Study Of Ti/DLC And W/DLC Nano-Multilayers Fabricated By PIIID Technique

Using plasma immersion ion implantation and deposition (PIIID), Ti/DLC and W/DLC multilayer were synthesized on GCr15 and 2Cr13 steel. Diamond-like carbon (DLC), titanium, tungsten layers were synthesized by the pulsed cathodic arc plasma source in our PIIID facility. All multilayers have the same thickness of approximately 1.5μm, but its modulation period is varied from 50 to 400nm.The films were characterized by scanning electron microscopy (SEM), x-ray diffraction (XRD), micro-hardness, scratch and electrochemistry corrosion tests. The SEM result indicates that the as-synthesized multilayer has a good periodicity structure. However, the interface between neighbor layers is vague, which can be attribute to the effect of ion implantation. XRD results show that the Ti/DLC and W/DLC multilayers are both amorphous structures. The micro-hardness testing results reveal that the maximum micro-hardness of Ti/DLC and W/DLC multilayers lies at a large specific period. The minimal microhardness of Ti/DLC and W/DLC multilayers lies at a small specific period. Scratch test results show that the multilayer sturcture can improve the adhesion strength between the substrate and the surface modification layer. However, since the flake behavior of different multilayers is different, different multialyers should have different stress distribution. The tribological results show that Ti/DLC and W/DLC multilayers have a high wear resistance at a small specific period. The cut-through number of the Ti/DLC and W/DLC multilayers on 2Cr13 substrate exceeds 10000 r, whereas that of the single DLC film on 2Cr13 substrate is about 2000 r. It can be concluded that the multilayer not only maintains the low coefficient characteristic of the single DLC film, but also improves adhesion strength between the surface modification layer and the substrate. The electrochemistry testing results exhibit that the corrosion voltage of the GCr15 steel is increased by the multilayers. The maximum corrosion voltage of Ti/DLC and W/DLC multilayers have increased by 19.4 percent and 32.6 percent, respectively. For 2Cr13 steel, the corrosion resistant of the W/DLC multilayer at the specific period of 200nm 300nm and 400nm is improved slightly, whereas that of the Ti/DLC structure has nearly the same corrosion resistance of the substrate.