Ion implantation of silicon nitride ball bearings

[摘要] A program has existed for determination of the effect of ion implantation on the rolling contact performance of silicon nitride ball bearings. The hypothesis was that stress concentrations reflected into the bulk due to topography such as polishing imperfections, texture in the race, or transferred material, might be reduced due to surface amorphization. Forty-two control samples were tested to an intended runout period of 60 h. Six ion implanted balls were tested to an extended period of 150 h. The bearing test equipment provided for accelerated testing, in a V-groove arrangement, so that wear was on two narrow wear tracks. Other techniques have included Rutherford backscattering, X-ray photoelectron spectroscopy, profilometry, optical microscopy, nanoindentation hardness, and white light interferometry. The balls were implanted with C-ions at 150 keV to a fluence of 1.1 x 10(17)/cm(2). The collection of samples had unanticipated, preexisting, defects called ''C-cracks'' in the surfaces. As a result, failure rate of the control group was unacceptable. None of the ion-implanted samples experienced failure in 150 h of testing. The probability of randomly selecting six samples from the control group that would perform this well is about 5%. Therefore, there is good probability that ion implantation improved performance. Possible reasons are discussed. Analytical techniques have been used to characterize ion implantation results, to characterize wear tracks, and to characterize microstructure and impurity content in possible relation to C-cracks.

[发布日期] 1997-05-01

[效力级别]  Proceedings Paper