Oleg I. Lomovsky

Bio: Oleg I. Lomovsky is an academic researcher from Russian Academy of Sciences. The author has contributed to research in topics: Titanium diboride & Copper. The author has an hindex of 15, co-authored 96 publications receiving 769 citations.

Changes in the Crystallinity Degree of Starch Having Different Types of Crystal Structure after Mechanical Pretreatment

Abstract: This paper examines the effect of mechanical activation on the amorphization of starch having different types of crystalline structure (A-type corn starch; B-type potato starch; and C-type tapioca starch). Structural properties of the starches were studied by X-ray diffraction analysis. Mechanical activation in a planetary ball mill reduces the degree of crystallinity in proportion to pretreatment duration. C-type tapioca starch was found to have the highest degree of crystallinity. Energy consumed to achieve complete amorphization of the starches having different types of crystalline structure was measured. The kinetic parameters of the process (the effective rate constants) were determined. The rate constant and the strongest decline in the crystallinity degree after mechanical activation change in the following series: C-type starch, A-type starch, and B-type starch.

Current achievements in the mechanically pretreated conversion of plant biomass

Abstract: At present, "mechanochemistry" is synonymous with "grinding," according to the views of a significant number of scientists and technologists. Often, one comes across the opinion that "the less the particle size, the better." The cases of considering chemical reactions occurring during pretreatment, as well as considering changes in the ultrastructure of cell walls are extremely rare. Also, the wrong choice of the type of mechanical impact and the equipment used in most cases leads to excessive consumption of electrical energy and reduce economic efficiency. The review presents the currently available published data on mechanically activated processes for the pretreatment of plant materials and shows that when using mechanical treatment, it is necessary to look more closely at the phenomena occurring, rather than reducing everything to the production of fine and ultrafine powders. As a result of mechanical action, active surface radicals can form, hydrothermal chemical processes can occur, and mechanocomposites can form. The role of interphase processes, changes in surface chemistry, related dimensional effects, and the disordering of the crystal structure and amorphization should be taken into account. In addition, the physicochemical insights in mechanical pretreatment make it possible to more efficiently use the energy delivered to the material, and, consequently, increase the economic efficiency of the activation process.

Process for electrochemical metallization of dielectrics

Abstract: A solution for electrochemical metallization of dielectrics comprising a salt of copper, a phosphorus-containing salt, a stabilizing agent and water which contains, as the phosphorus-containing salt, a salt of hypophosphorous acid, the components being employed in the following proportions, g/l: copper salt: 35 to 350 hypophosphorous acid salt: 35 to 400 stabilizing agent: 0.004 to 250 water: up to 1 liter. A process for electrochemical metallization of dielectrics involving preparation of the dielectric surface, formation of a current-conducting layer thereon, electrochemical building-up of a metal coating, characterized in that the dielectric surface activation and formation of a current-conducting layer on this surface are effected simultaneously by wetting the dielectric surface with the above-specified solution, followed by a heat-treatment at a temperature within the range of from 80° to 350° C.

Microstructure changes in TiB2-Cu nanocomposite under sintering

Abstract: Stability and growth of nanoparticulate reinforcements in metal matrix composites during heating are widely studied for dispersion-strengthened alloys, which contain several volume percent of reinforcing phase. When high volume content of nanoparticles distributed within a matrix is concerned results of particles aggregation and growth as well as crystallization mechanisms are not so evident. In this work microstructural evolution under sintering in metal-matrix composite TiB2-Cu with high volume content (up to 57%) of titanium diboride nanoparticles 30-50 nm in size was investigated. The nanocomposite powders were produced through synthetic method combining preliminary mechanical treatment of initial powder mixtures in high-energy ball mill, self-propagating exothermic reaction and subsequent mechanical treatment of the product. We focused on microstructure changes in TiB2-Cu nanocomposite consolidated by Spark-Plasma Sintering and conventional sintering and showed that in the former case fine-grained skeleton of titanium diboride is formed with connectivity between particles well established. In the latter case behavior of nanoparticles is surprising: at low temperatures fiber-like structures are formed while increasing temperature causes appearance of faceted crystals. These unusual results allow us to propose the direct involvement of nanoparticles in the processes of crystallization by moving as a whole in the matrix.

1000 at 1000: The effect of electric field and pressure on the synthesis and consolidation of materials: a review of the spark plasma sintering method.

Abstract: The use of electric current to activate the consolidation and reaction-sintering of materials is reviewed with special emphasis of the spark plasma sintering method. The method has been used extensively over the past decade with results showing clear benefits over conventional methods. The review critically examines the important features of this method and their individual roles in the observed enhancement of the consolidation process and the properties of the resulting materials.

Electric Current Activation of Sintering: A Review of the Pulsed Electric Current Sintering Process

Abstract: The phenomenal increase during the past decade in research utilizing pulsed electric current to activate sintering is attributed generally to the intrinsic advantages of the method relative to conventional sintering methods and to the observations of the enhanced properties of materials consolidated by this method. This review focuses on the fundamental aspects of the process, discussing the reported observations and simulation studies in terms of the basic aspects of the process and identifying the intrinsic benefits of the use of the parameters of current (and pulsing), pressure, and heating rate.

Apparatus and method for electrolytically depositing a metal on a microelectronic workpiece

Abstract: A process for applying a metallization interconnect structure to a semiconductor workpiece having a barrier layer deposited on a surface thereof is set forth. The process includes the forming of an ultra-thin metal seed layer on the barrier layer. The ultra-thin seed layer having a thickness of less than or equal to about 500 Angstroms. The ultra-thin seed layer is then enhanced by depositing additional metal thereon to provide an enhanced seed layer. The enhanced seed layer has a thickness at all points on sidewalls of substantially all recessed features distributed within the workpiece that is equal to or greater than about 10% of the nominal seed layer thickness over an exteriorly disposed surface of the workpiece.

Mechanochemistry of Solids: Past, Present, and Prospects

Abstract: A historical retrospective is presented beginning from the early observations by alchemists to the establishment of mechanochemistry as a branch of science. The changes in structure and chemical properties of solids under three-axes loading and by combined action of pressure and shift are demonstrated. The peculiarities of the phenomena taking place upon stressing of particle assemblies in various types of energy-intensive grinding mills are discussed. Based on the contemporary concepts, the mechanism of stress field formation and relaxation is analyzed. Among decisive factors influencing the mechanochemical synthesis, the formation and renewal of contact area between reacting compounds, the explosive evolution of heat, and the feedback phenomenon are emphasized. The perspective directions of practical application in the area known as mechanical alloying, as well as in preparation of functional ceramics and catalysts, and in pharmacy are discussed. The main directions for improving research, construction of milling devices, training of specialists, and exchange of knowledge are proposed.