Metal-ceramic composite development based on its modelling results

The modeling (and its experimental verification) of packing and deformation of the composites consisted of aluminum-magnesium alloy AMg6, B[4]C powder and W nano-powder has been performed. The powder compositions were determined using discrete element modeling of the composite particles packing based on the particle size distribution functions of real powders. The models of maximum mixture packing densities have been rendered

Structural and luminescent characteristics of YAG phosphors synthesized in the radiation field

YAG:Ce, YAGG:Ce ceramics were obtained by sintering the oxide powders in the radiation field. The results of investigations of the structure, composition and luminescence of ceramics are presented. The luminescence characteristics of powders exactly correspond to the phosphors luminescence used in practice obtained by solid-state synthesis methods. It has been established that in the used radiation exposure modes the main factor determining the efficiency of the synthesis is the ionization density

Surface Modification of Diatomite-Based Micro-Arc Coatings for Magnesium Implants Using a Low-Energy High-Current Electron Beam Processing Technique

The present study showcases a novel effective technique for the surface modification of micro-arc diatomite coatings using low-energy, high-current electron beams (LEHCEBs). A variety of methods such as scanning electron microscopy, energy-dispersive X-ray spectroscopy, the X-ray diffraction method, scratch testing, the potentiodynamic polarization method, immersion testing in SBF, and flow cytometry have been used to study the coatings. During processing, the electron beams’ energy density ranged between 2.5–7.5 J/cm2. After the LEHCEB treatment, the surface morphology of the coatings changed completely. The corrosion resistance of the LEHCEB-treated coated samples increased significantly, as evidenced by the decrease in corrosion current to 4.6 × 10−10 A·cm−2 and the increase in polarization resistance to 1.4 × 108 Ω·cm2. The electron beam treatment also increased the adhesion strength of the coatings to the magnesium substrate by 1.8–2.5 times compared to untreated coatings. Additionally, biological studies have shown the high viability of the NIH/3T3 cell line after contact with the samples of the coating extracts

Hydrophobic–Hydrophilic Properties and Characterization of PIM-1 Films Treated by Elemental Fluorine in Liquid Perfluorodecalin

A direct fluorination technique was applied for the surface treatment of PIM-1 films in a liquid phase (perfluorodecalin). The fluorinated samples were analyzed by various instrumental techniques. ATR-IR spectroscopy showed that the fluorination predominantly takes place in methylene- and methyl-groups. Cyano-groups, aromatic hydrogens and the aromatic structure of the PIM-1 repeat unit were shown to be relatively stable at the fluorination conditions. XPS confirmed that the concentration of fluorine, as well as oxygen, in the near surface layer (~1 nm) increases with fluorination time. C1s and O1s surface spectra of the fluorinated PIM-1 samples indicated an appearance of newly-formed C-F and C-O functional groups. Scanning electron microscopy and X-ray energy-dispersive spectroscopy of the fluorinated PIM-1 samples showed an increase of the fluorine concentration at the surface (~0.1–1 μm) with the treatment duration. Analysis of the slices of the PIM-1 films demonstrated a decline of the fluorine content within several microns of the film depth. The decline increased with the fluorination time. A model of fluorine concentration dependence on the film depth and treatment duration was suggested. A change in the specific free surface energy as a result of PIM-1 fluorination was revealed. The fluorination time was shown to affect the surface energy (γSV), providing its shift from a low value (25 mJ∙m−2), corresponding to tetrafluoroethylene, up to a relatively high value, corresponding to a hydrophilic surface

Developing Effective ways Formed of Structure and Properties of Hard Metal Composites Modified by Nanoparticles

Приведены новые данные о влиянии добавок керамических наночастиц на свойства твердых сплавов WC-Co. Комплексное исследование твердых сплавов с использованием традиционных методов испытаний механических свойств в сочетании с металлографическими, электронно-микроскопическими методами и рентгенофазовым анализом позволили установить стабильные корреляционные связи между объемным содержанием наночастиц и средним размером карбидов, параметрами микроструктуры и прочностью твердых сплавов. Наночастицы, введенные в состав твердого сплава, способствуют уменьшению толщины металлической прослойки, и, как результат, обеспечивается увеличение прочности связующего и твердосплавного композита в целом. Обнаружено стабильное снижение среднего размера зерна карбидной фазы (вследствие блокирующего влияния наночастиц на процессы рекристаллизации). Результаты испытаний показывают, что модифицирование наночастицами способствует повышению основных конечных физико-механических свойств твердых сплавов: твердости, трещиностойкости, прочности на изгиб, модуля упругости, износостойкостиNew data about influence of ceramic nanoparticles additives on the hard metals WC-Co properties are received. Complex investigation of hard metal using suggested conventional mechanic testing methods combined with metallography, electron microscopy and x-ray phase analysis enabled to establish stable correlating links between volume content of nanoparticles whith average sizes of carbide and micro structure parameters and strength of hard metals. Nanoparticles introduced into a binder size decrease of the metal interlayer and therefore increase the strength of binder and composite as a whole. The reduction of the carbide grain average size was found out as well (owing to nanoparticles blocking influence on recrystallization). The test results display that the modification thought nanoparticles enables to improve the main final physical and mechanical properties of hard metals properties: hardness, fracture toughness, transverse rupture toughness, elastic modulus, wear resistanc

Developing Effective ways Formed of Structure and Properties of Hard Metal Composites Modified by Nanoparticles

Приведены новые данные о влиянии добавок керамических наночастиц на свойства твердых сплавов WC-Co. Комплексное исследование твердых сплавов с использованием традиционных методов испытаний механических свойств в сочетании с металлографическими, электронно-микроскопическими методами и рентгенофазовым анализом позволили установить стабильные корреляционные связи между объемным содержанием наночастиц и средним размером карбидов, параметрами микроструктуры и прочностью твердых сплавов. Наночастицы, введенные в состав твердого сплава, способствуют уменьшению толщины металлической прослойки, и, как результат, обеспечивается увеличение прочности связующего и твердосплавного композита в целом. Обнаружено стабильное снижение среднего размера зерна карбидной фазы (вследствие блокирующего влияния наночастиц на процессы рекристаллизации). Результаты испытаний показывают, что модифицирование наночастицами способствует повышению основных конечных физико-механических свойств твердых сплавов: твердости, трещиностойкости, прочности на изгиб, модуля упругости, износостойкостиNew data about influence of ceramic nanoparticles additives on the hard metals WC-Co properties are received. Complex investigation of hard metal using suggested conventional mechanic testing methods combined with metallography, electron microscopy and x-ray phase analysis enabled to establish stable correlating links between volume content of nanoparticles whith average sizes of carbide and micro structure parameters and strength of hard metals. Nanoparticles introduced into a binder size decrease of the metal interlayer and therefore increase the strength of binder and composite as a whole. The reduction of the carbide grain average size was found out as well (owing to nanoparticles blocking influence on recrystallization). The test results display that the modification thought nanoparticles enables to improve the main final physical and mechanical properties of hard metals properties: hardness, fracture toughness, transverse rupture toughness, elastic modulus, wear resistanc