| 초록 |
Present years, Near net-shape metallic foams are produced and researched by Presursor technique for a productivity. this is because of instability of melt at foaming stage during decomposition of TiH2. In this article, however, evaluate the fabrication characteristic of near net-shape metallic foams by direct foaming method. Pay due regard to cost, Al-Si alloys and Plaster was used for base material and mould material. Ca and TiH2 added to molten Al as thickening and blowing agent for make sure to stable condition of bubbles. Thickening time was about 10 minute with stirring speed of 600 rpm. Foaming time was 30~120 seconds for evaluate the optimum foaming condition. Amount of additional Si was affected to porosity and cell size distribution of casting. The shape of casting was simple-shape of dish and relatively complex shape of gear by plaster mould with fixed size. Porosity of near net-shape goods was measured by Archimedes method. It is found that porosity was increased with decreasing pouring time and increasing blowing agent. On the other hand, it seems that increasing poring time and thickening agent make the poor porosity. |
