Assembly Technologies for Piezoelectric Sensors Operating up to 1000 °C

压电单晶可以用作谐振器来测量温度，压力或温度高达至少1000°C的气体成分。合适的传感器系统必须具有足够的功能和可靠性。这反过来又需要稳定的组装和互连技术以及兼容的传感器元件陶瓷外壳。到目前为止，还没有可用于高达1000°C温度的互连技术。出于这个原因，建议的建议包括在材料科学和系统概念方面为这种传感器产生适当的基础知识。在项目框架中，一个具有基本功能的谐振传感器元件将集成到一个功能齐全的外壳中，作为一个模型系统运行。这允许研究材料，设计和制造工艺对功能和高达1000°C的长期稳定性的基本影响。首先，有必要根据电学和热机械模型来描述传感器的功能，以了解信号传输和热机械应力的产生等现象。作为基础技术，具有适当金属化层的堆叠陶瓷将被评估为外壳组件。此外，将开发玻璃陶瓷钎焊和合适的连接技术，以组装传感器和外壳。内置传感器可以对连接的组件进行彻底的调查。通过分析不同材料之间的相互扩散过程，可以评估它们的稳定性。此外，有必要评估密封性和降解机制。模型传感器选用CTGS （Ca3TaGa3Si2O14）谐振器作为本体振荡器。它们经过验证的高达1000°C的操作稳定性允许通过利用频率的温度依赖性作为传感器信号来研究封装对传感器信号的影响。科学挑战之一是开发适当的等效电路，并伴随其表征和验证。该项目包括整个传感器系统概念设计的通用工作包，以及谐振器元件的制备和表征。包括功能性金属化在内的陶瓷外壳的开发将在弗莱堡大学完成。提供温度稳定的微晶玻璃钎焊、金属化和互连技术。温度范围高达1000°C的传感器的制备和表征将在TU Clausthal进行。基于这些测试，弗莱堡大学将根据失效物理概念建立功能行为模型和退化模型。此外，在TU克劳索尔研究了材料的传感器行为和界面，以获得有关热机械稳定性的信息。

Piezoelectric single crystals can be used as resonators to measure temperature, pressure or gas compositions at temperatures up to at lest 1000°C. Suitable sensor systems have to show an adequate functionality and reliability. This in turn requires stable assembly and interconnection technologies and compatible ceramic housings for the sensor elements. Up to now there are no interconnection technologies available for temperatures up to 1000 °C. For this reason the suggested proposal encompasses the generation of appropriate fundamental knowledge in terms of material science and system concepts for such sensors. In the frame of the project, a resonant sensor element with basic functionality will be integrated into a fully functional housing to operate as a model system. This allows investigations on fundamental effects of materials, design and manufacturing processes on the function and the long-term stability up to 1000°C. Initially it is necessary to describe the sensor functions in terms of electrical and thermo-mechanical models to gain understanding of phenomena such as signal transmission and the generation of thermo-mechanical stresses. As basic technologies, stacked ceramics with appropriate metallization layers will be evaluated as housing components. Furthermore glass-ceramic brazes and suitable joining technologies will be developed in order to assemble the sensor and the housing. The housed sensor enables a thorough investigation of the joined components. The analysis of inter-diffusion processes between the different materials allows the evaluation of their stability. Additionally it is necessary to evaluate hermeticity and degradation mechanisms. Resonators made of CTGS (Ca3TaGa3Si2O14), which operate as bulk oscillators, are chosen as model sensors. Their proven operating stability up 1000°C allows an investigation of packaging effects on the sensor signal by utilizing the temperature dependency of the frequency as sensor signal. One of the scientific challenges is the development of an appropriate equivalent circuit accompanied by its characterization and validation.The project includes common work packages for the conceptual design of the whole sensor system as well as the preparation and characterization of the resonator elements. The development of ceramic housings including a functional metallization will be done at the University of Freiburg. Technologies for temperature stable glass-ceramics brazing, metallization and interconnection will be provided. The preparation and characterization of the sensors in the temperature range up to 1000 °C will be performed at the TU Clausthal. Based on these tests, the University of Freiburg will contribute to the modelling of functional behaviour and degradation models based on physics-of-failure concepts. In addition, the sensor behaviour and interfaces of the materials are investigated at TU Clausthal to obtain information on thermomechanical stability.