Kinetics of oxidation SHS of titanium carbide and titanium and chromium double carbide powders in air

Institute of Structural Macrokinetics, Russian Academy of Sciences, Chernogolovka. Translated from Poroshkovaya Metallurgiya, No. 6(366), pp. 51–54, June, 1993.     

Composite resistance materials based on silicides of refractory metals

Conclusions On the basis of the principle of compensation for thermal variations in electrical conductivity composites have been formulated consisting of two current-conducting components, viz., Nb, Ta, or Zr disilicide and zinc sulfide activated with silver or nickel. To obtain composite resistance materials of minimum TCR, it is necessary to choose compositions from the range of concentrations of current-conducting components in which the sign of the TCR changes.Translated from Poroshkovaya Metallurgiya, No. 7(211), pp. 45–47, July, 1980.     

Composite materials based on titanium nitride for high-speed friction units

Tribological properties are examined for composite materials based on titanium nitride under conditions of dry friction for a wide range of speeds (1–25 m/sec). It is shown that the composites have a high level of tribological properties, which may be better (by up to an order of magnitude) than the properties of known materials. These results are used in guidelines for prospective materials for high-speed friction units. It has been found that there is a necessary condition for the materials to be used in high-speed friction units in that there should be high adhesion strength for the films of oxidation products together with low tendency to adhesion interaction with the counterbody.     

Use of hard alloys based on titanium carbide as wear-resistant materials and cutting tools

Conclusions Grade KTS alloys can be used as wear-resistant materials and as tool alloys for machining unhardened steels.Translated from Poroshkovaya Metallurgiya, No. 5(173), pp. 94–97, May, 1977.     

Physicomechanical properties of a hard alloy based on titanium carbide and nitride

Translated from Poroshkovaya Metallurgiya, No. 10(322), pp. 37–39, October, 1989.     

Pressing of hard-alloy mixtures based on titanium carbide

Powder Metallurgy and Metal Ceramics -     

Application of SHS processes for in situ preparation of alumomatrix composite materials discretely reinforced by nanodimensional titanium carbide particles (Review)

Types and fabrication methods of discretely reinforced alumomatrix composite materials (AMCMs), the wide application of which is hindered by a whole series of unresolved problems, are reviewed. These problems are the high cost of both reinforcing materials and the entire production process of composites; a not always sufficient level of strength properties, especially at elevated temperatures; the distribution nonuniformity of reinforcing particles over the volume of the aluminum matrix; and insufficient bond strength with it. It is discussed what contribution can be introduced into the solution of these problems by applying in situ processes, particularly, the SHS process, in order to fabricate cast nanostructured AMCMs. This is shown in more detail by the concrete example of the Al–10%TiC composite discretely reinforced by nanodimensional titanium carbide particles.     

Composite materials with an intermetallic matrix based on nickel and titanium monoaluminides hardened by oxide particles or fibers

Hardening phase/intermetallic matrix pairs are chosen for composite materials (CMs) intended for long-term high-temperature operation. These materials must have high and stable mechanical properties during a long time at high temperatures and loads. The compatibility of the physicochemical and mechanical properties of CM components is estimated to choose hardening phase/intermetallic matrix pairs in which the matrix is represented by an alloy based on NiAl or TiAl monoaluminide and the hardening phase is a refractory thermodynamically stable oxide of a Group III transition metal M ₂O₃. The following two schemes are used to perform hardening of a CM with a matrix consisting of a TiAl or NiAl alloy by the most thermodynamically stable interstitial phases, i.e., refractory oxides, at temperatures higher than the operating temperature (T _op) of the IMM. The first scheme consists in creating Al₂O₃/TiAl CMs hardened by continuous single-crystal sapphire fibers using the impregnation of a bundle of single-crystal fibers with a matrix melt followed by directional solidification. The TiAl-based matrix in these CMs serves as a binder connecting oxide phase fibers and preventing them from fracture due to high adhesion forces between oxide fibers and the matrix and a high fiber/matrix interface strength. In the second scheme, Y₂O₃/NiAl CMs are produced by powder metallurgy methods, which include severe deformation by extrusion accompanied by the formation of deformation texture and subsequent recrystallization annealing. In these CMs, disperse refractory oxide particles stabilize grain boundaries in a recrystallized matrix material and lead to the formation of directional structures with coarse elongated grains and a low fraction of transverse boundaries. Al₂O₃/TiAl CMs containing 20–25 vol % hardening single-crystal sapphire Al₂O₃ fibers can operate at temperatures of 1000–1050°C (∼0.7T _m of matrix), which is 250–300°C higher than the maximum values of T _op of a TiAl-based matrix and 400-450°C higher than the maximum values of T _op of a Ti-based matrix. An Y₂O₃/NiAl composite with a directionally recrystallized structure of a NiAl-based matrix hardened by 2.5 vol % Y{ia2}O₃ particles can be recommended for operation at temperatures of 1400–1500°C ((0.8–0.9)T _m of matrix), which are higher by 100–400°C than not only T _op but also T _m of Ni superalloys.     

Reaction of titanium carbide with water

Summary Contrary to the generally held view that carbides of the transition metals of groups IV and V are inert with respect to water, the authors show on the example of titanium carbide that the carbides are decomposed by water, although the extent of attack is not more than 5–30 atomic layers, i. e., not more than 100–150 A.The hydrolysis of TiC proceeds according to the reaction: TiC+xH₂O CH₄ + TiO₂ · xH₂O.Methane is the principal constituent of the gaseous hydrolysis products, and consequently it is possible to regard carbides of the transition metals of groups IV and V as methane derivatives. Hydrogen evolution in both carbides of group V and nonstoichiometric carbides of group IV is believed to take place as a result of the presence of free electrons in the carbides. The complex polymer acid TiO₂ · xH₂O undergoes dissociation, which becomes intensified in the course of time and results in a rise of hydrogen ion concentration. TiC powder particles are negatively charged. With the results obtained it is possible to choose suitable dispersion media for such powder metallurgical operations as fine milling, slip casting, and others.Translated from Poroshkovaya Metallurgiya, No. 6(54), pp. 53–57, June, 1967.