Navegando por Assunto "Glass"

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Acesso aberto (Open Access)
Confecção de discos de desbaste a partir de AI2O3 e pó de vidro
(Universidade Federal do Pará, 2009) OLIVEIRA, Rosane Felice de; DIAS, Carmen Gilda Barroso Tavares; http://lattes.cnpq.br/2113791118142177
This article describes the development of abrasive and cutting disks made of alumina and waste glass powder to apply in cutting tools. These disk mills are used to micromize rigid post-consumed thermoplastics and let its use in a lot of recycling process, as rotomolding. This cutting disk uses glass powder as a fluxing agent and poly(ethylene terephthalate) post-consumed to give a plastic behavior to the powder, making it easier to fill in the mold. The amounts of glass powder were analyzed from previous studies with different minerals, as diopside and feldspar, since the studies with waste glass powder substituting natural minerals are recent. The development of the disks occurs in two steps. The first one is the homogeneization of the compounds with the calculated amounts. Afterwards it's pressed and taken to the mufla to get the percolation of the resin and its complete degradation up to a temperature of 900oC, pre-sintering and soften the silicates. After getting these green composites, it happens the second and final step, when the disks are sintered to decrease the porosity and improve its strength, followed by a superficial finish and cutting tests.
Acesso aberto (Open Access)
Estudo de rotas tecnológicas para a síntese de geopolímeros com adição de micropartículas de vidro: análise da influência do tamanho e forma das partículas
(Universidade Federal do Pará, 2025-02-14) MODESTO, Alex da Silva; SILVA, Alisson Clay Rios da; http://lattes.cnpq.br/7389345867032737; https://orcid.org/0000-0001-9186-2287
The sustainable construction of the future requires materials that consume less energy, emit fewer greenhouse gases and reuse waste that is harmful to the environment, such as discarded glass, one of the main waste products in the production chain. This research developed geopolymers, inorganic polymers formed by the activation of amorphous aluminosilicates in an alkaline medium, using me-takaolin and blast furnace slag as precursors and recycled glass microparticles as an additive. Com-positions were formulated with glass contents ranging from 0% to 60%, in particle size ranges of < 38 μm, 38-45 μm, 45-75 μm and 75-180 μm, and alkaline hydroxide and sodium silicate activators. Compression tests carried out on cylindrical specimens after 7 days of curing revealed that the addi-tion of 40% glass with a grain size of 38-45 μm resulted in an 80% increase in compressive strength compared to the unmodified material, reaching values of over 40 MPa. Microstructural analysis by SEM and EDS confirmed greater density and reduced porosity in the geopolymer matrix. Tensile adhesion tests also indicated the viability of the material as a substrate for coatings, meeting the demands of the construction industry. It is concluded that geopolymers with added recycled glass combine high mechanical performance and sustainability, promoting circular economy and repre-senting a viable alternative to the use of Portland cement.
Acesso aberto (Open Access)
O vidro e os vitrais de edificações históricas de Belém: patologias e conservação
(Universidade Federal do Pará, 2013-09-05) PINTO, Amanda Monteiro Corrêa; SANJAD, Thais Alessandra Bastos Caminha; http://lattes.cnpq.br/8950586647715771
The application of glass in Belém’s architecture, at first, was restricted to large buildings, in the late XIXth century, reaching its peak only in the next century, during the eclectic movement, as an import issue. However, face to the overexposure to the weather and improper substitutions, ancient glasses are gradually disappearing, almost being impossible to documentate it properly. In order to safeguard this material, the main objective of this research is to investigate technologically glasses and stained-glasses physico-chemical characteristics from buildings of Belém and its damages caused by weather conditions. Selected samples were characterized through optical microscopy, and scanning electron microscopy with energy dispersive X-ray microanalysis (SEM/EDX), concomitantly with the execution of graphic in order to do damage diagnosis and to identify most frequent pathologies. Therewith it was possible to verify that samples present a moderated level of degradation as considerable deposits of soot and discoloration and that the biofilm which develops at the glass surface is responsible for its opacity, that fact origins moderate corrosion and stains. FRX data revealed that all samples as soda-lime glass with 70% of SiO2. Resulting data will be important to subsidize conservation and restoration practices on historical glasses and stained-glasses according to local weather conditions.