bluuebunny/crossref_metadata_2025 huggingface dataset:
DETERMINATION OF THE OPTIMAL PARAMETERS OF LASER BORIDING TO IMPROVE THE WEAR RESISTANCE OF PISTON RINGS
Authors: Glushkova D. , Volchuk V.
Published: January 2023

Purpose. The goal was to determine the effect of laser heating parameters on the structure and depth of the borated layer, since the properties of piston rings depend on the depth of the latter.

Research methods. Microstructural and X- ray phase analyzes were used to determine the structural state of piston rings.

Results. Application of traditional boriding methods associated with diffusion of boron into the solid phase leads to formation of the working layer having high brittleness. The conducted studies revealed that the increase in the speed of displacement of the part in the process of laser heating reduces the depth of the borated layer. Such a dependence is observed both at 0.15 mm thickness of coating and at a thickness of 0.30 mm. For all modes of workpiece displacement speed for the used boron containing envelope with the above-specified thickness a higher thickness of the borated layer and the heat affected area corresponds to a higher thickness of coating. Increase of the spot size leads to an increase in the depth of the layer. By X- ray and metallographic diffraction there were decoded the phases and structural constituents of the borated layer.

Scientific novelty. An approach to solving the problem of increasing the wear resistance of piston rings without crumbling is shown. The use of laser heating during drilling ensures the formation of a new layer with special properties. However, optimal properties can be achieved only after establishing a relationship between the parameters of the process and the depth of the boron layer. X-ray and metallographic analysis determined the relationship between the rate of irradiation and the proportion of high-boron structures in the layer. It is shown that the borated layer in high-strength cast iron contains such phases as FeB, Fe2B, α- phase, borocementite Fe3(B,C).

Practical value. Increased wear resistance of piston ring materials, which often limits the growth of machine productivity and their service life. Research results can be extended to other parts subject to intensive wear.
NHSR 181: Emergency Department Visits Related to Mental Health Disorders Among Adults, by Race and Hispanic Ethnicity: United States, 2018-2020
Authors: Peters J. Zachary , Santo Loredana , Davis Danielle , DeFrances J. Carol
Published: January 2023

This report describes emergency department (ED) visits related to mental health disorders among adults and assesses differences in mental health-related ED visit characteristics by race and Hispanic ethnicity.
Religiosity of the prospective members of the Stańczycy group in their youth in comparison with their later religious views
Authors: Gancewski Mateusz Piotr
Published: January 2023

This article discusses the religious views of Stanisław Koźmian, Ludwik Wodzicki and Stanisław Tarnowski, as well as the shape of their piety before the January Uprising. The religiousness of their youth was confronted and compared with their later religious views, which allowed for a change in their views over the years.This work begins with a discussion of the spiritual formation of the heroes of this article, which was greatly influenced by the family environment in which they were brought up - an environment of patriotic nobility and aristocracy, sincerely devoted to Catholicism (for personal and national reasons). However, despite their attachment to religion and fulfilment of religious practices (especially in the case of Stanisław Tarnowski and Ludwik Wodzicki), the future Staśniks were not uncritically inclined towards the Catholic Church. On the contrary - just like the majority of the generation to which they belonged - they often expressed negative opinions about the moral condition of the clergy, and were opposed to the secular power of the Pope, which put them in opposition to ultra-Montane members of their families and some members of the Hotel Lambert - the organisation with which they were ideologically and politically associated.After the January Uprising there was a gradual evolution of their views towards almost complete obedience to the institutional Church. Nevertheless, for several more years their religious outlook was marked by a certain liberalism, and their views on the behaviour of the Catholic Church were often critical, which resulted in accusations of moderantism being levelled at them by the ultramontane milieu of the "Przeglad Lwowski".
A POLÍTICA EDUCACIONAL NO BRASIL E SUA RELAÇÃO COM O CURRÍCULO NA FORMAÇÃO DE PROFESSORES
Authors: Rabelo Islei Gonçalves , Santos Francely Aparecida dos
Published: January 2023

Este artigo é um recorte de uma pesquisa de Mestrado realizada no curso de Pedagogia da Universidade Estadual de Montes Claros (Unimontes), no ano de 2020. O objeto de estudo foi a relação de teoria e prática no curso de Pedagogia, de modo a refletir a formação de professores. O estudo teve como objetivo distinguir a concepção de teoria e prática que está inserida nos documentos curriculares oficiais que organizam e constituem o referido curso. O processo metodológico ancorou-se na revisão de literatura e na pesquisa de campo por meio do procedimento de análise documental realizada no Projeto Político-Curricular (PPC) do curso de Pedagogia e nas Diretrizes Curriculares Nacionais (DCN) para a formação de professores. A perspectiva de análise sustentou-se na premissa de que, se a educação é um ato político e o alcance da prática pedagógica se concretiza na prática social, possivelmente, a formação de professores se ergue por meio do conceito que as políticas públicas têm de educação, sujeito e sociedade. Logo, as políticas educacionais para a formação de professores se efetivam, também, por meio das políticas públicas curriculares cujos princípios, fundamentos e procedimentos são constituídos a partir das DCN para a formação docente. A investigação evidenciou que a possibilidade de transformação da sociedade contemporânea, que massifica e oprime a classe popular, pode estar, também, no processo educacional, cuja contribuição do professor seja capaz de refletir, construir e operacionalizar uma prática pedagógica que vincule sua ação docente intencionalmente à prática social.
JOGOS DIGITAIS E APRENDIZAGEM EM QUÍMICA: UMA ANÁLISE A PARTIR DA REVISÃO SISTEMÁTICA DA LITERATURA
Authors: Pacheco Alan , Costa Hawbertt Rocha
Published: January 2023

Este trabalho tem o objetivo de investigar de que forma a utilização dos jogos digitais contribuía com a aprendizagem dos alunos de Química, a partir da análise da produção acadêmica publicada em bases de dados eletrônicas. Para isto, a coleta de dados se deu por meio de uma Revisão Sistemática da Literatura, desenvolvida para fornecer informações e identificar estudos relevantes publicados entre o período de 2011 a 2021 nas bases SCOPUS, Web of Science, ACS Publications e Portal de Periódicos CAPES. O tratamento e análise dos artigos coletados foi realizada sob a ótica da análise de conteúdo, por meio da codificação e categorização dos dados analisados. A partir da revisão sistemática, foram coletados 49 artigos selecionados como objeto de pesquisa, por serem relevantes para a pesquisa. Os resultados mostraram que os jogos possuem potencial como uma efetiva ferramenta de aprendizagem, os autores dos trabalhos deram ênfase em como a experiência havia colaborado com o desempenho dos estudantes nas aulas de química, seja para revisar o conteúdo estudado anteriormente, ou combinado com outras técnicas de ensino, ou ainda como uma forma diferente de abordar o conteúdo com o intuito de deixar os alunos mais engajados e motivados com as aulas.
Efecto biofungicida de dos extractos etanólicos a base de pomelo (Citrus × Paradisi) y Tagete (Tagetes erecta L.) con Ruda (Ruta graveolens L.) sobre moho gris (Botrytis cinérea) en condiciones in vitro
Authors: Cifuentes Camila Rozas , Arriagada Álvaro Tapia
Published: January 2023

En vista de la creciente contaminación que genera el uso de pesticidas sintéticos y debido al incremento de la resistencia de fungicidas, ha llevado a desarrollar nuevas alternativas para el control de Botrytis cinérea, un hongo de gran importancia agrícola que genera importantes pérdidas económicas. Uno de estos métodos es el uso de extractos naturales para así generar el menor daño ambiental, además su aplicación constituye una alternativa importante en frutas para consumo fresco. Bajo esta premisa, el objetivo de este trabajo fue determinar la actividad antifúngica in vitro de dos extractos etanólicos de C. Paradisi y T. erecta L. con R. graveolens L. evaluados en medio PDA con tresrepeticiones y cuatro tratamientos, los dos extractos (CR y CP), un controlador biológico antagonista Trichoderma Harzianum (CB), utilizando como testigo el fungicida comercial químico Captan (CQx). Los resultados obtenidos mostraron que las variables a medir: porcentaje de inhibición, antagonismo del controlador biológico y porcentaje de inhibición del crecimiento micelial tienen una eficacia inhibitoria de CR (22,9%) frente a CQx (25,9%) y CP no fue eficiente en el control in vitro de cinérea. Por otra parte, el tipo de antagonismo de Trichoderma Harzianum tampoco fue el esperado para este fitopatógeno.
Prevalência e fatores associados à Síndrome da Fragilidade em idosos de Joinville
Authors: Peres Breno Roberto , Tomaselli Ciro Laerte Beppler , Lobo Pedro Henrique Deeke de Oliveira , Baptista João Pedro Ribeiro , Lima Helbert do Nascimento , Scoralick Francisca Magalhães
Published: January 2023

INTRODUÇÃO: Com o envelhecimento da população Brasileira, dimensionar e avaliar o perfil da população vulnerável a ter a Síndrome da Fragilidade no Idoso (SFI) e entender seus fatores associados é de grande importância. OBJETIVO: Analisar o perfil de idosos que correspondem às informações referentes aos indicadores de fragilidade do questionário de fragilidade de Edmonton, em uma clínica especializada em geriatria. MÉTODO: O presente estudo é do tipo transversal, analítico, com idosos da Unidade especializada de atenção geriátrica em Joinville, Brasil. Foram analisados perfil social econômico (escolaridade, renda, raça, sexo) e a avaliação para a SFI e as comorbidades no idoso. O projeto foi aprovado pelo Comitê de Ética em Pesquisa da UNIVILLE sob parecer de n⁰ 40940020.6.0000.5366. RESULTADO: Os resultados do estudo foram a partir dos 141 idosos entrevistados, com uma média de 74 anos de idade. A maioria (60%) do sexo feminino, de cor branca (90,1%), de baixa escolaridade (56%) e casados ou em união estável (53,2%). A prevalência de algum nível de fragilidade foi de 17,7% (IC95%). DISCUSSÃO: Apesar da discussão sobre os critérios para definição da SFI, o presente estudo baseou-se no questionário de fragilidade de Edmonton - Edmonton Frail Scale. A amostra local da população representa como discussão sobre a escolaridade, tabagismo, renda e o grande número de comorbidades predispõe a SFI e, dessa forma, também uma prevalência maior de queda do idoso. Isso converge com estudos prévios na literatura que ilustram maior prevalência de queda em pacientes com esse perfil epidemiológico. Conclusão: Apesar de algumas limitações do estudo como de ter sido realizado em um serviço de referência em geriatria, o estudo molda o perfil local da população idosa acometida pela SFI.
Characterizing Tseitin-Formulas with Short Regular Resolution Refutations
Authors: De Colnet Alexis , Mengel Stefan
Published: January 2023

Tseitin-formulas are systems of parity constraints whose structure is described by a graph. These formulas have been studied extensively in proof complexity as hard instances in many proof systems. In this paper, we prove that a class of unsatisfiable Tseitin-formulas of bounded degree has regular resolution refutations of polynomial length if and only if the treewidth of all underlying graphs G for that class is in O(log |V (G)|). It follows that unsatisfiable Tseitin-formulas with polynomial length of regular resolution refutations are completely determined by the treewidth of the underlying graphs when these graphs have bounded degree. To prove this, we show that any regular resolution refutation of an unsatisfiable Tseitin-formula with graph G of bounded degree has length 2Ω(tw(G))/|V (G)|, thus essentially matching the known 2O(tw(G))poly(|V (G)|) upper bound. Our proof first connects the length of regular resolution refutations of unsatisfiable Tseitin-formulas to the size of representations of satisfiable Tseitin-formulas in decomposable negation normal form (DNNF). Then we prove that for every graph G of bounded degree, every DNNF-representation of every satisfiable Tseitin-formula with graph G must have size 2Ω(tw(G)) which yields our lower bound for regular resolution.
STRUCTURAL AND THERMAL STABILITY OF FUNCTIONALIZED GRAPHENE INCORPORATED POLYURETHANE NANOCOMPOSITE FOAM
Authors: Yadav Ganesh , Agarwal Kavita , Gupta Sunil Kumar
Published: January 2023

The thermal stability and morphology of polyurethane nanocomposite foams reinforced with chemically modified Fenton graphene (FG), graphene oxide (GO), or reduced graphene oxide (rGO) were investigated. The polyurethane (PU) polymeric nanocomposite foams having 0.5 to 2.0 wt.% were prepared using a thermo-reversible solution method involving a supramolecular self-assembly process. The effect of edge and surface oxidization morphology of functionalized graphene/PU foams was characterized by scanning electron microscopy and X-ray diffraction methods. The thermal stability of the polyurethane nanocomposite foam was investigated by thermo-gravimetric analysis (TGA). The thermal stability of 0.5 wt.% FG-based nanocomposite foam was more as compared to 0.5 wt.% of GO and rGO-based nanocomposite foam.
Impacts of reference strain rate and strain level dependency on rate effects in fine-grained soils
Authors: Robinson S. , Brown M. J. , Knappett J. , Brennan A.
Published: January 2023

Viscous rate effects in fine-grained soils may occur in many engineering applications (e.g. dynamically penetrated anchors, sampling, rapid load testing of piles or high-speed soil characterisation), where high strain rates are induced during shear. Often it is difficult to correct for this enhancement of soil strength as fundamental understanding and quantification of rate effects is an area where further research is required. This is at least in part due to limitations of soil characterisation equipment and instrumentation. With the aim of tackling some of these issues a high-speed triaxial testing system was developed incorporating lubricated end platens, which was used to test kaolin at strain rates from 0·1 to 180 000%/h. This allowed observation of behaviour from fully drained, partially drained and undrained conditions, through to viscous effects. Results were used to investigate how rate effects are influenced by strain and consolidation level and how rate normalisation parameters are affected. This was then used to improve a commonly adopted rate characterisation approach such that it performed better across a wider range of strain rates and can be used for more consistent evaluation of rate effects between studies.
A Study on the Impact of COVID-19 on Korea’s Exports in the Pharmaceutical Industry: Comparison between OECD and Non-OECD Countries
Authors:   The Korea International Trade Research Institute, Kim Hyo-Jin , Shim Kieun , Jeong Kyong-Hwa
Published: January 2023

Purpose – This paper empirically analyzes the impact of the COVID-19 pandemic on Korea’s exports in the pharmaceutical industry, and this estimation result is compared with that of manufacturing. Moreover, to distinguish those impacts between OECD and non-OECD countries, we divide 76 countries into two groups, OECD and non-OECD countries, and compare the estimation results. Design/Methodology/Approach – We used the panel data of 76 countries and quarterly periods from the first quarter of 2020 to last quarter of 2021 for estimation. The econometric technique employed in the study is PPML (Poisson pseudo maximum likelihood). Findings – We show that the COVID-19 pandemic has positively influenced Korea’s exports in the pharmaceutical industry. Moreover, the impact turns out to be statistically more significant in non-OECD countries than OECD countries. The supplementary finding of our study is that there is no clear evidence on the linkage between COVID-19 and Korea’s exports in the manufacturing sector. Research Implications – Unlike existing papers have focused on showing the negative relationship between COVID-19 and international trade, this paper has showed the positive linkage between them.
The Effect of the Background Factors of Trade Negotiation and Negotiation Strategy on Non-Face-to-Face Negotiation Outcomes of Korean Small and Medium-Sized Trading Companies
Authors:   The Korea International Trade Research Institute, Lee Shin-Kyuo
Published: January 2023

Purpose – The purpose of this study is to analyze the relationship between background factors of business negotiation and negotiation outcome for Korean small and medium sized trading companies. Design/Methodology/Approach - By analyzing business negotiation factors such as culture, organization, knowledge on trade practice, individual characteristics, and negotiation process, a research model was derived, and research hypotheses were verified. Findings - The results of this study are as follows. Cross-cultural awareness, organizational support, trade practice knowledge, and individual characteristics had positive direct effects on negotiation outcomes, and negotiation outcomes also had a positive effect on negotiation profit, while cooperative negotiation strategy did not have a significant effect on negotiation outcomes. Research Implication - International trading companies increasingly rely on international trade negotiations for survival and growth. It was found that factors such as cultural difference, organizational support, individual characteristics, and cooperative strategy are important factors affecting positive negotiation outcomes. Therefore, it is essential that negotiators in small and medium trading companies need to understand the cultural differences of their counterparts, and the organization needs to provide direct support to negotiators. Based on the results of this study, strategic alternatives were suggested for trade negotiators to conduct efficient trade negotiations.
An Analysis of Structural Relationships among the Factors Affecting Financial Performance
Authors:   The Korea International Trade Research Institute, Kim Mi-Hui
Published: January 2023

Purpose – This study aims to examine structural relationships among factors affecting financial performance. Design/Methodology/Approach – Data were obtained from 136 statistically reliable Annual Balance Sheets (2019) submitted to the National Tax Service and ALIO by tertiary and general hospitals. Liquidity indicator, leverage ratio, turnover indicator, growth indicator, and profitability indicator were calculated based on various account statistics on the financial statements. SPSS 26 was used to examine frequency according to general characteristics, and AMOS 28 was used to analyze structural relationships among factors affecting financial performance. Findings – As a result of the analysis of structural relationships, liquidity and growth have a significant positive (+) effect on profitability. Liquidity has a partial mediating effect and a full mediating effect, respectively, in that growth and activity have a significant positive (+) effect on profitability. Research Implications – Profits are generated when a stable financial position is premised, and synergy effects are also exerted on activity and growth performance. Therefore, hospitals must maintain a stable financial position based on liquidity to provide high-quality public health services by increasing profits and improving efficiency. In addition, since the three major cost variables function as factors of financial performance, it is necessary to conduct a comprehensive analysis in future research by adding cost variables based on three-year time series data.
A Study on Developing the REEIDI (Rare Earth Element Import Diversification Index)
Authors:   The Korea International Trade Research Institute, Maeng Cheol-Kyu
Published: January 2023

Purpose – This paper focuses on developing the Rare Earth Element Import Diversification Index (REEIDI) to monitor the sustainability of the rare earth elements’ import volume in the Korean domestic market and industry. Design/Methodology/Approach – The data used in this paper is the import volume of REEs from trading partners in the form of kilograms and US dollars by the Korea Customs Services monthly from 2011 to 2021. The REEIDI is calculated from the inverse formula of the Herfindahl-Hirschman Index, which shows the diversification level of Korea’s REE imports. Findings – The REEIDI enhanced from 1.850 in 2011 to 2.656 in 2021. During the period from 2011 to 2021, the price of the imported REEs and REEIDI showed an inverse relationship. It is empirically proved that REEIDI explains the changes in the REE price. Research Implications – With the development of REEIDI, the sustainability of REE imports can be monitored on a regular basis. Through this paper, it is implied that the REEIDI could reflect the changes in the import price of REEs to the Korean domestic market.
Relationship Between Emissions Trading Scheme and the Cost of Debt: Focusing on Export Concentration
Authors:   The Korea International Trade Research Institute, Kim Sun-Hwa , Jung Yong-Ki
Published: January 2023

Purpose – This study verifies whether the effect of ETS (Emissions Trading Scheme) on debt financing costs is differentiated according to export concentration, Also, this study verifies whether the increase and decrease effects of debt financing costs according to the characteristics of ETS companies are differentiated according to export concentration. Design/Methodology/Approach – This study analyzes companies listed on the Korean Stock Exchange (KSE), and the analysis period was from 2015 to 2020 as the emission trading scheme started in 2015. The sample taken for this study includes 3,504 firm-year observations. Findings - The results of the analysis are as follows. First, in companies with no exports and companies with a low proportion of exports, debt financing costs are reduced due to the ETS. Second, when carbon intensity is high in a company with high export concentration, the increase in debt financing costs increases. Third, companies with no exports and companies with high export concentration show a decrease in debt financing costs. It can be seen that creditors are differentially aware of the effect of the ETS according to the degree of export concentration, and consider the degree of export concentration even when considering the characteristics of companies responding to the ETS. Research Implications – The results of this study will be helpful for corporate strategies and government support policies for ETS firms. In addition, it will provide practical implications for capital market participants that evaluate climate-related risks.
Current status in the copper ore processing (review)
Authors: Aleksandrova T. N. , Orlova A. V. , Taranov V. A.
Published: January 2023

The article provides the analysis of process flows used for sulfide and oxidized copper ore treatment, reagent schemes, process equipment, indicators of flotation concentration at a number of domestic and foreign concentrating mills and plants. Autogenous and semi-autogenous grinding mills are widely used at the ore preparatory processing at the first stage of grinding to eliminate medium and fine crushing stages. An alternative is the use of high pressure grinding rolls that can reduce electricity consumption as compared to autogenous and semi-autogenous grinding. There is an increase in the use of large-volume and high-performance ore-preparation and flotation equipment for maintaining the quality and quantity of the product. In addition to ball mills, fine and ultrafine regrinding mills of various configurations are widely used at the stage of rougher flotation concentrate regrinding. The analysis of flotation reagents used to improve separation process efficiency was conducted with domestic and foreign approaches to flotation reagent selection shown. It is noted that foreign concentrating mills often use a combination of main and additional collectors. The paper provides the data on flotation reagents used in the copper sulfide and oxidized ore concentration, and their consumption. A combined diagram of flotation-hydrometallurgical processing of mixed copper ore from the Udokan deposit is considered. Conclusions are drawn about current trends in the processing of copper ores including the choice of equipment.
Structure formation and processability of the Al—Zn—Mg—Ca—Fe—Zr—Sc alloy at hot rolling and TIG welding
Authors: Karpova Zh. A. , Shurkin P. K. , Sivtsov K. I. , Laptev I. N.
Published: January 2023

Process conditions are suggested for manufacturing wrought semi-finished products (2 and 1 mm sheets) from the Al-4.5%Zn-2.5%Mg-2.5%Ca-0.5%Fe-0.2%Zr-0.1%Sc experimental alloy including thermomechanical processing at t = 400450 °С and reduction ratios up to 98 %, as well as softening annealing of the sheet metal at t = 350400 °C for 1—2 hours. It was found that the as-cast structure consists of eutectic phases (Al, Zn)4Ca, Al10CaFe2 5 to 25 gm in size, and a Al2Mg5Zn5 nonequilibrium T-phase located along the boundaries of dendritic cells (Al). Zirconium and scandium form a solid solution with aluminum as a result of solidification. After hot rolling, the structure of 2 mm sheets consists of lineage-oriented discrete intermetallic particles and their conglomerates up to 40 gm in size in the (Al) matrix. The structure of 1 mm sheets features by greater fineness and structure uniformity. The fine structure of deformed semi-finished products was analyzed using transmission electron microscopy (TEM), and this analysis showed that nanoparticles in the Al3(Zr, Sc) phase of the L12 structural type are maximum 20 nm in cross-section. The following level of mechanical properties was achieved in wrought semi-finished products: ultimate strength σв ~ 310330 MPa, yield strength σ0,2 ~ 250280 MPa with relative elongation δ ~ 4.57.0 %. The possibility of TIG welding using standard AMg5 wire as a filler material was studied. It was shown that the new alloy demonstrated no tendency to form hot cracks. According to the results of X-ray tomography, the percentage of porosity in the weld was 1.27 vol.%. The prevalent pore diameter did not exceed 0.2 mm. In general, the resulting structural and qualitative parameters of weld joints contribute to obtaining a strength of 75 % of the strength index of the initial wrought semi-finished products (sheets) achieved by stabilizing annealing at t = 350 °С for 3 hours.
Kinetics of sulfuric acid leaching of nickel from grinding waste of rhenium-containing superalloys
Authors: Таrganov I. E. , Troshkina I. D.
Published: January 2023

The paper studies the kinetics of sulfuric acid leaching of nickel, the main component of grinding waste of ZhS-32VI rheniumcontaining heat-resistant superalloy formed during mechanical processing of products and containing such impurities as abrasive materials, oils, ceramics and other contaminants with refractory metal concentration in a solid residue, in agitation mode. The nickel content is 60 %. In addition to nickel, grinding waste contains other metals such as rhenium, chromium, cobalt, tungsten, tantalum, molybdenum, hafnium, titanium, and aluminum. The process of nickel leaching from waste with a sulfuric acid solution was carried out in a thermostated cell at an elevated temperature (55–85 °С), waste : 3 M H2SO4 solution phase ratio of 1 g : 10 ml, and stirring rate of 200 min–1. Kinetics was studied using a fraction of –0.071 mm with the highest yield (49.2 wt.%) in grinding waste. Convex kinetic curves of nickel leaching from waste were obtained. It was found that when the temperature changes from 55 to 85 °С, the time until leaching stops decreases from 220 to 140 min, and nickel recovery from the solution increases from 45 to 99 %. The data of the obtained kinetic curves were linearized according to the «contracting sphere» equation, Gistling–Braunstein and Kazeev–Erofeev equations (the latter is most suitable for description). Taking into account the assessment of anamorphosis correlation coefficients, it was found that nickel leaching from grinding waste is limited by the chemical reaction, and the process proceeds in the kinetic region of the reaction. The apparent activation energy calculated using the Arrhenius equation and rate constants obtained by processing linearized kinetic curves according to the «contracting sphere» model, was 47.5±0.5 kJ/mol. This value confirms the course of the process in the kinetic region where the process can be intensified by increasing its temperature.
In memory of Professor Alexander Sergeevich Medvedev
Authors: Editorial Article
Published: January 2023

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Extraction of non-ferrous metals and arsenic from fine dusts of copper smelter production by combined technology
Authors: Mamyachenkov S. V. , Khanzhin N. A. , Anisimova O. S. , Karimov K. A.
Published: January 2023

Fine dusts of copper smelting production are a valuable raw material for the extraction of heavy non-ferrous, noble and rare metals. A feature of dusts is the high content of arsenic in them, which must be removed from the production cycle in the form of a product suitable for safe storage. The most rational way is the combined technology for processing copper smelting production dusts including low-temperature dust roasting (calcination) in order to distill arsenic into a separate product and to break up poorly soluble sulfide and ferrite zinc and copper compounds. The chemical and phase composition of Ausmelt technology dusts is presented. Thermodynamic calculations of reactions occurring during the dust roasting were carried out in order to study the behavior of copper, zinc, arsenic and iron compounds when roasted in the temperature range of 20–1000 °C, features of solid phase formation and composition, optimization of arsenic roasting and distillation conditions. It was established that dust calcination allows the conversion of poorly soluble sulfides and ferrites of zinc and copper into acidsoluble oxides and sulfates. Thermodynamic parameters were determined for the sulfuric acid leaching of individual cinder compounds. The results of laboratory studies showed that the calcination temperature of 550 °C provides the most satisfactory results of arsenic conversion to sublimates (more than 95 %) as well as copper and zinc recovery into the solution during sulfuric acid leaching (more than 90 %). The initial acidity of solutions of 50 g/dm3 and solution temperature of 60°C are sufficient to achieve high values of copper and zinc recovery into the solution.
Influence of high-temperature treatment conditions on the structure and tribological properties of a nickel-based laser clad coating
Authors: Soboleva N. N. , Makarov A. V.
Published: January 2023

Laser cladding featuring by a minimal thermal impact on the substrate is an advanced method of restoring the working dimensions of parts operated under wear conditions. Ni–Cr–B–Si system coatings can be used in parts operated at high temperatures. The research was aimed to study the influence of heating and subsequent cooling conditions during high-temperature treatment on the structural phase state formation features of the coating obtained by PG-SR2 powder laser cladding (chemical composition, wt.%: 14.8Cr; 2.1B; 2.9Si; 2.6Fe; 0.48C; the rest is Ni), and properties achieved in this process (hardness and tribological properties when sliding on the fixed corundum abrasive). Samples with the clad layer were heated at 1050 °С (holding for 1 h) with subsequent cooling in water (which made it possible to record structural transformations under high-temperature heating), in air, in a muffle furnace and in a vacuum furnace. It was shown that the cooling rate during the high-temperature treatment of the laser clad PG-SR2 coating has a significant effect on the formed structure and properties. High-temperature heating leads to a partial diffusive dissolution of Ni3B nickel borides and Cr23C6 chromium carbides in a solid solution and a corresponding decrease in hardness, an increase in abrasive wear intensity and friction coefficient. Cooling rate deceleration from 1050 °C when samples are cooled in air, muffle and vacuum furnaces leads to the release of CrB chromium borides and Ni3Si nickel silicides that were absent in the clad coating structure. High-strength CrB borides with hardness equal to or even higher than that of the corundum abrasive limit the development of the microcutting mechanism during abrasive wear. Large chromium carbides and borides formed during slow cooling in the furnace form wear-resistant frame-like structures. This leads to an increase in hardness and abrasive wear resistance to levels that exceed the features of the original clad coating.
Viscosity of conventional cryolite-alumina melts
Authors: Rudenko A. V. , Kataev A. A. , Tkacheva O. Yu. , Zaykov Yu. P. , Pyanykh A. A. , Arkhipov G. V.
Published: January 2023

The study covers the viscosity of NaF–AlF3–CaF2–Al2O3 conventional cryolite-alumina melts with a cryolite ratio CR = 2.3 depending on the CaF2, Al2O3 content and temperature. The viscosity of cryolite-alumina electrolyte samples prepared under laboratory conditions and electrolyte samples of industrial electrolytic cells was measured by the rotary method using the FRS 1600 rheometer («Anton Paar», Austria). The laminar flow region of the melt determined according to the dependence of viscosity on shear rate at a constant temperature was 10–15 s–1 for all the studied samples. The temperature dependence of cryolite-alumina melt viscosity was measured at a shear rate of 12 ± 1 s–1 in the temperature range from liquidus to 1020 °C. It was shown that the change in the viscosity of all samples in the investigated temperature range (50–80 °С) can be described by a linear equation. The average temperature coefficient of linear equations describing the viscosity of cryolite-alumina electrolytes prepared in laboratory conditions was 0.005 mPа· s/°С, which is 2 times less compared to industrial cell electrolytes. Thus, the change in the viscosity of industrial cell electrolytes with increasing temperature is more significant. Both alumina and calcium fluoride additives increase the cryolite melt viscosity. The viscosity of samples prepared with the conventional composition NaF–AlF3–5%CaF2–4%Al2O3 (CR = 2.3) is equal to 3.11 ± 0.04 mPа· s at an electrolysis operating temperature of 960 °C, while the viscosity of industrial cell electrolytes with the same cryolite ratio is 10–15 % higher and falls in the range of 3.0–3.7 mPа· s depending on the electrolyte composition.
Influence of parameters used for melt processing by nanosecond electromagnetic pulses on the structure formation of cast aluminum matrix composites
Authors: Deev V. B. , Ri E. Kh. , Prusov E. S. , Ermakov M. A. , Kim E. D.
Published: January 2023

The paper focuses on establishing the effect of nanosecond electromagnetic pulses (NEPs) with different amplitudes on the formation of the structure of cast aluminum matrix composites of the Al–Mg2Si pseudobinary system with hypoeutectic (5 wt. % Mg2Si) and hypereutectic (15 wt. % Mg2Si) compositions. As the NEP generator amplitude in composites containing 5 and 15 wt. % Mg2Si increases, the matrix alloy structural components (α-solid solution and eutectic) are refined, while no significant differences in the sizes and morphology of Mg2Si primary crystals were observed in the hypereutectic range of compositions. Presumably, the observed nature of the NEP effect on the structure of composites in the hypereutectic region of compositions is associated with the features of their crystallization behavior. The temperature range of the L + Mg2Si two-phase region presence is much lower than NEP irradiation temperatures. Apparently, this is the reason why NEPs have no effect on the thermodynamic state of Mg2Si primary crystal/melt interfaces. It was shown that a promising option for the simultaneous modifying effect on all structural components of Al–Mg2Si aluminum matrix composites (solid solution, eutectic, Mg2Si primary particles) is a combination of thermal-rate treatment and irradiation of melts by NEPs, as well as additional melt processing by NEPs during crystallization.
Structure and properties of AL–Cu–Yb alloy with iron and silicon impurities
Authors: Barkov M. V. , Mamzurina O. I. , Glavatskikh M. V. , Barkov R. Yu. , Pozdniakov A. V.
Published: January 2023

The effect of iron and silicon impurities on the phase composition and properties of the Al–4.3Cu–2.2Yb quasi-binary alloy was determined. In addition to the aluminum solid solution and dispersed eutectic ((Al) + Al8Cu4Yb) containing about 1 % of dissolved iron, Al3 Yb/(Al,Cu)17Yb2 and Al80Yb5Cu6 Si8 phases were identified in the cast alloy microstructure (the latter was not found in an alloy of a similar composition but without impurities). After homogenization annealing at t = 590 °C for 3 h, the structure is represented by compact fragmented and coagulated intermetallic compounds 1–2 μm in size, and a solid solution (Al) with a maximum copper content of 2.1 %. The hardness of deformed sheets significantly decreases after 30 min of annealing, and then changes slightly in the following 5.5 h of annealing at t = 150÷210 °C. After annealing at 180 °C (τ = 3 h), a substructure with a subgrain size of 200–400 nm is formed in the alloy structure. Rolled sheet softening occurs due to recovery and polygonization processes after annealing at temperatures up to 250 °C, and due to recrystallization after annealing at temperature above 300 °C. After annealing at 300 °C (τ = 1 h), the recrystallized grain size is 7 μm. The grain increases to 16 μm after annealing at t = 550 °C (τ = 1 h). The alloy under study has a high level of mechanical properties (conditional yield limit is 205–273 MPa, tensile strength is 215–302 MPa, relative elongation is 2.3–5.6 %) in the annealed state after rolling. Iron and silicon impurities do not lead to the formation of coarse lamellar intermetallic phases and do not reduce the ductility of the investigated alloy.
Using reagents in the form of inverse microemulsion for lead and zinc sulfide flotation
Authors: Bragin V. I. , Usmanova N. F. , Burdakova E. A. , Kondratieva A. A.
Published: January 2023

The paper presents the results of studies on the use of collecting agents in the form of an inverse microemulsion (IМE) of the «water in oil» type (i.e. suspended water droplets are in the oil phase) for the flotation extraction of lead and zinc minerals. Lead and zinc concentrates, lead-zinc ore were used as initial samples for flotation. The content of galena in the lead concentrate was 74.7 %, and the content of sphalerite in zinc was 78.7 %. Basic collecting agents in the IМE composition were potassium butyl xanthate (PBX) and kerosene. A nonionic surfactant (NSA) was used for IМE stabilization. Casein was used as additives to main reagents to remove the negative effect of osmotic pressure during the IМE preparation. Casein was transformed into the active soluble form using sodium sulfide. The particle size in the inverse microemulsion was 12.38 nm. In flotation tests, the following options for feeding reagents to the flotation pulp were studied: IМE, IМE + frother, potassium butyl xanthate + frother. The T-92 reagent was used as a frother. PBX consumption as part of IME and in the traditional feeding was 26 g/ton. The results of laboratory tests showed that the method of feeding flotation reagents in the form of IМE leads to both an increase in the flotation rate of lead and zinc sulfides and an increase in their recovery into a foam product. In addition to the increased flotation speed, tests with the use of IМE in the bulk lead-zinc ore flotation cycle showed an increase in extraction into the ultimate concentrate by 10.8 % for lead, by 38.5 % for zinc, in comparison with the traditional feeding of reagents (collector + frother). An increased selectivity of the IМE effect in relation to zinc sulfides, in comparison with lead sulfides, was noted. The flotation rate coefficient of sphalerite is 7.8 times greater than that of galena. An increase in extraction into the ultimate zinc concentrate is also higher and amounted to 16.78 %, while for the lead concentrate it is 1.9 % under the same conditions.
Distillation recovery of tellurium from copper telluride in oxide forms
Authors: Nitsenko A. V. , Volodin V. N. , Linnik X. A. , Tuleutay F. Kh. , Burabaeva N. M.
Published: January 2023

The paper presents the results of studies into tellurium extraction from its compounds with copper in the form of oxides by the pyrometallurgical method. Commercial copper telluride of Kazakhmys Corporation LLP containing crystalline phases, wt.%: Cu7Te4 – 36.5; Cu5Te3 – 28.5; Cu2Te – 12.9; Cu2.5SO4(OH)3·2H2O – 16.2 and Cu3(SO4)(OH)4 – 6.0 was used as an object of research. The physical and chemical research and technology experiments showed the fundamental possibility of commercial copper telluride processing by oxidative distillation roasting with the extraction of tellurium into a separate product. Air oxygen was used as an oxidant. It was established that a pressure decrease in the range of 80–0.67 kPa at the same temperature entails an increase in the degree of tellurium extraction. However, the tellurium extraction degree (93.0–98.0 %) at all pressures (within 1 hour) acceptable from the technology point of view is achieved at 1100 °C. Increasing the exposure to 3 hours has a minor beneficial effect. Diffractometric studies of cinders from technology experiments showed a decrease in the content of copper oxides in the pressure range of 80–40 kPa and an increase in the Cu3TeO6 phase content. With a subsequent increase in rarefaction from 40 to 0.67 kPa, there is a noticeable decrease in the amount of cuprite and, as a consequence, a sharp increase in the amount of cuprous oxide. A slowdown in the increase of the copper tellurate volume was noted at pressures of 40–20 kPa, and a sharp drop in its content at pressures below 13.3 kPa. The derived condensate is a free-flowing mixture of crystalline phases of tellurium dioxide (67.7 %) and tellurium oxysulfate (32.3 %). This condensate is a middling product for further production of elemental tellurium.
Sergei Vladimirovich Mamyachenkov is 60 years old
Authors: Editorial Article
Published: January 2023

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Dependence of morphology, structure, composition and biocompatibility of Ca- and P-doped TiO 2 coatings on PEO process parameters
Authors: Ponomarev V. A. , Kuptsov K. A. , Sheveyko A. N. , Shtansky D. V.
Published: January 2023

The study covers the influence of bipolar pulsed regime parameters of titanium plasma electrolytic oxidation (PEO): voltage (U), pulse duration (t) and pause duration between pulses on the structure and morphology of TiO2 coatings doped with Ca and P. Threshold values of voltage (U1) and positive pulse duration (t1), which led to pore-free coating formation, were determined. It was shown that an increase in U1 leads to an increase in pore size and Ca and P concentration in the TiO2 coating. A relationship between rutile content in the coating and Ca and P concentrations was identified. It was found that the size and distribution of pores depend ont1. A structure with fine pores evenly distributed over the sample area is formed during a short positive pulse. An increase in t1 leads to the formation of a structure with unevenly distributed large pores. An increase in the values of U2 and t2 leads to a decrease in Ca and P concentrations and rutile content in the coating. It was shown that the surface of PEO TiO2 coatings ensures the growth of crystallites of (Ca, P)-containing phases when kept in a simulated body fluid solution. It was found that the amount of an apatite-like layer depends on the content of Ca and P in the TiO2 layer, as well as the size and distribution of pores.
Formation of carbon nanotubes and microsilica when obtaining crystalline silicon in three-phase electric ore smelting furnaces
Authors: Kuz’min M. P. , Kondratiev V. V. , Kuz’mina A. S. , Burdonov A. E. , Ran Jia Q.
Published: January 2023

The volume of silicon waste generated annually in the Irkutsk Region is 20 thousand tons per year, and the volume of waste accumulated in three sludge fields of JSC «Silicon» exceeds 3 million m3. The main type of crystalline silicon production waste is dust from gas cleaning systems of electric ore smelting furnaces. In this regard, this paper studies its chemical composition and the possibilities of using valuable components (amorphous silica, carbon nanotubes (CNT)) included in its composition. The study demonstrates that it is possible to separate this product by flotation into 3 components — sand fraction, flotation tailings enriched in SiO2, and froth enriched in carbon in the form of CNT. The structure of carbon nanotubes was studied and their physical and mechanical properties were determined: elastic modulus (2000 GPa), tensile strength (75 GPa), and thermal conductivity (4000 W/(m·K)). The amount of heat required to obtain 1 kg of CNT in electric ore smelting furnaces was calculated. Based on the material balance of commercial silicon electric smelting, it was found that 153 kg of CNT and 336 kg of flotation tailings are formed per ton of crystalline silicon during the endothermic process. Flotation tailings consist of 75 % amorphous microsilica particles. According to heat effect and Gibbs energy calculations made for amorphous microsilica formation reactions, it was found that all processes are exothermic, and the process of solid silicon carbide particles (2SiC + 3O2 → 2SiO2 + 2CO) oxidation with air oxygen has the highest thermodynamic probability. The economic efficiency of using amorphous silica to produce casting silumins was calculated, and its results clearly demonstrate a quick payback period (6 months), as well as a high level of its profitability (USD 819672).
SHS compaction of TiC cermets using mechanically activated mixtures
Authors: Bogatov Yu. V. , Shcherbakov V. A.
Published: January 2023

This paper focuses on obtaining cermet composite materials by SHS compaction. The study covers the effect of mechanical activation of metal components contained in reaction mixtures based on the Ti + C + Cr + Ni system when treated with grinding media in a ball mill. Two mechanical activation methods were used for Ti, Cr and Ni metal powders. In the first method, Cr and Ni powders were activated with grinding media separately from other reaction mixture components, and then mixed with titanium and carbon black powders. It is shown that the preliminary mechanical activation of inert components reduces the temperature and rate of combustion and increases the average size of carbide grains. In the second method, Ti + + Cr, Ti + Ni, and Ti + Cr + Ni powder mixtures were jointly processed in a ball mill, and then mixed with carbon black. This method provided mechanical activation of titanium particles with a minimum effect of grinding media on Cr and Ni powders. This led to an increase in the combustion rate and temperature, a decrease in the average size of carbide grains, and an increase in the composite structure homogeneity. A mechanism is proposed for the interaction of reagents (Ti + C) with the participation of activated Cr and Ni particles in combustion and structure formation zones, according to which the mechanical activation of inert components leads to their direct participation in the reaction interaction of titanium with carbon, which determines a decrease in the combustion rate and temperature and affects the fineness and structural homogeneity of compact composites. The results obtained were used to increase the structural homogeneity and fineness of the STIM-3B composite (Grade 3B synthetic hard tool material).