E. E. Fokina

Investigation of interactions in the TiH2-O2 system

Abstract Samples of the titanium oxyhydrides of composition TiH x O y , where x = 0.83–2.0, y = 0.1–1.4, were synthesized by interaction of titanium dihydride with oxygen at temperatures of 20–550 °C and pressures of 0.2–2.0 MPa and for each sample the electronic work function and the specific resistance were determined. It has been shown that the TiH 2 -O 2 system contains the suboxohydrides of compositions M 6 O, M 3 O and M 2 O, on the basis of the initial titanium dihydride lattice, where M is the initial titanium dihydride, analogous to the compositions which exist in the Ti-O 2 system.

Hydride and ammonia dispersion of metals

Chemical (hydride and ammonia) dispergation of Group II–V metals induced by hydrogen and ammonia in the temperature range of 100–500°C at a pressure of 0.5–2.0 MPa was studied. The phase transitions in the M-H2 and M-NH3 systems were investigated and conditions for metal hydride and nitride formation as highly dispersed powders were identified. The characteristic features of metal dispergation under the action of hydrogen and ammonia and the degrees of dispersity of the obtained powders were compared.

Chemical interaction between TiFe and ammonia

We have studied chemical interaction between the intermetallic compound TiFe and ammonia at temperatures from 150 to 500°C in the presence of NH4Cl as an activator of the process. We have derived schemes of the reactions involved and have shown that the use of ammonia for hydriding/nitriding enables the preparation of fine powders of TiFe and its hydride.

Hydrogenation of the intermetallic compound Zr2Ni

We have determined conditions for the preparation of hydride phases with the composition Zr2NiH∼5 by reacting the intermetallic compound Zr2Ni with hydrogen or ammonia and identified the products of the reaction between the intermetallic compound and ammonia in the temperature range 150–500°C in the presence of NH4Cl as an activator. The results demonstrate that the use of ammonia at 500°C leads to decomposition of the intermetallic compound and formation of zirconium hydride, zirconium nitride, and metallic nickel.

Hydriding of Mg2Ni in ammonia

The chemical interaction between the intermetallic compound Mg2Ni and ammonia in the presence of NH4Cl as an activator is investigated at temperatures from 100 to 450 °C, and the reaction scheme is presented. The results demonstrate that the use of ammonia for hydriding/nitriding the intermetallic compound makes it possible to prepare various magnesium compounds (Mg2NiH4, Mg3N2, and Mg (NH2)2) in a highly dispersed state.

Hydrides ScFe(Ni)2Hx: preparation and properties

Abstract The interaction of the intermetallic compounds ScFe2 and ScNi2 with ammonia was investigated at an initial pressure of ammonia of 0.6–0.8 MPa in the presence of 10 mass% (from the quantity of intermetallide entered in reaction) of NH4Cl as a process activator. The possibility of obtaining both crystalline hydrides of the intermetallic compounds and amorphous products of a reaction in a high-dispersed state was shown at various temperatures. It has been established that the decomposition of the intermetallides in ammoniacal medium occurs at ⩾450°C.

Hydriding of intermetallic compound Ti2Ni

Conditions of formation of the Ti2NiH3.3 hydride phase in the reaction of the Ti2Ni intermetallic compound with ammonia and hydrogen have been determined. The products of the reaction of the intermetallide with ammonia in the presence of the NH4Cl activator in the temperature range 100–500°C have been identified. It has been shown that the use of ammonia at temperatures >400°C leads to the formation of titanium nitride and nickel.

Reaction of the intermetallide ZrV2 with ammonia

The reaction of the intermetallic compound ZrV2 with ammonia within a temperature range of 150–500°C in the presence of NH4Cl as an activator of the process was studied. Depending on the reaction temperature, intermetallide hydrides and compositions of metal hydrides and nitrides or metal nitrides were obtained in the form of finely dispersed powders with particle sizes of less than 1.0 μm.

Hydrogenation of the Y2Fe alloy

We have studied reactions of the Y2Fe alloy with hydrogen at 100°C and lower temperatures and with ammonia at temperatures from 100 to 500°C. We have determined the composition of the reaction products and identified conditions for obtaining the YFe2H3.6 hydride and those of its decomposition in ammonia, resulting in the formation of yttrium and iron nitrides.

Preparation of hydrides of intermetallic compounds

Interaction of a series of intermetallic compounds with ammonia at 100–250°C and 1.5 MPa in the presence of promoter NH4Cl was studied. The optimal conditions of preparations of hydride phases have been determined. Properties of hydronitrogenation products of intermetallic compounds have been compared with those of direct hydrogenation products.