The Influence of Silicon Dioxide on the Stability of the Phase Composition and Mechanical Properties of Alumina-Toughened Zirconia-Based Ceramics

Technical Physics - The influence of SiO2 impurity (with a concentration varying from 0 to 10 mol %) on the stability of tetragonal ZrO2 (t-ZrO2) and on a set of micro- and macromechanical...     

Sorption of butane, propane, ethane, methane, and carbon dioxide on asphaltene

Isotherms of sorption of butane, propane, ethane, methane, and carbon dioxide on an asphaltene sample of known elemental composition were measured. The effect of the pressure and temperature on the shape the sorption isotherms for all the adsorption systems studied was examined. The values of the initial heat of sorption were determined and compared to the energies of interaction of the molecules with asphaltene. The results obtained suggest that asphaltene is a swellable amorphous sorbent.     

Electron paramagnetic resonance in a subsystem of structural defects as a factor in the plasticization of NaCl crystals

A change in the macroplastic deformation rate and an increase in the travel distances of edge dislocations are observed in NaCl single crystals placed in crossed dc and rf magnetic fields. The magnetic-field frequencies at which softening maxima are observed correspond to the resonance frequencies of transitions between Zeeman sublevels in paramagnetic complexes of structural defects. Pis’ma Zh. éksp. Teor. Fiz. 68, No. 5, 400–405 (10 September 1998)     

Radio-frequency paramagnetic resonance spectra, detected from dislocation displacement in NaCl single crystals

Results are reported here of a study of the resonance effect of a constant magnetic field and a variable magnetic field crossed with it on the rate of macroplastic deformation and motion of edge dislocations in NaCl crystals. The frequencies of the variable magnetic field at which the maximum variations in the plasticity of the crystals are observed correspond to the resonant frequencies for transitions between the Zeeman sublevels in paramagnetic complexes of point defects and complexes consisting of a point defect and a dislocation. Analysis of the radio-frequency spectra obtained enabled us to establish the role of intercrystal reactions in the formation of the mechanical properties of the crystals. Fiz. Tverd. Tela (St. Petersburg) 41, 1778–1784 (October 1999)     

Beta-induced decrease in the content of the Si-II,Si-XII,Si-III,and α-Si silicon phases formed under an indenter

Physics of the Solid State - Volumes of the metastable Si-II, Si-XII, Si-III, and α-Si silicon phases in a locally deformed (Berkovich pyramid) region of unirradiated and beforehand irradiated...     

The influence of low-intensity beta radiation on crack susceptibility under indentation of silicon

The dependence of the lengths of radial cracks formed during indentation of silicon single crystals on the depth of imprint has been studied using electron microscopy. The influence of low-intensity (I = 10⁵ cm⁻² s^–1) beta radiation on the crack susceptibility during indenter penetration to a depth of ∼2.5 μm has been revealed.     

Effect of electric fields on the dynamics of silicon microhardness changes induced by low-intensity β irradiation

Decelerating effect of electric fields on silicon microhardness changes induced by low-intensity (I = 10.4 × 10⁴ cm^?2 s^?1) β irradiation has been revealed. The threshold character of the electric field effect is found (the effect is absent at electric fields E < 350 V cm^?1).     

Multistage radiation-stimulated changes in the microhardness of silicon single crystals exposed to low-intensity β irradiation

Radiation-stimulated and postradiation changes in the microhardness of silicon single crystals exposed to irradiation with a low-intensity flux of β particles (I = 9 × 10⁵ cm^?2 s^?1, W = 0.20 + 0.93 MeV) are studied. It is established that the inversion of the radiation-induced plastic effect occurs at a characteristic irradiation time τ_c = 75 min; i.e., irradiation of silicon single crystals for a time τ < τ_c leads to nonmonotonic reversible hardening, whereas nonmonotonic reversible softening is observed under irradiation for a time τ > τ_c. It is demonstrated that there exists a correlation between the nonmonotonic dependences of the microhardness and the concentration of electrically active defects at acceptor levels with energies E _c ? 0.11 eV, E _c ? 0.13 eV, and E _c ? 0.18 eV on the irradiation time.     

Strength Properties of Zirconium Ceramics with Silica Additives Hardened with Alumina

Physics of the Solid State - The effect of Al2O3 and SiO2 admixtures on strength properties of calcia-stabilized zirconia ceramics is studied. Optimal ratios of the components of CaO–ZrO2 +...