Full text
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| Author(s): |
Katia Marques
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Escola Politécnica (EP/BC) |
| Defense date: | 1994-08-19 |
| Examining board members: |
Helio Goldenstein;
Francisco Ambrozio Filho;
Rezende Gomes dos Santos
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| Advisor: | Helio Goldenstein |
| Abstract | |
The resistance to creep of zinc-aluminium alloys at temperatures above 100°C can be improved by fiber or particle reinforcements (for instance, steel fibers). When molten zinc aluminium alloys are brought into contact with steel fibers, intermetallic compounds form at the interface. This fact enables the production of a composite material without application of further pressure to the system. Nevertheless, the existence of reaction products at the interface can deteriorate the mechanical properties of such materials. The morphological and chemical characterization of the reaction products, as well as the study of their growth kinetics is of utter importance for the assessment of these composite materials performance, and thus, is the main objective pursued here. Experiments similar to the hot dip galvanizing process were carried out. Low carbon steel wires ABNT 1010 with diameters of 4mm were dipped for 10, up to 810 seconds, in zinc baths containing 5 and l5wt%Al, at 450, 510, 570 e 640°C. Before dipping, the wires were ground, degreased, pickled and fluxed. The techniques used to study the reaction products were: optical microscopy, X-ray diffraction and energy dispersive spectroscopy. The rate at which the wires were consumed was evaluated by the differences between their initial and final diameters. Results of microstructure and chemical analysis were employed to identify the phases formed in the reaction zone. The reaction sequence proposed is supported by composition paths originated across the reaction zone. The diameter variations of wires dipped in zinc melts containing l5wt%Al indicated that the steel wires were consumed according to an exponential law with time, where the exponent n varies from 0 . 31 to 0.41. (AU) | |