Development of high temperature ultrasonic 2-D array sensor and its application to solidification monitoring for molten metals

点击翻译按钮获取中文摘要

Development of a high temperature ultrasonic 2-D array sensor and its application to solidification monitoring of molten metals have been studied. The main results obtained are the following:(1) Conventional ultrasonic 2-D array sensors have been examined to verify the capability and feasibility of ultrasonic imaging in a water environment at room temperature. The results have showed that the use of the conventional technique using a 2-D ultrasonic array transducer (8×8, 16× 16)coupled with a bulk buffer medium cannot be used for molten metal monitoring because of its poor spatial resolution and time consuming for imaging. It is therefore suggested that a high performance ultrasonic buffer rod and relating techniques should be used for fabricating a high temperature ultrasonic array sensor.(2) A high temperature ultrasonic sensor with a tapered clad buffer rod is designed using a numerical simulation technique (FDM) and its ability for a solidification process monitoring of a molten aluminum alloy has been demonstrated. The temperature distribution around the probing end of the buffer rod sensor in the molten aluminum has also been evaluated by a numerical calculation (FEM). It is found that the ultrasonic buffer rod sensor is a powerful element that can be used for fabricating the ultrasonic array sensor.(3) A long buffer rod sensor of 1 m length has been designed and fabricated, and then the laboratory validation of the use of such long sensor for molten metal monitoring has been examined. In addition, surface roughness evaluation methods based on reflection and scattering phenomena have been developed to evaluate surface topography quantitatively. It is expected that such roughness evaluation methods could be useful for monitoring and evaluating the surface morphology of a solidification interface of molten metals. It is therefore considered that the developed long buffer rod sensor is a promising candidate for constructing an effective array sensor.