Получение и свойства керамических материалов на основе системы Al[2]O[3]-MgO

It is known that aluminum oxide is the most generally used ceramic material applied as structural, functional and biomaterial. Meanwhile, it is used not only in a high state and but also in a highporous state. To obtain the required functional properties it is alloyed by various oxides such as FeO, SiO[2], Y[2]O[3], MgO and others. What most interested us is the magnasium oxide (MgO), as it is well known that the MgO presence in the ceramics materials causes biological processes activation at the boundary "implant - bone". However, the introduction of MgO into sintered mixture may change technological regimes of ceramics production and as a result to the structure and properties of the material can be changed as well. The aim of this work is to study the influence of the concentration of the injected mixture into the sintered MgO in the amount up to 10 wt. %. onto porosity, shrinkage characteristics of the microstructure and mechanical properties of the sintered material

Микромеханизмы деформации и разрушении слоистого материала из титанового сплава ВТ6 при ударном нагружении

The paper studies the phase composition, microstructure. and mechanisms of plastic deformation and fracture under shock loading in a layered material obtained by pressure welding of VT6 titanium alloy sheets. Under shock loading at 20 and 196 {5}C, the material is delaminated into sheet piles and this changes their fracture rate. At fracture surfaces, the initial crystal structure experiences structural phase decomposition resulting in dynamic rotations. In crystalline sublayers of the fracture surfaces and delamination, the material is fragmented. The effects are more pronounced at T =-196 °С

One-dimensional manganese coordination polymers composed of polynuclear cluster blocks and polypyridyl linkers: structures and properties

The synthesis, crystal structures and magnetic properties of five new manganese compounds are reported. These include a linear trinuclear cluster [Mn(II)(3)(O(2)CCHMe(2))(6)(dpa)(2)]center dot 2MeCN (1) (dpa = 2,2'-dipyridylamine), a tetranuclear cluster [Mn(II)(2)Mn(III)(2)O(2)(O(2)CCMe(3))(6)(bpy)(2)] (3) (bpy = 2,2'-bipyridine), and chain coordination polymers composed of cluster blocks such as Mn(3), Mn(3)O, and Mn(4)O(2) bridged by 2,2'-bipyrimidine (bpm) or hexamethylentetramine (hmta) ligands to give ([Mn(II)(2)Mn(III)(2)O(2)(O(2)CCMe(3))(6)(bpm)]center dot 2EtOH)(n) (2), [Mn(II)(2)Mn(III)(2)O(2)(O(2)CCHMe(2))(6)(bpm)(EtOH)(4)](n) (4), and (([Mn(II)(2)Mn(III)(2)O(2)(O(2)CCMe(3))(6)(hmta)(2)]center dot EtOH)(n) (5). The magnetic analysis of the compounds was achieved using a combination of vector coupling and full-matrix diagonalization methods. Susceptibility data for compound 1 was fitted using a vector coupling model to give g = 2.02(1) and 2J/k(B) = -5.38(2) K. To model the trimer chain, we used vector coupling for initial values of J(1) and then diagonalization techniques to estimate J(2) to give g = 1.98(1), 2J(1)/kB = -3.3(1) K and 2J(2)/k(B) = -1.0(1) K by approximating the system to a dimer of trimers. The analysis of 3 was made difficult by the mixture of polymorphs and the difficulties of a three-J model, while for 4 an analysis was not possible because of the size of the computation and the relative magnitudes of the three couplings. Compound 5 was modeled using the same techniques as 2 to give g = 1.99(1), 2J(1)/k(B) = +32.5(2) K, 2J(2)/k(B) = -16.8(1) K, and 2J(3)/k(B) = +0.4(1) K. The combination of techniques has worked well for compounds 2 and 5 and thus opens up a method of modeling complex chains