Papers by Author: Sheng Hu Wu

Abstract: A series of diamond-like carbon (DLC) films with different Si concentration were prepared by changing the ratio of the number of Si-doped graphite target and pure graphite target. As the Si concentration in the thin film keep on increasing, the concentration of C-Si bond will increase leading to decrease of hardness and stress and increase of friction coefficient. In order to synthesize DLC films on metal substrates 3 types of interlayer have been made. The first and second interlayer is made up Ti/TiCx, and the second is thicker, the third interlayer is made up Ti/TiNx/TiNxCy, with the same thickness of the second. We also prepared DLC films with 6.7 at.% Si concentration on TC4 and Cr12 substrates with the third interlayer, and the thickness, hardness and fiction coefficients is about 0.652m, 4200Hv and 0.15, respectively. The adhesion of films had been greatly strengthened with a proper interlayer, and the value is more than 39N/mm2

Abstract: To overcome the low adhesion of hydrogen-free DLC films on metal substrates, in this studying, DLC films (0.9μm) were prepared with 3 types of interlayer (2 types of Ti/TiCx/DLC interlayer and 1 type of Ti/TiNx/TiNxCy/DLC interlayer) on different substrates (W18Cr4V, Cr12, GCr15, TC4, 40Cr, 9Cr18 and Cr18Ni9Ti). The internal stress of the films was calculated by the bending of substrate (Si(100)). It was found that it is as high as 3.9GPa, and part of the high residual stress of the DLC films was dissipated through a compound interlayers, and the thick films achieved, and the pull tests found that the adhesion has been highly strengthened with a proper interlayer. The films structure qualities were investigated by Raman spectroscopy and the results indicate that the films have the same structure properties which suggests that the properties of the DLC films can not been affected by substrates. The hardness is about 5000HV, defined by nanoindentation techniques. The frictional properties were investigated by reciprocal sliding tests and the friction coefficient was about 0.1, independent of their substrates. Thus our DLC films may have great potential applications in precision parts tribological application.