Tribotechnical Properties of Sintered Antifriction Aluminum-Based Composite under Dry Friction against Steel

The disadvantage of antifriction Al–Sn alloys with high tin content is their low bearing capacity. To improve this property, the aluminum matrix of the alloys was alloyed with zinc. The powder of Al–10Zn alloy was blended with the powder of pure tin in the proportion of 40/60 (wt.%). The resulting mixture of the powders was compacted in briquettes and sintered in a vacuum furnace. The sintered briquettes were subjected to subsequent pressing in the closed press mold at an elevated temperature. After this processing, the yield strength of the sintered (Al–10Zn)–40Sn composite was 1.6 times higher than that of the two-phase Al–40Sn one. The tribological tests of the composites were carried out according to the pin-on-disk scheme without lubrication at pressures of 1–5 MPa. It was established that the (Al–10Zn)–40Sn composite has higher wear resistance compared with the Al–40Sn one. However, this advantage becomes insignificant with an increase in the pressure. It was found that the main wear mechanism of the investigated composites under the dry friction process is a delamination of their highly deformed matrix grains.

STUDY OF THE STRUCTURE AND PROPERTIES OF LEAD-FREE RAPIDLY SOLIDIFIED ZINC-BASED ALLOYS DURING A HEAT TREATMENT

Представлены результаты исследований влияния сверхвысоких скоростей охлаждения расплава, равных не менее 10К/с, на свойства быстрозатвердевших сплавов системы Zn - Sn. Верхняя область фольги, контактирующая с кристаллизатором в процессе затвердевания, имела дисперсные частицы второй фазы, и по мере удаления от верхних слоёв размеры частиц укрупнялись. При комнатной температуре протекает распад пересыщенного твёрдого раствора с выделением дисперсных частиц. Дополнительная термическая обработка приводит к укрупнению частиц второй фазы, и способствует снижению микротвёрдости. Быстрозатвердевшие фольги с максимальной концентрацией цинка характеризуются наличием текстуры (0001), которая по мере увеличения содержания олова в цинке ослабляется, и при легировании выше 20 мас. % Sn происходит перестройка на текстуру (101̅0). Термическая обработка до 160 °С не приводит к изменению текстуры. The results of studies of the effect of ultrahigh melt cooling rates, equal to at least 10 K/s, on the properties of rapidly solidified alloys of the Zn - Sn system are presented. The upper region of the foil, in contact with the crystallizer during solidification, had more dispersed particles of the second phase, and as the distance from the upper layers increased, the particle sizes increased. At room temperature, the decomposition of a supersaturated solid solution proceeds with the release of dispersed particles. Additional heat treatment leads to the coarsening of the particles of the second phase, and helps to reduce the microhardness. Rapidly solidified foils with a maximum zinc concentration are characterized by the presence of a (0001) texture, which weakens as the tin content in zinc increases, and upon alloying up to 30 wt. % Sn is rearranged to (101̅0) texture. Heat treatment up to 160 °C does not change the texture.

The Effect of Tin Content on the Strength of a Carbon Fiber/Al-Sn-Matrix Composite Wire

The effect of tin content in an Al-Sn alloy in the range from 0 to 100 at.% on its mechanical properties was studied. An increase in the tin content leads to a monotonic decrease in the microhardness and conditional yield stress of the Al-Sn alloy from 305 to 63 MPa and from 32 to 5 MPa, respectively. In addition, Young’s modulus and the shear modulus of the Al-Sn alloy decreases from 65 to 52 GPa and from 24 to 20 GPa, respectively. The effect of tin content in the Al-Sn matrix alloy in the range from 0 to 50 at.% on the strength of a carbon fiber/aluminum-tin-matrix (CF/Al-Sn) composite wire subject to three-point bending was also investigated. Increasing tin content up to 50 at.% leads to a linear increase in the composite wire strength from 1450 to 2365 MPa, which is due to an increase in the effective fiber strength from 65 to 89 at.%. The addition of tin up to 50 at.% to the matrix alloy leads to the formation of weak boundaries between the matrix and the fiber. An increase in the composite wire strength is accompanied by an increase in the average length of the fibers pulled out at the fracture surface. A qualitative model of the relationship between the above parameters is proposed.

Material based on multilayer periodic structures with GeSiSn pseudomorphic layers

The growth of multilayer structures with Ge0.3Si0.7-yGey/Si heterojunction at tin content from 0 to 18% was studied. The X-ray diffractometry method shows the presence of strict periodicity of layers and a high level of tin content. It has been established that GeSiSn compounds are thermally stable in the annealing temperature range of 300-550 °C. A photoluminescence signal in the infrared range of about 3 microns is observed from a structure with pseudomorphic GeSiSn layers.

WIELAND B31

Wieland B31 (CuSn2Fe0.1P) is a copper-tin-iron-phosphorus alloy (tin bronze) with coherent precipitates. The lower tin content with small amounts of iron and phosphorus results in an electrical conductivity of at least 30% IACS. Precipitates of iron and phosphorus stabilize the structure, increase the strength, and improve the softening characteristics. Wieland B31 possesses the right combination of formability, conductivity, strength, and stress relaxation resistance to be used for automotive applications at relatively high ambient temperatures. In addition, its strength is similar to that of a 4% tin bronze. This datasheet provides information on composition, physical properties, elasticity, and tensile properties. It also includes information on corrosion resistance as well as forming and heat treating. Filing Code: Cu-926. Producer or source: Wieland-Werke AG.

The Chemical Composition of the Medieval Mirrors from Golden Horde Time Settlements

Introduction. The paper discussed the results of the study concerning the chemical composition of 16 mirrors from the Golden Horde period originating from the settlements Selitrennoe, Vodyanskoe, Uvekskoe Khmelevskoe I, Shirokiy Buerak and stored in the State Historical Museum (Moscow) and Saratov Regional Museum of Local Lore (Saratov). Method. The visual inspection of the items was carried out using the traceology method, XRF and SEM/EDS were used as a method of determining the elemental composition. To compare the results, data on the chemical composition of mirrors originating from other medieval sites in Eastern Europe were used. Analysis and Results. All but one mirror, made with a stone casting mold, were cast using the impression method. Some of the mirrors show traces of post-casting processing. Several types of alloys have been identified. Most of the mirrors were made of tin-lead bronze (7 items) with an increased (more than 20 %) tin content, which correlates with the results obtained on samples from other settlements of the pre-Horde and Horde times. Other large groups are mirrors made from multicomponent (3 items) and tin bronze (4 items). One mirror each is made of tin brass and lead bronze with the addition of arsenic. Mirrors with arsenic in their composition are also known from other samples from a nomadic cemetery of the Golden Horde period and settlement monuments, which indicates a sufficiently active existence of a more archaic metal in the 14th century.

The Recovery of Metallic Tin from an Industrial Tin-Bearing By-Product Containing Na2SO4 by Reduction Smelting Process

Tin was recovered in metal from an industrial tin-bearing byproduct containing Na2SO4 by carbothermic reduction smelting, and the effects of basicity (Na2O/SiO2), temperature, and reaction time on the recovery of tin were studied. Na2SO4 was reduced by carbon and formed into sodium silicate slag (Na2O–SiO2) in the presence of SiO2. Tin content in slag decreased with the increase of Na2O/SiO2 ratio in slag, temperature, and reaction time, but the recovery of tin was affected by volatilization of tin in high temperature and high silica region of basicity. In this study, the maximum recovery rate of tin was 94.8% at the experimental condition of 1200 °C, 2 h, and 0.55 of Na2O/SiO2 ratio. The major impurities in produced metal were Bi, Pb, Cu, Fe, and most of Bi, Pb, Cu were distributed to the metal phase, but the distribution of Fe was closely related to basicity.

Influence of Duty Cycle and Pulse Frequency on Structures and Performances of Electrodeposited Ni-W/TiN Nanocomposites on Oil-Gas X52 Steels

This paper describes the pulse current electrodeposition (PCE) mediated preparation of Ni-W/TiN nanocomposites. Pulse current electrodeposition (PCE) was used to make Ni-W/TiN nanocomposites. The nanoindentation, wear, and corrosion of deposited Ni-W/TiN nanocomposites were studied using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The influence of pulse frequency (PF) and duty ratio on the shape, structure, phase structure, wear, and corrosion resistance of Ni-W/TiN nanocomposites was studied. When the duty cycle (DC) was 10%, the results demonstrated that a considerable number of fine grains were present on the deposited Ni-W/TiN nanocomposites, forming smooth, uniform, and fine organization. Increasing DC decreased the content of TiN nanoparticles in Ni-W/TiN nanocomposites. The content of TiN nanoparticles reduced from 11.3 wt % to 7.3 wt % by increasing the DC from 10% to 50%. In contrast, as the PF was increased, the TiN content in Ni-W/TiN nanocomposites increased. When the PF was increased from 50 Hz to 150 Hz, the TiN content increased from 6.4 wt % to 9.6 wt %, respectively. Furthermore, with a PF of 150 Hz and a DC of 10%, the produced Ni-W/TiN nanocomposites had an average hardness of 934.3 HV with ~39.8 µm of an average thickness. The weight loss of the Ni-W/TiN nanocomposites was just 17.2 mg at a PF of 150 Hz, demonstrating the excellent wear resistance potential. Meanwhile, the greatest impedance was found in Ni-W/TiN nanocomposites made with a DC of 10% and a PF of 150 Hz, indicating the best corrosion resistance.

Micro-Stratigraphical Investigation on Corrosion Layers in Ancient Bronze Artefacts of Urartian Period by Scanning Electron Microscopy, Energy-Dispersive Spectrometry, and Optical Microscopy

The results of the analysis on some fragments of bronze belts and a bowl discovered from southwestern Armenia at the Yegheghnadzor archaeological site are discussed. The samples are dated to the 7–6th millennium BCE from the Urartian period. The artefacts were corroded, and a multilayer structure was formed. To study the stratigraphy of layers and their composition, the samples have been analyzed using SEM-EDS (Scanning Electron Microscopy, Energy-Dispersive Spectrometry) and OM (Optical Microscopy) techniques. The bronze finds appear with the typical incrustations rich in alloy alteration compounds. Concentrations of copper and tin in the alloys were quantified by SEM-EDS: the pattern and the percentage of the alloy are the same for the belts. Regarding the bowl sample, it is constituted by two foils perfectly in contact but different in color, thickness, and composition. The results evidenced that only two elements participate in forming the alloy composition in the samples: Cu and Sn. The tin content is variable from 7.75% to 13.56%. Other elements such as Ag, As, Fe, Ni, P, Pb, Sb, and Zn make up less than 1% and can be considered as impurities.

Phase Composition and Its Spatial Distribution in Antique Copper Coins: Neutron Tomography and Diffraction Studies

The chemical and elementary composition, internal arrangement, and spatial distribution of the components of ancient Greek copper coins were studied using XRF analysis, neutron diffraction and neutron tomography methods. The studied coins are interesting from a historical and cultural point of view, as they are “Charon’s obol’s”. These coins were discovered at the location of an ancient Greek settlement during archaeological excavations on the “Volna-1” necropolis in Krasnodar Region, Russian Federation. It was determined that the coins are mainly made of a bronze alloy, a tin content that falls in the range of 1.1(2)–7.9(3) wt.%. All coins are highly degraded; corrosion and patina areas occupy volumes from ~27 % to ~62 % of the original coin volumes. The neutron tomography method not only provided 3D data of the spatial distribution of the bronze alloy and the patina with corrosion contamination inside coin volumes, but also restored the minting pattern of several studied coins. Taking into account the obtained results, the origin and use of these coins in the light of historical and economic processes of the Bosporan Kingdom are discussed.