Radiographic Observation of the Internal Porosities in Castings of High Fusible Base Alloy

In order to investigate internal porosities of high fusible base alloy castings, non-destructive inspection was carried out by radiographic method with an X-ray unit. Test samples were made of cobalt-chromium and nickel-chromium alloys, and shaped into 13 steps of wedge type castings with the minimum thickness of 0.35mm and maximum thickness of 4.55mm in an incremental increase of 0.35mm. It was found that the X-ray unit could provide clear radiographs. The internal porosities of metal denture frame, crown-bridge and dental implant made of base alloy were easy to interpret by setting the exposure time to 90 seconds with three tube voltages of 50, 60 and 70kVp according to thickness of castings.