【作者】 王锐；

【导师】 伍萍辉；

【作者基本信息】 河北工业大学 ， 电子与通信工程（专业学位）， 2022， 硕士

【摘要】 液态氢是运载火箭发动机使用的主要燃料之一。液氢的泄露会造成低温冻伤,也会影响到航天器的结构强度,甚至发生爆炸危及航天员生命安全。此时氢气传感器需工作在真空环境,因此对现有的氢气传感器技术提出了更高的要求。具有工艺简单、成本低廉和易于集成等优点的电化学型氢气传感器出现在了大家眼前,适合应用在低温、无氧的工作环境中,为推进剂泄漏检测提供成熟的解决方案。其中离子液体由于具有低挥发性、不燃烧和高离子导电性等优点在氢气传感器电解质领域具有很大的前景。本论文利用酸碱中和法合成了两种质子型离子液体,再通过热致相分离法制备基于离子液体的固体聚合物电解质,最后通过丝网印刷技术制备平面电极,目的是开发在低温无氧的工况条件下应用于氢燃料泄漏检测系统中的电化学氢气传感器。通过XRD、SEM、XPS、TGA和DSC等多种表征手段对平面电极和固体聚合物电解质进行了表征分析。探究工作电位、气体流速、温湿度和器件结构对氢气传感器灵敏度的影响,并且通过动态气敏测试系统,对氢气传感器的恢复性和稳定性进行了测试分析;同时,借助循环伏安法,计时电流法等电化学分析方法探究了传感器对氢气的响应机制。基于上述制备工艺与表征测试方法,本文通过将离子液体加入PVDF制备固体聚合物电解质,并放置在以多孔陶瓷为衬底的平面电极上,开发了一种固态氢气传感器。该设计使氢气快速扩散到三相界面,提高传感器的灵敏度,改善器件对氢气的响应性能。结果表明,制备的多孔陶瓷由纳米颗粒堆叠形成多孔结构,孔隙率高,且气孔分布均匀;平面电极表面存在金属相Pt和Pt氧化物,这表明制备的平面电极是具有高透气性的氢敏电极。掺杂PVDF没有改变离子液体的热稳定性和导电性;光谱也证实了PILs/PVDF膜的一致性。气敏动态测试结果表明:氢气传感器在无氧环境下显示出良好的重复性和恢复性;相比于传统结构,使用固体聚合物电解质结合多孔陶瓷作为电极衬底的氢气传感器的灵敏度较高,证明了该器件结构的普适性;基于质子型离子液体与非质子型离子液体的氢气传感器均展现出的高灵敏度,其中离子液体的粘度、质子电导率等都是影响传感器响应性能的重要因素。本文的工作为应用于氢燃料泄漏检测的氢气传感器提供了一个新的思路和理论支撑。更多还原

【Abstract】 Liquid hydrogen is one of the primary fuel used in rocket engines.The leakage of liquid hydrogen can cause frostbite to human body,but also affect the structural strength of the spacecraft,and even an explosion endangering the lives of astronauts.The hydrogen sensors need to operate in a vacuum environment,thus placing new demands on existing sensor technology.With the advantages of simple process,low cost and easy integration,electrochemical hydrogen sensors are suitable for application in low-oxygen and lowtemperature environment,and can provide mature solutions for propellant leak detection.Ionic liquids have great promise in the field of electrolytes for hydrogen sensors because of their non-volatility,non-combustibility and high ionic conductivity.In this study,two protic ionic liquids were prepared using an acid–base reaction,solid polymer electrolyte was fabricated by a thermally induced phase separation,and the planar electrode was made based on screen printing technology.The aim is to develop electrochemical hydrogen sensors that can be applied in propellant leakage detection systems under anaerobic conditions.The XRD,SEM,XPS,TGA,and DSC methods were used to analyzed planar electrodes and solid polymer electrolytes.The effects of working potential,gas flow rate,temperature and humidity,and device structure on the sensitivity of the hydrogen sensor were investigated,and the recovery and stability of the sensor were tested and analyzed by a dynamic gas-sensitive test system;at the same time,the response mechanism of the sensor to hydrogen was investigated by electrochemical analysis methods such as cyclic voltammetry and constant potential chronoamperometry.Based on the above preparation process and characterization test method,a solid-state hydrogen sensor was developed in this paper by adding ionic liquid to PVDF to prepare a solid polymer electrolyte and placing it on a planar electrode with porous ceramic as the substrate.This design allows the gas to diffuse quickly to the three-phase(gas/electrode/electrolyte)interface,improve the response performance of the sensor to hydrogen gas and increase the sensitivity of the sensor.The characterization results show that the porous ceramic is formed by nanoparticles stacked out to form a porous structure with high porosity and uniform pore distribution;presence of metallic phases Pt and Pt oxide on the surface of planar electrodes,which indicates that we prepare the planar electrode is a hydrogen-sensitive electrode with high permeability.The doping of PVDF did not change the thermal stability and electrical conductivity of the ionic liquids;the spectra also confirmed the consistency of the protic ionic liquids/PVDF films.The gas-sensitive dynamic test results show that the sensor shows good repeatability,recovery and stability under anaerobic conditions.Results of gas-sensitive dynamic tests show that the hydrogen sensors shows good repeatability and recovery under anaerobic conditions;the higher sensitivity of the hydrogen sensor using a solid polymer electrolyte combined with porous ceramics as the electrode substrate compared to the conventional structure,demonstrating the universality of the device structure;The high sensitivity exhibited by hydrogen sensors based on protic ionic liquid and aprotic ionic liquid,the viscosity and protonic conductivity of the ionic liquid are important factors affecting the response performance of the sensors.The work in this paper provides a new idea and theoretical support for hydrogen sensors applied to propellant leak detection.更多还原