Cu-Nb microcomposites are attractive in magnet pulsed field technology applications due to their anomalous mechanism of mechanical strength and high electrical conductivity. In this sense, recently it was conceived the use of Cu 15% vol. Nb wires to operate as a high tensile strength cable for a diamond cutting tool (diamond wires) for marble and granite slabbing. The multifilamentary Cu 15% vol. Nb composite was obtained using a new processing route, starting with niobium bars bundled into copper tubes, without arc melting. Cold working techniques, such as swaging and wire drawing, combined with heat treatments such as sintering and annealing, and tube restacking were employed. The tensile property of the composite was measured as a function of the niobium filaments dimensions and morphology into the copper matrix, in the several processing steps. An ultimate tensile strength (UTS) of 960 MPa was obtained for an areal reduction (R = Ao/A, with Ao-initial cross section area, and A-final cross section area) of 4x10(8) X, in which the niobium filaments reached thickness less than 20 nm. The anomalous mechanical strength increase is attributed to the fact that the niobium filaments acts as a barrier to copper dislocations
We propose an original route to process diamond wires, denominated In Situ Technology, whose fabrication involves mechanical conformation processes, such as rotary forging, copper tubes restacking, and thermal treatments, such as sintering and recrystallisation of a bronze 4 wt.% diamond composite. Tensile tests were performed, reaching an ultimate tensile strength (UTS) of 230 MPa for the diameter of Æ = 1.84 mm. Scanning electron microscopy showed the diamond crystals distribution along the composite rope during its manufacture, as well as the diamond adhesion to the bronze matrix. Cutting tests were carried out with the processed wire, showing a probable performance 4 times higher than the diamond sawing discs, however its probable performance was about 5 to 8 times less than the conventional diamond wires (pearl system) due to the low abrasion resistance of the bronze matrix, and low adhesion between the pair bronze-diamond due to the use of not metallised diamond single crystals
INTRODUÇÃOA zircônia (ZrO 2 ) tem mostrado grande destaque entre as cerâmicas avançadas, atraindo muito interesse de pesquisadores em seus vários campos de atuação. As aplicações mais promissoras são como cerâmicas estruturais (partes de motores de combustão, palhetas de turbinas, ferramentas de corte, partes de implantes ortopédicos) e como eletrólitos sólidos (sensores de oxigênio, células de combustível, bombas de oxigênio) [1].A zircônia pura apresenta três fases cristalinas, à pressão ambiente, que são: monoclínica -m (até 1170 o C), tetragonal -t (de 1170 até 2370 o C), e cúbica -c (de 2370 a 2680 o C) [2]. Devido à elevada variação volumétrica associada à transição t-m, a zircônia pura não apresenta aplicabilidade prática como material de engenharia. A adição de certos óxidos estabilizantes é imprescindível para manter as fases polimórficas de temperaturas elevadas, em temperatura ambiente. Dentre estes aditivos, a ítria (Y 2 O 3 ) se destaca como o estabilizante mais utilizado para a estabilização de fase tetragonal do ZrO 2 , o qual é conhecido como fase tenaz e dura, à temperatura ambiente, o que possibilita o uso deste material como cerâmica avançada [3], e notadamente em aplicações como ferramenta de corte.A estabilidade dos polimorfos do ZrO 2 depende fortemente do tipo e quantidade de óxido que é usado para diminuir a temperatura da transformação t-m. Feder et al. [4]
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.