Study on Sintered Gas Sensors of Acetylene and Formaldehyde

　　Study on Sintered Gas Sensors of Acetylene and Formaldehyde
　　Technological progress brings us high life quality, on the contrast, italso brings us many problems, such as, bad gas leaks from the process ofmanufacture and environmental pollution, etc. All these potential dangerswill threaten human’s health and safety. Thinking about that, we carriedthrough a research about the acetylene gas sensor and formaldehyde gassensor, the front can give an alarm to the transformation instrument, the lattercan give a simple and rapid test Ring neodymium magnet to the room’s air quality.In the process of research, we utilize the method of chemicaldeposition to prepare the Sn(OH)4 crystal, then turn it into SnO2 by sintering.These basal materials are our experimental need. Gas sensor’s facture is verycomplex: first, we need get apropos materials including SnO2、SnCl4、SnO、Sn(OH)4、acid asbestos and noble metal, then we put all of these into an agatemortar to skive.
　　After two hours, we get a kind of plasm, we daub the plasmon the surface of the sensors right now, and then heat until they turn dry. Atlast, we put it into the furnace to sinter, keeping the temperature at about650℃, and when temperature of the furnace turns to the room temperature,we take them out, joint the heating resistance (about 25-30?), waiting test. For the part of research of the acetylene gas sensor, we selected ZrO2、La2O3、Sm2O3、Pr6O11 and La2(SO4)3 as doping, through all the facture steps(described above), we start to test their sensitivity, selectivity, stability,response and recovery characteristics. From test results, we know doping 6%Sm2O3 is the best one, its IH is 130mA, selectivity is also good (better thanH2 and CO), and it can test well the lower concentration of acetylene,response and recovery characteristics are good , about 20 seconds to 30seconds (graph 3.1-3.6).For this part of research of the formaldehyde gas sensor, first,according to the literature, we know it is possible to enhance the sensorsensitivity and selectivity by doping http://www.chinamagnets.biz some noble metal into Sn(OH)4,through research, we got a conclusion: the gas characteristics of Sn(OH)4doping some noble metal is better than SnO2 doping some noble metal, thebest sintering temperature is 650℃, keeping an hour. And then we selectedAgNO3、H2PtCl6、PdCl2、HAuCl4 and RhCl3 as doping, through all the facturesteps (described above), we start to test their sensitivity, selectivity, stability,response and recovery characteristics. From test results, we know dopingRhCl30.2% is the best one, its IH is 90mA, selectivity is good (better thanchloroform、ethanol and toluene), and it can test well the lower concentrationof formaldehyde: 5ppm, and sensitivity can reach above 3, response andrecovery characteristics are also good, about 50seconds to 60 seconds (graph4.1-4.17).We can’t do more deep job as the limited of time and experimentalcondition. The experiment should be improved in the future time. And the gascharacteristics may continue to improve in the future. In a word, we basicallysucceed in making the acetylene gas sensor and formaldehyde gas sensor. Wehope our research can pave the road for the deep research.