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Plain Bearing Failure
7.0 Thermal ratcheting of Tin-Rich White Metals and Thermal Fatigue
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7.1 Thermal Ratcheting of Tin-Rich White Metal
7.2 Thermal Fatigue of White Metal
7.3 Thermal Ratcheting and Thermal Fatigue - Summary
Tin has an anisotropic crystal structure; this results in different physical properties in different directions in the crystals. The crystal size in tin-rich white metals is large (ca. 5 mm) and in thrust pads subject to thermal cycling, the difference in the coefficient of thermal expansion can cause angular roughening corresponding to the grain size of the tin-rich crystals in the white metal.
Thermal ratcheting does not occur with lead-rich white metals.
The differential thermal coefficient of expansion between white metals and steel can result in thermal fatigue if thermal cycling takes place. This is most commonly found on thrust pads with dovetailed joints where differences in the thermal conductivities of the two metals are also a factor