Finely disperse powders of stabilized zirconia with flake particles

The possibility of using carbonic acid for the plasma chemical method of preparing finely disperse ZrO₂ powders with flake particles is investigated. The optimum parameters of the technological process and the basic properties of stabilized ZrO₂ recommended for the production of high-strength ceramics are determined.Translated from Steklo i Keramika, No. 12, pp. 12–14, December, 1995.     

Predicting the strength of needle-punched materials

A model is proposed for predicting the tensile strength of needle-punched nonwoven materials. The dependence of strength on structure is described by a complex parameter formed by the product of surface density and bulk density. The strength attained in needle-punching depends largely on the surface density of the material.     

Experimental investigation of critical heat flux under boiling in subcooled swirling flow under conditions of one-sided heating

Results are given of an experimental investigation of critical heat flux in a turbulent swirling flow of subcooled water under one-sided heating. The parameters of flow are varied in the following ranges: the pressure of water at the inlet, 0.7 and 1.0 MPa; mass velocity ρw, 1100 to 9900 kg/(m² s); flow swirl coefficient k = 0.19 and 0.37; the temperature of water at the inlet—20, 40, and 60°C; and the hydraulic diameter of the channel, 2.16 mm.     

Mechanical characterisics of needle-punched materials treated with heated air

A study is made of the relationship between the deformation and strength characteristics of needle-punched materials made from a mix of polyester and bicomponent fibers and treated with heated air. This type of treatment is very effective for obtaining materials with good initial tensile strength. However, the material’s resistance to deformation is preserved with relatively little elongation. Its strength increases only in the transverse direction.     

Mechanical and structural characteristics of needle-punched materials with the use of different needles

The feasibility of partially or completely replacing imported needles by Russian-made needles is studied. Different needles and combinations of needles were used for the stage in which additional punching is performed. It is shown that Russian-made needles can partially take the place of imported needles, but such a substitution will require closer monitoring of the depth of needle penetration.     

Effect of pressure on the phase composition of Li(Na)/W/Mn/SiO2 composites and their catalytic activity for oxidative coupling of methane

The phase state of Li/W/Mn/SiO₂ and Na/W/Mn/SiO₂ composites after exposure to high pressures (2.5 GPa at 500°C) and subsequent exploitation in oxidative coupling of methane (OCM) was studied. Comparison of the catalytic activity of the composites before and after exposure to high pressures indicates that the formation of Li(Na)/W/Mn/SiO₂ composites catalytically active for OCM is significantly influenced by high pressures.     

Metrological defects in gravitational experiments using test masses

It is shown that the experiments of Allais and Long and other gravimetric experiments contained signals of a nongravitational nature which the authors failed to take into account. Translated from Izmeritel'naya Tekhnika, No. 1, pp. 3–8, January, 1997.     

Influence of uniaxial extension of C01Mn2Si1 steel samples after heat treatment on the structural noise

In ultrasonic structure analysis, a new approach is proposed to the assessment of metal structure in terms of the amplitude ratio of the mean structural noise and the secondary Rayleigh wave. The change in structural noise in the uniaxial extension of C01Mn2Si1 steel is investigated. The influence of mechanical stress and the structural state of the metal on the structural noise is demonstrated. The parameters of the structural noise are related to the structural state of C01Mn2Si1 steel. Experiments confirm that the sharp drop in structural noise at the yield point offers a sensitive method of detecting structural changes in the metal. Hence, measurement of the structural noise may be recommended for the detection of an early stage of damage accumulation in the metal—the stage of microdefect accumulation.