High Resolution Measurements by Focused Ultrasonic Waves in Molten Metal

这是第一份演示高分辨率测量的报告。通过在高温下聚焦在金属熔体中的超声波。研制了聚焦超声传感器，并在10 MHz的脉冲回波模式下进行了实验，以考察所研制的传感器的性能。在本实验中使用熔融的锌、铝和镁。获得的主要结果如下：(1)利用聚焦超声传感器，即使在锌熔体中，超声波也能聚焦到一个波长左右的小光点上，获得高的横向分辨率(650℃)。(2)用普通的C扫描技术对锌熔体进行高分辨率超声成像，根据反射信号的幅度和时延变化得到超声图像。(3)还尝试了对锌熔体中悬浮颗粒的检测。在透镜的焦区，颗粒的背向散射信号清晰可见。(4)进行了V(Z)曲线的测量，并成功地测定了浸入锌液中的碳化硅陶瓷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.