Papers by Keyword: Adhesion

Abstract: This research is a continuing study on F9-filter development via Ag-TiO₂ coating to promote volatile organic compounds (VOCs) removal and antibacterial activity. Problems of poor adhesion and uniform distribution of coating material on the filter surface were observed, so the addition of a polymeric surfactant (PS), which behaves as both a binder and a surfactant, was applied in this study in order to solve such problems. Dip coated F9-filter samples with a selection of Ag-TiO₂ suspension were characterized and tested. Environmental scanning electron microscope was used to characterize uniform coating distribution on an air filter. Self-cleaning test was performed in accordance with ISO 27448. The results showed that Ag-TiO₂ with PS dip coating on air filters provide good adhesion and high uniformity. It is also found that self-cleaning capability of Ag-TiO₂ with PS coated filter is increasing with increasing of Ag-TiO₂ and PS concentrations. Within a scope of this work, only visible light can drive Ag-TiO₂ to undertake photocatalytic activity. Hence, improvement of Ag-TiO₂ coating on F9- filter is confirmed when PS is applied.

Abstract: Inner surface of tanks is subject to corrosion due to constant contact with aggressive medium. The greatest danger from the point of view of possible corrosion destruction of steel is water (bottom, lower belts of the tank) and gas-air mixture (roof, upper belt) due to saturation with aggressive components: hydrogen sulfide, carbon dioxide, salts. Failure statistics show that the main reason for the failure of oil tanks (about 70%) is the corrosive wear of the surface that comes into contact with the aggressive medium. The application of paint coatings on the internal surfaces of steel tanks for the storage of oil and oil products is an effective measure to reduce corrosion and increase the life of tanks. However, there are a great many coatings. From the experience of tank operation, paint coatings of the following types were selected to analyze the effectiveness of corrosion protection: XC-717, EP-0020, FL-777, VN-780. To select the paint coating of the inner surface of the tank, physical and mechanical parameters were determined and calculations of the corrosion rate of the tank walls for the above paint coatings were carried out. After physical and mechanical tests, it was established that the best values of the coating are EP-0020. Thus, it is recommended to use a EP-0020 coating as a passive protection of the inner surface to ensure the durability of the tanks.

Abstract: Dependence of mechanical properties and microstructure of asphalt concrete with mineral fillers made of natural zeolites and brown coal was established. Optimal formulations with improved physical and mechanical properties for operation in difficult soil and climatic conditions were proposed.

Abstract: An oral obturator is a prosthesis used for a variety of dental conditions to help patients regain their abilities after trauma, surgeries, or having congenital defects. It is commonly made from polymethyl methacrylate (PMMA) resin. Despite that, this resin appliance can give rise to a condition for microbial adhesion and colonization on the resin surface itself and the mucosa beneath. This can place patients at a greater risk of infection. Oral infections caused by Candida species are found to be more common, particularly in immunologically compromised patients and those with other conditions in the oral cavity that often include oral prosthetic appliances. Obturator resin incorporated with vanillin has been produced and shown to have antimicrobial properties against some bacteria and yeasts. The purpose of this study was to determine the adhesion of candida to vanillin incorporated obturator resin. The auto-polymerized resin samples (Orthocryl® EQ, Dentaurum, Germany) were prepared with different concentrations of vanillin incorporation (0.1%, 0.5%, and 1% vanillin w/w). All samples were coated with sterile saliva and incubated at 37 °C for 60 min. The adhesion assay was done with four species of candida (C. albicans ATCC 10231, C. krusei ATCC 14243, C. glabrata ATCC 15126, and C. tropicalis ATCC 1369). The resin samples were placed in a 24-well plate containing 10⁷ CFU/mL of candidal suspension and incubated in a shaking incubator (120 r/min) at 37°C for 2 h for candidal adhesion. Non-adherent cells were removed by washing with phosphate buffer saline (PBS) solution. The remaining adherent cells on the obturator resin surface were quantified by the WST Microbial Cell Counting Kit (Dojindo Molecular Technologies, USA). The Kruskal-Wallis test, followed by Dunn’s method, was applied for statistical analysis. The results showed that the addition of 0.5% and 1% w/w vanillin to oral obturator PMMA resin could significantly reduce the adhesion of all Candida species except that of C. krusei, for which a reduction effect was observed at 1 % vanillin. The percentage reduction of candidal adhesion on obturator resin varies from 9% to 35%, which was highest on C. albicans, followed by C. glabrata (24%), and C. tropicalis (21%). No reduction effect was observed at 0.1% vanillin on all Candida species. In conclusion, vanillin-incorporated oral obturator resin displayed a reducing effect on the adhesion of all tested Candida species. C. albicans was the most susceptible species, while C. krusei was the most resistant. The mechanisms of action could possibly be the aldehyde group of the vanillin structure that causes cell membrane damage, interferes with DNA, RNA, and protein synthesis, as well as enzyme activities within the yeast cell. This newly developed PMMA resin could be valuable for the prevention or as an adjunctive treatment for controlling oral candidal infection among patients who use oral obturators.

Abstract: The article considers the influence of the domestic rejuvenator Lux «ЕD-L» on the properties of bitumen and asphalt concrete. The influence of the rejuvenator on the origin bitumen properties, on the properties of bitumen after RTFOT hardening, and on the rate of bitumen hardening is performed. It is shown that the properties of bitumen hardened by RTFOT method are completely restored to the level of bitumen before technological hardening under the influence of the rejuvenator. The high rate of the adsorption of additive by bitumen was proved with the evaluation of the bitumen adhesion to the mineral surface. An advantage of the rejuvenator Lux «ЕD-L» is a significant improvement in the adhesion properties of bitumen. Treatment of asphalt concrete mixtures conditioned according to the AASHTO R 30-02 method with the rejuvenator leads to the improvement of the quality indicators of asphalt concrete made on these mixtures.

Abstract: This paper studies the effects of fine waste glass powder content (WGP) on fresh and hardened properties of self-compacting repair mortar mixes (SCRMs). For this purpose, mortar mixes were prepared to replace cement with waste glass powder ranging from 0 to 30% at 10% interval and tested. Fresh properties were assessed using mini-slump flow and mini V-funnel. Hardened properties assessed for all mixes were water absorption (at 28-days of age), compressive and flexural strengths (at 7, 28 and 56-days of age). In addition, the adhesion between the repair mortar mixes and substrate was conducted using a 3-point flexural test on a composite prism (half mortar/half substrate) at 28 and 56-days of age. The results showed that glass powder had a negative effect on the workability of mortars. However, in the hardened state, it had a good influence on the strength development after 28 days, durability and adhesion of mortars with the substrate for a waste glass powder content not exceeding 20%.

Abstract: Aluminum Oxide thin films are potential candidate for anti-reflection, anti-soiling, and self-cleaning applications for solar cell panels, solar water heating panels, exterior windows of buildings, glasses, car windows, fabrics, and clothes. This paper reports on effect of chopping during deposition on the intrinsic stress and adhesion of Al₂O₃thin films deposited by electron beam evaporation. The kinetics of the growth and structure of the thin films is governed by adhesion. The durability and its wear are related to the certain extent adhesion of the thin film to the substrate. Effect of ambient aging on the adhesion and the internal stress in the films are also reported. The effect of chopping the thin film growth, phase change and presence of Al₂O₃ studied using scanning electron microscopy (SEM) and x-ray diffraction (XRD). The accumulation of strain energy in the thin film appears as internal stress and the binding of the vapor atoms to the substrates is referred to as adhesion. In this work, adhesion of thin films measured by direct pull off method and the internal stress is measured by interferometric method.

Abstract: In this work, the adhesion and corrosion resistance of TiN coating by magnetron sputtering on stainless steel substrates under different bias voltages conditions (-50 V and-100 V) was investigated. AFM was used for surface roughness and grain size analysis, XRD for phase identification, Rockwell C for adhesion and nanoindentation for hardness and elastic modulus. According to AFM the coating deposited at-100V bias had decreased surface roughness, the value decreased from 2.7 nm (for-50V sample) to 1.8 nm, this was due to an etching like process which occurs when ions with higher energies start hitting the surface. The coated samples came under HF1 adhesion parameter which is the highest class of adhesion in the model on the basis of Rockwell C adhesion test. nanoindentation hardness and elastic modulus results of-50 V and-100V were found to be 224 GPa and 182 GPa, respectively and the value of hardness, 16 GPa and 22 GPa, respectively. The corrosion behavior of TiN coatings were studied in 3.5wt. % NaCl solutions using Tafel Extrapolation, Cyclic Polarization and Open Circuit Potential. It was noted on the basis of these corrosion tests that, as bias voltage is increased, it leads to the formation of more densely packed, fine grained columnar structures with less pores, which decreases the chances of corrosion. .

Abstract: This article deals with the sealing of problematic cement-based building material and its adhesion and cohesion after exposure to water. Aqupanel cement board is chosen as a problematic material for the needs of this research. Furthermore, sealants are selected according to several criteria. These criteria include the manufacturer's recommendations on the suitability for use of cementitious substrates, affordability, and commercial availability for the average consumer. The selected sealants, the so-called primers, are then used for selected sealants. Test specimens are made of selected materials, which consist of two cement base plates, a primer, and an applied sealant. These test specimens with correctly matured sealant are further conditioned and tested according to the European standards ČSN EN ISO 8339 and ČSN EN ISO 10591. The results of these two tests are carefully recorded in the result tables and then evaluated and compared. These results show that for a tensile test without the use of water, it is necessary to apply a greater tensile force for the failure of the test specimen than for a tensile test after exposure to water. Furthermore, based on these results, we can say that polyurethane sealant is more resistant to tensile stress than acrylic sealant, for which the value of maximum elongation at failure of the test specimen is even several times higher.

Abstract: TBCs (Thermal Barrier Coatings) are multilayer structures usually consisting of a ceramic layer, known as top coat, arranged on a connecting layer, known as bond coat, which, in turn, is arranged above the substrate to protect. These structures are applied in hot section parts of gas turbine engines for providing thermal protection. During the component life, some oxidation end/or wear phenomena can occur, therefore the TBC is generally removed and then reapplied. To simplify the manufacturing process making it more cost effectiveness, the aim of this work is to study the possibility to repair a TBC system by removing the only damaged layer by using non-conventional processes and analyzing in detail the morphological roughness to ensure a good adhesion between the layers.