Egorov S V, Eremeev A G, Kholoptsev V V, Plotnikov I V, Rybakov K I, Sorokin A A
Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod 603950, Russia.
Rev Sci Instrum. 2022 Jun 1;93(6):064708. doi: 10.1063/5.0093341.
Rapid microwave sintering of different oxide ceramics with heating rates up to 300 °C/min and zero hold time has been implemented using a 24 GHz gyrotron-based system for high-temperature processing of materials. The design of the system, principle of operation, and process control are described. Particular attention is given to the design of thermal insulation assemblies and the implementation of temperature measurement in an environment with intense electromagnetic fields. A description of an optical system for dilatometry and temperature measurement is presented. The interrelation between the automatically regulated output power of the gyrotron and the microwave power absorbed volumetrically in the sample is analyzed on the basis of energy balance considerations. The analysis is illustrated by considering examples of rapid sintering processes with ZnO-based and BaTiO ceramic samples making use of direct and susceptor-assisted microwave heating. It is demonstrated that an increase in the volumetrically absorbed power leads to the development of a controlled thermal instability, which results in a lower temperature of the densification onset.
利用基于24吉赫兹回旋管的材料高温处理系统，实现了对不同氧化物陶瓷的快速微波烧结，加热速率高达300℃/分钟且保持时间为零。描述了该系统的设计、运行原理和过程控制。特别关注了热绝缘组件的设计以及在强电磁场环境中进行温度测量的实现方式。介绍了一种用于膨胀测量和温度测量的光学系统。基于能量平衡考虑，分析了回旋管自动调节输出功率与样品中体积吸收的微波功率之间的相互关系。通过考虑以氧化锌基和钛酸钡陶瓷样品为例的直接和感应辅助微波加热快速烧结过程的实例来说明该分析。结果表明，体积吸收功率的增加会导致可控热不稳定性的发展，这会导致致密化开始温度降低。
