Patent ID: 8070364
Filing Date: 2011-12-06
Classification: F16C,Y10T

Abstract:
1. A roller bearing comprising: at least one first rolling part of a ceramic material having a first contact surface; at least one second cooperating rolling part comprising steel with a martensitic microstructure and having a second contact surface, at least a portion of the second contact surface configured and positioned to make rolling contact with the first surface; and the microstructure having residual compressive stresses beneath at least a portion of the second contact surface at least in a load-free state, wherein a level of the residual compressive stresses of an entire region starting from the second surface down to a depth of 40 μm corresponds at least to an absolute value of 300 MPa, wherein the residual stresses decrease in magnitude below the depth of 40 μm, and wherein the second rolling part includes a thermochemically produced outer layer to include the second contact surface, and the second contact surface is fully machined, wherein the thermochemically produced outer layer is nitrogen-enriched, wherein the outer layer of the second rolling part, at least at the second surface, has a hardness of at least 850 HV0.3 at a depth of 0.05 mm below the second surface, wherein the outer layer has been heat-treated twice, and the second heat treatment is at a process temperature of at least 400° C.