Browsing by Author "Viana, F."
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- Investigations on the oxidation of Zn-coated steel cablesPublication . Pinto, Gustavo Filipe; Silva, Francisco J. G.; Baptista, Andresa; Campilho, Raul; Viana, F.The automotive component industry has been constantly being studying to improve its performance. Bowden cables are present in opening doors, moving windows and others. In braided cables formed by galvanized wires with Zn steel exposed to the usual environmental conditions, the generation of ZnO appears, a phenomenon known as "white corrosion". The investigation consisted of mitigating the causes of the ZnO formation. Scanning electron microscopy (SEM) and Electron Probe Micro-Analyzer (EPMA) technology, allowed to detect that the generation of ZnO was induced by the presence of nucleating elements of ZnO on the surface of the steel cable before galvanizing with Zn. The S, Cl and O became visible in the interface between coating and substrate. This allowed concluding, under the coating, there were harmful products capable of triggering the ZnO nucleation reaction. So, the storage and cleaning of the steel wire before galvanizing is essential to prevent the ZnO formation.
- Studying the ZnO formation in coated steel wire ropes for the automotive industryPublication . Pinto, Gustavo Filipe; Silva, Francisco J. G.; Baptista, Andresa; Fecheira, J.S.; Campilho, R.D.S.G.; Viana, F.Bowden cables are abundantly applied in the automotive assembly lines leading to drive various devices, such as opening trunk or the fuel tank cap, triggering the handbrake, opening the doors, etc. The cable used in automotive metallic harness is commonly constituted of braided wire galvanized steel, which has been studied to resist the weather aggressions typically imposed by the conditions under which usually work. However, to allow this operating in a steady state way, the braided wire must have the appropriate quality. This work study the reasons of the formation of relatively abundant quantities of zinc oxide (ZnO) in metallic cables used in the automotive industry, a few weeks after their manufacture. It was concluded that there were serious shortcomings of cable cleaning between the wire forming operations and galvanizing, with deposition of ZnO enhancing elements in the interface, which would prove to be crucial to nucleation and development of ZnO on the surface. Thus, the main contribution of this work is to identify and describe the elements able to generate ZnO in coated steel wires, avoiding this phenomenon in the industry.