High Resolution Measurements by Focused Ultrasonic Waves in Molten Metal

这是第一份展示高分辨率测量的报告。在熔融金属高温下聚焦超声波。研制了聚焦超声传感器，并在10 MHz脉冲回波模式下进行了实验研究。本实验采用熔融锌、铝和镁。主要研究结果如下：(1)利用聚焦式超声波传感器，即使在650℃的熔融锌中，超声波也能聚焦在一个波长左右的小点上，具有较高的横向分辨率。(2)采用常见的c扫描技术对熔融锌进行高分辨率超声成像，根据反射信号的振幅和延时变化获得超声图像。人们还尝试检测悬浮在熔融锌中的颗粒。来自粒子的反向散射信号在透镜的焦点区域清晰可见。(4)通过V(z)曲线测量，成功测定了浸入锌液中的陶瓷（SiC）板的泄漏表面声波速度。

This is the first report to demonstrate high-resolution measurements. by focused ultrasonic waves in molten metal at high temperature. Focussing ultrasonic sensors were developed and some experiments were carried out at 10 MHz in a pulse echo mode to investigate the performance of the developed sensors. Molten zinc, aluminum, and magnesium were used in the present experiments. The main results obtained here are the following :(1) Using the focussing ultrasonic sensors, the ultrasonic wave can be focused onto a small spot of about one wavelength to provide high lateral resolution even in molten zinc at 650 ℃.(2) High-resolution ultrasonic imaging is carried out in molten zinc by the common C-scan technique and ultrasonic images are obtained from the amplitude and time delay variations of the reflected signals.(3) An attempt has been also made to detect particles suspended in molten zinc. Back-scattered signals from particles are clearly visible at the focal region of the lens.(4) V(z) curve measurements are performed and the leaky surface acoustic wave velocity of a ceramic (SiC) plate immersed in molten zinc is successfully determined.