The ion beam assisted deposition (IBAD) method was chosen for preparing a carbon thin film with a mixing area on a substrate of Ti6Al4V titanium alloy. Nitrogen ions with energy 90 keV were used. These form a broad ion beam mixing area at the interface between the carbon film and the substrate. We investigated the chemical composition by the glow discharge optical emission spectroscopy (GD-OES) method and the phases by the X-ray diffraction (XRD) method. The measured concentration profiles indicate the mixing of the carbon film into the substrate, which may have an effect on increasing the adhesion of the deposited film. The nanohardness and the coefficient of friction were measured. We found that the modified samples had a markedly lower coefficient of friction even after damage to the carbon film, and they also had higher nanohardness than the unmodified samples. The increased nanohardness is attributed to the newly created phases that arose with ion implantation of nitrogen ions.
Multifunctional wear and corrosion resistant decorative nanostructured carbon-base coatings
were prepared by PACVD (Plasma Assisted Chemical Vapour Deposition) method on steel
substrates. As the multifunctional coating the carbon-base, particularly DLC (Diamond-Like
Carbon) nanolayer, was chosen.
For the deposition of adherent DLC coating on steel substrate a very thin Si-O-C interlayer
was applied in some cases. Deposition of DLC coating and Si-O-C interlayer was performed
using dc plasma without additional heating and with the HMDSO (hexamethyldisiloxane) and
methane as precursors.
During coating growth with increasing of thickness of DLC nanolayer the colour of nanolayer
is changed. Whole spectrum of attractive colours is obtained, what is possible to use to
decorative purposes. Effect of film thickness on colour is following: The reference specimen
(bare stainless steel) has a bright metallic sheen. In the order of increasing thickness, the DLC
films produced by PACVD have colours as follows: dark violet at ~75 nm; medium blue at
~130 nm; golden light at ~170 nm; deep rose pink at ~240 nm; golden brown at ~320 nm; and
soot black at ~1200 nm.
Decorative coatings must be adherent and hard for good wear resistance. Adhesion was tested
by scratchtester and microhardness was determined by nanoindentation. The microhardness
data were thickness-dependent, influenced by substrate. The highest measured value was 23
GPa. Tribology of the coatings was assessed by wet friction tests.
The effect of gamma irradiation and subsequent thermal treatment on the wear resistance and friction behavior of ultrahigh molecular weight polyethylene (UHMWPE) has been studied. Irradiation of the polymer was performed using a 60Co γ-emitter at laboratory temperature. Radiation dose 50 kGy was applied. Some irradiated samples were thermally treated at 150˚C for period of 30 min. and then slowly cooled to room temperature. A linear reciprocating tribometer was used to investigate the wear behavior of UHMWPE against Co-Cr-Mo alloy. The tests have been performed in unlubrication conditions. An important increase in wear resistance of the modified UHMWPE in comparison with the original material was proved. Besides wear rate the selected mechanical characteristics (friction coefficient, Young’s modulus, yield strength, fracture strength, and hardness) of original and modified samples of UHMWPE have been determined.
Mathematical models of composed high energy ion beam assisted deposition (IBAD) concentration profiles of implanted component in binary thin films are described. Yields of the backscattered ions and sputtering of the deposited component are considered. A Gaussian probability density is assumed to apply to the ion range distribution. The construction of concentration profiles of various shapes is considered. These profiles should of course be constructed based on continuous changes of the process parameters, but certain technical problems can arise with this continuous parameter changes. Therefore, it has been assumed that the changes to the process parameters are discrete and proceed in several steps. The resulting mathematical models are combinations of error functions. Mathematical models can be used as regression functions for the determination of some parameters, e.g., the sputtering yield. Based on the mathematical model the gradient concentration profile of nitrogen in the SiNx film was experimentally produced by the IBAD method, measured by Rutherford backscattering spectroscopy and compared with the mathematical model.
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