A New Type Of Enthalpy Coating And Its Application In Thin-Wall Casting Process

With the developing of solidification theories and technologies, thin-wall sand mould casting will be substituted by die-casting for increasing the cooling rate. However, die-casting has dash cold effect especially for the thin-wall casting, which will bring cold shuts, running insufficiency etc. and make the quality of casting declining. Therefore, improving the filling capacity becomes a core problem for the application of die-casting in thin-wall casting.This paper explains the reasons for the deficiencies of tilling capacity in thin-wall die-casting. Two ways are turned out for improving the tilling capacity i.e. heat-insulating coating and heat-releasing coating. The commercial A3 57 alloy was used as the examples for the experiment to test the performance of the coating.To commingle some appropriate reducing agents into the heat-insulating coating releases heat through radiative reaction when heat by melting metal during filling process. It can improve the filling capacity- Two kinds of zinc oxide coating with additions of Mg or Fe2O3 powders respective were tested. It is found that the latter one is better.The influence of the coatings on the cooling rate and microstructure of the casting were also studied. The result show that coating with Fe2O3 powder is much more suitable. The T6 heat treatment technics of A357 alloy casting has been also discussed in this paper. The evolvement behaviors of Si, Mg2Si etc. components during heat treatment have been investigated. The optimized T6 heat treatment parameters was also obtained.