Adsorption of rhenium(VII) on 4-amino-1,2,4-triazole resin

The adsorption properties of 4-amino-1,2,4-triazole resin (4-ATR) for Re(VII) were investigated by static and dynamic adsorption–desorption measurements with ultraviolet–visible spectroscopy. The influence of conditions such as temperature, initial solution pH and contact time on the adsorption curve was studied. It was found that the 4-amino-1,2,4-triazole resin was suitable for adsorption of Re(VII). The saturated adsorption capacity was 354 mg·g^− 1resin at pH 2.6 in HAc–NaAc medium at 298 K. The adsorption rate constant was k₂₉₈ = 8.2 × 10^− 5 s^− 1. The adsorption behavior of 4-ATR for Re(VII) obeyed the Freundlich empirical equation; whilst changes in adsorption with temperature gave an enthalpy change ΔH  = − 11.8 kJ·mol^− 1. The molar ratio of the functional group of 4-ATR to Re(VII) was about 2:1. Re(VII) adsorbed on 4-ATR was eluted by 1.0 ~ 5.0 mol·L^− 1 HCl with 100% quantitative elution in 4.0 mol·L^− 1 HCl solution. The resin can be regenerated and reused without apparent decrease in adsorption capacity.     

Adsorption behavior of Cd(II) from aqueous solutions onto gel-type weak acid resin

The adsorption and desorption behaviors of Cd(II) on gel-type weak acid resin (GTWAR) have been investigated. The influence of operational conditions such as contact time, initial concentration of Cd(II), initial pH of solution and temperature on the adsorption of Cd(II) has also been examined. The results show that the optimal adsorption condition of GTWAR for Cd(II) is achieved at pH = 5.95 in HAc–NaAc medium. The maximum uptake capacity of Cd(II) is 282 mg/g GTWAR at 298 K. The adsorption of Cd(II) follows the Langmuir isotherm and Freundlich isotherm, and the correlation coefficients have been evaluated. Even kinetics on the adsorption of Cd(II) has been studied. The apparent activation energy E_a and adsorption rate constant k₂₉₈ values are 2.95 kJ/mol and 3.02 × 10^− 5 s^− 1, respectively. The calculation data of thermodynamic parameters which ΔS value of 110 J/(mol K) and ΔH value of 13.1 kJ/mol indicate the endothermic nature of the adsorption process. Whilst, a decrease of Gibb's free energy (ΔG) with increasing temperature indicates the spontaneous nature of the adsorption process. Finally, Cd(II) can be eluted by using 0.5 mol/L HCl solution and the gel-type weak acid resin can be regenerated and reused. The sample was described by IR spectroscopy and scanning electron micrographs (SEM).     

Properties of electrolyte solutions relevant to high concentration chloride leaching. II. Density, viscosity and heat capacity of mixed aqueous solutions of magnesium chloride and nickel chloride measured to 90 °C

Results of density and viscosity measurements for aqueous solutions of MgCl₂ (0.5–3.5 mol L^− 1) and MgCl₂ + 10% NiCl₂ (0.5–3.5 mol L^− 1) at temperatures of 25, 60 and 90 °C show an almost linear increase in density with total concentration, while low nickel contents and temperature have comparatively small effects. Viscosities of MgCl₂ solutions rise sharply at 25 °C but are significantly lower at 90 °C. The viscosity of 3–4 mol kg^− 1 MgCl₂ at 90 °C is similar to water at 25 °C. Nickel has no significant effect on the viscosity of these solutions.Results of heat capacity measurements for aqueous solutions of MgCl₂ (0.5–3.5 mol L^− 1) and MgCl₂ + 10% NiCl₂ (0.5–3.5 mol L^− 1) at temperatures of 60 and 90 °C show that the heat capacities of these solution decrease significantly with total concentration, while the effects of low nickel contents and temperature are again comparatively small.     

Extraction of Fe(III) from hydrochloric acid solutions using Amberlite XAD-7 resin impregnated with trioctylphosphine oxide (Cyanex 921)

Ferric ions were efficiently removed from HCl solutions using Amberlite XAD-7 resin impregnated with trioctylphosphine oxide (Cyanex 921). Iron was removed under the form HFeCl₄ through direct binding on the resin or by extraction with Cyanex 921 involving a solvation mechanism. High concentrations of HCl and intermediary extractant loadings were required for maximum sorption efficiency and rationale use of the extractant. At intermediary extractant loading (in the range 300–450 mg Cyanex 921 g^− 1) the maximum sorption capacity increased with extractant loading. Maximum sorption capacity slightly increased with temperature, the reaction is endothermic and the enthalpy change was found close to − 30.8 kJ mol^− 1. Sorption isotherms were fitted with the Langmuir equation and maximum sorption capacity reached values as high as 20–22 mg Fe g^− 1 in 3 M HCl solutions. Despite the good fit of experimental data with the pseudo second-order rate equation, sorption kinetics was controlled by the resistance to intraparticle diffusion. The intraparticle diffusion coefficient (D_e) varying in the range 1.2 × 10^− 11–4.7 × 10^− 10 m² min^− 1 was found to increase with metal concentration and with temperature, while varying the extractant loading it reached a maximum at a loading close to 453 mg Cyanex 921 g^− 1. The desorption of Fe(III) can be achieved using 0.1 M solutions of nitric acid, sulfuric acid, sodium sulfate and even water, maintaining high efficiencies for sorption and desorption for at least 5 cycles.     

Adsorption behavior of rare earth elements using polyethyleneglycol (phosphomolybdate and tungstate) heteropolyacid sorbents in nitric solution

A new type of crystalline sorbent was prepared by the reaction of polyethyleneglycol (PEG) with phosphomolybdic (PMo) and phosphotungstic (PW) heteropolyacids. The morphology of the obtained sorbents was studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM). It has been shown that a complexing reaction occurs between PEG and the heteropolyacids. By using these sorbents, the adsorption behaviors of rare earth elements in nitric solution were studied. The effects of temperature, contact time, nitric acid and initial metal ion concentration on the adsorption were investigated. In 0.1–5.0 mol L^− 1HNO₃, the adsorption percentage decreases with the increase of acid concentration. H,PEG400,PW and H,PEG400,PMo exhibited a different selectivity for rare earth metals, with H,PEG400,PW adsorbing in the order of La³⁺ > Y³⁺ > Pr³⁺ > Gd³⁺ > Sm³⁺, and H,PEG400,PMo in the order of Y³⁺ > La³⁺ > Pr³⁺ > Gd³⁺ > Sm³⁺. The experimental maximum adsorption capacities of the sorbents are in the range of 90–225 mg g^− 1 for Y³⁺, La³⁺, Pr³⁺, Sm³⁺ and Gd³⁺. In all cases, the maximum adsorption capacities of H,PEG400,PW are near to those of H,PEG400,PMo. The equilibrium data were evaluated according to the Freundlich and Langmuir isotherms and the Langmuir equation gave a better fit and modeled the adsorption well.     

Arsenic removal from copper ores and concentrates through alkaline leaching in NaHS media

Removal of arsenic impurity in ores and concentrates containing copper (Cu) through alkaline leaching in NaHS media was investigated in this work. Samples containing Cu from 10 to 40 wt.% and arsenic from 0.8 to 14 wt.% with enargite (Cu₃AsS₄) as main arsenic bearing mineral were used as starting materials and all leaching tests were conducted at 80 °C under normal atmospheric pressure. Solution and/or slurry potential and pH were maintained consistently below − 500 mV (SHE) and above 12.5 respectively with the addition of NaHS and NaOH, creating a reducing environment for arsenic dissolution and conversion of Cu₃AsS₄ to Cu₂S. Pulp density ranged from 100 to 1000 g/L, NaHS and NaOH reagents were added at 50–200 g/L each and leaching time varied from 10 min to 10 h.Characterization of solid samples (original and leach residue) by XRD and XRF analyses and chemical analysis of both solid and solution samples by ICP analysis showed that Cu₃AsS₄ in the starting material was completely decomposed or transformed to Cu₂S and arsenic released into solution as As (III)/As³⁺ ions (Na₃AsS₃). Over 90% of arsenic in the starting materials was removed within 1–3 h for materials with arsenic content from 1 to 4 wt.% and within 3–6 h for materials with arsenic content over 4–10 wt.%. Dissolution and analysis of leach residues obtained after leaching by ICP indicated that arsenic in the starting materials has been reduced in all cases to below 0.5 wt.%. In all test conditions dissolution of Cu and Fe into solution was not detected, indicating selective leaching of arsenic. NaHS application for removal of arsenic in Cu-ores and/or concentrates was demonstrated in this work and further research is in progress to develop a process to include treatment of arsenic leached into solution.     

Ionic conduction in BaxCe0.8Pr0.2O3-

[1]Iwahara H,Yajima T,Ushida H.Effect of ionic radii of dopants on mixed ionic conductions (H++O2) in BaCeO3-based electrolytes.SolidState Ionics,1994,70/71:267. [2]Taniguchi N,Yasumoto E,Nakagiri Y,Gamo T.Sensing properties of an oxygen sensor using BaCe0.8Gd0.2O3-a ceram-ics as electrolytes.J.Electrochem.Soc.,1998,145(5):1744. [3]de Arcllano-Lopez A R,Goretta K C,Park E T,Dorris S E,Balchandran U,Routbort J L.High-temperature deformation of a BaCe0.8Y0.2O3-y+Ni composite.J.Fur.Ceram.Soc.,2002,22:2555. [4]Ma G L,Shimura T,Iwahara H.Ionic conduction and non-stoichiometry in BaxCe0.90Y0.10O3-a.Solid State lonics,1998,110:103. [5]Ma G L,Matsumoto H,Iwahara H.Ionic conduction and non-stoichiometry in non-doped BaxCeO3-a.Solid State Ionics,1999,122:237. [6]Ma Guilin,Qiu Ligan,Chen Rong.Performance of the solid oxide fuel cell based on BaxCe0.8Sm0.2O3-a.Acta Chimica Sinica (in Chin.),2002,60(12):2135. [7]Ma G L,Qiu L G,Tao W H,Zhou L,Chen R.Ionic conduc-tion in BaxCe0.8Sm0.2O3-a solid electrolyte.J.Chin.Rare Earths Soc.(in Chin.),2003,21(2):236. [8]Qiu L G,Ma G L,Wen D J.Study on preparation and electri-cal properties of Ba1.03Ce0.8Eu0.2O3-a solid electrolyte.J.Rare Earths,2004,22(5):678. [9]Qiu L G,Ma G L,Wen D J.Ionic conduction in BaxCe0.8Er0.2O3-a.Solid State lonics,2004,166:69. [10]Wang M Y,Qin L G.Mixed conduction in BaCe0.8Pr0.2O3-a ceramic.Chin.J.Chem.Phys.,2008,21:286. [11]Bonanos N.Transport properties and conduction mechanism in high-temperature protonic conductots.Solid State Ionics,1992,53-56:967. [12]Ma G L,Shimura T,Iwahara H.Simultaneous doping with La3+ and y3+ for Ba2+-and Ce4+-sites in BaCeO3 and the ionic conduction.Solid State Ionics,1999,120:51. [13]Shima D,Halle S M.The influence of cation non-stoichiome-try on the properties of undoped and gadolinia-doped barium ceres.Solid State Ionics,1997,97:443.     

Properties of electrolyte solutions relevant to high concentration chloride leaching. III. Solubility of pertinent solids and iron(III)/iron(II) redox potential measured in concentrated magnesium chloride solutions

Results of solubility measurements of nickel chloride, manganese chloride, iron(II) chloride, hematite and akaganeite in aqueous solutions of MgCl₂ (0.5–3.5 mol L^− 1) at temperatures of 60 and 90 °C are reported. Solubilities of metal(II) chlorides decrease almost linearly with MgCl₂ concentration due to the common ion effect. Nickel chloride and iron(II) chloride solubilities are very similar, while manganese chloride is about 30% more soluble.Hematite is more stable (i.e. less soluble) than akaganeite under all conditions investigated in this study, while ferrihydrite is considerably less stable. In other words, there is no change in the relative stabilities of these phases effected by the presence of high magnesium chloride concentrations. The solubility of all of these phases decreases with temperature and, for each temperature, the solubility constants increase linearly with the MgCl₂ concentration. The present results allow the prediction of the iron concentration as a function of the H⁺ and MgCl₂ molality at equilibrium with hematite or akaganeite.The Fe(III)/Fe(II) redox behaviour has been characterized in concentrated aqueous solutions of MgCl₂ (1.5–3.5 mol L^− 1) at a temperature of 25 °C. Standard redox potentials are ca. 100 mV lower than at infinite dilution and change linearly by only 13 mV in the range 2–4 mol L^− 1 MgCl₂.     

Properties of electrolyte solutions relevant to high concentration chloride leaching I. Mixed aqueous solutions of hydrochloric acid and magnesium chloride

A computer code based on a Pitzer model has been developed for the comprehensive prediction of the thermodynamic properties of MgCl₂–HCl aqueous solutions over a wide range of conditions from 25 to 120 °C and from 0–350 g L^− 1 chloride. This code was applied to the calculation of (i) water activities and mean ionic activity coefficients for mixed aqueous solutions of hydrochloric acid and magnesium chloride over a wide range of concentrations and to 100 °C, (ii) solubilities of MgCl₂·6H₂O in MgCl₂–HCl solutions to 80 °C, (iii) partial pressures of HCl(g) and H₂O(g) over MgCl₂–HCl aqueous solutions at various temperatures and (iv) partial pressures of HCl(g) at the normal boiling point of these mixed electrolyte solutions. The model predictions are in excellent agreement with available experimental data and confirm evidence from the literature that MgCl₂(aq) and HCl(aq) mix almost ideally at constant water activity.     

Laser chemical production of thin iron films,powders, and fibers from the carbonyl gaseous phase

Conclusions Healing a quartz substrate in a medium of IPC to a temperature above 500 K. by pulsed (> 5·10^–1 sec) radiation of a CO₂ laser with intensity of 50–100 W·cm^–2 yields thin (up to 3 m) iron films at a rate of 2 m·sec^–1 on a surface bounded by the cross section of the laser beam.When the intensity of the radiation is increased to 250 W·cm^–2, the process of decomposition of the IPC spreads to the gaseous phase. Together with intense crystallization of iron on the surface of the substrate (the surface temperature is 1500 K) a finely disperse (0.1–0.3 m) iron powder also forms.Translated from Poroshkovaya Metallurgiya, No. 1(325), pp. 85–89, January, 1990.     

Preparation and thermoelectric properties of ternary rare earth sulfide γ-Ce3–xEuxS4

The effect of Eu-substitution on the density and thermoelectric properties of ternary sulfide Ce_3–xEu_xS₄ (0≤x≤0.8) compacts was investigated. Ce_3–xEu_xS₄ powders were prepared via the sulfurization of the oxide using CS₂ gas at 1473 K. The pressureless sintered Ce_3–xEu_xS₄ compacts in the atmosphere were crystallized in the γ-phase. The density of the Ce_3–xEu_xS₄ compacts increased with the increasing of Eu-substitution. Eu-substitution yielded a higher Seebeck coefficient and lower electrical resistivity. The highest value of the thermoelectric power factor of 1.41×10⁻⁴ W/K²m was obtained for the Ce_2.2Eu_0.8S₄ compact at 673 K. It indicated that Eu-substitution was effective for improving thermoelectric properties of Ce_3–xEu_xS₄.     

Examination of the physical properties of ZrC-W carbide-metallic alloys

Conclusions The heat conductivity of the two-phase alloys of ZrC-W system increases with an increase of the tungsten content and with increase in temperature. This is caused by the electron contribution to the heat conductivity of the crbide phase.The electrical resistance of these alloys decreases with increase in tungsten content and increases with increase in temperature. At a mass constant of ZrC > 25% the temperature dependence of the electrical resistance of the alloys is nonlinear as a result of slight overlapping of the valency band by the conduction band in the carbide phase.The mean coefficient of thermal expansion ZrC-75% (wt.) W alloy increases with increase in temperature from 5.5·10^–6 in the range 300–600 to 7.05·10^–6 K^–1 in the range 300–2300°K.The spectral emission factor =0.65 mm of the ZrC-W alloys increases with an increase of the zirconium carbide content. With increase in temperature decreases for tungsten, zirconium alloy, and alloys with a mass content of W < 40%. For the alloys with a tungsten content of 45–75% depends only slightly on temperature. This can be explained by the presence of tungsten carbides in the subsurface layer. The critical wavelength of these carbides (_X=500–600 nm) is close to the wavelength in pyrometric measurements.The fracture tensile stress of the specimens of the alloys with a mass constant of tungsten of 75% increases with increase in temperature as a result of utilization of a certain ductility margin of the brittle material.Translated from Poroshkovaya Metallurgiya, No. 6(330), pp. 93–100, June, 1990.     

Effect of phosphate on lead removal during a copper recycling process from wastes using ammoniacal chloride solution

Techniques for the removal of lead have been studied in order to develop a hydrometallurgical copper recycling process consisting of copper leaching from wastes using an ammoniacal chloride solution and subsequent copper electrowinning. The solubility of Pb(II) in the ammoniacal chloride solution increased with ammonia concentration; this was attributable to the formation of a lead ammine complex. The lead dissolution was depressed from the order of 10^− 3 M to the order or 10^− 5 M by the addition of phosphate into the leaching solution because of the precipitation of chloropyromorphite (Pb₅(PO₄)₃Cl), while no significant effect was observed by the addition of carbonate. Linear sweep voltammetry and potentiostatic electrolysis in the solution containing Pb(II) revealed that lead was deposited during the copper electrowinning, even in the potential region more positive than the equilibrium redox potential for the Pb/Pb(II) couple on the lead electrode, because of the alloy formation with copper. In a galvanostatic electrolysis, however, the lead content at the electrodeposited copper cathode was found to be lower than 5 ppm at the current density range of 125–400 A/m², when the Pb(II) concentration in the electrolyte was 5 × 10^− 5 M. Since this Pb(II) concentration was achieved by the phosphate addition, these results indicated the effectiveness of phosphate for lead removal in the copper recycling process using the ammoniacal chloride solution.     

Effect of surface-active agents on the properties of a copper powder produced by the autoclave method

Conclusions Carboxyl-containing water-soluble polymers have the strongest influence on the properties of copper powders and are the most effective in reducing their deposits on the inside reactor surface. The optimum SAA consumption rate is 0.003–0.007 g per 1 g of copper. Higher consumption rates intensify the flocculatton of powder particles and increase the carbon content of the powder, which is undesirable, since it makes the latter's subsequent processing more difficult. The carboxyl-containing substances currently produced by industry can be used as SAAs, but, because of their low carboxyl-group content (not more than 45–60%), powders produced in their presence become fairly severely contaminated with carbon owing to destruction of inert radicals. By suitable choice of type of carboxyl-containing SAA it is possible to vary the properties of powders in the following ranges: specific surface 0.02–0.18 m²/g, apparent density 0.9–2.9 g/cm³, mean particle size 20–42m, and flowability 0–2.6 g/sec.Translated from Poroshkovaya Metallurgiya, No. 7(283), pp. 5–8, July, 1986.     

Reaction of Tungsten with Liquid Co ― Sn Alloys

The solubility of tungsten in Co Sn melts and the growth kinetics of a W₆Co₇ phase layer at the tungsten melt interface were studied at 1200°C. The liquid alloys composition in the three-phase equilibrium W W₆Co₇ melt was established as (at. fraction) 0.51 Co, 0.49 Sn, 2.3·10^–3 W. The solubility of tungsten in the investigated range of melt compositions is well represented by the equation lgx _W = –0.964-3.420x _Sn, where x _W and x _Sn are atomic fractions of the elements in the melt. The calculated thermodynamic properties can be used for the analysis of other systems which include cobalt and tungsten.     

Effect of reduced graphene oxide-supported copper addition on electrochemical properties of La0.7Mg0.3Ni2.8Co0.5 electrodes

The reduced graphene oxide-supported copper(Cu@rGO) nanocomposite was introduced to improve the electrochemical properties of La_(0.7)Mg_(0.3)Ni_(2.8)Co_(0.5)alloy electrodes.Experimental results show that adding Cu@rGO nanocomposite with mass fractions of x wt%(x=0,3,6 and 9) to the alloy electrodes provides electrodes with maximum discharge capacities of 368.9 mAh/g(x=0),373.2 mAh/g(x=3),407.3 mAh/g(x=6) and 398.6 mAh/g(x=9),and high-rate dischargeabilities at a discharge current density of1200 mA/g of 40.5%(x=0),64.0%(x=3),82.0%(x=6) and 76.0%(x=9).The addition of Cu@rGO nanocomposite also provides alloy electrodes with hydrogen diffusion coefficients of 3.7×10~(-10) cm~2/s(x=0),4.1×10~(-10) cm~2/s(x=3),4.2×10~(-10) cm~2/s(x=6) and 4.0×10~(-10) cm~2/s(x=9).Clearly,the addition of 6 wt%Cu@rGO nanocomposite not only increases the electrochemical capacity of La_(0.7)Mg_(0.3)Ni_(2.8)Co_(0.5) alloy electrodes,but also improves their electrochemical kinetic properties.     

Mechanical properties of multilayer steel-copper composites

Conclusions The tensile strength _t and fatigue limit _–1 of powder metallurgical and cast MLCs grow with decreasing mean layer thickness h starting from 5000 Å. In cast Type 45 steel/copper composites high tensile strength _t (222 kgf/mm²) combines with high impact strengtha _n (8 kgf-m/cm²) and hardness (42–45 HRC). With powder metallurgical and cast MLCs, at any given life NG the cycle stress necessary for fatigue fracture grows with decreasing mean layer thickness (within the h = 5000-500 Å range investigated).Translated from Poroshkovaya Metallurgiya, No. 11(203), pp. 33–37, November, 1979.     

Leaching of chalcopyrite with ferric ion. Part IV: The role of redox potential in the presence of mesophilic and thermophilic bacteria

This paper reports a study on the effect of redox potential in chalcopyrite bioleaching in the presence of iron- and sulphur-oxidizing bacteria. Bioleaching tests were carried out in stirred Erlenmeyer flasks at 180 rpm, with 0.5 g of chalcopyrite mineral, 99 ml of a sulphate solution of Fe³⁺/Fe²⁺ (with the redox potential ranging between 300 and 600 mV Ag/AgCl) at pH 1.8 and 1 ml of a mesophilic (35 °C) or thermophilic (68 °C) culture. The overoxidation of the leaching solution, due to the activity of iron-oxidizing microorganisms (Acidithiobacillus ferrooxidans, Leptospirillum ferrooxidans and Sulfolobus BC), favoured the precipitation of jarosite on chalcopyrite surfaces followed by passivation. Iron- and sulphur-oxidizing microorganisms, such as A. ferrooxidans and Sulfolobus BC adapted for 4 months to elemental sulphur as the sole energy source, recovered their iron-oxidizing ability after being in contact with Fe²⁺.     

Effect of abrasive component concentration on the mechanical properties and structure of tool material prepared by electric discharge sintering

Conclusions It was experimentally established that for electric discharge sintering of copper-abrasive composites the increase of abrasive concentration to 100% (1 g/cm³) affects the process substantially, while further increase to 200% does not have much effect.For composites containing 100% (0–1 g/cm³) abrasive, the chief factor affecting the change in shock viscosity is the abrasive concentration, while the factor affecting the strength is the binder phase composition.Translated from Poroshkovaya Metallurgiya, No. 2(266), pp. 77–80, February, 1985.     

Deformation structure ofα-SiC single crystals

Conclusions The deformation of-SiC single crystals in bending with the direction of extension and compression approximately parallel to the basal face (the axis of bending parallel to (0001), T = 2000–2100°C) involves slip over the basal plane; the directions of slip are <11¯20> and <10¯10>. Accordingly, crystallographic planes rotate about parallel axes, <10¯10> and <11¯20>. Slip in the <10¯10> direction may be a consequence of migration of dislocations with Burgers vectors equal to b=2/3 <10¯10> (a full dislocation and <10¯10> (a partial dislocation). X-ray microdiffraction observations show [12] that partial dislocations with Burgers vector components parallel to [101¯1] frequently form in-SiC; travel of partial dislocations apparently plays an important part in the deformation of -SiC. The deformation of-SiC is accompanied by kink band formation [1].During the deformation process, dislocations pile up in slip planes, and their density increases by two to three orders; their distribution is very uneven, typical values of being 10⁸–10¹⁰ cm^–2 and values of _max of 10¹¹cm^–2 being recorded in zones with a large local curvature.Because of the changing specimen structure, two stages may be detected in the deformation process: 1) formation of elastically bent regions and 2) comminution (formation of microcracks within the specimen).The crystals investigated exhibited only micropolygonization, when the block size in the basal plane was 30 and the block disorientation 10. Neither postdeformation annealing for 10–30 h at 2000–2100°C nor prolonged (4–8 h) holding of specimens under load produced any macroscopic polygonization. The structure of naturally deformed specimens, too, was found to contain no polygonization macroblocks. It would appear that, because of the appreciable activation energy for diffusion and strong covalent linkage in-SiC, dislocations cannot readily climb over large (>10) distances in this compound; in this connection, the relaxation properties of-SiC would be expected to be weak.The methods of investigation employed in our work are comparatively simple to use. They do not give any information about elementary deformation acts, but throw a light on the character of lattice variation in various volumes (V ranging from 0.1t to 6.0t mm³, where t=200–500 is the crystal thickness) and are particularly useful in topographic x-ray photography when there is no contrast on individual linear defects in crystals.Translated from Poroshkovaya Metallurgiya, No. 8 (128), pp. 63–72, August, 1973.