Preparation and gas sensitive effect of CuO-SnO_2 nanocrystalline powders
CuO doped SnO2 nanocrystalline powders were prepared by the Sol-Gel method,which were used to manufacture gas sensors with good gas-sensing characterization.Treated at different temperature,the characteristics of the powders which had different concentrations were investigated by DSC-TG,XRD,TEM,and gas sensitive effect on gas had been measured.The result shows that the prepared nano-sized powders had large specific surface area,high surface activation and 600 ℃ was the rational annealing temperature,SnO2 gas sensors doped 4% CuO had high sensitivity and selectivity for detecting CO2.
Basing on coal and the oxygen evolving complex theory, the method of study on the spontaneous combustion by analysis the microporous in coal has been established in this article. By the electron microscope, the process of microporous volume changeing with the temperature gradually increased is observed. It is believe that the process of spontaneous combustion reaction should be carried out in the microporous. Finally, under the help with finite element analysis , the temperature field surrounding microporous has been analyzed and the distribution regularity of the temperature field has been obtain. It make the conclusion that coal surface microporous can be used as evidence of coal spontaneous combustion reaction.