In Situ Friction and Wear Measurements of Ion Implanted 304 Stainless Steel in Nitrogen and Oxygen Ambients

摘要

The dual ion implantation of Ti and C (4.6 x 10 sup 17 Ticm sup 2 at 180 keV followed by 2.0 x 10 sup 17 Ccm sup 2 at 50 keV) into 304 stainless steel has been found to reduce friction and wear in vacuum, oxygen and air environments. This treatment produces an amorphous matrix with embedded TiC precipitates within the implanted layer. Unlubricated friction measurements and wear track analyses were completed in situ in a scanning Auger microprobe using a 440C pin at a Hertzian contact stress three times the bulk yield strength of umimplanted 304. In ultrahigh vacuum the friction coefficient was reduced from 1.2 to 0.6 to 0.8, while the wear track width decreased from 414 to 325 mu m at 5000 cycles. For partial pressure of 2.1 x 10 sup -5 Pa of oxygen, almost the same reductions in friction and wear were obtained as in air: ion implantation decreased the friction coefficient from 1.10 to .65 and the wear track width from 319 to 198 mu m at 5000 cycles, as compared to decreases of 1.0 to 0.5 and 255 to 190 mu m, respectively, in air. Such decreases were not observed in nitrogen ambients, although the results in nitrogen were similar to those in ultrahigh vacuum. Friction coefficients and the analyses of wear track compostions indicate that oxidation of the implanted layer during sliding is important for reducing friction. 18 refs., 2 figs., 3 tabs. (ERA citation 13:034339)