Browsing by Author "Fonseca, João Gomes Portugal da"
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- Refractory ceramics in the context of the fabrication of rocket nozzles: Conventional alumina and industrial waste alumina-silicate refractory compositionsPublication . Fonseca, João Gomes Portugal da; Silva, Abílio Manuel Pereira da; Brojo, Francisco Miguel Ribeiro ProençaSpace exploration has had a regrowth in interest as the possibility for landing man on the moon returns following the appearance of commercial flights to high orbit among other recent developments. At the centre of the space capabilities of the human race are the vehicles it uses to achieve orbit and destinations beyond, these powerful vehicles are composed of many parts, and each must be studied and developed with various factors in mind. In this study the nozzle of the rocket engines, that quite literally power the human capability to explore space, are the focal point, specifically the materials used in these components. Traditionally composed of metallic alloys, the rocket nozzles are subject to extreme thermal environments, that lead to challenges such as the oxidation of the materials. Furthermore, the space exploration industry in inherently wasteful and costly, as well as rather environmentally unfavourable. In this study, therefore, a different approach is presented, in which refractory ceramics are studied as an alternative material for rocket nozzles, but also refractory ceramics composed of reutilized by-products of mines and thermoelectric centrals, materials that would by otherwise considered waste and disregarded. A closer look to these unrefined materials shows promise in its capabilities, as these are mainly composed by materials usually utilized in traditional refractory ceramics, and moreover in ceramics presented in study cases for rocket nozzle applications, like SiO2 and Al2O3. The manufacturing process and challenges of such an approach are studied and discussed and the final refractory ceramic of fly-ash and mines sands are compared with and almost pure Al2O3 ceramic benchmark. The results indicate that by utilizing unrefined products losses in properties will be expected. However, capable ceramics are still consistently achievable using these alternative materials.