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采用丝网印刷法将钨酸分解得到的氧化钨粉末制备成氧化钨厚膜气敏传感器,并先后在氢气和空气气氛中进行还原和氧化处理,系统研究了氢气浓度和氧化时的升温速率对敏感膜的形貌、结构和CO气敏性能的影响。结果表明,经氢气还原-空气氧化后,敏感膜表面形貌由近似球形的颗粒转化为表面光滑两端开口的集束棒状或规则的四方柱状,而晶体结构则没有发生改变。敏感膜对CO的灵敏度(Rair/RCO)随CO浓度的增加和测试温度的升高而增大。与没有进行气氛改性的敏感膜相比,经10%H2气氛还原并在600℃空气中以5℃/min氧化处理后的敏感膜对CO具有最大的灵敏度,其对3.8×10-5CO的灵敏度提高了13.3倍。即通过对敏感膜进行气氛改性可显著提高对CO的敏感性能。
The tungsten oxide powder obtained by the decomposition of tungstic acid was prepared into a tungsten oxide thick film gas sensor by the screen printing method and then reduced and oxidized in a hydrogen atmosphere and then in an air atmosphere to systematically study hydrogen concentration and the rate of temperature rise during oxidation Sensitive film morphology, structure and CO gas sensitivity. The results showed that the surface morphology of the sensitive membrane changed from spherical particles to bundles of rods or regular tetragonal columns with smooth surfaces at both ends after hydrogen reduction and air oxidation. However, the crystal structure did not change. Sensitivity of the sensitive membrane to CO (Rair / RCO) increases with increasing CO concentration and increasing test temperature. The sensitivity of the sensitive membrane reduced by 10% H 2 atmosphere and oxidized at 600 ° C in air at 5 ° C / min showed the greatest sensitivity to CO as compared with that of the sensitive membrane without atmosphere modification. The sensitivity to 3.8 × 10 -5 CO Sensitivity increased by 13.3 times. That is, the sensitive properties of CO can be significantly improved by modifying the atmosphere of the sensitive membrane.