具有表面微结构的自悬浮多层复合薄膜材料热传导特性研究

Thermal scene generation components based on multi-layer micro/nano films has been widely used in the sytems for “hardware-in-the-loop” (HWIL) simulation experiments to test the infrared image devices. The spatial resolution, frame rate and temperature range of the infrared scene generator are highly related to the films ' thermal properties. Therefore, the thermal properties are very crucial for the component design and performance optimization. In our project, a microscale heat transfer theory and a non-contact measurment technique based on thermography are used to investigate the thermal properties of the composite thin films. By solving the Boltzmann transport equation of the phonon the relationships between thermal conductivity and film thickness, working temperatures are studied. A thermal conductivity model considering the in plane microstructure of the thin films is proposed. By means of SEM, the effects of the film preparation parameters on its thermal properties are investigated. At the same time, a non-contact measurement method based on infrared thermography is provided to measure the thermal conductivity of the self-suspended thin films in the temperature range from 300K to 500K, in order to verify and improve our theoretical models. The models and the measurement method studied by our project will promote the development of the functional devices based on thin films.

基于热传导理论的微纳米薄膜型器件已广泛应用于红外动态场景生成系统。所产生的红外场景的性能，如空间分辨率、帧频、温度等均与材料的热传导性能密切相关。因此薄膜热导率是此类薄膜型器件设计的重要参数。本项目拟从微观传热理论和实验测量方法两个方面对微纳米尺度薄膜的热传导特性进行研究。通过求解声子的Boltzmann输运方程研究薄膜材料热导率与薄膜厚度及工作温度的关系。通过建立微结构传热模型，分析薄膜面内微米尺度结构对热导率的影响。此外，结合扫描电镜等微观表征手段研究薄膜的制备工艺对薄膜微结构及传热特性的影响。在实验测量上，提出了一种利用红外热像的非接触式自悬浮薄膜热导率测量方法，以实现300-500K温区的多层复合薄膜热导率测量。从而验证理论计算的正确性，实现对理论模型的改进和优化。进而为微纳米薄膜型器件的特性优化提供理论依据和技术手段。