Development of the method of production of the ultrafine macrohomogeneous composite powder

ABSTRACT

A method of ultrafine macro-homogeneous composite powder – B₄C–ZrO₂ production using a planetary mill was developed. From the macro-homogeneous composite high-density ceramics, B₄C–ZrB₂ was produced by the method of reactive sintering (in situ) at 2000°C under the pressure of 41–42?MPa. The effect of ZrO₂ grain size and of its distribution in the matrix on the consolidation parameters, and the microstructure of the obtained ceramics was studied.     

Multifunctional hetero-modulus composites in the B4C-BN-TiC-SiC-C system

Experiments have been carried out to develop multifunctional composites with improved properties and structure for use in air turbines, ballistic armor, cutting tools and atomic reactors. For optimization of the sintering process, microstructure improvement and increased plasticity we used MgO, Y₂O₃ additives. The composites contained carbon fiber (S-242 L_av = 370 μm, d = 13 μm) the carbide stoichiometric composition was maintained. Sintering was by hot pressing (25 MPa) in vacuum in the interval of 1800-1900 °C with dwell time 5-7 min. Structural analysis proved the homogeneous structure of the composite. The properties satisfy ISO standards. In summary, H_V = 24 GPa, compressive strength = 2300 MPa, HRA = 94, bending strength = 500-600 MPa.     

Experimental study of the effect of condensation on the transition into the turbulent mode of flow in a descending film of liquid with an associated gas stream flowing around it

The results of an experimental investigation into the transition of a descending film of water into the turbulent mode of flow are presented, the film being accompanied by a stream of gas, either of the condensing variety (water vapor) or of the noncondensing kind (air).Translated from Inzhenerno-Fizicheskii Zhurnal, Vol, 20, No. 1, pp. 17–20, January. 1971.     

Influence of electron energy on the characteristics of electron-beam-pumped semiconductor lasers

The influence of electron energy on the characteristics of electron-beam-pumped GaAs lasers is studied experimentally. Increases in the electron energy lead to increases in output power and decreases in beam divergence. Above radiation-damage threshold, a degradation of the laser output with time is observed due to bulk defects created by the beam. These defects are partially self-annealing if radiation is stopped.