Search results for: Annelise Kopp Alvesa

Authors: Henrique Gomes dos Santosa, Manoel Henrique Alvesa, Jane Zoppas Ferreiraa, Annelise Kopp Alvesa

Abstract:

This work aimed to seek an environmentally sustainable surface coating alternative by researching the influence of the addition of graphene oxide (GO) and carbon nanotubes (CNT) on the silanization of coatings to increase the wear resistance in galvanized steel, using the pin-on-disk test. The results obtained were compared between different concentrations of additives and the number of coating layers, in addition to comparing with samples without coating and only with silane layers. Bis-1,2-(triethoxysilyl)ethane (BTSE) silane was used in silanizing the coatings with CNT or GO and applied to the samples through dip-coating to form one, four, or eight layers. The wear test results found that three samples stood out in relation to the objective, showing an increase in wear resistance compared to the galvanized sample only. The rolling effect and the lubricity character presented by carbon nanotubes were positive for the increase in wear resistance obtained. The reduction in wear compared to the galvanized-only sample reached 82%. Raman spectroscopy was also carried out to detect the presence of silane, GO, and CNT, in addition to roughness tests and SEM to assess the homogeneity of the coating. The carbonaceous additives, graphene oxide, and carbon nanotubes in certain amounts of layers and specific concentrations fulfilled their objective against the wear imposed on the substrate.

Keywords: silane, coating, graphene oxide, carbon nanotubes, wear resistance

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Authors: Mestawot Beyene Tafese, Erika Kopp

Abstract:

Sustainable development, aimed at meeting current needs while safeguarding the needs of future generations, is a global imperative. Higher education stands as a pivotal force in fostering sustainable values and behaviors. However, most scholars and governments primarily focus on environmental and economic aspects. Consequently, this study examines the distribution patterns of higher education for social sustainability. The study highlights overall annual scientific production trends, leading journals and countries in scientific publication, most researched topics, and frequently used keywords. The study utilized a bibliometric method with the aid of the R Studio program. The analysis reveals Sustainability (Switzerland) as the leading journal, with 292 articles published, followed by the International Journal of Sustainability in Higher Education, which published 186 articles. Additionally, the USA is identified as the leading country, with Spain ranking second in producing research related to higher education for socially sustainable development. Among the 54 African countries, only South Africa ranks 13th, contributing fifty-nine scientific articles. Furthermore, higher education for sustainability, sustainable education, sustainable development goals, etc., emerge as the most researched topics, while the term "higher education" is prevalent in 29% and "sustainability" in 28% of the documents. Notably, according to the analysis, social sustainability is the focus of only 3% of articles. This suggests that academics researching sustainable development and higher education have overlooked social sustainability, a crucial human component of sustainable development. Consequently, the researchers concluded that social academics who are interested in studying sustainable development and higher education should give priority to social sustainability.

Keywords: higher education, bibliometric analysis, social sustainability, sustainable development

Procedia PDF Downloads 60

Authors: Daniel Osorio, Andreas Klenk, Stefan Weihe, Andreas Kopp, Frank Rödiger

Abstract:

Future power plants currently face high design requirements due to worsening climate change and environmental restrictions, which demand high operational flexibility, superior thermal performance, minimal emissions, and higher cyclic capability. The aim of the paper is, therefore, to investigate the creep and thermo-mechanical material behavior of improved materials experimentally and welded joints at component scale under near-to-service operating conditions, which are promising for application in highly efficient and flexible future power plants. These materials promise an increase in flexibility and a reduction in manufacturing costs by providing enhanced creep strength and, therefore, the possibility for wall thickness reduction. At the temperature range between 550°C and 625°C, the investigation focuses on the in-phase thermo-mechanical fatigue behavior of dissimilar welded joints of conventional materials (ferritic and martensitic material T24 and T92) to nickel-based alloys (A617B and HR6W) by means of membrane test panels. The temperature and external load are varied in phase during the test, while the internal pressure remains constant. At the temperature range between 650°C and 750°C, it focuses on the creep behavior under multiaxial stress loading of similar and dissimilar welded joints of high temperature resistant nickel-based alloys (A740H, A617B, and HR6W) by means of a thick-walled-component test. In this case, the temperature, the external axial load, and the internal pressure remain constant during testing. Numerical simulations are used for the estimation of the axial component load in order to induce a meaningful damage evolution without causing a total component failure. Metallographic investigations after testing will provide support for understanding the damage mechanism and the influence of the thermo-mechanical load and multiaxiality on the microstructure change and on the creep and TMF- strength.

Keywords: creep, creep-fatigue, component behaviour, weld joints, high temperature material behaviour, nickel-alloys, high temperature resistant steels

Procedia PDF Downloads 116