scholarly journals Temporal pattern of the mechanoluminescent lighting from impact-loaded ZnS ceramics

2020 ◽  
Vol 38 (2) ◽  
pp. 279-282
Author(s):  
Alexandre Chmel ◽  
Anatolij Dunaev ◽  
Igor Shcherbakov
Keyword(s):  
Plastic Deformation ◽  
Temporal Pattern ◽  
Physical And Mechanical Properties ◽  
Interatomic Bond ◽  
Ductile Materials ◽  
Bond Breakage ◽  
Brittle Solids ◽  
Two Peaks ◽  
The Given ◽  
Technological Methods

AbstractMechanoluminescence (ML) from deformed ductile materials is caused by sliding of charged dislocations. The main source of the ML in loaded brittle solids is the interatomic bond breakage. In this work, the ML from impact damaged ductile ZnS ceramics was studied. It was revealed that the time series of ML pulses exhibited two well-separated peaks. A two-stage ML excitation of this kind in ZnS ceramics was observed when the applied load exceeded an ultimate plastic deformation. The positions of each peak along the time axis were found to be dependent in different ways on physical and mechanical properties of crystallites that constituted the given ceramics. The investigated ceramics were produced by four different technological methods. The obtained samples differing in the dimensions of grains and separation of grain boundaries were tested. The statistical analysis of a temporal pattern of the ML lighting showed that the mechanisms of excitation of the two peaks were not the same. The first ML peak was assigned to the plastic deformation preceding the ceramics cracking. The second peak originated from the interatomic bond breakage in nucleated and growing cracks.

MANUFACTURE INVESTIGATION OF CARTRIDGE WITH BOTTOM-MOST PART FLANGE BY DIRECT EXTRUSION WITH COUNTERPUNCH. REPORT 13. DETERMINATION OF DEFORMED STATE UNDER STRAITENED EXTRUSION IN FOURTH CENTRAL AREA OF PLASTIC DEFORMATION

2020 ◽  
Vol 0 (4) ◽  
pp. 43-51
Author(s):  
A. L. Vorontsov ◽  
◽  
I. A. Nikiforov ◽  
Keyword(s):  
Plastic Deformation ◽  
Plastic Flow ◽  
Central Area ◽  
Direct Extrusion ◽  
Deformed State ◽  
Cumulative Deformation ◽  
The Given ◽  
General Method

Formulae have been obtained that are necessary to calculate cumulative deformation in the process of straitened extrusion in the central area closed to the working end of the counterpunch. The general method of plastic flow proposed by A. L. Vorontsov was used. The obtained formulae allow one to determine the deformed state of a billet in any point of the given area. The formulae should be used to take into account the strengthening of the extruded material.

Thermal Decomposition of Vulcanized Structures of Deformed Vulcanizates Containing Various Accelerators

1953 ◽  
Vol 26 (4) ◽  
pp. 759-763 ◽  
Author(s):  
B. Dogadkin ◽  
Z. Tarasova
Keyword(s):  
Stress Relaxation ◽  
Physical And Mechanical Properties ◽  
Heat Stability ◽  
Chemical Bonds ◽  
Structural Elements ◽  
Specific Chemical ◽  
Vulcanized Rubber ◽  
Different Temperatures ◽  
Chemical Groups ◽  
The Given

Abstract According to the hypotheses developed by the authors, vulcanized rubber is a system in which the molecular chains are united by local molecular and chemical bonds of varying intensity. The concentration, distribution, and strength of these bonds determine the principal physical and mechanical properties of the vulcanizates. Consequently the study of the structure of the vulcanizate is of primary practical value. The explanation of the nature of the bonds in a vulcanizate by chemical methods is very difficult, mainly because of the impossibility of distinguishing the specific chemical groups which enter into the composition of the different molecular chains from those bonds between the chains which are responsible for the development of spatial structures. From this view point, the thermo-mechanical method described below, which is based on the study of stress relaxation at different temperatures, is of great significance. As was shown by Dogadkin and Reznikovskii˘, the delayed stress relaxation in a vulcanizate at temperatures up to 70° C is caused by rupture of the local intermolecular bonds and the regrouping of the structural elements of the polymeric chains without destruction of the chemical bonds between them. Accordingly, after some time at these temperatures, a practically balanced stress is established, which depends on the number of the stronger bonds remaining. At temperatures above 70° C, rupture of the chemical bonds between the chains takes place; its speed increases with decrease of the energy activating the rupture of the given type of bond. Particularly in the case of sulfur vulcanizates, we can assume that the following types of bonds exist between the chains of the rubber: (1) —C—C—, which develop as a result of the polymerizationprocesses; (2) —C—S—C— monosulfide; (3) —C—S—S—C— disulfide, and (4) —C—Sn—C— polysulfide, formed as a result of the direct participation of the vulcanizing agent, sulfur, in the process of joining of the molecular chains. The energy of these chains can be estimated as 62.7 kcal, per mole for C—C, 54.5 kcal. per mole for C—S, and 27.5 kcal. per mole for the —S—S bond. Naturally, the heat stability of a vulcanizate will depend on which of the indicated types of bonds predominates.

Intermetallics of Aluminum

2019 ◽  
Author(s):  
Georg Frommeyer ◽  
Sven Knippscheer
Keyword(s):  
Crystal Structure ◽  
Mechanical Properties ◽  
Plastic Deformation ◽  
High Temperature ◽  
Physical Properties ◽  
Intermetallic Compounds ◽  
Oxidation Behavior ◽  
Physical And Mechanical Properties ◽  
Structural Materials

Aluminum-rich intermetallic compounds of the Al3X-type with transmission metals (X = Ti. Zr, Nb, V) of Groups IVb and Vb are of interest in the development of novel high-temperature and lightweight structural materials. This article describes the important physical and mechanical properties of trialuminides with DO22 structure and their L12 variations. Topical coverage includes: crystal structure and selected physical properties, plastic deformation, oxidation behavior, and applications.

scholarly journals Distribution of the components of the building mixture in the presence of secondary raw materials during rotary mixing

2020 ◽  
Vol 220 ◽  
pp. 01060
Author(s):  
Anna Kapranova ◽  
Daria Bahaeva ◽  
Dmitry Stenko ◽  
Alexander Vatagin ◽  
Anton Lebedev ◽  
...  
Keyword(s):  
Raw Materials ◽  
Physical And Mechanical Properties ◽  
Distribution Functions ◽  
Stochastic Description ◽  
Rarefied Flows ◽  
Secondary Raw Materials ◽  
Characteristic Angle ◽  
Two Stages ◽  
The Given ◽  
Number Of Particles

The purpose of this study is a stochastic description of the distribution of solid dispersed components, including those from secondary raw materials, according to the characteristic angle of scattering ϴij when receiving a construction mixture at the first stage of operation of the rotary apparatus. Two stages of the formation of rarefied flows are assumed: when scattering particles of components by elastic blades of a rotating drum and when interacting with the baffle surface. Modeling method this is energy method of Klimontovich Yu.L. The analysis of the efficiency of the first stage (rotary mixing) is carried out based on the obtained distribution functions of the number of particles of bulk components over the scattering angle, taking into account their physical and mechanical properties and a variety of design and operating parameters of the apparatus. The bulk of the particles of the mixed components are scattered at the initial angles of rotation of the mixing drum, when the deformation of the elastic blades is most significant. This is accompanied by the characteristic first bursts of the obtained distribution curves (ϴij< 0.1 rad) for the number of particles of the tested bulk materials at the given ranges of parameters.

Study on Microstructure and Properties of Aged Cu-Ti-Zr-RE Alloy

2009 ◽  
Vol 79-82 ◽  
pp. 1687-1690
Author(s):  
Xing Min Cao ◽  
Yu Bin Zhu ◽  
Fuan Guo ◽  
Chao Jian Xiang
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Electrical Conductivity ◽  
Plastic Deformation ◽  
Tensile Strength ◽  
Physical And Mechanical Properties ◽  
Good Combination ◽  
Maximum Strength ◽  
Micro Hardness ◽  
Peak Aging

Electrical conductivity, tensile strength and micro-hardness of Cu-3.5wt.%Ti-0.1wt.%Zr-RE alloy were investigated after optimizing technics of plastic deformation and the heat treatment. The results show that good combination of the physical and mechanical properties, such as tensile strength 1160 MPa, micro-hardness 335 Hv and electrical conductivity 15 IACS% can be obtained on peak aging at 420°C for 7 h. Maximum strength was associated with the precipitation of metastable, ordered and coherent β/ (Cu4Ti) phase on peak aging. Then the strength decreased due to the precipitation of β (Cu3Ti) phase in alloys overaged.

Physical and Mechanical Properties of Mo5X3+α (X=Si, B, C) Single Crystals

2002 ◽  
Vol 753 ◽  
Author(s):  
Taisuke Hayashi ◽  
Kazuhiro Ito ◽  
Katsushi Tanaka ◽  
Masaharu Yamaguchi
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
Single Crystals ◽  
Plastic Anisotropy ◽  
Physical And Mechanical Properties ◽  
Structure Type ◽  
Advanced Materials ◽  
Anisotropy Ratio ◽  
Higher Temperature ◽  
Better Than

ABSTRACTMo5X3+α (X=Si, B, C) intermetallic compounds such as Mo5SiB2 (D8l), Mo5Si3 (D8m) and Mo5Si3C (D88) have a great potential for ultra-high temperature applications. The present study was undertaken putting greater emphasis on clarifying how their physical and mechanical properties are similar or different in terms of a structure type. Some interesting features are summarized in this paper.The resistivity of Mo5SiB2, Mo5Si3 and Mo5Si3C single crystals exhibited a negative curvature (d2ρ(T)/dT2<0), with a tendency towards saturation. In the Mo5Si3C with large ρ0 due to impurity carbon atoms, resistivity saturation is pronounced. In contrast, a much higher temperature is required to reach saturation in the Mo5SiB2. The anisotropy ratio of CTE (αc/αa) for the Mo5SiB2 is about 1.2–1.6 and is significantly reduced from about 2 of the Mo5Si3 and Mo5Si3C. On the other hand, the Young's modulus of the Mo5SiB2 is more anisotropic than those of the Mo5Si3 and Mo5Si3C. Plastic anisotropy was observed in the Mo5SiB2, because only slip on [001] {100} is operative at 1500°C. On the contrary, plastic deformation was observed at temperatures above 1300°C for the Mo5Si3C and Mo5Si3. Anisotropy of their plastic deformation was much less than that of the Mo5SiB2, presumably because more than two slip systems can be activated. Creep resistance of the Mo5SiB2 is much better than that of the Mo5Si3 as well as the most advanced materials such as MoSi2 and Si3N4 based structural ceramics.

Mechanical Properties of Ultrafine-Grained Al-Mg Alloy Produced by Severe Plastic Deformation

2017 ◽  
Vol 743 ◽  
pp. 203-206 ◽  
Author(s):  
Alexander A. Kozulin ◽  
Vladimir A. Krasnoveikin ◽  
Vladimir A. Skripnyak ◽  
Evgeny N. Moskvichev ◽  
Valery E. Rubtsov
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
High Efficiency ◽  
Physical And Mechanical Properties ◽  
Treatment Method ◽  
Mg Alloy ◽  
Complex Investigation ◽  
Angular Pressing ◽  
Ultrafine Grained

This study examines the effect of severe plastic deformation on the physical and mechanical properties of a light structural Al-Mg alloy. Severe plastic deformation has been performed by equal channel angular pressing through a die with an angle of 90° between the channels to produce ultrafine-grained structure in specimens of studied alloy. A complex investigation of the physical and mechanical properties of the processed alloy has been carried out to examine the microstructure and texture, and to measure microhardness, yield stress and ultimate tensile strength. The obtained results demonstrate high efficiency of the chosen treatment method and mode of producing a light ultrafine-grained alloy.

About the Unloading in Elastoplastic Inhomogeneous Bodies

2013 ◽  
Vol 353-356 ◽  
pp. 1267-1270 ◽  
Author(s):  
Vladimir I. Andreev
Keyword(s):  
Plastic Deformation ◽  
Residual Stresses ◽  
Mechanical Characteristics ◽  
Inhomogeneous Bodies ◽  
Secondary Plastic ◽  
The Given

It is generally considered within analysis the residual stresses that unloading occurs on elastic law. For large initial loads, some plasticity theories believe that during unloading secondary plastic deformation can occur. The distinctive work provides a new theorem of unloading, which takes into account irreversible changes in the mechanical characteristics of the material under load. There is an example of the analysis of residual stresses corresponding to the given theorem.

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