Layered structure of AK12-Al2O3 and AK12- SiC composites formed by the centrifugal casting
Anna Dolata-Grosz, Józef Śleziona, Jakub Wieczorek, Maciej Dyzia Politechnika Śląska, Wydział Inżynierii Materiałowej, Metalurgii i Transportu, ul. Krasińskiego 8, 40-019 Katowice
Annals 2 No. 5, 2002 pages 305-308
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abstract Layered reinforcing of cast compositions, which is the subject of this article allows to recive good combination of special useful properties of reinforced areas with expected mechanical properties of regions, which do not posses ceramic particles. The formation of banded structure to the take possible different technology, as well during traditional gravity casting. Here, the gradient is controlled mainly by the difference in density between the matrix and the particle materials and by the solidification. One of the solutions that enable increasing the quantity of the reinforcement in superficial regions is centrifugal casting. This technology makes possible forming the structure of the materials any reinforcement distribution. Centrifugal force applied to a mixture of molten metal any ceramic particle compounds, leads to the formation of a desired composition gradient. Here, the particle concentration’s gradient is depended by the much-differed variables such as: rotational speed centrifugal form, particle volume fraction, and reinforcement granulation’s as well crystallization conditions. etc. In the article is presented the banded structure of the composite AK12-Al2O3 and AK12-SiC that was obtained by the centrifugal casting. In this process was applied four rotational speeds: 750, 1000, 1500 and 3000 r.p.m. Reinforcement alumina and silicon carbide particles were used at 30, 50 and 100 μm size. For aluminum matrix three particles volume fraction 5%, 10% and 15% was applied. The macrostructure’s reinforcement arrangement of composites obtaining after centrifugal casting has been shown in Figure 1. The schematic displacement rich zone of ceramic particles has been shown in Figure 2. The microstructure of the studied composite shows banded structure (Fig. 2) that obtained was by the centrifugal casting. After this process in sleeves casting another reinforcement displacement on the thickness, uniform and lamellar - internal zone (Fig. 2a) and external zone (Fig. 2b) was observed.