Resistance to wear and cavitation erosion of bearing alloys

Sliding wear and vibratory cavitation erosion tests in paraffin oil were carried out on bearing alloys, i.e. tin-based and lead-based white metals, Cu-Pb alloy and leaded bronze. In lubricated wear under mild conditions the surface is worn smooth and a slight difference exists between the wear resistances of the four alloys. In cavitation erosion an eroded surface which is much rougher than the worn surface is formed. Cavitation erosion is affected strongly by the composition and crystal structure of the alloy and thus the erosion resistances of the four alloys differ greatly, the ranking of resistance being lead-based white metal < Cu-Pb alloy < tin-based white metal < leaded bronze. The surface damage, which is caused by the joint action of cavitation erosion and wear, was also investigated by rubbing the eroded surfaces which had been exposed to cavitation erosion for various times. This damage becomes larger with increasing cavitation damage. The resistance to this damage differs much more in the four alloys tested and tends to correlate with the results of the erosion tests rather than those of the wear tests. Therefore, it is clear that the cavitation erosion resistance should be considered in the selection of bearing materials.