CN101303322B - Surface modification method of WO3 thick film gas-sensitive sensor - Google Patents
Surface modification method of WO3 thick film gas-sensitive sensor Download PDFInfo
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- CN101303322B CN101303322B CN2008101163015A CN200810116301A CN101303322B CN 101303322 B CN101303322 B CN 101303322B CN 2008101163015 A CN2008101163015 A CN 2008101163015A CN 200810116301 A CN200810116301 A CN 200810116301A CN 101303322 B CN101303322 B CN 101303322B
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Abstract
A surface modification method of a WO3 thick film gas-sensitive sensor belongs to the technique field of the gas-sensitive sensor. The method includes decompounding the tungstenic acid after heat preserving for two hours under the temperature of 400-800 EDG C; adding adhesive in a WO3 powder to prepare a sensitive material slurry; printing the slurry on the aluminum oxide substrate provided within terdigital silver electrodes and silver electrode lead wires, heat preserving and sintering in the air to prepare a WO3 thick film gas-sensitive sensor; firstly heat preserving the prepared WO3 thick film gas-sensitive sensor in H2 atmosphere, and then heat preserving in the air, so that a modified WO3 thick film gas-sensitive sensor is prepared. The invention has advantages of low cost, simple steps, short response recovery time, important practical application value, easily controllable processing parameters in the preparing process, and small energy sources consumption in the entire preparing process; and the WO3 thick film gas-sensitive sensor after surface modification has capability of realizing high sensibility detection to the 1-200ppm CO.
Description
Technical field
The present invention relates to a kind of WO
3The surface modifying method of thick film gas-sensitive sensor belongs to the gas sensor technical field.
Background technology
After the conductivity of cuprous oxide in 1931 changed this characteristic with the absorption of water vapour and is found, people began the gas-sensitive property of some material has been carried out extensive and deep research.In recent years, the metal oxide gas sensor of having succeeded in developing is widely used in the detection of gases such as various toxic and harmfuls, inflammable gas, industrial gaseous waste, environmental pollution with its higher sensitivity and selectivity, good response and recovery characteristics and long serviceable life.
Tungsten oxide is a kind of transition metal oxide n N-type semiconductor N, WO
3The research of base gas sensitive starts from phase early 1990s, and in oxide semiconductor gas sensor application, at present, the tungsten oxide sill has been considered to detect NO
x, SO
x, NH
3, H
2One of the most promising new oxide gas sensitive such as S.Because the surface modification technology of the sensitivity of Metal Oxide Semiconductor Gas Sensing sensor and the preparation method of selectivity and matrix material and sensitive membrane is closely related.In recent years, most studies concentrates on different deposition parameters to WO
3The influence of microstructure, surface topography and corresponding air-sensitive performance of base gas sensitive, as different parameters such as oxygen bias voltage, substrate temperature, annealing temperatures to WO
3The influence of the microstructure of air-sensitive film, surface topography, air-sensitive performance etc. (1. M.Stankova et al.Sens.Actuators B, 103:23～30,2004; 2. M.Stankova et al.Sensors and Actuators B, 113:241～248,2006; 3. Viacheslav Khatko et al.Sensors and Actuators B, 118:255～262,2006).Yet, in the preparation process of air-sensitive film, the equipment needed thereby costliness, preparation technology and complexity thereof realize that the difficulty of large-scale production is very big.
The research of present most of tungsten oxide based sensors mainly concentrates in the research of the polycrystalline film of being made up of big crystallite dimension, owing to be subjected to the restriction of surface structure and crystallite dimension, the sensitivity and the selectivity of sensor are not ideal enough, could obtain high sensitivity and repeatability when having only the probe temperature of raising or passing through to mix other material.The present invention prepares WO by decomposing wolframic acid under the prerequisite that has overcome above-mentioned deficiency
3Powder, adopt then serigraphy the method success preparation WO
3Thick film gas-sensitive sensor, and adopt the atmosphere modification technique that sensitive membrane is modified, thus realized highly sensitive detection to CO.
Summary of the invention
Exist in the research at present most of tungsten oxide based sensors such as: equipment needed thereby costliness, preparation technology are extremely complicated, realize problems such as the difficulty of large-scale production is very big.The objective of the invention is to overcome the deficiencies in the prior art part, provide a kind of with low cost, preparation method simple, to the extremely sensitive WO of low concentration CO
3The surface modifying method of thick film gas-sensitive sensor, this has crucial value and realistic meaning in the gas sensor field.
WO described in the present invention
3The surface modifying method of thick film gas-sensitive sensor may further comprise the steps:
(1) under 400～800 ℃ temperature, is incubated 2 hours wolframic acid is decomposed preparation WO
3Powder;
(2) with the WO in above-mentioned (1)
3Powder is a material of main part, is bonding agent with ethyl cellulose, terpinol and ethyl orthosilicate, above-mentioned material is mixed in proportion and stir after promptly make sensitive material slurry.
(3) adopt the method for serigraphy the slurry in above-mentioned (2) to be printed on the aluminum oxide substrate that interdigital silver electrode and silver electrode lead wires are arranged, in air, be prepared into WO behind the sintering in 1～2 hour through 600～800 ℃ of insulations
3Thick film gas-sensitive sensor;
(4) sample in above-mentioned (3) is first at H
2Reduce processing in 0.5 hour in 600～800 ℃ of insulations in the atmosphere, then it is incubated 0.5 hour in 500～700 ℃ air and carries out oxidation processes, promptly make the WO after the modification
3Thick film gas-sensitive sensor.
Heating rate is 2 ℃/minute in the described step (1), makes sintering furnace reduce to room temperature naturally in the maximum temperature insulation after 2 hours.
Elder generation is with WO described method is prepared slip in step (2) before
3Powder is crossed 500 purposes sieve, and incites somebody to action load weighted WO in proportion
3Powder and various cementing agent carried out magnetic agitation 20 hours so that make the sensitive material slurry with certain viscosity and good fluidity.
The length of described aluminum oxide substrate is 21mm, and wide is 15mm, and thickness is 0.6mm, and the synoptic diagram of its electrode and slip respectively as depicted in figs. 1 and 2; The aluminum oxide substrate that prints behind the slip needs carry out abundant drying in 80 ℃ air; Heating rate in the follow-up sintering process is 2 ℃/minute, makes sintering furnace reduce to room temperature naturally in the maximum temperature insulation after 1 hour.
H in the described method step (4)
2Concentration (balance gas is N
2) be 5% or 10%, at H
2In the heating rate in when reduction be 2 ℃/minute, the heating rate of oxidation is respectively 2.5 ℃/minute, 5 ℃/minute or 10 ℃/minute in air.
Advantage of the present invention and good effect are: with low cost, preparation method and preparation process are very simple, technological parameter in the preparation process is controlled easily, the energy resource consumption of whole process of preparation is considerably less, can realize highly sensitive detection to the CO of 1～200ppm in the environment to be measured, and response recovery time is short, has important application value.
Description of drawings
Fig. 1 is the synoptic diagram of interdigital silver electrode on the aluminum oxide substrate.
Fig. 2 is the synoptic diagram of printing slurry on the aluminum oxide substrate.
The thermogravimetric analysis curve synoptic diagram that Fig. 3 decomposes for wolframic acid.
Fig. 4 is through 500 ℃ of sintering gained WO after 2 hours with wolframic acid
3The stereoscan photograph of powder.
Fig. 5 is WO
3Thick film is through the stereoscan photograph of 700 ℃ of sintering after 1 hour.
Fig. 6 is WO behind the sintering in 700 ℃ of air
3Thick film sensor is to the sensitivity test result schematic diagram of CO.
Figure 72 be earlier through 700 ℃ of reduction after WO after 600 ℃ of oxidations
3The stereoscan photograph of sensitive membrane.
Fig. 8 is through 5%H
2WO after the modification
3Thick film gas-sensitive sensor when 350 ℃ and 450 ℃ sensitivity with the variation relation synoptic diagram of CO concentration.
Fig. 9 is through 10%H
2WO after the modification
3Thick film gas-sensitive sensor when 400 ℃ and 450 ℃ sensitivity with the variation relation synoptic diagram of CO concentration.
Embodiment
Further specify the present invention below in conjunction with embodiment.
Embodiment one:
In the present embodiment, decompose preparation WO by wolframic acid
3Powder and preparation slip method described with the summary of the invention part, Fig. 3 is the thermogravimetric analysis curve that wolframic acid decomposes, as seen from Figure 3, wolframic acid is just fully weightless in the time of 400 ℃, because the too high meeting of decomposition temperature causes WO
3The activity of powder reduces, so, the used WO of preparation slip in the present embodiment
3Powder is wolframic acid decomposes gained in the time of 500 ℃ a product, and its stereoscan photograph as shown in Figure 4.The WO that wolframic acid is decomposed gained 500 ℃ the time
3Powder is by the described slip that is mixed with of summary of the invention part, adopt serigraphy to get method then and be prepared into sensitive membrane, with this sensitive membrane with 2 ℃/minute heating rate 700 ℃ the time insulation after 1 hour the gained sensitive membrane form by the tungsten oxide particle of almost spherical, its stereoscan photograph is as shown in Figure 5.This WO
3Thick film gas-sensitive sensor when 400 ℃ and 450 ℃ to the sensitivity test result of CO as shown in Figure 6.As seen from Figure 6, its sensitivity of increase with CO concentration is the linear trend that increases substantially, and, along with this thick film sensor of rising of probe temperature is remarkable to the increasing degree of CO sensitivity, as being during at 400 ℃ 2.6 times 450 ℃ the time to the sensitivity of 142ppmCO.
With above-mentioned WO
3Thick film sensor carries out surface modification treatment, and concrete grammar is, with 2.5 ℃/minute heating rates at 5% H
2Reduced in 0.5 hour in 700 ℃ of insulations in the atmosphere and handle and reduce to naturally room temperature, with 2.5 ℃/minute heating rate it is incubated 0.5 hour and carries out oxidation processes in 600 ℃ air then and also reduce to room temperature naturally, promptly make the WO after the modification
3Thick film gas-sensitive sensor, its stereoscan photograph as shown in Figure 7, as seen from Figure 7, WO after surface modification
3Sensitive membrane is become the club shaped structure of both ends open by the particle of almost spherical.This WO
3Thick film gas-sensitive sensor when 350 ℃ and 450 ℃ to the sensitivity test result of CO as shown in Figure 8.As seen from Figure 8, its sensitivity of increase with CO concentration is the linear trend that increases substantially, and, along with this thick film sensor of rising of probe temperature is remarkable to the increasing degree of CO sensitivity, as being during at 350 ℃ 43 times 450 ℃ the time to the sensitivity of 95ppmCO.Simultaneously, comparison diagram 7 and Fig. 8 we as can be seen, through WO after the surface modification
3The sensitivity of thick film gas-sensitive sensor has had and has increased substantially, as 2 times before the sensitivity of 142ppmCO being modification 450 ℃ the time.
Embodiment two:
In the present embodiment, the step of being implemented is identical with embodiment one, and different is: to WO
3When thick film sensor carried out surface modification treatment, concrete grammar was, with 2.5 ℃/minute heating rates at 10% H
2Reduced in 0.5 hour in 700 ℃ of insulations in the atmosphere and handle and reduce to naturally room temperature, with 2.5 ℃/minute heating rate it is incubated 0.5 hour and carries out oxidation processes in 600 ℃ air then and also reduce to room temperature naturally, promptly make the WO after the modification
3Thick film gas-sensitive sensor.This WO
3Thick film gas-sensitive sensor when 400 ℃ and 450 ℃ to the sensitivity test result of CO as shown in Figure 9.As seen from Figure 9, its sensitivity of increase with CO concentration is the linear trend that increases substantially, and, along with this thick film sensor of rising of probe temperature is remarkable to the increasing degree of CO sensitivity, as being during at 400 ℃ 3.5 times 450 ℃ the time to the sensitivity of 24ppmCO.Simultaneously, comparison diagram 7 and Fig. 9 we as can be seen, through 10%H
2WO after the surface modification
3The sensitivity of thick film gas-sensitive sensor has had and has increased substantially, as 6 times and 15 times before the sensitivity of 38ppmCO being modification respectively when 400 ℃ and 450 ℃.
Embodiment three to embodiment ten:
In embodiment three to embodiment ten, the step of being implemented is identical with embodiment one, and different is: dried WO
3Sensitive membrane at first will be incubated 1～2 hour respectively in 600 and 800 ℃ air atmosphere carries out sintering, then respectively at 600 and 800 ℃ H
2The H that is adopted was handled in reduction 0.5 hour under the atmosphere under each reduction temperature
2Concentration difference 5% and 10%.WO after at last 600 ℃ of reduction being handled
3Sensitive membrane in air under 500 ℃ temperature oxidation processes 0.5 hour, the oxidation heating rate is respectively 2.5 ℃/minute, 5 ℃/minute and 10 ℃/minute in this process, and this sensitive membrane range of sensitivity to 1～200ppmCO under 350～450 ℃ probe temperature is 0.8～216.With the WO after 800 ℃ of reduction processing
3Sensitive membrane in air under 700 ℃ temperature oxidation processes 0.5 hour, the oxidation heating rate is respectively 2.5 ℃/minute, 5 ℃/minute and 10 ℃/minute in this process, and this sensitive membrane range of sensitivity to 1～200ppmCO under 350～450 ℃ probe temperature is 1.1～240.The specific embodiment of above-mentioned method of modifying is as shown in table 1.
Table 1 WO
3The specific embodiment of thick film sensor surface modification
From above all embodiment as can be seen, as long as various parameters within the limits prescribed in the assurance preparation process, then the sensitivity to CO will be greatly improved through sensitive membrane after the modification.Decomposition temperature when preparing the tungsten oxide powder as the wolframic acid decomposition method is in 400～800 ℃, and reason is if the too high activity that then will cause decomposing the tungsten oxide of gained of decomposition temperature reduces, and further will reduce its air-sensitive performance.Tungsten oxides with 500 ℃ of decomposition wolframic acid gained among the present invention are example, to prepared WO
3Thick film sensor has carried out Research on Surface Modification, and the result shows, through the sensitive membrane after the surface modification in 350～450 ℃ of scopes to the response recovery time of 1～200ppmCO all less than 30 seconds.In concrete implementation process, decomposing the prepared tungsten oxide of wolframic acid with 400～800 ℃ is the surface modification effect that research object still can reach expection.Those skilled in the art can both carry out concrete enforcement according to the specialized range of each technological parameter, does not exceed with the given the foregoing description of the present invention.
More than by specific embodiment the present invention is described in detail, those skilled in the art are to be understood that, in the scope that does not exceed spirit of the present invention and essence, certain modification and distortion that the present invention is made, still can realize result of the present invention, and not exceed scope of the present invention.
Claims (2)
1.WO
3The surface modifying method of thick film gas-sensitive sensor is characterized in that, this method may further comprise the steps:
(1) under 400～800 ℃ temperature, is incubated 2 hours wolframic acid is decomposed preparation WO
3Powder;
(2) WO that makes toward step (1)
3Add bonding agent in the powder, after stirring, promptly make sensitive material slurry;
Described bonding agent is ethyl cellulose, terpinol and ethyl orthosilicate;
(3) adopt the method for serigraphy the slurry in above-mentioned (2) to be printed on the aluminum oxide substrate that interdigital silver electrode and silver electrode lead wires are arranged, in air, be prepared into WO behind the sintering in 1～2 hour through 600～800 ℃ of insulations
3Thick film gas-sensitive sensor;
(4) with the WO that makes in the step (3)
3Thick film gas-sensitive sensor is earlier at H
2Reduce processing in 0.5 hour in 600～800 ℃ of insulations in the atmosphere, then it is incubated 0.5 hour in 500～700 ℃ air and carries out oxidation processes, promptly make the WO after the modification
3Thick film gas-sensitive sensor.
2. WO according to claim 1
3The surface modifying method of thick film gas-sensitive sensor is characterized in that, described H
2Concentration be 5% or 10%.
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| CN101303322B true CN101303322B (en) | 2011-07-27 |
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| CN104792830B (en) * | 2015-05-15 | 2017-06-16 | 哈尔滨工业大学 | The preparation method of the gas sensitive material being combined based on Graphene/molybdenum bisuphide |
| CN111646705A (en) * | 2017-04-24 | 2020-09-11 | 揭阳市宏光镀膜玻璃有限公司 | Preparation method of nanostructure electrochromic film |
| CN108195894B (en) * | 2017-12-26 | 2021-01-15 | 桂林理工大学 | Gas-sensitive coating for monitoring CO and NO2 contents in tail gas of alcohol-based fuel and preparation method thereof |
| CN110231372B (en) * | 2019-07-17 | 2021-08-03 | 上海海事大学 | Gas sensor for acetone detection and preparation method thereof |
| CN110646474A (en) * | 2019-10-25 | 2020-01-03 | 中北大学 | Based on WO3Wireless passive H2Gas sensor and preparation method thereof |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4397888A (en) * | 1981-01-14 | 1983-08-09 | Westinghouse Electric Corp. | Thick film sensor for hydrogen and carbon monoxide |
| CN1445536A (en) * | 2002-03-14 | 2003-10-01 | 财团法人工业技术研究院 | Method for synthesizing predecessor of tungsten trioxide and hydrogen sulfide gas sensor made from the predecessor |
| CN1975397A (en) * | 2006-12-21 | 2007-06-06 | 天津大学 | Tungstic acid thin film air-sensitive sensor surface modifying method |
-
2008
- 2008-07-08 CN CN2008101163015A patent/CN101303322B/en not_active Expired - Fee Related
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4397888A (en) * | 1981-01-14 | 1983-08-09 | Westinghouse Electric Corp. | Thick film sensor for hydrogen and carbon monoxide |
| CN1445536A (en) * | 2002-03-14 | 2003-10-01 | 财团法人工业技术研究院 | Method for synthesizing predecessor of tungsten trioxide and hydrogen sulfide gas sensor made from the predecessor |
| CN1975397A (en) * | 2006-12-21 | 2007-06-06 | 天津大学 | Tungstic acid thin film air-sensitive sensor surface modifying method |
Non-Patent Citations (3)
| Title |
|---|
| JP昭63-83260A 1988.04.13 |
| 刘湘军等."金属氧化物气敏传感器".《广州大学学报(自然科学版)》.2007,第6卷(第5期),42-46. |
| 宁文生等."气敏材料的研究进展".《材料导报》.2002,第16卷(第8期),45-47. |
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