CN101139205A - Heat treating method for improving evenness of negative temperature coefficient heat-sensitive material - Google Patents
Heat treating method for improving evenness of negative temperature coefficient heat-sensitive material Download PDFInfo
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- CN101139205A CN101139205A CNA2007100256446A CN200710025644A CN101139205A CN 101139205 A CN101139205 A CN 101139205A CN A2007100256446 A CNA2007100256446 A CN A2007100256446A CN 200710025644 A CN200710025644 A CN 200710025644A CN 101139205 A CN101139205 A CN 101139205A
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Abstract
The present invention discloses a heat treatment method for improving evenness for the negative-temperature coefficient heat-sensing material, which is characterized in that: the negative temperature coefficient heat sensing resistance ceramic materials after being agglomerated is to be cut into a slice with the thickness of 0.2-0.5mm; and then with the temperature increasing speed of 3-10 DEG C /min, the temperature is to be raised to the agglomerating temperature, and then the slice is kept in the temperature for 5-10 hours; and then the temperature for the slice is cooled into the room temperature with the furnace. By using of the heat treatment method in the present invention, the unevenness for the ceramic materials in the agglomerating process can be decreased effectively. Compared with the ceramic slice without any heat treatment, the finished product ratio for the heat sensing resistance by the ceramic slice made with the heat treatment in the present invention within plus or minus 1 percent of the resistance value can be enhanced greatly.
Description
Technical field:
The invention belongs to the negative temperature coefficient thermistor composition technical field, particularly improve the inhomogeneity heat treating method of negative temperature coefficient thermistor composition.
Background technology:
In recent years, along with science and technology development, require negative temperature coefficient (NTC) thermistor element to have high precision, high reliability to improving constantly of thermometric and temperature-controlled precision.So-called high precision NTC thermistor element, the deviation of its resistance and B value should be controlled at ± 1% in, and should have secular stability and interchangeability.Disclose according to Chinese patent CN1588574A, the briquetting sintering still is the common processing step during present domestic NTC thermistor is produced." electronic original part and material " (22,14-16,2003) reported in the briquetting sintering process, owing to be to carry out the gradient type heating by heat conducting mode ecto-entad, and ceramic block actual oxygen dividing potential drop difference outer and core is bigger, the skin and the core that cause pottery have than marked difference on composition and microstructure, and the ununiformity of NTC thermo-sensitive material has caused resistivity radially or vertically to distribute, and causes the qualification rate of the finished product very low.
Therefore seeking novel method that technology simply and effectively improves the even type of thermo-sensitive material becomes and is even more important.
Summary of the invention:
The present invention proposes the inhomogeneity heat treating method of a kind of improvement negative temperature coefficient thermistor composition, thereby has marked difference to cause the low problem of the finished product qualification rate to overcome existing caused top ceramic layer of briquetting sintering process and core on composition and microstructure.
The present invention improves the inhomogeneity heat treating method of negative temperature coefficient thermistor composition, comprises adopting solid state reaction or coprecipitation method at 750-850 ℃ of calcining preparation negative temperature coefficient thermosensitive ceramics powder earlier; With the powder moulding, make green compact in the 200-300MPa isostatic cool pressing; Heat-up rate with 3-10 ℃/min is heated to sintering temperature then, insulation 5-10h, furnace cooling; It is characterized in that preparation-obtained negative tempperature coefficient thermistor stupalith is cut into the thin slice that thickness is 0.2-0.5mm, be heated to sintering temperature, and, cool to room temperature again with the furnace at this temperature insulation 5-10h with the heat-up rate of 3-10 ℃/min.
In order to prevent that the thermistor ceramic sheet from high temperature curling, and can be pressed in ceramic sheet between the porous ceramic plate and heat-treat.
Compared with prior art, because the present invention cuts into the thin slice that thickness is 0.2-0.5mm with the negative tempperature coefficient thermistor stupalith, heat-up rate with 3-10 ℃/min is heated to sintering temperature and is incubated 5-10h, the thermal treatment process that adopts the mode of furnace cooling to lower the temperature again, the edge of ceramic sheet is near identical outside atmosphere with inner, top ceramic layer and the difference of core on composition and microstructure that causes in the briquetting sintering process can be eliminated in heat treatment process, help improving the homogeneity of stupalith.Do not compare with passing through heat treated ceramic plate, the thermistor element resistance that the ceramic plate after adopting the inventive method thermal treatment makes improves with interior yield rate greatly ± 1%.
Embodiment:
The following specifically describes the embodiment that adopts the inventive method to improve the inhomogeneity thermal treatment process of negative temperature coefficient thermistor composition gives an example.
Embodiment 1: to Ni
0.75Mn
1.38Al
0.87O
4Thermo-sensitive material is heat-treated
Used Ni in the present embodiment
0.75Mn
1.38Al
0.87O
4The compound oxalate calcining that powder utilizes the room temperature solid state reaction to generate obtains: utilize analytical balance accurately to take by weighing nickelous acetate 186.63g, manganous acetate 338.22, plumbous subacetate 326.19, oxalic acid 453.85g, above-mentioned miscellany is carried out ball milling mixing 20h, obtain compound oxalate, 70 ℃ of oven dry; Under fluidizing air atmosphere,, obtain Ni at 850 ℃ of calcining 4h
0.75Mn
1.38Al
0.87O
4Powder; Adopt that the metallic element ratio is Ni: Mn: Al=0.75 in the powder after inductively coupled plasma atomic emission spectrometry (ICP) is measured this calcining: 1.38: 0.87; Under pressure is the isostatic cool pressing of 300MPa the pressed by powder that makes being become diameter then is 4cm, highly is the right cylinder of 4.5cm; Rate of heating with 10 ℃/min is warmed up to 1250 ℃ of sintering temperatures then, and at 1250 ℃ of insulation 10h, furnace cooling makes Ni then
0.75Mn
1.38Al
0.87O
4Ceramic block; Utilize slicing machine that ceramic block is cut into the disk of thickness for 0.2mm; Take out 10 at random, be warmed up to 1250 ℃ of sintering temperatures, then at 1250 ℃ of insulation 10h with the rate of heating of 10 ℃/min; In order to prevent thin slice curling at high temperature, thin slice can be pressed between the porous ceramic plate during thermal treatment and carry out; Adopt the mode of furnace cooling to be cooled to 25 ℃ of room temperatures again; To smear electrode through the mode of ceramic plate after the above-mentioned thermal treatment and the not heat treated ceramic plate of process two sides employing silk screen printing, at 850 ℃ of burning infiltration electrodes; Utilize scribing machine to be cut into the square sheet of 0.5mm * 0.5mm size then, obtain being of a size of the NTC thermistance element of 0.5mm * 0.5mm * 0.2mm.
100 NTC thermistance elements that obtain with this method are selected in random sampling, measure their resistance values in the time of 25 ℃ respectively, and without heat treated Ni
0.75Mn
1.38Al
0.87O
4The components and parts of ceramic sheet are compared, without heat treated Ni
0.75Mn
1.38Al
0.87O
4Ceramic sheet components and parts resistance is 25.3% ± 1% with interior qualification rate, and be 45.2% ± 1% with interior qualification rate through adopting the ceramic sheet components and parts resistance of the inventive method after 1250 ℃ of thermal treatment, promptly resistance has improved 0.8 times ± 1% with interior qualification rate.This shows, can improve Ni the thermal treatment of ceramic sheet
0.75Mn
1.38Al
0.87O
4The homogeneity of NTC thermo-sensitive material and consistence.
Embodiment 2: to Co
0.94Mn
0.94Ni
0.94Fe
0.18O
4Thermo-sensitive material is heat-treated
Present embodiment adopts coprecipitation method to prepare powder: with Xiao Suangu, manganous nitrate, nickelous nitrate and iron nitrate according to 0.94: 0.94: 0.94: 0.18 mol ratio is made into the aqueous solution of 0.5mol/L, with ammoniacal liquor this solution is transferred to pH=7, then filtering precipitate; For preventing the reunion of powder, can utilize ethanol to wash powder twice; This powder 80 ℃ of oven dry, is calcined 4h at 750 ℃; Being that to be pressed into diameter under the isostatic cool pressing pressure of 200MPa be 5cm at pressure with the powder that makes, highly is the right cylinder of 6cm; Speed with 3 ℃/min heats to 1200 ℃ of sintering temperatures then, and at 1200 ℃ of insulation 5h, cools to 25 ℃ of room temperatures then with the furnace, obtains Co
0.94Mn
0.94Ni
0.94Fe
0.18O
4Ceramic block; Utilize slicing machine that ceramic block is cut into the disk of thickness for 0.5mm; Take out 10 at random, be warmed up to 1200 ℃ of sintering temperatures with the rate of heating of 3 ℃/min, and at 1200 ℃ of insulation 5h; In order to prevent thin slice curling at high temperature, thin slice can be pressed between the porous ceramic plate during thermal treatment; Adopt the mode of furnace cooling to be cooled to 25 ℃ of room temperatures again; To smear electrode through the mode of ceramic plate after the above-mentioned thermal treatment and the not heat treated ceramic plate of process two sides employing silk screen printing, at 850 ℃ of burning infiltration electrodes; Utilize scribing machine to be cut into the square sheet of 0.5mm * 0.5mm size then, obtain being of a size of the NTC thermistance element of 0.5mm * 0.5mm * 0.5mm.
Random sampling is selected 100 and is measured their resistance values in the time of 25 ℃ through adopting the inventive method at 1200 ℃ of heat treated negative tempperature coefficient thermistor components and parts, and without heat treated Co
0.94Mn
0.94Ni
0.94Fe
0.18O
4The components and parts of ceramic sheet are compared, without heat treated Co
0.94Mn
0.94Ni
0.94Fe
0.18O
4The components and parts resistance that ceramic sheet obtains only is 5.9% ± 1% with interior qualification rate, and be 52.6% ± 1% with interior qualification rate through adopting the ceramic sheet components and parts resistance of the inventive method after 1200 ℃ of thermal treatment, promptly resistance has improved 8 times ± 1% with interior qualification rate.This shows, the thermal treatment of ceramic sheet has been improved Co greatly
0.94Mn
0.94Ni
0.94Fe
0.18O
4The homogeneity of NTC thermo-sensitive material and consistence.
Embodiment 3: to Mn
1.84Ni
0.66Fe
0.5O
4Thermo-sensitive material is heat-treated
Present embodiment adopts coprecipitation method to prepare powder: manganous nitrate, nickelous nitrate and iron nitrate are made into the aqueous solution of 0.5mol/L according to 1.84: 0.66: 0.5 mol ratio, utilize ammoniacal liquor that this solution is transferred to pH=7, then filtering precipitate; For preventing the reunion of powder, can utilize ethanol to wash powder twice; This powder 80 ℃ of oven dry, is calcined 4h at 800 ℃; Being that to be pressed into diameter under the isostatic cool pressing pressure of 300MPa be 4cm then at pressure with the powder that makes, highly is the right cylinder of 5cm; Speed with 5 ℃/min heats to 1200 ℃ of sintering temperatures then, and at 1200 ℃ of insulation 5h, cools to 25 ℃ of room temperatures then with the furnace, obtains Mn
1.84Ni
0.66Fe
0.5O
4Ceramic block; Utilize slicing machine that ceramic block is cut into the disk of thickness for 0.25mm; Take out 10 at random, be warmed up to 1200 ℃ of sintering temperatures with the rate of heating of 5 ℃/min, and at 1200 ℃ of insulation 5h; In order to prevent thin slice curling at high temperature, thin slice can be pressed between the porous ceramic plate and heat-treat; Adopt the mode of furnace cooling to be cooled to 25 ℃ of room temperatures again; To smear electrode through the mode of ceramic plate after the above-mentioned thermal treatment and the not heat treated ceramic plate of process two sides employing silk screen printing, at 850 ℃ of burning infiltration electrodes; Utilize scribing machine to be cut into the square sheet of 0.5mm * 0.5mm size then, obtain being of a size of the NTC thermistance element of 0.5mm * 0.5mm * 0.25mm.
Random sampling is selected 100 and is measured their resistance values in the time of 25 ℃ through adopting the inventive method at 1200 ℃ of heat treated negative tempperature coefficient thermistor components and parts, and without heat treated Mn
1.84Ni
0.66Fe
0.5O
4The ceramic sheet components and parts are compared, without heat treated Mn
1.84Ni
0.66Fe
0.5O
4Ceramic sheet components and parts resistance is 13% ± 1% with interior qualification rate, and be 52% ± 1% with interior qualification rate through adopting the ceramic sheet components and parts resistance of the inventive method after 1200 ℃ of thermal treatment, promptly resistance has improved 3 times ± 1% with interior qualification rate.This shows, the thermal treatment of ceramic sheet has been improved Mn greatly
1.84Ni
0.66Fe
0.5O
4The homogeneity of NTC thermo-sensitive material and consistence.
Claims (2)
1. one kind is improved the inhomogeneity heat treating method of negative temperature coefficient thermistor composition, comprises adopting solid state reaction or coprecipitation method at 750-850 ℃ of calcining preparation negative temperature coefficient thermosensitive ceramics powder earlier; With the powder moulding, make green compact in the 200-300MPa isostatic cool pressing; Heat-up rate with 3-10 ℃/min is heated to sintering temperature then, and at this temperature insulation 5-10h, furnace cooling; It is characterized in that: preparation-obtained negative tempperature coefficient thermistor stupalith is cut into the thin slice that thickness is 0.2-0.5mm, be heated to sintering temperature, and, cool to room temperature again with the furnace at this temperature insulation 5-10h with the heat-up rate of 3-10 ℃/min.
2. improve the inhomogeneity heat treating method of negative temperature coefficient thermistor composition according to claim 1, be characterised in that in the heat treatment process ceramic sheet is pressed between the porous ceramic plate and carry out.
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| CNA2007100256446A CN101139205A (en) | 2007-08-10 | 2007-08-10 | Heat treating method for improving evenness of negative temperature coefficient heat-sensitive material |
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|---|---|---|---|
| CNA2007100256446A CN101139205A (en) | 2007-08-10 | 2007-08-10 | Heat treating method for improving evenness of negative temperature coefficient heat-sensitive material |
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101719404B (en) * | 2009-12-28 | 2011-03-16 | 中国科学院新疆理化技术研究所 | Ternary-system chip negative temperature coefficient thermal resistor |
| CN102674826A (en) * | 2012-06-05 | 2012-09-19 | 安徽建筑工业学院 | Low-resistivity high-B-value negative temperature coefficient heat-sensitive ceramic material and preparation process thereof |
| CN103387381A (en) * | 2013-07-03 | 2013-11-13 | 上海工程技术大学 | Medium-high-temperature NTC thermistor material, preparation method and application |
| CN111320469A (en) * | 2020-02-24 | 2020-06-23 | 广州新莱福磁电有限公司 | Manufacturing method of NTC thermistor material |
| CN112802648A (en) * | 2021-01-12 | 2021-05-14 | 中国科学院新疆理化技术研究所 | Thermistor based on high-entropy oxide and preparation method thereof |
| CN114716232A (en) * | 2022-04-28 | 2022-07-08 | 华南理工大学 | Method for improving high-precision yield of NTC product |
-
2007
- 2007-08-10 CN CNA2007100256446A patent/CN101139205A/en active Pending
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101719404B (en) * | 2009-12-28 | 2011-03-16 | 中国科学院新疆理化技术研究所 | Ternary-system chip negative temperature coefficient thermal resistor |
| CN102674826A (en) * | 2012-06-05 | 2012-09-19 | 安徽建筑工业学院 | Low-resistivity high-B-value negative temperature coefficient heat-sensitive ceramic material and preparation process thereof |
| CN102674826B (en) * | 2012-06-05 | 2013-08-14 | 安徽建筑工业学院 | Low-resistivity high-B-value negative temperature coefficient heat-sensitive ceramic material and preparation process thereof |
| CN103387381A (en) * | 2013-07-03 | 2013-11-13 | 上海工程技术大学 | Medium-high-temperature NTC thermistor material, preparation method and application |
| CN111320469A (en) * | 2020-02-24 | 2020-06-23 | 广州新莱福磁电有限公司 | Manufacturing method of NTC thermistor material |
| CN112802648A (en) * | 2021-01-12 | 2021-05-14 | 中国科学院新疆理化技术研究所 | Thermistor based on high-entropy oxide and preparation method thereof |
| CN114716232A (en) * | 2022-04-28 | 2022-07-08 | 华南理工大学 | Method for improving high-precision yield of NTC product |
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