High-temperature oxidation of intermetallics formed by group IV transition metals with chromium

We have studied the oxidation resistance of chromium intermetallics: TiCr₂, HfCr₂, and ZrCr₂, in the temperature interval 873–1473 K with isothermal holding of the specimens for up to 20 h. We have shown that the intermetallics TiCr₂ and HfCr₂ are oxidized 2–3 times more slowly than pure titanium and hafnium, but more than 1–2 orders of magnitude faster than chromium at T≤1273 K and 4–6 times faster at 1473 K. In this temperature interval, the intermetallic ZrCr₂ is rapidly oxidized at an increasing rate as the heating temperature rises. The scaling resistance of intermetallics of Group IV d metals with chromium is determined by formation of scales in which the major role is played by the oxides TiO₂, HfO₂, and ZrO₂, with weak protective properties.     

Effect of composition and the conditions of production of the bronze-ferrochrome composite material on its mechanical properties

Conclusions The technological conditions of preparation of the BrO-FKh composite material have a strong effect on its mechanical properties. To ensure high stable properties, the porosity in the formation stage should not be lower than 25–30%.The mechanical properties of BrO-FKh composite are determined by the effect of the ferrochrome addition on the localization of strains in the bronze matrix.At a ferrochrome concentration of 4–6% the nature of the dependence of proof stress in tensile and compressive loading, and of relative elongation and impact toughness on the ferrochrome content changes. This is associated with the change in the interaction between the components of the material in loading.There is a direct relationship between the nature of interaction of the components of the composite material in loading and the set of the tribotechnical properties.Translated from Poroshkovaya Metallurgiya, No. 7(283), pp. 86–90, July, 1986.     

Synthesis and properties of ceramics in the SiC — B4C — MeB2 system

The effect of impurities and additives of titanium and zirconium borides on the structure and mechanical properties of SiC — B₄C ceramics over a broad temperature range has been investigated. The ceramics was fabricated by hot pressing without a protective medium. Introduction of borides is accompanied by improvement in all the studied mechanical properties at room temperature, and the nature of hardening of the ceramics is practically independent of the type of SiC powders used. At high temperatures, the mechanical behavior of the ceramics is determined by the impurity composition: the ceramics obtained using abrasive powders loses strength beginning at 600°C, while using powders with decreased impurity content makes it possible to preserve the strength of the material up to a temperature of 1400°C. Translated from Poroshkovaya Metallurgiya, Nos. 5–6(413), pp. 29–42, May–June, 2000.     

Solid Oxide Fuel Cell Anode Materials

Powder Metallurgy and Metal Ceramics - The solid oxide fuel cell is a promising element that efficiently converts fuel chemical energy into electrical and thermal ones. The paper offers a brief...     

Properties of Ni–Cr–Al Alloys Obtained by a Powder Metallurgy Method

Alloys of practically 100% density were formed by hot pressing mixtures of nickel, chromium and aluminum powders. The principal phases formed are solid solutions based on chromium, on nickel, and also the intermetallic NiAl. These correspond to phases in the phase equilibrium diagram of theNi Cr Al system. The strength and wear resistance of the alloys are determined by the ratio of phase components.