CN1016505B - Graphite method for making porous ceramic humidity sensitive element - Google Patents
Graphite method for making porous ceramic humidity sensitive elementInfo
- Publication number
- CN1016505B CN1016505B CN 87101847 CN87101847A CN1016505B CN 1016505 B CN1016505 B CN 1016505B CN 87101847 CN87101847 CN 87101847 CN 87101847 A CN87101847 A CN 87101847A CN 1016505 B CN1016505 B CN 1016505B
- Authority
- CN
- China
- Prior art keywords
- graphite
- sensitive element
- humidity
- ceramic
- sintering
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 239000000919 ceramic Substances 0.000 title claims abstract description 41
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 title claims abstract description 40
- 229910002804 graphite Inorganic materials 0.000 title claims abstract description 37
- 239000010439 graphite Substances 0.000 title claims abstract description 37
- 238000000034 method Methods 0.000 title claims abstract description 12
- 238000005245 sintering Methods 0.000 claims abstract description 16
- 229910010293 ceramic material Inorganic materials 0.000 claims abstract description 3
- 239000000463 material Substances 0.000 claims description 11
- 238000000498 ball milling Methods 0.000 claims description 4
- 150000001875 compounds Chemical class 0.000 claims description 4
- 229910044991 metal oxide Inorganic materials 0.000 claims description 2
- 150000004706 metal oxides Chemical class 0.000 claims description 2
- 150000003839 salts Chemical class 0.000 claims description 2
- 238000005303 weighing Methods 0.000 claims description 2
- 238000001125 extrusion Methods 0.000 claims 1
- 238000004519 manufacturing process Methods 0.000 abstract description 9
- 230000035945 sensitivity Effects 0.000 abstract description 8
- 230000000694 effects Effects 0.000 abstract description 2
- 239000000126 substance Substances 0.000 abstract description 2
- 238000004140 cleaning Methods 0.000 abstract 1
- 238000010438 heat treatment Methods 0.000 abstract 1
- 239000011800 void material Substances 0.000 description 9
- 238000009826 distribution Methods 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 239000011148 porous material Substances 0.000 description 2
- 238000003860 storage Methods 0.000 description 2
- 238000011109 contamination Methods 0.000 description 1
- 238000009472 formulation Methods 0.000 description 1
- 238000013467 fragmentation Methods 0.000 description 1
- 238000006062 fragmentation reaction Methods 0.000 description 1
- 239000005338 frosted glass Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 229910052573 porcelain Inorganic materials 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 229910052723 transition metal Inorganic materials 0.000 description 1
- 150000003624 transition metals Chemical class 0.000 description 1
Images
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- Investigating Or Analyzing Materials By The Use Of Fluid Adsorption Or Reactions (AREA)
- Compositions Of Oxide Ceramics (AREA)
Abstract
The invention discloses a method for manufacturing a porous ceramic humidity sensitive element by adding graphite. Selection of 80CoO-20Co 0.7Fe1.3)O4The ceramic material is prepared into porous ceramic by adding graphite powder under constant forming pressure and sintering temperature. The porosity is 10-40%, and the amount of graphite added is 5-20 wt%, the optimum humidity sensitivity can be obtained. The ceramic humidity sensitive element has consistent mechanical, chemical and electrical properties, no need of heating and cleaning, high stability and long service life, and can obtain good effect when the graphite method is used for other formulas.
Description
The present invention relates to a kind of novel method of making the porous ceramics humidity-sensitive element, adopt the method that adds the graphite pore-forming material to make the porous ceramics humidity-sensitive element, this humidity-sensitive element is a kind of in order to measure the electronic component of humidity and controlling moisture.
The key of making humidity-sensitive element is the suitable porous ceramics gas cell distribution of structure, adopt now and reduce moulding pressure sintering porous ceramics (Sang Yuancheng: Port-ラ ス ptc material exploitation と characteristic, ユ レ ヮ ト ロ ニ ヮ セ ラ ミ ッ ワ ス, the 9-15 page or leaf, summer number, 1984), low, the easy fragmentation of its physical strength, and be not easy to obtain uniform ceramic gas cell distribution, the more important thing is that the resistivity and the specific inductivity of pottery is subjected to the influence of forming pressure and sintering temperature very big; Adopt the way agglomerating porous ceramics that reduces sintering temperature also to have same shortcoming.Become porcelain for the ease of pottery, when reducing forming pressure, need improve sintering temperature or add fusing assistant; Need increase forming pressure or add fusing assistant when reducing sintering temperature, these factors all can influence consistence and the stability that makes humidity-sensitive element, thereby the consistence of humidity-sensitive element and stability also fail to solve fully.
The objective of the invention is to propose a kind of new manufacture method, optimum sintering condition according to general pottery, employing adds the method for graphite pore-forming material, can obtain the porous ceramics of different void content easily, and machinery, chemistry, electric property are stablized, have good consistence and stability, the life-span is grown and is not needed heated wash.
Task of the present invention is finished by following program: mix with the determined various metal oxides of corresponding prescription, pre-burning then mixes pre-imitation frosted glass again with a certain amount of graphite, ball milling 2 hours, under constant forming pressure and sintering temperature, just can obtain porous ceramics.Making printing porous RuO on the wet body of porous ceramics sense at last
2Electrode, 800 ℃ of sintering just can obtain the ceramic moisture-sensitive element of stable performance.Feature of the present invention just in that volatilization obtains porous ceramics by graphite, adds the void content that how much determines porous ceramics and the gas cell distribution of graphite.This method that adds graphite pore-forming material manufacturing porous ceramics is all effective to multiple ceramic formula.
The present invention need not increase equipment, under constant forming pressure and sintering temperature, just can accurately control the void content and the pore size of porous ceramics as long as change content of graphite and graphite particle size, and add the resistivity and the specific inductivity of making pottery that how much do not influence of graphite.This porous ceramics that makes not only has identical mechanical and chemical property, and has consistent electric property.When adding quantity of graphite when being 5～20Wt%, can obtain the quick characteristic of optimal wet.Make humidity-sensitive element long lifetime, high stable and do not need heated wash.
Adopt following embodiment just to stablize and the good humidity-sensitive element of characteristic by manufacturing property:
CoO: Co in molar ratio
2O
3: Fe
2O
3=1: take by weighing three kind oxide compounds at 0.14: 0.26, thorough mixing, 1000～1100 ℃ of sintering of temperature 1～2 hour, 80CoO-20Co(C was synthesized in pre-burning
0.7Fe
1.3) O
4Ceramic material.Then with a certain amount of Graphite Powder 99 uniform mixing, ball milling 2 hours.The content of graphite is 0～50wt%, and granularity is 0.1～5 μ m.At 600～1000kg/cm
2Pressure depress to the ceramic disks of φ 8 * 1mm, at 1200～1400 ℃, 1～4 hour, sinter porous ceramics into.On ceramics, print RuO at last
2Electrode, burnt till the vesicular electrode in 15 minutes by 800 ℃.In order to reduce the influence of surface contamination, increase the life-span, adopt volume resistance to detect humidity.
Table 1 has provided the composition that content of graphite is 11 kinds of samples of 0～50wt%, average void content and to the sensitivity of humidity.
Temperature sensitivity α is defined as the ratio that relative humidity is respectively 10% and 100% actual measurement resistance value, promptly
α＝R
10%.R
100%
Wherein:
R
10% is the resistance value of relative humidity 10%RH;
R
100% is the resistance value of relative humidity 100%RH.
Below in conjunction with accompanying drawing invention is described in further detail;
Fig. 1 is the process flow sheet of production method of porous ceramic humidly-sensitive components by adding graphite.
Fig. 2 is average void content B of porous ceramics and the graph of a relation that adds graphite weight percent A.
Fig. 3 is the electricalresistivity and the graph of a relation that adds graphite weight percent A of porous ceramics.
Fig. 4 is porous ceramics humidity-sensitive element humidity sensitivity α and the graph of a relation that adds graphite weight percent A.
Fig. 5 is the sense wet electric resistance R of four kinds of samples and the graph of a relation of relative humidity φ.
Fig. 6 be No. 3 samples ceramic moisture-sensitive element sense wet electric resistance R and storage period t graph of a relation.
With reference to Fig. 1, the technical process of production method of porous ceramic humidly-sensitive components by adding graphite is simple.
Fig. 2 has shown the average void content B of porous ceramics and the relation that adds graphite weight percent A, pore-creating effect as can be seen; Along with the increase of graphite pore-forming material content, void content significantly increases, and under forming pressure that equates and sintering temperature, changes the content of graphite pore-forming material, just can obtain the porous ceramics of various void content easily.As the weight percent A≤20wt% that adds the graphite pore-forming material, void content increases very fast; When A＞20wt%, it is saturated that pore-creating is tending towards.
Fig. 3 is the electricalresistivity and the relation that adds graphite weight percent A of porous ceramic film material.Obviously, adopt the sintered porous pottery of this pore forming method, its resistivity is subjected to the influence of graphite pore-forming material hardly, has good consistence.
Fig. 4 represents the humidity sensitivity α and the relation that adds graphite weight percent A of production method of porous ceramic humidly-sensitive components by adding graphite.When not adding graphite (A=0), sensitivity α=2; After adding graphite, sensitivity α heightens, and can reach 20.The general excessive easy inefficacy of humidity sensitivity α, the resistance change scope is also wide.
Fig. 5 is respectively the sense wet electric resistance of No. 1, No. 2, No. 3 and No. 5 sample and the graph of a relation of relative humidity φ.Can be at 1～100%RH scope build-in test.Standard resistance range is 50～100K Ω among the figure, and in the low humidity situation of 10%RH, sense wet electric resistance value also is no more than 1M Ω, so adopt the simplest circuit just can assemble the hygrometric instrument.As we can see from the figure, No. 3 and No. 5 samples have the linear resistance humidity characteristic.Fig. 6 provided No. 3 samples ceramic moisture-sensitive element sense wet electric resistance R and storage period t graph of a relation.This humidity-sensitive element is a kind of heated wash, high stable and long-life ceramic moisture-sensitive element of not needing.
Total consideration graphite weight percent is the humidity-sensitive element that 5～20wt% can get the quick characteristic of optimal wet.
Adopt bases, the salt of transition metal to fill a prescription, as Co(OH)
2, Co(HCO
3)
3, FeCl
3Resolve into corresponding oxide compound CoO Deng high temperature, CO
2O
3, Fe
2O
3, can obtain and the corresponding to characteristic of above prescription.
The sintered porous pottery of graphite pore-forming material, multiple formulations is all effective, it is characterized in that the volatilization in sintering obtains porous ceramics by graphite.
Claims (2)
1, a kind of employing metal oxide through mixing, pre-burning, ball milling, extrusion forming and last sintering, and is made electrode thereon, makes the method for porous ceramics humidity-sensitive element, and feature is to select 80CoO-20Co (Co
0.7Fe
1.3) O
4Stupalith is made pore-forming material with graphite: in molar ratio, CoO: Co
2O
3: Fe
2O
3=1: take by weighing three kind oxide compounds at 0.14: 0.26, thorough mixing, temperature 1000-1100 ℃ sintering 1-2 hour, 80CoO-20Co (Co is synthesized in pre-burning
0.7Fe
1.3) O
4Ceramic material; Then with a certain amount of Graphite Powder 99 uniform mixing, ball milling 2 hours; Content of graphite is 5～50wt%, granularity 0.1-5 μ m; At 600-1000kg/cm
2Pressure depress to the ceramic disks of Φ 8 * 1mm; At temperature 1200-1400 ℃, 1-4 hour, sinter porous ceramics into; At last on the ceramics that burns till, print RuO
2Electrode, burnt till porous electrode in 15 minutes by 800 ℃.
2, by the described method of claim 1, it is characterized in that CoO in molar ratio: Co
2O
3: Fe
2O
3=1: the basic recipe of 014: 0.26 sintering humidity-sensitive element, wherein three kinds of oxide compounds are with corresponding bases, salt: Co(OH)
2, Co(HCO
3)
3, FeCl
3Replace.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 87101847 CN1016505B (en) | 1987-03-09 | 1987-03-09 | Graphite method for making porous ceramic humidity sensitive element |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 87101847 CN1016505B (en) | 1987-03-09 | 1987-03-09 | Graphite method for making porous ceramic humidity sensitive element |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN87101847A CN87101847A (en) | 1988-09-21 |
| CN1016505B true CN1016505B (en) | 1992-05-06 |
Family
ID=4813656
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 87101847 Expired CN1016505B (en) | 1987-03-09 | 1987-03-09 | Graphite method for making porous ceramic humidity sensitive element |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN1016505B (en) |
-
1987
- 1987-03-09 CN CN 87101847 patent/CN1016505B/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| CN87101847A (en) | 1988-09-21 |
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