The Preparation Of The Surface Composites With High Frequent Magnetic Field

As the development of the science and technology, new technics appears, and the EMP has become more consummate. As the application of the new technics on the preparation of surface composites, high frequent magnetic field has been regard.In this paper, electromagnetic body force has been deduced based on the Maxwell equation. And a calculational model which can calculate the migrated velocity of the solid grain in the molten metal has been set up. Further more, the influencing factor on the migrated velocity has been analyzed, include the grain diameter, sample diameter, shape coefficient of the grain and so on. Based on the migrated velocity of the solid grain, the migrated time of the solid grain in the molten metal can be deduced.Electromagnetic force is imposed on the metallic conductor when the melt is exposed to an electromagnetic field, also, the metallic conductor would be heat up by induced heat, hi this paper, induced heat of the metal has been calculated, and the dissipated heat of the metal also been calculated in natural convection;the induced heat and dissipated heat makes the molten metal keep the temperature steady, which will satisfy the required temperature on the preparation of the surface composite material.Through analyzed the migrated velocity of the solid grain in the molten metal, experiments has been studied next. Different kind of Al-Si alloy with different Si content, and different dimension of the sample has been studied. The result of the experiments show that:1. To the 10 mm diameter sample, when input power is 2-3kw, high frequent magnetic field has been exposed, and keep the molten metal at around 650 V, with 20s, efficient assembled of the Si grain can be achieved, so the surface composites with better surface quality can be produced. As the increasing of the sample diameter, the exposing time of the magnetic field will become longer. To the 16mm diameter sample, it cost 60s, and when the diameter increased to 22mm, it cost 80s.2. To the 10mm diameter sample, when input power is 2-3kw, assembled effect of theSi grain in different molten temperature has been analyzed. To the Al-16wt%Si alloy, the best temperature range to exposed the magnetic field is at 580-600 V, and to the Al-24wt%Si alloy, the best temperature range to exposed the magnetic field is at 600-620 V. As the increasing of the Si content, the temperature range will increased also. But generally, the temperature rang will keep at the nether of the solid-liquid phase.