Roundness of Casting Micro-Holes in Aluminum Alloy

Micro-holes were prepared by using metal wire coated graphite paint, and microstructure and morphology nearby micro-hole wall were observed and analysis by scanning electron microscope and energy spectrum analysis and so on. The results of showed that morphology of micro-hole wall was not nearly changed when pouring temperature range was 700 ~ 800 °C. However, carbon element was detected on the micro-hole wall when using metal wire coated graphite paint hole core to prepare micro-hole. The diffusion of carbon from surface of hole cores increased with the increasing of temperature. And then, the amount of carbon or carbides retained on the surface of the micro-holes wall also increased. They will form tiny bulges on the surface of the micro-holes after the molten metal cooling, which result in affecting the surface quality of micro-holes.