Materials Science. Non-Equilibrium Phase Transformations.
Vol. 3 (2017), Issue 2

Table of Contents

  • INNOVATIVE DEVELOPMENTS OF THE INSITUTINS OF METALLURGICAL PROFILE OF THE RUSSIAN ACADEMY OF SCIENCES

    pg(s) 40-41

    In the present work, examples of the successful development of new materials and technologies on the basis of fundamental research by members of the Russian Academy of Sciences are outlined. The topics include anticorrosive protective coatings based on ultrafine Zn powders; catalytic converters for vehicle exhaust gases; nanostructured stents for endovascular operations; and corrosion and wear resistant coatings and corresponding methods of plasma application. Methods have been developed for recycling of oily scale; for special electroproduction of steel for the power industry; synthesis of massive monocrystalline samples of transition metal nitrides and nanopowders of W, Pt, and Ti and their carbides and nitrides and others.

  • IMPROVEMENT OF OPTICAL CHARACTERISTICS OF COMPONENTS OF OPTOELECTRONIC DEVICES IN THE HARSH CONDITIONS OF THEIR FUNCTIONING BY USING ELECTRON BEAM TECHNOLOGY

    pg(s) 42-48

    The optimal parameters of the ranges of the electron beam are found (heat density, velocity, displacement), within which there is improvement of the physical and mechanical properties of surface layers of optical elements: there is no formation of negative defects on their surfaces which become atomically smooth (residual microscopic ridges do not exceed 0.5… 1.5 nm); the microhardness of the surface increases, hardened layers are formed with compressive stresses. This leads to the reduction of the light scattering coefficient of surface layers of elements and increase of their coefficient of infrared radiation transmittance and, ultimately, to the improvement of metrological characteristics and reliability of devices under intensive external thermal action.

  • ADHESION STRENGTH EVALUATION OF CERAMIC COATINGS ON CAST AND SELECTIVE LASER MELTED Co-Cr DENTAL ALLOYS USING TENSILE SPECIMENS

    pg(s) 49-52

    Studying the fracture characteristics of porcelain coatings plays a main role in selection of materials for metal-ceramic restorations. The aim of this work is to study the effect of the substrate manufacturing process on the adherence of the porcelain. The coatings of porcelain IPS.Inline (Ivoclar Vivadent) are fused onto dental Co-Cr alloys fabricated via casting (Biosil F) and Selective Laser Melting (SLM) (Co212-f). The adhesion strength of the ceramic coatings is studied under tensile load of flat specimens. The interfacial shear strength is determined using experimental results. The shear stress distributions in the metal-ceramic interface at the critical load are evaluated by analytical approach. It is established that the interfacial shear strength values of ceramic coating are 67.5 MPa for cast Biosil F alloy and 83.8 MPa for SLM Co212-f alloy. The higher shear strength of the porcelain to the SLM samples is due to the nearly two times higher surface roughness, which is reason for increasing both the mechanical and the chemical adhesion. The nature of the fracture of the ceramic coating on the Co-Cr alloys, produced by casting and SLM, is similar and is mixed adhesive–cohesive mode. The higher adhesion strength of the porcelain coating to the SLM dental alloy is a good precondition for the SLM application in production of metal-ceramic fixed partial dentures for areas with heavy loads.

  • PECULIARITIES OF METALIZED SURFACES MODIFICATION OF SILICON ELEMENTS OF MICROELECTROMECHANICAL SYSTEMS WITH LOW-POWER ELECTRONIC FLOW

    pg(s) 53-55

    The practical possibility of the atomic force microscopy method to evaluate uniformity of thin metal coatings on silicon wafers after electronic processing has been shown in the paper. It is established that after processing of metallized surfaces of silicon plates Kp0 by an electronic flow of continuous form, the microroughness decreases in 10-15 times and the Adhesive strength increases in 1.8-2 times. At the same time, it is noted that the surface of metal coatings on silicon after electronic processing has a more homogeneous structure and released from microdefects, unlike metallized coatings without electronic processing.

  • DEVELOPMENT OF MATHEMATICAL MODELS OF THERMAL PLASMA PROCESSES

    pg(s) 56-59

    Application of a mathematical modelling of thermal plasma processes is effectively during development and optimization of electric power equipment as well as electro technological equipment. In the field of electric power industry such devices are: circuit breakers (simulation of arc extinction in the arc chamber); multi-chamber arresters for lightning protection of overhead power lines (simulation of arc discharge in a chamber of the arrester), and others. In the field of electro technological equipment such devices are: DC (and AC) arc plasma torches for air-plasma spraying of coating, metal welding and cutting; ICP (inductively coupled) plasma torches for nanomaterials production, fine powder treatment, plasma-chemical technologies and others. The article describes the main stages of the development of mathematical models: a study of the features of the physical process that allows us to formulate the basic assumptions of the model (stationary or non-stationary process, 2D or 3D geometry, laminar or turbulent flows and others); construction of the computational domain and of the mesh; setting the boundary conditions. Examples of results of calculations are shown. Recommendations on the use of specialized software are presented.

  • INVESSTIGATION OF MICROSTRUCTURAL AND MECHANICAL PROPERTIES OF DIFFERENT TYPE OF CASTINGS

    pg(s) 60-64

    In this research work are presented results and procedure for investigations different types of castings in order to check their properties according to appropriate standards, to identify type of unknown casting, to detect and analyze different type of defects in castings and to perform failure analyze in order to determine the reasons for fracture. Presented investigations are basic research activities which are performed almost in all research laboratories for investigations of castings.

    They mainly consist of identification of visual inspection, investigation of chemical composition, investigation of mechanical properties and microstructural identification. Completing of the results from performed investigations and their analysis required information about investigated casting can be obtained.

    In this research work are given result of investigations of three castings GJS- 450-10 cast iron, malleable cast iron and Hadfield steel casting.

  • CORROSION BEHAVIOR OF COMMERCIALLY-PURE TITAMIUM WITH DIFFERENT MICROSTRUCTURES

    pg(s) 65-69

    This paper reports on the results of corrosion tests, using alternative methods, of Grade 4 CP Ti samples with coarse-grained (annealed) and ultrafine-grained structures after severe plastic deformation processing. The effect of microstructure on the corrosion of the material under study is demonstrated. It is revealed that the material with a UFG structure has a higher corrosion resistance, as compared to the samples with a CG structure.

  • MICROALLOYED STEEL UNDER TENSION AND BENDING CONDITION

    pg(s) 70-73

    The article deals with the influence of the loading rate in the interval from 1 to 1000 mm/min on the mechanical properties of drawing steel sheet, used for the manufacture of automotive parts, under tension and bending conditions. It describes the aspects of material characteristics under tension and bending conditions, while bending tests were made on notched specimens (a modified impact bending test). With an increasing strain rate up to the critical value, the resistance of material against strain increases and hence the yield point and the tensile strength increase, the deformation ability, the deformation homogeneity, the structure and the substructure after deformation, etc. Are changed. The paper presents knowledge that using a modified notch toughness test it is possible to achieve the formability characteristics corresponding to dynamic strain rates even under the static loading.

  • FINITE ELEMENT MODELING OF INCREMENTAL SHEET METAL FORMING OF ALUMINUM ALLOY AL 1100

    pg(s) 74-77

    Incremental sheet metal forming has been well-known as one of the flexible methods of forming metallic sheets, suitable for the production of prototypes or small batch sizes. Apprehending the deformation method in forming processes and selection of route parameters to avoid part failure are of vital importance, because marketing needs standard sound parts in a shortest possible time. This paper presents the study on the use of finite element modeling of incremental sheet metal forming of Al 1100 aluminum alloy to investigate the effect of tool diameter and step over on the forming induced stresses, part thickness distribution and forming forces. The results of finite element analysis are compared with experimental data while producing truncated pyramid parts. It has been shown that the developed finite element model is capable of providing reliable results in the prediction of the final thickness of the part, which matches the experimental results with a maximum discrepancy of 8%.