Erosion Damages of Sintered Metals

Abstract

In the present paper, erosion tests are carried out by vibrating a disc at the free end of a magnetostrictive oscillator close to the surface of sintered metals in water or in oil. The damages are due to fatigue by the collapse pressure of cavitation bubbles under a thick liquid film and due to fatigue by the surface shearing of a squeezed film under a thin liquid film. The thickness of liquid film showing the maximum value of the weight loss which is due to cavitation erosion, is larger on the sintered metal of higher porosity, because the porous surface of the sintered metal is easily filled with cavitation bubbles. The resistance to the erosion damages of sintered iron is lower than that of mild steel, and increases with smaller porosity, being proportional to the square of Brinell hardness. The resistance to the erosion damage of sintered copper-lead alloy of low porosity is considerably higher than that of lining copper-lead alloy. The fall-off particles of the former are very small compared with those of the latter. The resistance of high porosity alloy is also higher than that of the lining alloy when the film thickness is small.