The mechanisms of magnetite oxidation (forward reaction) and hematite dissociation (reverse reaction) are considered in terms of a general kinetic approach. The dissociation in a pellet is found to develop during sintering when temperature increases. A derivatograph is used to perform experiments with Kachkanar fluxed pellets at various heating rates in a gas containing various oxygen contents. The reaction surface and the dissociation rate are found to increase with the temperature and the slag-forming oxide content. The heating of samples in a reducing atmosphere is studied. The temperature range of reduction of partially dissociated pellets, in which their intense destruction induced by the hematite–magnetite transition does not occur, has been determined. Based on the results of analyzing the pore structure of a pellet, we conclude that, when a melt appears in the system, the dissociation in a pellet is associated with both liquid-phase sintering, when closed porosity forms, and an increase in temperature. The results obtained in this work are of great practical importance, since the use of partially dissociated pellets excludes hematite reduction in them at low temperatures and does not lead to a violation of the gasdynamic conditions of blast-furnace melting.
This article presents the results of hybrid treatment (cold working, ESA) of 09G2S structural low alloyed steel aimed at improving operation reliability.
Carbide–boride coatings applied on both sides of V96Ts aluminum alloy samples by electric spark alloying (ESA) are metallographically studied. The coated samples are processed by laser on one side. Laser treatment of the surface decreases the pronounced roughness, pores, and cracks visible after ESA. Laboratory tests suggest combined (electric-spark–laser) hardening of the surface of V96Ts aluminum alloy samples to extend the service life of tools and machine parts.
Introduction. In today’s knowledge society, the amount of scientificapplied information, which university graduates have to acquire, continues to increase continuously. There is a concurrent reduction in the number of study hours to undertake educational programmes in order to increase the hours for students’ independent work. Against this background, higher school is required to increase future experts’ competencies. Therefore, the content of fundamental and special disciplines of entire period of training and independent work of students should be thoroughly coordinated by increasing students’ motivation to self-education and self-development. Classroom-based and independent learning of disciplines and sections of fundamental academic courses, especially chemistry, is impossible without formation of students’ scientific thinking. Today, it is difficult to consider the activity of most professionals without the ability to think scientifically: active expansion of science into professional sphere has a strong tendency to be increased. The aim of the present research is to show the possibilities of formation and development of scientific thinking in the students of natural-scientific and technical directions of education using the example of studying of one of the elements of programmes in chemistry (the method of nuclear magnetic resonance (NMR) analysis). Methodology and research methods . The research was carried out on the basis of competency-based, systematic and interdisciplinary approaches. The methods of analysis, synthesis, integration, differentiation and compactification of fundamental knowledge and training material were used. Results and scientific novelty. The high potential of chemical education for formation of scientific thinking, subject content (chemical), natural-scientific and holistic scientific thinking is emphasised. However, chemistry education in higher education institution is complicated by the absence of the unified structure of fundamental preparation, the preservation of extensive approach to the content of chemical disciplines, the irrational organisation of students’ independent work, which now is accounted for a half of instructional time. Overcoming these problems lies in the dialectic unity of fundamental and practice-oriented knowledge, which is provided by the compliance with the principles of continuity and interdisciplinarity. It is necessary to provide deductive structurisation of training material in order to give integrity and systemacity to the content of education, without which it is impossible to create a comprehensive natural-scientific picture of the world in students. The key initial element of vocational training stimulating the formation of reflexive skills and scientific thinking of future experts is mastering by students of a categoricalconceptual framework of science, which is consistently and comprehensively revealed throughout a high school stage of education. The authors designated phases of development of scientific thinking (formal-logical, reflexive-theoretical, hypotheticodeductive thinking), which are not clearly differentiated due to interpenetration and entanglement of their components and identity of thought processes in terms of their speed and quality. However, the allocation of these stages allows to structure and to correct the content of educational material taking into account the characteristics and the level of students’ readiness. From these standpoints, the expediency of more detailed examination of the NMR method is proved within the disciplines such as “Chemistry”, “General Chemistry”, “Inorganic Chemistry” and “Analytical Chemistry” (a part of material about the NMR method can be worked out by students independently). This method, based on one phenomenon, includes hundreds of various types of the experiments, which are intended for receiving particular information. The NMR method is widely used both in scientific research, including master’s thesis, and in the most various manufacturing spheres. Today, the spectroscopy of NMR is recognised as the most powerful informative and perspective method of structural analysis of substance. The fundamental nature, interdisciplinarity and universality of the method provide students with basic professional knowledge on physics, chemistry, medicine, biology, technology and ecology. The authors of the present research propose the option of configuration of educational information on NMR. According to the suggested version, the principle of work is the following: firstly, bachelors study the system of key concepts and terms, moving gradually from formal-logical to substantial generalisations; then, students learn to explain the phenomena scientifically and to make forecasts, and, as a result, they become the “owners” of hypothetico-deductive thinking. The acquired competencies are the key to professional literacy, which is improved in master’s degree programme, when the previously compactified scientific knowledge in a contracted form is developed in the form suitable for an optimal solution of a particular research or practical aim. The similar scheme of vocational training makes it possible to overcome traditional orientation of high school programmes of the natural-science block (i.e. retention of permanently growing amount of factual material). Practical significance . The research materials can be useful for methodologists of the higher school, for experts engaged in methodological development and the organisation of educational process, for high school teachers of chemistry and related disciplines, for post-graduate students and master’s students of chemical and chemico-technological specialties as well.
The preparation of inorganic brown pigment from red mud is investigated. The results of the phase and chemical analyses of raw material and the product are given. A flow diagram is proposed and the parameters of the pigment production are recommended. This approach has provided a pigment of pure color with the opacity of 8 to 10 g m –2 from red mud (up to 80%) without additives and the reduction of Fe(III) into Fe(II) using sulfide sulfur.
Introduction. In Federal State Standards of the Higher Education (FSS HE) of the natural-science and technical specialties and also in a number of the corresponding professional standards, the competence in the field of analytical chemistry is specified as one of the main qualification characteristics of an expert/university graduate. It is caused by interdisciplinarity of analytical chemistry and a wide range of application of analysis methods which are used today not only directly on chemical production, but also in power engineering, construction engineering, metallurgy, materials science, standardization, certification, and many other spheres. At the current time, however, there is a big gap between achievements of chemical science and content of high school discipline that reduces quality of staff training demanded in labour market. This discrepancy is caused both by preservation of traditional methodology of teaching chemistry and the reasons of the methodical plan. The aim of the publication is to search for more effective and productive ways of mastering the educational material that is relevant for acquiring the qualifications required from the university graduate. Methodology and research methods. Methodological framework of the article involves the concepts of chemical and natural-science education at the higher school; the principles of the system-based, cognitive, practice-focused and competence-based training. Results and scientific novelty. On the basis of the review and generalization of scientific and methodological resources on the theory and practice of application of the analysis methods of substances from didactic positions, a number of these methods have been singled out and compared; their role and features in determination of a molecule structure and other characteristics of an individual substance and its solutions have been shown. Despite the fact that the work is carried out using known methods of analysis, such a generalization makes it possible to more clearly understand the principles of the choice of a method and the method importance according to the purposes and specifics of the studied object that is essential for formation of research skills during training, as well as for formation of scientific thinking and the required qualification acquisition by graduates of the natural-science and technical specialties. In order to update the acquired knowledge, the examples illustrating applied use of various analysis methods in modern research and production practice have been collected. Tables have been made for a faster perception of the material by methods of analysis for the purpose of an informed choice of the method. Reliance on the principle of tabular collection of material makes it easier to understand the individuality of the method; allows teachers to reduce their workload; and on the part of students, to shorten the time and simplify the procedure of choosing the method of chemical, physicochemical and/or physical analysis. Practical significance. The work is compiled in accordance with the State General Educational Standards of Higher Professional Education, and can be recommended to practising and beginning teachers of higher education institutions, as well as graduate students of chemical specialties. The materials presented in the article can assist in designing the curricula of chemical disciplines or modules of educational programs.
The high-temperature hydrolysis of magnesium nitrate hexahydrate is studied. The presence of basic magnesium nitrate in the decomposition product at 160°C is found by IR spectroscopy and X-ray diffraction analysis. A mechanism for the high-temperature hydrolysis of Mg(NO 3 ) 2 · 6H 2 O is proposed.
The aim of the investigation is to show the possibility of updating of the training program of the discipline «Chemistry» intended for training of engineers of chemical specialties of higher educational institutions on the basis of results of the last researches in the field of nanochemistry. The article is addressed to the scientists and teachers developing the specific fields of science, to students and graduate students who have decided to devote themselves to new perspective science of the 21st century. Methods. The analysis of the works concerning the combinational scattering method (Raman spectroscopy) is made. Exposure to the combinational scattering method and the method of infrared spectroscopy is necessary for the undergraduates who are engaged in synthesis of new nanomaterials on the basis of carbon while deciding of the obtained experimental data. The physical and chemical analysis was used in the research to study the properties and structure of shungite of the Zazhoginsky field – the unique natural mineral containing nanoparticles and the effective sorbent applied to purification of drinking water (emission spectral analysis with inductively coupled plasma, Raman spectroscopy and Infrared spectroscopy). Results and scientific novelty. When processing shungite with toluene, ochroleucous resinous substance was educed; this is an organic substance according to data of IR-spectroscopy. On the basis of the analysis of data of Ramanspectroscopy, the line about 2700 cm–1 is offered to consider as the indicator of crystallinity. A variety of physical and chemical and structural properties in connection on the basis of shungite allows us to speak about chemistry of fullerenes and nanochemistry as the new perspective direction of chemistry. Practical significance. Described data on Raman-spectroscopy will help undergraduates, young scientists and researchers to identify various modifications of carbon in the nanomaterials synthesized by them on the basis of carbon. The data received during the research can be used for laboratory work «Determination of shungit nanocomponents through modern physical and chemical methods», having included it in the subject «Carbon» of the program of discipline «Chemistry». The materials of the article can also serve as a starting point for creation of a special short-term course on studying of materials of group of carbon in the system of advanced training for employees of the entities who are engaged in shungite processing.
The aim of the investigation is to show the possibility of updating of the training program of the discipline «Chemistry» intended for training of engineers of chemical specialties of higher educational institutions on the basis of results of the last researches in the field of nanochemistry. The article is addressed to the scientists and teachers developing the specific fields of science, to students and graduate students who have decided to devote themselves to new perspective science of the 21st century.Methods. The analysis of the works concerning the combinational scattering method (Raman spectroscopy) is made. Exposure to the combinational scattering method and the method of infrared spectroscopy is necessary for the undergraduates who are engaged in synthesis of new nanomaterials on the basis of carbon while deciding of the obtained experimental data. The physical and chemical analysis was used in the research to study the properties and structure of shungite of the Zazhoginsky field – the unique natural mineral containing nanoparticles and the effective sorbent applied to purification of drinking water (emission spectral analysis with inductively coupled plasma, Raman spectroscopy and Infrared spectroscopy).Results and scientific novelty. When processing shungite with toluene, ochroleucous resinous substance was educed; this is an organic substance according to data of IR-spectroscopy. On the basis of the analysis of data of Ramanspectroscopy, the line about 2700 cm–1 is offered to consider as the indicator of crystallinity. A variety of physical and chemical and structural properties in connection on the basis of shungite allows us to speak about chemistry of fullerenes and nanochemistry as the new perspective direction of chemistry.Practical significance. Described data on Raman-spectroscopy will help undergraduates, young scientists and researchers to identify various modifications of carbon in the nanomaterials synthesized by them on the basis of carbon. The data received during the research can be used for laboratory work «Determination of shungit nanocomponents through modern physical and chemical methods», having included it in the subject «Carbon» of the program of discipline «Chemistry». The materials of the article can also serve as a starting point for creation of a special short-term course on studying of materials of group of carbon in the system of advanced training for employees of the entities who are engaged in shungite processing.
Differential scanning calorimetry data are presented for the 01979 alloy produced by granular technology. The optimum quenching temperature is confirmed. Strengthening phases dissolve most completely at this temperature. The phase composition of the high-strength aluminum alloy is studied using scanning microscopy and electron microprobe analysis. The AlCu4, AlCr2, and MgZn2 phases and their interplanar spacings are determined.
Представлены результаты по изучению фазового состава высокопрочного алюминиевого сплава 01979, полученного по гранульной технологии. Методами растровой микроскопии и рентгеноспектрального анализа определены фазы AlCu 4, AlCr 2, и MgZn 2 и межплоскостные расстояния их кристаллических решеток.
The phase composition of a high-strength 01979 aluminum alloy produced by granular technology is studied. The AlCu4, AlCr2, and MgZn2 phases and the interplanar spacings of their crystal lattices are determined by scanning electron microscopy and electron-probe microanalysis.
Production of inorganic pigments was studied, and specifically that of iron oxide black pigment, which can be used in paint-and-varnish industry and in manufacture of building and other pigmented materials. Results are presented of phase and chemical analyses of raw materials and final product. A technological scheme is suggested and production parameters of the black pigment from red mud are recommended. The pigment is produced from the −0.045 mm fraction of red mud, a waste from alumina industry. It is recommended to perform calcination at 850°C in a controlled atmosphere with deficiency of oxygen. This method yields an iron oxide pigment of purely black color with a coverage power of 8–10 g m −2 from a waste produced in manufacture of alumina, red mud (up to 90%), without additional additives and provides reduction of Fe(III) to Fe(II) by the sulfide sulfur present in the starting mud.
Разработан способ восстановления эксплуатационных свойств твердосплавных пластинок из сплавов ВК при помощи предварительной цементации с последующим электроискровым легированием сплавом ВТ1-0. Исследован фазовый состав в зависимости от времени электроискровой обработки.
A method is developed to restore the service properties of VK hard alloy plates using preliminary carburizing followed by spark alloying with a VT1-0 alloy. The phase composition is studied as a function of the spark treatment time.