Stability of hydrogen absorption for composite materials based on hydrogenating intermetallics

On the basis of studies factors are established which reduce the level and stability of the adsorption activity of a TiFe-Ni composite such as interphase reaction of intermetallic with metal during composite sintering and the passivating effect of oxygen impurity in the metal phase. In order to reduce the effect of these factors to a minimum it is possible to recommend optimizing the amount of interphase surface in the composite and maximum refining of the metal phase with respect to oxygen.Institute of Materials Science Problems, Ukrainian Academy of Sciences, Kiev. Translated from Poroshkovaya Metallurgiya, No. 4(364), pp. 25–29, April, 1993.     

Stability of composite materials based on boron and silicon nitrides and carbides

Conclusions Tests on a number of refractory materials in molten borax with or without electrolysis have established that boron carbonitride exhibits the highest resistance to attack under these conditions. By employing boron carbonitride as lining material, it is possible to perform boronizing in a new, high-productivity electrolytic installation.Translated from Poroshkovaya Metallurgiya, No. 8 (68), pp. 60–65, August, 1968.     

Stress distribution in antifriction composite materials

Conclusions The optimum shape of hard inclusions in a composite material, irrespective of the magnitude of load and mode of its application to the surface, is a spheroid or ellipsoid of revolution. The characteristic linear size of a hard inclusion should be greater than the calculated diameter of a single spot of contact. If a composite material is to exhibit high fatigue strength, it is necessary to ensure that the spacing between its hard and wear-resistant inclusions is not less than (1.5–2)a (a is the characteristic linear size of the inclusions).Translated from Poroshkovaya Metallurgiya, No. 11(203), pp. 54–59, November, 1979.     

One-zone rolling of composite materials

The energy–force parameters of free rolling of a strip without its tension and rolling with one backward or forward creep zone in the deformation zone are compared. The limiting backward or forward tensions are determined, and the change in the linear sizes of a composite billet during deformation in a rolling mill is considered.     

Activated sintering of W-HfC composite materials

The features of consolidation of the particles during the activated sintering of tungsten powders with different values of dispersity (d _av = 2–3 and 0.8–1.0 μm) are investigated. Sintering was activated by introducing nickel additives (up to 0.5 wt %), tungsten nanoparticles (up to 30 wt %), and finely dispersed hafnium carbide (5–30 vol %) with subsequent milling in a vibrating mill. The uniaxial compaction of the samples has been performed under pressures from 50 to 1000 MPa, and sintering was performed in vacuum at 1850°C with holding for 1 h. It is shown that the additives of tungsten carbide increase the density of sintered billets and, in combination with dispersed hafnium carbide, tungsten-based composite materials with a grain size up to 2 μm can be obtained.