Control of Liquid-Drop Surface Shape in Melt

The carbon steel samples of great quality can not be melted using a high-temperature confocal scanning laser microscopy(HTCSLM). On account of only arc surface of the tiny liquid-drop top is observed, it is difficult to obtain distinct images. The shape variation of the tiny liquid-drop is studied experimentally in this article. The results show that the shape of the liquid-drop will be changed at 1600°C, when the carbon steel sample of 0.5g is laid on the Al2O3sloping of 15 degrees. Though the radius of curvature of the liquid-drop top surface is obviously enlarged, the impact of improving the surface shape of liquid-drop through the gravity flow of tiny liquid-drop is finite. For the carbon steel sample of less than 0.8g, the hanging drop is automatically formed in the melting process under the condition that the gap between the solid sample and Al2O3single crystal plate is 0.3mm, and the shape retains invariant when it is hold for 20 min at 1600°C. The contact surface between the sample and Al2O3single crystal plate is 24mm2.

Depth Measurement of Surface-Breaking Cracks Using Point-Source/Point-Receiver Acoustic Transducer

ABSTRACTA newly developed point-source/point-receiver (PS/PR) acoustic transducer is used for measuring the depth of surface-breaking cracks. The transducer consists of two miniature conical PZT elements which form a transmitter/receiver pair for generating and detecting surface waves. A tone-burst measurement system operates the PS/PR transducer at a fixed frequency. When a surface-breaking crack is present in between the transmitter and receiver, the change in time-of-flight of surface wave propagation caused by the crack is measured and used to estimate the crack depth. To verify the feasibility of this method, machined slots on a carbon steel sample are tested by the PS/PR transducer for crack depth determination. Good experimental results are obtained. Future applications and improvements on the PS/PR transducer system are addressed.