Solid State Phenomena Vol. 199

Abstract: The aim of the work was the assessment of adsorption capabilities of selected animal mucins. In this work two animal mucins (mucin porcine stomach, type II and III), which were dissolved in phosphate buffered saline were evaluated. The tested materials, where the adsorption of glycoproteins takes place, were surfaces of two implantation materials: titanium alloy (Ti-6Al-4V) and 316L steel. The standardized samples of materials were immersed in solution of mucin II and solution of mucin III aseptically prepared) for: 10 minutes, 120 minutes, 1 day and 5 days. The UV spectrophotometry method was used for analysis of the mucin concentrations as a simple and effective technique. The obtained results clearly indicate that the tested surfaces are covered by the mucins used for experiments. However, quantitative analyses of adsorbed mucins did not show significant differences, both between tested materials, and mucins.

Abstract: Methodological aspects of fretting and fretting-corrosion research of metallic biomaterials are presented in this article. At the Faculty of Mechanical Engineering Technical University of Bialystok tribometer device was constructed to test the fretting phenomenon with flat-on-flat contact configuration [. Based on the results of published research the fretting regimes were established. Values of the amplitude of reversible movement were 80-120 µm, the frequency was 1 Hz [2] and the value of the pressure was 20 MPa. Fretting-corrosion tests in simulated biological fluids should be performed in the three-electrode system in presence of the reference electrode and counter electrode along with the working electrode to the potentiostat. It is important to leave the system loaded and immersed for about 30 minutes prior to testing the potential of the system. During that time system potentials are stabilized. After that, acquiring data for fretting corrosion should be started with measurement potential/time changes [. A better understanding of the fretting processes will largely eliminate its effects at the construction design stage.

Abstract: One way of obtaining new materials with different properties is to modify existing ones to improve their insufficient properties. Due to the fact that many of the useful properties of materials, including wear and corrosion resistance, friction coefficient and biocompatibility, depend on the state of the surface, modern surface engineering methods are especially helpful. They involve the deposition of the layers with tailored chemical composition and structure. In terms of medical applications, amorphous or nanocrystalline layers containing carbon, nitrogen, silicon and hydrogen appear to be the most suitable. They combine the beneficial properties of silicon carbide SiC and silicon nitride Si₃N₄, and thus exhibit a strong resistance to oxidation at high temperatures, high modulus of elasticity, low friction coefficient and wear resistance. However, silicon carbonitride compound is not stable thermodynamically in normal conditions and therefore it must be obtained by non-conventional synthesis. One of such method is Plasma Assisted Chemical Vapour Deposition (PACVD). The authors of this paper anticipate that the modification of titanium surface by SiC_xN_y(H) layers make them proper for use as materials for long-term contact with human body. It contains results of research on titanium Ti Grade 2 surface modification by deposition amorphous carbon layers doped with nitrogen (a-C:N:H) and silicon carbonitride layers SiC_xN_y(H). What is more, for IR analysis, in the same plasmochemical methods process obtain layers on monocrystaline silicon (001)Si. The layers were synthesis by PACVD with plasma generated by radio waves (RFCVD, 400 W, 13.56 MHz) for a-C:N:H layers and microwaves (MWCVD, 2 kW, 2.45 GHz) for layers containing silicon, carbon, nitrogen and hydrogen. During deposition process metallic surface were ion-etching by argon plasma. The layers were obtained from reactive gas mixture containing CH₄, N₂ or NH₃ for a-C:N:H layers and CH₄, SiH₄, N₂ or NH₃ for silicon carbonitride compound. In this process argon was used as an inert gaseous. Process conditions allowing obtaining good adhesive layer to the metallic substrate were specified. Obtained systems were subject for further research. Chemical composition of the materials were studied by SEM / EDS techniques with application ETD and BSED detectors. Compared images registered for titanium before surface modification and surfaces covered by a-C:N:H or SiC_xN_y(H) layers. More information about layers structure provided FTIR spectroscopy. Spectra FTIR was register transmition for (001)Si-layer and reflective for titanium-layer systems. Assessed the impact of different kind of substrate on the layers deposited structure. Operational properties of synergic layer-titanium systems were evaluated in the measurements of tribological parameters. This tests shown that silicon carbonitride layers have the lowest friction coefficient and the highest resistance to wear. Furthermore, it was possible, on the basis of the obtained result, to indicate directions the surface modifications ensuring optimization on their usable properties as medicine and another industries. In previous authors paper the layers were investigated in the aspect of possible application in medicine.

Abstract: The present paper describes the results of tests on the influence of selected self-made solutions of synthetic saliva on tribological characteristics of implant materials on the example of the Co-Cr-Mo alloy. The used saliva substitutes were prepared on the basis of gums (xanthan, guar, arabic and carob bean) dissolved in saline buffer. Analysis of the values of the coefficient of friction and the wear of the tested dental alloy in tested solutions was performed. Different values of the coefficient of friction were observed for friction pairs tested in individual solutions. Its lowest values were achieved during tests using xanthan gum with SDS (sodium dodecyl sulfate) addition, and the highest values were achieved for xanthan gum. As regards wear analysis, its lowest value was registered during lubrication with natural saliva. Among saliva substitutes, the lowest value of mass wear of dental alloy was observed in solution of xanthan gum, and the highest value was registered for carob bean gum. After friction tests, elements of the friction pair were subjected to microscope analysis using the Olympus BX61 optical microscope.

Abstract: The paper deals with a stationary heat conduction problem for a microperiodic, two-layered coating on a homogeneous half-space. The distribution of temperature and heat fluxes are obtained within the frame of the homogenized model with microlocal parameters [1,2, and within the framework of the classical heat conduction problem for a periodically layered structure. The influence of number of layers in the coating on the heat flux and temperature is analyzed.

Abstract: The paper presents investigation results of climatic as well as environmental factors influence on surface state of three-layer epoxy coatings. A three-year investigation documented substantial destruction of coating surface layers. In particular, a significant increase of aged coating surface roughness, evaluated on the basis of Ra and Rz parameters, was observed. Studies made with SEM corroborated a delamination as well as pigment and filler crumbling from surface layers of coatings. In the final period of ageing craters and superficial cracks appeared in the coating structure. Destruction of aged coating surfaces contributed to their gloss loss by over 98% (for light incidence angle α = 60^o) decreasing in this way coating decorative properties.

Abstract: The paper describes the application of high power direct diode laser (HPDDL), with a rectangular laser beam spot of size 1.8x6.8 mm, for the cladding of Ni-based alloy (NiSiB)+WC composite coatings. The laser cladding process was carried out with a direct injection of cladding powder into the melt pool. The influence of parameters, such as laser power beam (heat input) and WC particles size in the cladding powder on the coatings microstructure and wear properties was investigated. The microstructure and morphology of the coatings were assessed by optical and scanning electron microscopy. Wear properties of the coatings were investigated using abrasive and erosive wear tests. The results showed that a proper selection of laser cladding parameters provides non-porous coatings with excellent metallurgical bonding and a homogeneous distribution of WC particles. The dissolution of WC particles increases with the size of WC particles decreasing in the cladding powder and increasing the laser power level (heat input). The coatings containing WC particles in size range of 100-200 µm provide the highest wear resistance under erosive and abrasive conditions.

Abstract: The paper deals with the numerical and experimental analyses of functionally graded material structures which are represented by a surface layer of the steel sample hardened during the laser treatment process. A functionally graded parameter of the researched structure was assumed as the hardness value experimentally measured with the use of a Vickers hardness test method. The microstructure of the tested layer was also analyzed for the Vickers test verification. Two homogenization methods were used for the purpose of layer substitute properties for numerical calculations. The first one was to divide the FGM domain into a number of layers in the direction of material gradation and then apply a numerical homogenization method within each layer. The resulting material model describes the FGM as a composite of homogeneous layers. The second method was based on the Mori-Tanaka homogenization theory and was carried out with the use of Digimat software, which is the nonlinear multi-scale materials and structures modelling platform. Both methods were compared and showed good correspondence.

Abstract: The fibre-metal laminate specimens were connected with steel plates by means of the glue joints. The influence of the type of connection on composite mechanical properties (displacement vs. force characteristics) was analyzed. The glue joint between the laminate and the steel plate guarantees even distribution of the displacement during tests. The method of connecting laminates by means of glue joints leads to the connection with the smallest overall dimensions and weight. In the initial research the samples connected by means of different glues were tested.

Abstract: The paper concerns application of tribology achievements in operation of machines kinematic joints. The method of protective layers constituting on rubbing surfaces of kinematic joints elements were presented which minimize adverse effects of friction like motion resistance and wear. A method of protective antiwear and anti friction layers forming on rubbing surfaces of kinematic joints elements at the beginning of exploitation process is proposed.