The Process Improvement And Wear Resistance Of Cr4Mo4V Bearing Steel By Ti And N Ion Implantation

This paper mainly studied the composition and structure of N, Ti, and N+Ti ionimplantation layer, and single-element implantation was the object of study to calculate theion implanter process performance, at last, analyzed the mechanism of ion implantation toimprove the friction and wear properties.By SIMS and XPS, the concentration distribution of the injected element were tested;XPS studied the valence state of the implantation element; GIXRD studied the phase structureof the implanted layer. Nano-mechanical test system were used to test the nano-hardness ofthe implanted layers. Based on the range of distribution theory, we calculated the quantitativerelationship between the name of the injection parameters and the actual injection parameters,diffusion rate of injection element, theoretical concentration distribution and the remaining ofinjection element. By using the ball-disc wear testing machine, we tested the Cr4Mo4V/Si3N4friction pair’s friction and wear properties before and after ion implantation, and at the sametime, based on the results of the analysis of the morphology, size and composition of the wearscar, tested the mechanism of ion implantation to improve the friction and wear properties.The composition and structure and nano-hardness results showed that, in the threeimplantation sample, N, Ti two elements all showed a non-standard normal distribution. Forthe N ion implantation sample, the N element’s implantation depth is250nm, the peakconcentration is11at.%, located at45nm, chromium nitride phase and the free N atoms werefound in the implanted layer. For the Ti ion implantation sample, the Ti element’s injectiondepth is60nm, the peak concentration is7at.%, located at11nm, titanium and titanium oxidewere found in the implanted layer. For the pairs elements ion implantation sample, the N peakconcentration displacement to60nm， the Ti element distribution did not changesignificantly,titanium nitride, chromium nitride and titanium dioxide were found in theimplanted layer. The presence of the second phase were all nanocrystalline form. Thenanohardness peak coordinates of the three groups implantation sample were respectively(14.1GPa,50.1nm),(12.9GPa,35.1nm),(14.0GPa,62.0nm). Combination of theconcentration distribution analysis, the nano-hardness of the implanted layer was proportionalto the concentration of N; In the two elements ion implantation sample, due to the too smallactual injected dose, the Ti was no significant improve nano-hardness of the implanted layer, but the effective range was broadened.The implanter process performance results showed that, in the initial stage, the frictionpair of the substrate was adhesive wear mechanism. for the Microwave Source-Implanter, theactual implantation energy was57.5%of the name of implantation energy, the actual injectiondose was60.1%of the name of implantation dose, the remaining of injection element was1.0×1017ions/cm2, N atoms’ diffusion rate was26.2%; For the MEVVA ion source-Implanter,the actual implantation energy was50.5%of the name of implantation energy, the actualinjection dose was17.8%of the name of implantation dose, the remaining of injectionelement was1.482×1016ions/cm2, Ti atoms’ diffusion rate was18.2%.The friction and wear mechanism analysis showed that, in the initial stage,the frictionpair of the matrix was adhesive wear mechanism and in the stationary phase, three-bodyabrasive wear was mechanism-based; Note N implantation sample, at the low coefficient offriction stage, were minor two-body abrasive wear and adhesive wear, later developed into aviolent two-body abrasive wear, friction coefficient increased; Note Ti implantation sample,similar to the N implantation sample, but because of the surface titanium oxide layer,inhibiting the development of two-body abrasive wear, low friction coefficient stage so thatto be maintained longer; Note the N+Ti implantation sample, that had both high hardness andtitanium oxide layer, combined the advantages of the two previous ones, so the friction andwear performance was the best.