MEASUREMENT OF VISCOSITY, DENSITY AND SURFACE-TENSION OF METAL MELTS

A modified procedure for measuring viscosity, surface tension and dens ity of metallic melts, using a gas bubble viscosimeter, is presented. The principle of measurement is based on the relation between rate of ascent of agas bubble in the melt and the melt viscosity. The rate of bubble ascent is determined by registering the moment of detachment by pressure measurement in the lance and the moment of arrival of the bu bble at the melt surface by video film and an image processing system. The procedure is tested and the limits of its application are determi ned by comparative measurements on reference metals. After tests an re ference metals, measurements are taken of the viscosity, density and s urface tension of AI-Cu alloys in the temperature range 960 - 1465 K w ith copper contents of 12.23 to 58.5%. The relationships between these Values and temperature and composition of the melt are investigated, and corresponding approximation formulae derived.