On-Line Monitoring of Sintering Process using Ultrasounds

为了实现陶瓷烧结过程的超声在线监测，研制了能在1273K高温环境下提供脉冲回波测量的高性能超声传感器和实时数据采集系统。可行性研究和几个基本的实验已经进行，并尝试在723 K的氧化铝烧结过程中进行了监测，使用开发的传感器与采集系统。（1）选用细晶粒高密度氧化铝作为高温超声传感器的缓冲棒材料，其上级导波性能优越。结果表明，所研制的由锥形缓冲棒和水冷系统组成的超声波传感器在1123K下工作良好。(2)实验室验证的使用开发的传感器和采集系统的烧结氧化铝粉末的监测已被证明使用等离子烧结机在723 K。在炭模中对氧化铝粉末进行了超声检测，结果表明，超声缓冲棒技术是一种很有前途的在线监测技术，但仍需进一步研究。

High performance ultrasonic sensors that provide pulse echo measurements in a high temperature environment up to 1273 K and a real-time data acquisition system have been developed in order to make ultrasonic on-line monitoring for ceramic sintering processes. Feasibility study and several fundamental experiments have been carried out and an attempt to monitor an alumina sintering process at 723 K has been made using the developed sensors with the acquisition system. The obtained results are the following:(1) A high density alumina with fine grains has been chosen as a buffer rod material used for high temperature ultrasonic sensors, because of its superior wave guidance ability. It has been shown that the developed ultrasonic sensor consisting of a tapered buffer rod and water cooling system works well even at 1123 K.(2) Laboratory validation of the use of the developed sensor and acquisition system for sintering monitoring of alumina powders has been demonstrated using a plasma sintering machine at 723 K. An ultrasonic signal with poor S/N ratio has been measured from alumina powders packed in a carbon die.It is therefore considered that the developed ultrasonic buffer rod technique is a promising candidate for on-line monitoring during powder sintering processes and further studies are needed for practical use.