Papers by Keyword: Surface Properties

Abstract: Catalytic reforming is one of the most significant processes in the field of petroleum refineries and catalysts as they are considered as the heart of these processes .this paper presents the utilization of Atomic scale microscopy (AFM) to investigate the morphological and the surface properties of two catalytic reforming catalysts that are used in Iraqi refineries (RG582 & PR9). This paper provides a new insight into the study of catalysts since reaction routs significantly rely upon the used catalysts and their basic properties such as morphology, topography, roughness, growth regime and grain size. Keywords: Atomic Force Microscopy (AFM), catalytic reforming catalysts (CRC), surface properties.

Abstract: There is presented the method of silicon dioxide obtaining by its extraction from silica-containing solution from nepheline decomposition with the acetone and ethanol help with organic phase subsequent gelatinisation. Structural and surface properties of the obtained SiO₂ samples were investigated. The specific surface area of the obtained samples depends on the preparation method and varies in the range from 559 to 626 m²/g. The particles average diameter varies in the given series of samples from 2.26 to 6.68 nm. It has been found that the use of extraction has no destructive effect on the SiO₂ specific surface area and maintains its original microporous structure.

Abstract: Novel liquid crystalline oligomers were prepared using different compositions of kink-structured aromatic dicarboxylic acids, aromatic diols, and 4-hydroxybenzoic acid via high-temperature polycondensation. The reaction products were characterized by Fourier transform infrared spectroscopy, differential scanning calorimetry, and polarized optical microscopy. As a result, the samples containing kinked units with phenyl or naphthalene moiety had a broad processing window limited by the melting process and the isotropization, whereas one based on diphenic acid was almost entirely in an amorphous state. The surface properties of the oligomers were evaluated by wetting measurements using a static contact angle analysis.

Abstract: Ion-plasma modification of polymers has many potential applications, in particular, in the development of biomedical products. Treatment of soft polymers can easily damage the surface; low-energy plasma and subsequent investigation of the structural and mechanical properties of the surface are required. Polyurethane is a widely used block copolymer. Subplantation of carbon ions heterogeneously changes the structural and mechanical properties of the surface (relief, stiffness, thickness of the modified coating), forming a graphene-like nanolayer. Uniaxial deformation of the treated materials in some cases leads to the damage of the surface (local nanocracks, folds). Materials have increased hydrophobicity, good deformability (valid for certain treatment regimes) and can find application in design of products with improved biomedical properties.

Abstract: This work focuses on the fabrication of film based on natural biopolymers for wound healing application. Alginate and chitosan were choosen because of their oustanding properties such as biocompatible, hydrophilic and non-toxic. Earlier, the biopolymer film was fabricated by using alginate 1% wt and chitosan 1% wt. solutions at volume ratios of 99:1 and 97:3. Next, the biopolymer film solution was cross-linked with 1M CaCl₂.2H₂O for two hours and later dried for 24 hours at room temperature. Then, the surface properties of the prepared biopolymer films were characterised via Field Emission Scanning Electron Microscopy (FESEM), Atomic Force Microscopy (AFM) and contact angle measurement. It was observed that the surface of the biopolymer film became rougher as the volume of the chitosan increases. This condition was confirmed with average surface roughness, R_A for biopolymer film with ratio of 97:3 resulted in higher values. Also it was found that the surface of biopolymer films were hydrophilic after the contact angle was less than 90°. This can be concluded that the biopolymer based on alginate/chitosan is a promising candidate for wound healing materials particularly with good surface properties for faster healing process at the wound areas.

Abstract: Friction Stir Processing (FSP) technology was wielded to output the Al7075/ Al₂O₃ surface composite. The effects parameters of processing method on particle distribution have been studied. The microstructure and mechanical characteristics of the samples were examined using the optical microscope, SEM and hardness examination. Acquired consequences, showed that Al₂O₃ particles were in a good interior distribution inside the basement. This technique produced excellent bonding between the surface composite and the base material. On other hand the surface hardness was increased about 25% as compared with the substrate. In addition, grain matrix refinement and enhanced particle distribution were obtained after each FSP pass. Also the dispersion of Al₂O₃ particles in the stirred area became more homogeneous and the average hardness improved by increasing the number of passes.

Abstract: Commodity polymers are a common part of everyday life. They consist mainly of polyolefins such as polyethylene, polypropylene. They are primarily used for ease of processing, cost and especially chemical resistance. The disadvantages of these polymers are low mechanical properties as well as temperature resistance. Any improvement in the mechanical properties can extend the application possibilities of the commodity polymers to the areas reserved for the construction polymers. This paper deals with changing two injection moulding process parameters - melt and mould temperature to high-density polyethylene (HDPE) surface hardness. HDPE hardness was measured using the method of Depth-Sensing Indentation (DSI) on three different instruments (ultranano-, nanoand micro-hardness tester). It has been found that as the melt and mould temperature increases, the hardness slightly increases.

Abstract: The article presents a method to obtain silica xerogels with developed specific surface based on nepheline concentrate acid decomposition in C₂H₅OH-H₂SO₄ system. It was found that the use of ethanol instead of water produces stable and steady silica gels. It is proved that the use of ethanol results in almost complete deposition of soda alum and aluminum potassium sulphate out of nepheline decomposition solution without its additional cooling, due to their extremely low solubility in alcohol solution. The morphology, structural and surface properties of synthesized xerogel sample with ~600 m²/g specific surface area (based on the analysis) were investigated; its mixed micro-and mesoporous structure was established. Electron probe microanalysis showed chemical purity of the resulting SiO₂.

Abstract: The main objective of the present study was to investigate the application of Box–Behnken design which is a type of optimization design of response surface methodology (RSM) to predict and optimize some aging condition of magnesium silica aerogel (MSA) for improving surface properties such as surface area, pore volume and pore size. Brunauer-Emmett-Teller (BET), Barrett-Joyner-Halenda (BJH), Fourier Transform Infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM) coupled with Energy Dispersive Spectroscopy (EDS) techniques, tap density method and helium pycnometer were used to characterize aerogels. The operating conditions were optimized as a function of the molar ratio of Mg:Si (0.35, 0.50 and 0.65), aging time (24 h, 60 h and 96 h) and aging temperature (50 oC, 70 oC and 90 oC). Lack of fit test indicates that the quadratic regression model was significant with the high coefficients of determination values for all three properties. Optimized aging factors for synthesis MSA with high BET surface area, high BJH pore volume and average BJH pore size were found to be 0.5 Mg:Si molar ratio, 79.62 oC and 61.51 h, respectively. Under these conditions, magnesium silica aerogels have great properties: 734 m².g^-1 BET surface area, 0.41 cm³.g^-1 BJH pore volume and 4.91 nm BJH pore size, 0.12 g.cm⁻³ density and 95 % porosity. Box-Behnken is useful optimization tool for production of nanoporous magnesium silica aerogel.

Abstract: Boride coatings on steels have an excellent combination of properties. They can significantly improve the hardness, the wear and corrosion resistance of steels. Boronizing of steels has been achieved using different methods such as pack cementation and paste boriding. On the other hand, fluidized bed technology has been successfully used in many surface engineering applications in the deposition of hard and / or corrosion resistant layers e.g. carburizing, aluminizing and chromizing. This method is simple, efficient and environmental friendly and is characterized by excellent heat and mass transfer, which results to improve quality of the as-produced coatings. As a result, fluidized bed technology can be considered as a useful alternative method for the production of boride coatings on steel substrates. In the present paper we used this method to deposit boride coatings on steels. The as-produced coatings were examined by means of optical microscopy, X-Rays diffraction, Vickers microhardness and pin on disk in terms of coatings thickness and morphology, phase formation and mechanical properties. It was found that they are characterized by good adherence and uniformity all over the substrate and showed improved tribological properties under dry wear conditions.