Staymates Matthew, Gillen Greg
Surface and Microanalysis Science Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA.
Rev Sci Instrum. 2012 Jul;83(7):075113. doi: 10.1063/1.4737626.
In this work, we describe a thermo-microscope imaging system that can be used to visualize atmospheric pressure thermal desorption phenomena at high heating rates and frame rates. This versatile and portable instrument is useful for studying events during rapid heating of organic particles on the microscopic scale. The system consists of a zoom lens coupled to a high-speed video camera that is focused on the surface of an aluminum nitride heating element. We leverage high-speed videography with oblique incidence microscopy along with forward and back-scattered illumination to capture vivid images of thermal desorption events during rapid heating of chemical compounds. In a typical experiment, particles of the material of interest are rapidly heated beyond their boiling point while the camera captures images at several thousand frames/s. A data acquisition system, along with an embedded thermocouple and infrared pyrometer are used to measure the temperature of the heater surface. We demonstrate that, while a typical thermocouple lacks the response time to accurately measure temperature ramps that approach 150 °C/s, it is possible to calibrate the system by using a combination of infrared pyrometry, melting point standards, and a thermocouple. Several examples of high explosives undergoing rapid thermal desorption are also presented.
在这项工作中，我们描述了一种热显微镜成像系统，该系统可用于在高加热速率和帧率下可视化大气压热脱附现象。这种多功能且便携的仪器对于在微观尺度上研究有机颗粒快速加热过程中的事件很有用。该系统由一个变焦镜头和一个高速摄像机组成，高速摄像机聚焦在氮化铝加热元件的表面。我们利用高速摄像、斜入射显微镜以及前向和后向散射照明，以捕捉化合物快速加热过程中热脱附事件的清晰图像。在典型实验中，感兴趣材料的颗粒被快速加热至沸点以上，同时相机以数千帧/秒的速度拍摄图像。数据采集系统以及嵌入式热电偶和红外高温计用于测量加热器表面的温度。我们证明，虽然典型的热电偶缺乏准确测量接近150℃/秒的温度变化率的响应时间，但通过结合使用红外高温测定法、熔点标准和热电偶，可以对系统进行校准。还展示了几种高爆炸物快速热脱附的示例。
