Papers by Keyword: Wettability

Abstract: Study of TiC interaction with low-and high-carbon steel is presented in this article. Was carried out interaction thermodynamic modeling in the temperature range of 900-1800 °C, which showed that titanium carbide would dissolve in melts with these compositions, regardless of melt’s carbon content at given parameters. The obtained thermodynamic results were verified by conducting an experiment with high-temperature complex in order to study substances interaction processes. The obtained experimental samples were studied with scanning microscope as well as structure and compounds composition, obtained as a result of experiment mentioned above.

Abstract: The paper investigates the effect of plasma treatment of basalt fiber on its wettability, which is determined by the ability to absorb water. As the treatment time increases the wettability becomes higher, up to 10 minutes. The wettability-treatment power dependence passes through a maximum. The highest value is observed at a treatment power of 0.6 kW both on the day of treatment and after a 5-day rest period. A further growth in power not only does not increase this value, but in fact decreases it. The retreatment after a 5-day curing period yields lower results, but remains sufficiently high. The highest wettability is observed at a treatment power of 0.6 kW, gas flow rate of 0.04 g/s, chamber pressure of 20 Pa, air/argon mixture (1:1) as plasma support gas. The strength of concrete specimens BST V40 P2 was tested with two treatment modes: in mode 1 the treatment time was 10 minutes, the treatment power was 1.5 kW; and in mode 2 the treatment time was 5 minutes, the treatment power was 0.6 kW, with the addition of plasma treated basalt fiber (0.5 and 3 mass percent). Concrete has the highest strength when basalt fiber (3 mass percent) is subjected to plasma treatment in mode 2. In addition, the strength increases by 18 mass percent in comparison with the reference.

Abstract: This research investigates the effect of surface roughness, water temperature, and pH value on the wettability behaviour of copper surfaces. An electron beam physical vapour deposition technique was used to fabricate 25, 50, and 75 nm thin films of copper on the surface of copper substrates. Surface topographical analysis, of the uncoated and coated samples, was performed using an atomic force microscopy device to observe the changes in surface microstructure. A goniometer device was then employed to examine the surface wettability of the samples by obtaining the static contact angle between the liquid and the attached surface using the sessile drops technique. Waters of pH 4, 7, and 9 were employed as the contact angle testing fluids at a set of fixed temperatures that ranged from 20°C to 60°C. It was found that increasing the deposited film thickness reduces the surface roughness of the as-prepared copper surfaces and thus causing the surface wettability to diverge from its initial hydrophobic nature towards the hydrophilic behaviour region. A similar divergence behaviour was seen with the rise in temperature of water of pH 4, and 9. In contrast, the water of pH 7, when tested on the uncoated surface, ceased to reach a contact angle below 90^o. It is believed that the observed changes in surface wettability behaviour is directly linked to the liquid temperature, pH value, surface roughness, along with the Hofmeister effect between the water and the surface in contact.

Abstract: The contribution of the present work is to experimentally evaluate the wettability of Ti6Al4V solid surfaces manufactured via Electron Beam Melting (EBM), an innovative Additive Manufacturing (AM) process. The wettability behavior was quantified via goniometer, measuring the contact angle between a carefully deposited liquid drop (distilled water) and suitable solid surfaces. In order to study the influence of orientation and location in the build chamber on such properties several specimens were EBM manufactured with different growing direction.

Abstract: In this work, titanium dioxide nanotubes (TNTs) were prepared by anodization method with carbon cathode rather than the conventional platinum electrode. The composition of electrolyte and the anodizing voltage was fixed as constant for this research. Carbon plate was used as the counter electrode and the anodizing times were varied for 5 h and 10 h. After anodization, the samples were further annealed at 450 °C to crystallize the as-produced TNTs. Phase composition and morphology were identified by XRD and FESEM, respectively. Wettability of the samples were examined using a contact angle instrument. The results showed that the annealed TNTs were anatase phase with average pore diameter and tube-length of 28.7 nm and 284.6 nm for 5 h, and 30.0 nm and 376.5 nm for 10 h, respectively. The differences in pore diameter and length of the nanotube samples were due to the effect of anodizing time. Wettability of both annealed TNTs was also affected by anodizing time. The surface modifications and wettability results suggested potential applications in biomedical fields.

Abstract: Wettability is one factor that influences the enhanced oil recovery. Water-wet surfaces are predicted increasing the oil recovery from the reservoir. Microcellulose has the potential to produce water-wet surfaces. In this experiment, two types of microcellulose were used with different particle sizes of 2.9 μm and 14 μm. Both types of microcellulose are then applied to the reservoir rock surface model, i.e the surface of bentonite which has been soaked in crude oil for one week at 60 °C. Contact angle measurement shows that there is a decrease in water-the reservoir rock surface model contact angle from ~ 90 ° to ~ 80 ° when applied microcellulose solution 0.5% w/w. The difference in microcellulose size causes a difference in contact angle of about 5° at microcellulose solution 2.5%. This shows the application of microcellulose on the reservoir rock surface model causing the surface to be more water-wet.

Abstract: The contribution is aimed at corrosion propertied and wettability of basic graded of stainless steel commonly used in medicine as a standard for construction of instruments and other applications. Samples of AISI 304 (1.4301) steel were chemical passivated by nitric acid and tested for corrosion resistance in environment of sodium hypochlorite (NaClO), which is commonly used for basic disinfection of surfaces or devices in hospital facilities. It was found that chemical passivation of stainless steel surface increases its corrosion resistance and lower corrosion rate. Passivation layer also shows more polarization resistance. The wettability of passivated surface was measured by sessile drop method. Wettability itself determinates effectivity of disinfection process as the surfaces with lower contact angle may be cleaned and disinfected with more efficiency. It was proofed that chemical passivation increases wettability by lowering contact angle of treated surface.

Abstract: This paper aims to comparison of corrosion properties of two titanium alloys with different grain size. These alloys are commonly used in implantology for manufacturing long term body hard tissues replacements. Surfaces of tested samples were also electrochemically anodized using fluorine ions rich environment: the main reason for anodization was to create surfaces with highly bioactive properties which can intensify healing process and result into better bonding between body tissues when they are used in implantology. It was found by direct electrochemical methods that difference of corrosion rate between anodized and non-anodized samples was not significant. Anodization results positively influenced decreasing of corrosion rate when samples were tested in aerated physiological solution (0,9 wt. % NaCl/water). Type of bonding between implant and surrounding tissue may be also predetermined by value of contact angle of tested sample and water droplet on its surface. This paper confirmed that anodization increases wettability of tested samples and lower the contact angle to ~60°. According to these results anodization process may be recommended as a profitable treatment for surfaces of tissue replacements made from titanium.

Abstract: The effect of surface topography in combination with chemical composition on hydrophobicity and static coefficient-of-friction between steel and ice was studied. Polished stainless steel blocks were etched to introduce a roughness, and further treated with octadecanethiol. Carbon rich inclusions, identified by energy-dispersive X-ray spectroscopy, and scratches acted as the exposure centers to promote etching. Due to heterogeneities in steel, rounded cavities and parallel troughs were found on the surface after etching. Etched blocks with a lowered surface energy were studied under various ambient conditions to determine the influence of ice temperature and humidity on the static coefficient-of-friction. Blocks modified with octadecanethiol showed improved hydrophobicity. Warmer ice conditions led to a lower friction, regardless of the surface modification.

Abstract: Due to the excellent properties such as high temperature resistance, corrosion resistance, good heat conduction and plasticity, MAX-phase materials have been considered as one of the candidate materials for cladding and coating material in liquid metal cooled fast reactors. In this paper, the evolution of surface structure and wettability of Ti₃SiC₂ under short-term LBE corrosion were studied experimentally. The samples were immersed in LBE with saturated oxygen concentration for 100, 300 and 500 h at 450°C. The surface and cross section morphology as well as composition distribution of corrosion samples were analyzed by metallographic microscope, scanning electron microscope (SEM) and energy dispersive X-ray fluorescence spectrometer (EDX). Meanwhile, five-point fitting method was used to determine the contact angle of raw and corroded samples at 450°C. The results showed that the surface smoothness of Ti₃SiC₂ samples degenerated after LBE corrosion. No stratification was observed in all corroded samples but the transition layer was found in the surface region of corroded samples and its thickness increased with the increase of corrosion time. In the sample corroded for 500 h, the transition layer near the matrix side tended to transform into stable oxidation layer. In addition, the increase of corrosion time will lead to the reduction of LBE wetting on the surface of materials, which can effectively affect heat transfer of the surface.