Search

Self-assembled porous alumina structures (por Al2O3) were prepared by two-step anodization process and characterized by scanning electron microscopy.Filling quasi one-dimensional parallel nanochannels of por Al2O3 host matrixwith iodine guest substance by vapor phase adsorption method resulted inthe formation of I/por Al2O3 nanocomposite. Electrical properties of thesenanocomposite samples were studied by alternating-current measurements ata frequency of 1 kHz. Ellipsometric measurements were carried out in thespectral range 350–1000 nm. Structural transition of iodine species from thechain structures to molecular iodine was found in I/por Al2O3 nanocompositeat ∼ 70 ◦C.

The vacuum-arc synthesis of nanopowders based on zirconium oxide and metal-organic framework structures was carried out using a low-pressure arc discharge plasma. The obtained material was studied by several methods (XRF, IR, TEM, DTA). The TEM method showed that Zr-MOK is a highly agglomerated particle of an almost spherical shape. The image clearly shows the crystalline ordering of nanoparticles with a large (about 2 nm) lattice parameter. Particle sizes range from 5 to 30 nm. Average particle size 9.4 nm. XRD showed that the proportion of ZrO relative to Zr-MOK, calculated from the most intense lines of the diffractogram, is 65%. XRF results are in good agreement with IR studies. The DTA curve demonstrates a continuous exothermic process associated with a number of features of the plasma-chemical synthesis and morphology of the resulting nanoparticles, which is in full agreement with studies using transmission microscopy.

The article presents the waste generated during the production of hot‑dip galvanizing. The results of the study of the particle size distribution of zinc dust showed that its particle size distribution in the size range of particles ≤ 250 μm, the proportion of which is 87 wt.%, corresponds to the fractional composition of standard powder zinc. In ash, the number of particles up to 250 microns in size is approximately 35 wt.%. Studies of the chemical and phase composition of the hot‑dip galvanized waste – zinc dust made it possible to establish that the zinc content of the waste approximately corresponds to powder zinc (GOST 12601). The proportion of pure zinc in dust is 95 %. Chemical and phase analyzes of the ash have shown that it contains zinc oxides, pure zinc and zinc chlorides. Zinc chlorides, in turn, can be a supplier of chlorine ions in thermal diffusion galvanizing. In this regard, it is of interest to use ash in the composition of the powder composition as an activating and zinc‑containing component. The results of the analysis of the conducted studies of hot‑dip galvanizing wastes – zinc dust and soot show that they are promising for their use as components in saturating mixtures in the production of zinc coatings by chemical‑thermal treatment. This will reduce the cost of galvanized products and ensure the recycling of zinc into industrial circulation.

Self-assembled opal crystals (bulk silica opals and PMMA thin opal films)have been studied by atomic force microscopy (AFM) and optical spec-troscopy. Reflectance and transmittance spectra (R(λ) and T (λ), respectively)as well as spectra of ellipsometric parameters Ψ(λ) and Δ(λ)demonstratepronounced changes with changing the angle of light incidence. Diameters ofspheres obtained from AFM-images correspond to those obtained from Braggfit to the diffraction resonance dispersions. The band of light losses detected byellipsometry at the spectral range of avoided band crossing of opal eigenmodeswas assigned to the energy exchange between these modes

The behavior of a heat-protective ceramic composite material based on ZrO2 fibers in a concentrated solar energy flux under conditions of a strongly nonequilibrium temperature and light field is demonstrated. A change in its structure and morphology depending on the heat treatment temperature is displayed. During an experiment the maximum surface temperature of a specimen based on ZrO2 fibers reaches 1600°C, which is significantly lower than the operating temperature of materials based on ZrO2. As a result of a concentrated flow of solar energy on heat-protective material based on ZrO2 fibers, sintering, shrinkage, deformation, and fracture effects are observed, and the material loses its physical, mechanical and heat insulation properties.

We have achieved a power conversion efficiency of 16.44% for the ternary polymer solar cell using a wide bandgap copolymer and two non-fullerene acceptors.

The influence of the composition of iron-based alloys on the microhardness of the areas of the melted metal in explosion-welded joints with aluminum is investigated. It is shown that, other things being equal, the presence of chromium in the composition of an iron-based alloy leads to an increase in the hardness of the alloys by 1-2 GPa, and joint alloying with chromium and nickel, by 3 GPa.

Cubic, tetragonal, and monoclinic (Bi2O3)x (Nd2O3)y (WO3)z (x + y + z = 1) solid solutions based on the Bi2O3 oxygen ion conductor have been prepared by solid-state reactions in the ternary system Bi2O3–Nd2O3–WO3. The field of monoclinic compounds with a Bi3·24La2W0·76O10.14-type structure has been shown to account for most of the ternary system. Compounds with a cubic fluorite structure exist at the boundary of the monoclinic phase field in two small regions at high (83–91 mol% Bi2O3, δ-phase) and low (20–55 mol% Bi2O3, δ′-phase) Bi concentrations. The cubic samples of the δ-phase retain their structure only during rapid heating and cooling, but annealing in the range of 300–700 °C results in structure degradation to lower symmetry phases. The monoclinic compounds and Bi-poor cubic compounds (δ′-phase) have good thermal stability. The cubic samples of the δ′-phase are hygroscopic. Their bulk conductivity noticeably increases with atmospheric humidity, suggesting that these materials are potential proton conductors.

The characteristics of the external radiation on the surface of the casks for spent nuclear fuel (SNF) storage by dry method are investigated for the case when the spatial distribution of SNF in the basket changes due to the destruction of the fuel rod claddings. The surface areas are determined, where the changes in fluxes of neutrons, produced by 244Cm actinide, and γ-quanta, produced by long-lived isotopes, are maximum in the result of the decrease in the height of the SNF area. Concrete (VSC-24) and metal (SC-21) casks are considered as examples. The procedure of periodic measurement of the dose rate of neutrons or γ-quanta at the specified points of the cask surface is proposed for identifying the fuel rod cladding destruction. Under normal operation, the decrease in the dose rate produced by neutrons as the function of SNF storage duration is determined by the half-life of 244Cm, and for γ-quanta - by the half-lives of long-lived SNF isotopes. Consequently, a stepwise change in the dose rate of neutrons or γ-quanta, detected by the measurements, as compared to the previous one, would indicate the destruction of the fuel rod claddings.

Mathematical analysis of experimental data for low-alloy steel 09G2S austenite recrystallization after hot rolling is provided. An original mathematical model is proposed that relates the volume fraction of recrystallized structure to degree of hot deformation, temperature, and recrystallization annealing duration. The prediction accuracy for this model evaluated in terms of dispersion of deviation for experimental data from predicted results standardized for the average value of experimental results comprises ≈ 20%.

The article considers the results of the study of the uneven distribution of the strength properties of a rigid high-temperature fibrous heat-protective material over the volume of the block. The article presents a comparative study of the uneven strength of two materials that differ in the method of introducing the binder. A conclusion is proposed about the mechanism of the occurrence of unevenness of the strength properties of a rigid fibrous thermal insulation material when a soluble binder is introduced into the material by the strait method. The absence of such a mechanism is shown for materials obtained using a solid-phase binder introduced into the molding hydraulic mass.

The high efficiency of double-crystal X-ray diffractometry and topography methods in the characterization of crystals during refinement of the crystal-growth technology is demonstrated for the example of diamond bulk crystals and films obtained by the high pressure, high temperature method and by chemical vapor deposition, respectively. Techniques and study schemes for analysis of the real crystal structure, assessment of the chemical composition and the period of the crystal lattice, and analysis of the distinctive features of the deformation and thickness of thin films are described. Major structural defects (dislocations, stacking defects, inclusions of a different phase, and others) that emerge during the production of synthetic diamond crystals are identified.

The need to ensure the possibility of widespread use of electronic and mobile health-saving technologies requires not only the formation of an appropriate information technology infrastructure and the development of effective algorithms for processing a large amount of personal information. Development of medical devices for recording physiological processes also involves the creation of innovative biologically compatible materials that allow sensors and medical sensors to work continuously in 24/7 mode. Taking into account the long-term positive experience of using large-capacity thermoplastics and elastomers in medical equipment, it seems promising to use the corresponding polymers as the main materials of wearable electronics for medical purposes. At the same time, to ensure the biological compatibility of the materials under discussion, it is necessary to minimize the possibility of the development of pathogenic microorganisms on surfaces in contact with living tissues. This type of pathogenic organisms (pathogens of a number of dangerous diseases – mycoses) includes some types of microscopic fungi - micromycetes (in particular, Aspergillus niger van Tiegem; Aspergillus terreus Thom; Penicillium cycopium Westling). The article examines the effect of surface modification by gas-phase fluorination on the nature and degree of development of a mixed colony of micromycetes on the surfaces of experimental samples made of several types of thermoplastics (polyvinyl chloride, polypropylene, low-density polyethylene, polyethylene terephthalate) and elastomers (butyl- and butadiene-nitrile rubbers, as well as ethylene, propylene and dicyclopentadiene copolymers). The nature and degree of development of colonies are quantitatively described using the original methodology developed earlier. The effect of fluorination on the nanotexture and chemical composition of the surface and near-surface layers of experimental samples was demonstrated using scanning electron microscopy (SEM) and IR Fourier spectroscopy (IRFS). The dynamics and efficiency of fluorination are described using a linearized hyperbolic model, the parameters of which are set by the least squares method.

The paper presents the results of wear tests for the SMIC of the titanium - iron system, obtained by the technology, including explosion welding and subsequent high-temperature heat treatment, when the abrasive is exposed to the metal-intermetallic layers at an angle of 0, 45 and 90º. It is shown that more uniform wear is observed when an abrasive is applied to the layered structure of SMIC at an angle of 45º. With such a wear pattern, the best indicators of wear resistance are provided, exceeding the corresponding values for 08kp steel and VT1-0 titanium, and having a tendency to increase with increasing test temperature: +7% at 200 °C; + 13% at 400 °C and + 17% at 600 °C.

The results of studies of the structure, chemical and phase composition of the aluminide coating formed on the surface of EP718 alloy after its hot-dip aluminizing are presented. It is shown that the inner layer of the coating consists of a continuous layer of a solid solution based on chromium aluminide CrAl with a monoclinic lattice, in which some of the Cr atoms are replaced by atoms of elements from the EP718 alloy, and the outer layer, which has a pronounced heterogeneous structure, is an aluminum matrix with inclusions of CrAl aluminide. with a lower aluminum content.

One of the significant weaknesses of excimer laser-based vision correction devices is the difficulty of achieving a required change in the refractive properties of the cornea to sharply focus the image on the retina with distance from the working area (ablation zone) center to the periphery due to a change in the laser beam incidence angle. The study is aimed at improving the quality of laser action on the eye cornea by introducing an optical corrective system into the existing excimer laser vision correction equipment, ensuring the coincidence of the direction of the laser beam incidence on the corneal surface with the normal.It has been shown that the greater the reflection coefficient, the lower the absorbed energy, and the shallower the laser radiation penetration and ablation depths, which reduces the laser action opportunities and quality. When using excimer laser vision correction devices, it has been proposed to change the angle of the laser beam incidence on the cornea with a distance from the working area (ablation zone) center to the periphery during the surgery by introducing an optical corrective system based on a lightweight controllable and movable mirror, which allows achieving the coincidence of the direction of the laser beam incidence on the corneal surface with the normal.The studies have shown that the coincidence of the laser beam incidence on the corneal surface at any point with the normal when using a priori data on the specifics of the patient's eye allows expanding the functional opportunities of excimer laser photoablation, i. e., expand the ablation zone by 30 % and eliminate the possibility of errors caused by the human factor. The technique proposed can be used for excimer laser vision correction according to PRK, LASIK, Femto-LASIK, and other methods. To implement this approach, a patented excimer laser vision correction unit has been proposed with a PCcontrolled optical shaping system comprising galvo motor platforms and galvo mirrors installed on them.

Effectiveness of blast furnaces operation in many respects depends on metallurgical properties of agglomerate, in particular, iron content in the sinter and its basicity. At the same time, it is accepted that usage of iron ore concentrates with iron content more than 66–67% for sinter production results in decreasing of its strength. As a result of the planned modernization of the technological sections of the concentration plant JSC “Stoilensky GOK”, iron content in the concentrate will be increased to 68–70%. It makes it actual to accomplish comprehensive studies of metallurgical properties of the sinter while increasing iron content in the raw material. Results of the study of sinter properties presented, the sinter being obtained with utilization of iron concentrate with iron content 66.6 % (base), 68.0 and 69.2 % (exp. 1 and exp. 2 correspondently). The iron ore mixture for all the stages was the same and consisted of iron ore concentrate – 78.3%, sintering ore – 8.0%, lime – 5.5% and sintering additives (sludge, dust, scale) – 8.2%. The sintering mixtures composition for all the study stages differed only by fluxes and iron ore mixture consumption. 18 test sintering operations at three values of basicity 1.6, 1.8 and 2.0 units were accomplished. It was established that increase of iron content in the concentrate and basicity of the sinter results in improving of the sintering process indices, increase of the vertical sintering rate, sintering machines productivity, recovery and the sinter cold strength. Increase of the sinter basicity and its production with increased content of iron results in improving RDI indices at low temperature reducing. Results of the study of porosity indices and metallurgical properties of the sinter presented, in particular the collapsibility during reducing and temperature interval softening-melting presented. The advisability of concentrate with increased iron content utilization in the iron ore mixture shown.

Quantum-sized gold nanoclusters (AuNCs) are emerging as theranostic agents-those that combine diagnostics and therapeutic properties-given their ultrasmall size

The motion of single triple junctions with the [10 $$\bar {1}$$ 0] and [11 $$\bar {2}$$ 0] tilt boundaries is studied. The temperature dependence of the mobility of these triple junctions is found to deviate from the Arrhenius dependence. This behavior is interpreted as the manifestation of a kinetic transition of the junction motion from junction to grain-boundary kinetics. A hysteresis of grain-boundary mobility is observed when a triple junction moves according to the grain-boundary kinetics. When a triple junction moves according to the junction kinetics, no hysteresis of the junction mobility is experimentally detected.

A model has been developed for studying the features of the thermal interaction of molecular oxygen in the near-surface condensation layer in the plasma of a low-pressure arc discharge. It was found that the input power and pressure of the gas mixture exert the main influence on the electron temperature and on the density of positive ions (O_2^+ and O+). It is shown that at a fixed pressure, the ion density increases with an increase in the power of the system, and vice versa.

In this paper, we consider the effect of the introduction of functionally active structures of the supramolecular type on the physical and mechanical, thermophysical and heat-resistant characteristics of elastomeric compositions based on ethylene–propylene–diene rubber. The presence of aluminosilicate microspheres, carbon microfiber, and organophosphorus oligomer in the composition of these structures contributes to the manifestation of a synergistic effect, which consists in increasing the heat-shielding properties of the material due to increasing the strength of the coke and enhancing the processes of carbonization of the material. This leads to an increase in the heating time of the unheated sample surface by 8–17% and a decrease in the rate of linear combustion by 6–17% as compared with known analogues. Microspheres allow compensating the negative effect of microfiber on the density and thermal conductivity of the composition.

The active regulatory basis for the evaluation of the quality of bitumen binders (BBs) is analyzed. A method for evaluating the effectiveness of powder modifiers added to asphalt concrete mixes by the Russian dry process through rheological tests of model binders is proposed. A new criterion for evaluation of the quality of binders is proposed, i.e., the temperature of destruction of BBs during fatigue tests.

The surface of several types of carbon fibers is investigated by means of scanning electron microscopy and atomic force microscopy. Analysis of the images obtained at high magnifications made it possible to establish the characteristic details of the surface relief and employs it for the evaluation of true fiber surface Strue obtained from calculations. Derived from this criterion, a lower limit of adhesive strength measured by the pull-out method is calculated in a “polymer adhesive–fiber with rough surface” joint.

Grafted poly(vinylidene fluoride) (PVDF)-based copolymers attract great attention due to their tunable ferroelectric and dielectric characteristics, which gives great perspectives for electronic applications. In this work, two strategies for polyacrylonitrile-grafted PVDF-based copolymers synthesis, namely single electron transfer radical polymerization (SET-LRP) and photoinduced Cu(II)-mediated reversible deactivation radical polymerization (RDRP) were investigated, their advantages and shortcomings are discussed. Using these methods two series of poly(vinylidene fluoride-co-chlorotrifluoroethylene)-grafted-polyacrylonitrile p(VDF-co-CTFE)-g-PAN and poly(vinylidene fluoride-co-trifluoroethylene-co-chlorotrifluoroethylene)-grafted-polyacrylonitrile p(VDF-co-TrFE-co-CTFE)-g-PAN with different PAN content were prepared. Important characteristics of the grafted PVDF-based copolymers such as phase behavior, thermal stability, and dielectric properties were investigated, and impacts of the macromolecular backbone type, as well as the content of grafted PAN on these properties, are discussed. It was shown that PAN incorporation leads to significant dielectric properties change since the dielectric permittivity of PAN-grafted copolymers is twice higher in comparison to the pristine copolymers. The crucial impact of PAN grafting onto PVDF-based copolymers backbone on their phase, thermal and dielectric behavior is demonstrated.

In this work we investigate the addition of n-methyl pyrrolidone solvent on the morphology of spin-coated graphene oxide film. In order to overcome the poor wettability of polyethylene terephthalat...

This work presents the results of optimization compositions of polymer-modified binder (PMB) by a compromise task. The conducted study of influence two prescription factors – containing styrene-butadiene-styrene and sulfur – on which is a set of indicators of polymer-bitumen binders were carried out. The regularities of these factors of mutual influence were established by such indicators as the Fraas brittleness temperature, penetration, softening point, ductility. The dosages of SBS and sulfur have been determined by ensuring the achievement of the required level of PBB indicators in accordance with GOST R 52056-2003 «Bitumen-polymer road binders are based on styrene-butadiene-styrene block copolymers. Specifications».

A comparative assessment of the effect of two modifiers on the low-temperature properties of BND 90/130 bitumen was investigated using Asphalt Binder Cracking Device (ABCD test) and Dynamic Shear Rheometer (DSR 4-mm test). These modifiers are styrene-butadiene-styrene block copolymer (SBS) and active powder of discretely devulcanized rubber (APDDR) - powder elastomeric modifier obtained by high-temperature shear grinding of waste tire crumb rubber. ABCD results of RTFO-aged samples showed clear and gradual decrease of the ABCD cracking temperature (improvement) for all BC as the modifier concentration increases. It is noteworthy that the Bitumen Composites (modified bitumens) were cracking at higher strain and fracture stress values compared to neat bitumen. Results of DSR-4 mm test showed a decrease in the complex shear modulus (G*), storage modulus (G¢) and loss modulus (G²) BC compared to the neat bitumen. It is shown that bituminous composites have no maximum on the Cole-Cole diagram (dynamic vitrification) at T = -28°C which is observed in the neat bitumen.

The processes of obtaining compositions based on organosilicon resin for a heat-resistant coating of accelerated drying, as well as its hydrophobization by creating an isotropic nano-microstructure on the surface, are studied. It is shown that the chemical nature, the content of the ingredients and the thickness of the coatings have the greatest influence on the physicochemical properties of heat-resistant coatings. The methods of obtaining a composition for heat-resistant coatings using a dissolver and a bead mill in various modes of operation were studied, which allowed us to develop a technological process for manufacturing heat-resistant paint and varnish material. The composition and technology of obtaining a final hydrophobic layer based on a suspension of aerosil HDK 12H and carbon nanoparticles in a fluorine-containing varnish LF 32LN was developed in order to obtain a complex heat-resistant, superhydrophobic and anticorrosive coating for the protection of metal products and its properties were investigated.

The microstructure and mechanical properties of joints made of alloy 6082-T6 obtained by friction stir welding (FST) are investigated. Welded joints have a pronounced heterogeneity in microstructur...

A new X-ray fluorescence (XRF) method is proposed for sample preparation and impurity quantification for elements heavier than sodium in carbon materials. The analysis is suitable for various materials including amorphous ones, such as petroleum cokes, with an impurity content higher than 0.01%. We compared a new method with the regular additive method to measure impurities in electrode graphite and petroleum coke. The XRF-based method provides the same sensitivity and accuracy and much greater reproducibility of the analysis results for variations in the sample mass, its density, and coverage by exciting X-ray radiation. The method does not require changes in the instrument software and is easily implemented on commercial analytical equipment.

The lidar equation for Raman scattering of light by hydrogen fluoride molecules is solved in order to select the laser wavelength and lidar parameters and to obtain a minimum time for measuring the Raman scattering signal corresponding to the minimum concentration of the molecules at the TLV (threshold limit value) level. It is shown that the time for measuring a concentration of 1014 cm–3 HF molecules by this lidar at a laser wavelength of 405 nm and altitude in the 100–1500 m range lies within an interval of 0.04–14.4 s.

The NanoPES photoelectron beamline installed at the Kurchatov Synchrotron Radiation Source is presented. The beamline uses bending magnet radiation of the Sibirea-2 storage ring, and includes grazing incidence monochromator with plane gratings for photon energy range of 25–1500 eV as well as the experimental station designed for investigations using photoelectron spectroscopy and absorption spectroscopy techniques. Capabilities of the experimental station are expanded by electron spectroscopy for chemical analysis and probe microscopy modules.

Abstract The effect of heat treatment on the microstructure, phase composition, mechanical properties, and microhardness of the shape-memory Сu–14 wt % Al–3 wt % Ni alloy prepared in the nanocrystalline state, which results from the severe plastic high-pressure torsion (HPT), is studied. Electron microscopy and X-ray diffraction analysis are used in combination with electrical resistivity measurements in order to obtain data on the peculiarities of thermoelastic martensitic transformations and decomposition in the HPT-processed alloy subjected to thermal actions.

The article presents the results of research on electrically conductive hard-to-burn composite materials based on polyethylene, graphite, and some flame retardants. It is shown that optimal electrical conducting properties and the flammability rating (V0) in accordance with UL 94 test are achieved by modifying the graphite-containing composite material based on low-pressure polyethylene with ammonium polyphosphate and (or) aluminum hydroxide. It is shown that the percolation threshold of a composite material based on high-pressure polyethylene and graphite is observed at significantly higher values of the mass fraction of graphite. It is concluded that the reduction of the percolation threshold of polyethylene when filled with graphite is facilitated by an increase in the degree of crystallinity of the binder, and the formation of structured continuous conducting clusters in the composite material is observed at lower values of the mass fraction of the filler. As a result, the thermal conductivity and heat resistance of the composite material are increased owing to more efficient delocalization of the supplied heat. A number of electrically conductive hard-to-burn materials were obtained and characterized. These data allow us to directly adjust the values of the specific volume electrical resistance, physical and mechanical properties, heat resistance, and, to a certain extent, flame resistance.

We investigate the propagation of laser-induced hypersound waves in polycrystalline diamond films by analyzing the spatial changes in the phase and amplitude of the probing laser beam reflected from the surface. We show that the velocity of bulk (longitudinal) acoustic waves is 14300 m/s in films with an average crystallite size of ≈ 0.2 μm and monotonically increases to 17200 m/s with increase in the crystallite size up to ≈ 2 μm. For surface waves, anomalous dispersion is observed, leading to a change in the phase velocity from ≈ 4800 to ≈ 6600 m/s, which is explained by the effective localization of the surface wave field in the diamond films. The values obtained can be used for the design of diamond films and membranes for applications in diamond photonics and acousto-electronics.

The results of an initial assessment of the possibility of obtaining titanium nitride whiskers from the gas phase are reported. A theoretical assessment was made of the possibility of homogeneous formation of different types of micro-substrates with different compositions in the gas phase and the conditions for condensation of the titanium nitride phase and the growth of whiskers. Based on a thermodynamic analysis of the system under investigation, calculations of the existing critical supersaturations were performed and the homogeneous rate of condensation of titanium and titanium nitride in the gas phase was evaluated.

Data on the morphology of carbon allotrope nanoparticles in an isotactic polypropylene (IPP) matrix are analyzed. They are obtained using the small-angle neutron scattering method and a YuMO spectrometer at the IBR2 reactor of the Frank Laboratory for Neutron Physics, Joint Institute for Nuclear Physics (Dubna, Russian Federation). The fractal dimensionality is calculated, the form is reconstructed, and the geometric dimensions of the obtained particles and aggregates of single-wall carbon nanotubes (SWCNTs) in the IPP volume taken in concentrations of 1.2, 2.6, and 8 wt % are determined using ATSAS software. It is established that nanotubes form fractal nanoobjects with a rough surface in the IPP volume. Composite IPP/SWCNT systems are polydisperse to a significant degree; nanotubes twist into coils and knots and become more densely packed; in the polymer volume, the dimensions of the formed nanoparticles and their aggregates are several times larger than the initial ones used during synthesis. A model of knot formation in polymer materials based on calculating the asymptotic Hopf invariant and the lattice fractal dimensionality is used in this paper to interpret the results and predictions of the possible morphology forming in samples of such a type. The energies and probabilities of knot formation are estimated qualitatively using the Monte Carlo method.

Gear is a mechanical rotating toothed part which meshes with other similar toothed parts to transmit torque and power. Gear tends to play a very vital role in all industries. This article reviews the methodology used to investigate bending strength of asymmetric spur gear; Finite Element Method (FEM), Numerical Calculation and Investigational Techniques were usually carried out in order to understand the bending strength of spur gear. Works and experiment from the literature were studied, and their findings were extracted to understand the methods used. Next stage is to simulate the gear using Finite Element Method (FEM) in order to get the analysis of gear strength. The most important stage is to put the gears to physical experiment or testing facilities to determine and validate all data from the numerical calculation and FEM method. Therefore, this review article highlights importance of asymmetric gear in chronological order so that reader may obtain an overview of contribution of various researchers in development of gears having least bending stress. Keywords: Symmetric gear, Asymmetric gear, Bending stress and FEM.