Magnesium oxide is widely used as an adsorbent, catalyst, identifier of chemical and toxic pollutants, in water and gas purification processes. Mesoporous magnesium oxide powder has been synthesized by the method of deposition, spray pyrolysis and glycine-citrate-nitrate method, their crystal structure, microstructure, granulometric composition and adsorption properties have been studied. Optimal conditions for the production of magnesium oxide by the glycine-citrate-nitrate method have been determined, which make it possible to obtain a powder with average primary particle sizes of 12 nm and the smallest sizes of secondary particles starting from 70 nm. The influence of the method of obtaining nanostructured magnesium oxide powder on the physicochemical properties is established. High values of the total pore volume of 1.038 cm3 /g exhibited the MgO powder obtained by the precipitation method.
The process of modifying aqueous powder suspension materials (APS) based on solid epoxy film-forming agents with highly dispersed powders of magnesium oxide was studied: production by ChemPur (n-MgO – primary size of particles is 36 nm), and magnesium oxide synthesized by a template method from the concentrated bischofite solution (MgOlab – primary size of particles is 102.8 nm). It was shown that presence of active functional surface OHgroups in both samples of magnesium oxide leads to the formation of secondary structures: aggregates and agglomerates. The nature of the influence of the size of aggregates of MgO particles and the conditions of dispersion on the properties of protective coatings is established. The nature of the influence of particle size and dispersion conditions on the properties of protective coatings is established. Optimal properties of coatings based on APS, sedimentation and aggregative stability of suspensions are implemented only under the condition of effective mechanical dispersion in a bead mill, when the most intensive destruction of large aggregates of n-MgO up to 50–60 nm occurs. The distribution of nanoparticle agglomerates in APS at the micro level (700–800 nm) using the MgO-lab does not lead to a significant change in the properties of APS and coatings based on them.It is shown that the introduction of n-MgO into APS allows reduces the curing temperature of the coatings from 110 to 90–100 °С. It is caused by the increase in the density of cross-linking of the spatial structure of polymer. The strength of modified coatings upon impact and tension increases by 2 times in comparison with the base composition, which does not contain nanomodifier, during curing of coatings at100 °C. In comparison with the known water-borne epoxy paints and varnishes, APS compositions are one-pack, they are more technological in use, have a long lifetime (up to 12 months in comparison with the viability of known two-pack epoxies, 1-8 hours). Materials can be used in industry for the protection of metal products, both as primers and as independent coatings.
The conditions and the patterns of copper and nickel nanoparticles formation by direct reduction from aqueous solutions of their salts in nitrogen atmosphere were studied, and nanocomposite materials based on magnesium oxide and metal nanoparticles coated with protective oxide shell were obtained. The obtained materials are of interest as sorbents for the purification of aqueous media from toxic impurities, as well as catalysts in organic synthesis, in particular for the production of methanol from carbon dioxide. Phase composition, thermal stability, microstructure of nanocomposites, as well as their sorption properties, were studied. The powders of magnesium oxide and nanocomposites based on it were found to have high sorption capacities with respect to lead and chromium ions – up to 2989.0 and 499.9 mg/g, respectively.
In the present work the influences of thermal-baric effect in the process of nanostructured alumina and zirconia powders consolidation on structure and physical-mechanical properties of the composite ceramics have been investigated. The samples of ceramics have been prepared from nanostructured powders (ZrO 2-3 mol. % Y 2 O 3) and Al 2 O 3 in ratio from 100 : 0 to 20 : 80 wt. % in two ways: by static uniaxial pressing and by pulse pressing. Then part blanks were annealed in the temperature region 1560-1670 o C. During pulse process a crystal structure of samples was disordered, and monoclinic ZrO 2 lattice was partially deformed. After a heat treatment of a blank the crystal structure of metal oxides was restored. Ceramics of oxide powders with content 100-50 wt. % PSZ synthesized at the 1100 o С possessed a higher level of properties than one of active powders prepared at the 900 o C.
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