Structure and properties of the diamond–WC–6Co composite doped by 1.5 wt % of CrSi<Subscript>2</Subscript>

The influence of chromium and silicon on the structure of the diamond–WC–6Co composite doped by chromium disilicide has been studied at the meso-, micro-, and submicron levels. It is established that under the conditions of the structure formation of the diamond–WC–Co + CrSi₂ chromium and silicon do not dissolve in particles of diamond and WC carbide, they form a Co(W,C,Cr,Si) solid solution decreasing the energy of the stacking fault, which contributes to the Co_(fcc) → Co_(hcp) polymorphic transformation. Chromium interacts with atoms of carbon in diamond and WC carbide, as a result of which the graphite layer in the diamond/Co phase contact zone disappears and the Co₃W₃C carbide forms in the volume of the WC–Co-matrix. Chromium and silicon contribute to a good retention of diamond particles by the WC–Co-matrix and increase the ultimate strength in compression of the diamond–WC–Co+CrSi₂ composite.     

The macroscopic model of the densification kinetics in the nonisothermic sintering of powders

The densification kinetics of a powder system has been described by a relatively simple analytical expression, which consists of only two dimensionless parameters. The first of them has been shown to be equal to the ratio between the maximum rate of the linear contraction and the total contraction of the sample multiplied by the time, for which the densification takes place; the second has been found to be equal to the ratio of the time required for the attainment of the maximum contraction velocity to the total densification time. The densification rate vs. time diagram is given by a curve having one or two maxima depending on values of the parameters entering the model. The study has been aimed at modeling the densification in sintering hard alloy mixtures.     

Boundary waves in ferromagnetically ordered two-dimensional arrays of magnetic dots

The existence of surface modes localized at the boundary of magnetic-dot arrays with magnetization perpendicular to the plane of array is predicted. Numerical and analytic calculations show that the excitation energy of these boundary modes is above the continuum of modes propagating in the array.     

Experience with hot-briquetted iron at OAO Moldavskii Metallurgicheskii Zavod

The introduction of hot-briquetted iron in batch for steel smelting in arc furnaces is considered.     

Theoretical and experimental studies of the composition and reducibility of the dust from arc steel-melting furnaces

The chemical and mineralogical composition of the dust from electric gas-cleaning filters of the steelmaking furnaces at the Moldavian metallurgical works is studied. The conditions of effective removal of zinc and lead from the ASF gas-cleaning dust are determined.     

Permutation schedules

The optimal scheduling problem of parallel identical machines is reduced by the resource approach to optimal permutation scheduling of jobs. Permutation scheduling algorithms for this problem are given.Translated from Kibernetika, No. 1, pp. 81–83, 111, January–February, 1990.     

Evaluation of impulse signal reconstruction errors in multichannel recording

Results of computer simulation are presented. They allow evaluating the reconstruction errors of an impulse signal at the multichannel recorder output versus the accuracy of determining the phase shifts between channels and their gain.     

Electromechanical resonances of piezoceramic plates with spatially nonuniform distribution of polarization

A technique has been considered of producing nonuniformly poled piezoceramic plates. The formation of the resonance spectrum of such plates has been studied both theoretically and experimentally. Factors have been revealed that affect harmonic components of the spectrum and a possibility demonstrated of thereby controlling its form.     

Electron-phonon interaction and electron mobility in quantum-well type-II PbTe/PbS structures

Electron mobilities in PbTe layers were calculated, taking into account electron scattering by longitudinal polar optical phonons, for low-dimensional structures — multiple PbTe/PbS quantum wells, which are type-II structures. Comparison with the electron mobilities obtained from Hall coefficient and magnetoresistance investigations in undoped multiple PbTe/PbS quantum wells versus the magnetic field intensity showed good agreement between the computed and experimental results for these structures. Fiz. Tekh. Poluprovodn. 32, 739–742 (June 1998)     

Total gamma dose characteristics of CMOS devices in SOI structuresbased on oxidized porous silicon

The electrical characteristics of complementary metal-oxide-semiconductor (CMOS) transistors and ring oscillators fabricated in porous silicon silicon-on-insulator (SOI) structures are presented before and after gamma irradiation. P-channel SOI/MOS transistors exhibit a front-gate threshold voltage shift of -0.2 and -0.55 V after exposure to doses of 1 and 10 Mrad(Si), respectively, under floating bias conditions, which are different from worst case conditions. For n-channel transistors the corresponding values are -0.1 and -0.2 V. The additional bottom and sidewall B⁺ ion implants with a dose of 2×10¹³ cm^-2 are found to be effective to prevent leakage current along the n-channel transistor bottom and sidewalls. SOI/CMOS ring oscillators present a 40% higher speed in comparison with the same bulk CMOS devices and continued stable operation under a supply voltage of 3-5.5 V, for gamma irradiation up to 10 Mrad(Si), and an operating temperature ranging from 77 to 400 K