RESUMO Atualmente, os resíduos da indústria de cerâmica vermelha apresentam-se como uma alternativa em potencial para uso em matrizes cimentícias como adição mineral ou pozolana de baixa reatividade. Este estudo, teve como objetivo avaliar a influência da substituição parcial do cimento CP V ARI por resíduo da indústria de cerâmica vermelha em placas de fibrocimento. O cimento foi substituído em volume nas percentagens de 0, 15, 25 e 50%. Essas combinações foram reforçadas com fibras de celulose e polipropileno (PP). A investigação foi realizada analisando ensaios de fluorescência de raios X, difração de raios – X, microscopia eletrônica de varredura e análise termogravimétrica. Além disso, ensaios de resistência mecânica à flexão das placas foram realizadas em amostras produzidas com base em um processo de sucção e prensagem. Todos os ensaios foram realizados com amostras aos 28 dias de hidratação. Os resultados da caracterização microestutural apresentaram uma redução do hidróxido de cálcio conforme aumenta o teor de RCV devido ao consumo deste composto em consequência da reação pozolânica, também foram observados picos de C-S-H em todas as misturas. Considerando- se os resultados das propriedades mecânicas à flexão, todos os percentuais de substituição apresentaram resultados satisfatórios de acordo com a norma NBR 15498 em relação à resistência à flexão para uso em fachadas externas.

Inconel 718 alloy is the most used nickel-based superalloy owing to its characteristics of excellent mechanical and chemical properties at high temperatures and relatively low cost in comparison with other alloys. Nevertheless, the mechanical properties and components with intricate geometric shapes usually lead to difficulty in machining this alloy. This article reports a literature review on the machining performance of Inconel 718 alloy using conventional machining processes as well as electrical discharge machining. Based on the literature review, it is possible to highlight that for conventional machining, non-uniform flank wear and notch at the depth of cut are the leading causes for cutting tool failure when machining Inconel 718. Abrasion is the prominent wear mechanism, followed by diffusion, adhesion, and chipping. Regarding the assessed literature, 65% used cemented carbide as cutting tool material, 20% used ceramic cutting tools, and 15% applied CBN tools. For ED-machining, copper is the most used material as a tool electrode, followed by brass and graphite. Regarding the electrical variables, discharge currents applied are from 10 to 20 A, and the pulse duration varies from 50 to 200 µs. The thickness of the white layer, varying from 3 to 50 μm, depends directly on the combination of process parameters, which involves the variation of discharge current and pulse duration.

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Steels can go through a duplex treatment process, consisting of depositing a physical vapor deposition (PVD) coating on plasma-nitrided substrates. The coating layer varies from 1.5 to 5 µm, depending on the application needs. The work's objective is to analyze the performance and evaluate the mechanical characteristics of titanium nitride (TiN) and titanium aluminum nitride (TiAlN) coatings deposited in AISI 4140 with quenched/tempered or plasma-nitrided treatment. Scanning electron microscopy/energy dispersive spectroscopy and X-ray diffraction performed the microstructural and chemical characterization of the duplex-treated samples. The mechanical properties were measured by performing nanohardness tests, allowing the extraction of hardness and elastic modulus out of the load/unload behavior of the samples, and the scratch test according to ASTM C1624-05 (2010), Standard Test Method for Adhesion Strength and Mechanical Failure Modes of Ceramic Coatings by Quantitative Singles Point Scratch Testing (Superseded), coupled with acoustic emission analysis, probed adhesion of the TiN and TiAlN coating on the steel substrates. Also, pin-on-disk tribological tests probed the wear resistance of the duplex-treated samples. It was found that the nitriding process increases the surface hardness and elastic modulus. The TiAlN coating has the highest load capacity with the least amount of wear. The adhesion of the TiAlN coatings is worse than TiN.