Temperature independent resistive oxygen sensor for the control of combustion processes

需要氧传感器来控制化石和可再生资源的燃烧过程，以确保它们的排放符合严格的限制。需要能够承受非常恶劣的废气条件的长期稳定的传感器。为了控制燃烧过程和废气后处理系统以最大限度地减少污染物排放，组合式气体传感器(也称为多气体传感器，例如SCR废气后处理系统中的CO/O2或NH3/O2)将受到业界的关注。在陶瓷平面工艺中，通过在传感器衬底上涂覆多层功能薄膜，可以实现多层气体传感器的小型化，其电阻或阻抗随被测气体的变化而被测量。虽然这里应用的转移项目只涉及前一个项目在温度无关的阻性氧传感器上取得的成果的实施，但长期目标是将多个传感器集成到单个平面传感器组件中，形成多个气体传感器。通过将氧传感器与氧交叉敏感气体传感器相结合，可以消除额外的交叉敏感，从而提高对不同气体的检测的准确性。这位工业项目合作伙伴在平面技术中研究基于阻抗的氮氧化物传感器已经有一段时间了，他也在朝着这个方向努力。在前面的DFG资助的项目中，BFATx=BaFe[(1-x)-0.01]Al0.01TaxO(3-y)被作为一种功能材料进行了研究，该材料的电阻率与氧含量高度相关，但在700-800°C之间与温度无关。在项目接近尾声时，还为使用新型粉末气溶胶沉积方法(PADM)制造的BFATx薄膜提供了原理上的功能性证明，以用于温度无关的电阻氧检测。在这项移交工程中，一方面要建设完整的传感器设备作为示范，另一方面要为实施回答长期稳定和抗中毒的重要问题。对于使用经典厚膜技术制造的BFATx功能膜因此是多孔的传感器，以及使用新型PADM沉积BFATx膜的传感器来说，这是比较合适的。基于前期研究开发的BFATx功能膜的氧传感器是否适用于燃烧和废气后处理过程的控制，这是一个需要回答的问题。然而，与此同时，这些问题也涉及气敏层的长期稳定性和中毒等有趣的问题，这些问题的发现可能会影响对气体传感器的总体理解。

Oxygen sensors are required to control combustion processes of both fossil and renewable resources in order to ensure that their emissions comply with the strict limits. Long-term stable sensors that can withstand the very harsh exhaust gas conditions are required. In order to control combustion processes and exhaust aftertreatment systems to minimize pollutant emissions, combined gas sensors (also called multi-gas sensors, e.g. CO/O2, or NH3/O2 in SCR exhaust gas aftertreatment systems) would be of industrial interest. Multi-gas sensors can be realized in ceramic planar technology as miniaturized gas sensors by applying several functional films to the sensor substrate, whose resistance or impedance is measured as a function of the gases to be detected. Although the transfer project that is applied here will only deal with the implementation of the results achieved in the previous project on the temperature-independent resistive oxygen sensor, the long-term goal is to integrate several sensors into a single planar sensor component to form a multi-gas sensor. By combining the oxygen sensor with an oxygen cross-sensitive gas sensor, additional cross-sensitivities could be eliminated, thus increasing the accuracy of the detection of different gases. The industrial project partner, who has been working on an impedance-based nitrogen oxide sensor in planar technology for some time now, is also working in this direction. In the preceding DFG-funded project, BFATx = BaFe[(1-x)-0.01]Al0.01TaxO(3-y) was investigated as a functional material with a high dependence of the resistivity on the oxygen content but being temperature-independent between 700 and 800 °C. This behavior was also described in terms of defect chemistry. Towards the end of the project, a functional proof of principle was also provided for BFATx films for temperature-independent resistive oxygen detection manufactured using the novel powder aerosol deposition method (PADM). In this transfer project, on the one hand, complete sensor devices are to be built as demonstrators, and on the other hand, important questions of long-term stability and poisoning resistance are to be answered for the implementation. This is to be done comparatively for sensors whose BFATx functional films are manufactured using classical thick-film technology and are therefore porous, and for those sensors whose BFATx films are deposited using the novel PADM. The question should be answered whether oxygen sensor based on a BFATx functional films developed in the previous project are suitable for controlling combustion and exhaust gas aftertreatment processes. At the same time, however, these questions also address fundamentally interesting issues of long-term stability and poisoning of gas-sensitive layers, the findings of which may have an impact on the understanding of gas sensors in general.