Papers by Keyword: Surface Modification

Abstract: This manuscript presents a novel instant additive for elastomeric polymers, specifically focusing on the modification of synthesized mesoporous silica using carbonyl telechelic natural rubber (CTNR). The surface of mesoporous silica particles was modified using a two-step approach. In the first step, a strategy involving the grafting of 3-aminopropyltriethoxysilane (APTES) onto the silica particles was employed. Subsequently, in the second step, a Schiff's base reaction was carried out between the aldehyde functional group of CTNR and the amines on the modified silica surface. The grafting percentage achieved through this process was determined to be 4.70%. This novel instant additive has the potential to enhance the properties and performance of elastomeric polymers by leveraging the unique characteristics of CTNR and the mesoporous silica surface. Further investigations and applications of this additive can contribute to advancements in the field of elastomeric polymer materials.

Abstract: This study reviewed the synthesis of Titania with different shapes in the presence of cetyltrimethylammonium chloride (CTAC) as the famous stabilizer for directly altering the morphology and dimensions. These CTAC stabilizers usually provide the synthesis of Titania with a narrow size distribution and mostly single-crystalline structures in high yields. Many papers on the synthesis of Titania are available. However, only a few articles focus on the synthesis of Titania using CTAC as the stabilizer. The general rule for the shape transformation of Titania by CTAC stabilizer can be easily summarized based on the literature during the last ten year from https://www.sciencedirect.com/ as the data source.

Abstract: Due to the strong inhibition of drilling fluid, many polymer fluid loss additives can not play their role. Therefore, it is necessary to develop some water loss reducing materials that can withstand the strong inhibition environment. In this paper, the surface of asbestos fiber was modified and treated by indoor experiments. The physical and chemical properties of the obtained drilling fluid treatment samples were evaluated to optimize the appropriate amount of reagents used for surface treatment of asbestos. Subsequently, the drilling fluid performance of the obtained treatment agent samples were evaluated at different temperatures to analyze the effect of temperature on the drilling fluid performance. The surface of asbestos fiber was modified by adsorbed cationic surfactant CTAC which better solved the problem of entanglement of asbestos fiber in drilling fluid. The mechanism of the action of the surface of asbestos fiber was analyzed by scanning electron microscope observation experiments. Subsequently, different amounts of modified asbestos fiber was added to the drilling fluid and the performance of drilling fluid was evaluated at different temperatures. The experimental results showed that the modified asbestos fiber reduced the filtration loss of drilling fluid and still maintained good filtration loss reduction effect at 200°C.

Abstract: The work is devoted to the solution of the actual problem of waste management and its use for obtaining useful technical products, in particular, special purpose plastic lubricants. The research has been conducted on the use of spent sorbents after complex adsorption purification of industrial wastewater from Cu²⁺, S^2– and HS^–-ions in the composition of plastic lubricants. The composition of the latter includes a solid modified surface of sorbents [(activated carbon + kieselguhr) + CuS + S] and regenerated industrial oil I-40A. High operational properties of plastic lubricants are provided by modification of the solid surface of the components, on which there are active centers for chemisorption. The surface modification of activated carbon has been carried out in order to obtain [Cu(µ-S₅)]₂ or CuS₂ as possible equivalent substitutes for MoS₂. It was established that the chemical interaction of the pentasulfide anion and the copper (II) cation ends with the formation of a planar six-coordinated chelate center CuS₄(Н₂О)₂ on the surface, followed by its destruction and the formation of copper (II) sulfide and elemental sulfur. Activated carbon acts not only as a sorbent, but also as an active catalyst of topochemical reactions on a solid surface. Modification of the kieselguhr surface is caused by the presence of active centers on its surface – silanol groups –OH, which are subject to esterification. The developed plastic lubricants provide the necessary operational properties of heat-resistant industrial lubricants.

Abstract: Magnesium alloys are suitable biological material because of its favourable mechanical qualities, high biocompatibility, and biodegradability. However, it has poor corrosion resistance and has rapid dissolution in the corrosive environment which will weakens its mechanical characteristics. The surface characteristics of magnesium alloy must thus be changed using a suitable surface modification technology, such as micro arc oxidation (MAO). This article examines recent developments and advancements in biodegradable surface coatings applied to magnesium alloys. It was observed there are four steps of MAO process, the formation of a thinner and denser barrier, commencement of oxides in bare Ca-Mg matrix following the presence of sparks; the horizontal expansion of the oxide layer, and finally thickening of MAO coating. It was observed that characteristics of MAO coating can changed by varying electrical parameters like duty cycle, current density, type of power output, frequency, and processing time. It was noticed that when all other factors are held constant, duty cycle, processing time, and frequency primarily effect the coating's porosity, number of cracks and thickness, which in turn influences how well the coating performs. DC, AC, pulsed bipolar, and pulsed unipolar, are the four categories into which the current regimes are classified. It was found that, unipolar current mode MAO coatings found to be rough, highly porous, and vulnerable to microcracks due to stronger spark discharge. MAO coating produced in a bipolar current type of mode have larger pores but are more uniform in thickness and compact. It was noticed that the in-vitro cell assays showed cells L929 on the Ca-P coated Mg alloy to have considerably good adhesion, a high growth rate, and strong proliferation (p 0.05). In other words, the cytocompatibility was greatly enhanced by the Ca-P coating. It was discovered that the Ca-P coated Mg alloy improved cell responsiveness and encouraged early bone formation at the implant/bone interface by both conventional pathological examination and immunohistochemistry investigation. The Ca-P coating was found to be an effective method for raising the surface bioactivity of Mg alloy. It was also observed that the calcium phosphate coating deposited by MAO process improve surface biomineralization which is the main mechanism behind bioactivity. Functional groups that are present on surface engage electrostatically through calcium and phosphate ions from solutions to start the biomineralization process. Calcium phosphates have excellent biocompatibility and are quite comparable to the mineral makeup of bone. The current study aims to investigate the bioactivity of calcium phosphate coatings and the characteristics of magnesium and its alloys.

Abstract: The technology of producing stable electrochromic anode nanocomposite thin film coatings based on nickel oxide (II) has been developed, which are used as active layers for modulating light flux in the manufacture of various technical devices. The method involves introduction of carbon nanoparticles (carbon-containing particles) into outer layers of nickel oxide (II) thin films obtained by gas-phase deposition under conditions of cathodic polarization in potentiostatic mode in aqueous media containing water-soluble hydroxylated fullerene derivatives - fullerenol С₆₀(ОН)₂₄, without change of their optical density in the initial state. The technology of the method realization allows to effectively change electrochromic properties of nickel oxide (II) thin films and to obtain a nanocomposite, which is a matrix of a thin layer of nickel oxide (II), doped with carbon nanoparticles, with increased contrast and having the ability to maintain a colored state after switching off polarization under open chain conditions for a long time without energy consumption in solution and in air, i.e., characterized by an “optical memory effect”.

Abstract: Bismuth ferrite nanoparticles were successfully synthesized by the co-precipitation method and modified by polyethylene glycol (PEG) 4000. X-ray diffraction patterns showed a sillenite structure of bismuth ferrite (Bi₂₅FeO₄₀) with a crystallite size of 35.0 nm and the new phase appeared after surface modification. The new phase was Bi₂Fe₄O₉. Crystallite size increased after surface modification of nanoparticles with PEG. The highest increase of crystallite size after surface modification with PEG was 40.1 nm. Transmission electron microscopy images showed that samples before and after surface modification were polycrystalline and still agglomerated. Spectra of Fourier transform infrared showed the presence of C-O stretching at 1080 cm^-1 and C-H bending vibration at 1342 cm^-1 in the bismuth ferrite/PEG sample, which did not appear in bismuth ferrite sample. The magnetic measurement indicated the weak ferromagnetic properties of the samples. Saturation magnetization did not appear after a maximum external magnetic field (15 kOe) was applied. The maximum magnetization of nanoparticles was 0.5 emu/g and tended to decrease to 0.2 emu/g after surface modification with PEG. Optical properties analysis showed a shift in the maximum absorption peak of bismuth ferrite nanoparticles towards a lower wavelength (blue shift) after surface modification of the nanoparticles. The specific absorption rate (SAR) value of nanoparticles increased by increasing an alternating magnetic field (AMF) strength. The SAR values of bismuth ferrite nanoparticles were 48.8, 61.4, and 84.4 mW/g and decreased to 32.0, 45.2, and 83.3 mW/g after surface modification at the AMF strength of 150, 200, and 250 Oe, respectively.

Abstract: Investigation results of HA/TiO₂ bioceramics coating on the Ti-6Al-7Nb alloy by MAO process were presented. The voltages of 300-500 V. In the electrolyte solution contain (HA=6g/l, EDTA=3g/l, NaOH=8g/l, and KOH=1g/l) are used. The coating characteristics are identified by using field emission scanning electron microscopy (FESEM), (EDX), atomic force microscopy (AFM) and the resulted phases are identified by X-Ray diffraction (XRD), mechanical test (microhardness, and wear). The electrochemical test in the Ringer’s solution using a potentiodynamic polarization tests. The results of the tests showed the possibility of deposition of a composite nano ceramic layer was obtained from hydroxyapatite (HA) with TiO₂ were observed with increased voltage increased thickness layer and concentration of HA and decreased porosity, The identical dependencies of changes of the coating thickness with increase voltage and time. The best results were obtained in terms of hardness (368.1HV) and wear resistance equal to (4.33×10^-7) for 400V&15min. Improvement corrosion resistance equals (87.4%).

Abstract: Herein, Ti-6Al-4V alloy was remelting by high-energy laser, the influence of laser energy density of mobile laser source on the evolution of solidification structure of Ti-6Al-4V alloy was studied, and the changes of relevant service performance of Ti-6Al-4V alloy after laser-remelting were explored. The results showed that there were four distinct regions: overheated zone, melting zone, heat-affected zone and substrate zone in Ti-6Al-4V alloy after laser remelting. The overheated zone and melting zone were dominated by primary α phase and secondary α phase, and a heat-affected zone was dominated by β phase. With the increase of laser energy density, the depth of molten pool and the range of melting zone in Ti-6Al-4V alloy increased, and the crystal phase distribution and grain size changed significantly. Laser-remelting Ti-6Al-4V alloy could still maintain a good passive state in the potentiodynamic polarization curve test, and the optimal laser power during remelting was 1200 W. This study proved that the crystal phase composition and grain size during the solidification process after laser-remelting were a key factor affecting the service performance of Ti-6Al-4V alloy.

Abstract: The mechanical properties of grinding-tools relies highly on adhesion between the abrasive particles and the bonding phase, generally composed of organic rubber or resin materials. The surface modification of abrasive particles represents an industrial alternative to improve the connection with the bonding phase material. However, increasing the roughness of abrasive particles is a challenging process because of their high chemical stability. In the present study, three different approaches are investigated to modify the surface of industrially used alumina abrasive particles. Chemical erosion under harsh acidic and alkaline conditions, and hydrothermal deposition of aluminium-based coatings were used for the surface modification of the abrasive particles. The chemical stability of alumina particles was demonstrated by the chemical etching while the succesufull surface deposition of AlOOH crystals modified the apparent roughness of the processed powder particles. Morphological changes after each treatment were studied by scanning electron microscopy and the phase composition was confirmed by X-ray diffraction.