Effect of severe plastic deformation on the microstructure and tribological properties of a babbit B83

The effect of severe plastic deformation carried out at room temperature by the methods of equal-channel angular (ECA) pressing and surface friction treatment (SFT) on the microstructure, rate of wear, and friction coefficient of a babbit B83 (11.5% Sb, 5.5% Cu, Sn for balance) has been investigated. It has been shown that severe plastic deformation that leads to a drop in the grain size of the babbit to 100–300 nm and to a strong refinement of particles of intermetallic phases (SnSb, Cu₃Sn) causes a considerable (twofold-fourfold) reduction in the rate of wear and a decrease in the friction coefficient of a steel-babbit pair under test conditions with lubrication at small (0.07 m/s) and enhanced (4.5 m/s) sliding velocities. As was shown by structural investigations performed with the use of scanning electron microscopy, this positive influence of severe plastic deformation on the tribological properties of the babbit is connected with the formation on the deformed-babbit surface of a developed porosity, which improves conditions for lubrication of the babbit-steel friction pair due to the action of the self-lubrication effect and thereby favors the retention of a stable regime of boundary friction of this pair. The formation of porosity is a result of the accelerated spalling of hard brittle intermetallic particles of SnSb and Cu₃Sn from the friction surface of the deformed babbit, which is caused by weakening and loss of the bonding of these particles with the plastic matrix (α solid solution based on tin) in the course of severe plastic deformation of the babbit. At the same time, under the conditions of dry sliding friction of the babbit-steel 45 pair, when a fatigue mechanism of wear of the alloy under consideration predominantly develops, this plastic deformation yields an approximately 1.6-fold increase in the rate of wear of the babbit. This increase is mainly due to numerous defects (microcracks) that are introduced into the babbit structure upon its severe plastic deformation and reduce the resistance of the surface layer of this material to the fatigue mechanism of wear.     

Modern Classification of the Rocks of Gabbro-Basalt Raw Materials Occurring in Russia

Based on the data of chemical analysis and on calculated petrochemical characteristics, the rocks from 48 deposits of gabbro-basalt raw materials native to Russia are assigned to specific mineral families and species corresponding to the Petrographic Code of the Russian Federation.     

Application of magnetic separation for modifying the composition of basalt raw materials

The results of studying the process of modifying the composition of basalt raw materials using the magnetic separation method are reported based on the example of basalt of the Myangdukha deposit (Arkhangelsk oblast). The chemical and phase compositions of magnetically enriched and magnetically depleted fractions have been determined by mass spectrometry and X-ray powder diffraction. The process of sintering these fractions has been studied by the DSC/TG method. The phase composition of sintering products has been studied and some of the physicochemical properties of the obtained samples have been determined.     

Stepwise extraction of brown coal from the Sergeevskoe deposit

The mechanism of the stepwise dissolution of coal was investigated. It was found that the step-by-step demineralization of extraction residues facilitated the quantitative extraction of bitumoids and their acid constituents. The acids were separated in accordance with bond types, and the individual composition of the resulting fractions was analyzed. It was established that more than a third of the organic matter of the test coal has aliphatic nature.     

Magnetic properties and microstructure of nanocrystalline soft magnetic Fe73.5−x Co x Cu1Nb3Si13.5B9 alloys

The influence of the annealing temperature, cooling rate, and magnetic field frequency in thermomagnetic treatment on the magnetic parameters of nanocrystalline Fe_73.5?x Co _x Cu₁Nb₃Si_13.5B₉ (x=0, 10, 20, and 30) alloys has been investigated. It has been revealed that a thermomagnetic treatment in a dc magnetic field of the nanocrystalline alloys containing cobalt leads to a shift of their hysteresis loop. With increasing Co content in the alloy, the shift of the hysteresis loop increases. This fact is, apparently, connected with the precipitation of α-Co and β-Co clusters and (Fe,Co)₃Si and (Fe,Co)₂B nanophases in which the magnetization direction is determined by the direction of the magnetic field during treatment.     

Phase composition of metamorphosed basalt and its sintering products

The phase composition of metamorphosed basalt from the Myandukha occurrence, Arkhangelsk oblast, has been determined by X-ray diffraction. Using differential scanning calorimetry and thermogravimetry data, we examined the effect of phase composition and particle size on the thermal behavior of ground basalt. The phase composition of the sintering products of the magnetic and nonmagnetic components of the basalt has been investigated.     

Inner-sphere condensation of EtNCO and MeCN through coinsertion into the Re-Cl bond

Reactions of rhenium pentachloride with ethyl isocyanate in dichloroethane and acetonitrile are the first to demonstrate the feasibility of inserting organic isocyanates and nitriles into a rhenium-halogen bond. IR spectroscopy and elemental analysis data show that the addition of one to three ethyl isocyanate molecules in dichloroethane yields ReCl₄[N(Et)C(O) _n ]Cl with n = 1−3, depending on the relationship between the reactants. The reaction in acetonitrile yields a heteromolecular insertion product containing a chain of two isocyanate groups and one nitrile group attached to the same rhenium-chlorine bond: ReCl₄[{N(Et)C(O)}₂N=C(Me)Cl]. When EtNCS is used instead of EtNCO, the reaction is reversible.