Structure and Certain Properties of Hot-Pressed Boron Carbide-Based Ceramic with Calcium-Silicon Additive

The influence which the composition of powder mixtures, the treatment conditions which the mixtures are subjected to, and the conditions under which the hot-pressed composite materials B₄C – (5-10 mass%) calcium-silicon are fabricated exert on the structure, nature of failure, and mechanical properties of these materials is investigated. Optimum properties are possessed by material containing 10 mass% of addition. It is shown that the structure, morphology, and dispersivity, as well as the nature of the distribution of the components that are added to the composite material (secondary phase) vary as the temperature of hot pressing changes. Maximal mechanical characteristics of the composite material (σ_bend = 560 MPa, K _1c = 4.7 MPa·m^1/2, HV = 37 GPa) are attained at hot-pressing temperatures in the range 2000-2100°C.     

Self-reinforced materials based on aluminum nitride

Powder Metallurgy and Metal Ceramics -     

Existence of the Solution to the Cauchy Problem for Nonlinear Stochastic Partial Differential-Difference Equations of Neutral Type

Cybernetics and Systems Analysis - The authors consider the existence of the solution to the Cauchy problem in the class of nonlinear stochastic partial differential-difference equations of neutral...     

Carbon activity in Fe-, Co-, Ni- and Mn-based melts at 1873 K

A method to determine the first order interaction parameters according to the data of the influence of alloying elements upon the carbon solubility in liquid metals has been developed. The calculated results for iron based melts have been found to be in a good agreement with literature data. The values obtained for Mn-, Fe-, Co- and Ni-based melts at 1873 K have been summarized in the series of linear equations depending on the number of alloying element in the periodical system. Calculated metal activity in binary Me-C (Me = Mn, Fe, Co, Ni) melts shows good agreement with literature data.     

Structure and Properties of B4C - SiC Composites

We have investigated how the composition, grain morphology, and method of preparing the starting mixture affect the processes that form the structure and phase composition of B₄C - SiC composites during hot pressing. We found that, depending on the composition of the initial powder mixtures, which is responsible for different mechanisms of consolidation of ceramic materials during hot pressing, the grain size of the main B₄C phase and its defect content as well as the nature of the SiC phase distribution within the material differ significantly. When B₄C - SiC composites with a low SiC content are made from initial B₄C - B₄Si - B - C powder mixtures those composites have a high cracking resistance because of their fine grain structure.__________Translated from Poroshkovaya Metallurgiya, Nos. 3–4(442), pp. 112–119, March–April, 2005.     

Nondestructive testing of the thermal resistance of Gann diodes during their manufacture

The results of an investigation of the thermal resistance of Gunn diodes at different process technology cycles of their manufacturing are considered.