Papers by Keyword: Structural Materials

Abstract: The high sensitivity of positrons to directly probe atomic scale defects revealing their structure and characteristics makes it a unique tool in materials science research covering all types of materials from hard to soft matter. This review focuses on applications of positron annihilation spectroscopy (PAS) in hard materials. However, it is not intended as a comprehensive review of the foundations of positron annihilation spectroscopy and description of its techniques. These exist in numerous publications cited in this review. Instead, the aim here is to facilitate employing PAS and interpretation of its measurements by illustrating the advantages, limitations, and challenges and guiding the reader on how to overcome technical problems and how to interpret PAS results in meaningful ways. Applications of PAS in electronic and photonic materials, nuclear and irradiated materials, and engineering materials are discussed. Examples are given to guide the reader on how PAS can be combined with complementary methods to uncover the fundamentals of defect physics and reveal interesting new phenomena in condensed matter.

Abstract: Currently, one of the main materials for the construction of buildings and structures is concrete. Improving the performance of concrete is a priority of modern scientific research. Low climatic temperatures, frequent transitions through zero degrees in the autumn-spring seasons, and other aggressive factors have a significant impact on the mechanical and operational properties of structural materials. This work presents the experience of modifying heavy concrete M200 with polymer additive Amokor KM. In the process of two summer field tests, there were obtained data on the persistence of the strength characteristics of the material at test temperatures of-60 and + 20, fractographic studies of the initial and aged samples were carried out, as a result, it was found that the modification positively affects the durability of concrete M200. Additional protective staining increases the durability of the tested materials. Keywords: concrete, strength, composite, compression, modification, durability, fractographic studies.

Abstract: The new method for a comprehensive assessment of the strength, durability and material capacity of the critical elements of the main gas pipelines, taking into account the combined impact of factors causing damage (environment, corrosion, random loading, geometry variation, material defects, etc.), which are changing the bearing capacity and material capacity of these structures, is proposed. As the main damaging factor, the process of corrosion fatigue is accepted, the qualitative and quantitative assessment of which are realized by applying a set of equations of comparable fatigue lines obtained by fatigue tests carried out in air and in corrosive environment. By the joint solution of these equations, the functions of the corrosion action coefficients are obtained in a wide range of cyclic strength and durability, which in standard calculation procedures are performed only for cyclic strength and only at the inflection point of the fatigue lines (N_G  5  10⁶ cycles).The issues of reducing the material consumption and ensuring the cost-effectiveness of structures, by using relatively cheap materials for pipelines - low-carbon and low-alloy structural steels subjected to surface hardening in stressed sections of pipes (edge welds) in order to significantly increase the physical and mechanical characteristics of the used steel grades are considered. In order to increase the corrosion resistance of these sections, contemporary polymer anticorrosive coatings are used.

Abstract: The modern building materials market places high demands on heat-insulating and heat-insulating structural materials. In this connection, the issues of developing high-quality building materials obtained on the resource-saving technologies basis allowing to solve two interrelated problems are topical. The first problem is the industrial waste generated and existing stocks disposal. The second is associated with a decrease in the traditional raw materials deficit [1]. These problems solution, combining rational technological solutions, is based on the scientific research achievements in this area, in particular in the foam glass production. The priority scientific research areas in the foam glass materials production are the developments related to the study, the new raw materials use and the production of foam glass mixture compositions on their basis, which provide, along with the necessary performance properties, high environmental safety requirements [2, 3].

Abstract: Tb (AUFA)₃2H₂O, a rare earth terbium complex,was synthesized by introducing 4-(11-azobenzene-undecyloxy) ferrocene acid (AUFA) as the ligand. This complex was characterized by elemental analysis, MS, IR, Raman, UV spectroscopy and fluorescence spectrophotometry. The complex exhibited ligand-sensitized green emission, and Tb (AUFA)₃2H₂O had a higher sensitized luminescence efficiency and a longer lifetime than the other terbium complexes (DPC: 2, 6-Pyridinedicarboxylic acid, Aspirin: 2-ethanoylhydroxybenzoic acid). The organic-inorganic thin film of complexe Tb (AUFA)₃2H₂O in nanoTiO₂ was fabricated, and the nanoTiO₂ has been used in the luminescence layer to change the luminescence property of complexes Tb (AUFA)₃2H₂O. It was found that there was an efficient energy transfer process between the ligands and metal ions. Moreover, In an ITO/PVK/Tb (AUFA)₃2H₂O/Al device, Tb³⁺ may be excited by intramolecular energy transfer from the ligand, as observed by electroluminescence. The main emitting peak at 545 nm can be attributed to the ⁵D₄→⁷F₅ transition of the Tb³⁺ ion, and this process results in the enhancement of the green emission from the electroluminescence device.

Abstract: Nowadays application and development of cognitive graphic tools for the usage in intelligent system of data and knowledge analysis, decision-making and its justification for different problem areas including material research are urgency. Most significantly developed cognitive graphics tools based on n-simplex which are invariant to problem areas are presented. Specificity of program realization of cognitive graphics tools which is invariant to problem areas is described. Most significant results are given and discussed. Future investigations are connected with the usage of new approach to rendering, cross-platform realization, improving cognitive features and expanding n-simplex family

Abstract: Sustainable exploration and use of energy source depend on discovery of new energy source and development of novel energy devices. As a kind of energy storage device, supercapacitors have many advantages over conventional batteries: high power density, long cycling stability, fast charge-discharge rate and being environment friendly. However, common problems involved with nanomaterials such as bad structural continuity, conglomeration and structural instability have restricted their application in supercapacitors. We have conducted the design, synthesis and performance research of the electrode materials containing. We demonstrate the above composite materials have wide prospect for application in the supercapacitors as well as other similar fields.

Abstract: The analysis of structural materials, especially the theoretical research, is always a challenge. Starting from the structural characteristics of the material, the theory of full state function about the strength - stiffness - strain that reflects the properties of structural material is established on the basis of the structural state of the material. The full state function is an important method to solve this problem. In order to further analyze the characteristics of the full state function, the full state function, strength theory of the material and the constitutive relation found are first studied. It is found that the full state function can more comprehensively reflect the properties of the structural material. The full state function accommodates the strength theory in the classical elastic-plastic theory. The full constitutive relation of the materials can be derived from the full state function. That is to say, the full state function can unify the strength theory and constitutive relation in the classical theory and can be used for the analysis of the structural materials. The full state function is more than a mere form, because it has explicit physical and mechanical meanings.

Abstract: Strength criteria for materials in the classical elastoplastic theory are formed mostly based on experiments and some assumptions [1, . However, no concensus has been achieved though many strength models were put forward to explore the applicable material strength criteria previously. Even the influence of material structures on strength has not been realized. In this article, the tensile failure strength criterion, shear strength criterion and strength criterion of friction materials are explored on the basis of the model of material with a structure of uniformly random distribution. Through analysis, it can be discovered that the strength criteria in the classical elastoplastic theory can be derived from the complex material theory based on the concept of material structure. However, as the theoretical basis, conditions of derivation and assumptions of concepts are totally different, it is proved that the complex material theory used for studying the material structures can fully cover the contents and conclusions obtained in classical elastoplastic theory.

Abstract: Stainless Steel is a family of versatile materials that has been put into a wide variety of application by mankind. Stainless steels are iron-based alloys containing minimum 12% chromium and upto 25% nickel with minor additions of carbon, nitrogen, molybdenum, tungsten, titanium, niobium, copper and selenium. It has a wide range of applications from small pins to the construction of automobiles, petrochemical, space, aeronautical, ship building industries, nuclear and thermal power stations. Certain grades of stainless steels, because of their biocompatibility are used for manufacture of biomedical implants. In fact steel touches every sphere of our daily life. By and large stainless steel family consists of hundreds of grades with varieties of compositions and a large spectrum of mechanical properties. The corrosion and oxidation resistance of stainless steels have been significantly improved through fine-tuned chemical compositions and microstructural constituents, leading to the evolution of super stainless steels. Stainless steel development from design to application is a long-term continuous effort. The recent advances in stainless steels are mainly due to new ways of manufacture, processing and usage of advanced equipments. In spite of inroads by a range of competing materials, stainless steels occupy an important place as structural materials, because of their outstanding strength to weight ratios, ductility, fracture toughness, repairability, corrosion, etc for a given cost. Over the years, MIDHANI has catered to the requirements of Indian Space, Nuclear, Thermal, aeronautical and Defence sector for many high performance materials. A wide range of special stainless steels many of them being tailor made to customers specific needs have been developed and supplied. This has been possible with the help of state of the art facility and excellent quality assurance system available in MIDHANI. The presentation will high light MIDHANI role in development and commercial production of different varieties of stainless steels for critical applications.