield rate and electric property thereof owing to obtain the powder of nanometer size under the uniform situation of chemistry.As on November 29th, 2003 disclosed application number be the manufacture method that discloses a kind of metal-oxide semiconductor (MOS) thermistor in No. 03129082.5 Chinese invention patent ublic specification of application, with magnesium, aluminium, manganese, the acetate of nickel or nitrate are as raw material, adopt sol-gel process to prepare nano metal colloidal sol earlier, then with the colloidal sol drying and dehydrating, pulverize, decompose, burn till nano level metal-oxide powder in advance, carry out moulding again, Deng static pressure and high temperature sintering, cut into slices thereafter, the blackening electrode, be diced into thermistor chip, encapsulation at last makes high conformity, long-time stability are good, use the thermistor of wide temperature region.
Summary of the invention
Technical problem to be solved by this invention is to provide a kind of nano-powder that is used to prepare high precision thermosensitive resistor at above-mentioned prior art present situation, and the granularity of powder is little, resistance uniformity height in the sintering block scope; With the negative tempperature coefficient thermistor precision height of this powder preparation, good stability, and has good ageing resistace.
The present invention solves the problems of the technologies described above the technical scheme that is adopted: a kind of nano-powder that is used to prepare high precision thermosensitive resistor, it with the nitrate of Cr, Ni, Mn as raw material, add citric acid, polyethylene glycol and ammoniacal liquor, after adding thermal agitation, form vitreosol liquid through hydrolysis and polymerisation, will obtain after the sol liquid drying dry gel, the gel of drying carried out spontaneous combustion after, promptly obtain Powdered nano-powder product.
Specifically follow these steps to make:
A, take by weighing Cr, Ni, Mn respectively nitrate as raw material, its molar ratio is: Cr: Ni: Mn=5-15: 30: 55-65, mix and to dissolve in the deionized water, control metal ion molar concentration is: 0.1-0.4mol/L is configured to major constituent solution;
B, add citric acid and polyethylene glycol is made mixed liquor in the major constituent solution for preparing, regulate pH=3～5 of mixed liquor then with ammoniacal liquor, the molal quantity summation of metal ion is 1: 1.6～2.4 with the ratio of citric acid in mixed liquor;
C, with mixed liquor through adding thermal agitation 0.5～1 hour, through hydrolysis and polymerisation, form the vitreosol of pitchy, sol liquid is positioned in 120 ℃ the drying box, obtains dry gel after the dehydration;
The gel of d, the drying that will obtain is put into Muffle furnace, carries out spontaneous combustion after 2 hours in insulation under 450 ℃～500 ℃ the temperature and handles, and removing organic principle wherein, and obtains black loose powder shape nano-powder product.
Compared with prior art, the invention has the advantages that method 1. of the present invention adopts combustion method of citric acid to prepare powder after making colloid, the raw materials used citric acid low price of this method, simple to operation, powder physico-chemical property after the burning is good, the powder granule degree that obtains reaches 40-60 nanometer (see figure 1), and powder is a spinel structure phase (see figure 2), and granularity is in 1-2 μ m (see figure 2) behind the sintering; 2. because method of the present invention at first forms even, transparent mixing material from the metal inorganic salt of solubility the aqueous solution, under the effect of complex compound, generate colloid then, carry out spontaneous combustion again, therefore guaranteed the chemical uniformity of oxide system all the time; 3. the nitrate of selecting Mn, Ni, Cr for use is as raw material, the negative tempperature coefficient thermistor precision height of preparation, good stability, because Cr has resistant to thermal aging performance preferably, therefore select for use the nitrate of the Cr of proper ratio the resistant to thermal aging performance that improves thermistor to be had good effect as raw material, from the experiment test curve of Fig. 3, we can find that the adding of Cr can reduce the relative resistance rate of change effectively, and the resistant to thermal aging performance of thermistor nearly can improve 46%; 4. the good reproducibility of powder preparation, yield rate reaches more than 80%, with this powder is raw material, behind briquetting and sintering, prepare the thermistor of resistance uniformity height (under uniform temp, the resistance test difference of zones of different is minimum) in degree of precision B value (all greater than 4000K) (see figure 4), the sintering block scope.
Description of drawings
Fig. 1 is the ESEM collection of illustrative plates of CrxNi1.0Mn2.0-xO4 of the present invention (x=0.1,0.2,0.3,0.4) powder after 440 ℃ of spontaneous combustions;
Fig. 2 is the ESEM collection of illustrative plates of CrxNi1.0Mn2.0-xO4 of the present invention (x=0.1,0.2,0.3,0.4) sample behind 1100 ℃ of sintering;
Fig. 3 is the X-ray powder diffraction figure of CrxNi1.0Mn2.0-xO4 of the present invention powder after 440 ℃ of spontaneous combustions;
Fig. 4 is the X-ray powder diffraction figure of CrxNi1.0Mn2.0-xO4 of the present invention sample behind 1100 ℃ of sintering;
Fig. 5 is the influence of the stability (Δ R25/R25) of thermistor to CrNiMnO4 for Cr content of the present invention;
Fig. 6 is for using the prepared thermistor resistance of method of the present invention and traditional high temperature sintering method and the table of comparisons of accuracy value respectively, A1 in the table, A2, A3 is respectively resistance value and an accuracy value measured in the example one, two, three, B1, B2, B3 are under same ratio, utilize the resistance value and the accuracy value of traditional resulting negative tempperature coefficient thermistor of high temperature sintering method.
The specific embodiment
Below in conjunction with embodiment the present invention is described in further detail.
Embodiment one: example is at first in molar ratio: Cr: Ni: Mn=5: 30: 65, the nitrate that takes by weighing 0.0005 mole, 0.003 mole, 0.0065 mole Cr, Ni, Mn respectively is as raw material, mix and dissolve in the 67mL deionized water, control metal ion molar concentration is: 0.15mol/L is configured to major constituent solution; The citric acid and the 9g polyethylene glycol (PEG) that add 3.89g in the solution for preparing are made mixed liquor, and with the pH=3 of ammoniacal liquor adjusting mixed liquor, the molal quantity summation of metal ion is 1: 1.6 with the ratio of citric acid in mixed liquor; Mixed liquor through adding thermal agitation 0.5 hour, along with the carrying out of hydrolysis and polymerisation, is formed the vitreosol of brown, sol liquid is positioned in 120 ℃ the drying box, obtain dry brown gel; The dry brown gel that obtains is put into Muffle furnace, carry out spontaneous combustion after 2 hours in insulation under 450 ℃ the temperature and handle, removing organic principle wherein, and obtain the nano-powder product of black loose powder shape.Prepared powder is made the sample of thick 1mm diameter 10mm under the pressure of 50Mpa, sintering formed fine and close polycrystalline ceramics thin slice in 2 hours in 1100 ℃ silicon carbide rod furnace then, with two the surface soldered lead-in wires of silver slurry to sample, adopt resin-encapsulate, obtain the NTC thermistor at last.After tested, 85 ℃ of resistance are 301 Ω cm, and 25 ℃ of resistance are 3110 Ω cm, and B25/85 constant (K) is 4156, and the relative resistance rate of change of placing 25 ℃ of resistance after 400 hours in 125 ℃ of environment is lower than 0.35%.
Embodiment two: example is at first in molar ratio: Cr: Ni: Mn=10: 30: 60, the nitrate that takes by weighing 0.001 mole, 0.003 mole, 0.006 mole Cr, Ni, Mn respectively is as raw material, mix and dissolve in the 40mL deionized water, control metal ion molar concentration is: 0.25mol/L is configured to major constituent solution; The citric acid and the 10g polyethylene glycol (PEG) that add people 4.86g in the solution for preparing are made mixed liquor, and with the pH=4 of ammoniacal liquor adjusting mixed liquor, the molal quantity summation of metal ion is 1: 2.0 with the ratio of citric acid in mixed liquor; Mixed liquor through adding thermal agitation 0.7 hour, along with the carrying out of hydrolysis and polymerisation, is formed the colloidal sol of brown, sol liquid is positioned in 120 ℃ the drying box, obtain dry pitchy gel; The dry pitchy gel that obtains is put into Muffle furnace, carry out spontaneous combustion after 2.5 hours in insulation under 470 ℃ the temperature and handle, removing organic principle wherein, and obtain the nano-powder product of black loose powder shape.Prepared powder is made the sample of thick 1mm diameter 10mm under the pressure of 60Mpa, sintering formed fine and close polycrystalline ceramics thin slice in 3 hours in 1100 ℃ silicon carbide rod furnace then, with two the surface soldered lead-in wires of silver slurry to sample, adopt resin-encapsulate, obtain the NTC thermistor at last.After tested, 85 ℃ of resistance are 426 Ω cm, and 25 ℃ of resistance are 4250 Ω cm, and B25/85 constant (K) is 4203, and the relative resistance rate of change of placing 25 ℃ of resistance after 400 hours in 125 ℃ of environment is lower than 0.33%.
Embodiment three: example is at first in molar ratio: Cr: Ni: Mn=15: 30: 55, the nitrate that takes by weighing 0.0015 mole, 0.003 mole, 0.0055 mole Cr, Ni, Mn respectively is as raw material. and mix and dissolve in the 25mL deionized water, control metal ion molar concentration is: 0.4mol/L is configured to major constituent solution; The citric acid and the 12g polyethylene glycol (PEG) that add 583g in the solution for preparing are made mixed liquor, and with the pH=5 of ammoniacal liquor adjusting mixed liquor, the molal quantity summation of metal ion is 1: 2.4 with the ratio of citric acid in mixed liquor; Mixed liquor through adding thermal agitation 1 hour, along with the carrying out of hydrolysis and polymerisation, is formed the colloidal sol of black, sol liquid is positioned in 120 ℃ the drying box, obtain dry black gel; The dry black gel that obtains is put into Muffle furnace, carry out spontaneous combustion after 3 hours in insulation under 500 ℃ the temperature and handle, removing organic principle wherein, and obtain the nano-powder product of black loose powder shape.Prepared powder is made the sample of thick 1mm diameter 10mm under the pressure of 70Mpa, sintering formed fine and close polycrystalline ceramics thin slice in 4 hours in 1100 ℃ silicon carbide rod furnace then, with two the surface soldered lead-in wires of silver slurry to sample, adopt resin-encapsulate, obtain the NTC thermistor at last.After tested, 85 ℃ of resistance are 575 Ω cm, and 25 ℃ of resistance are 6130 Ω cm, and B25/85 constant (K) is 4211, and the relative resistance rate of change of placing 25 ℃ of resistance after 400 hours in 125 ℃ of environment is lower than 0.32%.
In the concrete experimentation, adopting the nitrate of Ni, Mn, Cr is raw material, utilizes combustion method of citric acid to make powder body material about 50 nanometers, pass through compressing tablet again, high temperature sintering, the silver slurry is to two surface soldered lead-in wires of resistance, seal, obtain the NTC thermistor at last.The example granular size of the thermo-sensitive material behind the sintering is about 1 micron (μ m).Final material is the spinel structure phase.
Claims (2)
1. nano-powder that is used to prepare high precision thermosensitive resistor, it is characterized in that it with the nitrate of Cr, Ni, Mn as raw material, add citric acid, polyethylene glycol and ammoniacal liquor, after adding thermal agitation, form vitreosol liquid through hydrolysis and polymerisation, will obtain after the sol liquid drying dry gel, the gel of drying carried out spontaneous combustion after, promptly obtain Powdered nano-powder product.
2. the nano-powder that is used to prepare high precision thermosensitive resistor as claimed in claim 1 is characterized in that it follows these steps to make:
A, take by weighing Cr, Ni, Mn respectively nitrate as raw material, its ratio is: Cr: Ni: Mn=5-15: 30: 55-65, mix and to dissolve in the deionized water, control metal ion molar concentration is: 0.1-0.4mol/L is configured to major constituent solution;
B, add citric acid and polyethylene glycol is made mixed liquor in the major constituent solution for preparing, regulate pH=3～5 of mixed liquor then with ammoniacal liquor, the molal quantity summation of metal ion is 1: 1.6～2.4 with the ratio of citric acid in mixed liquor;
C, with mixed liquor through adding thermal agitation 0.5～1 hour, through hydrolysis and polymerisation, form the vitreosol of pitchy, sol liquid is positioned in 120 ℃ the drying box, obtains dry gel after the dehydration;
The gel of d, the drying that will obtain is put into Muffle furnace, carries out spontaneous combustion after 2 hours in insulation under 450 ℃～500 ℃ the temperature and handles, and removing organic principle wherein, and obtains black loose powder shape nano-powder product.
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| CN105457661B (en) * | 2015-12-07 | 2018-05-25 | 天津医科大学 | A kind of method for preparing high-specific surface area chromium-based fluorination catalyst |
| CN107325119A (en) * | 2017-06-18 | 2017-11-07 | 天津大学 | A kind of method that complexing prepares yttrium colloidal sol |
| CN108723379B (en) * | 2018-07-23 | 2021-03-23 | 安徽工业大学 | Preparation method of multi-principal-element alloy nano powder |
| CN111872370B (en) * | 2020-07-15 | 2022-04-26 | 深圳市惠拓电子材料有限公司 | Preparation method of NTC thermistor material with ultrafine particle size |
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| JPS6456319A (en) * | 1987-08-28 | 1989-03-03 | Mitsubishi Metal Corp | Production of composite metal oxide powder |
| CN1636936A (en) * | 2004-12-03 | 2005-07-13 | 中国科学院长春应用化学研究所 | Prepn process of spinel type nanometer composite ferrite material |
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