Assessment if surface properties of liquid metals and alloys in liquid media
Jacek Jackowski, Michał Szweycer, Paweł Szymański Politechnika Poznańska, Instytut Technologii Materiałów, ul. Piotrowo 3, 61-138 Poznań
Quarterly No. 2, 2006 pages 60-64
DOI:
keywords: metals, alloys, composites, surface properties
abstract Recycling of metallic casted composite materials, both suspended and with saturated reinforcement, may be often carried out effectively only in a liquid medium formulated by melting a salt mixture. Such values, like surface tension at the liquid metal - liquid medium interface or angle of wetting the solid phase (reinforcement) with the liquid matrix metal in a liquid medium can not be determined with direct measurement technique. Nevertheless, knowledge of these values is necessary for purposes of analysis of the recycling process, interpretation of the results of laboratory experiments, designing, and verification of the process conditions. The shape of a drop of metal lying in the surrounding of a liquid medium could be measured only upon its solidification and removal of the surrounding. The paper presents the results of investigation of surface tensions and wetting angles of the alloys based on measurement and analysis of changes in the shape of the liquid metal drop, caused by its solidification. The low-melting Wood’s alloy and commercial lead-antimony alloy (OT7 alloy) have been investigated. The changes in the drop behaviour have been observed in accordance with the diagram shown in Figure 1, with the help of the device presented in Figure 2. The device enabled continuous observation and recording of the profile of a liquid metal drop located at the bed made of composite reinforcement material. The study included observation and measurement of drop geometry, assessed with the help of considerably magnified drop profiles recorded with a digital camera. Temperature of the bed-drop system was stabilized with a heater provided with a thermostat assembled in the measurement device base. An example picture of a liquid metal recorded with the device and processed with the use of a computer program is shown in Figure 3. Profiles of liquid drops of the OT7 alloy and their after-solidification profiles are shown in Figure 4. Results of the measurements and calculations are specified in Tables 2 and 3. It was shown that in the systems subject to the research the effect of inevitable deformation of the metal drop undergoing during its solidification on the results of inter-phase properties of the systems is so insignificant that they might be used for purposes of analysis of the processes conducive to separation of the composite components. The differences in the values of surface tension calculated for solid and liquid metal drops do not exceed the level provided by specialist literature sources. The values may be used for purposes of analyzing of the processes of separation of the composite components undergoing in liquid environments, where the surface properties can not be directly measured.