WEAR OF METAL STIRRING RODS IN MOLTEN ALUMINUM AND SUSPENSIONS OF ALUMINA PARTICLES IN MOLTEN ALUMINUM

The wear of stainless steel and titanium stirring rods in molten alumi nium and a suspension of alumina particles in molten aluminium was stu died. The known characteristic of more rapid wear by stainless steel t han titanium was confirmed and the suspension of alumina particles was found to accelerate wear of both metals. Examination of worn specimen s revealed that the stainless steel rods were separated from the liqui d aluminium by a layer of iron, chromium and aluminium, Wear proceeded by the shedding of projections that formed on the layer into the liqu id aluminium. Alumina particles accelerated wear by abrasion of the pr ojections. The titanium was surrounded by a much thinner layer of tita nium and aluminium mixture with no projections into the molten alumini um. The distribution of wear around the blades was controlled by the f low of liquid metal and of the alumina particles around each blade.