| 摘要 |
PURPOSE:To decrease the variance in the amt. of the platinum to be deposited and to form a temp. compensating element having specified oxidation activity and selectivity with good reproducibility by preliminarily depositing a slight amt. of a platinum catalyst on active alumina powder then sticking the same to a coil and calcining the powder. CONSTITUTION:The same active alumina powder as the active alumina powder used for a gas detecting element is immersed into an aq. chloroplatinic acid soln. and after stirring, the moisture is evaporated by dry the soln. while the soln. is stirred on a heated bath. The active alumina powder is thereafter taken out and is thoroughly agitated in an alumina mortar. The powder is reduced in hydrogen after drying. An alumina sol is mixed with the active alumina powder deposited with a slight amt. of the platinum and further a suitable amt. of pure water is added there to to form the paste. A spherical element is formed by using such paste and is calcined after drying to obtain the spherical temp. compensating element deposited with a slight amt. of the platinum. A pair constituted of such temp. compensating element and gas detecting element is used as the sensor.
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